Three- and four-repeat tau regulate the dynamic instability of two distinct microtubule subpopulations in qualitatively different manners. Implications for neurodegeneration.

The microtubule-associated protein tau is implicated in the pathogenesis of many neurodegenerative diseases, including fronto-temporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), in which both RNA splicing and amino acid substitution mutations in tau cause dominantly inherited early onset dementia. RNA-splicing FTDP-17 mutations alter the wild-type approximately 50:50 3-repeat (3R) to 4-repeat (4R) tau isoform ratio, usually resulting in an excess of 4R tau. To examine further how splicing mutations might cause dysfunction by misregulation of microtubule dynamics, we used video microscopy to determine the in vitro behavior of individual microtubules stabilized by varying amounts of human 4R and 3R tau.

SNP detection using peptide nucleic acid probes and conjugated polymers: applications in neurodegenerative disease identification.

A strategy employing a combination of peptide nucleic acid (PNA) probes, an optically amplifying conjugated polymer (CP), and S1 nuclease enzyme is capable of detecting SNPs in a simple, rapid, and sensitive manner. The recognition is accomplished by sequence-specific hybridization between the uncharged, fluorescein-labeled PNA probe and the DNA sequence of interest. After subsequent treatment with S1 nuclease, the cationic water soluble CP electrostatically associates with the remaining anionic PNA/DNA complex, leading to sensitized emission of the labeled PNA probe via FRET from the CP.

Inability of tau to properly regulate neuronal microtubule dynamics: a loss-of-function mechanism by which tau might mediate neuronal cell death.

Interest in the microtubule-associated protein tau stems from its critical roles in neural development and maintenance, as well as its role in Alzheimer's, FTDP-17 and related neurodegenerative diseases. Under normal circumstances, tau performs its functions by binding to microtubules and powerfully regulating their stability and growing and shortening dynamics. On the other hand, genetic analyses have established a clear cause-and-effect relationship between tau dysfunction/mis-regulation and neuronal cell death and dementia in FTDP-17, but the molecular basis of tau's destructive action(s) remains poorly understood.

Clinical and biochemical manifestations and molecular characterization of the mutation HPRT Jerusalem.

A novel point mutation (I137T) was identified in the hypoxanthine-guanine phosphoribosyltransferase (HPRT) encoding gene, in a patient with partial deficiency of the enzyme. The mutation, ATT to ACT (substitution of isoleucine to threonine), occurred at codon 137, which is within the region encoding the binding site for 5-phosphoribosyl-1-pyrophosphate (PRPP). The mutation caused decreased affinity for PRPP, manifested clinically as a Lesch-Nyhan variant (excessive purine production and delayed acquisition of language skills).

Lung injury and mortality with hyperoxia are increased in peroxiredoxin 6 gene-targeted mice.

Overexpression of peroxiredoxin 6 (Prdx6) has been shown to protect lungs of mice against hyperoxia-mediated injury. In this study, we evaluated whether genetic inactivation of Prdx6 in mice increases sensitivity to oxygen toxicity. We evaluated mouse survival, lung histopathology, total protein and nucleated cells in bronchoalveolar lavage fluid (BALF), and oxidation of lung protein and lipids by measurement of protein carbonyls and thiobarbituric reactive substances (TBARS), respectively.

The powerful microbubble: from bench to bedside, from intravascular indicator to therapeutic delivery system, and beyond.

This review discusses the development, current applications, and therapeutic potential of ultrasound contrast agents. Microbubbles containing gases act as true, intravascular indicators, permitting a noninvasive, quantitative analysis of the spatial and temporal heterogeneity of blood flow and volumes within the microvasculature. These shelled microbubbles are near-perfect reflectors of acoustic ultrasound energy and, when injected intravenously into the bloodstream, reflect ultrasound waves within the capillaries without disrupting the local environment.

Effect of contrast enhancement on measurement of carotid artery intimal medial thickness.

Previous studies have used standard B-mode ultrasound to quantify the aggregate mean intimal medial thickness (IMT) of the near and far wall of the common carotid artery (CCA). Many investigators have had difficulty in accurately evaluating the near wall IMT secondary to difficulty in discerning the vessel lumen and intima. The purpose of this study is to determine the effect of contrast enhanced ultrasound on IMT measurement when compared with non-enhanced images.

Role of surrogate markers in assessing patients with diabetes mellitus and the metabolic syndrome and in evaluating lipid-lowering therapy.

Diabetes mellitus and the metabolic syndrome (MS) are reaching epidemic proportions in the United States, and cardiovascular disease continues to be the leading cause of death among patients with diabetes. A range of noninvasive screening tools may help reduce the morbidity and mortality of patients with diabetes because of early detection of subclinical cardiovascular disease and active monitoring of the effectiveness of therapy. Surrogate markers of subclinical disease include conventional and contrast-enhanced ultrasound imaging of carotid artery intima-media thickness (c-IMT), 2-dimensional echocardiography, coronary artery calcium imaging, cardiac magnetic resonance imaging, ankle-brachial indices, and brachial artery reactivity testing.

Adenovirus-mediated transfer of the 1-cys peroxiredoxin gene to mouse lung protects against hyperoxic injury.

1-Cys peroxiredoxin (1-cysPrx) is a novel antioxidant enzyme that has been shown to reduce a broad spectrum of peroxides including phospholipid hydroperoxides. We tested the hypothesis that adenovirus-mediated transfer of the 1-cysPrx gene can protect lungs of mice from oxidant injury. Mice infected with AdLacZ/AdNull were used as a control (AdCon).

Evidence for two distinct binding sites for tau on microtubules.

The microtubule-associated protein tau regulates diverse and essential microtubule functions, from the nucleation and promotion of microtubule polymerization to the regulation of microtubule polarity and dynamics, as well as the spacing and bundling of axonal microtubules. Thermodynamic studies show that tau interacts with microtubules in the low- to mid-nanomolar range, implying moderate binding affinity. At the same time, it is well established that microtubule-bound tau does not undergo exchange with the bulk medium readily, suggesting that the tau-microtubule interaction is essentially irreversible.

Modulation of microtubule dynamics by tau in living cells: implications for development and neurodegeneration.

The neural microtubule-associated protein tau binds to and stabilizes microtubules. Because of alternative mRNA splicing, tau is expressed with either 3 or 4 C-terminal repeats. Two observations indicate that differences between these tau isoforms are functionally important.

Activation of the antioxidant enzyme 1-CYS peroxiredoxin requires glutathionylation mediated by heterodimerization with pi GST.

1-cys peroxiredoxin (1-cysPrx), a member of the peroxiredoxin superfamily, can protect cells against membrane oxidation through glutathione (GSH)-dependent reduction of phospholipid hydroperoxides to corresponding alcohols. However, purified native or recombinant enzyme in vitro generally lacks GSH peroxidase (GPx) activity because of oxidation of its single conserved cysteine. Reduction of the resultant oxidized cysteine is difficult because of its protected location within the homodimer formed by the oxidized protein monomers.

Comparison of echocardiography using tissue harmonics and contrast harmonics with radionuclide angiography for the assessment of left ventricular function.

Background: Left ventricular ejection fraction (LVEF) is a significant predictor of morbidity and mortality; however, the optimal noninvasive modality for the quantitative determination of LVEF is not apparent.

Hypothesis: We verified the hypothesis that the various echocardiographic methods of assessing LVEF using the Method of Discs with contrast (Optison human albumin microspheres; Amersham Health, Princeton, NJ) and visual assessment of LVEF using tissue harmonics and contrast harmonics compare favorably with radionuclide angiography (RNA).

Methods: In a prospective analysis, 24 consecutive patients scheduled to undergo RNA had an echocardiogram using tissue harmonics and contrast harmonics on the same day.

Emerging, noninvasive surrogate markers of atherosclerosis.

Noninvasive surrogate markers of atherosclerosis allow the physician to identify subclinical disease before the occurrence of adverse cardiovascular events, thereby limiting the need to perform invasive diagnostic procedures. Imaging modalities, such as carotid artery ultrasound, two-dimensional echocardiography, coronary artery calcium imaging, cardiac magnetic resonance imaging, ankle-brachial indices, brachial artery reactivity testing, and epicardial coronary flow reserve measurements, provide information that may improve the predictive value of a person's risk of developing clinically significant atherosclerotic disease. Newer imaging modalities have also emerged to bring insight into the pathophysiology and treatment of atherosclerosis.

1-Cys peroxiredoxin knock-out mice express mRNA but not protein for a highly related intronless gene.

1-Cys peroxiredoxin (1-cysPrx), a member of the peroxiredoxin family with a single conserved cysteine, is a unique antioxidant enzyme. We have generated mice in which the 1-cysPrx gene has been inactivated; they are viable and fertile. Mice have a highly related intronless gene (1-cysPrx-P1, GenBank accession number AF085220) with the same length of open reading frame (224 aa) as 1-cysPrx but located on a different chromosome.

Cadaver-donor renal transplantation of children in Israel (1990-2001): racial disparities in health care delivery?

Objective: To evaluate the allocation and outcome of cadaver-donor renal transplantation (CDRTx) among Jewish and Arab children in Israel.

Methods: Data on CDRTxs in patients who had end-stage renal failure (ESRF), were younger than 18 years, and were on dialysis treatment were obtained for the 11-year period of January 1990 to December 2000 from the Israeli Dialysis and Transplant Registry, supplemented by 10 years of follow-up (January 1991-December 2000) from our own center.

Results: The Israeli Dialysis and Transplant Registry data show that 64 of 130 available cadaver-donor kidneys (CDKs) were allocated to Jewish patients (49.

Differential regulation of microtubule dynamics by three- and four-repeat tau: implications for the onset of neurodegenerative disease.

The microtubule (MT)-associated protein tau is important in neuronal development and in Alzheimer's and other neurodegenerative diseases. Genetic analyses have established a cause-and-effect relationship between tau dysfunction/misregulation and neuronal cell death and dementia in frontotemporal dementia and parkinsonism associated with chromosome 17; several mutations causing this dementia lead to increased ratios of four-repeat (4R) to three-repeat (3R) wild-type tau, and an attractive hypothesis is that the abnormally high ratio of 4R to 3R tau might lead to neuronal cell death by altering normal tau functions in adult neurons. Thus, we tested whether 3R and 4R tau might differentially modulate the dynamic instability of MTs in vitro using video microscopy.

Induction of 1-cys peroxiredoxin expression by oxidative stress in lung epithelial cells.

1-Cys peroxiredoxin (1-cysPrx), a member of the peroxiredoxin family that contains a single conserved cysteine residue, reduces a broad spectrum of hydroperoxides. We studied changes in 1-cysPrx expression in rat lungs and lung cell lines in response to oxidative stress due to hyperoxia, H2O2, or paraquat. After 60 h of hyperoxia (>95% O2), mRNA and protein levels of 1-cysPrx and peroxidase activity were significantly elevated in rat lungs by approximately 1.

Microtubule-dependent oligomerization of tau. Implications for physiological tau function and tauopathies.

The accumulation of abnormal tau filaments is a pathological hallmark of many neurodegenerative diseases. In 1998, genetic analyses revealed a direct linkage between structural and regulatory mutations in the tau gene and the neurodegenerative disease, frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17). Importantly, the FTDP-17 phenotype is transmitted in a dominant rather than a recessive manner.

Item-by-item factor analysis of the Yale-Brown Obsessive Compulsive Scale Symptom Checklist.

Clinical subtypes of obsessive-compulsive disorder may have differing pathophysiological mechanisms and treatment outcomes. The subtypes identified by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) Symptom Checklist, clustered by clinical consensus, have never been subject to statistical validation. A factor analysis using a sample of 160 patients with OCD was conducted to determine whether factor analytically derived categories are identical to extant clinically determined categories.

Mutated podocin manifesting as CMV-associated congenital nephrotic syndrome.

We report a girl with congenital nephrotic syndrome (CNS) associated with cytomegalovirus (CMV) infection and histological findings on renal biopsy that suggested a causal relationship between the two. She was subsequently found to be homozygous for a nonsense mutation in the NPHS2 gene encoding podocin (R138X), which is the true cause of her NS. Based on review of the literature and our findings in this patient, we propose that the clinical entity known as CMV causing CNS may not exist.

A novel point mutation (I137T) in the conserved 5-phosphoribosyl-1-pyrophosphate binding motif of hypoxanthine-guanine phosphoribosyltransferase (HPRTJerusalem) in a variant of Lesch-Nyhan syndrome.

We identified a novel point mutation (I137T) in the hypoxanthine-guanine phosphoribosyltransferase (HPRT; EC 2.4.2.

An antisense oligonucleotide to 1-cys peroxiredoxin causes lipid peroxidation and apoptosis in lung epithelial cells.

1-cys peroxiredoxin (1-cysPrx), a member of the peroxiredoxin superfamily, reduces phospholipid hydroperoxides as well as organic peroxides and H(2)O(2). To determine the physiological function(s) of 1-cysPrx, we have used an antisense strategy to suppress endogenous 1-cysPrx in L2 cells, a rat lung epithelial cell line. A 25-base antisense morpholino oligonucleotide was designed to bind a complementary sequence overlapping the translational start site (-18 to +7) in the rat 1-cysPrx mRNA, blocking protein synthesis.

1-Cys peroxiredoxin overexpression protects cells against phospholipid peroxidation-mediated membrane damage.

1-Cys peroxiredoxin (1-cysPrx) is a novel antioxidant enzyme able to reduce phospholipid hydroperoxides in vitro by using glutathione as a reductant. This enzyme is widely expressed and is enriched in lungs. A fusion protein of green fluorescent protein with 1-cysPrx was stably expressed in a lung-derived cell line (NCI-H441) lacking endogenous enzyme.

Hyperhomocysteinemia in children on renal replacement therapy.

Hyperhomocysteinemia is an independent risk factor for the development of atherosclerosis in adult patients on dialysis or after kidney transplantation. There are few data on homocysteine (Hcy) concentrations in children under these circumstances. The aim of our study was to evaluate plasma Hcy levels and their determining factors in children on renal replacement therapy.