Effectiveness of Global, Low-Degree Polynomial Transformations for GCxGC Data Alignment.

As columns age and differ between systems, retention times for comprehensive two-dimensional gas chromatography (GCxGC) may vary between runs. To properly analyze GCxGC chromatograms, it often is desirable to align the retention times of chromatographic features, such as analyte peaks, between chromatograms. Previous work by the authors has shown that global, low-degree polynomial transformation functions, namely affine, second-degree polynomial, and third-degree polynomial, are effective for aligning pairs of two-dimensional chromatograms acquired with dual second columns and detectors (GC×2GC).

Programmed automation of modulator cold jet flow for comprehensive two-dimensional gas chromatographic analysis of vacuum gas oils.

A method is described for automating the regulation of cold jet flow of a comprehensive two-dimensional gas chromatograph (GCxGC) configured with flame ionization detection. This new capability enables the routine automated separation, identification, and quantitation of hydrocarbon types in petroleum fractions extending into the vacuum gas oil (VGO) range (IBP-540 degrees C). Chromatographic data acquisition software is programmed to precisely change the rate of flow from the cold jet of a nitrogen cooled loop modulator of a GCxGC instrument during sample analysis.

Neutron yields from 435 MeV/nucleon Nb stopping in Nb and 272 MeV/nucleon Nb stopping in Nb and Al.

Neutron fluences were measured from 435 MeV/nucleon Nb ions stopping in a Nb target and 272 MeV/nucleon Nb ions stopping in targets of Nb and Al for neutrons above 20 MeV and at laboratory angles between 3 degrees and 80 degrees. The resultant spectra were integrated over angles to produce neutron energy distributions and over energy to produce neutron angular distributions. The total neutron yields for each system were obtained by integrating over the angular distributions.

Production of neutrons from interactions of GCR-like particles.

In order to help assess the risk to astronauts due to the long-term exposure to the natural radiation environment in space, an understanding of how the primary radiation field is changed when passing through shielding and tissue materials must be obtained. One important aspect of the change in the primary radiation field after passing through shielding materials is the production of secondary particles from the breakup of the primary. Neutrons are an important component of the secondary particle field due to their relatively high biological weighting factors, and due to their relative abundance, especially behind thick shielding scenarios.

Antioxidants and cataract: (cataract induction in space environment and application to terrestrial aging cataract).

The effect of several antioxidants and cysteine-elevating precursor drugs (prodrugs) was tested on lens damage occurring after in vitro exposure to low levels of 60Co-gamma-irradiation, to simulate in vitro the exposure to radiation in vivo of (1) astronauts (2) jet crews (3) military radiation accident personnel. Tocopherol (100 microM), ascorbic acid (1 mM), R-alpha-lipoic acid (1 mM), and taurine (0.5 mM) protected against radiation-associated protein leakage.

Stimulus responses and amyloid precursor protein processing in DAMI megakaryocytes.

Platelets, when released as anuclear cells by their precursor megakaryocytes, already carry soluble proteolytic fragments of the amyloid precursor protein (APP) within their alpha-granules and intact APP in the alpha-granule membranes. In response to activation signals elicited by physiologic stimuli such as thrombin, platelets release their granules' soluble contents and translocate granule membrane-bound proteins to the plasma membrane. Because platelets carry >90% of the circulation's APP, activated platelets have been implicated as origins of the beta-amyloid peptide fragment of APP (A beta), whose deposition in the cerebrovasculature is characteristic of Alzheimer's disease.

Unique CD8+ T cell-rich lymphoid aggregates in human uterine endometrium.

Using confocal scanning laser microscopy of viable tissue sections, we have demonstrated organized lymphoid aggregates (LA), that have a unique structure, in the stratum basalis of uterine endometrium. These LA consist of a core of B cells surrounded by more numerous T cells and an outer halo of monocytes/ macrophages. The T cells in the LA were almost exclusively CD8+CD4-.

Moderate and advanced Alzheimer's patients exhibit platelet activation differences.

We previously reported that platelets from advanced sporadic Alzheimer's disease (AD) patients exhibit two defects: first, an aberrant signal transduction presenting as a thrombin-induced hyperacidification, which is more severe for donors with the apolipoprotein E4 allele (apoE4), and second, an AD-specific Amyloid Precursor Protein (APP) processing defect that presents as retention of APP on the activated platelets' surface and in independent of the apo E allele. This retention of membrane APP correlates with decreased release of soluble APP. To determine at what stage in the disease progression these defects appear, we performed signal transduction and secretion studies on moderate AD patients.

Activated Alzheimer disease platelets retain more beta amyloid precursor protein.

Upon activation, platelet alpha-granules' soluble contents are secreted and membrane-bound contents are translocated to the plasma membrane. Membrane-bound proteins include the beta-amyloid precursor protein (APP) from which the beta-amyloid (A beta) deposits found surrounding the cerebrovasculature of patients with Alzheimer's Disease (AD) may originate. We show here that activated platelets from AD patients exhibit less APP processing, retain more of the protein on their surface, and secrete less as soluble fragments than do controls.

Maintenance of hepatic glutathione homeostasis and prevention of acetaminophen-induced cataract in mice by L-cysteine prodrugs.

Administration of acetaminophen (ACP, 3.0 mmol/kg, i.p.

An HPLC radiotracer method for assessing the ability of L-cysteine prodrugs to maintain glutathione levels in the cultured rat lens.

Purpose: To apply a high performance liquid chromatographic radiotracer method to test a variety of L-cysteine prodrugs and one dipeptide prodrug for their ability to synthesize glutathione in cultured rat lenses.

Methods: Rat lenses were incubated for 48 h in a medium containing [14C(U)]-glycine and prodrugs. Following homogenization and derivatization, lens extracts were analyzed to determine the extent of biosynthetic incorporation of this labeled amino acid into [14C]-glutathione using high performance liquid chromatography with radioisotope and ultraviolet absorption detection.

An HPLC radiotracer method for assessing the ability of L-Cysteine prodrugs to maintain glutathione levels in the cultured rat lens.

Purpose. To apply a high performance liquid chromatographic radiotracer method to test a variety of L-cysteine prodrugs and one dipeptide prodrug for their ability to synthesize glutathione in cultured rat lenses. Method.

Augmentation of human and rat lenticular glutathione in vitro by prodrugs of gamma-L-glutamyl-L-cysteine.

A marked age-related decrease in glutathione (GSH) levels as well as depression of gamma-glutamylcysteine synthetase activity are factors that are believed to render the aged lens more susceptible to oxidative stress and, therefore, to cataractogenesis. Providing gamma-L-glutamyl-L-cysteine, the dipeptide precursor of GSH, would effectively bypass the compromised first step in its biosynthesis and should protect the lens from GSH depletion. Accordingly, some bioreversible sulfhydryl-, amino-, and C-terminal carboxyl-protected prodrug forms of this dipeptide were prepared.

Prevention of naphthalene-induced cataract and hepatic glutathione loss by the L-cysteine prodrugs, MTCA and PTCA.

Rapid-onset cataracts were induced in SPF C57 bl/6 mice by intraperitoneal administration of naphthalene following cytochrome P-450 isozyme induction with phenobarbital. Several L-cysteine prodrugs with masked sulfhydryl groups in the form of thiazolidine-4-carboxylic acids, as well as N-acetyl-L-cysteine, N,S-bis-acetyl-L-cysteine and glutathione ethyl ester, were evaluated for their ability to maintain hepatic and lenticular glutathione at near-normal levels and to prevent naphthalene-induced cataract formation. Each prodrug was administered at three specified times to a cumulative total of 1.

Prevention of acetaminophen- and naphthalene-induced cataract and glutathione loss by CySSME.

Purposes: To assess the efficacy of 2-mercaptoethanol/L-cysteine mixed disulfide (CySSME) as an L-cysteine prodrug suitable for glutathione biosynthesis in rat lenses in vitro, as an agent for the prevention of acetaminophen- and naphthalene-induced murine cataract in genetically-susceptible mice, and as an agent for maintenance of near-normal glutathione levels in lenses and livers of mice subjected to acetaminophen and naphthalene at cataractogenic doses.

Methods: Synthetic CySSME was added as a prodrug to rat lens culture medium devoid of L-cystine and L-methionine but containing [14C(U)]-glycine. After a 48-hour period of incubation, extracts of rat lenses were prepared for separation of [14C]-glutathione by high-performance liquid chromatography (HPLC) with a radioisotope detector to determine the extent of its biosynthesis.

Protection against acetaminophen-induced hepatotoxicity by L-CySSME and its N-acetyl and ethyl ester derivatives.

We have recently observed that S-(2-hydroxyethylmercapto)-L-cysteine (L-CySSME), the mixed disulfide of L-cysteine and 2-mercaptoethanol, prevented cataracts induced in mice by acetaminophen (ACP) by functioning as a prodrug of L-cysteine and protecting the liver. This prompted the evaluation of the more lipophilic N-acetyl (Ac-CySSME) and ethyl ester (Et-CySSME) derivatives of L-CySSME as proprodrug forms, as well as the "D" enantiomer, as hepatoprotective agents. Serum ALT levels were measured at 24 hours after a toxic but nonlethal dose of ACP that insured 48 hour survival of the animals.

Influence on lenticular glutathione research.

Otto Hockwin influenced the early research career in ophthalmic biochemistry of William Rathbun in several ways. These included multiple exposures via symposia to the European research community, providing editorial experience and encouragement to expand fundamental glutathione enzyme research to the problems of aging, species variation and anti-cataract drug development.

The effects of age on glutathione peroxidase and glutathione reductase activities in lenses of Old World simians and prosimians.

The effects of age on the activities of the two enzymes of the glutathione redox cycle, glutathione peroxidase and glutathione reductase, were studied in lenses of primates. Three species were Old World simians (orangutan, olive baboon and pigtail monkey) and two were prosimians (galago and mouse lemur). Glutathione peroxidase activity of the olive baboon lens increased steadily with age while that of the pigtail monkey increased during the first 6-8 years and then plateaued.

Glutathione metabolism in primate lenses: A phylogenetic study of glutathione synthesis and glutathione redox cycle enzyme activities.

Lens wet weights, soluble protein, and activities of γ-glutiamylcysteine synthetase, glutathione synthetase, glutathione peroxidase, and glutathione reductase were determined in primate lenses. The primary sources of lenses were middle-aged adult animals. The Primates, from 23 genera, were categorized into six superfamilies: hominoids (five species), Old World monkeys (seven species), New World monkeys (five species), tarsiers (two species), lemurs (six species), and lorisids (three species).

Non-age related differences in thrombin responses by platelets from male patients with advanced Alzheimer's disease.

Alzheimer's Disease(AD), characterized by a deposition of beta-amyloid peptide (beta/A4) in the brain and in the cerebral microvasculature of affected individuals, is derived from its precursor protein (beta APP) via proteolytic processing by enzyme(s) which have not yet been characterized or localized. Since platelets carry APP in one of their granules, they have been implicated as a source of the beta/A4 deposits in the microvasculature of AD patients, attributable to either an abnormality in the platelets' stimulus response, in the quantity or nature of the APP they release upon activation and/or in the processing of that protein. We show here that platelets from patients with severe AD have abnormal stimulus responses to alpha-thrombin.

Activity loss of glutathione synthesis enzymes associated with human subcapsular cataract.

Purpose: To assess the activities of the two enzymes required for glutathione synthesis, gamma-glutamylcysteine synthetase and glutathione synthetase, in various forms of human cataracts.

Methods: The Cooperative Cataract Research Group cataract classification method and standard enzyme assay procedures were used.

Results: An inverse relationship was shown between residual activity of each of the glutathione synthesis enzymes and degree of subcapsular cataract.

The effects of age on glutathione synthesis enzymes in lenses of Old World simians and prosimians.

The activities of gamma-glutamylcysteine synthetase and glutathione synthetase, the two enzymes required for glutathione synthesis, were determined as a function of age in lenses of three species of Old World higher primates: orangutan, pigtail monkey and olive baboon. These were compared to enzyme activities in lenses of two prosimians: mouse lemur and galago. gamma-Glutamylcysteine synthetase activity decreased as a function of age in all three Old World simians.