Liquid-state theory of charged colloids

A simple theory of the fluid state of a charged colloidal suspension is proposed. The full free energy of a polyelectrolyte solution is calculated. It is found that the counterions condense onto the polyions forming clusters composed of one polyion and n counterions. The distribution of cluster sizes is determined explicitly. In agreement with the current experimental and Monte Carlo results, no liquid-gas phase separation was encountered.Comment: 4 pages, 2 Postscript figures, uses multicol.sty; changed conten

Donnan equilibrium and the osmotic pressure of charged colloidal lattices

We consider a system composed of a monodisperse charge-stabilized colloidal suspension in the presence of monovalent salt, separated from the pure electrolyte by a semipermeable membrane, which allows the crossing of solvent, counterions, and salt particles, but prevents the passage of polyions. The colloidal suspension, that is in a crystalline phase, is considered using a spherical Wigner-Seitz cell. After the Donnan equilibrium is achieved, there will be a difference in pressure between the two sides of the membrane. Using the functional density theory, we obtained the expression for the osmotic pressure as a function of the concentration of added salt, the colloidal volume fraction, and the size and charge of the colloidal particles. The results are compared with the experimental measurements for ordered polystyrene lattices of two different particle sizes over a range of ionic strengths and colloidal volume fractions.Comment: 8 pages, 4 Postscript figures, uses multicol.sty, to be published in European Physical Journal

Liquid Polymorphism and Density Anomaly in a Lattice Gas Model

We present a simple model for an associating liquid in which polymorphism and density anomaly are connected. Our model combines a two dimensional lattice gas with particles interacting through a soft core potential and orientational degrees of freedom represented through thermal \char`\"{}ice variables\char`\"{} . The competition between the directional attractive forces and the soft core potential leads to a phase diagram in which two liquid phases and a density anomaly are present. The coexistence line between the low density liquid and the high density liquid has a positive slope contradicting the surmise that the presence of a density anomaly implies that the high density liquid is more entropic than the low density liquid

The use of the role repertory grid technique in generating clinical hypotheses

Dept. of Psychology. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1983 .G723. Source: Masters Abstracts International, Volume: 40-07, page: . Thesis (M.A.)--University of Windsor (Canada), 1983

Passive immunotherapy against Aβ in aged APP-transgenic mice reverses cognitive deficits and depletes parenchymal amyloid deposits in spite of increased vascular amyloid and microhemorrhage

BACKGROUND: Anti-Aβ immunotherapy in transgenic mice reduces both diffuse and compact amyloid deposits, improves memory function and clears early-stage phospho-tau aggregates. As most Alzheimer disease cases occur well past midlife, the current study examined adoptive transfer of anti-Aβ antibodies to 19- and 23-month old APP-transgenic mice. METHODS: We investigated the effects of weekly anti-Aβ antibody treatment on radial-arm water-maze performance, parenchymal and vascular amyloid loads, and the presence of microhemorrhage in the brain. 19-month-old mice were treated for 1, 2 or 3 months while 23-month-old mice were treated for 5 months. Only the 23-month-old mice were subject to radial-arm water-maze testing. RESULTS: After 3 months of weekly injections, this passive immunization protocol completely reversed learning and memory deficits in these mice, a benefit that was undiminished after 5 months of treatment. Dramatic reductions of diffuse Aβ immunostaining and parenchymal Congophilic amyloid deposits were observed after five months, indicating that even well-established amyloid deposits are susceptible to immunotherapy. However, cerebral amyloid angiopathy increased substantially with immunotherapy, and some deposits were associated with microhemorrhage. Reanalysis of results collected from an earlier time-course study demonstrated that these increases in vascular deposits were dependent on the duration of immunotherapy. CONCLUSIONS: The cognitive benefits of passive immunotherapy persist in spite of the presence of vascular amyloid and small hemorrhages. These data suggest that clinical trials evaluating such treatments will require precautions to minimize potential adverse events associated with microhemorrhage

Dysregulation of Na+/K+ ATPase by amyloid in APP+PS1 transgenic mice

BACKGROUND: The pathology of Alzheimer's disease (AD) is comprised of extracellular amyloid plaques, intracellular tau tangles, dystrophic neurites and neurodegeneration. The mechanisms by which these various pathological features arise are under intense investigation. Here, expanding upon pilot gene expression studies, we have further analyzed the relationship between Na+/K+ ATPase and amyloid using APP+PS1 transgenic mice, a model that develops amyloid plaques and memory deficits in the absence of tangle formation and neuronal or synaptic loss. RESULTS: We report that in addition to decreased mRNA expression, there was decreased overall Na+/K+ ATPase enzyme activity in the amyloid-containing hippocampi of the APP+PS1 mice (although not in the amyloid-free cerebellum). In addition, dual immunolabeling revealed an absence of Na+/K+ ATPase staining in a zone surrounding congophilic plaques that was occupied by dystrophic neurites. We also demonstrate that cerebral Na+/K+ ATPase activity can be directly inhibited by high concentrations of soluble Aβ. CONCLUSIONS: The data suggest that the reductions in Na+/K+ ATPase activity in Alzheimer tissue may not be purely secondary to neuronal loss, but may results from direct effects of amyloid on this enzyme. This disruption of ion homeostasis and osmotic balance may interfere with normal electrotonic properties of dendrites, blocking intraneuronal signal processing, and contribute to neuritic dystrophia. These results suggest that therapies aimed at enhancing Na+/K+ ATPase activity in AD may improve symptoms and/or delay disease progression

Interview with John and Marcia Diamond by Mike Hastings

Biographical NoteJohn Nathan Diamond was born on November 12, 1954, in Bangor, Maine. His father, Nathan Diamond, was a musician and a teacher, and his mother, Eleanor Diamond, was active in the community and in local politics. John followed politics with his parents, who were registered Republicans until 1978 when they changed their party affiliation and became Democrats. As a teenager, John volunteered for Elmer Violette and Bill Hathaway in 1972. After graduating from Bangor High School, he attended the University of Maine, graduating in 1977. He became involved in the Carter and Muskie campaigns of 1976. He worked for the Lewiston Sun-Journal after college, covering local politics, and then took a job running Jim Henderson’s primary campaign of 1978. He worked for Bill Hathaway in the general election that year and then took a job as a staffer in the Maine state House majority office. In 1980, he was elected to a House seat representing Bangor, and in 1982 he was reelected unopposed. Not having to campaign much for himself, he worked for Mitchell’s 1982 campaign. He met Marcia in 1985 and they were married September 13, 1986. They have two children and live in Bangor, Maine, where John worked for the University of Maine system as executive director of external affairs at the time of this interview. Marcia LaRochelle Diamond was born on June 8, 1962, in Bath, Maine, to Mary Sullivan LaRochelle and Neil LaRochelle. Marcia was the fourth of six children. Her father was a principal in the Bath school system, and he ran a family business called LaRochelle and Sons Market Gardens. Her mother encouraged her to get involved in politics in order to broaden her experience beyond being a teacher, which was the career that Marcia aspired to achieve. Marcia attended the University of Maine, Farmington, graduating early in order to intern in Mitchell’s office in Washington D.C. She began in the press office, and when the term of her internship was over she was hired as assistant press secretary. After a few years, she moved back to Maine to provide Senator Mitchell’s office with a press presence at home. After marrying John and finding that Mitchell’s seat was safe for the 1988 campaign, Marcia retired from her political career and pursued teaching. She began teaching sixth grade at East Corinth School and became involved in the Odyssey of the Mind program. After a hiatus rearing her children, she returned to teaching at St. Mary’s Catholic School, which merged with St. John’s Catholic School in 2000 to become All Saints Catholic School, where Marcia served as principal at the time of this interview. SummaryInterview includes discussions of: growing up in Maine; the 1972 election; the University of Maine; the 1976 election; John’s running for the legislature in 1980; the Penobscot County Democrats; taking John’s seventy-five year old grandmother to see President Carter during his visit to Bangor in 1980; Bangor in the 1960s and 1970s; Marcia’s connection with Gayle Cory; Marcia’s internship in Mitchell’s Senate office in Washington, D.C. and subsequent work in Mitchell’s press office; Marcia’s decision to return to Maine; how John and Marcia met, their first date, and John’s proposal; how John got involved in Mitchell’s 1982 campaign; the field operation in 1982; how Mitchell developed his public persona; forecasting that nuclear and environmental issues would become crucial issues in the 1980s; the campaign strategy of following up on phone calls with letters about issues relevant to the phone conversation; the Fourth of July Parade in Bangor as a turning point in the 1982 campaign; election night, 1982; Marcia’s involvement with Odyssey of the Mind; John’s and Marcia’s small business; Marcia’s career in education; John’s work with Maine Public Broadcasting; how Marcia learned from Gayle Cory to never take “no” for an answer; and the forgotten luggage story

Development of outbred CD1 mouse colonies with distinct standardized gut microbiota profiles for use in complex microbiota targeted studies.

Studies indicate that the gut microbiota (GM) can significantly influence both local and systemic host physiologic processes. With rising concern for optimization of experimental reproducibility and translatability, it is essential to consider the GM in study design. However, GM profiles can vary between rodent producers making consistency between models challenging. To circumvent this, we developed outbred CD1 mouse colonies with stable, complex GM profiles that can be used as donors for a variety of GM transfer techniques including rederivation, co-housing, cross-foster, and fecal microbiota transfer (FMT). CD1 embryos were surgically transferred into CD1 or C57BL/6 surrogate dams that varied by GM composition and complexity to establish four separate mouse colonies harboring GM profiles representative of contemporary mouse producers. Using targeted 16S rRNA amplicon sequencing, subsequent female offspring were found to have similar GM profiles to surrogate dams. Furthermore, breeding colonies of CD1 mice with distinct GM profiles were maintained for nine generations, demonstrating GM stability within these colonies. To confirm GM stability, we shipped cohorts of these four colonies to collaborating institutions and found no significant variation in GM composition. These mice are an invaluable experimental resource that can be used to investigate GM effects on mouse model phenotype