987 resultados para Davis, Matthew L. (Matthew Livingston), 1773-1850
Resumo:
Neuropathological and brain imaging studies suggest that schizophrenia may result from neurodevelopmental defects. Cytoarchitectural studies indicate cellular abnormalities suggestive of a disruption in neuronal connectivity in schizophrenia, particularly in the dorsolateral prefrontal cortex. Yet, the molecular mechanisms underlying these findings remain unclear. To identify molecular substrates associated with schizophrenia, DNA microarray analysis was used to assay gene expression levels in postmortem dorsolateral prefrontal cortex of schizophrenic and control patients. Genes determined to have altered expression levels in schizophrenics relative to controls are involved in a number of biological processes, including synaptic plasticity, neuronal development, neurotransmission, and signal transduction. Most notable was the differential expression of myelination-related genes suggesting a disruption in oligodendrocyte function in schizophrenia.
Resumo:
Transgenic mice expressing the sequences coding for the envelope proteins of the hepatitis B virus (HBV) in the liver have been used as a model of the HBV chronic carrier state. We evaluated the possibility of inducing a specific immune response to the viral envelope antigens and thus potentially controlling chronic HBV infection. Using HBV-specific DNA-mediated immunization in this transgenic model, we show that the immune response induced after a single intramuscular injection of DNA resulted in the complete clearance of circulating hepatitis B surface antigen and in the long-term control of transgene expression in hepatocytes. This response does not involve a detectable cytopathic effect in the liver. Adoptive transfer of fractionated primed spleen cells from DNA-immunized mice shows that T cells are responsible for the down-regulation of HBV mRNA in the liver of transgenic mice. To our knowledge, this is the first demonstration of a potential immunotherapeutic application of DNA-mediated immunization against an infectious disease and raises the possibility of designing more effective ways of treating HBV chronic carriers.
Resumo:
Vaccination of two chimpanzees against hepatitis B virus (HBV) by intramuscular injection of plasmid DNA encoding the major and middle HBV envelope proteins induced group-, subtype- and preS2-specific antibodies. These were initially of IgM isotype, and then they were of IgG (predominantly IgGl) isotype. The chimpanzee injected with 2 mg of DNA attained >100 milli-international units/ml of anti-HBs antibody after one injection and 14,000 milli-international units/ml after four injections. A smaller dose (400 microg) induced lower and transient titers, but a strong anamnestic response occurred 1 year later. Comparison with responses in 23 chimpanzees receiving various antigen-based HBV vaccines suggests that the DNA approach is promising for prophylactic immunization against HBV.
Resumo:
Endosperm development in Zea mays is characterized by a period of intense mitotic activity followed by a period in which mitosis is essentially eliminated and the cell cycle becomes one of alternating S and G phases, leading to endoreduplication of the nuclear DNA. The endosperm represents a significant contribution to the grain yield of maize; thus, methods that facilitate the study of cellular kinetics may be useful in discerning cellular and molecular components of grain yield. Two mathematical models have been developed to describe the kinetics of endosperm growth. The first describes the kinetics of mitosis during endosperm development; the second describes the kinetics of DNA endoreduplication during endosperm development. The mitotic model is a modification of standard growth curves. The endoreduplication model is composed of six differential equations that represent the progression of nuclei from one DNA content to another during the endoreduplication process. Total nuclei number per endosperm and the number of 3C, 6C, 12C, 24C, 48C, and 96C nuclei per endosperm (C is the haploid DNA content per nucleus) for inbred W64A from 8 to 18 days after pollination were determined by flow cytometry. The results indicate that the change in number of nuclei expressed as a function of the number of days after pollination is the same from one yearly crop to another. These data were used in the model to determine the endosperm growth rate, the maximum nuclei number per endosperm, and transition rates from one C value to the next higher C value. The kinetics of endosperm development are reasonably well represented by the models. Thus, the models provide a means to quantify the complex pattern of endosperm development.
Resumo:
Intramuscular injection of plasmid DNA expression vectors encoding the three envelope proteins of the hepatitis B virus (HBV) induced humoral responses in C57BL/6 mice specific to several antigenic determinants of the viral envelope. The first antibodies appeared within 1-2 weeks after injection of DNA and included antibodies of the IgM isotype. Over the next few weeks, an IgM to IgG class switch occurred, indicating helper T-lymphocyte activity. Peak IgG titers were reached by 4-8 weeks after a single DNA injection and were maintained for at least 6 months without further DNA injections. The antibodies to the envelope proteins reacted with group- and subtype-specific antigenic determinants of the HBV surface antigen (HBsAg). Expression vectors encoding the major (S) and middle (preS2 plus S) envelope proteins induced antibodies specific to the S protein and preS2 domain, and preS2 antibodies were prominent at early time points. In general, the expression vectors induced humoral responses in mice that mimic those observed in humans during the course of natural HBV infection.
Resumo:
The mechanism of cell cycle withdrawal during terminal differentiation is poorly understood. We report here that the cyclin-dependent kinase (CDK) inhibitor p21Cip1/WAF1 is induced at early times of both keratinocyte and myoblast differentiation. p21Cip1/WAF1 induction is accompanied by a drastic inhibition of total Cdk2, as well as p21Cip1/WAF1-associated CDK kinase activities. p21Cip1/WAF1 has been implicated in p53-mediated G1 arrest and apoptosis. In keratinocyte differentiation, Cip1/WAF1 induction is observed even in cells derived from p53-null mice. Similarly, keratinocyte differentiation is associated with induction of Cip1/WAF1 promoter activity in both wild-type and p53-negative keratinocytes. Induction of the Cip1/WAF1 promoter upon differentiation is abolished by expression of an adenovirus E1A oncoprotein (d1922/947), which is unable to bind p105-Rb, p107, or cyclin A but which still binds the nuclear phosphoprotein p300. Overexpression of p300 can suppress the E1A effect, independent of its direct binding to E1A. Thus, terminal differentiation-induced growth arrest in both keratinocyte and myoblast systems is associated with induction of Cip1/WAF1 expression. During keratinocyte differentiation, Cip1/WAF1 induction does not require p53 but depends on the transcriptional modulator p300.
Resumo:
Experimental allergic encephalomyelitis (EAE) is an autoimmune disease of the central nervous system that serves as a model for the human disease multiple sclerosis. We evaluated rolipram, a type IV phosphodiesterase inhibitor, for its efficacy in preventing EAE in the common marmoset Callithrix jacchus. In a blinded experimental design, clinical signs of EAE developed within 17 days of immunization with human white matter in two placebo-treated animals but in none of three monkeys that received rolipram (10 mg/kg s.c. every other day) beginning 1 week after immunization. In controls, signs of EAE were associated with development of cerebrospinal fluid pleocytosis and cerebral MRI abnormalities. In the treatment group, there was sustained protection from clinical EAE, transient cerebrospinal fluid pleocytosis in only one of three animals, no MRI abnormality, and marked reduction in histopathologic findings. Rolipram-treated and control animals equally developed circulating antibodies to myelin basic protein. Thus, inhibition of type IV phosphodiesterase, initiated after sensitization to central nervous system antigens, protected against autoimmune demyelinating disease.
Resumo:
Three unlined pages with notes written by Harvard undergraduate Elijah Dunbar. The documents consist of two pages of chemistry notes compiled in September 1792 when Dunbar was a junior and an undated, untitled list of theological themes. The chemistry notes include a summary of the discipline and a set of laws regarding the "affinity of composition." The verso of the second page was later annotated: "Borrow- He that discerneth Youth & Beau[ty] Elij. Dunar 2'd 1793. Rec'd David Tappan, Professor of Divinity in the University--Elijah Dunbar, jun." followed by a list of students identified as "Alchemists" in the "Ridiculous Society": Joseph Perkins, Isaac Braman, William Biglow, and Elijah Dunbar. The second document is an untitled list of 27 theological themes beginning "1. Doctrine of the Trinity," and ending "27. Family worship," and may refer to sermon or lecture topics.
Resumo:
"Die ältesten monumente eines figurirten contrapunctes": xx p.
Resumo:
Mode of access: Internet.
Resumo:
Contiene: t. 7, 8, 9, 11, 13, 16, 18, 19, 20, 21, 23, 24, 25, 26, 27, 28, 29, 30, 31.
Resumo:
Mode of access: Internet.
Resumo:
Mode of access: Internet.
Resumo:
También editado en 2 v.
Resumo:
Mode of access: Internet.