Abstract
In the February 16 issue of Science, a 2.91 billion base pair consensus sequence of the human genome was reported. The work was the collaboration of the private corporation Celera and the United States government-funded Human Genome Project. Sequence was based on information from 21 donors of diverse ethnic background. The information covers most of the euchromatic regions of the genome and includes approximately 30,000 probable genes. Based on this information, it appears that about 75% of the genome is intergenic DNA, 24% is intronic sequence, and exons constitute only 1.1%. The complex evolutionary history of the human genome is suggested by evidence for multiple retroposition, gene duplication, and segmental duplication events. The genome sequence is available through the Web site www.celera.com.
Venter JC, et al: The sequence of the human genome. Science 291:1304–1351, 2001
A simple, reproducible, and inexpensive microdensitometry method for quantitation of immunohistochemical staining in paraffin and frozen sections has been reported. Immunohistochemistry was performed using alkaline phosphatase staining, the Vector Red substrate, methyl green or Mayer's hematoxylin as counterstain, and a permanent mounting medium. Microdensitometry was carried out using a custom filter and a standard digital imaging system. Vector Red was light stable, and measurements were linearly related to incorporated enzyme, section thickness, and color development time.
Ermert L, Hocke AC, Duncker HR, Seeger W, Ermert M: Comparison of different detection methods in quantitative microdensitometry. Am J Pathol 158:407–417, 2001
Tumor blood vessels are surrounded by a specific form of fibronectin containing an ED-B domain. European investigators created a fusion protein consisting of a fragment of an antibody against the ED-B domain and tissue factor, an activator of the clotting cascade; the fusion protein efficiently targeted tissue factor activity to tumor vasculature. A single dose of this fusion protein administered to mice bearing a variety of transplanted tumors caused selective infarction of all tumors. In 30% of the mice, tumors were cured; in remaining mice, significant reduction in tumor size occurred. These findings suggest that unique features of tumor vasculature can be exploited for therapeutic purposes.
Nilsson F, Kosmehl H, Zardi L, Neri D: Targeted delivery of tissue factor to the ED-B domain of fibronectin, a marker of angiogenesis, mediates the infarction of solid tumors in mice. Cancer Res 61:711–716, 2001
A recent clinical classification scheme divides equine sarcoids into five clinical types: occult, verrucous, fibroblastic, nodular, and mixed. Histopathologic characterization of the different sarcoid types did not reveal microscopic features sufficiently distinctive to allow correlation of microscopic and clinical findings. Two features, microscopic evidence of an increased density of dermal fibroblasts and bovine papilloama virus detectable by polymerse chain reaction, were common to all sarcoids examined.
Martens A, De Moor A, Demeulemeester J, Ducatelle R: Histopathological characteristics of five clinical types of equine sarcoid. Res Vet Sci 69:295–300, 2000
An herbal diet supplement containing natural sources of caffeine (guarana) and ephedrine (ma huang) has been implicated as the cause of toxicity in 47 dogs. Clinical signs in most dogs developed by eight hours after ingestion and included vomiting, tachycardia, hyperthermia, and agitation. In eight dogs, death due to toxicity or euthanasia ensued. Guarana/ma huang toxicity, along with toxicity due to amphetamines, pseudoephedrine, metaldehyde, strychnine, lead, nicotine, chocolate, and insecticides, should be included in the differential diagnosis when evidence of cardiac, gastrointestinal, and central nervous system stimulation is observed.
Ooms TG, Khan SA, Means C: Suspected caffeine and ephedrine toxicosis resulting from ingestion of an herbal supplement containing guarana and ma huang in dogs: 47 cases (1978–1999). J Am Vet Med Assn 218:225–229, 2001
American scientists have successfully created transmitochondrial mice by constructing female cell cybrids (ES cells electrofused to enucleated cytoplasts containing the mitochondria of interest), injecting these cybrids into blastocysts, and transplanting the resultant chimeric mice into recipient psuedopregnant mice. Donor mitochondria were obtained from brain synaptosomes; these synaptosomes were fused with L-cells that had been pre-treated with a mitochondrial poison to eliminate their own mitochondria; anucleate cytoplasts were created by centrifugation on Ficoll gradients. The mitochondria were transmitted through the female germ line in transmitochondrial mice, and mice with mutant mitochondria developed the expected type and pattern of disease. This technique will allow the routine generation of mouse models of mitochondrial disease.
Sligh JE, Levy SE, Waymire KG, Allard P, Dillehay DL, Nusinowitz, Heckenlively JR, MacGregor GR, Wallace DC: Maternal germ-line transmission of mutant mtDNAs from embryonic stem cell-derived chimeric mice. Proc Natl Acad Sci USA 97:14461–14466, 2000