PCR-based gene targeting of the inducible nitric oxide synthase (NOS2) locus in murine ES cells, a new and more cost-effective approach.

Gene targeting by double homologous recombination in murine embryonic stem (ES) cells is a powerful tool used to study the cellular consequences of specific genetic mutations. A typical targeting construct consists of a neomycin phosphotransferase (neo) gene flanked by genomic DNA fragments that are homologous to sequences in the target chromosomal locus. Homologous DNA fragments are typically cloned from a murine genomic DNA library.

Expression of Janus kinase 3 in human endothelial and other non-lymphoid and non-myeloid cells.

Members of the Janus kinase (Jak) family of protein tyrosine kinases have recently been implicated in the proximal signal transduction events of cytokine receptors. Jak3, a newly discovered member of this family, is believed to be normally limited in its expression to cells of the lymphoid and myeloid lineages. Herein we show that Jak3 is expressed in primary human vascular cells, as well as other non-lymphoid and non-myeloid cell types.

Coacaethylene levels in patients who test positive for cocaine.

Study Objective: To determine the presence of cocaethylene, an active metabolite of the combination of cocaine and ethanol, among trauma patients who test positive for cocaine.

Methods: We assembled a case series of 416 consecutive urban trauma center patients with major trauma. Urine was tested for the presence of the cocaine metabolite benzoylecgonine.

Association of postprandial triglyceride and retinyl palmitate responses with newly diagnosed exercise-induced myocardial ischemia in middle-aged men and women.

Although strong evidence exists linking fasting plasma levels of LDL cholesterol (LDL-C) and HDL cholesterol (HDL-C) to risk for development of coronary artery disease (CAD), the data in support of an independent role for fasting triglyceride (TG) concentrations are weak. Humans are in the postprandial state most of the day, however, and results from both basic and clinical studies suggest that postprandial TG levels may be atherogenic. Previous studies have not, however, attempted to determine if postprandial TG levels are associated with CAD independent of other traditional risk factors or plasma lipid levels, particularly fasting plasma concentrations of TG and HDL-C.

Maintained nodal-distance effects in equivalence classes.

Twelve subjects were trained to select one of two stimuli from a pair (the B pair) when presented with one of two stimuli from another pair (the A pair), thus establishing two AB relations, A1-B1 and A2-B2. In a similar fashion, additional stimuli were used to establish BC, CD, and DE relations. Trials used to train all relations occurred in each session.

Naive CD28-deficient T cells can initiate but not sustain an in vitro antigen-specific immune response.

Naive T cells require an Ag-specific signal, as well as a costimulatory signal to mount a primary Ag-specific response. Because of their low precursor frequency, it has been difficult to study costimulatory requirements of these Ag-specific T cells. We have generated a CD28-deficient mouse that has been bred to a TCR transgenic (Tg) mouse to better study the function of CD28 during CD4+ T cell responses to Ag.

Rapid development of disseminated superficial porokeratosis after transplant induction therapy.

Disseminated superficial actinic porokeratosis (DSAP) is a cutaneous disorder, usually inherited in an autosomal dominant fashion, characterized by numerous annular papules with subtle raised hyperkeratotic borders and slightly atrophic centers. While the precise pathophysiologic mechanisms underlying the development of DSAP are unknown, one hypothesis is multifocal expansion of atypical clones of keratinocytes, perhaps unmasked by actinic damage, as implied by its name. Although primarily of cosmetic concern, there is an increased risk of squamous cell carcinoma of the skin developing within DSAP lesions, which often show histologic keratinocytic atypia centrally.

Hemolytic disease of the newborn due to the Scianna antibody, anti-Sc2.

Background: Alloantibodies to the low-frequency antigen Scianna 2 (Sc2) are uncommon and not previously reported to cause immune hemolysis.

Case Report: A group B, Rh-negative infant born to a group B, Rh-positive mother had a 2+ direct antiglobulin test, as well as modest hyperbilirubinemia and a hematocrit of 45 percent. Ongoing immune hemolysis led to a hematocrit of 17.

Activity of melphalan in combination with the glutathione transferase inhibitor sulfasalazine.

Glutathione (GSH) transferases (GST), a family of detoxification enzyme proteins, are suggested to play an important role in tumor cell resistance to melphalan. The GST-activity inhibitor ethacrynic acid has been shown to increase the antitumor activity of melphalan in vitro as well as in vivo. In this study we determined the activity and toxicity of melphalan in combination with another GST-activity inhibitor, sulfasalazine, an agent used to treat ulcerative colitis.

A national survey of drug testing policies for college athletes.

This study examined current and proposed drug testing policies from a stratified random sample of colleges and universities in the United States. Two-hundred forty-five of the 288 athletic directors surveyed responded, and 29% reported drug testing of their student athletes. Testing was most commonly conducted on a random basis, with cocaine and amphetamines the most frequently screened drugs, 85% and 83%, respectively.

An examination of current and proposed drug-testing policies at US colleges and universities.

Administrators at 400 colleges and universities were surveyed for information regarding their schools' current or proposed policies for the urine drug testing of faculty, nonfaculty employees, and students. Three hundred seven schools (77%) responded regarding their testing policies for employees and applicants for employment, including faculty and nonfaculty; 332 (83%) responded with respect to students. Twenty-five schools reported testing one or more of these groups.

The use of concentration measurements of parent drug and metabolites during clinical trials.

The need for well-designed pharmacokinetic (PK) and pharmacodynamic (PD) studies early in the development of new drugs is described. In this review we illustrate the application and cost-effectiveness of optimal sampling theory in PK study design for ongoing clinical trial studies of ethyol, a chemoprotector drug. The importance of careful selection of the appropriate biological fluid in which to measure drug concentration at the earliest possible stage of new drug development is described in the context of the development of new immunosuppressive drugs.

Disappearance of the lymphoid system in Bcl-2 homozygous mutant chimeric mice.

The bcl-2 proto-oncogene can prevent the death of many cell types. Mice were generated that were chimeric for the homozygous inactivation of bcl-2. Lymphocytes without Bcl-2 differentiated into phenotypically mature cells.

Mutations of the chloramphenicol acetyl transferase transgene driven by the immunoglobulin promoter and intron enhancer.

Transgenic mice containing the chloramphenicol acetyl transferase (CAT) gene driven by the immunoglobulin (Ig) VH promoter and the heavy chain intron enhancer were prepared to increase our understanding of the mechanism responsible for somatic mutation. The transgene showed similar tissue specificity in terms of expression as endogenous Ig genes. Hybridomas were prepared after multiple immunization of a transgenic mouse with (4-hydroxy-3-nitrophenyl)acetyl-chicken gammaglobulin, a thymus-dependent antigen.

Interactions among emergent relations during equivalence class formation.

The interactions among symmetry, transitivity, and equivalence tests during the formation of 3-member equivalence classes were studied with 14 college students. After training AB and BC, a test with BA, CB, AC, and CA was conducted concurrently. Failure led to serial testing with probes for CA equivalence, BA symmetry, CA equivalence, CB symmetry, CA equivalence, AC transitivity, and CA equivalence.

Organ injury associated with extrathymic induction of immune tolerance in doubly transgenic mice.

The developmental fate of autoreactive T cells encountering extrathymically expressed self-antigen was studied in a doubly transgenic mouse model system where pancreatic acinar cells expressed H-2Ld and T cells expressed an antigen receptor (2C TCR) specific for H-2Ld. Thymocytes bearing 2C TCR differentiated normally. They were positively selected without evidence of intrathymic clonal deletion.

Stimulus generalization and equivalence classes: a model for natural categories.

Two three-member classes were formed by training AB and BC using a conditional discrimination procedure. The A and B stimuli were nonsense syllables, and the C stimuli were sets of "short" or "long" lines. To test for equivalence, C1 or C2 was presented as a sample with A1 and A2 as comparisons.

The effects of nodality on the formation of equivalence classes.

A four-member equivalence class (A----B----C----D) can be formed by training AB, BC, and CD. The nodal stimuli, B and C, mediate all of the derivative (transitive and equivalence) relations in the class. The derivative relations AC, CA, BD, and DB are separated by one node, whereas AD and DA are separated by two nodes.

Protein kinase C regulation of terminal deoxynucleotidyl transferase.

Terminal deoxynucleotidyl transferase (TdT) is a nuclear enzyme found in early lymphocytes which is thought to increase junctional diversity of TCR and Ig genes by the addition of N regions. TdT is normally found only in immature lymphoid cells and is turned off in both mature B and T cells. To investigate the regulation of TdT gene expression, pre-B and pre-T cells were treated with PMA or three of its analogs and its effects on steady-state TdT mRNA levels determined.

Carcinomas in children. Clinical and demographic characteristics.

Carcinomas occur rarely in children and adolescents. Despite their rarity, these tumors present a unique opportunity to assess theories of origin because the interval from birth to tumor onset is relatively short compared with that seen in adults. We describe the clinical and demographic characteristics of 151 patients younger than 20 years of age with carcinomas who were treated at a pediatric cancer center having a large referral area.

Exoneration of the mentally ill.

Mental illness may be manifested in the impairment of understanding or of volitional control. Impairment of understanding may be manifested in delusions. Impairment of volitional control is shown when a person is unable to act in accordance with good reasons that he himself accepts.

The structure of equivalence classes.

THE STRUCTURE OF EQUIVALENCE CLASSES CAN BE COMPLETELY DESCRIBED BY FOUR PARAMETERS: class size, number of nodes, the distribution of "singles" among nodes, and directionality of training. Class size refers to the number of stimuli in a class. Nodes are stimuli linked by training to at least two other stimuli.