Epidermal growth factor receptor is not required for human cytomegalovirus entry or signaling.

Human cytomegalovirus (HCMV) can bind, fuse, and initiate gene expression in a diverse range of vertebrate cell types. This broad cellular tropism suggests that multiple receptors and/or universally distributed receptors mediate HCMV entry. Our laboratory has recently discovered that certain beta1 and beta3 integrin heterodimers are critical mediators of HCMV entry into permissive fibroblasts (A.

Myotonic dystrophy: the role of the CUG triplet repeats in splicing of a novel DMPK exon and altered cytoplasmic DMPK mRNA isoform ratios.

The mechanism by which (CTG)n expansion in the 3' UTR of the DMPK gene causes myotonic dystrophy (DM) is unknown. We identified four RNA splicing factors--hnRNP C, U2AF (U2 auxiliary factor), PTB (polypyrimidine tract binding protein), and PSF (PTB associated splicing factor)--that bind to two short regions 3' of the (CUG)n, and found a novel 3' DMPK exon resulting in an mRNA lacking the repeats. We propose that the (CUG)n is an essential cis acting element for this splicing event.

Probing the salmeterol binding site on the beta 2-adrenergic receptor using a novel photoaffinity ligand, [(125)I]iodoazidosalmeterol.

Salmeterol is a long-acting beta2-adrenergic receptor (beta 2AR) agonist used clinically to treat asthma. In addition to binding at the active agonist site, it has been proposed that salmeterol also binds with very high affinity at a second site, termed the "exosite", and that this exosite contributes to the long duration of action of salmeterol. To determine the position of the phenyl ring of the aralkyloxyalkyl side chain of salmeterol in the beta 2AR binding site, we designed and synthesized the agonist photoaffinity label [(125)I]iodoazidosalmeterol ([125I]IAS).

Developmental potency of the murine allantois.

The murine allantois is the future umbilical component of the placenta. The base of the allantois is also thought to contain the future germ line. We have examined the fate and developmental potency of cells within the murine allantois during gastrulation.

Control of cholesterol access to cytochrome P450scc in rat adrenal cells mediated by regulation of the steroidogenic acute regulatory protein.

Cholesterol conversion to pregnenolone by cytochrome P450scc in steroidogenic cells, including those of the adrenal cortex, is determined by hormonal control of cholesterol availability. Intramitochondrial cholesterol movement to P450scc, which retains hormonal activation in isolated mitochondria, is apparently dependent on peripheral benzodiazepine receptor and the recently cloned steroidogenic acute regulatory (StAR) protein. In rat adrenal cells, StAR is formed as a 37-kDa precursor that is transferred to the mitochondrial inner membrane following phosphorylation by hormonally activated protein kinase A, and processed to multiple forms, some of which turn over very rapidly.

Potassium currents expressed from Drosophila and mouse eag cDNAs in Xenopus oocytes.

The ether-a-go-go (eag) gene family encodes a set of related ion channel polypeptides expressed in the excitable cells of organisms ranging from invertebrates to mammals. Earlier studies demonstrated that eag mutations in Drosophila cause an increase in membrane excitability in the nervous system. Mutations in the human eag-related gene (HERG) have been implicated in cardiac arrhythmia, and recent studies show that HERG subunits contribute to the channels mediating IKr and the terminal repolarization of the cardiac action potential.

Battling against host phagocytes: the wherefore of the RTX family of toxins?

The RTX family of bacterial exotoxins is a group of related cytolytic proteins produced by a wide variety of gram-negative human and animal pathogens. While diverse in their associated diseases and in their target cell specificities, there remain several themes common to RTX toxins, including genetic organization, structural and functional features, and effects on target cells. In this review, we summarize and discuss the genetics, regulation, epidemiology, structure/function relationships, and in vivo and in vitro activities of the best characterized RTX toxins, and speculate on their roles in pathogenesis and their use in immunotherapy.

An E-box-mediated increase in cad transcription at the G1/S-phase boundary is suppressed by inhibitory c-Myc mutants.

To better understand the signaling pathways which lead to DNA synthesis in mammalian cells, we have studied the transcriptional activation of genes needed during the S phase of the cell cycle. Transcription of the gene encoding a pyrimidine biosynthetic enzyme, carbamoyl-phosphate synthase (glutamine-hydrolyzing)/aspartate carbamoyltransferase/dihydroorotase (cad), increases at the G1/S-phase boundary. We have mapped the growth-dependent response element in the hamster cad gene to the extended palindromic E-box sequence, CCACGTGG, which is centered at +65 in the 5' untranslated sequence.

The effect of viral inoculum level and host age on disease incidence, disease severity, and mortality in a murine model of ocular HSV-1 infection.

It has been previously shown that the strain of virus, immune competence of the host, and innate resistance of the host have an effect on the severity of ocular disease induced by topical infection with herpes simplex virus type 1 (HSV-1). This study has expanded on earlier work by examining the effect of virus inoculum and host age on mortality, incidence of ocular disease, and severity of ocular disease. BALB/c mice were infected with inocula ranging from 2 x 10(3) to 1 x 10(6) pfu of HSV-1 strain CJ394.

Persistent and relapsing infections associated with small-colony variants of Staphylococcus aureus.

Small-colony variants (SCVs) of Staphylococcus aureus were cultured from five patients with persistent and relapsing infections. All five SCV strains were nonhemolytic and nonpigmented and grew very slowly on routine culture media in an ambient atmosphere. In several instances, these phenotypic characteristics led to the initial misidentification of the organisms in the clinical microbiology laboratory.

Graduate medical education reform. Service provision transition costs.

Objective: To analyze the potential strategies and costs of house staff substitution under a reformed system of graduate medical education.

Design: An economic model using two scenarios for substitution of house staff (residents and fellows): (1) a lower-cost model under which nonphysician providers assume many house staff responsibilities, but additional aspects of their workload are taken over by staff physicians, nurses, and ancillary personnel; and (2) a higher-cost traditional model that relies more heavily on staff physicians to replace house officers.

Setting: US teaching hospitals.

Effects of trazodone and desipramine on motor recovery in brain-injured rats.

Rats pretrained to walk a narrow balance beam received unilateral sensorimotor cortex lesions, resulting in a contralateral transient paresis that lasted 14 days. In a dose-dependent manner, a single injection of the antidepressant trazodone given 24 hours after injury transiently slowed motor recovery compared with injured controls. After final recovery level of motor function, a reinjection of trazodone reinstated the hemiparesis for up to 6 hours.

Reestablishment of cell polarity of rat hepatocytes in primary culture.

The cell-basement membrane interaction is an important determinant of epithelial cell polarity. Although hepatocytes in situ are polarized, no morphologically identifiable basement membrane is found at their basal surface. However, several studies have demonstrated immunoreactivity to basement membrane proteins in the space of Disse, indicating the existence of an extracellular matrix, albeit of low density.

IFN-gamma-mediated antimicrobial response. Indoleamine 2,3-dioxygenase-deficient mutant host cells no longer inhibit intracellular Chlamydia spp. or Toxoplasma growth.

The role of indoleamine 2,3-dioxygenase (IDO) in IFN-gamma-mediated inhibition of intracellular parasite growth has been examined previously, although earlier work has been largely correlative. In this study, we defined more completely the role of IDO in the IFN-antimicrobial response. Two mutant cell lines, derived from ME180 cells and exhibiting reduced IDO activity (IR3B6A, IR3B6B) were characterized to determine if they retained the capacity to inhibit intracellular Chlamydia and Toxoplasma growth.

An immortalized human fibroblast cell line is permissive for human cytomegalovirus infection.

Human foreskin fibroblasts (HFF) were immortalized via retrovirus-mediated gene transfer of the E6 and E7 genes of human papillomavirus type 16. An immortalized fibroblast (IF) cell line which was morphologically akin to the parental cell line was isolated. The IF cell line was evaluated for permissiveness to human cytomegalovirus (HCMV) infection after the IF cell line surpassed the normal passage limitation of diploid fibroblasts.

Spinal shock: possible role of receptor plasticity and non synaptic transmission.

Spinal shock remains an enigma. To date there has been no convincing explanation of the recovery of reflexes following their complete abolition. Volume transmission includes both the activation of extrasynaptic receptors, and activity induced by substances diffusing into synaptic clefts via the extracellular fluid.

Examination of the eyelid closure defect in trisomy 16 mice.

A characteristic feature of trisomy 16 mouse conceptuses is a failure of their eyelids to close. This defect was investigated by examining ocular development in serially sectioned heads of trisomy 16 and normal littermate fetuses from 10 to 18 gestational days. Other heads were examined by using scanning electron microscopy.

Lack of detectable blood groups in domestic ferrets: implications for transfusion.

Evidence of blood groups in domestic ferrets was sought by testing serum samples for naturally acquired or experimentally induced erythrocyte antibodies. All sera were tested for ability to cause direct agglutination, antiglobulin-enhanced (Coombs test) agglutination, or lysis. Examination of 212 randomly paired combinations of ferret serum and erythrocytes produced no evidence of naturally acquired blood group antibodies.