Racial discrimination and depressive symptoms mediated by conversations about race among students of color

Racial discrimination is associated with adverse mental health outcomes among Students of Color. In order to address racial tensions, it is important to consider students' dialogues about race. The current study tested whether having positive and negative conversations about one's ethnic-racial group mediated the relation between racial discrimination at T1 and depressive symptoms 5 months later at T2 among 94 college Students of Color. Findings indicated that greater racial discrimination at T1 was associated with more frequent negative conversations about race at T2 (b = .38, p = .00), which was, in turn, associated with greater depressive symptoms at T2 (b = 2.73, p = .04); this pathway demonstrated significant mediation. However, positive conversations about race was not a significant mediator in this association. The current study highlights the importance of focusing on racial conversations after racial discrimination in order to minimize adverse effects on mental health among Students of Color.

Cannabinoid receptor-interacting protein 1a modulates CB1 receptor signaling and regulation

Cannabinoid CB1 receptors (CB1Rs) mediate the presynaptic effects of endocannabinoids in the central nervous system (CNS) and most behavioral effects of exogenous cannabinoids. Cannabinoid receptor-interacting protein 1a (CRIP1a) binds to the CB1R C-terminus and can attenuate constitutive CB1R-mediated inhibition of Ca(2+) channel activity. We now demonstrate cellular colocalization of CRIP1a at neuronal elements in the CNS and show that CRIP1a inhibits both constitutive and agonist-stimulated CB1R-mediated guanine nucleotide-binding regulatory protein (G-protein) activity. Stable overexpression of CRIP1a in human embryonic kidney (HEK)-293 cells stably expressing CB1Rs (CB1-HEK), or in N18TG2 cells endogenously expressing CB1Rs, decreased CB1R-mediated G-protein activation (measured by agonist-stimulated [(35)S]GTPγS (guanylyl-5'-[O-thio]-triphosphate) binding) in both cell lines and attenuated inverse agonism by rimonabant in CB1-HEK cells. Conversely, small-interfering RNA-mediated knockdown of CRIP1a in N18TG2 cells enhanced CB1R-mediated G-protein activation. These effects were not attributable to differences in CB1R expression or endocannabinoid tone because CB1R levels did not differ between cell lines varying in CRIP1a expression, and endocannabinoid levels were undetectable (CB1-HEK) or unchanged (N18TG2) by CRIP1a overexpression. In CB1-HEK cells, 4-hour pretreatment with cannabinoid agonists downregulated CB1Rs and desensitized agonist-stimulated [(35)S]GTPγS binding. CRIP1a overexpression attenuated CB1R downregulation without altering CB1R desensitization. Finally, in cultured autaptic hippocampal neurons, CRIP1a overexpression attenuated both depolarization-induced suppression of excitation and inhibition of excitatory synaptic activity induced by exogenous application of cannabinoid but not by adenosine A1 agonists. These results confirm that CRIP1a inhibits constitutive CB1R activity and demonstrate that CRIP1a can also inhibit agonist-stimulated CB1R signaling and downregulation of CB1Rs. Thus, CRIP1a appears to act as a broad negative regulator of CB1R function.

Morphine dependence in single enteric neurons from the mouse colon requires deletion of β-arrestin2

Chronic administration of morphine results in the development of tolerance to the analgesic effects and to inhibition of upper gastrointestinal motility but not to colonic motility, resulting in persistent constipation. In this study we examined the effect of chronic morphine in myenteric neurons from the adult mouse colon. Similar to the ileum, distinct neuronal populations exhibiting afterhyperpolarization (AHP)-positive and AHP-negative neurons were identified in the colon. Acute morphine (3 μM) decreased the number of action potentials, and increased the threshold for action potential generation indicative of reduced excitability in AHP-positive neurons. In neurons from the ileum of mice that were rendered antinociceptive tolerant by morphine-pellet implantation for 5 days, the opioid antagonist naloxone precipitated withdrawal as evidenced by increased neuronal excitability. Overnight incubation of ileum neurons with morphine also resulted in enhanced excitability to naloxone. Colonic neurons exposed to long-term morphine, remained unresponsive to naloxone suggesting that precipitated withdrawal does not occur in colonic neurons. However, morphine-treated colonic neurons from β-arrestin2 knockout mice demonstrated increased excitability upon treatment with naloxone as assessed by change in rheobase, number of action potentials and input resistance. These data suggest that similar to the ileum, acute exposure to morphine in colonic neurons results in reduced excitability due to inhibition of sodium currents. However, unlike the ileum, dependence to chronic exposure of morphine develops in colonic neurons from the β-arrestin2 knockout mice. These studies corroborate the in-vivo findings of the differential role of neuronal β-arrestin2 in the development of morphine tolerance/dependence in the ileum and colon.

An in-vitro preparation of isolated enteric neurons and glia from the myenteric plexus of the adult mouse

The enteric nervous system is a vast network of neurons and glia running the length of the gastrointestinal tract that functionally controls gastrointestinal motility. A procedure for the isolation and culture of a mixed population of neurons and glia from the myenteric plexus is described. The primary cultures can be maintained for over 7 days, with connections developing among the neurons and glia. The longitudinal muscle strip with the attached myenteric plexus is stripped from the underlying circular muscle of the mouse ileum or colon and subjected to enzymatic digestion. In sterile conditions, the isolated neuronal and glia population are preserved within the pellet following centrifugation and plated on coverslips. Within 24-48 hr, neurite outgrowth occurs and neurons can be identified by pan-neuronal markers. After two days in culture, isolated neurons fire action potentials as observed by patch clamp studies. Furthermore, enteric glia can also be identified by GFAP staining. A network of neurons and glia in close apposition forms within 5-7 days. Enteric neurons can be individually and directly studied using methods such as immunohistochemistry, electrophysiology, calcium imaging, and single-cell PCR. Furthermore, this procedure can be performed in genetically modified animals. This methodology is simple to perform and inexpensive. Overall, this protocol exposes the components of the enteric nervous system in an easily manipulated manner so that we may better discover the functionality of the ENS in normal and disease states.

Morphine decreases enteric neuron excitability via inhibition of sodium channels

Gastrointestinal peristalsis is significantly dependent on the enteric nervous system. Constipation due to reduced peristalsis is a major side-effect of morphine, which limits the chronic usefulness of this excellent pain reliever in man. The ionic basis for the inhibition of enteric neuron excitability by morphine is not well characterized as previous studies have mainly utilized microelectrode recordings from whole mount myenteric plexus preparations in guinea pigs. Here we have developed a Swiss-Webster mouse myenteric neuron culture and examined their electrophysiological properties by patch-clamp techniques and determined the mechanism for morphine-induced decrease in neuronal excitability. Isolated neurons in culture were confirmed by immunostaining with pan-neuronal marker, β-III tubulin and two populations were identified by calbindin and calretinin staining. Distinct neuronal populations were further identified based on the presence and absence of an afterhyperpolarization (AHP). Cells with AHP expressed greater density of sodium currents. Morphine (3 µM) significantly reduced the amplitude of the action potential, increased the threshold for spike generation but did not alter the resting membrane potential. The decrease in excitability resulted from inhibition of sodium currents. In the presence of morphine, the steady-state voltage dependence of Na channels was shifted to the left with almost 50% of channels unavailable for activation from hyperpolarized potentials. During prolonged exposure to morphine (two hours), action potentials recovered, indicative of the development of tolerance in single enteric neurons. These results demonstrate the feasibility of isolating mouse myenteric neurons and establish sodium channel inhibition as a mechanism for morphine-induced decrease in neuronal excitability.

The role of β-arrestin2 in the mechanism of morphine tolerance in the mouse and guinea pig gastrointestinal tract

β-Arrestin2 has been reported to play an essential role in analgesic tolerance. Analgesic tolerance without concomitant tolerance to constipation is a limiting side effect of chronic morphine treatment. Because tolerance to morphine develops in the mouse ileum but not the colon, we therefore examined whether the role of β-arrestin2 in the mechanism of morphine tolerance differs in the ileum and colon. In both guinea pig and mouse, chronic in vitro exposure (2 h, 10 μM) to morphine resulted in tolerance development in the isolated ileum but not the colon. The IC(50) values for morphine-induced inhibition of electrical field stimulation contraction of guinea pig longitudinal muscle myenteric plexus shifted rightward in the ileum from 5.7 ± 0.08 (n = 9) to 5.45 ± 0.09 (n = 6) (p < 0.001) after morphine exposure. A significant shift was not observed in the colon. Similar differential tolerance was seen between the mouse ileum and the colon. However, tolerance developed in the colon from β-arrestin2 knockout mice. β-Arrestin2 and extracellular signal-regulated kinase 1/2 expression levels were determined further by Western blot analyses in guinea pig longitudinal muscle myenteric plexus. A time-dependent decrease in the expression of β-arrestin2 and extracellular signal-regulated kinase 1/2 occurred in the ileum but not the colon after 2 h of morphine (10 μM) exposure. Naloxone prevented the decrease in β-arrestin2. In the isolated ileum from guinea pigs chronically treated in vivo with morphine for 7 days, neither additional tolerance to in vitro exposure of morphine nor a decrease in β-arrestin2 occurred. We conclude that a decrease in β-arrestin2 is associated with tolerance development to morphine in the gastrointestinal tract.

Cannabinoid CB1 receptor-interacting proteins: novel targets for central nervous system drug discovery?

The main pharmacological effects of marijuana, as well as synthetic and endogenous cannabinoids, are mediated through G-protein-coupled receptors (GPCRs), including CB(1) and CB(2) receptors. The CB(1) receptor is the major cannabinoid receptor in the central nervous system and has gained increasing interest as a target for drug discovery for treatment of nausea, cachexia, obesity, pain, spasticity, neurodegenerative diseases and mood and substance abuse disorders. Evidence has accumulated to suggest that CB(1) receptors, like other GPCRs, interact with and are regulated by several other proteins beyond the established role of heterotrimeric G-proteins. These proteins, which include the GPCR kinases, beta-arrestins, GPCR-associated sorting proteins, factor associated with neutral sphingomyelinase, other GPCRs (heterodimerization) and the novel cannabinoid receptor-interacting proteins: CRIP(1a/b), are thought to play important roles in the regulation of intracellular trafficking, desensitization, down-regulation, signal transduction and constitutive activity of CB(1) receptors. This review examines CB(1) receptor-interacting proteins, including heterotrimeric G-proteins, but with particular emphasis on non-G-protein entities, that might comprise the CB(1) receptosomal complex. The evidence for direct interaction with CB(1) receptors and potential functional roles of these interacting proteins is discussed, as are future directions and challenges in this field with an emphasis on the possibility of eventually targeting these proteins for drug discovery.

FAAH-/- mice display differential tolerance, dependence, and cannabinoid receptor adaptation after delta 9-tetrahydrocannabinol and anandamide administration

Repeated administration of Delta(9)-tetrahydrocannabinol (THC), the primary psychoactive constituent of Cannabis sativa, induces profound tolerance that correlates with desensitization and downregulation of CB(1) cannabinoid receptors in the CNS. However, the consequences of repeated administration of the endocannabinoid N-arachidonoyl ethanolamine (anandamide, AEA) on cannabinoid receptor regulation are unclear because of its rapid metabolism by fatty acid amide hydrolase (FAAH). FAAH(-/-) mice dosed subchronically with equi-active maximally effective doses of AEA or THC displayed greater rightward shifts in THC dose-effect curves for antinociception, catalepsy, and hypothermia than in AEA dose-effect curves. Subchronic THC significantly attenuated agonist-stimulated [(35)S]GTP gamma S binding in brain and spinal cord, and reduced [(3)H]WIN55,212-2 binding in brain. Interestingly, AEA-treated FAAH(-/-) mice showed less CB(1) receptor downregulation and desensitization than THC-treated mice. Experiments examining tolerance and cross-tolerance indicated that the behavioral effects of THC, a low efficacy CB(1) receptor agonist, were more sensitive to receptor loss than those of AEA, a higher efficacy agonist, suggesting that the expression of tolerance was more affected by the intrinsic activity of the ligand at testing than during subchronic treatment. In addition, the CB(1) receptor antagonist, rimonabant, precipitated a markedly reduced magnitude of withdrawal in FAAH(-/-) mice treated subchronically with AEA compared with mice treated repeatedly with THC. The findings that repeated AEA administration produces lesser adaptive changes at the CB(1) receptor and has reduced dependence liability compared with THC suggest that pharmacotherapies targeting endocannabinoid catabolic enzymes are less likely to promote tolerance and dependence than direct acting CB(1) receptor agonists.

HIV seropositive in pregnant South African women who initially refuse routine antenatal HIV screening

This study was instituted primarily to determine the HIV seroprevalence of pregnant South African women who refused routine HIV testing at the antenatal clinic of the Johannesburg Hospital, South Africa. Fifty such patients were identified, who, after being fully counselled and informed, agreed to participate in the study, provided total anonymity was adhered to: they did not want to know their results, irrespective of outcome. Blood specimens were given a laboratory reference number only, with no other reference to the patient and analysed utilising the ELISA immunoassay. Twenty-two of the 50 blood specimens, or 44% of patients analysed, tested positive for HIV. This is an alarming statistic, as the HIV prevalence in the general antenatal population at the Johannesburg Hospital is 29.4%.

A review of subtyping in autism and proposed dimensional classification model

Autism has been divided into subtypes based on social interaction/communication, developmental level, or both. The validity of subtyping systems and the extent to which they overlap were examined. According to this review, a single subtyping system capable of accounting for the symptom heterogeneity in autism has not yet been proposed; however, evidence supports the presence of a three-factor continuum containing at least four subgroups. Foremost among directions for future research is the need for comprehensive studies in which medical screening, careful selection of measures, and longitudinal data collection are included.

Management strategies to decrease the prevalence of mastitis caused by one strain of Staphylococcus aureus in a dairy herd

The dairy herd at Washington State University had an outbreak of mastitis caused by a single strain of Staphylococcus aureus. The outbreak strain, termed novel, could not be controlled with routine contagious mastitis pathogen control procedures (incidence, 3.4 infections/100 cow months; peak prevalence > 22%). Our objective was to implement mastitis control measures that would decrease the incidence and prevalence of intramammary infection (IMI) caused by S aureus in the herd. The following intervention strategies were successfully implemented: strict segregation of cattle with IMI caused by S aureus, intensified culling of cattle with multiple-quarter IMI caused by S aureus, and inducing cessation of lactation of infected quarters in single-mammary-quarter infected cattle. One year after implementation of these control measures, incidence of IMI caused by S aureus was 0.35 infections/100 cow months, and prevalence had decreased from 20 to 8%.

HC-Pro suppression of transgene silencing eliminates the small RNAs but not transgene methylation or the mobile signal

Post-transcriptional gene silencing (PTGS) is a sequence-specific RNA degradation mechanism that is widespread in eukaryotic organisms. It is often associated with methylation of the transcribed region of the silenced gene and with accumulation of small RNAs (21 to 25 nucleotides) homologous to the silenced gene. In plants, PTGS can be triggered locally and then spread throughout the organism via a mobile signal that can cross a graft junction. Previously, we showed that the helper component-proteinase (HC-Pro) of plant potyviruses suppresses PTGS. Here, we report that plants in which PTGS has been suppressed by HC-Pro fail to accumulate the small RNAs associated with silencing. However, the transgene locus of these plants remains methylated. Grafting experiments indicate that HC-Pro prevents the plant from responding to the mobile silencing signal but does not eliminate its ability to produce or send the signal. These results demonstrate that HC-Pro functions downstream of transgene methylation and the mobile signal at a step preceding accumulation of the small RNAs.

Primary mucinous adenocarcinoma of the vagina

OBJECTIVE

Our goal was to report the management and symptoms of a patient who presented with primary mucinous adenocarcinoma of the vagina with an unusual histologic pattern.

METHODS

Our methods included a retrospective description of the management, a review of the literature, and critical evaluation of the treatment modalities available for this very uncommon tumor.

RESULTS

Initially posterior partial vaginectomy and abdominoperineal resection was performed with the creation of a permanent colostomy. A bilateral inguinal lymphadenopathy was performed 6 months later on the basis of a palpable enlarged lymph node. Radiotherapy was instituted thereafter. The patient remains disease-free 48 months after initial surgery and is satisfied with her quality of life.

CONCLUSIONS

Primary mucinous adenocarcinoma of the vagina is a very rare tumor. Therefore individualized treatment is justified until larger series have been published.

Tubular carcinoma of the breast: prognosis and response to adjuvant systemic therapy

BACKGROUND

Tubular carcinoma of the breast is an uncommon and usually small tumour, and is thought to have a favourable prognosis. The present study examined the long-term prognosis of patients with tubular breast carcinoma and the roles of axillary dissection and adjuvant therapy.

METHODS

Eighty-six tubular cases were identified from a large worldwide database of 9520 breast carcinoma patients entered into randomized adjuvant therapy trials run by the International Breast Cancer Study Group from 1978 to 1999. These patients were followed for a median of 12 years.

RESULTS

Forty-two (49%) cases were node-positive, of which 33 (79%) had 1-3 nodes involved. Ten (32%) of the 31 smaller tumours (< or = 1 cm in size) were node-positive. Patients with node-positive tubular carcinoma had a significantly better 10-year relapse-free survival (P = 0.006) and survival (P < 0.0001) compared with non-tubular node-positive cases. Overall survival was similar for node-positive and node-negative tubular carcinoma. Overall, 71 patients (83%) received some form of adjuvant systemic therapy. Of the 86 cases, 43 (50%) received more than one course of chemotherapy. There was an 85% decrease in the risk of death for patients who received more than one course of chemotherapy compared to those who did not (hazard ratio 0.15, 95% confidence interval (CI): 0.03-0.82; P = 0.03).

CONCLUSIONS

Compared to other histological types of breast cancer, tubular carcinoma has a better long-term prognosis. Adjuvant chemotherapy may further improve prognosis and involvement of axillary nodes may not be an indicator for early death due to breast carcinoma.

RNA viruses as inducers, suppressors and targets of post-transcriptional gene silencing

Post-transcriptional gene silencing (PTGS) is a fundamental regulatory mechanism operating in diverse types of organisms, but the cellular components of the gene silencing machinery and the regulation of the process are not understood. Recent findings that cytoplasmically replicating RNA viruses act as both targets and inducers of PTGS has led to the idea that PTGS may have evolved as an anti-viral defense mechanism in plants. Consistent with this hypothesis, it has been found that certain plant viruses encode proteins that suppress PTGS. From a practical standpoint, an understanding of the mechanisms by which viruses regulate PTGS may well lead to better ways to control gene expression in plants. It is often desirable to overexpress selected beneficial genes or to silence detrimental ones in order to confer a particular phenotype. Induction of PTGS using RNA viruses as vectors or as transgenes provides a reliable and efficient way to interfere with the expression of a specific gene or with a family of genes. Conversely, expression of viral suppressors has significant potential to improve yields in technologies that use plants to express beneficial gene products. Given the antiviral nature of gene silencing in plants and the indications that PTGS is an ancient mechanism in eukaryotic organisms, understanding the phenomenon in plants could well lead to the development of anti-viral strategies in both plants and animals.

Plant viral suppressors of post-transcriptional silencing do not suppress transcriptional silencing

Homology-dependent gene silencing is a regulatory mechanism that limits RNA accumulation from affected loci either by suppression of transcription (transcriptional gene silencing, TGS) or by activation of a sequence-specific RNA degradation process (post-transcriptional gene silencing, PTGS). The P1/HC-Pro sequence of plant potyviruses and the 2b gene of the cucumber mosaic virus have been shown to interfere with PTGS. The ability of these viral suppressors of PTGS to interfere with TGS was tested using the 271 locus which imposes TGS on transgenes under 35S or 19S promoters and PTGS on the endogenous nitrite reductase gene (Nii). Both P1/HC-Pro and 2b reversed PTGS of Nii genes in 271-containing tobacco plants, but failed to reverse TGS of 35S-GUS transgenes in the same plant. P1/HC-Pro expression from a transgene also failed to suppress either the initiation or maintenance of TGS imposed by the NOSpro-silencing locus, H2. These results indicate that PTGS and TGS operate through unlinked pathways or that P1/HC-Pro and 2b interfere at step(s) in PTGS that are downstream of any common components in the two pathways. The data suggest a simple assay to identify post-transcriptionally silenced transgenic lines with the potential to be stably converted to high expressing lines.

A left atrial myxoma presenting as a cerebrovascular accident

A 14-year-old female presented with common clinical findings for a rare primary intracardiac tumor. Primary cardiac tumors are rare in all age groups, occurring in 0.05% of routine postmortem examinations. Pediatric primary cardiac tumors are likewise uncommon, with the most common being a rhabdomyoma. Atrial myxomas occur infrequently in the pediatric age group. They occur primarily between the third and sixth decade, making them the most common adult primary cardiac tumor. The following case presentation demonstrates a common clinical presentation for an intracardiac mass rarely diagnosed in the pediatric population. This patient's acute neurologic symptoms required prompt recognition of an intracardiac etiology. This recognition proved critical for the acute and long-term medical and surgical management of this patient.

Bifunctional phosphoramidite reagents for the introduction of histidyl and dihistidyl residues into oligonucleotides

The synthesis and characterization of reagents for the incorporation of histidyl residues into oligonucleotides by automated chemical synthesis is described. Automated oligonucleotide synthesis utilizing a bifunctional reagent for the incorporation of a dihistidyl residue into oligonucleotides is described. Oligonucleotides incorporating one to three dihistidyl residues were prepared and characterized. The interaction of these oligonucleotides with a metal chelating IMAC matrix was explored.

A viral suppressor of gene silencing in plants

Gene silencing is an important but little understood regulatory mechanism in plants. Here we report that a viral sequence, initially identified as a mediator of synergistic viral disease, acts to suppress the establishment of both transgene-induced and virus-induced posttranscriptional gene silencing. The viral suppressor of silencing comprises the 5'-proximal region of the tobacco etch potyviral genomic RNA encoding P1, helper component-proteinase (HC-Pro) and a small part of P3, and is termed the P1/HC-Pro sequence. A reversal of silencing assay was used to assess the effect of the P1/HC-Pro sequence on transgenic tobacco plants (line T4) that are posttranscriptionally silenced for the uidA reporter gene. Silencing was lifted in offspring of T4 crosses with four independent transgenic lines expressing P1/HC-Pro, but not in offspring of control crosses. Viral vectors were used to assess the effect of P1/HC-Pro expression on virus-induced gene silencing (VIGS). The ability of a potato virus X vector expressing green fluorescent protein to induce silencing of a green fluorescent protein transgene was eliminated or greatly reduced when P1/HC-Pro was expressed from the same vector or from coinfecting potato virus X vectors. Expression of the HC-Pro coding sequence alone was sufficient to suppress virus-induced gene silencing, and the HC-Pro protein product was required for the suppression. This discovery points to the role of gene silencing as a natural antiviral defense system in plants and offers different approaches to elucidate the molecular basis of gene silencing.

Cleavage susceptibility of reovirus attachment protein sigma1 during proteolytic disassembly of virions is determined by a sequence polymorphism in the sigma1 neck

A requisite step in reovirus infection of the murine intestine is proteolysis of outer-capsid proteins to yield infectious subvirion particles (ISVPs). When converted to ISVPs by intestinal proteases, virions of reovirus strain type 3 Dearing (T3D) lose 90% of their original infectivity due to cleavage of viral attachment protein sigma1. In an analysis of eight field isolate strains of type 3 reovirus, we identified one additional strain, type 3 clone 31 (T3C31), that loses infectivity and undergoes sigma1 cleavage upon conversion of virions to ISVPs. We examined the sigma1 deduced amino acid sequences of T3D and the eight field isolate strains for a correlation between sequence variability and sigma1 cleavage. The sigma1 proteins of T3D and T3C31 contain a threonine at amino acid position 249, whereas an isoleucine occurs at this position in the sigma1 proteins of the remaining strains. Thr249 occupies the d position of a heptad repeat motif predicted to stabilize sigma1 oligomers through alpha-helical coiled-coil interactions. This region of sequence comprises a portion of the fibrous tail domain of sigma1 known as the neck. Substitution of Thr249 with isoleucine or leucine resulted in resistance to cleavage by trypsin, whereas replacement with asparagine did not affect cleavage susceptibility. These results demonstrate that amino acid position 249 is an independent determinant of T3D sigma1 cleavage susceptibility and that an intact heptad repeat is required to confer cleavage resistance. We performed amino-terminal sequence analysis on the sigma1 cleavage product released during trypsin treatment of T3D virions to generate ISVPs and found that trypsin cleaves sigma1 after Arg245. Thus, the sequence polymorphism at position 249 controls cleavage at a nearby site in the neck region. The relevance of these results to reovirus infection in vivo was assessed by treating virions with the contents of a murine intestinal wash under conditions that result in generation of ISVPs. The pattern of sigma1 cleavage susceptibility generated by using purified protease was reproduced in assays using the intestinal wash. These results provide a mechanistic explanation for sigma1 cleavage during exposure of virions to intestinal proteases and may account for certain strain-dependent patterns of reovirus pathogenesis.

Outbreak of mastitis caused by one strain of Staphylococcus aureus in a closed dairy herd

The Washington State University dairy experienced an outbreak of intramammary infections (IMI) caused by Staphylococcus aureus during autumn 1993 through summer 1995. The outbreak was believed to be a result of transmission of 1 strain of S aureus in a herd that historically had excellent control of contagious mastitis. Control practices included strict hygiene at time of milking and preferential culling of cows infected with S aureus. Mastitis caused by Streptococcus agalactiae was not found in this herd. Despite excellent control practices, the strain of S aureus caused a new infection rate of approximately 3% of the herd per month. Moreover, a second strain of S aureus, isolated from a cow with mastitis, was introduced into the herd experimentally, and it failed to transmit disease. The outbreak of S aureus mastitis in this herd was eventually controlled by maintaining a program of strict milking time hygiene, by intensifying the program of preferentially culling infected cows, and by segregating cows with S aureus IMI in a separate pen and milking these infected cows last.

A cationic lipid for rapid and efficient delivery of plasmid DNA into mammalian cells

Cationic lipids are widely used for gene transfer into cultured eukaryotic cells. However, lipids with potent transfection activity are often associated with high levels of cytotoxicity, and also require serum-free conditions for optimal performance. These characteristics in many cases result in unsatisfactory transfection efficiency. In this report, we describe a new cationic amphiphile, N-t-butyl-N'-tetradecyl-3-tetradecylaminopropionamidine (Amidine). Amidine requires only 1-2 hour incubation intervals to produce maximal transfection efficiency, and can transfect cells in the presence of serum. Such characteristics significantly minimize cytotoxicity, and also provide time flexibility for researchers. We routinely obtain over 80% transfection efficiency as evidenced by use of an enhanced green fluorescence protein (EGFP) as the reporter. These studies demonstrate the utility of Amidine for rapid and efficient transfection of mammalian cells.

Rainbow Universal CPG: a versatile solid support for oligonucleotide synthesis

We have developed a universal solid support, termed Rainbow Universal CPG, for use in automated oligonucleotide synthesis. The universal solid support allows any oligodeoxyribonucleotide sequence to be synthesized from a single type of controlled pore glass (CPG) support. Deprotection of oligodeoxyribonucleotides was optimized using 0.5 M LiCl in concentrated ammonium hydroxide. PCR experiments using three different sets of primers proved that the 3'-hydroxyl function of oligodeoxyribonucleotides synthesized from Rainbow Universal CPG was retained. This universal solid support shows promise for replacing the standard nucleoside CPG supports.

Somite subdomains, muscle cell origins, and the four muscle regulatory factor proteins

We show by immunohistology that distinct expression patterns of the four muscle regulatory factor (MRF) proteins identify subdomains of mouse somites. Myf-5 and MyoD are, at specific stages, each expressed in both myotome and dermatome cells. Myf-5 expression is initially restricted to dorsal cells in all somites, as is MyoD expression in neck somites. In trunk somites, however, MyoD is initially expressed in ventral cells. Myogenin and MRF4 are restricted to myotome cells, though the MRF4-expressing cells are initially less widely distributed than the myogenin-expressing cells, which are at all stages found throughout the myotome. All somitic myocytes express one or more MRFs. The transiently distinct expression patterns of the four MRF proteins identify dorsal and ventral subdomains of somites, and suggest that skeletal muscle cells in somites originate at multiple sites and via multiple molecular pathways.

Cellular and molecular diversity in skeletal muscle development: news from in vitro and in vivo

Skeletal muscle formation is studied in vitro with myogenic cell lines and primary muscle cell cultures, and in vivo with embryos of several species. We review several of the notable advances obtained from studies of cultured cells, including the recognition of myoblast diversity, isolation of the MyoD family of muscle regulatory factors, and identification of promoter elements required for muscle-specific gene expression. These studies have led to the ideas that myoblast diversity underlies the formation of the multiple types of fast and slow muscle fibers, and that myogenesis is controlled by a combination of ubiquitous and muscle-specific transcriptional regulators that may be different for each gene. We further review some unexpected results that have been obtained when ideas from work in culture have been tested in developing animals. The studies in vivo point to additional molecular and cellular mechanisms that regulate muscle formation in the animal.

A unique pattern of expression of the four muscle regulatory factor proteins distinguishes somitic from embryonic, fetal and newborn mouse myogenic cells

A unique pattern of expression of the four muscle regulatory factor (MRF) proteins was found to distinguish early somitic from embryonic, fetal and newborn limb myogenic cells in vitro. Expression of the myosin heavy chain (MHC), MyoD, myogenin, Myf-5, and MRF4 proteins was examined by immunocytochemistry in cultures of four distinct types of mouse myogenic cells: somitic (E8.5), embryonic (E11.5), fetal (E16.5) and newborn limb. In embryonic, fetal and newborn cultures, the MRF proteins were expressed in generally similar patterns: MyoD was the first MRF expressed; MyoD and myogenin were expressed by more cells than Myf-5 or MRF4; and each of the four MRFs was found both in cells that expressed MHC and in cells that did not express MHC. In cultures of somitic cells, in contrast, Myf-5 was expressed first and by more cells than MyoD or myogenin; MRF4 was not detected; and the MRFs were never found to be coexpressed with MHC in the same cell. Thus, some somitic cells had the unexpected ability to maintain MHC expression in the absence of detectable MRF protein expression. The different myogenic programs of embryonic, fetal and newborn myogenic cells are not, therefore, a simple result of qualitatively different MRF expression patterns, whereas myogenesis by somitic cells does include a unique pattern of MRF expression.

Pulmonary metastases in children and young adults with differentiated thyroid cancer

BACKGROUND

The prognostic significance and optimal care of children with differentiated thyroid cancer and pulmonary metastases are not well established.

METHODS

Of 209 patients younger than 25 years of age who were treated at University of Texas M. D. Anderson Cancer Center between 1960 and 1990 and for whom there was sufficient information, 19 (9%) had pulmonary metastases at presentation.

RESULTS

All of these patients had regional lymphadenopathy at the time of diagnosis. All but two had intense, diffuse radioiodine uptake in the lungs; there were two false-negative scans immediately after surgical procedure caused by competing thyroid residual. The chest radiograph (CXR) was normal in 8 of 17 (42%) patients with abnormal radioiodine scans. After therapy with radioiodine (100-499 mCi), CXR appeared normal in 7 of 9 patients with initial abnormal radiographs (within 6-75 months). Radioiodine uptake by the lungs normalized in 3 of 8 patients with initially normal radiographs, and in 3 of 9 patients with initially abnormal radiographs. There have been no deaths in these 19 patients.

CONCLUSION

Pulmonary metastases are not uncommon in children and young adults with differentiated thyroid cancer, especially those who have regional lymphadenopathy. The lung metastases almost always concentrate radioiodine diffusely and may be associated with a normal CXR in almost half of the patients. Pulmonary metastases may be overlooked unless near total thyroidectomy is followed by total body radioiodine scan (TBS) in all children and young adults who have regional lymphadenopathy of the neck.

Looking back and looking forward

'Forty years back and forty years on' was the title of the address given by Francis Manfield at the annual meeting of the RCS of England in December 1970. Francis, twice president of the Middx & Herts Branch, which this year celebrates its first 40 years, started in practice in 1930, so he was well qualified to look back over those 40 years. The aspects of change in dentistry, 1930-1970, make arresting reading more than 20 years later. His predictions for the future are equally interesting.

Distinct myogenic programs of embryonic and fetal mouse muscle cells: expression of the perinatal myosin heavy chain isoform in vitro

Early embryonic and late fetal mouse myogenic cells showed distinct patterns of perinatal myosin heavy chain (MHC) isoform expression upon differentiation in vitro. In cultures of somite or limb muscle cells isolated from Day 9 to Day 12 embryos, differentiated cells that expressed perinatal MHC were rare and perinatal MHC was not detectable by immunoblotting. In cultures of limb muscle cells isolated from Day 13 to Day 18 fetuses, in contrast, the perinatal MHC isoform was easily detected and was expressed in a substantial percentage of myocytes and myotubes. Analyses of clonally derived muscle colonies and cytosine arabinoside-treated fetal muscle cell cultures suggested that different fetal muscle cell nuclei initiated perinatal MHC expression at different times. In both embryonic and fetal cell cultures, the embryonic MHC isoform was expressed by all differentiated cells examined. A small number of myotubes in fetal muscle cell cultures showed a mosaic distribution of MHC isoform accumulation in which the perinatal MHC isoform accumulated in a restricted region of the myotube near particular nuclei, whereas the embryonic MHC isoform accumulated throughout the myotube. Thus, the myogenic program of fetal, but not embryonic, mouse myogenic cells includes expression of the perinatal MHC isoform upon differentiation in culture.

Seatbelt induced chance fracture in an infant. Case report and literature review

Chance ("seat belt") fractures of the lumbar spine are extremely rare in the pediatric population and virtually unheard of in infants. We report a case of a 14 month old boy sustaining an isolated Chance fracture to L1 without associated spinal subluxation, dislocation, neurologic or visceral injury. He was being breast fed with his back beneath the passenger side shoulder harness when the vehicular front end collision causing his injury occurred. Thus, he may actually have sustained a hyperextension distraction or "Reverse Chance" fracture.

Wolf syndrome

Since the initial description in 1965 of Wolf syndrome, or deletion of the short arm of chromosome number four, over one hundred cases have been reported. Much less, however, has been published on the radiologic findings in this disorder. We report a case with both typical and unusual features of the 4p- syndrome, including "bottle opener" deformity of the clavicles, and review the relevant literature.

Imaging artifacts in mechanically driven ultrasound catheters

Mechanically driven catheter tip echo systems presently operate with a flexible shaft. Rotation power from a proximally mounted motor is transferred via this shaft to the rotating echo tip element. In practice, the tip does not identically 'follow' the rotation of the motor due to low torsional rigidity of the shaft, which creates artifacts in the displayed cross-sectional image. In order to visualize curved arteries such as the coronary arteries, a compromise is necessary between the required low flexural rigidity and a high torsional rigidity. In this report the image artifacts of mechanically driven systems are presented that are related to catheter tip motion. The properties of a spiral drive-shaft and a solid drive-shaft have been compared for rotational speed of 1000 and 3000 revolutions per minute (rpm), and for straight as well as strongly curved catheters. By way of example, the periodic angle error varies from 25 degrees top-top in a straight catheter to 80 degrees top-top when the catheter is curved with R = 20 mm, using a spiral drive-shaft at 1000 rpm.

Biochemical deficiencies of coenzyme Q10 in HIV-infection and exploratory treatment

AIDS patients (2 groups) had a blood deficiency (p less than 0.001) of coenzyme Q10 vs. 2 control groups. AIDS patients had a greater deficiency (p less than 0.01) than ARC patients. ARC patients had a deficiency (p less than 0.05) vs. control. HIV-infected patients had a deficiency (p less than 0.05) vs. control. The deficiency of CoQ10 increased with the increased severity of the disease, i.e., from HIV positive (no symptoms) to ARC (constitutional symptoms, no opportunistic infection or tumor) to AIDS (HIV infection, opportunistic infection and/or tumor). This deficiency, a decade of data on CoQ10 on the immune system, on IgG levels, on hematological activity constituted the rationale for treatment with CoQ10 of 7 patients with AIDS or ARC. One was lost to follow-up; one expired after stopping CoQ10; 5 survived, were symptomatically improved with no opportunistic infection after 4-7 months. In spite of poor compliance of 5/7 patients, the treatment was very encouraging and at times even striking.

Infected bile lakes following pediatric liver transplantation: nonsurgical management

Infected bile lakes complicated orthotopic liver transplantation in two pediatric patients. Retransplantation was avoided by means of percutaneous transhepatic internal drainage of the bile lakes. Internal drainage maintained the enterohepatic cycle of cyclosporine and allowed the bile ducts to heal.

Bilateral posterior choanal atresia: a morphologic and histologic study, and computed tomographic correlation

Bilateral posterior choanal atresia is an uncommon cause of respiratory obstruction in the newborn. Although the clinical syndrome and treatment options are well known, the abnormal histology has not been well described. Computed tomography (CT) is a useful tool in the radiologic diagnosis of choanal atresia, but has not been correlated with the histopathology. Two patients with CHARGE association (congenital heart defects, choanal atresia, retarded growth and development, hypogenitalism, and aural anomalies) and bilateral posterior choanal atresia were studied with CT. The atresia plates were removed at autopsy and sectioned in an axial plane for gross and microscopic study. The histopathology is described and correlated with the CT studies. These studies show that CT accurately defines the histopathologic abnormalities found in bilateral posterior choanal atresia.

N-(2-hydroxyethyl)doxorubicin from hydrolysis of 3'-deamino-3'-(3-cyano-4-morpholinyl)doxorubicin

The susceptibility of 3'-deamino-3'-(3-cyano-4-morpholinyl)doxorubicin to hydrolysis at pH 7, 4, and 2 has been compared with that of the typically stable morpholine analogue. At pH 7, 74% of the cyanomorpholine was unchanged after 24 h at room temperature, but at pH 2 only 10% remained. Products identified were aglycon (8%) and N-(2-hydroxyethyl)doxorubicin (7%). Most of the losses were to unidentified polar products not eluted from HPLC. Authentic hydroxyethyl was synthesized from doxorubicin by reductive alkylation with glycolaldehyde. Antitumor potency was comparable to that of doxorubicin rather than of cyanomorpholine.

Renal cystic disease in childhood

The authors present a comprehensive review of the diagnostic features of eight forms of renal cystic disease that occur in childhood. Sonographic findings are emphasized.

Spontaneous occurrence of localized pulmonary interstitial and endolymphatic emphysema in infancy

Two infants are described with persistent pulmonary interstitial and endolymphatic emphysema of the localized, bullous type, occurring apparently spontaneously. Roentgenographically, the process simulated congenital lobar emphysema in the first patient and bilateral post-infectious pneumatoceles in the second. The histologic features of the lesion were identical to those seen in localized pulmonary interstitial emphysema caused by positive pressure ventilation in newborns with hyaline membrane disease.

Antimicrobial activities of daunorubicin and adriamycin derivatives on bacterial and protoplast type L-form cells of Bacillus subtilis 170, Escherichia coli B, and Proteus mirabilis VI. Structure--activity relationship

The antibacterial activity of ten N-alkylated derivatives of daunorubicin and adriamycin as well as of 5-iminodaunorubicin has been tested by using Bacillus subtilis 170, Escherichia coli B, and Proteus mirabilis VI and their stable protoplast type L-forms in an agar diffusion test. Eight of the substances showed similar activities against B. subtilis and the L-forms of all test organisms, but no activity against the bacterial forms of E. coli and P. mirabilis. The cell wall of these gram-negative bacteria is responsible for this resistance by not allowing the antibiotics to enter the cells. The piperidino compound N-(CH2)5 daunorubicin shows 2-4 times higher activity against B. subtilis and all L-forms in comparison to daunorubicin and the other derivatives. Five of the substances were inactive against all test strains. Their inactivity seems to be associated with the larger substituents at the C-3' position. Relations between molecular structure and activity are discussed considering data about the interaction with DNA and the antitumor activity. Stable protoplast type L-forms and their bacterial forms represent a suitable and effective test system to screen for more effective substances and to get more information about their mode of action.