Distinct cellular origin and genetic requirement of Hedgehog-Gli in postnatal rhabdomyosarcoma genesis.

Dysregulation of the Hedgehog (Hh)-Gli signaling pathway is implicated in a variety of human cancers, including basal cell carcinoma (BCC), medulloblastoma (MB) and embryonal rhabdhomyosarcoma (eRMS), three principle tumors associated with human Gorlin syndrome. However, the cells of origin of these tumors, including eRMS, remain poorly understood. In this study, we explore the cell populations that give rise to Hh-related tumors by specifically activating Smoothened (Smo) in both Hh-producing and -responsive cell lineages in postnatal mice. Interestingly, we find that unlike BCC and MB, eRMS originates from the stem/progenitor populations that do not normally receive active Hh signaling. Furthermore, we find that the myogenic lineage in postnatal mice is largely Hh quiescent and that Pax7-expressing muscle satellite cells are not able to give rise to eRMS upon Smo or Gli1/2 overactivation in vivo, suggesting that Hh-induced skeletal muscle eRMS arises from Hh/Gli quiescent non-myogenic cells. In addition, using the Gli1 null allele and a Gli3 repressor allele, we reveal a specific genetic requirement for Gli proteins in Hh-induced eRMS formation and provide molecular evidence for the involvement of Sox4/11 in eRMS cell survival and differentiation.

Diagnosis of a left coronary artery to right ventricular fistula with progression to spontaneous closure.

Coronary artery fistulas in structurally normal hearts are rare. The natural history of these lesions depends on their size and can cause congestive heart failure, infective endocarditis, ischemia, or accelerated atherosclerosis. These fistulas are usually closed either in the catheterization laboratory or surgically. This case demonstrates the prenatal diagnosis of a left coronary to right ventricular fistula and documents its natural history to spontaneous closure by 1 year of age. This may help confirm the rationale of observation rather than closure of small fistulas in selected cases of patients without symptoms.

The contributions of GluR2 to allosteric modulation of AMPA receptors.

Native AMPA receptor complexes in the CNS are composed of hetero-oligomers of the GluR1-4 subunits, and generally contain the GluR2 subunit. To determine the contributions of GluR2 to pharmacological properties of receptor complexes, the effect of hetero-oligomerization with GluR2 on allosteric modulation of recombinant AMPA receptors was studied. The study of homo-oligomeric GluR2 was facilitated with a site-directed mutant of the pore, GluR2(R607Q), which allowed robust currents from this normally low-conducting subunit. The efficacy of the allosteric modulators was tested on homo-oligomeric GluR1-4, and then compared with hetero-oligomeric GluR1/GluR2, GluR3/GluR2 and GluR4/GluR2. Two selective allosteric modulators were tested, a positive modulator, cyclothiazide, and a negative modulator, LY300164. The results show that the pharmacological properties of homo-oligomeric GluR2 are not significantly different from those of GluR1, GluR3 or GluR4. The apparent affinity of cyclothiazide is not significantly changed upon hetero-oligomerization. However, the extent of potentiation of kainate responses by cyclothiazide is significantly decreased upon hetero-oligomerization. Hetero-oligomerization increases the apparent affinity of LY300164, a (-) isomer of the 2,3-benzodiazepine LY293606. These data indicate that although GluR2 has a dominant effect on the permeation properties, this subunit does not have a similarly dominant effect on pharmacological properties of native receptors. However, the state of hetero-oligomerization can alter the pharmacological properties of AMPA receptors.

Mentor functions and outcomes: a comparison of men and women in formal and informal mentoring relationships.

The authors examined the effects of the type of mentoring relationship and the gender composition of the relationship on mentoring functions and career outcomes reported by 352 female and 257 male protégés. Protégés of informal mentors viewed their mentors as more effective and received greater compensation than protégés of formal mentors. Protégés with informal mentors also received more career outcomes than nonmentored individuals, but no significant differences were found between nonmentored and formally mentored individuals. The gender composition of the relationship affected mentoring functions and outcomes, and protégé gender interacted with the type of relationship to affect mentoring functions.

Cloning of tropomyosins from lobster (Homarus americanus) striated muscles: fast and slow isoforms may be generated from the same transcript.

Complementary DNAs encoding fibre-type-specific isoforms of tropomyosin (Tm) have been isolated from lobster (Homarus americanus) striated muscle expression libraries made from poly(A)+ RNA purified from deep abdominal (fast-type) and crusher-claw closer (slow-type) muscles. A cDNA of slow-muscle Tm (sTm1), containing a complete open reading frame (ORF) and portions of the 5' and 3' untranslated regions (UTRs), encodes a protein of 284 amino acid residues with a predicted mass of 32,950, assuming acetylation of the amino terminus. The nucleotide sequence of a fast-muscle tropomyosin (fTm cDNA), which includes the entire ORF and part of the 3' UTR, is identical to that of sTm1 cDNA, except in the region encoding amino acid residues 39-80 (equivalent to exon 2 of mammalian and Drosophila muscle tropomyosin genes). The deduced amino acid sequences, which display the heptameric repeats of nonpolar and charged amino acids characteristic of alpha-helical coiled-coils, are highly homologous to tropomyosins from rabbit, Drosophila, and shrimp (57% to 99% identities, depending on species). Northern blot analysis showed that two transcripts (1.1 and 2.1 kb) are present in both fibre types. Mass spectrometry indicated that fast muscle contains one major isoform (fTm: 32,903), while slow muscle contains two major isoforms (sTm1 and sTm2: 32,950 and 32,884 respectively). Both Tm preparations contained minor species with a mass of about 32,830. Sequences of peptides derived from purified slow and fast Tms were identical to the deduced amino acid sequences of the sTm1 and fTm cDNAs, respectively, except in the C-terminal region of fTm. The difference in mass between that predicted by the deduced sequence (32,880) and that measured by mass spectrometry (32,903) suggests that fTm is posttranslationally modified, in addition to acetylation of the N-terminal methionine. These data are consistent with the hypothesis that the fTm and sTm1 are generated by alternative splicing of two mutually-exclusive exons near the 5' end of the same gene.

Does employee involvement work? Yes, sometimes.

Employee involvement per se is not always effective for improving performance and/or employee attitudes. Rather, there are several different forms of employee involvement, some of which are effective, while others are not. This article describes seven forms of employee involvement, giving examples, and summarizes research findings for each form, concluding with a summary of which are the best and which are worst. This article also describes what is necessary for effective employee involvement, focusing on management commitment and training for both management and employees.

Cloning of a crustacean myosin heavy chain isoform: exclusive expression in fast muscle.

A clone of a fast isoform of myosin heavy chain (HC) gene was isolated from a cDNA1 expression library made from mRNA purified from the deep abdominal flexor muscle of the lobster, Homarus americanus. The cDNA (1.5 kb) contained the 3' untranslated region (UTR) and the coding sequence for the last 413 amino acid residues of the carboxyl terminus of the polypeptide. The deduced amino acid sequence showed high homology with that of myosin HCs from Drosophila (73% identity), nematode (57% identity), and vertebrates (49% identities). Hydropathy plots showed a 28-amino acid periodicity that is consistent with the alpha-helical coiled coil structure of the rod region of native myosin. Northern blot analysis and in situ hybridization showed that the fast myosin HC isoform was expressed only in fast fibers; the probes did not hybridize to mRNA from slow fibers. The message consisted of a single transcript of 6.6 kb. The intracellular localization of the fast myosin mRNA was not uniform. The mRNA was largely confined to the intermyofibrillar spaces and to the subsarcolemmal cytoplasm of the fiber periphery and large infoldings of the cell membrane. Within these regions the mRNA was concentrated in the cytoplasm immediately surrounding the nuclei. This constitutes the first report of the cloning and expression of a myosin HC gene from a crustacean species.

Cardiac tumors and the nevoid basal cell carcinoma syndrome.

Nevoid basal cell carcinoma syndrome is a multisystem disease with a wide range of initial symptoms that can be seen at any age. The most characteristic features are vertebral or rib anomalies, intracranial falx calcification, multiple basal cell carcinomas, odontogenic keratocysts of the jaw, and palmar and/or plantar pits. Pediatricians need to be aware that if any one of these major anomalies is seen, this diagnosis should be considered. There now appears to be an established association between cardiac tumors and nevoid basal cell carcinoma syndrome. Primary cardiac tumors have been associated with cerebral tuberous sclerosis and neurofibromatosis, and evaluation of cardiac status is recommended when these genetically determined syndromes are diagnosed. This communication should serve to alert pediatricians to the need for complete cardiac evaluation and genetic counseling when a diagnosis of nevoid basal cell carcinoma is made.

Atenolol therapy for exercise-induced hypertension after aortic coarctation repair.

After successful repair of coarctation of the aorta in childhood, exercise-induced upper body systolic hypertension is well documented. Beta blockade has been shown to reduce the arm/leg gradient in untreated coarctation of the aorta; treatment before coarctation repair has decreased paradoxical hypertension after repair. Ten patients with successful surgical repair of coarctation, defined as a resting arm/leg gradient of less than or equal to 18 mm Hg, were evaluated by treadmill exercise before and after beta blockade with atenolol. Mean age was 5.5 years at repair and 18 at study. At baseline evaluation, systolic blood pressures at termination of exercise ranged from 201 to 270 mm Hg (mean 229 mm Hg). Arm/leg gradients at exercise termination ranged from 30 to 143 mm Hg (mean 84). Follow-up treadmill exercise studies were performed after beta blockade. Upper extremity systolic pressures at exercise termination were normalized in 9 of 10 patients. Maximal systolic blood pressure recorded at exercise termination ranged from 163 to 223 mm Hg (mean 196 mm Hg, p less than or equal to 0.005). Arm/leg gradient at termination of exercise also decreased significantly to a mean of 51 mm Hg (p less than 0.05). No patient had symptoms on atenolol and exercise endurance times were unchanged. The study results in this small series suggest that cardioselective beta blockade can be used to treat exercise-induced upper body hypertension effectively after surgical repair of coarctation. Because a high incidence of premature cardiovascular disease has been well documented after satisfactory surgical repair, the findings are of importance for this group of postoperative patients.

Down-regulation of phytochrome mRNA abundance by red light and benzyladenine in etiolated cucumber cotyledons.

Northern blot analysis revealed that a single 4.2 kb phytochrome mRNA species was detectable in cotyledons excised from five-day-old etiolated cucumber seedlings. Intact etiolated five-day-old cucumber seedlings were given a red light or benzyladenine treatment, and cotyledons were harvested at various times following treatment. The abundance of phytochrome mRNA in the cotyledons was quantitated using 32P-labeled RNA probes and slot blot analysis. By 2 h after irradiation the phytochrome mRNA level was reduced to 40% of the initial abundance and reaccumulation began by 3 h after irradiation. Reaccumulation of phytochrome mRNA to the time-zero dark control level was achieved by 10 h after treatment. A decrease in phytochrome mRNA abundance was evident by 2 h after benzyladenine treatment, and a maximal reduction to 45% of the time-zero dark control was attained by 4 h after treatment. No recovery of the phytochrome mRNA level was evident by 8 h after benzyladenine treatment. The abundance of actin mRNA was unaffected by benzyladenine treatment.

Evaluation of a proprietary broth medium for microdilution susceptibility testing of nutritionally fastidious bacteria.

For microdilution susceptibility tests with nutritionally fastidious microorganisms, a new clear broth medium developed at Micro-Media Systems, Inc., Potomac, Md., was evaluated in a three-laboratory collaborative study. Replicate tests were performed with 80 isolates (51 Streptococcus spp., 27 Haemophilus influenzae isolates, and 2 Neisseria meningitidis isolates) against 15 antimicrobial agents. In standard 100-microliters volumes, results of tests in the new broth medium were comparable to those in the reference medium (Mueller-Hinton broth with 2 to 3% lysed horse blood), but MICs were somewhat easier to read in the new broth medium. Results of similar tests in smaller panels, containing 40 microliters in each well, were less satisfactory; i.e., growth failures and poorly defined endpoints were more commonly encountered. With drugs other than erythromycin or clindamycin, the 40-microliters panels provided MICs which compared favorably with those obtained by standard reference methods.

Collaborative evaluation of the micro-media systems anaerobe susceptibility panel: comparisons with reference methods and test reproducibility.

The Micro-Media Systems (MMS) anaerobe susceptibility testing panel results from four laboratories were compared for interlaboratory and intralaboratory variations and for the results with the reference agar dilution and a broth microdilution method. The interlaboratory agreement was 98.0% and intralaboratory agreement was 97.3% (+/- 1 log2 dilution). When interpretive criteria for each antimicrobial agent (susceptible, intermediate, and resistant) were assigned, the MMS anaerobic minimum inhibitory concentration data showed an interpretive accuracy of 91.0 and 95.5% for comparisons to the reference agar dilution and the broth methods, respectively. Most significant interpretive errors were considered minor, and nearly half of all errors involved tetracycline, a drug rarely used for serious anaerobic infections. The MMS anaerobe panels appear to be acceptable for selected use in clinical microbiology laboratories.

Virus-like particles in winter vomiting disease.

In an outbreak of winter vomiting disease affecting both pupils and staff in a primary school, virus-like particles were found in 7 out of 8 faecal specimens examined by electron microscopy. The particles measured 26 nm in diameter and had a buoyant density of 1-38--1-40 g/cm3 in caesium chloride. They could not be cultured in tissue-culture or organ-culture. In immune electron microscopy tests the particles appeared to differ antigenically from the Norwalk and Hawaii agents. Two out of three patients examined more than one month after their illness were still excreting the particles.