A field programmable gate array based Langmuir probe system for measurement of plasma parameters at 500 kHz in a high-power impulse magnetron sputtering plasma

By utilizing Field Programmable Gate Arrays in a configuration similar to that of the Mirror Langmuir Probe, it is possible to bias a single probe at three precise voltages in sequence. These voltages can be dynamically adjusted in real-time based on the measured plasma electron temperature to ensure the transition region is always sampled. The first results have been obtained by employing this method and have generated real-time outputs of electron temperature, ion saturation current, and floating potential on a low temperature pulsed-DC magnetron at 500 kHz. These results are in good agreement with the analysis of a conventionally swept Langmuir probe. This probe is designed with the intention of being implemented on MAST-U to aid in the study of exhaust physics and enable further investigation into filamentary behavior.

Overview of the Langmuir probe system on the Mega Ampere Spherical Tokamak (MAST) Upgrade

A detailed description of the Langmuir probe system on Mega Ampere Spherical Tokamak Upgrade is presented. The system features 850 tile-embedded probes and 40 bespoke electronic modules that each have the capability to drive and acquire data from up to 16 probes in a time-multiplexed manner. The system provides spatiotemporal-resolved measurements (1 cm and ∼1 ms, respectively) in the divertor region of ion saturation current, electron temperature, and floating potential. The standard interpretation of current-voltage (IV) characteristics is to apply a four-parameter fit, based on unmagnetized probe theory, which includes a linear model for the ion saturation region. To mitigate the effect of the magnetic field, analysis is restricted to the region of the IV characteristic, which is sensitive to only the tail of the electron energy distribution function.

2D measurements of plasma electron density using coherence imaging with a pixelated phase mask

In this paper, the pixelated phase mask (PPM) method of interferometry is applied to coherence imaging (CI)-a passive, narrowband spectral imaging technique for diagnosing the edge and divertor regions of fusion plasma experiments. Compared to previous CI designs that use a linear phase mask, the PPM method allows for a higher possible spatial resolution. The PPM method is also observed to give a higher instrument contrast (analogous to a more narrow spectrometer instrument function). A single-delay PPM instrument is introduced as well as a multi-delay system that uses a combination of both pixelated and linear phase masks to encode the coherence of the observed radiation at four different interferometer delays simultaneously. The new methods are demonstrated with measurements of electron density n_e, via Stark broadening of the H_γ emission line at 434.0 nm, made on the Magnum-PSI linear plasma experiment. A comparison of the Abel-inverted multi-delay CI measurements with Thomson scattering shows agreement across the 3 × 10¹⁹ < n_e < 1 × 10²¹ m^-3 range. For the single-delay CI results, agreement is found for n_e > 1 × 10²⁰ m^-3 only. Accurate and independent interpretation of single-delay CI data at lower n_e was not possible due to Doppler broadening and continuum emission.

Development of an 11-channel multi wavelength imaging diagnostic for divertor plasmas in MAST Upgrade

Divertor detachment and alternative divertor magnetic geometries are predicted to be promising approaches to handle the power exhaust of future fusion devices. In order to understand the detachment process caused by volumetric losses in alternative divertor magnetic geometries, a Multi-Wavelength Imaging (MWI) diagnostic has recently been designed and built for the Mega Amp Spherical Tokamak Upgrade. The MWI diagnostic will simultaneously capture 11 spectrally filtered images of the visible light emitted from divertor plasmas and provide crucial knowledge for the interpretation of observations and modeling efforts. This paper presents the optical design, mechanical design, hardware, and test results of an 11-channel MWI system with a field of view of 40°. The optical design shows better than 5 mm FWHM spatial resolution at the plasma on all 11 channels across the whole field of view. The spread of angle of incidence on the surface of each filter is also analyzed to inform the bandwidth specification of the interference filters. The results of the initial laboratory tests demonstrate that a spatial resolution of better than 5 mm FWHM is achieved for all 11 channels, meeting the specifications required for accurate tomography.

MANTIS: A real-time quantitative multispectral imaging system for fusion plasmas

This work presents a novel, real-time capable, 10-channel Multispectral Advanced Narrowband Tokamak Imaging System installed on the TCV tokamak, MANTIS. Software and hardware requirements are presented together with the complete system architecture. The image quality of the system is assessed with emphasis on effects resulting from the narrowband interference filters. Some filters are found to create internal reflection images that are correlated with the filters' reflection coefficient. This was measured for selected filters where significant absorption (up to 65% within ∼70 nm of the filter center) was measured. The majority of this was attributed to the filter's design, and several filters' performance is compared. Tailored real-time algorithms exploiting the system's capabilities are presented together with benchmarks comparing polling and event based synchronization. The real-time performance is demonstrated with a density ramp discharge performed on TCV. The behavior of spectral lines' emission from different plasma species and their interpretation are qualitatively described.

Physically principled reflection models applied to filtered camera imaging inversions in metal walled fusion machines

Ray-tracing techniques are applied to filtered divertor imaging, a diagnostic that has long suffered from artifacts due to the polluting effect of reflected light in metal walled fusion machines. Physically realistic surface reflections were modeled using a Cook-Torrance micro-facet bi-directional reflection distribution function applied to a high resolution mesh of the vessel geometry. In the absence of gonioreflectometer measurements, a technique was developed to fit the free parameters of the Cook-Torrance model against images of the JET in-vessel light sources. By coupling this model with high fidelity plasma fluid simulations, photo-realistic renderings of a number of tokamak plasma emission scenarios were generated. Finally, a sensitivity matrix describing the optical coupling of a JET divertor camera and the emission profile of the plasma was obtained, including full reflection effects. These matrices are used to perform inversions on measured data and shown to reduce the level of artifacts in inverted emission profiles.

The multi-spectral imaging diagnostic

The Multi-Spectral Imaging system is a new diagnostic that captures simultaneous spectrally filtered images from a common line of sight while maintaining a large étendue and high throughput. Imaging several atomic line intensities simultaneously may enable numerous measurement techniques. By making a novel modification of a polychromator layout, the MSI sequentially filters and focuses images onto commercial CMOS cameras while exhibiting minimal vignetting and aberrations. A four-wavelength system was initially installed and tested on Alcator C-Mod and subsequently moved to TCV. The images are absolutely calibrated and spatially registered enabling 2D mappings of atomic line ratios and absolute line intensities. The spectral transmission of the optical system was calibrated using an integrating sphere of known radiance. The images are inverted by cross-referencing points on TCV with a computer-aided design (CAD) model.

Divertor impurity injection using high voltage arcs for impurity transport studies on the Mega Amp Spherical Tokamak

The operation of next-generation fusion reactors will be significantly affected by impurity transport in the scrape-off layer (SOL). Current modelling efforts are restricted by a lack of detailed data on impurity transport in the SOL. In order to address this, a carbon injector has been designed and installed on the Mega Amp Spherical Tokamak (MAST). The injector creates short lived carbon plumes originating at the MAST divertor lasting less than 50 μs. High voltage capacitor banks are used to create a discharge across concentric carbon electrodes located in a probe mounted on the Divertor Science Facility in the MAST lower divertor. This results in a very short plume duration allowing observation of the evolution of the plume and precise localisation of the plume relative to the X-point on MAST. The emission from the carbon plume was imaged using fast visible cameras filtered in order to isolate the carbon II and carbon III emission lines centered around 514 nm and 465 nm.

Coherence imaging of scrape-off-layer and divertor impurity flows in the Mega Amp Spherical Tokamak (invited)

A new coherence imaging Doppler spectroscopy diagnostic has been deployed on the UK's Mega Amp Spherical Tokamak for scrape-off-layer and divertor impurity flow measurements. The system has successfully obtained 2D images of C III, C II, and He II line-of-sight flows, in both the lower divertor and main scrape-off-layer. Flow imaging has been obtained at frame rates up to 1 kHz, with flow resolution of around 1 km/s and spatial resolution better than 1 cm, over a 40° field of view. C III data have been tomographically inverted to obtain poloidal profiles of the parallel impurity flow in the divertor under various conditions. In this paper we present the details of the instrument design, operation, calibration, and data analysis as well as a selection of flow imaging results which demonstrate the diagnostic's capabilities.

Mandibular phenotype of p20C/EBPbeta transgenic mice: Reduced alveolar bone mass and site-specific dentin dysplasia

CCAAT enhancer binding proteins (C/EBP) comprise a family of basic-leucine zipper transcription factors that regulate cellular differentiation and function. To determine the role of C/EBP transcription factors in osteoblasts and odontoblasts, we generated a transgenic (TG) mouse model with Co1a1 (pOBCol3.6) promoter-targeted expression of a FLAG-tagged dominant negative C/EBP isoform, p20C/EBPbeta (previously LIP). Two of the four transgenic lines presented with abnormalities in the developing incisors, including breakage, overgrowth, and malocclusion. Histological examination revealed that the amount of alveolar bone was reduced in TG compared to wild-type (WT) mice. By microcomputed tomography (microCT), the bone volume fraction of the mandible was reduced at the level of the first and third molars, demonstrating a severe mandibular osteopenia. The lingual dentin morphology of TG incisors differed dramatically from WT. Labial dentin (enamel side) showed normal thickness and tubular dentin structure, whereas the lingual dentin was thinner (25-30% of WT at the alveolar crest) with an amorphous globular structure characteristic of dentin dysplasia. FLAG immunostaining was seen in both lingual and labial odontoblasts, indicating that the site-specific defect was not due to a lack of labial transgene expression. Northern blot analysis demonstrated reduced osteocalcin expression in TG mandibles, while bone sialoprotein was increased, consistent with prior results in calvariae and long bones. Dental sialophosphoprotein, a marker of the odontoblast lineage whose absence causes dentin dysplasia, was modestly reduced in TG mice by Northern blot and in situ hybridization analysis. By fluorescence microscopy, pOBCol2.3-GFP, a marker of the odontoblast lineage, was expressed in both labial and lingual odontoblasts, although GFP-marked lingual odontoblasts were more flattened than WT cells. Moreover, GFP-positive processes in the lingual dentin tubules were truncated and less organized than those in WT dentin. MicroCT analysis showed reduced tissue density in the lingual dentin. These data suggest that C/EBP transcription factors may be involved in the regulation of odontoblast polarization and dentin matrix production.

Impaired cortical bone acquisition and osteoblast differentiation in mice with osteoblast-targeted disruption of glucocorticoid signaling

To determine the role of endogenous glucocorticoids in bone, we previously developed transgenic mice in which a 2.3 kb fragment of the Col1a1 promoter drives 11beta-hydroxysteroid dehydrogenase 2 expression in mature osteoblasts. This transgene should inactivate glucocorticoids upstream of all receptor signaling pathways. In the present study, we show that femoral cortical bone area and thickness were approximately 10-15% lower in transgenic mice than in wild-type littermates. Femur length was unchanged, indicating that bone elongation was not affected in this model. Expression of osteocalcin mRNA, pOBCol2.3-GFP (a green fluorescent protein marker of mature osteoblasts), and the formation of mineralized nodules were impaired in ex vivo transgenic primary calvarial cultures. The extent of crystal violet staining in bone marrow cultures, indicative of the number of adherent stromal cells, was also decreased. These data suggest that endogenous glucocorticoids are required for cortical bone acquisition and full osteoblast differentiation. It appears that blocking glucocorticoid signaling in vivo leads to a decrease in the commitment and/or expansion of progenitors entering the osteoblast lineage.

Ill-health retirement: national rates and updated guidance for occupational physicians

BACKGROUND

Advising on ill-health retirement is an important role of most practising occupational physicians. In recent years, the eligibility criteria and process for gaining early retirement benefits have changed in many pension schemes in the UK.

AIM

To investigate the variation in rates of retirement due to ill-health in National Health Service (NHS) Trusts and Local Authorities and to update previously published guidance on ill-health retirement with specific reference to pension schemes with eligibility criteria that include permanence of incapacity due to ill-health.

METHODS

Rates of retirement were calculated for 222 NHS Trusts and 132 Local Authorities with more than 1500 employees. Literature searches and consensus statements by the authors.

RESULTS

Rates of retirement were widely distributed in the NHS Trusts and Local Authorities. The median rates of retirement were 2.11 (IQR 1.37-2.91)/1000 active members and 4.10 (IQR 3.01-6.10)/1000 employees, respectively (P<0.001). Difficulties in the doctor-patient relationship and in ascertaining the true functional ability of some patients were identified.

CONCLUSION

There continues to be marked variation in rates of early retirement due to ill-health within and between organizations that warrants further investigation. The general and specific guidance that appears as an appendix in Supplementary data to this paper should help occupational physicians to make equitable recommendations when assessing applications for early retirement benefits and fitness to work.

Urine amino and organic acids analysis in developmental delay or intellectual disability

OBJECTIVES

To determine the proportion of urine amino and organic acids screening tests (UMS) undertaken for patients referred with developmental delay or intellectual disability (DD/ID), and within the group with DD/ID, to determine the diagnostic yield, the proportion of diagnoses with a therapy and the associated recurrence risks.

METHODS

A retrospective review of request forms and results of UMS, in individuals older than 28 days, referred to the Women's and Children's Hospital, North Adelaide, between 1 January 1992 and 31 December 1998 was carried out. Urine was analysed by ion exchange chromatography (amino acids), gas chromatography/mass spectrometry (organic acids), colorimetric assay (orotic acid) and stable isotope-dilution mass spectrometry (trimethylamine).

RESULTS

A total of 3316 samples were received, 1447 being from patients with DD/ID. A diagnosis was determined for 1.8% of all referrals. For patients with DD/ID, the diagnostic yield was 1.1%, with a similar yield for isolated DD/ID and DD/ID with other features (9/828 vs 7/619; chi2 = 0.006; P = 0.93). Specific therapies were available for 69% of diagnoses associated with DD/ID and 87.5% had known Mendelian or mitochondrial inheritance.

CONCLUSION

Urine metabolic screening is an important part of the evaluation of children with DD/ID as it can enable families to make reproductive decisions and children to receive appropriate therapy early.

Gastro-oesophageal reflux disease in obesity: pathophysiological and therapeutic considerations

Gastro-oesophageal reflux disease (GERD) is common in obese patients. Apart from the physical discomfort and the economic burden, GERD may increase morbidity and mortality through its association with oesophageal carcinoma. The pathophysiology of GERD differs between obese and lean subjects. First, obese subjects are more sensitive to the presence of acid in the oesophagus. Second, hiatal hernia, capable of promoting GERD by several mechanisms, is more prevalent among the obese. Third, obese subjects have increased intra-abdominal pressure that displaces the lower oesophageal sphincter and increases the gastro-oesophageal gradient. Finally, vagal abnormalities associated with obesity may cause a higher output of bile and pancreatic enzymes, which makes the refluxate more toxic to the oesophageal mucosa. The altered body composition associated with obesity affects the pharmacokinetics of drugs. There are no data regarding the efficacy of any of the drugs used for GERD treatment. The dosages of cimetidine and ranitidine should be calculated according to the patient's ideal body weight, not their actual weight. Of the operative procedures used for weight loss, Roux-en-Y gastric bypass was found to be most effective for GERD, while gastric banding was associated with a high prevalence of reflux. This review outlines the pathophysiology and the treatment of GERD in obesity with emphasis on the therapeutic considerations in this population of patients.

Chronic intermittent intestinal obstruction from a seat belt injury

Most patients with intestinal obstruction have had previous surgery. Rarely, the development of adhesions and resulting small bowel obstruction is attributed to previous intra-abdominal trauma. We present the case of a young man, without a history of surgery, who had been a restrained driver in a motor vehicle crash. Seven years later, the patient had an intermittent partial small bowel obstruction that recurred over the next 5 years. We review the pathophysiology and epidemiology of similar occurrences, as well as diagnostic options.

Hepatic angiosarcoma: an unusual cause of congestive heart failure

Hepatic angiosarcoma is a rare form of liver cancer. The history, physical examination, and liver biopsy are nonspecific. As a result, diagnosis of angiosarcoma can be challenging. We report the case of an elderly woman with congestive heart failure caused by a hepatic angiosarcoma. The massive tumor burden created extensive arteriovenous shunting and a high-cardiac-output state.

Involvement of CCAAT enhancer binding protein transcription factors in the regulation of prostaglandin G/H synthase 2 expression by interleukin-1 in osteoblastic MC3T3-E1 cells

Interleukin-1 (IL-1) stimulates prostaglandin production in bone by a rapid and transient activation of prostaglandin G/H synthase 2 (PGHS-2) gene expression. In osteoblastic MC3T3-E1 cells, IL-1 caused a transient increase in PGHS-2 messenger RNA (mRNA), which peaked at 2 h. IL-1 caused a 2- to 4-fold activation of a 371-base pair (bp) murine PGHS-2 promoter/luciferase construct in stable transfectants. This response mapped to a proximal promoter element(s) located between -150 and -40 bp. This region contains a putative CCAAT enhancer binding protein (C/EBP) site (centered at -135 bp), which shows enhanced binding of C/EBPbeta and C/EBPdelta by mobility shift analysis after IL-1 treatment. A transient cotransfection approach was used to examine the effects of C/EBPbeta and C/EBPdelta overexpression. IL-1 caused a maximal 3- to 7-fold stimulation of PGHS-2 promoter activity after 2.5 h. Overexpression of murine C/EBPbeta and C/EBPdelta caused a dose-dependent increase in basal and IL-1-stimulated luciferase activity. C/EBPdelta caused a greater enhancement of basal and IL-1-stimulated promoter activity than C/EBPbeta, suggesting that C/EBPdelta is a stronger transactivator. Overexpression of p20C/EBPbeta, a dominant negative inhibitor of C/EBP function, blocked the stimulation of PGHS-2 promoter activity by IL-1 and blocked the ability of overexpressed C/EBPbeta and C/EBPdelta to increase basal and IL-1-stimulated promoter activity. Mutagenesis of the C/EBP site reduced, but did not abolish, the stimulation of PGHS-2 promoter activity by IL-1 and blunted the effect of overexpressed C/EBPdelta on basal and IL-1-stimulated promoter activity. These results suggest an essential role for C/EBPbeta and C/EBPdelta in the induction of PGHS-2 gene expression by IL-1 in osteoblastic cells.

Treatment of late-onset nonketotic hyperglycinaemia: effectiveness of imipramine and benzoate

We report a patient with late-onset nonketotic hyperglycinaemia managed with a sequential approach to drug therapy in placebo-controlled therapeutic trials. Partial response to low-protein diet and sodium benzoate and dramatic response to imipramine are demonstrated, with parental scores on the Developmental Behavioural Checklist falling from the 86th centile before treatment to normal with combined benzoate and imipramine therapy.

Molecular modeling studies on G-quadruplex complexes of telomerase inhibitors: structure-activity relationships

Inhibition of the ability of the enzyme telomerase to add telomeric repeats to the end of chromosomes is a novel target for potential anticancer therapy. This paper examines the hypothesis that compounds possessing a planar aromatic chromophore inhibit telomerase via stabilization of, and binding to, a folded guanine quadruplex structure. Two series of telomerase inhibitors have been designed based on the 2,6-disubstituted amidoanthracene-9,10-dione and 3,6-disubstituted acridine chromophores in order to investigate structure-activity relationships between biological activity and substituent group size. The relative binding energies between these compounds and the folded human telomere DNA quadruplex were determined using molecular simulation methods, involving explicitly solvated structures. The results obtained are in excellent agreement with the biological activity as measured in vitro using a modified TRAP assay and in general agreement with the ranking order of binding enthalpies found in isothermal titration calorimetry studies. This broad agreement provides strong support for the hypothesis that guanine quadruplexes are the primary target for telomerase inhibitors with extended planar chromophores.

Multiple acyl-coenzyme A dehydrogenase deficiency: diagnosis by acyl-carnitine analysis of a 12-year-old newborn screening card

We report a family who experienced an unexplained neonatal death. Twelve years after the death, we retrospectively diagnosed multiple acyl-coenzyme A dehydrogenase deficiency by demonstrating an abnormal acyl-carnitine profile in the child's archived newborn screening card, using tandem mass spectrometry.

Parathyroid hormone induces interleukin-6 heterogeneous nuclear and messenger RNA expression in murine calvarial organ cultures

The cytokine, interleukin-6 (IL-6), is produced by osteoblasts and may in part mediate parathyroid hormone (PTH)-stimulated bone resorption. The goals of the present study were: (1) to examine PTH induction of IL-6 expression in 7-day-old mouse calvarial organ cultures; (2) to assess the role of intracellular signaling pathways in this model; and (3) to determine whether PTH regulates IL-6 expression by a transcriptional mechanism. Northern blot analysis of calvarial RNA showed that PTH(1-34) at 0.1-100 nmol/L induced IL-6 mRNA at 0.5 h with a peak at 2 h. Forskolin at 10 micromol/L and 8-bromocyclic-AMP at 3 mmol/L also induced IL-6 mRNA with a peak at 2 h. Phorbol myristate acetate induced IL-6 expression, whereas ionomycin and PTH(3-34) amide, an N-terminal-truncated PTH analog that has reduced ability to activate the cAMP-PKA pathway, were much less effective. PMA pretreatment of calvariae greatly blocked IL-6 mRNA induction by a subsequent dose of PMA and decreased induction by PTH and forskolin to a much lesser extent. A reverse-transcriptase polymerase chain reaction (RT-PCR) assay was used to measure IL-6 heterogeneous nuclear RNA (hnRNA) and mRNA. A 5' primer spanning exons 1 and 2 and a 3' primer complementary to exon 5 of the murine IL-6 gene were used to detect IL-6 mRNA as a 638 bp product. A 5' primer corresponding to intron 4 of the murine IL-6 gene and the 3' primer were used to detect IL-6 hnRNA as a 370 bp product. RT-PCR of total calvarial RNA showed that the induction of IL-6 hnRNA by PTH and other agonists was similar to their induction of IL-6 mRNA. These data support the conclusion that PTH transcriptionally induces IL-6 gene expression in murine calvarial organ cultures mainly through the cAMP-PKA signaling pathway.

Interleukin-1 represses COLIA1 promoter activity in calvarial bones of transgenic ColCAT mice in vitro and in vivo

Interleukin-1 (IL-1) inhibits collagen synthesis in osteoblastic cell lines and primary osteoblast-like cells. However, promoter elements regulating type I collagen A1 (COLIA1) expression in vivo and in organ culture may differ from those regulating expression in cell culture. We have examined the effects of IL-1 on reporter gene activity in neonatal transgenic mouse calvariae bearing COLIA1 promoter-chloramphenicol acetyltransferase (ColCAT) fusion genes. The parent construct, ColCAT 3.6, contains 3.5 kb of 5' flanking sequence and 115 bp of 5' untranslated region fused to the CAT reporter. In 48-h calvarial organ cultures, IL-1 repressed ColCAT 3.6 promoter activity and collagen synthesis in a dose-related manner, with a maximal inhibition of 40-65%. This repression was retained in 5' deletion constructs truncated to-1719 bp. The inhibition of transgene mRNA was blocked by cycloheximide, indicating a requirement for new protein synthesis. Pretreatment with indomethacin diminished the inhibitory effect of IL-1 on CAT activity and collagen synthesis, suggesting partial mediation by prostaglandins. Local in vivo injection of IL-1 (500 ng) decreased calvarial transgene mRNA after 8 h, an effect that was partially blocked by indomethacin. ColCAT transgenic mice represent a useful model for in vitro and in vivo assessment of COLIA promoter regulation by cytokines and other factors.

AccuStat whole blood fingerstick test for Helicobacter pylori infection: a reliable screening method

Helicobacter pylori antibody testing is accurate for diagnosing untreated patients. Rapid serum testing is as accurate as formal enzyme-linked immunosorbent assay (ELISA) testing. As whole blood fingerstick tests may become the diagnostic method of choice if they are of similar accuracy, 51 patients were studied who had not taken antibiotics, bismuth, sucralfate, or proton pump inhibitors. Concordance between C-14 Urea Breath Testing and HM-CAP ELISA testing served as the study standard for H. pylori diagnosis. Rapid antibody testing was performed with the AccuStat whole blood (Boehringer Mannheim, Mannheim, Germany) and FlexSure HP (Smith Kline Diagnostics, San Jose, CA) serum tests. Antral biopsy for CLO testing and histological evaluation with thiazine staining were available for 18 (35.3%) and 20 patients (39.2%), respectively. Nineteen of 50 patients (38%) were infected. (One patient had discordant tests and was excluded.) FlexSure HP and AccuStat were each positive in 18 (36%) and 19 patients (38%) with sensitivity, specificity, and positive and negative predictive values of 89.5% and 89.5%, 96.8% and 93.5%, 94.4% and 89.5%, and 93.8% and 93.5%, respectively. There were two false-negative FlexSure HP and AccuStat tests and three false-positive tests--1 FlexSure and 2 AccuStat results. CLO test and histology concurred in every case tested. We conclude that both rapid antibody tests are accurate and suitable for screening patients not previously treated for H. pylori infection. Since the AccuStat has preserved diagnostic strength, is less costly, takes less time, and is less labor intensive, whole blood testing is the screening test of choice.

Interleukin-4 inhibits prostaglandin G/H synthase-2 and cytosolic phospholipase A2 induction in neonatal mouse parietal bone cultures

We have shown previously that prostaglandin (PG) production in 7-day-old neonatal mouse calvarial cultures is regulated largely by changes in prostaglandin G/H synthase-2 (PGHS-2) expression and to a lesser extent by changes in arachidonic acid (AA) release. In this study, we examined the effects of interleukin-4 (IL-4), and its interactions with other cytokines and with parathyroid hormone (PTH), on mRNA levels of PGHS-2, PGHS-1, and cytosolic phospholipase A2 (cPLA2) and on medium protaglandin E2 (PGE2) levels in calvarial cultures. IL-1 and tumor necrosis factor-alpha (TNF-alpha), both at 1-100 ng/ml, and PTH at 0.1-10 nM increased PGHS-2 and cPLA2 mRNA and medium PGE2 levels dose-dependently after 4 h of treatment. IL-6 and IL-11 at 1-100 ng/ml did not affect mRNA or PGE2 levels. IL-4 at 1-100 ng/ml decreased PGHS-2 and cPLA2 mRNA and PGE2 levels in control as well as IL-1, TNF-alpha, and PTH-stimulated cultures. The inhibition of PGHS-2 and cPLA2 mRNA expression by IL-4 (10 ng/ml) was present at 1 h, reached a maximum at 4 h, and persisted for 24 h. The effects were maintained in the presence of cycloheximide. IL-4 also decreased PGHS-2 protein levels in control and IL-1-stimulated cultures. PGHS-1 mRNA levels were not stimulated by any of the factors studied nor inhibited by IL-4. IL-4 partially inhibited control and PTH-stimulated 45Ca release from prelabeled mouse calvariae at 4 days. However, neither the inhibition of resorption by IL-4 nor the stimulation by IL-1 and PTH were altered by indomethacin (1 microM). We conclude that (1) IL-1, TNF-alpha, and PTH, but not IL-6 nor IL-11, can increase the expression of PGHS-2, cPLA2, and PGE2 production in cultured mouse calvariae; (2) IL-4 inhibits PGE2 production in both control and stimulated calvarial cultures by inhibiting PGHS-2 and cPLA2; and (3) IL-4 has an inhibitory effect on bone resorption which is independent of PG production.

The role of prostaglandins in the regulation of bone metabolism

Prostaglandins are likely to play an important role in the physiologic and pathologic responses of skeletal tissue. They are potent agonists that can stimulate and inhibit bone resorption and formation. In vivo, the major effect of exogenous prostaglandins, particularly prostaglandin E2, is to stimulate resorption and formation. These effects appear to involve replication and differentiation of osteoclast and osteoblast precursors, and to be mediated at least in part by cyclic 3' 5' adenosine monophosphate. Prostaglandins can inhibit the activity of isolated osteoclasts, probably also by a cyclic 3' 5' adenosine monophosphate-mediated mechanism. Inhibition of collagen synthesis can be seen in cell and organ cultures and appears to be caused by a receptor selective for prostaglandins of the F series and to involve activation of protein kinase C. Prostaglandin production by bone cells is regulated highly by mechanical forces, cytokines, growth factors, and systemic hormones. Prostaglandins also can amplify their own production. Regulation is associated with marked changes in the newly described "inducible" prostaglandin G/H synthase with less effect on the constitutive enzyme. Prostaglandins also may play a role in postmenopausal bone loss because estrogen deficiency, which increases bone turnover, can increase prostaglandin production in bone.

Regulation of type I collagen gene expression in bone

The regulation of COL1A1 gene expression in bone was studied by measuring the activity of type I collagen promoter fusion genes (ColCAT) in permanently transfected osteoblastic cells and calvariae from transgenic animals. The basal activity of ColCAT fusion genes in transfected cells is mediated by DNA sequences between -3.5 to -2.3 kb while expression in vivo requires sequences between -2.3 and -1.7 kb. Parathyroid hormone, 1,25-dihydroxyvitamin D3 and interleukin-1 decrease the activity of ColCAT fusion genes in osteoblastic cells and transgenic calvariae. Because there may be differences between the expression of ColCAT fusion genes in cultured cells and intact bone, it will be important to compare data obtained from transfected cells with an in vivo model such as calvariae from transgenic mice.

Stimulation of prostaglandin E2 production by interleukin-1 alpha and transforming growth factor alpha in osteoblastic MC3T3-E1 cells

The mechanism by which interleukin-1 (IL-1) and transforming growth factor alpha (TGF-alpha) regulate prostaglandin synthesis has been examined in the clonal mouse osteoblastic cell line MC3T3-E1. Cells were grown in DMEM containing 10% fetal calf serum. Prostaglandin E2 (PGE2) production was determined by radioimmunoassay or by prelabeling cells with [3H]arachidonic acid, followed by high-performance liquid chromatography (HPLC) analysis of the labeled products released into the medium. Prostaglandin G/H synthase (PGHS) mRNAs were quantified by northern blot analysis using [32P]labeled cDNA probes. By HPLC, PGE2 was the major prostanoid produced under basal or stimulated conditions. No release of thromboxane or 6-keto-PGF1 alpha into the medium was detected. PGE2 production was stimulated approximately 7- to 14-fold by IL-1 (1 ng/ml) and 3- to 8-fold by TGF-alpha (30 ng/ml) after 24 h. In combination, however, IL-1 and TGF-alpha caused a synergistic 37- to 71-fold increase in PGE2 accumulation. PGHS-1 mRNA levels were maximally increased approximately 2- to 3-fold by IL-1 and 1.5 to 2.5-fold by TGF-alpha after 24 h; the combination of IL-1 and TGF-alpha produced only an additive 3- to 6-fold increase. Western blotting revealed a corresponding 3-fold increase in immunoreactive PGHS-1 protein in response to combined IL-1 and TGF-alpha. PGHS-2 mRNA was increased 1.4-fold by TGF-alpha at 1 h, and the combination of IL-1 and TGF-alpha caused a 1.7-fold increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Exposure to lead in stained glass work. An environmental evaluation

An environmental evaluation was conducted to determine lead exposure in a group of crafts people who produce stained glass and Tiffany glass. The environmental evaluation consisted of air sampling for potential lead emissions from solder and of work area dusts. In addition, the completion of a questionnaire, observation of work practices and noting of other details relevant to hazardous exposures were carried out. Lead concentrations in air were found to be well below the ACGIH TLV-TWA of 150 micrograms/m3. High lead concentrations were found in the work area dust samples. Exposure to high concentrations of lead could occur by ingestion as a result of neglect of basic hygiene precautions.

Plasma cis-dec-4-enoic acid measured by isotope dilution mass spectrometry; an improved assay to diagnose medium-chain acyl-CoA dehydrogenase deficiency

An isotope dilution mass spectrometric assay for plasma cis-dec-4-enoic acid is described. It is quicker, more reliable and more accurate than previous methods. It confirmed previous findings that cis-dec-4-enoic acid is a reliable indicator for medium-chain acyl-CoA dehydrogenase deficiency (MCAD). The plasma cis-dec-4-enoic acid levels of both asymptomatic and symptomatic MCAD patients (3.5-71 mumol/L) are demonstrably higher than those of normal children (0.2-1.7 mumol/L), MCAD heterozygotes (0.1-1.5 mumol/L), those with other fatty acid oxidation defects (0.2-2.2 mumol/L) or those receiving high doses of valproic acid (0.2-0.4 mumol/L).

Transgenic expression of COL1A1-chloramphenicol acetyltransferase fusion genes in bone: differential utilization of promoter elements in vivo and in cultured cells

To directly compare the patterns of collagen promoter expression in cells and tissues, the activity of COL1A1 fusion genes in calvariae of neonatal transgenic mice and in primary bone cell cultures derived by sequential digestion of transgenic calvariae was measured. ColCAT3.6 contains 3.6 kb (positions -3521 to +115) of the rat COL1A1 gene ligated to the chloramphenicol acetyltransferase (CAT) reporter gene. ColCAT2.3 and ColCAT1.7 are 5' deletion mutants which contain 2,296 and 1,672 bp, respectively, of COL1A1 DNA upstream from the transcription start site. ColCAT3.6 activity was 4- to 6-fold lower in primary bone cell cultures than in intact calvariae, while ColCAT2.3 activity was at least 100-fold lower in primary bone cells than in calvariae. These changes were accompanied by a threefold decrease in collagen synthesis and COL1A1 mRNA levels in primary bone cells compared with collagen synthesis and COL1A1 mRNA levels in freshly isolated calvariae. ColCAT3.6 and ColCAT2.3 activity was maintained in calvariae cultured in the presence or absence of serum for 4 to 7 days. Thus, when bone cells are removed from their normal microenvironment, there is parallel downregulation of collagen synthesis, collagen mRNA levels, and ColCAT3.6 activity, with a much greater decrease in ColCAT2.3. These data suggest that a 624-bp region of the COL1A1 promoter between positions -2296 and -1672 is active in intact and cultured bone but inactive in cultured cells derived from the bone. We suggest that the downregulation of COL1A1 activity in primary bone cells may be due to the loss of cell shape or to alterations in cell-cell and/or cell-matrix interactions that normally occur in intact bone.

Basic fibroblast growth factor inhibits type I collagen gene expression in osteoblastic MC3T3-E1 cells

We examined the effect of basic fibroblast growth factor (bFGF) on alpha 1(I) procollagen mRNA levels, alpha 1(I) collagen gene transcription, and alpha 1(I) collagen promoter activity in osteoblastic MC3T3-E1 cells. Cells were stably transfected with ColCAT 3.6, containing 3521 base pairs of alpha 1(I) collagen promoter DNA, fused to the CAT reporter gene, or an upstream deletion mutant of ColCAT 3.6 designated ColCAT 2.3. After 48 h, bFGF (0.1-10 nM) inhibited the incorporation of [3H]proline into collagenase-digestible protein (CDP). Indomethacin did not alter the inhibitory effect of bFGF on CDP labeling. Aphidicolin, an inhibitor of DNA synthesis, did not block the inhibitory effect of bFGF on CDP. bFGF (1-10 nM) decreased alpha 1(I) procollagen mRNA levels, with maximal inhibition, nearly 99% of control, caused by 10 nM bFGF. After 48 h, bFGF (1 nM) reduced alpha 1(I) procollagen gene transcription by about 92%. ColCAT 3.6 activity was inhibited with 0.1-10 nM bFGF and was maximally repressed by about 83% with 10 nM bFGF. In contrast, bFGF (1 and 10 nM) caused a stimulation of ColCAT 2.3 activity. These data show that bFGF inhibits collagen synthesis by a transcriptional mechanism and the alpha 1(I) collagen promoter contains DNA sequences which mediate bFGF inhibition of type I collagen gene expression in bone.

Differential utilization of regulatory domains within the alpha 1(I) collagen promoter in osseous and fibroblastic cells

Type I collagen is expressed in a variety of connective tissue cells and its transcriptional regulation is highly complex because of the influence of numerous developmental, environmental, and hormonal factors. To investigate the molecular basis for one aspect of this complex regulation, the expression of alpha 1(I) collagen (COL1A1) gene in osseous tissues, we fused a 3.6-kb DNA fragment between bases -3,521 and +115 of the rat COL1A1 promoter, and three deletion mutants, to the chloramphenicol acetyltransferase (CAT) marker gene. The expression of these ColCAT transgenes was measured in stably transfected osteoblastic cell lines ROS 17/2.8, Py-la, and MC3T3-E1 and three fibroblastic lines NIH-3T3, Rat-1, and EL2. Deletion of the distal 1.2-kb fragment of the full-length ColCAT 3.6 construct reduced the promoter activity 7- to 30-fold in the osteoblastic cell lines, twofold in EL2 and had no effect in NIH-3T3 and Rat-1 cells. To begin to assess the function of COL1A1 upstream regulatory elements in intact animals, we established transgenic mouse lines and examined the activity of the ColCAT3.6 construct in various tissues of newborn animals. The expression of this construct followed the expected distribution between the high and low collagen-producing tissues: high levels of CAT activity in calvarial bone, tooth, and tendon, a low level in skin, and no detectable activity in liver and brain. Furthermore, CAT activity in calvarial bone was three- to fourfold higher than that in the adjacent periosteal layer. Immunostaining for CAT protein in calvaria and developing tooth germ of ColCAT3.6 mice also confirmed the preferred expression of the transgene in differentiated osteoblasts and odontoblasts compared to fibroblast-like cells of periosteum and dental papilla. This study suggests that the 3.6-kb DNA fragment confers the strong expression of COL1A1 gene in high collagen producing tissues of intact animals and that the 5' flanking promoter sequence between -3,521 and -2,295 bp contains one or more stimulatory elements which are preferentially active in osteoblastic cells.

Mechanism of regulation of prostaglandin production by parathyroid hormone, interleukin-1, and cortisol in cultured mouse parietal bones

Bovine PTH-(1-34) (PTH), human recombinant interleukin-1 alpha (IL-1), and cortisol were tested for their effects on bone resorption, prostaglandin (PG) production, and PG endoperoxide synthase (PGH synthase or cyclooxygenase) mRNA levels in cultured mouse parietal bones. Cultures were treated with PTH and IL-1 in the presence and absence of cortisol and arachidonic acid (AA). We found that both PTH and IL-1 stimulated the release of PGE2 and 6-keto-PGF1 alpha (the stable metabolite of PGI2). Stimulation of each metabolite by IL-1 at 0.6-60 pM was 2- to 118-fold, and that by PTH at 24 pM to 24 nM was 3- to 53-fold. Thus, IL-1 was 40-fold more potent than PTH in stimulating PG release. Moreover, IL-1 showed 2- to 3-fold greater efficacy than PTH in stimulating PGE2 release. However, IL-1 was only 4-fold more potent and no more effective than PTH in stimulating 45Ca release. IL-1 (60 pM) and PTH (2.4 nM) stimulation of PGE2 production showed a similar time course, with a lag phase of 0.75-1.5 h. Cortisol (1-100 nM) reduced basal PGE2 production and calcium release. The absolute amounts of PG produced in response to PTH and IL-1 were reduced in the presence of cortisol, but in the presence of AA the relative increases were still from 2.5- to 26-fold compared with levels in cultures treated with cortisol alone. Cortisol reduced the stimulation of 45Ca release by IL-1, but not by PTH. AA (10(-5) M) amplified PG production in response to PTH and IL-1, but not 45Ca release. In bones labeled with [3H]AA, IL-1 and PTH increased [3H]PGE2 and [3H]6-keto-PGF1 alpha release, as measured by HPLC and TLC. IL-1 slightly increased [3H]AA release, but PTH did not. Cortisol decreased [3H]AA release. To test for an effect on PG production at the level of PGH synthase, mRNA levels were measured. mRNA was increased by both PTH and IL-1 to a similar extent despite the greater effect of IL-1 on PGE2 production. Cortisol did not change PGH synthase mRNA levels and did not block the stimulation by PTH or IL-1. We conclude that IL-1 is a more potent stimulator of PG production and bone resorption than PTH. Stimulation of PG production by both PTH and IL-1 is mediated at least in part by increasing PGH synthase, but IL-1 may have an additional effect on AA release.

Effects of transforming growth factor-beta and IL-1 alpha on prostaglandin synthesis in serum-deprived osteoblastic cells

We investigated the effects that the combination of IL-1 alpha and transforming growth factor-beta (TGF-beta) had on PGE2 production in a murine clonal osteoblastic cell line MC3T3-E1 and primary rat calvarial osteoblast-like cells. In serum-supplemented medium, IL-1 alpha was a potent stimulator of PGE2 production in MC3T3-E1 cells (50-fold increase with 0.1 ng/ml). TGF-beta (10 ng/ml) had only a small effect alone and no additional effect on IL-1 alpha-induced responses. In serum-deprived MC3T3-E1 cells, PGE2 responses to IL-1 alpha were either absent or markedly reduced. TGF-beta alone had small effects. However, simultaneous addition of TGF-beta with IL-1 alpha to MC3T3-E1 cells partially restored the ability of IL-1 alpha to generate a PGE2 response (10-fold increase in PGE2 with 0.1 ng/ml of both IL-1 alpha and TGF-beta). As with MC3T3-E1 cells, serum-deprived primary fetal rat calvarial osteoblastic cells also did not respond to IL-1 alpha, unless TGF-beta was present in the medium (sixfold increase in PGE2 with 0.1 ng/ml IL-1 alpha and 10 ng/ml TGF-beta). The synergistic effect of TGF-beta and IL-1 alpha was specific for PGE2 responses, because these factors did not synergistically affect cell proliferation, collagen and noncollagen protein synthesis, or alkaline phosphatase activity. The observed synergy was not associated with changes in the steady state cyclooxygenase (PGH synthase) mRNA levels. However, it did correlate with increased release of [3H]arachidonic acid from prelabeled serum-depleted MC3T3-E1 cells. Hence, the synergistic interactions of IL-1 alpha and TGF-beta on PGE2 appear to occur through an increase in the release of arachidonic acid substrate from phospholipid pools. These effects may be important for both normal bone turnover and the responses of bone to inflammatory and immune stimuli.

Effects of transforming growth factor-beta and IL-1 alpha on prostaglandin synthesis in serum-deprived osteoblastic cells

We investigated the effects that the combination of IL-1 alpha and transforming growth factor-beta (TGF-beta) had on PGE2 production in a murine clonal osteoblastic cell line MC3T3-E1 and primary rat calvarial osteoblast-like cells. In serum-supplemented medium, IL-1 alpha was a potent stimulator of PGE2 production in MC3T3-E1 cells (50-fold increase with 0.1 ng/ml). TGF-beta (10 ng/ml) had only a small effect alone and no additional effect on IL-1 alpha-induced responses. In serum-deprived MC3T3-E1 cells, PGE2 responses to IL-1 alpha were either absent or markedly reduced. TGF-beta alone had small effects. However, simultaneous addition of TGF-beta with IL-1 alpha to MC3T3-E1 cells partially restored the ability of IL-1 alpha to generate a PGE2 response (10-fold increase in PGE2 with 0.1 ng/ml of both IL-1 alpha and TGF-beta). As with MC3T3-E1 cells, serum-deprived primary fetal rat calvarial osteoblastic cells also did not respond to IL-1 alpha, unless TGF-beta was present in the medium (sixfold increase in PGE2 with 0.1 ng/ml IL-1 alpha and 10 ng/ml TGF-beta). The synergistic effect of TGF-beta and IL-1 alpha was specific for PGE2 responses, because these factors did not synergistically affect cell proliferation, collagen and noncollagen protein synthesis, or alkaline phosphatase activity. The observed synergy was not associated with changes in the steady state cyclooxygenase (PGH synthase) mRNA levels. However, it did correlate with increased release of [3H]arachidonic acid from prelabeled serum-depleted MC3T3-E1 cells. Hence, the synergistic interactions of IL-1 alpha and TGF-beta on PGE2 appear to occur through an increase in the release of arachidonic acid substrate from phospholipid pools. These effects may be important for both normal bone turnover and the responses of bone to inflammatory and immune stimuli.

Effects of ionizing radiation on fixed-ratio escape performance in rats

Adult male rats pressed a lever to terminate scrambled footshock according to a fixed-ratio 20 schedule (FR escape). Separate groups of rats received a single whole-body exposure to 4.5 or 7.5 Gray (Gy) of gamma photon radiation or were sham irradiated. The first postirradiation test session began 5 min after the end of the irradiation. The 4.5 Gy dose failed to produce any significant changes in performance over six weeks of testing after exposure. In contrast, response rates after irradiation with 7.5 Gy were decreased over the first four weeks postexposure. Reductions in response rate were due to both an increase in the latency to the first response of a ratio and to a reduction in running response rate. Performance recovered to preirradiation control levels during weeks 5-6 after exposure to 7.5 Gy. Body weights were decreased dose-dependently to a minimum of 91% of preirradiation control values during the third week after exposure to 7.5 Gy. A significant positive correlation existed for changes in the weekly average response rates and body weights at this dose. When a total dose of 7.5 Gy was delivered as 1.5 Gy per day for five consecutive days (dose fractionation), there were no significant changes in performance over eight weeks of testing although reversible decreases in response rates occurred in three of six rats. By comparison with previous studies these results demonstrate that FR escape performance may provide a more sensitive index of radiation-induced behavioral disruption than performance maintained by several other schedules of negative reinforcement.(ABSTRACT TRUNCATED AT 250 WORDS)

Canadian perspectives on aluminum

The multi-media approach to aluminum exposure will allow a more informed decision on the inclusion or exclusion of various exposure media in future epidemiological studies.Knowledge of the types of Al (speciation) and their respective bioavailability will enable interpretation of the importance of specific media.

Interleukin-1 alpha and phorbol ester inhibit collagen synthesis in osteoblastic MC3T3-E1 cells by a transcriptional mechanism

The effects of recombinant human interleukin-1 alpha (IL-1) on procollagen gene expression were examined in the clonal mouse osteoblastic cell line MC3T3-E1. Cells were grown in Dulbecco's Modified Eagle's Medium containing 10% fetal calf serum and 50 micrograms/ml ascorbic acid. Collagen synthesis was assessed as [3H]proline incorporation into collagenase-digestible protein (CDP). Procollagen mRNA levels were determined by Northern blot analysis using a 32P-labeled alpha 1(I) cDNA. Transcription rates were determined by nuclear run-off assay. IL-1 at 1-1000 pg/ml caused a concentration-dependent inhibition of CDP, which was maximally reduced by 75-80%, and a parallel reduction of procollagen alpha 1(I) mRNA levels. The effects of IL-1 were mimicked by the tumor promoter phorbol 12-myristate 13-acetate (PMA) at 1-100 nM, which inhibited CDP and reduced procollagen alpha 1(I) mRNA levels to a similar extent. The effects of IL-1 and PMA were independent of prostaglandin production, since indomethacin did not alter the inhibitory effect of either agent on CDP. Neither IL-1 (up to 10 ng/ml) nor PMA (100 nM) affected adenylate cyclase activity, while forskolin (10 microM), PTH (10 nM) and prostaglandin E2 (1 microM) stimulated adenylate cyclase activity 3- to 5-fold. However, forskolin (10 microM) and (Bu)2cAMP (100 microM) failed to alter CDP or procollagen alpha 1(I) mRNA levels. IL-1 (1 ng/ml) and PMA (100 nM) reduced transcription of the alpha 1(I) procollagen gene by 70% and 80%, respectively, while alpha 2(I) transcription was decreased by 59% and 53%. Neither IL-1 nor PMA affected transcription of the beta-actin or beta-tubulin genes.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of transforming growth factor alpha and interleukin-1 on DNA synthesis, collagen synthesis, procollagen mRNA levels, and prostaglandin E2 production in cultured fetal rat calvaria

Transforming growth factor alpha (TGF-alpha) and interleukin-1 (IL-1) have been shown to affect bone metabolism in vitro by prostaglandin-dependent and PG-independent mechanisms. We assessed the effects of the combination of these two agents on [3H]thymidine (TdR) incorporation into DNA, DNA content, [3H]proline incorporation into collagenase-digestible (CDP), noncollagen protein (NCP), and PGE2 production in 21 day fetal rat calvaria cultured for 24-96 h. We also determined whether TGF-alpha plus IL-1 altered procollagen mRNA levels at 96 h. TGF-alpha, 1-30 ng/ml, produced a 41-59% increase in TdR incorporation into DNA, but the effect was partially blocked by human recombinant IL-1. At 96 h TGF-alpha alone or in combination with IL-1 significantly increased the DNA content of calvaria. At 96 h, TGF-alpha inhibited CDP labeling and the addition of IL-1 further enhanced this inhibitory effect. The enhanced inhibitory effect of TGF-alpha plus IL-1 on collagen synthesis was associated with a synergistic increase in prostaglandin accumulation in the medium. Addition of indomethacin blocked PGE2 accumulation and partially reversed the inhibitory effect of TGF-alpha alone or in combination with IL-1 on collagen synthesis. TGF-alpha decreased procollagen mRNA levels by 55%, but the combination of TGF-alpha plus IL-1 decreased procollagen mRNA levels by 82%. Our results show that TGF-alpha and IL-1, which are both produced by certain tumors as well as activated macrophages, appear to act synergistically to increase prostaglandin synthesis and inhibit collagen synthesis in vitro. Thus these agents may have a regulatory role on bone formation in vivo.

1,25-Dihydroxyvitamin D3 inhibits transcription of type I collagen genes in the rat osteosarcoma cell line ROS 17/2.8

Our previous studies have demonstrated that 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3)] reduces type I collagen synthesis and steady state levels of procollagen mRNA in cultured fetal rat calvaria and rat osteosarcoma cells. To determine whether 1,25-(OH)2D3 regulates transcription of type I collagen genes, transcription rates were measured directly in nuclei isolated from ROS 17/2.8 cells using a nuclear run-off assay. Transcription was allowed to proceed in the presence of [32P]UTP for 20 min, at which time incorporation of radiolabeled UTP into trichloroacetic acid-precipitable material was maximal. UTP incorporation was inhibited 90% by 3 micrograms/ml actinomycin-D and 40% by 1 microgram/ml alpha-amanitin. Treatment of ROS 17/2.8 cells with 1,25-(OH)2D3 inhibited procollagen gene transcription in a concentration and time dependent manner. Procollagen transcription was reduced by approximately 50% of the control rate by 10 nM 1,25-(OH)2D3, and this inhibition was maximal after 24 h of 1,25-(OH)2D3 treatment. The inhibition of procollagen transcription was specific for collagen, since total RNA synthesis and beta-actin transcription were not inhibited by 1,25-(OH)2D3. The magnitude of the decrease of procollagen transcription by 1,25-(OH)2D3 was comparable to its inhibition of steady state procollagen mRNA levels, suggesting that transcription is the predominant mechanism by which 1,25-(OH)2D3 regulates collagen gene expression in bone cells.

Selective, stability-indicating assay of the major ipecacuanha alkaloids, emetine and cephaeline, in pharmaceutical preparations by high-performance liquid chromatography using spectrofluorimetric detection

A selective high-performance liquid chromatographic procedure has been developed for the determination of the major Ipecacuanha alkaloids, emetine and cephaeline, in a number of linctus and pastille preparations. The reversed-phase chromatographic procedure uses an octadecyl-bonded column with a mobile phase of aqueous methanol containing an ion-pairing reagent. A spectrofluorimetric detector is used for increased sensitivity and selectivity. Sample preparation is simple, involving either straight dilution for linctus formulations or simple dissolutions for pastilles. The procedure has been shown to be stability-indicating. Validation studies, to show that the method is precise, accurate and rectilinear, have been carried out on four linctus formulations and two pastille formulations. The method has been used to determine both emetine and cephaeline at levels as low as 5 micrograms/g in formulations.

Effects of sublethal doses of ionizing radiation on schedule-controlled performance in rats

Male rats responded under a fixed-ratio (FR) 50 or a fixed-interval (FI) 120 sec schedule of milk delivery. Separate groups were acutely exposed to 0.5, 1.5, 4.5 or 0 (FI only) Gray (Gy) of cobalt-60 gamma radiation 3 times at 43-day intervals. All rats received an acute dose of 6.5 Gy 64 days after the last of these exposures. One-half and 1.5 Gy did not alter FR or FI performance significantly. After 4.5 Gy, no observable changes in performance occurred within 1 hr of exposure. Maximal reductions in FR response rates occurred 24 hr after exposure and recovery followed over the subsequent 72 hr. Postreinforcement pause was increased and running response rate was decreased by 4.5 Gy. Similar effects were found after each 4.5 Gy exposure. In contrast, FI performance (overall response rate, postreinforcement pause, running response rate, index of curvature) was not altered reliably by 4.5 Gy. Both FR and FI response rates were reduced by 6.5 Gy beginning 24 hr after exposure; FR rates tended to be reduced more than FI rates 24-72 hr after exposure. Response rates under both schedules recovered gradually over 7 weeks. The behavioral effects of 6.5 Gy did not vary as a function of irradiation history. In contrast, irradiation history affected survival in that 4/9 rats previously exposed to 4.5 Gy died during weeks 4-5 after 6.5 Gy, whereas there were no deaths in the rats previously exposed to lower doses. Radiogenic disruption of operant performance was dose-related, reversible, noncumulative and dependent on the schedule of reinforcement.

Phorbol esters induce interleukin 2 mRNA in sensitive but not in resistant EL4 cells

Phorbol ester sensitive EL4 cells become growth-inhibited and produce interleukin 2 when treated with phorbol-12, 13-dibutyrate. Resistant cells lack both responses. To determine whether the defect in phorbol ester-resistant EL4 cells occurs pre- or post-transcriptionally, a hybridization assay for interleukin 2 mRNA was developed using two synthetic oligonucleotides complementary to mouse interleukin 2 mRNA as probes. Both probes hybridized to a 1-kilobase band in RNA from phorbol ester-treated sensitive cells. This RNA was detectable within 3 h of phorbol ester administration, and accumulation peaked by 12 h. The 1-kilobase band was induced in a concentration-dependent manner by 4-beta-phorbol-12, 13-dibutyrate but not by the inactive analog, 4-alpha-phorbol-12, 13-dibutyrate. No bands hybridizing with the interleukin 2 probe were detected in RNA isolated from unstimulated cells or from phorbol ester-resistant EL4 cells at any time up to 24 h following phorbol ester stimulation. The accumulation of the RNA in sensitive cells was blocked when the protein synthesis inhibitors, cycloheximide (75 microM) or puromycin (90 microM) were added within 1 h of the addition of phorbol ester. If cycloheximide was added 2 or more h after phorbol ester treatment, superinduction of the 1-kilobase band was observed. These results indicate that the failure of phorbol ester-resistant EL4 cells to produce interleukin 2 is due to a defect proximal to interleukin 2 transcription and that the accumulation of interleukin 2 mRNA in phorbol ester-sensitive EL4 cells requires protein synthesis.