Ligand-based G Protein Coupled Receptor pharmacophore modeling: Assessing the role of ligand function in model development

Integral membrane proteins in the G Protein-Coupled Receptor (GPCR) class are attractive drug development targets. However, computational methods applicable to ligand discovery for many GPCR targets are restricted by limited numbers of known ligands. Pharmacophore models can be developed using variously sized training sets and applied in database mining to prioritize candidate ligands for subsequent validation. This in silico study assessed the impact of key pharmacophore modeling decisions that arise when known ligand numbers for a target of interest are low. GPCR included in this study are the adrenergic alpha-1A, 1D and 2A, adrenergic beta 2 and 3, kappa, delta and mu opioid, serotonin 1A and 2A, and the muscarinic 1 and 2 receptors, all of which have rich ligand data sets suitable to assess the performance of protocols intended for application to GPCR with limited ligand data availability. Impact of ligand function, potency and structural diversity in training set selection was assessed to define when pharmacophore modeling targeting GPCR with limited known ligands becomes viable. Pharmacophore elements and pharmacophore model selection criteria were also assessed. Pharmacophore model assessment was based on percent pharmacophore model generation failure, as well as Güner-Henry enrichment and goodness-of-hit scores. Three of seven pharmacophore element schemes evaluated in MOE 2018.0101, Unified, PCHD, and CHD, showed substantially lower failure rates and higher enrichment scores than the others. Enrichment and GH scores were used to compare construction protocol for pharmacophore models of varying purposes- such as function specific versus nonspecific ligand identification. Notably, pharmacophore models constructed from ligands of mixed functions (agonists and antagonists) were capable of enriching hitlists with active compounds, and therefore can be used when available sets of known ligands are limited in number.

Measuring functional brain recovery in regenerating planarians by assessing the behavioral response to the cholinergic compound cytisine

Planarians are traditional model invertebrates in regeneration and developmental biology research that also display a variety of quantifiable behaviors useful to screen for pharmacologically active compounds. One such behavior is the expression of seizure-like movements (pSLMs) induced by a variety of substances. Previous work from our laboratory showed that cocaine, but not nicotine, induced pSLMs in intact but not decapitated planarians. Interestingly, as decapitated planarians regenerated their heads, they gradually recovered their sensitivity to cocaine. These results suggested a method to assess planarian brain regeneration and a possible way of identifying compounds that could enhance or hold back brain regeneration. In the present work, we demonstrate that the cholinergic agent cytisine is a suitable reference compound to apply our method. Cytisine induces pSLMs in a concentration-dependent manner in intact (but not decapitated) planarians of the species Girardia tigrina. Based on our data, we developed a behavioral protocol to assess planarian brain regeneration over time. We tested this method to measure the effect of ethanol on G. tigrina's brain regeneration. We found that ethanol slows down the rate of planarian brain regeneration in a concentration-dependent manner, consistently with data from other research groups that tested ethanol effects on planarian brain regeneration using different behavioral protocols. Thus, here we establish a general method using cytisine-induced pSLMs as an indicator of brain regeneration in planarians, a method that shows potential for assessing the effect of pharmacologically active compounds in this process.

Cotinine antagonizes the behavioral effects of nicotine exposure in the planarian Girardia tigrina

Nicotine is one of the most addictive drugs abused by humans. Our laboratory and others have demonstrated that nicotine decreases motility and induces seizure-like behavior in planarians (pSLM, which are vigorous writhing and bending of the body) in a concentration-dependent manner. Nicotine also induces withdrawal-like behaviors in these worms. Cotinine is the major nicotine metabolite in humans, although it is not the final product of nicotine metabolism. Cotinine is mostly inactive in vertebrate nervous systems and is currently being explored as a molecule which possess most of nicotine's beneficial effects and few of its undesirable ones. It is not known whether cotinine is a product of nicotine metabolism in planarians. We found that cotinine by itself does not seem to elicit any behavioral effects in planarians up to a concentration of 1mM. We also show that cotinine antagonizes the aforementioned nicotine-induced motility decrease and also decreases the expression of nicotine-induced pSLMs in a concentration-dependent manner. Also cotinine prevents the manifestation of some of the withdrawal-like behaviors induced by nicotine in our experimental organism. Thus, we obtained evidence supporting that cotinine antagonizes nicotine in this planarian species. Possible explanations include competitive binding of both compounds at overlapping binding sites, at different nicotinic receptor subtypes, or maybe allosteric interactions.

Standardised survey method for identifying catchment risks to water quality

This paper describes the development and application of a systematic methodology to identify and quantify risks in drinking water and recreational catchments. The methodology assesses microbial and chemical contaminants from both diffuse and point sources within a catchment using Escherichia coli, protozoan pathogens and chemicals (including fuel and pesticides) as index contaminants. Hazard source information is gathered by a defined sanitary survey process involving use of a software tool which groups hazards into six types: sewage infrastructure, on-site sewage systems, industrial, stormwater, agriculture and recreational sites. The survey estimates the likelihood of the site affecting catchment water quality, and the potential consequences, enabling the calculation of risk for individual sites. These risks are integrated to calculate a cumulative risk for each sub-catchment and the whole catchment. The cumulative risks process accounts for the proportion of potential input sources surveyed and for transfer of contaminants from upstream to downstream sub-catchments. The output risk matrices show the relative risk sources for each of the index contaminants, highlighting those with the greatest impact on water quality at a sub-catchment and catchment level. Verification of the sanitary survey assessments and prioritisation is achieved by comparison with water quality data and microbial source tracking.

A pilot study of tandem high-dose chemotherapy with stem cell rescue as consolidation for high-risk neuroblastoma: Children's Oncology Group study ANBL00P1

Increasing treatment intensity has improved outcomes for children with neuroblastoma. We performed a pilot study in the Children’s Oncology Group (COG) to assess feasibility and toxicity of a tandem myeloablative regimen without total body irradiation (TBI) supported by autologous CD34 selected peripheral blood stem cells. Forty-one patients with high-risk neuroblastoma were enrolled; eight patients did not receive any myeloablative consolidation procedure, and seven received only one. Two patients out of 41 (4.9%) experienced transplant-related mortality. CD34 selection was discontinued after subjects were enrolled due to serious viral illness. From the time of study enrollment, the overall 3-year event-free survival (EFS) and overall survival (OS) were 44.8±9.6% and 59.2±9.2% (N=41). These results demonstrate that tandem transplantation in the cooperative group setting is feasible and support a randomized comparison of single versus tandem myeloablative consolidation with PBSC support for high-risk neuroblastoma.

Passive transfer of maternal GnRH antibodies does not affect reproductive development in elk (Cervus elaphus nelsoni) calves

Gonadotropin-releasing hormone is intermittently released from the hypothalamus in consistent patterns from before birth to final maturation of the hypothalamic-pituitary-gonadal axis at puberty. Disruption of this signaling via GnRH vaccination during the neonatal period can alter reproduction at maturity. The objective of this study was to investigate the long-term effects of GnRH-antibody exposure on reproductive maturation and function in elk calves passively exposed to high concentrations of GnRH antibodies immediately after birth. Fifteen elk calves (eight males and seven females) born to females treated with GnRH vaccine or sham vaccine during midgestation were divided into two groups based on the concentration of serum GnRH antibodies measured during the neonatal period. Those with robust (>15 pmol (125)I-GnRH bound per mL of serum) titers (N = 10; four females and six males) were designated as the exposed group, whereas those with undetectable titers (N = 5; three females and two males) were the unexposed group. Onset of puberty, reproductive development, and endocrine function in antibody-exposed and unexposed male and female elk calves were compared. Neonatal exposure to high concentrations of GnRH antibodies had no effect on body weight (P = 0.968), endocrine profiles (P > 0.05), or gametogenesis in either sex. Likewise, there were no differences between groups in gross or histologic structure of the hypothalamus, pituitary, testes, or ovaries. Pituitary stimulation with a GnRH analog before the second potential reproductive season induced substantial LH secretion in all experimental elk. All females became pregnant during their second reproductive season and all males exhibited similar mature secondary sexual characteristics. There were no differences between exposure groups in hypothalamic GnRH content (P = 0.979), pituitary gonadotropin content (P > 0.05) or gonadal structure. We concluded that suppressing GnRH signaling through immunoneutralization during the neonatal period likely does not alter long-term reproductive function in this species.

Transcription factor Sp1 regulates SERCA2 gene expression in pressure-overloaded hearts: a study using in vivo direct gene transfer into living myocardium

Pressure-overload hypertrophy results in downregulation of the sarcoplasmic reticulum Ca(2+)-ATPase pump encoding SERCA2 gene that regulates Ca(2+) uptake and myocardial relaxation. We previously characterized a proximal promoter region containing four Sp1 element consensus sequences (-284 to -72 base pairs (bp)) that was responsible for pressure-overload-induced transcriptional regulation. The purpose of the present study was to determine which of the Sp1 sites was responsible for the downregulation of SERCA2 gene transcription under pressure overload. Using an in vivo direct gene transfer assay, SERCA2 gene transcriptional activity was measured under pressure overload. Site-directed mutagenesis of the four Sp1 sites (I-IV) in the SERCA2 gene promoter (-284 to -72 bp) was performed. Wild-type and Sp1 mutant-luciferase reporter constructs were injected into the left-ventricular apices of pressure overload or sham-operated rats, and Sp1 mRNA and SERCA2 gene-luciferase activity was measured sequentially from 3 to 14 d after surgery. At 5 d, Sp1 mRNA in the pressure-overload rats increased to 124 +/- 7% of sham group levels, and pressure-overload-induced SERCA2 transcriptional activity was 15 +/- 4% of sham group when all four Sp1 sites remained intact. Mutation of the Sp1 mutant sites I (-196 to -191 bp) and III (-118 to -113 bp) blocked the inhibitory effect of pressure overload and resulted in SERCA2 gene transcriptional activity of 54 +/- 15% and 56 +/- 7% of sham group, respectively. We conclude that the pressure-overload-induced decrease in SERCA2 mRNA is mediated by Sp1 sites I and III.

Expression of HOX11 in childhood T-lineage acute lymphoblastic leukaemia can occur in the absence of cytogenetic aberration at 10q24: a study from the Children's Cancer Group (CCG)

Clonal genetic aberrations in tumour cells provide critical information for the development of new diagnostic and therapeutic strategies for patients. In paediatric T-cell acute lymphoblastic leukaemia (T-ALL) chromosomal translocations are present in 30-35% of cases. HOX11 and the closely related HOX11L2 genes play a key role in T-ALL. HOX11 is aberrantly activated by either of the two chromosomal translocations, t(7;10) and t(10;14). In this study, HOX11 expression levels were measured by real-time quantitative reverse-transcriptase polymerase chain reaction. We show that leukaemic blasts from 15/76 (19.7%) paediatric T-ALL patients expressed the HOX11 gene at high level and 22/76 (28.9%) at low level, yet the reported frequency for chromosomal rearrangement of 10q24 is 4-7%. Direct cytogenetic analysis revealed that only 2/16 specimens that showed HOX11 expression exhibited abnor-malities at 10q24. These results confirm and extend our previously published findings, and implicate mechanisms other than gross chromosomal translocations for the deregulation of HOX11. Analysis of clinical outcome for the whole study group showed a trend for better outcome for patients with leukaemic blasts expressing HOX11 at high level. A statistically significant difference in clinical outcome was found in a subgroup of 20 patients treated for high-risk disease on CCG-1901 from the Children's Cancer Group, where HOX11 expression in leukaemic blasts conferred a prognostic advantage (P=0.01).

Effects of GnRH agonist (leuprolide) on reproduction and behaviour in female wapiti (Cervus elaphus nelsoni)

Fertility control offers a potential alternative to traditional methods for regulating the growth of overabundant wild ungulate populations. However, current technology is limited due to practical treatment application, undesirable side-effects and economic considerations. A promising non-steroidal, non-immunological approach to contraception involves the use of a potent GnRH agonist. Two experiments were conducted to evaluate the effectiveness of a GnRH agonist (leuprolide) for controlling fertility in captive female wapiti and to assess physiological and behavioural side-effects of the treatment. In Expt 1, the optimum dose of agonist treatment was determined by measuring serum LH response of eight female wapiti to four formulations of leuprolide (0, 45, 90 and 180 mg) administered as a subcutaneous (s.c.) bioimplant. In Expt 2, the effects of leuprolide on wapiti pregnancy rates, duration of suppression of serum LH and progesterone secretion, and short-term behavioural and physiological side-effects were evaluated. All concentrations of leuprolide in Expt 1 were equally effective in reducing serum LH to non-detectable values throughout the 130 day trial. In Expt 2, leuprolide administered before the breeding season was 100% effective at preventing pregnancy in treated females. Serum LH and progesterone were reduced to baseline values by day 92 and remained at this concentration for 195-251 days after treatment, and returned to pretreatment concentrations in the following breeding season. Reproductive behaviour rates were similar for treated and untreated wapiti for all behaviour categories for both the breeding and post-breeding seasons. Haematology and blood chemistry parameters of treated and un-treated females were similar, and seasonal intake and body weight dynamics appeared normal. In conclusion, leuprolide is a safe, effective contraceptive agent and can potentially suppress fertility in female wapiti for one breeding season.

Short-chain phosphatidates are subtype-selective antagonists of lysophosphatidic acid receptors

Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are members of the phospholipid growth factor family. A major limitation in the field to date has been a lack of receptor subtype-specific agonists and antagonists. Here, we report that dioctylglycerol pyrophosphate and dioctylphosphatidic acid are selective antagonists of the LPA(1) and LPA(3) receptors, but prefer LPA(3) by an order of magnitude. Neither molecule had an agonistic or antagonistic effect on LPA(2) receptor. Consistent with this receptor subtype selectivity, dioctylglycerol pyrophosphate inhibited cellular responses to LPA in NIH3T3 fibroblasts, HEY ovarian cancer cells, PC12 pheochromocytoma cells, and Xenopus laevis oocytes. Responses elicited by S1P in these cell lines that endogenously express S1P(1), S1P(2), S1P(3), and S1P(5) receptors were unaffected by dioctylglycerol pyrophosphate. Responses evoked by the G protein-coupled receptor ligands acetylcholine, serotonin, ATP, and thrombin receptor-activating peptide were similarly unaffected, suggesting that the short-chain phosphatidates are receptor subtype-specific lysophosphatidate antagonists.

Specific proteolysis of the NR2 subunit at multiple sites by calpain

The NMDA subtype of glutamate receptor plays an important role in the molecular mechanisms of learning, memory and excitotoxicity. NMDA receptors are highly permeable to calcium, which can lead to the activation of the calcium-dependent protease, calpain. In the present study, the ability of calpain to modulate NMDA receptor function through direct proteolytic digestion of the individual NMDA receptor subunits was examined. HEK293t cells were cotransfected with the NR1a/2A, NR1a/2B or NR1a/2C receptor combinations. Cellular homogenates of these receptor combinations were prepared and digested by purified calpain I in vitro. All three NR2 subunits could be proteolyzed by calpain I while no actin or NR1a cleavage was observed. Based on immunoblot analysis, calpain cleavage of NR2A, NR2B and NR2C subunits was limited to their C-terminal region. In vitro calpain digestion of fusion protein constructs containing the C-terminal region of NR2A yielded two cleavage sites at amino acids 1279 and 1330. Although it has been suggested that calpain cleavage of the NMDA receptor may act as a negative feedback mechanism, the current findings demonstrated that calpain cleavage did not alter [(125)I]MK801 binding and that receptors truncated to the identified cleavage sites had peak intracellular calcium levels, (45)Ca uptake rates and basal electrophysiological properties similar to wild type.

High-dose melphalan, etoposide, total-body irradiation, and autologous stem-cell reconstitution as consolidation therapy for high-risk Ewing's sarcoma does not improve prognosis

PURPOSE

To determine whether consolidation therapy with high-dose melphalan, etoposide, and total-body irradiation (TBI) with autologous stem-cell support would improve the prognosis for patients with newly diagnosed metastatic Ewing's sarcoma (ES).

PATIENTS AND METHODS

Thirty-two eligible patients with newly diagnosed ES metastatic to bone and/or bone marrow were enrolled onto this study. Treatment was initially comprised of five cycles of induction chemotherapy (cyclophosphamide, doxorubicin, and vincristine alternating with ifosfamide and etoposide) and local control. Peripheral-blood stem-cell collection was performed after the second cycle of chemotherapy, with delay if the bone marrow was persistently involved. If patients had a good response to initial therapy, they proceeded to consolidation therapy with melphalan, etoposide, TBI, and stem-cell support.

RESULTS

Of the 32 eligible patients, 23 proceeded to high-dose therapy consolidation. Of the nine patients who did not proceed to consolidation, four were secondary to progressive disease and two were secondary to toxicity. Three patients died from toxicity during the high-dose phase of the therapy. The majority of the patients who underwent high-dose consolidation therapy experienced relapse and died with progressive disease. Two-year event-free survival (EFS) for all eligible patients is 20%. The 2-year post-stem-cell reconstitution EFS for the subset of 23 patients who received consolidation therapy is 24%. Analysis of peripheral-blood stem-cell collections by molecular techniques for minimal residual disease showed contamination of at least some samples by tumor cells in all three patients with available data.

CONCLUSION

Consolidation with high-dose melphalan, etoposide, TBI, and autologous stem-cell support failed to improve the probability of EFS in this cohort of patients with newly diagnosed metastatic ES.

Erosion of root epidermal cell walls by Rhizobium polysaccharide-degrading enzymes as related to primary host infection in the Rhizobium-legume symbiosis

A central event of the infection process in the Rhizobium-legume symbiosis is the modification of the host cell wall barrier to form a portal of entry large enough for bacterial penetration. Transmission electron microscopy (TEM) indicates that rhizobia enter the legume root hair through a completely eroded hole that is slightly larger than the bacterial cell and is presumably created by localized enzymatic hydrolysis of the host cell wall. In this study, we have used microscopy and enzymology to further clarify how rhizobia modify root epidermal cell walls to shed new light on the mechanism of primary host infection in the Rhizobium-legume symbiosis. Quantitative scanning electron microscopy indicated that the incidence of highly localized, partially eroded pits on legume root epidermal walls that follow the contour of the rhizobial cell was higher in host than in nonhost legume combinations, was inhibited by high nitrate supply, and was not induced by immobilized wild-type chitolipooligosaccharide Nod factors reversibly adsorbed to latex beads. TEM examination of these partially eroded, epidermal pits indicated that the amorphous, noncrystalline portions of the wall were disrupted, whereas the crystalline portions remained ultrastructurally intact. Further studies using phase-contrast and polarized light microscopy indicated that (i) the structural integrity of clover root hair walls is dependent on wall polymers that are valid substrates for cell-bound polysaccharide-degrading enzymes from rhizobia, (ii) the major site where these rhizobial enzymes can completely erode the root hair wall is highly localized at the isotropic, noncrystalline apex of the root hair tip, and (iii) the degradability of clover root hair walls by rhizobial polysaccharide-degrading enzymes is enhanced by modifications induced during growth in the presence of chitolipooligosaccharide Nod factors from wild-type clover rhizobia. The results suggest a complementary role of rhizobial cell-bound glycanases and chitolipooligosaccharides in creating the localized portals of entry for successful primary host infection.

Direct Quantitative Analysis of Lysophosphatidic Acid Molecular Species by Stable Isotope Dilution Electrospray Ionization Liquid Chromatography–Mass Spectrometry

In order to better understand the role of lysophosphatidic acid (LPA) in physiology and pathophysiology, it is necessary to accurately determine the molecular species and amounts of LPA in biological samples. We have developed a stable-isotope dilution, liquid chromatography-mass spectrometry assay for the direct quantitative analysis of 1-acyl-LPA. This method utilizes a deuterium-labeled internal standard, LPA (18:0-d(35)), and a single liquid-liquid extraction with acidic butanol that allows >95% recovery of LPA, followed by online normal-phase liquid chromatography-mass spectrometry. This protocol allows for the accurate, sensitive, and reproducible analysis of the individual 1-acyl-LPA species present in biological samples. The utility of the assay is demonstrated through the analysis of LPA species in plasma and serum from human volunteers. Total LPA in EDTA plasma was 0.61 +/- 0.14 microM in males and 0.74 +/- 0.17 microM in females, which increased to 0.91 +/- 0.23 and 0.99 +/- 0.38 microM after incubation for 24 h at 25 degrees C. Total LPA in serum was 0.85 +/- 0.22 microM in males and 1.57 +/- 0.56 microM in females, which increased to 4.78 +/- 0.89 and 5.57 +/- 0.73 microM after incubation for 24 h at 25 degrees C.

Sphingosylphosphocholine is a naturally occurring lipid mediator in blood plasma: a possible role in regulating cardiac function via sphingolipid receptors

Blood plasma and serum contain factors that activate inwardly rectifying GIRK1/GIRK4 K+ channels in atrial myocytes via one or more non-atropine-sensitive receptors coupled to pertussis-toxin-sensitive G-proteins. This channel is also the target of muscarinic M(2) receptors activated by the physiological release of acetylcholine from parasympathetic nerve endings. By using a combination of HPLC and TLC techniques with matrix-assisted laser desorption ionization-time-of-flight MS, we purified and identified sphingosine 1-phosphate (SPP) and sphingosylphosphocholine (SPC) as the plasma and serum factors responsible for activating the inwardly rectifying K+ channel (I(K)). With the use of MS the concentration of SPC was estimated at 50 nM in plasma and 130 nM in serum; those concentrations exceeded the 1.5 nM EC(50) measured in guinea-pig atrial myocytes. With the use of reverse-transcriptase-mediated PCR and/or Western blot analysis, we detected Edg1, Edg3, Edg5 and Edg8 as well as OGR1 sphingolipid receptor transcripts and/or proteins. In perfused guinea-pig hearts, SPC exerted a negative chronotropic effect with a threshold concentration of 1 microM. SPC was completely removed after perfusion through the coronary circulation at a concentration of 10 microM. On the basis of their constitutive presence in plasma, the expression of specific receptors, and a mechanism of ligand inactivation, we propose that SPP and SPC might have a physiologically relevant role in the regulation of the heart.

Hemizygous p16(INK4A) deletion in pediatric acute lymphoblastic leukemia predicts independent risk of relapse

The genes at the INK4A/ARF locus at 9p21 are frequently involved in human cancer. Virtually all p16(INK4A) exon 2 (henceforth called p16) inactivation in pediatric acute lymphoblastic leukemia (ALL) occurs by gene deletion. The results of this study illustrate that real-time quantitative polymerase chain reaction is capable of detecting gene deletion in primary patient specimens with a precision not previously achieved by conventional methods. Importantly, this assay includes the detection of hemizygous deletions. The study revealed, strikingly, that the risk ratio for relapse for hemizygous deletion compared with no deletion was 6.558 (P =.00687) and for homozygous deletion was 11.558 (P =.000539). These results confirm and extend the authors' previous findings that homozygous deletion of p16 in pediatric ALL patients is an independent prognostic indicator of outcome from therapy.

Identification of Edg1 receptor residues that recognize sphingosine 1-phosphate

Originating from its DNA sequence, a computational model of the Edg1 receptor has been developed that predicts critical interactions with its ligand, sphingosine 1-phosphate. The basic amino acids Arg(120) and Arg(292) ion pair with the phosphate, whereas the acidic Glu(121) residue ion pairs with the ammonium moiety of sphingosine 1-phosphate. The requirement of these interactions for specific ligand recognition has been confirmed through examination of site-directed mutants by radioligand binding, ligand-induced [(35)S]GTPgammaS binding, and receptor internalization assays. These ion-pairing interactions explain the ligand specificity of the Edg1 receptor and provide insight into ligand specificity differences within the Edg receptor family. This computational map of the ligand binding pocket provides information necessary for understanding the molecular pharmacology of this receptor, thus underlining the potential of the computational method in predicting ligand-receptor interactions.

Psychosis and nonadherence in an HIV-seropositive patient

While adherence to antiretroviral therapy is of paramount importance in the treatment of HIV-infected patients, optimal adherence can be challenging to achieve. Furthermore, the presence of comorbid psychiatric illness can potentially compromise treatment adherence. This Case Report highlights the difficulties encountered in the care and treatment adherence of an HIV-seropositive patient who presented with psychotic symptoms. Treatment, ethical, and legal issues are discussed.

Frequency-dependent changes in calcium cycling and contractile activation in SERCA2a transgenic mice

OBJECTIVE

This study was undertaken to investigate the mechanism of altered contractility in hearts from transgenic mice overexpressing the sarcoplasmic reticulum (SR) Ca2+ ATPase (SERCA2a). In particular, we sought to determine whether the reported increase in contractility is frequency-dependent, as might be expected if attributable to changes in SR Ca2+ loading.

METHODS

Intracellular [Ca2+] and contractile force were measured at room temperature (22 degrees C) simultaneously in fura-2-loaded isometrically-contracting trabeculae dissected from the hearts of FVB/N control (n = 6) or SERCA2a transgenic (n = 6) mice.

RESULTS

SERCA transgenics exhibit a positive force-frequency relationship, but this was flat in age- and strain-matched controls. SERCA transgenics exhibit a sizable increase in calcium transient amplitude relative to controls, with a concomitant increase in force generation at higher frequencies of stimulation. Amplitudes of Ca2+ transients (transgenics: 1.56 +/- 0.09 micromol/L, controls: 1.21 +/- 0.14) and twitches (transgenics: 21.71 +/- 0.91 mN/mm2, controls: 13.74 +/- 1.67) were significantly different at 2.0 Hz stimulation (P < 0.05).

CONCLUSION

An increase in SERCA expression increases the ability of the sarcoplasmic reticulum to store calcium, such that more calcium is available to be released during each heartbeat at higher stimulation rates.

The total care unit for pediatric hematology and oncology, Princess Margaret Hospital for Children, Perth, Australia

The total care unit for the treatment of pediatric hematology/oncology in Perth, Australia is so named to embody the philosophy of multidisciplinary care of children and their families. Where possible, patients are treated according to randomized controlled trials of the large cooperative Children's Cancer Group. There is a seamless association of clinical and laboratory research. Hemopoietic stem cell transplantation is managed within the unit, as well as treatment of a range of non-malignant hematological disorders. Long-term follow-up of survivors of childhood cancer is coordinated from the unit.

Reactions of beta-carotene with cigarette smoke oxidants. Identification of carotenoid oxidation products and evaluation of the prooxidant/antioxidant effect

Recent intervention trials reported that smokers given dietary beta-carotene supplementation exhibited an increased risk of lung cancer and overall mortality. beta-Carotene has been hypothesized to promote lung carcinogenesis by acting as a prooxidant in the smoke-exposed lung. We have examined the interactions of cigarette smoke with beta-carotene in model systems. Both whole smoke and gas-phase smoke oxidized beta-carotene in toluene to several products, including carbonyl-containing polyene chain cleavage products and beta-carotene epoxides. A major product of the reaction was identified as 4-nitro-beta-carotene, which was formed by nitrogen oxides in smoke. Both cis and all-trans isomers of 4-nitro-beta-carotene were detected. The hypothesis that smoke-driven beta-carotene autoxidation exerts prooxidant effects was tested in a liposome system. Lipid peroxidation in dilinoleoylphosphatidylcholine liposomes exposed to gas-phase smoke was modestly inhibited by the incorporation of 0.1 mol % beta-carotene. Both the lipid soluble antioxidant alpha-tocopherol and the water soluble antioxidant ascorbate were oxidized more slowly by gas-phase smoke exposure in liposomes containing beta-carotene. These data indicate that beta-carotene exerts weak antioxidant effects against smoke-induced oxidative damage in vitro. It is unlikely that a prooxidant effect of beta-carotene occurs under biologically relevant conditions or is responsible for an increased incidence of lung cancer observed in smokers who consume beta-carotene supplements.

The sarcoplasmic reticulum Ca2+-ATPase (SERCA2) gene promoter activity is decreased in response to severe left ventricular pressure-overload hypertrophy in rat hearts

The sarcoplasmic reticulum Ca2+-ATPase (SERCA2) pump plays a key role in the contraction-relaxation cycle of the myocardium by controlling the intracellular Ca2+ concentration. SERCA2 protein and mRNA expression levels, as well as, SR Ca2+ uptake function are depressed in hypertrophied and failing myocardium. At this time, the molecular mechanisms regulating SERCA2 gene transcription during hypertrophy and heart failure are not completely understood, especially in vivo. Direct gene transfer into adult cardiac tissue has recently been shown to be a useful technique to study in vivo gene regulation. In this study, SERCA2 promoter-luciferase (Luc) reporter constructs of various lengths were injected into the beating left ventricular apex of adult rats (groups = compensated hypertrophy, heart failure, and controls) and the expression level was analysed. Our SERCA2 promoter analyses revealed three positive regulatory regions between -1810 bp and -1110 bp, -658 bp and -284 bp, and -267 bp and -72 bp and a negative regulatory region between -1110 bp and -658 bp, important for in vivo expression in rat hearts. SERCA2 promoter activity was also assessed in rat hearts with compensated pressure-overload hypertrophy (induced by the DOCA-salt treatment) and heart failure (induced by severe ascending aortic constriction). In the DOCA-salt-induced hypertrophy model, SERCA2 promoter activity was similar to that of sham controls. In contrast, severe constriction of the ascending aorta decreased the expression of the -1810 Luc and -1110 Luc constructs by 92.8% and 64.3%, respectively. This study suggests that only severe pressure-overload hypertrophy produces a significant decrease in SERCA2 promoter activity, and the promoter region extending to -1810 bp is sufficient for the down regulation of SERCA2 gene expression.

Targeted overexpression of the sarcoplasmic reticulum Ca2+-ATPase increases cardiac contractility in transgenic mouse hearts

Cardiac hypertrophy and heart failure are known to be associated with a reduction in Ca2+-ATPase pump levels of the sarcoplasmic reticulum (SR). To determine whether, and to what extent, alterations in Ca2+ pump numbers can affect contraction and relaxation parameters of the heart, we have overexpressed the cardiac SR Ca2+-ATPase specifically in the mouse heart using the alpha-myosin heavy chain promoter. Analysis of 2 independent transgenic lines demonstrated that sarco(endo)plasmic reticulum Ca2+-ATPase isoform (SERCA2a) mRNA levels were increased 3.88+/-0. 4-fold and 7.90+/-0.2-fold over those of the control mice. SERCA2a protein levels were increased by 1.31+/-0.05-fold and 1.54+/-0. 05-fold in these lines despite high levels of mRNA, suggesting that complex regulatory mechanisms may determine the SERCA2a pump levels. The maximum velocity of Ca2+ uptake (Vmax) was increased by 37%, demonstrating that increased pump levels result in increased SR Ca2+ uptake function. However, the apparent affinity of the SR Ca2+-ATPase for Ca2+ remains unchanged in transgenic hearts. To evaluate the effects of overexpression of the SR Ca2+ pump on cardiac contractility, we used the isolated perfused work-performing heart model. The transgenic hearts showed significantly higher myocardial contractile function, as indicated by increased maximal rates of pressure development for contraction (+dP/dt) and relaxation (-dP/dt), together with shortening of the normalized time to peak pressure and time to half relaxation. Measurements of intracellular free calcium concentration and contractile force in trabeculae revealed a doubling of Ca2+ transient amplitude, with a concomitant boost in contractility. The present study demonstrates that increases in SERCA2a pump levels can directly enhance contractile function of the heart by increasing SR Ca2+ transport.

Enhanced myocardial contractility and increased Ca2+ transport function in transgenic hearts expressing the fast-twitch skeletal muscle sarcoplasmic reticulum Ca2+-ATPase

In this study, we investigated whether the fast-twitch skeletal muscle sarco(endo)plasmic reticulum Ca2+ transport pump (SERCA1a) can functionally substitute the cardiac SERCA2a isoform and how its overexpression affects cardiac contractility. For this purpose, we generated transgenic (TG) mice that specifically overexpress SERCA1a in the heart, using the cardiac-specific alpha-myosin heavy chain promoter. Ectopic expression of SERCA1a resulted in a 2.5-fold increase in the amount of total SERCA protein. At the same time, the level of the endogenous SERCA2a protein was decreased by 50%, whereas the level of other muscle proteins, including calsequestrin, phospholamban, actin, and tropomyosin, remained unchanged. The steady-state level of SERCA phosphoenzyme intermediate was increased 2.5-fold, and the maximal velocity of Ca2+ uptake was increased 1.7-fold in TG hearts, demonstrating that the overexpressed protein is functional. Although the basal cytosolic calcium signal was decreased by 38% in TG cardiomyocytes, the amplitude of cytosolic calcium signal was increased by 71.8%. The rate of calcium resequestration was also increased in TG myocytes, which was reflected by a 51.6% decrease in the normalized time to 80% decay of calcium signal. This resulted in considerably increased peak rates of myocyte shortening and relengthening (50.0% and 66.6%, respectively). Cardiac functional analysis using isolated work-performing heart preparations revealed significantly faster rates of contraction and relaxation in TG hearts (41.9% and 39.5%, respectively). The time to peak pressure and the time to half-relaxation were shorter (29.1% and 32.7%, respectively). In conclusion, our study demonstrates that the SERCA1a pump can functionally substitute endogenous SERCA2a, and its overexpression significantly enhances Ca2+ transport and contractile function of the myocardium. These results also demonstrate that the SERCA pump level is a critical determinant of cardiac contractility.

Gene amplification and transcriptional upregulation of the sarco/endoplasmic reticulum Ca2+ transport ATPase in thapsigargin-resistant hamster smooth muscle cells

We have selected a series of cell lines from the parental Syrian hamster smooth muscle cell line DDT1-MF2that are resistant to thapsigargin (TG), a specific inhibitor of the sarcoplasmic/endoplasmic reticulum Ca2+transport ATPases (SERCAs). Cells were selected for resistance to TG in the presence or absence of cyclosporin (CSA), which is a competitive inhibitor of the multidrug transporter p-glycoprotein (pgp). Since TG is a known substrate for pgp, selection for TG resistance was carried out in the presence of CSA in an attempt to minimize the contribution of pgp, and to identify the potential range of adaptive responses of the SERCA pump itself, during the development of the TG-resistant phenotype. Irrespective of whether the selection is carried out in the presence or absence of CSA, pgp is overexpressed in the TG-resistant DDT1-MF2cells. SERCA protein is also overproduced in the TG-resistant cell lines, which occurs through one of several mechanisms. Included among these, is amplification of the SERCA gene and enhanced transcription of the gene. Enhanced transcription is observed only upon long-term selection and occurs through the SERCA gene proximal promoter elements. Although SERCA transcription in wild-type cells is dependent upon the -284 to -72 bp region of the SERCA promoter, the TG-resistant cells utilize both the -284 to -72 bp and the -72 to +80 bp promoter regions for enhanced SERCA transcription. That is, additional elements within the -72 to +80 bp region are recruited in the TG-resistant cells to allow for increased SERCA expression. A post-transcriptional step may also be recruited by the TG-resistant cells in their overall strategy to produce increased amounts of the SERCA protein. These studies demonstrate that the DDT1-MF2cells can utilize different mechanisms which lead to increased levels of SERCA protein as the cells adapt to inhibition of the ATPase by TG.

Sarco(endo)plasmic reticulum Ca2+ ATPase isoforms and their role in muscle physiology and pathology

Recent studies suggest that SR Ca2+ transport function is altered in hypertrophied and failing myocardium. To understand whether alterations in SR Ca2+ ATPase levels affect myocardial contractility, we generated transgenic mice that specifically overexpress SERCA2a or SERCA1 pump in the mouse heart, using the cardiac alpha-MHC promoter. Analysis of SERCA2a transgenic mice show both an increase in mRNA and protein levels (120-150% of the wild type). Isolated work performing heart preparations revealed that SERCA2a mice have improved myocardial performance. On the other hand, SERCA1 overexpression in the heart resulted in isoform replacement without any change in total SERCA protein. Interestingly, SERCA1 transgenic hearts exhibited super contractility with a significant increase in rates of muscle contraction (+dp/dt) and relaxation (-dp/dT). The time to peak pressure and half-time to relaxation were significantly shorter.

Pharmacodynamics of recombinant human DNase I in serum

Recombinant human deoxyribonuclease I (rhDNase) may be an effective therapeutic for the treatment of systemic lupus erythematosus (SLE). The pharmacodynamics of rhDNase in serum was investigated using two activity assays: one based on hydrolysis of a radiolabelled phage DNA and the other based on hydrolysis of human chromatin. The concentration of endogenous immunoreactive DNase in sera from 16 normal subjects was 3.2 +/- 1.4 ng/ml (mean +/- s.d.); however, low levels or no nuclease activity were detected in the same sera, suggesting the presence of DNase inhibitors. We assessed the ability of rhDNase to degrade DNA in undiluted serum, since the observed inhibition of endogenous DNase was reversed upon dilution. Addition of rhDNase to undiluted serum at a concentration of 50-100 ng/ml was necessary for degradation of radiolabelled phage DNA. The activity of rhDNase added to serum from normal subjects and SLE patients was similar. rhDNase degraded human chromatin and chromatin/anti-DNA immune complexes in serum with similar potency (EC50 approximately 100-200 ng/ml). A 500-fold variation in the chromatin/anti-DNA stoichiometry did not significantly affect the digestion of these immune complexes by rhDNase in buffer. These results indicate that a minimum rhDNase concentration of 50-100 ng/ml in serum was required to achieve detectable catalytic activity and that the presence of antibodies to DNA did not inhibit the degradation of DNA/anti-DNA immune complexes.

Improved potency of hyperactive and actin-resistant human DNase I variants for treatment of cystic fibrosis and systemic lupus erythematosus

The ability of recombinant human DNase I (DNase I) to degrade DNA to lower molecular weight fragments is the basis for its therapeutic use in cystic fibrosis (CF) patients and its potential use as a treatment for systemic lupus erythematosus (SLE). To increase the potency of human DNase I, we have generated and characterized three classes of mutants: (a) hyperactive variants, which have from one to six additional positively charged residues (+1 to +6) and digest DNA much more efficiently relative to wild type, (b) actin-resistant variants, which are no longer inhibited by G-actin, a potent inhibitor of DNase I, and (c) combination variants that are both hyperactive and actin-resistant. For DNA scission in CF sputum where the DNA concentration and length are large, we measured a approximately 20-fold increase in potency relative to wild type for the +3 hyperactive variant Q9R/E13R/N74K or the actin-resistant variant A114F; the hyperactive and actin-resistant combination variant was approximately 100-fold more potent than wild type DNase I. For digesting lower concentrations of DNA complexed to anti-DNA antibodies in human serum, we found a maximal enhancement of approximately 400-fold over wild type for the +2 variant E13R/N74K. The +3 enzymes have approximately 4000-fold enhancement for degrading moderate levels of exogenous DNA spiked into human serum, whereas the +6 enzyme has approximately 30,000-fold increased activity for digesting the extremely low levels of endogenous DNA found in serum. The actin resistance property of the combination mutants further enhances the degree of potency in human serum. Thus, the human DNase I variants we have engineered for improved biochemical and pharmacodynamic properties have greater therapeutic potential for treatment of both CF and SLE.

Surgical implantation and evaluation of heart rate transmitters in captive bighorn sheep

A surgical approach was developed for implantation of transmitters to monitor heart rate of bighorn sheep (Ovis canadensis) with an objective of discrete long-term, long-range data collection. We surgically implanted Telonics model HR400 transmitters on the dorsolateral thorax of 15 captive adult bighorn sheep ewes in April-May and October-November 1995. No complications or marked impairment of function were associated with the surgery; however, a transmitter was passively expelled from one ewe 19.5 mo post-implantation. Twelve of 15 transmitters remained functional > or = 1 yr, while three failed 3.5 to 4.5 mo following implantation. Heart rate data collected from the transmitters using a Lotek SRX_400 telemetry receiver/datalogger equipped with W9 EVENT_LOG accurately reflected heart rate as measured with electrocardiogram tracings. Line of sight signal range was at least 800 m in 95% (37/39) of collections made from standing ewes, while data could be collected reliably (74%; 29/39) to 600 m from bedded ewes. When a reliable long-lasting inconspicuous telemetry system is required, we believe that this approach holds promise for success in free-ranging as well as captive ungulates.

A diet supplement for captive wild ruminants

Nutritional husbandry of captive wild ruminants often requires feeding these animals a supplemental diet to enhance their health, reproductive performance, and productivity. Although supplemental diets for wild ruminants are commercially available, few have been evaluated in controlled intake and digestion trials. Voluntary intake, digestive efficiency, nitrogen retention, and gross energy utilization of pronghorn (Antilocapra americana), mule deer (Odocoileus hemionus), mountain sheep (Ovis canadensis), mountain goats (Oreamnos americanus), and wapiti (Cervus elaphus) consuming a high-energy, high-protein pelleted supplement were compared. Voluntary intake of dry matter, energy, and nitrogen were similar (P > 0.34) between mountain goats and mountain sheep and consistently lower (P < 0.03) for these species than for pronghorn, mule deer, and wapiti. Differences in digestive efficiency among species were inversely related to dry matter intake rates. Apparent digestibility of dry matter, organic matter, and neutral-detergent fiber was 10-20% higher for mountain goats and mountain sheep than for the other species (P < 0.04). Although these findings suggest a superior digestive efficiency for mountain goats and mountain sheep, species comparisons are inconclusive because of the confounding effects of season and ambient temperature on voluntary intake and digestion. Under the conditions of this experiment, the diet tested was safe, nutritious, and highly palatable. Protein and energy concentrations appear to be sufficient to meet or exceed known nutritional requirements of captive wild ruminants.

A novel E box/AT-rich element is required for muscle-specific expression of the sarcoplasmic reticulum Ca2+-ATPase (SERCA2) gene

The cardiac/slow twitch sarcoplasmic reticulum (SR) Ca2+-ATPase gene (SERCA2 ) encodes a calcium transport pump whose expression is regulated in a tissue- and development-specific manner. Previously we have identified two distinct positive regulatory regions (bp -284 to -72 and -1815 to -1105) as important for SERCA2 promoter activity. Here we demonstrate that the SERCA2 distal promoter region functions like an enhancer by activating a heterologous promoter (TK) in a muscle cell-specific manner. Through deletion analysis a core enhancer region was delimited to the -1467 to -1105 bp fragment. We identified the E box/AT-rich element located at -1115 bp as critical for maximal enhancer activity. Gel mobility shift studies revealed that this E box/AT-rich element specifically binds a protein which is induced during Sol8 myogenesis. This region includes two other cis -acting elements, CArG and MCAT, which also bind specific nuclear protein complexes from Sol8 myotubes. Mutagenesis of each of these sites resulted in decreased SERCA/TK-CAT promoter activity. Based on these data, we propose that the E box/AT-rich element may contribute along with CArG and MCAT elements to the overall activation and regulation of the SERCA2 gene promoter.

A new pineoblastoma cell line, PER-480, with der(10)t(10;17), der(16)t(1;16), and enhanced MYC expression in the absence of gene amplification

Pineoblastoma is a rare, but highly malignant tumor of the central nervous system (CNS) in children and is classified as a central primitive neuroectodermal tumor (PNET). Despite notable recent advances in understanding the molecular genetic basis of malignancies, the pathogenesis of PNETs remains enigmatic. There is scant information on the cytogenetics of PNETs arising in the pineal gland and the only three reported cases did not show any common aberrations. Here we report the establishment and characterization of a new pineoblastoma cell line, PER-480. The biopsy material and the cell line were characterized using light and electron microscopy and immunohistochemical analyses. The cell line was examined for expression of cell surface markers using a panel of monoclonal antibodies and by cytogenetic analysis. MYC family genes were studied at the DNA, RNA, and protein level. Cell line PER-480 showed neuronal differentiation and the karyotype demonstrated two abnormalities, a der(10)t(10;17) and a der(16)t(1;16). An intriguing finding is that all three pineoblastoma cell lines established in our laboratory, PER-452, PER-453, and PER-480, showed enhanced expression but not amplification of a member of the MYC family of proto-oncogenes. Cell line PER-480 reported here will be useful for the further investigation of the molecular genetic basis of central PNETs.

Homozygous deletion of the p16/MTS1 gene in pediatric acute lymphoblastic leukemia is associated with unfavorable clinical outcome

The p16 gene (MTS1, CDKN2, p16INK4A, CDKI) encoding an inhibitor of cyclin-dependent kinase 4 (cdk4) has been found to be deleted in various types of tumors, including leukemia, and is thought to code for a tumor suppressor gene. Our preliminary findings on eight pediatric patients with acute lymphoblastic leukemia (ALL) suggested that the survival of patients carrying a homozygous p16 gene deletion was significantly inferior to that of those without a deletion. The present study on 48 patients tested the hypothesis that the clinical outcome for pediatric ALL patients is correlated with the presence or absence of the p16 gene. Overall, nine of 48 children (18.3%) carried a homozygous p16 deletion. Such deletions were significantly more common (P = .003) among T-ALL patients (five of eight, 62.5%) than among precursor-B-ALL patients (four of 40, 10.0%). Of nine patients exhibiting p16 deletions, eight (88.9%) were classified as high-risk patients by the recognized prognostic factors of age, white blood cell count, and T-cell phenotype. The 4-year event-free survival in the study population as a whole was 72.7%. Without adjustment for other risk factors (univariate model), the presence of a homozygous p16 deletion was associated with a markedly increased probability of both relapse (P = .0003) and death (P = .002). These findings raise the question of whether the p16 deletion itself confers an increased risk of relapse after adjusting for the known risk factors. In this analysis, the estimated risk multiplier factor for relapse in patients carrying the p16 deletion was 14.0 (P = .0004) and for the risk of death 15.6 (P = .0008). We therefore conclude that the presence of a homozygous p16 deletion may well be an important risk factor for both relapse and death in childhood ALL, and that its prognostic effect is not a consequence of confounding by other factors already known to influence outcome in this disease.

The prevalence of hepatitis C in survivors of paediatric malignancy

OBJECTIVE

To assess the prevalence of hepatitis C in 200 patients with paediatric malignancies, surviving in remission more than 5 years from diagnosis, who had received blood product transfusions before 1990 when routine screening of blood products for hepatitis C began.

METHOD

The second and third generation Abbott Diagnostics ELISA was used to assess hepatitis C seropositivity. Seropositive patients and those with abnormal liver transaminases were assessed by hepatitis C virus RNA polymerase chain reaction (PCR).

RESULTS

A low incidence (4%) of seropositivity for hepatitis C was found in survivors of paediatric malignancy who were transfused prior to routine screening of blood products in this cohort.

CONCLUSIONS

All patients identified have evidence of hepatitis and may be at high risk of developing cirrhosis.

Engineering actin-resistant human DNase I for treatment of cystic fibrosis

Human deoxyribonuclease I (DNase I), an enzyme recently approved for treatment of cystic fibrosis (CF), has been engineered to create two classes of mutants: actin-resistant variants, which still catalyze DNA hydrolysis but are no longer inhibited by globular actin (G-actin) and active site variants, which no longer catalyze DNA hydrolysis but still bind G-actin. Actin-resistant variants with the least affinity for actin, as measured by an actin binding ELISA and actin inhibition of [33P] DNA hydrolysis, resulted from the introduction of charged, aliphatic, or aromatic residues at Ala-114 or charged residues on the central hydrophobic actin binding interface at Tyr-65 or Val-67. In CF sputum, the actin-resistant variants D53R, Y65A, Y65R, or V67K were 10-to 50-fold more potent than wild type in reducing viscoelasticity as determined in sputum compaction assays. The reduced viscoelasticity correlated with reduced DNA length as measured by pulsed-field gel electrophoresis. In contrast, the active site variants H252A or H134A had no effect on altering either viscoelasticity or DNA length in CF sputum. The data from both the active site and actin-resistant variants demonstrate that the reduction of viscoelasticity by DNase I results from DNA hydrolysis and not from depolymerization of filamentous actin (F-actin). The increased potency of the actin-resistant variants indicates that G-actin is a significant inhibitor of DNase I in CF sputum. These results further suggest that actin-resistant DNase I variants may have improved efficacy in CF patients.

Multiple Sp1 binding sites in the cardiac/slow twitch muscle sarcoplasmic reticulum Ca2+-ATPase gene promoter are required for expression in Sol8 muscle cells

The rabbit cardiac/slow twitch muscle sarcoplasmic reticulum Ca2+-ATPase (SERCA2) gene encodes a Ca2+ transport pump whose expression is regulated during skeletal and cardiac muscle development and in response to various pathophysiological and hormonal states. Employing transient transfection analyses in Sol8 muscle cells, we have identified two positive regulatory regions, one distal (-1810 base pair (bp) to -1110 bp) and one proximal (-284 bp to -72 bp), within the SERCA2 promoter. The proximal promoter region from -284 bp to -80 bp was shown to confer muscle-specific expression to a heterologous promoter in Sol8 cells. This region is highly GC-rich containing the consensus sequence for four Sp1 elements (GGGCGG) and three Sp1-like elements (GGGAGG). DNase I footprint analysis with Sol8 nuclear extracts and purified Sp1 protein showed the protection of the seven Sp1 binding sites. In addition, site-directed mutagenesis of the Sp1 consensus sites demonstrated that Sp1 sites are essential for the muscle-specific expression of the SERCA2 promoter. Furthermore, we demonstrate that cotransfection of an Sp1 expression vector together with SERCA2-CAT constructs can up-regulate SERCA2 promoter activity. These results imply that the Sp1 transcription factor plays an important role in the transcriptional regulation of SERCA2 within muscle cells.

Gonadotropin-releasing hormone analog-induced patterns of luteinizing hormone secretion in female Wapiti (Cervus elaphus nelsoni) during the breeding season, anestrus, and pregnancy

We conducted two studies to determine the pattern of GnRH analog-induced LH secretion in adult female wapiti during the breeding season, anestrus, and pregnancy. In the first study, we measured LH secretion during the breeding season and anestrus in five females challenged with each of five doses of GnRH analog (0.3, 1, 3, 10, and 30 micrograms/50 kg BW). In the second study, LH response was determined in six pregnant females treated with six doses of GnRH analog (0.5, 1, 2, 4, 8, and 16 micrograms/50 kg BW). Animals were fitted nonsurgically with indwelling jugular catheters, and blood samples were collected at 0, 30, 60, 90, 120, 180, 240, 300, 360, 420, and 480 min postinjection. Mean maximum serum concentrations of LH were not different (p = 0.45) between females treated during the breeding season (mean = 29.1 +/- 1.9 [SE] ng/ml) and anestrus (mean = 32.4 +/- 4.3 [SE] ng/ml); however, anestrous females required 3.3 times more GnRH analog (3 vs. 10 micrograms/50 kg BW) to produce the same response. Maximal inducible LH concentrations were lowest (mean = 7.7 +/- 2.5 [SE] ng/ml) for pregnant wapiti, and the magnitude of the response decreased exponentially (r2 = 0.98, p = 0.002, SEb = 0.65) during gestation. Although the magnitude of the response declined over time, maximal release consistently occurred at the same dose (2 micrograms/50 kg BW) (treatment x trial interaction, p = 0.53). We conclude from these studies that the amount of LH released in response to a given dose of GnRH analog depends on reproductive status.(ABSTRACT TRUNCATED AT 250 WORDS)

Colorimetric determination of DNase I activity with a DNA-methyl green substrate

A simple, high throughput, and precise assay was developed for quantification of deoxyribonuclease I (DNase; IUB 3.1.21.1) activity. The method was adapted from the procedure devised by Kurnick which employs a substrate comprised of highly polymerized native DNA complexed with methyl green. Hydrolysis of the DNA produced unbound methyl green and a decrease in the absorbance of the solution at 620 nm. By adjusting the time and temperature of the reaction, the assay permits quantification of DNase activity over a wide concentration range (0.4 to 8900 ng/ml). Samples and standards were added to the substrate in microtiter plates and were incubated for 1-24 h at 25-37 degrees C to achieve the desired assay range. The DNase activity of the samples was interpolated from a standard curve generated with Pulmozyme recombinant human deoxyribonuclease I (rhDNase). Interassay precision was less than 12% CV and recovery was within 100 +/- 11%. Activity determination by the DNA-methyl green method correlated well with that determined by the widely used "hyperchromicity" method originated by Kunitz, which is based on the increase in absorbance at 260 nm upon hydrolysis of DNA. The DNA-methyl green assay was simpler and more versatile than the hyperchromicity method and was used to characterize the activity of rhDNase and DNase isolated from human urine.

Late leukemic relapse 10 years from diagnosis in a child on recombinant human growth hormone

A 12 year-old girl developed a late relapse of acute lymphoblastic leukaemia (ALL) 10 years from first presentation. Initial chemotherapy included vincristine, methotrexate, prednisolone, and L-asparaginase with cranial radiotherapy (18 Gy) for central nervous system prophylaxis. Documented growth failure led to recombinant human growth hormone (rhGH) replacement therapy being instituted in May 1989, 6 years from end of therapy and 2 years prior to relapse. Three independent experiments demonstrated no increased cell proliferation in vitro when the patient's thawed cryopreserved fresh leukemic cells were incubated with rhGH. However, a pre-T ALL cell line (PER-255) consistently demonstrated enhanced proliferation when incubated with rhGH (132.1 +/- 13.4%, P < 0.01). Growth hormone has been associated with an increased incidence of leukemia and may be implicated in the late relapse of this child. The use of growth hormone in children with a past history of ALL needs to be examined critically in the light of the potential risk of inducing leukemic relapse.

Long-term stability after inferior maxillary repositioning by miniplate fixation

Nineteen patients underwent Le Fort I osteotomy and inferior maxillary repositioning. Miniplates were used to maintain the maxilla in its new position. The patients were followed from 12 to 58 months, postoperatively. Fourteen patients were considered to be stable over the long term. Five patients had a long-term relapse of more than 30%. A tendency towards greater relapse was seen in patients with more than 5 mm inferior repositioning, and in patients who had concurrent segmental osteotomies of the maxilla. In spite of the use of miniplates, there continues to be an element of unpredictability with regard to vertical relapse after inferior maxillary repositioning, and this may be related to soft-tissue influences.

An antibody capture bioassay (ACB) for DNase in human serum samples

A novel assay for antibody captured bioactivity (ACB) has been developed to quantitate deoxyribonuclease I (DNase) in human serum samples. The procedure is simple, sensitive, reproducible and has a high throughput. Serum samples are diluted a minimum of 1/4 and assayed in 96-well microtiter plates coated with polyclonal antibodies specific to DNase. The serum is removed from the wells, the plates are washed and the antibody bound DNase is incubated at 37 degrees C with a DNA-methyl green substrate. The assay is sensitive to 0.8 ng/ml with a range to 10 +/- 2 ng/ml, depending upon the time of incubation (48 +/- 2 h). The recovery of rhDNase spiked into human serum samples averaged 84.4% +/- 6.7% in sera diluted 1/4 and 97.8% +/- 7.2% at a 1/8 serum dilution. Intra-assay precision ranged from 3.0 to 7.5% coefficient of variation (% CV) and interassay precision ranged from 5.0 to 10.2% CV for spiked serum controls. Endogenous DNase concentrations in 27 normal human sera were found to range from < 2.0 to 11.4 ng/ml. Endogenous DNase-like activity was found in Cynomolgus and Rhesus monkey sera; this activity diluted linearly and did not interfere with accurate quantitation of added rh DNase. No endogenous DNase-like activity could be detected in ten Sprague-Dawley rat sera. Bovine pancreatic DNase was found to have only very low cross-reactivity in this assay system. The ACB assay format can potentially be applied to the quantitation of other enzymes in serum and other biological samples.

Intraoral infantile hemangiopericytoma: literature review and addition of a case

A rapidly growing neoplasm in the buccal mucosa of a 4-month-old baby was excised. By light and electron microscopy the neoplasm had features that were similar to those described in infantile hemangiopericytoma, a rare neoplasm of vascular origin. By light microscopy the neoplasm was multilobular with highly proliferating round to spindle-shaped cells interspersed with numerous vascular spaces. Ultrastructurally, round to elongated cells with short processes, pinocytotic vesicles, reduplicated basal lamina, and basal lamina-like material were identified. Immunohistochemically the cells were weakly positive with antibodies to vimentin, focally positive with HHF-35, a smooth-muscle cell antibody, negative with antibodies to S-100 protein, T-200, neuron-specific enolase, neurofilaments, desmin, and cytokeratins 35BH11 and 34BE12. Blood vessels were positive with Ulexeuropaeuslectin, but tumor cells were negative. Reticulin stain decorated a delicate network of fibrils surrounding tumor cells and vascular spaces. Clinically the neoplasm did not recur and the baby has been disease free for more than 26 months. The difficulty of the histologic diagnosis of this neoplasm is discussed and the literature is reviewed, with special emphasis on lesions occurring in the oral cavity.