Prenatal phenotyping of fetal tubulinopathies: A multicenter retrospective case series

OBJECTIVE

Tubulinopathies refer to conditions caused by genetic variants in isotypes of tubulin resulting in defective neuronal migration. Historically, diagnosis was primarily via postnatal imaging. Our objective was to establish the prenatal phenotype/genotype correlations of tubulinopathies identified by fetal imaging.

METHODS

A large, multicenter retrospective case series was performed across nine institutions in the Fetal Sequencing Consortium. Demographics, fetal imaging reports, genetic screening and diagnostic testing results, delivery reports, and neonatal imaging reports were extracted for pregnancies with a confirmed molecular diagnosis of a tubulinopathy.

RESULTS

Nineteen pregnancies with a fetal tubulinopathy were identified. The most common prenatal imaging findings were cerebral ventriculomegaly (15/19), cerebellar hypoplasia (13/19), absence of the cavum septum pellucidum (6/19), abnormalities of the corpus callosum (6/19), and microcephaly (3/19). Fetal MRI identified additional central nervous system features that were not appreciated on neurosonogram in eight cases. Single gene variants were reported in TUBA1A (13), TUBB (1), TUBB2A (1), TUBB2B (2), and TUBB3 (2).

CONCLUSION

The presence of ventriculomegaly with cerebellar abnormalities in conjunction with additional prenatal neurosonographic findings warrants additional evaluation for a tubulinopathy. Conclusive diagnosis can be achieved by molecular sequencing, which may assist in coordination, prognostication, and reproductive planning.

Accuracy of Routine Prenatal Genetic Screening in Patients Referred for Genetic Counseling

OBJECTIVE

The American College of Obstetricians and Gynecologists (ACOG) guidelines recommend routine prenatal screening for genetic diseases that could affect the pregnancy. We sought to determine the rate of missed genetic information in the general obstetrician's routine prenatal genetic screening process.

STUDY DESIGN

This is a sequential case series of women referred for genetic counseling between March and August of 2015. Once identified, all women completed a personalized genetic history/exposure intake form (GHEF) created by our certified genetic counselors, followed by an in-person genetic counseling session with pedigree generation. The corresponding prenatal record was reviewed for genetic history obtained by the referring provider, most often utilizing the standardized ACOG prenatal intake form's genetic and family history sections. This information was then compared with that discovered in the GHEF and through the in-person genetic counseling session. Missed genetic information was defined as information discovered on the GHEF or during the in-person genetic counseling session which was not noted on the prenatal genetic screening document from the obstetric provider. Missing genetic information that lead to a change in clinical care, either through additional laboratory screening tests, fetal imaging or prenatal diagnostic testing through chorionic villus sampling, or amniocentesis was considered significant. We also assessed the study population as to maternal race, parity, and referral source. Statistical significance was assessed using Chi-squared testing with p < 0.05 identifying significance.

RESULTS

A total of 299 patients underwent genetic counseling. Of them, 57.5% patients were referred from private providers, 28.1% from academic faculty practice, and 14.4% from a federally funded clinic. Missed genetic information was discovered in 171/299 (57.2%) of patients in the genetic counseling process. Of these 171 patients, 28.7% were identified via the GHEF and 52.6% during the in-person genetic counseling session. Of the 171 patients who had new genetic information discovered, 73 (42.7%) findings were significant. There was no statistical difference in patient race or referring office setting in the occurrence of new information found.

CONCLUSION

In our population, genetic history obtained in the general obstetrician's office, regardless of practice type, missed genetic information in over half of cases with approximately 40% of that information leading to a subsequent change in clinical care. Developing a genetic intake form similar to our pregenetic counseling form, or modification/clarification of the "Family History and Genetic Screening" section within the standardized ACOG prenatal genetic history form, used at most practices in our region may decrease missed genetic information in the general obstetrician's office.

Experimental Bayesian Quantum Phase Estimation on a Silicon Photonic Chip

Quantum phase estimation is a fundamental subroutine in many quantum algorithms, including Shor's factorization algorithm and quantum simulation. However, so far results have cast doubt on its practicability for near-term, nonfault tolerant, quantum devices. Here we report experimental results demonstrating that this intuition need not be true. We implement a recently proposed adaptive Bayesian approach to quantum phase estimation and use it to simulate molecular energies on a silicon quantum photonic device. The approach is verified to be well suited for prethreshold quantum processors by investigating its superior robustness to noise and decoherence compared to the iterative phase estimation algorithm. This shows a promising route to unlock the power of quantum phase estimation much sooner than previously believed.

Chip-based quantum key distribution

Improvement in secure transmission of information is an urgent need for governments, corporations and individuals. Quantum key distribution (QKD) promises security based on the laws of physics and has rapidly grown from proof-of-concept to robust demonstrations and deployment of commercial systems. Despite these advances, QKD has not been widely adopted, and large-scale deployment will likely require chip-based devices for improved performance, miniaturization and enhanced functionality. Here we report low error rate, GHz clocked QKD operation of an indium phosphide transmitter chip and a silicon oxynitride receiver chip—monolithically integrated devices using components and manufacturing processes from the telecommunications industry. We use the reconfigurability of these devices to demonstrate three prominent QKD protocols—BB84, Coherent One Way and Differential Phase Shift—with performance comparable to state-of-the-art. These devices, when combined with integrated single photon detectors, pave the way for successfully integrating QKD into future telecommunications networks.

Quantum key distribution has not been widely adopted in part due to technical hurdles preventing it being fully integrated in classical communication networks. Here the authors report quantum key distribution between two photonic chips manufactured with state-of-the-art telecoms industry processes.

60 dB high-extinction auto-configured Mach-Zehnder interferometer

Imperfections in integrated photonics manufacturing have a detrimental effect on the maximal achievable visibility in interferometric architectures. These limits have profound implications for further technological developments in photonics and in particular for quantum photonic technologies. Active optimization approaches, together with reconfigurable photonics, have been proposed as a solution to overcome this. In this Letter, we demonstrate an ultrahigh (>60  dB) extinction ratio in a silicon photonic device consisting of cascaded Mach-Zehnder interferometers, in which additional interferometers function as variable beamsplitters. The imperfections of fabricated beamsplitters are compensated using an automated progressive optimization algorithm with no requirement for pre-calibration. This work shows the possibility of integrating and accurately controlling linear-optical components for large-scale quantum information processing and other applications.

Effectiveness of seasonal influenza vaccine in preventing influenza primary care visits and hospitalisation in Auckland, New Zealand in 2015: interim estimates

Preliminary results for influenza vaccine effectiveness (VE) against acute respiratory illness with circulating laboratory-confirmed influenza viruses in New Zealand from 27 April to 26 September 2015, using a case test-negative design were 36% (95% confidence interval (CI): 11–54) for general practice encounters and 50% (95% CI: 20–68) for hospitalisations. VE against hospitalised influenza A(H3N2) illnesses was moderate at 53% (95% CI: 6–76) but improved compared with previous seasons.

Qubit entanglement between ring-resonator photon-pair sources on a silicon chip

Entanglement—one of the most delicate phenomena in nature—is an essential resource for quantum information applications. Scalable photonic quantum devices must generate and control qubit entanglement on-chip, where quantum information is naturally encoded in photon path. Here we report a silicon photonic chip that uses resonant-enhanced photon-pair sources, spectral demultiplexers and reconfigurable optics to generate a path-entangled two-qubit state and analyse its entanglement. We show that ring-resonator-based spontaneous four-wave mixing photon-pair sources can be made highly indistinguishable and that their spectral correlations are small. We use on-chip frequency demultiplexers and reconfigurable optics to perform both quantum state tomography and the strict Bell-CHSH test, both of which confirm a high level of on-chip entanglement. This work demonstrates the integration of high-performance components that will be essential for building quantum devices and systems to harness photonic entanglement on the large scale.

Scalable photonic devices for quantum information processing require on-chip quantum states engineering. Here the authors report the creation of entangled photon pairs on a silicon-on-insulator chip by integrating resonant photon sources, spectral demultiplexers and reconfigurable optics in a single device.

Interim estimates of the effectiveness of seasonal trivalent inactivated influenza vaccine in preventing influenza hospitalisations and primary care visits in Auckland, New Zealand, in 2014

We present preliminary results of influenza vaccine effectiveness (VE) in New Zealand using a case test-negative design for 28 April to 31 August 2014. VE adjusted for age and time of admission among all ages against severe acute respiratory illness hospital presentation due to laboratory-confirmed influenza was 54% (95% CI: 19 to 74) and specifically against A(H1N1)pdm09 was 65% (95% CI:33 to 81). For influenza-confirmed primary care visits, VE was 67% (95% CI: 48 to 79) overall and 73% (95% CI: 50 to 85) against A(H1N1)pdm09.

Interim estimates of the effectiveness of seasonal trivalent inactivated influenza vaccine in preventing influenza hospitalisations and primary care visits in Auckland, New Zealand, in 2014

We present preliminary results of influenza vaccine effectiveness (VE) in New Zealand using a case test-negative design for 28 April to 31 August 2014. VE adjusted for age and time of admission among all ages against severe acute respiratory illness hospital presentation due to laboratory-confirmed influenza was 54% (95% CI: 19 to 74) and specifically against A(H1N1)pdm09 was 65% (95% CI:33 to 81). For influenza-confirmed primary care visits, VE was 67% (95% CI: 48 to 79) overall and 73% (95% CI: 50 to 85) against A(H1N1)pdm09.

Reference-frame-independent quantum-key-distribution server with a telecom tether for an on-chip client

We demonstrate a client-server quantum key distribution (QKD) scheme. Large resources such as laser and detectors are situated at the server side, which is accessible via telecom fiber to a client requiring only an on-chip polarization rotator, which may be integrated into a handheld device. The detrimental effects of unstable fiber birefringence are overcome by employing the reference-frame-independent QKD protocol for polarization qubits in polarization maintaining fiber, where standard QKD protocols fail, as we show for comparison. This opens the way for quantum enhanced secure communications between companies and members of the general public equipped with handheld mobile devices, via telecom-fiber tethering.

Comparative study of a low-Z cone-beam computed tomography system

Computed tomography images have been acquired using an experimental (low atomic number (Z) insert) megavoltage cone-beam imaging system. These images have been compared with standard megavoltage and kilovoltage imaging systems. The experimental system requires a simple modification to the 4 MeV electron beam from an Elekta Precise linac. Low-energy photons are produced in the standard medium-Z electron window and a low-Z carbon electron absorber located after the window. The carbon electron absorber produces photons as well as ensuring that all remaining electrons from the source are removed. A detector sensitive to diagnostic x-ray energies is also employed. Quantitative assessment of cone-beam computed tomography (CBCT) contrast shows that the low-Z imaging system is an order of magnitude or more superior to a standard 6 MV imaging system. CBCT data with the same contrast-to-noise ratio as a kilovoltage imaging system (0.15 cGy) can be obtained in doses of 11 and 244 cGy for the experimental and standard 6 MV systems, respectively. Whilst these doses are high for everyday imaging, qualitative images indicate that kilovoltage like images suitable for patient positioning can be acquired in radiation doses of 1-8 cGy with the experimental low-Z system.

Decoupling initial electron beam parameters for Monte Carlo photon beam modelling by removing beam-modifying filters from the beam path

A new method is presented to decouple the parameters of the incident e(-) beam hitting the target of the linear accelerator, which consists essentially in optimizing the agreement between measurements and calculations when the difference filter, which is an additional filter inserted in the linac head to obtain uniform lateral dose-profile curves for the high energy photon beam, and flattening filter are removed from the beam path. This leads to lateral dose-profile curves, which depend only on the mean energy of the incident electron beam, since the effect of the radial intensity distribution of the incident e- beam is negligible when both filters are absent. The location of the primary collimator and the thickness and density of the target are not considered as adjustable parameters, since a satisfactory working Monte Carlo model is obtained for the low energy photon beam (6 MV) of the linac using the same target and primary collimator. This method was applied to conclude that the mean energy of the incident e- beam for the high energy photon beam (18 MV) of our Elekta SLi Plus linac is equal to 14.9 MeV. After optimizing the mean energy, the modelling of the filters, in accordance with the information provided by the manufacturer, can be verified by positioning only one filter in the linac head while the other is removed. It is also demonstrated that the parameter setting for Bremsstrahlung angular sampling in BEAMnrc ('Simple' using the leading term of the Koch and Motz equation or 'KM' using the full equation) leads to different dose-profile curves for the same incident electron energy for the studied 18 MV beam. It is therefore important to perform the calculations in 'KM' mode. Note that both filters are not physically removed from the linac head. All filters remain present in the linac head and are only rotated out of the beam. This makes the described method applicable for practical usage since no recommissioning process is required.

Hepatic stellate cells: role in microcirculation and pathophysiology of portal hypertension

Accumulating evidence suggests that stellate cells are involved in the regulation of the liver microcirculation and portal hypertension. Activated hepatic stellate cells have the necessary machinery to contract or relax in response to a number of vasoactive substances. Because stellate cells play a role in both fibrosis and portal hypertension, they are currently regarded as therapeutic targets to prevent and treat the complications of chronic liver disease.

Activation of ATP-ubiquitin-dependent proteolysis in skeletal muscle in vivo and murine myoblasts in vitro by a proteolysis-inducing factor (PIF)

Loss of skeletal muscle is a major factor in the poor survival of patients with cancer cachexia. This study examines the mechanism of catabolism of skeletal muscle by a tumour product, proteolysis-inducing factor (PIF). Intravenous administration of PIF to normal mice produced a rapid decrease in body weight (1.55 +/- 0.12 g in 24 h) that was accompanied by increased mRNA levels for ubiquitin, the Mr 14 000 ubiquitin carrier-protein, E2, and the C9 proteasome subunit in gastrocnemius muscle. There was also increased protein levels of the 20S proteasome core and 19S regulatory subunit, detectable by immunoblotting, suggesting activation of the ATP-ubiquitin-dependent proteolytic pathway. An increased protein catabolism was also seen in C(2)C(12)myoblasts within 24 h of PIF addition with a bell-shaped dose-response curve and a maximal effect at 2-4 nM. The enhanced protein degradation was attenuated by anti-PIF antibody and by the proteasome inhibitors MG115 and lactacystin. Glycerol gradient analysis of proteasomes from PIF-treated cells showed an elevation in chymotrypsin-like activity, while Western analysis showed a dose-related increase in expression of MSSI, an ATPase that is a regulatory subunit of the proteasome, with a dose-response curve similar to that for protein degradation. These results confirm that PIF acts directly to stimulate the proteasome pathway in muscle cells and may play a pivotal role in protein catabolism in cancer cachexia.

Hookworm burden reductions in BALB/c mice vaccinated with recombinant Ancylostoma secreted proteins (ASPs) from Ancylostoma duodenale, Ancylostoma caninum and Necator americanus

Vaccination of mice with alum-precipitated recombinant Ancylostoma secreted protein-1 from the canine hookworm Ancylostoma caninum (Ac-ASP-1) results in protection against A. caninum larval challenge. Vaccine protection is manifested by host reductions in hookworm burden compared to control mice. The goal of this study was to determine whether ASP antigens cloned and expressed from different hookworm species will cross protect against A. caninum larval challenge. Cross-species protection against A. caninum challenge infections was observed with immunizations using recombinant ASP-1 from the human hookworms Ancylostoma duodenale and Necator americanus. However, the degree of protection was proportional to the extent of amino acid sequence homology between the ASP immunogen used for vaccination and the Ac-ASP-1 produced by the challenge larval strain. Vaccine protection was noted to decrease significantly as amino acid sequence homologies diverged 10% or more. It was also determined that Ac-ASP-2, a molecule cloned from A. caninum having 55% amino acid sequence homology to the C-terminus of Ac-ASP-1, did not elicit vaccine protection. These observations were partly reflected in the titer of antibodies that recognize Ac-ASP-1. The studies reported here will help to design immunogenic peptide vaccines based on the sequence divergence of hookworm ASPs.

The role of phosphatidic acid in platelet-derived growth factor-induced proliferation of rat hepatic stellate cells

Platelet-derived growth factor (PDGF) is the most potent mitogen for hepatic stellate cells (HSCs) in vitro. The aim of this study was to investigate the role of the lipid-derived second messenger phosphatidic acid (PA) in mediating this effect and, in particular, to determine its interaction with the extracellular signal-regulated kinase (ERK) cascade. HSCs were isolated from rat livers. PA production was determined by lipid extraction and thin-layer chromatography (TLC) after prelabeling cells with [(3)H]myristate. ERK activity was measured by an in vitro kinase assay after immunoprecipitation. Mitogenic concentrations of PDGF, but not those of the relatively less potent mitogen, transforming growth factor alpha (TGF-alpha), stimulated the sustained production of PA from HSCs. Exogenous PA stimulated HSC proliferation and a sustained increase in ERK activity, and proliferation was completely blocked by the inhibition of ERK activation with PD98059. The stimulation of ERK by PDGF was of a similar magnitude but more sustained than that caused by TGF-alpha. These results suggest that the potent mitogenic effect of PDGF in HSCs may be caused, in part, by the generation of PA and subsequently by a more sustained activation of ERK than occurs with less potent mitogens that do not induce the production of this lipid second messenger.

Stimulation of myofibrillar protein degradation and expression of mRNA encoding the ubiquitin-proteasome system in C(2)C(12) myotubes by dexamethasone: effect of the proteasome inhibitor MG-132

Addition of the synthetic glucocorticoid, dexamethasone (Dex) to serum-deprived C(2)C(12) myotubes elicited time- and concentration-dependent changes in N(tau)-methylhistidine (3-MH), a marker of myofibrillar protein degradation. Within 24 h, 100 nM Dex significantly decreased the cell content of 3-MH and increased release into the medium. Both of these responses had increased in magnitude by 48 h and then declined toward basal values by 72 h. The increase in the release of 3-MH closely paralleled its loss from the cell protein. Furthermore, Dex also decreased the 3-MH:total cell protein ratio, suggesting that myofibrillar proteins were being preferentially degraded. Incubation of myotubes with the peptide aldehyde, MG-132, an inhibitor of proteolysis by the (ATP)-ubiquitin (Ub)-dependent proteasome, prevented both the basal release of 3-MH (>95%) and the increased release of 3-MH into the medium in response to Dex (>95%). Northern hybridization studies demonstrated that Dex also elicited similar time- and concentration-dependent increases in the expression of mRNA encoding two components (14 kDa E(2) Ub-conjugating enzyme and Ub) of the ATP-Ub-dependent pathway. The data demonstrate that Dex stimulates preferential hydrolysis of myofibrillar proteins in C(2)C(12) myotubes and suggests that the ATP-Ub-dependent pathway is involved in this response.

Potential intracellular targets for anabolic/anti-catabolic therapies

The intracellular signalling pathways controlling muscle protein synthesis and proteolysis are potential targets for anabolic/anti-catabolic therapy. In this review, we consider both the potentiation of the effect of anabolic hormones and suppression of the catabolic action of cytokines. Potential candidates, in particular isoforms of the protein kinase C family, and their role in the control of ribosomal action and the ubiquitin-proteasome proteolytic system are discussed.

Translocation of protein kinase C isoforms in rat muscle in response to fasting and refeeding

Weanling rats were offered food ad libitum, or fasted for 18 h, or fasted and refed for times ranging from 5 to 30 min. Five protein kinase C (PKC) isoforms (alpha, epsilon, zeta, theta and mu) were detected in the hindlimb muscles by Western immunoblotting. PKC forms epsilon and theta were abundant in plantaris, but not in soleus muscle, and no difference in localization was detected between fed rats and those fasted for 18 h. PKC forms alpha and mu were affected by fasting and refeeding. PKC-mu was found only in the cytosolic fraction of the plantaris muscle of the fasted animal, but in the fully-fed animals it was also associated with the membrane fraction. The pattern of localization observed in the fully-fed state was restored in the fasted rats by 20 min refeeding. In contrast, PKC-alpha was not detected in the cytosolic fraction of the plantaris in fasted animals but rapidly reappeared there on refeeding, being restored to 20% and 80% of the fed value within 5 and 30 min of refeeding respectively. The timing of these changes was correlated with the increase in serum insulin concentration, which was significantly elevated above the fasted value by 5 min and at subsequent times. These data suggest a possible role for PKC isoforms alpha and mu in the metabolic changes that occur in skeletal muscle on transition between the fasted and the fed state.

Mechanism of muscle protein degradation induced by a cancer cachectic factor

A proteolysis-inducing factor (PIF) isolated from a cachexia-inducing murine tumour (MAC16) produced a decrease in body weight (1.6 g, P < or = 0.01 compared with control subjects) within 24 h after i.v. administration to non-tumour-bearing mice. Weight loss was associated with significant decreases in the weight of the spleen and soleus and gastrocnemius muscles, with no effect on the weight of the heart or kidney and with an increase in weight of the liver. Protein degradation in isolated soleus muscle was significantly increased in mice bearing the MAC16 tumour. To define which proteolytic pathways contribute to this increase, soleus muscles from mice bearing the MAC16 tumour and non-tumour-bearing animals administered PIF were incubated under conditions that modify different proteolytic systems. In mice bearing the MAC16 tumour, there were increases in both cathepsin B and L, and the Ca2+-dependent lysosomal and ATP-dependent pathways were found to contribute to the increased proteolysis; whereas, in PIF-injected animals, there was activation only of the ATP-dependent pathway. Further studies in mice bearing the MAC16 tumour have provided evidence for increased levels of ubiquitin-conjugated proteins and increased mRNA levels for the 14 kDa ubiquitin carrier protein E2 and the C9 proteasome subunit in gastrocnemius muscle, suggesting activation of the ATP-ubiquitin-dependent proteolytic pathway. A monoclonal antibody to PIF attenuated the enhanced protein degradation in soleus muscle from mice bearing the MAC16 tumour, confirming that PIF is responsible for the loss of skeletal muscle in cachectic mice.

Growth and metabolism of fetal and maternal muscles of adolescent sheep on adequate or high feed intake: possible role of protein kinase C-alpha in fetal muscle growth

From days 4-104 of pregnancy, adolescent sheep, weighing 43.7 (SE 0.87) kg were offered a complete diet at two different intakes (approximately 5 or 15 kg/week) designed to meet slightly, or well above, maternal maintenance requirements. The fetal and maternal muscles were taken on day 104 of pregnancy and analysed for total DNA, RNA and protein. Ewes offered a high intake to promote rapid maternal weight gain, weighed more (76.5 (SE 4.5) v 50.0 (SE 1.7) kg) and had muscles with a greater fresh weight, whilst their fetuses had smaller muscles, than those fed at a lower intake. Plantaris muscle of the ewes fed at the high intake contained more RNA and protein; again the opposite situation was found in the fetal muscle. On the higher maternal intakes, the DNA, RNA and protein contents of the fetal plantaris muscle were less than in fetuses of ewes fed at the lower intake. To investigate the possible mechanisms involved in this decrease in fetal muscle mass, cytosolic and membrane-associated muscle proteins were subjected to Western immunoblotting with antibodies to nine isoforms of protein kinase C (PKC), a family of enzymes known to play an important role in cell growth. Five PKC isoforms (alpha, epsilon, theta, mu, zeta) were identified in fetal muscle. One of these, PKC-alpha was located predominantly in the cytosolic compartment in the smaller fetuses of the ewes fed at a high plane of nutrition, but was present to a greater extent in the membranes of the more rapidly growing fetuses of the ewes fed at the lower intake. This was the only isoform to demonstrate nutritionally related changes in it subcellular compartmentation suggesting that it may mediate some aspects of the change in fetal growth rate.

Signalling pathways regulating protein turnover in skeletal muscle

The protein content of skeletal muscle is determined by the relative rates of synthesis and degradation which must be regulated coordinately to maintain equilibrium. However, in conditions such as fasting where amino acids are required for gluconeogenesis, or in cancer cachexia, this equilibrium is disrupted and a net loss of protein ensues. This review, utilising studies performed in several situations, summarizes the current state of knowledge on the possible signalling pathways regulating protein turnover in skeletal muscle and highlights areas for future work.

Regulation of phospholipase D in L6 skeletal muscle myoblasts. Role of protein kinase c and relationship to protein synthesis

The addition of vasopressin or 12-O-tetradecanoylphorbol-13-acetate (TPA) to prelabeled L6 myoblasts elicited increases in [14C]ethanolamine release, suggesting the activation of phospholipase D activity or activities. While the effects of both agonists on intracellular release were rapid and transient, when extracellular release of [14C]ethanolamine was measured, the effect of vasopressin was again rapid and transient, whereas that of TPA was delayed but sustained. Effects of both agonists on intra- and extracellular release were inhibited by the protein kinase C (PKC) inhibitor, Ro-31-8220, and PKC down-regulation by preincubation with TPA. The formation of phosphatidylbutanol elicited by vasopressin and TPA mirrored their effects on extracellular [14C]ethanolamine release in that the former was transient, whereas the latter was sustained. Responses to both agonists were abolished by PKC down-regulation. When protein synthesis was examined, the stimulation of translation by TPA and transcription by vasopressin were inhibited by Ro-31-8220. In contrast, down-regulation of PKC inhibited the synthesis response to TPA but not vasopressin. Furthermore, following down-regulation, the effect of vasopressin was still blocked by the PKC inhibitors, Ro-31-8220 and bisindolylmaleimide. Analysis of PKC isoforms in L6 cells showed the presence of alpha, epsilon, delta, mu, iota, and zeta. Down-regulation removed both cytosolic (alpha) and membrane-bound (epsilon and delta) isoforms. Thus, the elevation of phospholipase D activity or activities induced by both TPA and vasopressin and the stimulation of translation by TPA involves PKC-alpha, -epsilon, and/or -delta. In contrast, the increase in transcription elicited by vasopressin involves mu, iota, and/or zeta. Hence, although phospholipase D may be linked to increases in translation elicited by TPA, it is not involved in the stimulation of transcription by vasopressin.

Insulin and insulin-like growth factor-I responsiveness and signalling mechanisms in C2C12 satellite cells: effect of differentiation and fusion

In proliferating C2C12 myoblasts, serum and physiological concentrations of insulin and IGF-I stimulated protein synthesis and RNA accretion. After fusion, the multinucleated myotubes remained responsive to serum but not to insulin or IGF-I, even though both insulin and type-I IGF receptor mRNAs increased in abundance. Protein synthetic responses to insulin and IGF-I in myoblasts were not inhibited by dexamethasone, ibuprofen or Ro-31-8220, thus phospholipase A2, cyclo-oxygenase and protein kinase C did not appear to be involved in the signalling mechanisms. Neither apparently were polyphosphoinositide-specific phospholipase C or phospholipase D since neither hormone increased inositol phosphate, phosphatidic acid, choline or phosphatidylbutanol production. Only the phosphatidylinositol-3-kinase inhibitor, wortmannin, and the 70 kDa S6-kinase inhibitor, rapamycin, wholly or partially blocked the effects of insulin and IGF-I on protein synthesis. 2-deoxyglucose uptake remained responsive to insulin and IGF-I after fusion and was also inhibited by wortmannin. The results suggest that the loss of responsiveness after fusion is not due to loss of receptors, but to the uncoupling of a post-receptor pathway, occurring after the divergence of the glucose transport and protein synthesis signalling systems, and that, if wortmannin acts at a single site, this is prior to that point of divergence.

N tau-methylhistidine turnover in skeletal muscle cells measured by GC-MS

A method that employs gas chromatography-mass spectrometry has been developed to measure N tau-methylhistidine (3-methylhistidine; 3-MH) synthesis and release from skeletal muscle myotubes in vitro. It shows excellent linearity (0.9999) over the range studied (0-4 nmol), high recovery (92.6%), and low coefficient of variation (1.6%). 3-MH release from myotubes was essentially linear over a 96-h incubation, whereas the loss of 3-MH from cell protein accelerated with increasing time, an effect due, at lest in part, to decreasing rates of total protein synthesis. When incubated in either glutamine-free or methionine-free medium for 48 h, 3-MH in cell protein and appearing in the medium were greatly reduced compared with the 48-h controls, suggesting that hypertrophy was greatly reduced. Similar but lesser trends were observed with adenosine 3',5' -cyclic monophosphate. In contrast, 12-O-tetradecanoylphorbol-13-acetate (TPA) appeared to both stimulate 3-MII synthesis and inhibit its release during a 48-h incubation. The development of this method facilitates detailed investigation into the mechanisms through which agents such as TPA regulate myofibrillar protein degradation.

Cyclic AMP stimulates protein synthesis in L6 myoblasts and its effects are additive to those of insulin, vasopressin and 12-0-tetradecanoylphorbol-13-acetate. Possible involvement of mitogen activated protein kinase

The role of cyclic AMP as a second messenger in the stimulation of protein synthesis and the potential involvement of mitogen activated protein (MAP) kinase in this response was studied in L6 myoblasts. Dibutyryl-cAMP (dbt-cAMP) increased protein synthesis at 90 min and 6 h in a concentration-dependent manner. The responses at 90 min were probably mediated by increased translation as they were not blocked by actinomycin D; effects at 6 h were accompanied by increases in RNA content implying a transcriptional component. 100 nM 12-0-tetradecanoylphorbol-13-acetate (TPA), 1 nM Insulin (90 min incubations) and 100 nM vasopressin (6 h incubation) also increased protein synthesis and these responses were additive with those of 500 micron dbt-cAMP. Responses to forskolin were similar to dbt-cAMP whilst 1,9-dideoxyforskolin had no effect. Cell extracts immunoblotted with MAP kinase antibody showed bands corresponding to approx. 42, 44, 54 and 83 kDa. 500 micron dbt-cAMP elicited an increase in activity of both the 42 and 44 kDa bands when assayed by the 'in gel' method and a similar response was also observed with forskolin. TPA and vasopressin also stimulated the activity of these two isoforms, but had no significant additive or inhibitory effects when added in combination with 500 micron dbt-cAMP. In contrast, although 1 nM insulin alone had no effect, a synergistic response in terms of MAP kinase activation was observed in the presence of dbt-cAMP. The data demonstrate that cAMP stimulates protein synthesis in L6 cells and suggest a role for MAP kinase in this event.

Measurement of protein degradation by release of labelled 3-methylhistidine from skeletal muscle and non-muscle cells

The rates of [3H]N(tau)-methylhistidine (3-MH) accumulation in the medium, following pulse labelling of cells for 48 h with [3H]methionine, were used to measure myofibrillar protein degradation. In fused C2C12 myotubes, incubation for 24 or 48 h after the labelling period gave rates of myofibrillar degradation of 38 and 42%/day. In a leucine free medium, these rates were similar; 40 and 47%/day, respectively. Using identical conditions +/- leucine, but in the absence of [3H]-methionine, rates of protein accretion and synthesis over 24-48 h were measured. From these data, rates of total protein degradation were calculated by difference and were similar to myofibrillar degradation rates. We have used the same pulse labelling protocol to assess whether the method is applicable to non-muscle cell lines based on the knowledge that 3T3 fibroblasts contain actin in the cytoskeleton. 3-MH was detected both in protein and upon its release into the medium. Actin degradation measured over a 48 h period gave a value half that obtained for total degradation, but the results suggest that the release of 3-MH by fibroblasts in vivo could be appreciable. The development of this methodology should provide a useful tool to investigate signalling mechanisms regulating actin degradation in a variety of cell types.

Stimulation of protein and DNA synthesis in mouse C2C12 satellite cells: evidence for phospholipase D-dependent and -independent pathways

In C2C12 myoblasts, 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulated a phospholipase D (PLD) to degrade phosphatidylcholine (PC) as measured by the release of choline and an increase in the formation of phosphatidic acid (PA) (or phosphatidylbutanol [PtdBuOH] in the presence of 0.5% butanol). Exogenous PLD also stimulated choline release, PA and PtdBuOH formation. The protein kinase C (PKC) inhibitor, Ro-31-8220, and PKC downregulation significantly inhibited the effects of TPA but Ro-31-8220 had no effect on PLD action. Neither basic Fibroblast Growth Factor (bFGF) or Epidermal Growth Factor (EGF) increased PLD activity. All agonists stimulated protein synthesis during both a 90 min and a 6 hr incubation and increased RNA accretion after 6 hr. The response at 90 min was not inhibited by the transcription inhibitor, actinomycin D. Ro-31-8220 and PKC downregulation significantly inhibited all the effects of TPA. In contrast, Ro-31-8220 significantly inhibited the increase in RNA accretion elicited by PLD but had no effect on the ability of agonists other than TPA to enhance protein synthesis. All agonists also stimulated thymidine incorporation into DNA. The effects of EGF, bFGF, and PLD were rapid and transient whereas that of TPA was delayed and sustained. Ro-31-8220 and PKC downregulation significantly inhibited the response due to TPA. Furthermore, Ro-31-8220 also significantly inhibited the effects elicited by EGF and PLD but not that induced by bFGF. In differentiated myotubes, TPA and PLD, but not bFGF or EGF, again stimulated choline release and PtdBuOH formation. However, all agents failed to stimulate protein synthesis and RNA accretion. The data demonstrate the presence in C2C12 myoblasts, but not differentiated myotubes, of both a PLD-dependent and PLD-independent pathway(s) leading to the stimulation of protein synthesis, RNA accretion, and DNA synthesis.

Evidence that protein kinase C and mitogen activated protein kinase are not involved in the mechanism by which insulin stimulates translation in L6 myoblasts

Insulin stimulated a concentration-dependent increase in protein synthesis in L6 myoblasts which was significant at 1 nM. This response was not prevented by the transcription inhibitor, actinomycin D. The protein kinase C (PKC) inhibitor, Ro-31-8220, and downregulation of PKC by prolonged incubation of cells with 12-O-tetradecanoylphorbol-13-acetate (TPA), had no effect on the ability of insulin to stimulate protein synthesis whilst completely blocking the response to TPA. In contrast, insulin failed to enhance protein synthesis significantly in the presence of either ibuprofen, a selective cyclooxygenase inhibitor or rapamycin, an inhibitor of the 70 kDa S6 kinase. When cell extracts were prepared and assayed for total myelin basic protein kinase activity, a stimulatory effect of insulin was not observed until the concentration approached 100-fold (i.e. 100 nM) that required to elicit increases in protein synthesis. Upon fractionation on a Mono-Q column, 100 nM insulin increased the activity of 3 peaks which phosphorylated myelin basic protein. Two of these peaks were identified as the 42 and 44 kDa forms of Mitogen Activated Protein (MAP) kinase by immunoblotting. In contrast, 1 nM insulin had no effect on the activity of these peaks. The data suggest that physiologically relevant concentrations of insulin do not stimulate translation in L6 cells through either PKC or the 42/44 kDa isoforms of MAP kinase and that this response is, at least in part, mediated through the activation of the 70 kDa S6 kinase by cyclooxygenase metabolites.

Stimulation of protein synthesis and phospholipase D activity by vasopressin and phorbol ester in L6 myoblasts

The effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) and vasopressin on protein synthesis and phospholipase D (PLD) activity were investigated in L6 myoblasts. TPA stimulated a concentration-dependent increase in protein synthesis (EC50 approx. 10 nM) during a 90 min incubation, but had no effect after 6 h. The maximum increase was about 15% and was mediated through changes in translation, as TPA had no effect on RNA accretion and the response was not prevented by actinomycin D. TPA also stimulated PLD activity as measured by an 8-fold increase in the formation of phosphatidylbutanol (PtdBuOH) and the release of choline (EC50 5-10 nM). In contrast to TPA, vasopressin stimulated protein synthesis (maximum increase 30%, EC50 approx. 10 nM) and RNA accretion after 6 h, but had no effect after 90 min. Vasopressin also increased PtdBuOH production 4-5-fold (EC50 approx. 0.5 nM) and choline release (EC50 approx. 1 nM). The addition of a highly purified preparation of PLD (2-10 units/ml) from Streptomyces sp. to L6 cells stimulated a concentration-dependent increase in choline release and protein synthesis after both 90 min (maximum stimulation 13%) and 6 h (maximum stimulation 12%). PLD also stimulated RNA accretion after 6 h but not 90 min. The data support a role for PLD in the regulation of protein synthesis in L6 cells.

Recruitment challenges in studying late-life depression: do community samples adequately represent depressed older adults?

Although research on late-life depression is burgeoning, little attention has been given to the sampling and recruitment obstacles encountered in trying to enlist the participation of older adults in such studies. In this article, the authors summarize the response rates of 15 recent epidemiological studies and 100 descriptive studies examining late-life depression among community-dwelling older adults. These studies excluded approximately 25-35% of potential participants. The authors present evidence suggesting that because depressed older adults may be especially likely to refuse research invitations, researchers may overlook or underestimate important correlates of depression. In addition, the authors describe several strategies for enhancing recruitment efforts.

Recruitment challenges in studying late-life depression: do community samples adequately represent depressed older adults?

Although research on late-life depression is burgeoning, little attention has been given to the sampling and recruitment obstacles encountered in trying to enlist the participation of older adults in such studies. In this article, the authors summarize the response rates of 15 recent epidemiological studies and 100 descriptive studies examining late-life depression among community-dwelling older adults. These studies excluded approximately 25-35% of potential participants. The authors present evidence suggesting that because depressed older adults may be especially likely to refuse research invitations, researchers may overlook or underestimate important correlates of depression. In addition, the authors describe several strategies for enhancing recruitment efforts.

Arachidonate activation of protein kinase C may be involved in the stimulation of protein synthesis by insulin in L6 myoblasts

Insulin stimulated protein synthesis in L6 myoblasts but did not increase the labelling of DAG or the release of phosphocholine from phosphatidylcholine. The DAG lipase inhibitor, RHC 80267, more than doubled the amount of label appearing in DAG but did not stimulate protein synthesis. Even in the presence of the DAG lipase inhibitor insulin failed to have any effect on DAG labelling, and conversely RHC 80267 did not modify the insulin-induced increase in protein synthesis. These results suggest that endogenous DAG production is not involved in the stimulation of protein synthesis by insulin. However, exogenous diacylglycerols (1-oleoyl-2-acetyl glycerol and 1-stearoyl-2-arachidonoyl glycerol) both stimulated protein synthesis in L6 myoblasts. The efficacy of the former (arachidonate-free) DAG suggested that their action was by activation of protein kinase C rather than by arachidonate release and prostaglandin formation. Ibuprofen, an inhibitor of cyclo-oxygenase failed to block the effects of insulin whereas a second cyclo-oxygenase inhibitor, indomethacin had only a partial inhibitory effect. The protein kinase C (PKC) inhibitor, RO-31-8220, totally blocked the effect of insulin. Since indomethacin is also recognised to inhibit phospholipase A2, the data suggests that insulin acts on protein synthesis in myoblasts by arachidonate activation of PKC.

Distinction between quality and quantity of problem-solving responses among depressed older women

The purpose of this project was to investigate the extent to which depressed and nondepressed community-dwelling older women differed in their problem-solving responses to vignettes describing problematic situations common in this population. Contrary to expectations, the depressed and nondepressed older women showed an equal capacity to follow traditional problem-solving steps. There were differences, however, in the quality of solutions generated for dealing with social isolation and interpersonal conflict as judged by peer evaluators. Further work is needed in understanding the components of effective problem solving most important for adjustment to real-life difficulties.

Oxytocin receptor concentrations, inositol phosphate turnover and prostaglandin release by endometrium from ewes induced to ovulate during the early post-partum period

Induction of ovulation early post partum in sheep is associated with a high incidence (30-40%) of premature luteolysis. The present study was designed to characterize oxytocin receptor levels, oxytocin-stimulated inositol phosphate (IP) turnover (second messenger) and oxytocin-stimulated prostaglandin F2 alpha (PGF2 alpha) release in the endometrium of post-partum ewes induced to ovulate 21 days after parturition and expected to exhibit a range of corpus luteal functions subsequently. Ovulation was induced on day 21 post partum using a controlled internal drug release device and pregnant mare serum gonadotrophin, and uterine tissues were collected on days 5, 10 or 15 of the cycle (n = 4/day). A further 12 ewes whose interval from previous parturition exceeded 150 days were similarly treated and acted as controls. Measurement of daily peripheral progesterone concentrations revealed that while all control ewes exhibited normal luteal function, abnormal luteal function was evident in two, two and one post-partum ewes studied on days 5, 10 and 15 of the cycle respectively. Oxytocin receptor binding was detected (by receptor-binding assay and in-vitro autoradiography) in the endometrium and myometrium of post-partum ewes at all three stages of the oestrous cycle but only at day 15 in control ewes. To determine IP turnover, 100 mg caruncular endometrium was incubated in duplicate for 2.5 h with 10 microCi [3H]inositol and treated with 0 or 2 mumol oxytocin/l for 30 min, then [3H]inositol mono-, bis- and trisphosphates were quantified.(ABSTRACT TRUNCATED AT 250 WORDS)

Doxorubicin interactions at the membrane: evidence for a biphasic modulation of inositol lipid metabolism

Doxorubicin, when incubated for 30 minutes with [32P]-labelled human erythrocyte membrane vesicles, produced an elevation of [32P]inositol-1,4,5-trisphosphate levels. The maximum rise was obtained with 10(-8) mol/l doxorubicin [132 (S.E. 13%) of control, n = 6, P = 0.001]. However, when the inositol lipids were examined, there was no evidence that doxorubicin stimulated the breakdown of [32P]phosphatidylinositol-4,5-bisphosphate under resting conditions, suggesting that the elevated levels of [32P]inositol 1,4,5-trisphosphate were not the result of the stimulation of phospholipase C. Instead, it was found that the dephosphorylation of inositol 1,4,5-trisphosphate by a 5'-phosphomonoesterase was partially inhibited by 10(-8) mol/l doxorubicin so that the rise in [32P]inositol 1,4,5-trisphosphate resulted from the inhibition of the breakdown of constitutively released [32P] inositol 1,4,5-trisphosphate. Similar data was also obtained with another aminoglycoside antibiotic, neomycin. The release of [32P] inositol 1,4-bisphosphate and [32P] inositol 1,4,5-trisphosphate and the breakdown of the inositol lipids in response to calcium (2.5 x 10(-4) and 10(-3) mol/l) stimulation was enhanced by doxorubicin (10(-6) to 10(-12) mol/l). These effects on resting and stimulated inositol lipid metabolism are discussed with reference to the paradoxical effects of doxorubicin to both stimulate and inhibit proliferation, according to concentration.

Facets of support related to well-being: quantitative social isolation and perceived family support in a sample of elderly women

The purpose of this study was to examine the independent and interactive relationships of measures of network embeddedness and perceived social support with mental and physical health measures from responses of a sample of 271 community-dwelling elderly women. Quantitative social isolation was measured as the co-occurrence of low network embeddedness with family and with friends. There was a threshold effect such that quantitatively isolated participants had poorer psychological well-being and functional health than did nonisolated participants. This effect was independent of perceived support levels. The pattern was different for perceived social support. Elderly women with low perceived family support had poorer psychological well-being regardless of perceived support from friends or network embeddedness. Implications are discussed for several unanswered questions in the social support literature, including possible interventions for the quantitatively isolated and for those with low levels of perceived support.

Effect of gastrin-releasing peptide on the secretion of mouse islet hormones in vitro

Collagenase-isolated mouse islets were incubated with gastrin-releasing peptide (GRP). At 5.6 mmol glucose/l. 10 nmol GRP/l increased the release of insulin (by 50%) and glucagon (by twofold), decreased the release of pancreatic polypeptide (by 35%), but did not significantly affect the release of somatostatin. At 16.7 mmol glucose/l, 10 nmol GRP/l increased glucagon release (by fivefold) and decreased pancreatic polypeptide release (by 46%), without significantly altering insulin and somatostatin release. GRP (200 nmol/l) did not affect insulin release by perifused mouse islets at 2.8 mmol glucose/l, but increased both first and second phase insulin release after a square wave increase in the glucose concentration to 11.1 mmol/l. At 5.6 mmol glucose/l, GRP (100 pmol/1-100 nmol/l) increased (by 50-70%) insulin release by the RINm5F clonal cell line. GRP did not affect glucose oxidation or the cyclic adenosine monophosphate content of RINm5F cells. However, the intracellular free Ca2+ concentration of RINm5F cells was rapidly and transiently increased by GRP (maximum increase of 64% about 10 s after exposure to 1 mumol GRP/l). The rise of intracellular free Ca2+ was approximately halved in the absence of extracellular Ca2+. The results suggest that GRP may contribute to the normal regulation of the endocrine pancreas. The insulin-releasing effect of GRP is mediated via increased cytosolic free Ca2+, derived both from an increased net influx of extracellular Ca2+ and from mobilization of intracellular Ca2+ stores.

Elevation of leukemic cell intracellular calcium by the ether lipid SRI 62-834

SRI 62-834 is a novel antineoplastic ether lipid which is currently undergoing a Phase 1 clinical trial in the United Kingdom. Its mechanism of action has not been defined. Incubation of 7.5 X 10(6)/ml HL-60 human myelomonocytic leukemia cells with between 10 and 50 microM SRI 62-834 brought about a concentration-dependent, biphasic rise in intracellular calcium, as measured by the calcium-sensitive fluorescent dye Quin-2 AM. Incubation with 30 microM SRI 62-834 elevated intracellular calcium from 110 to 415 nM after 10 min in a typical experiment; this concentration inhibited cell growth by greater than 90% (50% inhibition of growth was observed at 8 microM). The calcium channel blockers verapamil and prenylamine did not inhibit the SRI 62-834-induced elevation of intracellular calcium. Incubation of SRI 62-834 with K562 erythroblastic leukemia cells also brought about a rise in the intracellular calcium. The growth of K562 cells was less sensitive to SRI 62-834 (dose to produce 50% growth inhibition, 65 microM) compared to HL-60 cells, and significant intracellular calcium rises, which were monophasic, required greater than 40 microM SRI 62-834. At a concentration of SRI 62-834 which inhibited both HL-60 and K562 growth by 90% (30 and 140 microM, respectively) an equivalent rise in intracellular calcium was observed (circa 400 nM). Preincubation of HL-60 or K562 cells with 1 to 100 nM 12-O-tetradecanoylphorbol-13-acetate for 10 min prior to the addition of SRI 62-834 inhibited the rise in intracellular calcium in a concentration-dependent manner. It is suggested that SRI 62-834-induced changes in intracellular calcium may contribute to its cytotoxicity and that the rise is not due to an early and grossly disruptive effect of the agent on membrane structure.

Facets of support related to well-being: Quantitative social isolation and perceived family support in a sample of elderly women

The purpose of this study was to examine the independent and interactive relationships of measures of network embeddedness and perceived social support with mental and physical health measures from responses of a sample of 271 community-dwelling elderly women. Quantitative social isolation was measured as the co-occurrence of low network embeddedness with family and with friends. There was a threshold effect such that quantitatively isolated participants had poorer psychological well-being and functional health than did nonisolated participants. This effect was independent of perceived support levels. The pattern was different for perceived social support. Elderly women with low perceived family support had poorer psychological well-being regardless of perceived support from friends or network embeddedness. Implications are discussed for several unanswered questions in the social support literature, including possible interventions for the quantitatively isolated and for those with low levels of perceived support.