Mu opioid receptor-effector coupling and trafficking in dorsal root ganglia neurons

Morphine induces profound analgesic tolerance in vivo despite inducing little internalization of the mu opioid receptor (muOR). Previously proposed explanations suggest that this lack of internalization could either lead to prolonged signaling and associated compensatory changes in downstream signaling systems, or that the receptor is unable to recycle and resensitize and so loses efficacy, either mechanism resulting in tolerance. We therefore examined, in cultured neurons, the relationship between muOR internalization and desensitization in response to two agonists, D-Ala2, N-MePhe4, Gly5-ol-enkephalin (DAMGO) and morphine. In addition, we studied the chimeric mu/delta opioid receptor (mu/ partial differentialOR) which could affect internalization and desensitization in neurons. Dorsal root ganglia neurons from muOR knockout mice were transduced with an adenovirus expressing either receptor and their respective internalization, desensitization and trafficking profiles determined. Both receptors desensitized equally, measured by Ca2+ current inhibition, during the first 5 min of agonist exposure to DAMGO or morphine treatment, although the mu/partial differentialOR desensitized more extensively. Such rapid desensitization was unrelated to internalization as DAMGO, but not morphine, internalized both receptors after 20 min. In response to DAMGO the mu/partial differentialOR internalized more rapidly than the muOR and was trafficked through Rab4-positive endosomes and lysosomal-associated membrane protein-1-labeled lysosomes whereas the muOR was trafficked through Rab4 and Rab11-positive endosomes. Chronic desensitization of the Ca2+ current response, after 24 h of morphine or DAMGO incubation, was seen in the DAMGO, but not morphine-treated, muOR-expressing cells. Such persistence of signaling after chronic morphine treatment suggests that compensation of downstream signaling systems, rather than loss of efficacy due to poor receptor recycling, is a more likely mechanism of morphine tolerance in vivo. In contrast to the muOR, the mu/partial differentialOR showed equivalent desensitization whether morphine or DAMGO treated, but internalized further with DAMGO than morphine. Such ligand-independent desensitization could be a result of the observed higher rate of synthesis and degradation of this chimeric receptor.

Gamma camera scintigraphy of tumours using195mPt-cisplatin

Platinum enriched with 194Pt was irradiated for 4 days in NRG's TIRO 1 reactor, to produce (195m)Pt. Spectral analysis of the product was performed using a calibrated hyper pure germanium detector and its constituent radioisotopes were identified as (195m)Pt, 199Au and 192Ir. Using the detector's intrinsic efficiency calibration, their activities were estimated to be 1049, 133 and 5.8 MBq, respectively. The performance of the gamma camera was tested using quality control procedures recommended by the Institute of Physics and Engineering in Medicine (IPEM) and was found to be satisfactory. A torso phantom was used to determine the minimum detection limit (MDL) of (195m)Pt in a 2 cm diameter tumour using SPECT acquisitions (32 steps, 60 s per step). The MDL was found to be 8 ppm assuming an administered patient dose of 50 MBq and a total cisplatin dose of 105 mg. This work indicates that (195m)Pt-cisplatin is suitable for clinical scintigraphy and has led to the development of a clinical protocol that has been approved for a pilot study.

Do real time 'flu spotter rates warn us about impending emergency admissions and deaths?

This study aimed to determine how general practice influenza surveillance ('flu spotter) data related to hospital admissions and deaths in Scotland during the winter period. 'Flu spotter rates correlated well with influenza-related emergency admissions and deaths, and deaths from all causes, particularly during 'peak' influenza years. They may be used in a predictive model for influenza-related hospital admissions and deaths.

Functional coupling, desensitization and internalization of virally expressed mu opioid receptors in cultured dorsal root ganglion neurons from mu opioid receptor knockout mice

Although mu opioid receptors desensitize in various cell lines in vitro, the relationship of this change in signaling efficacy to the development of tolerance in vivo remains uncertain. It is clear that a system is needed in which functional mu opioid receptor expression is obtained in appropriate neurons so that desensitization can be measured, manipulated, and mutated receptors expressed in this environment. We have developed a recombinant system in which expression of a flag-tagged mu opioid receptor is returned to dorsal root ganglia neurons from mu opioid receptor knockout mice in vitro. Flow cytometry analysis showed that adenoviral-mediated expression of the amino-terminal flag-tagged mu opioid receptor in neurons resulted in approximately 1.3x10(6) receptors/cell. Many mu opioid receptor cell lines express a similar density of receptors but this is approximately 7x greater than the number of endogenous receptors expressed by matched wild-type neurons. Inhibition of the high voltage-activated calcium currents in dorsal root ganglia neurons by the mu agonist, D-Ala(2), N-MePhe(4), Gly(5)-ol-enkephalin (DAMGO), was not different between the endogenous and flag-tagged receptor at several concentrations of DAMGO used. Both receptors desensitized equally over the first 6 h of DAMGO pre-incubation, but after 24 h the response of the endogenous receptor to DAMGO had desensitized further than the flag- tagged receptor (71+/-3 vs 29+/-7% respectively; P<0.002), indicating less desensitization in neurons expressing a higher density of receptor. Using flow cytometry to quantify the percentage of receptors remaining on the neuronal cell surface, the flag-tagged receptor internalized by 17+/-1% after 20 min and 55+/-2% after 24 h of DAMGO. These data indicate that this return of function model in neurons recapitulates many of the characteristics of endogenous mu opioid receptor function previously identified in non-neuronal cell lines.

A mathematical model of CO2 variation in the ventilated neonate

A mathematical model of the variation of partial pressure of carbon dioxide in the arterial blood of a ventilated neonate is developed. The model comprises alveolar, arterial, pulmonary, venous and tissue compartments, with gas exchange in the lung determined by inspiration and expiration terms. Gas exchange is modelled through diffusion and convective transfer. Carbon dioxide is produced in the tissue by a metabolic term. Shunting is modelled by allowing blood flow to bypass the pulmonary compartment in which diffusion takes place. The model predicts changes in the carbon dioxide partial pressures that occur following abrupt changes in the ventilation settings, and show broad agreement with actual data obtained from novel sensing technology.

The specific absorbed dose constant: comparison of values published for 60Co photons

For the specific absorbed dose constant for 60Co photons, three values quoted directly in the literature and two derived indirectly from published information are reported. The three publications giving the direct values mentioned no medium of absorption, whereas the other two specify tissue. A database of the specific absorbed dose constant is generated for each of 14 media namely air, water, bone and 11 types of soft tissue. These values are consistent with the three directly quoted values plus one of the indirectly obtained values. Air is found to be unlikely as the medium for the first three; and appropriate media for these are suggested. For the other two values, the generated database suggests that one is too small to be accurate; while the other is correct for tissue (as stated in the publication). An apparent error of 10(3) is identified in one of the values directly quoted.

Relationship between lower limb symptoms and patterns of deep and superficial venous reflux on duplex ultrasonography

Background

There are inconsistent and sex-dependent relationships between lower limb symptoms and the presence and severity of trunk varicose veins on clinical examination. The relationship between lower limb symptoms and patterns of venous reflux on duplex ultrasonography were investigated.

Methods

This was a cross-sectional study of an age-stratified random sample of 1566 subjects (699 men and 867 women) aged 18–64 years selected from 12 family practices. Subjects completed a self-administered questionnaire regarding symptoms (heaviness/tension, a feeling of swelling, aching, restless legs, cramps, itching, tingling) and underwent duplex ultrasonographic examination of both legs. Reflux greater than 0·5 s was considered pathological.

Results

Isolated superficial reflux was significantly related to the presence of heaviness/tension (P &lt; 0·025, both legs) and itching (P = 0·002, left leg only) in women. Isolated deep venous reflux was not significantly related to any symptom in either leg in either sex. Combined superficial and deep reflux was related to a feeling of swelling (P = 0·02, both legs), cramps (P &lt; 0·005, left leg only) and itching (P &lt; 0·005, left leg only) in men, and aching (P = 0·03, right leg only) and cramps (P = 0·026, left leg only) in women.

Conclusion

Duplex ultrasonography may be superior to clinical examination alone in identifying patients whose lower limb symptoms are truly of venous origin and thus most likely to benefit from surgery.

Chronic venous insufficiency in the general population: clinical and duplex correlations

Background

If operations for chronic venous insufficiency (CVI) are to be rational and cost effective, the natural history needs to be understood and patients with early disease who will progress to advanced CVI and leg ulcer need to be identified. Published data have derived largely from selected referred hospital patients. The pattern of venous disease in the general population is unknown. The aim was to determine the prevalence of CVI in the general population and to correlate clinical features with the findings on duplex ultrasonography.

Methods

A cross-section of men and women aged 18–64 years randomly selected from 12 general practices were surveyed. Subjects were screened by questionnaire, examination, photography, blood tests and continuous-wave Doppler ultrasonography. Eight segments of the deep and superficial veins were assessed for reflux by means of duplex ultrasonography.

Results

Some 1566 patients were screened (867 women of mean age 44·8 years and 699 men of mean age 45·8 years), of whom 134 were diagnosed as having CVI (Basle classification): grade 1, 95; grade 2, 19; grade 3, ten. The age-adjusted prevalence for the whole series was 3·1 per cent (2·6 per cent in men, 3·4 per cent in women). The prevalence of CVI correlated closely with age, being 15·2 per cent in men aged over 50 years and 9·0 per cent in women aged above 50 years. Heaviness, tension, swelling, aching and itching were significantly commoner in patients with CVI than in the general population. CVI was significantly associated with reflux in all deep and superficial segments. The frequency of reflux in both superficial and deep segments increased with the clinical severity of disease (P = 0·01). In 48·1 per cent reflux was limited to the superficial system and was thus potentially remediable.

Conclusion

CVI was common in this relatively young population. Having established the frequency of CVI and its related pattern of reflux in the general population, this cohort provides a benchmark for clinical studies and will form the basis of further longitudinal epidemiological studies.

The use of associated particle timing based on the D + D reaction for imaging a solid object

Associated particle timing based on the D + D reaction has been applied for imaging a bulk sample, namely an aluminium box. The relatively low neutron energy, 2.8 MeV, allows a better spatial resolution from time-of-flight measurements. A combination of a Si detector for charged particles and an NaI(Tl) scintillator for inelastic-scatter gamma rays yielded an overall time resolution of 0.4 ns, giving a spatial resolution of better than 1 cm. A new reconstruction program was developed, yielding an image free from major artefacts.

Pure rotational spectra, structures, and hyperfine constants of OC-AuX (X = F, Cl, Br)

Rotational spectra of OC-AuX (X = F, Cl, Br) have been measured in the frequency range 5-21 GHz, using a pulsed jet cavity Fourier transform microwave spectrometer. The molecules were prepared by ablating Au metal with a Nd:YAG laser and allowing the vapor to react with CO plus a halide precursor contained in the Ar backing gas of the jets. For OC-AuCl and OC-AuBr these are the first high-resolution spectroscopic measurements; for OC-AuF these are the first observations of any kind. All three molecules are linear. Rotational constants, centrifugal distortion constants, and nuclear quadrupole coupling constants have been precisely evaluated. The geometries determined for all three molecules show CO bond lengths close to that of free CO, plus relatively long Au-C bonds. These results are corroborated by ab initio calculations, which have also produced Mulliken populations showing significant sigma-donation from CO to Au, plus some pi-back-donation from Au to CO. There are major changes in the Au, Cl, and Br nuclear quadrupole coupling constants when CO bonds to AuX, consistent with the formation of strong Au-C bonds. The structural properties of OC-AuF are somewhat different from those of OC-AuCl and OC-AuBr.

An economic evaluation of a chlorhexidine chip for treating chronic periodontitis: the CHIP (chlorhexidine in periodontitis) study

BACKGROUND

The authors previously suggested that an adjunctive, controlled-release chlorhexidine, or CHX, chip may reduce periodontal surgical needs at little additional cost. This article presents an economic analysis of the CHX chip in general dental practice.

METHODS

In a one-year prospective clinical trial, 484 chronic periodontitis patients in 52 general practices across the United States were treated with either scaling and root planing, or SRP, plus any therapy prescribed by treating, unblinded dentists; or SRP plus other therapy as above but including the CHX chip. Economic data were collected from bills, case report forms and 12-month treatment recommendations from blinded periodontist evaluators.

RESULTS

Total dental charges were higher for SRP + CHX chip patients vs. SRP patients when CHX chip costs were included (P = .027) but lower when CHX chip costs were excluded (P = .012). About one-half of the CHX chip acquisition cost was offset by savings in other charges. SRP + CHX chip patients were about 50 percent less likely to undergo surgical procedures than were SRP patients (P = .021). At the end of the trial, periodontist evaluators recommended similar additional procedures for both groups: SRP, about 46 percent; maintenance, about 37 percent; surgery, 56 percent for SRP alone and 63 percent for SRP + CHX chip.

CONCLUSIONS

Adjunctive CHX chip use for general-practice patients with periodontitis increased costs but reduced surgeries over one year. At study's end, periodontists recommended similar additional surgical treatment for both groups.

CLINICAL IMPLICATIONS

In general practice, routine use of the CHX chip suggests that costs will be partially offset by reduced surgery over at least one year.

Disruption of the Crithidia fasciculata KAP1 gene results in structural rearrangement of the kinetoplast disc

The mitochondrial DNA (kinetoplast DNA) in trypanosomatids exists as a highly organized nucleoprotein structure with the DNA consisting of thousands of interlocked circles. Four H1 histone-like proteins (KAP1, 2, 3 and 4) are associated with the kinetoplast DNA in the trypanosomatid Crithidia fasciculata. We have disrupted both alleles of the KAP1 gene in this diploid protozoan and shown that expression of the KAP1 protein is eliminated. The mutant strain is viable but has substantial rearrangement of the kinetoplast structure. Expression of the KAP1 protein from an episome restored expression of the KAP1 protein in the mutant strain and also restored a normal kinetoplast structure. These studies provide evidence that the KAP1 protein is involved in kinetoplast DNA organization in vivo but is nonessential for cell viability.

Agonist-, antagonist-, and inverse agonist-regulated trafficking of the delta-opioid receptor correlates with, but does not require, G protein activation

In this study, we explored the relationship between ligand-induced regulation of surface delta opioid receptors and G protein activation. G protein activation was assessed with [(35)S]guanosine-5'-O-(3-thio)triphosphate (GTP gamma S) binding assays conducted at both 37 and 0 degrees C. Ligand-independent (constitutive) activity of the delta-receptor was readily observed when the [(35)S]GTP gamma S binding assay was performed at 37 degrees C. We identified a new class of alkaloid inverse agonists (RTI-5989-1, RTI-5989-23, RTI-5989-25), which are more potent than the previously described peptide inverse agonist ICI-174864 (N,N-diallyl-Tyr-Aib-Aib-Phe-Leu). Treatment with these inverse agonists for 18 h caused up-regulation of surface receptors. Eighteen-hour treatment with etorphine resulted in approximately 90% loss of surface receptor, whereas fentanyl, diprenorphine, and morphine caused between 20 and 50% loss. The abilities of ligands to modulate [(35)S]GTP gamma S binding at 37 degrees C showed a strong correlation with their abilities to regulate surface receptor number (r(2) = 0.86). Interestingly, the ability of fentanyl to activate G proteins was markedly temperature sensitive. Fentanyl showed no stimulation of [(35)S]GTP gamma S binding at 0 degrees C but was as efficacious as etorphine, morphine, and diprenorphine at 37 degrees C. Neither the ligand-induced receptor increases nor decreases were perturbed by pertussis toxin pretreatment, suggesting that functional G proteins are not required for ligand-regulated delta-opioid receptor trafficking.

Prevalence and risk factors of chronic venous insufficiency

Venous disease in the legs occurs very commonly in the general population in Western countries. Around one third of women have trunk varices. A lower prevalence has been observed in men but some recent surveys have suggested that the occurrence in men may be comparable to that in women. The prevalence increases with age but the incidence of new cases appears to be constant throughout adult life. Open venous ulcers occur in about 0.3% of the adult population and a history of open or healed ulceration occurs in around 1%. The etiology of chronic venous disease in the legs is unknown. A genetic predisposition may be present but evidence for this and for a mode of inheritance is lacking. There is some suggestion that prolonged standing may be a risk factor but studies are open to considerable bias. In women, obesity and previous pregnancy has been associated with the presence of varicose veins but the evidence is inconsistent. There have been few well-conducted studies examining diet and bowel habit as a risk factor. The risk of ulceration is related to the severity of varicosities and venous insufficiency, and is increased following deep vein thrombosis. Much further research is required to investigate the cause of this common condition in the general population.

Lifestyle risk factors for lower limb venous reflux in the general population: Edinburgh Vein Study

BACKGROUND

Varicose veins occur commonly in the general population but the aetiology is not well established. Varicosities are associated frequently with reflux of blood in the leg veins due to valvular incompetence. Our aim was to determine in the general population which lifestyle factors were related to reflux and thus implicated in the aetiology of varicose veins.

METHODS

In the Edinburgh Vein Study, 1566 men and women aged 18-64 years were sampled randomly from the general population in the city of Edinburgh, Scotland, and had duplex scans to measure reflux in eight venous segments in each leg. A self-administered questionnaire enquired about occupation, mobility at work, smoking, obstetric history, dietary fibre intake and bowel habit. A bowel record form was completed subsequently.

RESULTS

In women, venous reflux was associated with decreased sitting at work (odds ratio [OR] = 0.76, 95% CI : 0.61-0.94), previous pregnancy (OR = 1.20, 95% CI : 0.93-1.54), and a lower prior use of oral contraceptives (OR = 0.84, 95% CI : 0.66-1.06). Mean body mass index was greater in women with superficial reflux compared to those with no reflux: 26.2 kg/m(2) (95% CI : 25.5-27.0) versus 25.2 kg/m(2) (95% CI : 24.8-25.6). On age adjustment, sitting at work remained related to reflux (OR = 0.78, 95% CI : 0.63-0.98) and prior use of oral contraceptives to superficial reflux (OR = 0.71, 95% CI : 0.50-1.01). In age-adjusted analyses in men, height was related to reflux, (OR = 1.13, 95% CI : 1.02-1.26) and straining at stool was related to superficial reflux (OR = 1.94, 95% CI : 1.12-3.35). No associations were found in either sex between reflux and social class, lifetime cigarette consumption, dietary fibre intake and intestinal transit time.

CONCLUSIONS

This population study did not identify strong and consistent lifestyle risk factors for venous reflux although previous pregnancy, lower use of oral contraceptives, obesity and mobility at work in women and height and straining at stool in men may be implicated.

Differential splicing of transcripts encoding the orphanin FQ/nociceptin precursor

Orphanin FQ or nociceptin (OFQ/N), the heptadecapeptide agonist for the NOP receptor, is derived by proteolytic processing from a precursor protein, preproOFQ/N. Previous studies have reported alternative splicing between exons 3 and 4 of the mouse OFQ/N transcript, which, upon translation, would yield precursor proteins with different C-termini. Using RT-PCR, we identified similar alternative splicing of preproOFQ/N transcripts in humans and rats. In addition, we identified two novel human preproOFQ/N splice variants from which exon 2 has been excised and which also undergo alternative splicing between exons 3 and 4. Exon 2 contains the translational start site for preproOFQ/N and encodes the signal peptide sequence. In vitro translation of cRNAs lacking exon 2 yields shorter translation products which arise from an alternative initiator methionine located within exon 3. The resulting proteins would lack a signal peptide sequence, which would likely alter their cellular trafficking and processing.

Fiber intake, constipation, and risk of varicose veins in the general population: Edinburgh Vein Study

The purpose of the present study was to determine the relationship between fiber intake, constipation, and clinical venous disease in the general population. The Edinburgh Vein Study was comprised of 1566 men and women aged 18-64 years who were selected at random from the age-sex registers of 12 general practices. Fiber intake, intestinal transit time, defecation frequency and the prevalence of straining at stool were all found to be significantly different between the sexes. Men who reported that they strained to start passing a motion showed a higher prevalence of mild and severe trunk varices compared to men who did not strain. After adjustment for social class, BMI and mobility at work, this group of men showed a significantly elevated risk of having severe trunk varices (OR 2.76, 95% CI 1.16, 6.58). In contrast, no consistent relationships were seen among women. Overall, within this Western general population, an association between dietary fiber, constipation and the presence or severity of varicose veins was not supported.

Expression of MsLEC1- and MsLEC2-antisense genes in alfalfa plant lines causes severe embryogenic, developmental and reproductive abnormalities

Although it has been proposed that plant lectins play a number of roles, the function of these proteins in normal plant growth and development has been unclear. To analyze the functions of putative alfalfa lectin genes, lines of transgenic alfalfa plants expressing approximately half of the open reading frame of MsLEC1 or MsLEC2, in the antisense or sense orientation, were established and analyzed. The antisense plants displayed severe abnormalities in embryogenesis, and both vegetative and reproductive development were perturbed. Some differences were observed between MsLEC1- and MsLEC2-antisense plants, and abnormalities were especially severe during the early stages of development in both the primary and secondary transgenic generations. In contrast, vector-control and sense-transgene plants exhibited normal growth and development. MsLEC1 and MsLEC2 mRNA accumulation levels were reduced in cognate antisense plants, especially during the later stages of embryogenesis, but also tended to be low in MsLEC1 sense-transgene plants. However, correlated with the phenotypic abnormalities observed in the MsLEC1-antisense plants was the specific reduction in the accumulation of a candidate MsLEC1 protein. Our results suggest that the MsLEC1 and MsLEC2 gene products, in addition to being important for embryogenesis, are required throughout alfalfa development.

Neurotrophin dependence domain: a domain required for the mediation of apoptosis by the p75 neurotrophin receptor

The mechanisms underlying neurotrophin dependence, and cellular dependent states in general, are unknown. We show that a 29 amino acid region in the intracellular domain of the common neurotrophin receptor, p75NTR, is required for the mediation of apoptosis by p75NTR. Furthermore, contrary to results obtained with Fas, monomeric p75NTR is required for apoptosis induction, whereas multimerization inhibits the pro-apoptotic effect. Within the 29-residue domain required for apoptosis induction by p75NTR, a 14-residue region is sufficient as a peptide inducer of apoptosis. This 14-residue peptide requires the positively charged carboxyterminal residues for its effect on cell death, and these same residues are required by the full-length p75NTR. These studies define a novel type of domain that mediates neurotrophin dependence, and suggest that other cellular dependent states may be mediated by proteins displaying similar domains.

Hyperfine Structure in the Rotational Spectrum of GaF: A Comparison of Experimental and Calculated Spin-Rotation and Electric Field Gradient Tensors

The high-resolution pure rotational spectrum of GaF has been measured using a Balle-Flygare-type Fourier transform spectrometer. Improved nuclear quadrupolar coupling constants and rotational constants have been obtained along with the first reported fluorine spin-rotation constant for gallium fluoride, C(I) ((69)Ga(19)F, v = 0) = +32.0(21) kHz. Accurate spin-rotation tensors from microwave or molecular beam spectroscopy are particularly important to NMR spectroscopists and theoreticians because these data provide information about anisotropic nuclear magnetic shielding in the absence of intermolecular effects. For quadrupolar nuclei such as gallium, the quadrupolar interaction is sufficiently large that it is very difficult to characterize shielding tensors directly via NMR spectroscopy. The experimentally determined nuclear quadrupolar coupling constants and spin-rotation constants for GaF are compared with the results of a series of high-level ab initio calculations carried out at various levels of theory with a range of basis sets. Further calculations on BF and AlF, supplemented with available experimental data for InF and TlF, allow for the investigation of trends in nuclear magnetic shielding, spin-rotation, and electric field gradient tensors in the group-13 fluorides. Calculations at the MP2/6-311++G** and MP2/6-311G(2df, 2pd) levels provide the most consistently satisfactory results in comparison with the experimental data. Copyright 2000 Academic Press.