Identification of rabaptin-5, rabex-5, and GM130 as putative effectors of rab33b, a regulator of retrograde traffic between the Golgi apparatus and ER

The role of rab33b, a Golgi-specific rab protein, was investigated. Microinjection of rab33b mutants stabilised in the GTP-specific state resulted in a marked inhibition of anterograde transport within the Golgi and in the recycling of glycosyltransferases from the Golgi to the ER, respectively. A GST-rab33b fusion protein stabilised in its GTP form was found to interact by Western blotting or mass spectroscopy with Golgi protein GM130 and rabaptin-5 and rabex-5, two rab effector molecules thought to function exclusively in the endocytic pathway. A similar binding was seen to rab1 but not to rab6, both Golgi rabs. In contrast, rab5 was as expected, shown to bind rabaptin-5 and rabex-5 as well as the endosomal effector protein EEA1 but not GM130. No binding of EEA1 was seen to any of the Golgi rabs.

Value of structured clinical and scintigraphic protocols in acute pulmonary embolism

PURPOSE

To study the use of a combination of a clinical and scintigraphic protocol in relation to the final outcome diagnosis in patients with clinical suspicion of acute pulmonary embolism (PE).

MATERIAL AND METHODS

A total of 170 patients with clinical suspicion of acute PE were all examined with ECG, blood chemistry, chest X-ray, pulmonary scintigraphy and selective pulmonary arteriography. The scintigraphic and clinical probabilities of PE were estimated on visual analogue scales (VASs) by different readers unaware of each others' results. The follow-up time was 6 months. In order to establish the final diagnosis a final outcome committee was created. They analysed in retrospect all the clinical and laboratory data and established whether the patient had had PE or not.

RESULTS

The final outcome committee concluded that 53 patients had PE. When the scintigraphic and clinical probability judgements were congruent, a combined probability of 1-25% (i.e low probability) had a negative predictive value of 98%. When the combined probability was 26-75% (i.e. intermediate) half of the cases had PE. With a combined probability of 76-100% (i.e. high) the positive predictive value was 100%.

CONCLUSION

By applying a model of combined clinical and scintigraphic probabilities for PE, the diagnosis is ruled in when the combined probability is high, and ruled out when the combined probability is low. However, nearly half of the patients will still have an uncertain diagnosis for which further diagnostic procedures may be allocated.

[A controlled trial with prolonged follow up: percutaneous intervention in acute myocardial infarction is equivalent to thrombolytic therapy]

Previous studies comparing percutaneous coronary intervention (PCI) with thrombolysis for treatment of myocardial infarction with ST-elevation have in meta-analyses but not in randomized trials shown that PCI is more effective. Despite a large volume of primary PCI performed in Sweden no controlled trials have been carried out. The present study included 96 patients with myocardial infarction with ST-segment elevation treated with primary PCI 1995-1998. The main indications were shock (15 cases), contraindication to thrombolysis (24 cases), as an alternative to thrombolysis (57 cases), with a mortality in the respective groups of 67, 25 and 10 percent. Controls matched for age and infarct location and treated with thrombolysis could be identified for 55 of the patients treated with PCI. After four years 40 percent and 52 percent of the patients treated with PCI and thrombolysis respectively reached the combined endpoint of death/myocardial infarction/revascularization/angina pectoris (not significant). In conclusion, the study shows that primary PCI in patients with myocardial infarction with ST-segment elevation can be performed safely also in Sweden.

Neutralization of pH in the Golgi apparatus causes redistribution of glycosyltransferases and changes in the O-glycosylation of mucins

Addition of the weak base ammonium chloride (NH4Cl) or the proton pump inhibitor bafilomycin A1 to cultured HeLa and LS 174T cells effectively neutralized the pH gradient of the secretory pathway. This resulted in relocalization of the three studied glycosyltransferases, N-acetylgalactosaminyltransferase 2, beta1,2 N-acetylglucosaminyltransferase I, and beta1,4 galactosyltransferase 1, normally localized to the Golgi stack, the medial/trans-Golgi and the trans-Golgi/TGN, respectively. Indirect immunofluorescence microscopy, immunoelectron microscopy, and subcellular fractionation of the tagged or native glycosyltransferases showed that NH4Cl caused a relocalization of the enzymes mainly to vesicles of endosomal type, whereas bafilomycin A1 gave mainly cell surface staining. The general morphology of the endoplasmic reticulum and Golgi apparatus was retained as judged from immunofluorescence and electron microscopy studies. When the O-glycans on the guanidinium chloride insoluble gel-forming mucins from the LS 174T cells were analyzed by gas chromatography-mass spectrometry after neutralization of the secretory pathway pH by NH4Cl over 10 days shorter O-glycans were observed. However, no decrease in the number of oligosaccharide chains was indicated. Together, the results suggest that pH is a contributing factor for proper steady-state distribution of glycosyltransferases over the Golgi apparatus and that altered pH may cause alterations in glycosylation possibly due to a relocalization of glycosyltransferases.

Resection of a giant left main stem coronary artery aneurysm

A 2 cm in diameter aneurysm of the left main stem was diagnosed in 1979. The aneurysm increased to 10 cm in diameter during 20 years. It was resected and successful bypass surgery was performed. No previous report was found of a giant true aneurysm involving the left main stem.

Promoter-proximal regulatory elements involved in oriP-EBNA1-independent and -dependent activation of the Epstein-Barr virus C promoter in B-lymphoid cell lines

The identification of the cellular factors that control the transcription regulatory activity of the Epstein-Barr virus C promoter (Cp) is fundamental to the understanding of the molecular mechanisms that control virus latent gene expression. Using transient transfection of reporter plasmids in group I phenotype B-lymphoid cells, we have previously shown that the -248 to -55 region (-248/-55 region) of Cp contains elements that are essential for oriPI-EBNA1-dependent as well as oriPI-EBNA1-independent activation of the promoter. We now establish the importance of this region by a detailed mutational analysis of reporter plasmids carrying Cp regulatory sequences together with or without oriPI. The reporter plasmids were transfected into group I phenotype Rael cells and group III phenotype cbc-Rael cells, and the Cp activity measured was correlated with the binding of candidate transcription factors in electrophoretic mobility shift assays and further assessed in cotransfection experiments. We show that the NF-Y transcription factor interacts with the previously identified CCAAT box in the -71/-63 Cp region (M. T. Puglielli, M. Woisetschlaeger, and S. H. Speck, J. Virol. 70:5758-5768, 1996). We also show that members of the C/EBP transcription factor family interact with a C/EBP consensus sequence in the -119/-112 region of Cp and that this interaction is important for promoter activity. A central finding is the identification of a GC-rich sequence in the -99/-91 Cp region that is essential for oriPI-EBNA1-independent as well as oriPI-EBNA1-dependent activity of the promoter. This region contains overlapping binding sites for Sp1 and Egr-1, and our results suggest that Sp1 is a positive and Egr-1 is a negative regulator of Cp activity. Furthermore, we demonstrate that a reporter plasmid that in addition to oriPI contains only the -111/+76 region of Cp still retains the ability to be activated by EBNA1.

Quantitative thermal perception thresholds relative to exposure to vibration

OBJECTIVES

To assess the risk of disturbed thermal perception relative to exposure to vibration, to investigate a possible exposure-response relation and to analyse a possible relation between thermal perception and sensory symptoms.

METHODS

The study was based on a cross section of 123 male workers exposed to vibration and 62 male workers who were not exposed. Thermal perception of cold, warmth, and heat pain was bilaterally determined from the thenar eminence by the method of limits. Perception of cold and warmth were also tested in the second digit. Personal energy equivalent exposure to vibration was measured for all subjects. Vibration was measured in accordance with International Standards Organisation (ISO) 5349 and assessed separately for the left and right hand.

RESULTS

Combining exposure times and intensities gave the left hand an 0.80 exposure to vibration compared with the right. The risk of having contracted reduced thermal perception was increased at all test sites. The risk was higher for the thenar measurements than the finger measurements. A yearly extra contribution of 4000 mh/s(2) in cumulative exposure increases the risk of contracting a wider neutral zone by 18% (95% confidence interval (95% CI) 1.06 to 1.32) for the right and 18% (1.05 to 1.32) for the left hand side. Subjects with symptoms of nocturnal paraesthesia had a rate ratio (95% CI) of 2.80 (1.17 to 6.67) for the right hand and 2.72 (1.12 to 6.63) for the left hand for increased neutral zones at the thenar eminence.

CONCLUSIONS

The results indicate thermal sensory impairment related to cumulative exposure to vibration. The effect appeared at vibration levels below the current guiding standard. Quantitative sensory testing of thermal perception offers the chance to assess this specific hazard to the peripheral sensorineural system associated with hand intensive work entailing vibration.

Chlorite dismutase from Ideonella dechloratans

Chlorite dismutase has been purified from the chlorate-metabolizing bacterium Ideonella dechloratans. The purified enzyme is tetrameric, with a relative molecular mass of 25,000 for the subunit, and contains about 0.6 heme/subunit as isolated. Its catalytic properties are similar, but not identical, to those found for a similar enzyme purified earlier from the bacterium GR-1. The heme group in Ideonella chlorite dismutase is readily reduced by dithionite, in contrast to the GR-1 enzyme, and redox titration gave a value of -21 mV for the midpoint potential at pH 7. The heme group has been characterized by optical and EPR spectroscopy. It is high-spin ferric at neutral pH, with spectroscopic properties similar to those found for cytochrome c peroxidase. In the alkaline pH range, a low-spin compound is formed. A 22-residue N-terminal amino acid sequence has been determined and no homologue has been found in the protein sequence databases.

A case-referent study of cancer mortality among sulfate mill workers in Sweden

OBJECTIVES

To investigate whether workers in Swedish sulfate mills have an increased risk of death from certain malignancies that have previously been linked to the pulping process.

METHODS

Subjects of the study (n=2480) were men aged 40-75 at death during 1960-89 in the parishes surrounding four sulfate mills. Exposure assessment was based on information from the personnel files in the mills- 35% of the subjects were recognised there, and work categories were created.

RESULTS

Among all sulfate mill workers, the odds ratio (OR) (90% confidence interval (90% CI)) for death from lung cancer was 1.6 (1.1 to 2.3), pleural mesotheliomas 9.5 (1.9 to 48), brain tumours 2.6 (1.2 to 5.3), and liver or biliary tract cancer 2.3 (1.0 to 5.2). There was an increased mortality from leukaemia among workers in the soda recovery plant (5.9 (2.6 to 13)) and bleaching plant and digester house (2.8 (1.0 to 7.5)).

CONCLUSIONS

Sulfate mill workers were at increased risk of dying from lung cancer and pleural mesotheliomas, probably due to exposure to asbestos. Increased risks of brain tumours and cancers of the liver or biliary tract were also found but the aetiology is not obvious.

Differences in co-variation of inorganic elements in the bulk and surface of human deciduous enamel: an induction analysis study

This paper demonstrates a method for determination of co-variation between some inorganic elements in the bulk and surface areas of human tooth enamel. The technique is based on a computerised induction analysis of data obtained by secondary ion mass spectrometry (SIMS). When comparing the present data with an earlier study from our laboratory, it became evident that with only a moderate increase in the amount of data for the induction analysis, the results increased very considerably in reliability and precision. The patterns of co-variation between different elements differed between the bulk- and surface enamel. Only Mg expressed a similar pattern. In the bulk enamel the elements Na and P expressed a high degree of co-variation. Similarly, Mg and C expressed a high degree of co-variation. Mg was an element often found to co-vary with bulk enamel elements. In the enamel surface, F and Cl co-varied. In addition, Cl was an element often found to co-vary with other enamel surface elements.

[Curative treatment of ventricular cancer]

Extended lymphadenectomy on connection with the surgical treatment of gastric cancer is gaining access in western centres especially since Japanese centres have shown an ever increasing rate of survival over several decades, coupled with the fact that operative procedures have become more sophisticated. The latest prospective studies in the west seem to confirm the value of lymphadenectomy in some patients. Furthermore, correct staging demands extended lymphadenectomy. For patients with gastric cancer, adjuvant preoperative chemotherapy is probably an asset.

The influence of curli, a MHC-I-binding bacterial surface structure, on macrophage-T cell interactions

Escherichia coli express thin surface fimbriae called curli which bind soluble matrix proteins and major histocompatibility complex (MHC)-I molecules. The present study addressed the ability of purified curli or curliated E. coli to influence peptide presentation on MHC-I, T cell proliferation and bacterial uptake by macrophages. In vitro studies with curli-proficient E. coli YMel and the isogenic curli-deficient strain YMel-1, both expressing the model antigen Crl-OVA, showed that curli expression by E. coli does not appear to influence the efficiency by which the bacteria are processed by murine macrophages for OVA(257-264) presentation on K(b). Furthermore, curli expression by E. coli did not influence the binding of exogenously added OVA(257-264) peptide to K(b) on the surface of prefixed macrophages. In addition, neither curliated nor non-curliated heat-killed bacteria influenced proliferation of either murine or human T cells stimulated with anti-CD3. Finally, curliated E. coli adhered to and were internalized by macrophages from C57BL/6 and MHC-I-deficient TAP1(-/-) mice equally well. Together these studies show that curli expression by E. coli does not appear to influence phagocytic processing of bacteria expressing Crl-OVA for OVA(257-264)/K(b) presentation, the binding of exogenously added OVA(257-264) to K(b) or T cell proliferation. In addition, although curli expression by E. coli enhances bacterial interaction with macrophages, curli interaction with MHC-I does not significantly contribute to this adherence.

Geographical differences in the incidence of acute myocardial infarction in Sweden. Analyses of possible causes using two parallel case-control studies

OBJECTIVES

To analyse differences in myocardial infarction incidence between two Swedish counties and to evaluate the importance of major risk factors for the observed differences.

DESIGN

The incidence of first myocardial infarction was studied using information from registers. For a number of risk factors of myocardial infarction, the prevalence as well as the relative risk was estimated from population controls of case-control studies in the two areas.

SUBJECTS

Men and women aged 45-64 years in Stockholm and Västernorrland County 1993-94.

MAIN OUTCOME MEASURES

Relative risks (RRs) and impact fractions were used to evaluate the importance of differences in risk factor prevalence for differences in myocardial infarction incidence between the two areas.

RESULTS

The incidence of first myocardial infarction was higher in Västernorrland than in Stockholm amongst both men (RR = 1.23; 95% CI = 1.08-1.40) and women (RR = 1.41; 95% CI = 1.11-1.79). Obesity and increased levels of blood serum lipids were more prevalent in Västernorrland than in Stockholm amongst men with impact fractions of 6 and 9-11%, respectively. Amongst women, corresponding differences were not seen, but job strain and shift work tended to be more common in the more northern area. Current smoking was more frequent in Stockholm, particularly for women.

CONCLUSIONS

The incidence of first myocardial infarction was higher in Västernorrland than in Stockholm in both genders. A higher prevalence of obesity and elevated blood serum lipids may explain, in part, this excess incidence amongst men, but amongst women the causes of the higher incidence in the more northern area remain largely unclear.

[Policy document. Catheter-based diagnosis and treatment of coronary diseases]

Diagnostic coronary angiography and percutaneous coronary interventions (PCI) are rapidly developing fields. In-house thoracic surgery backup is no longer a prerequisite for PCI. The demand for physicians trained in interventional cardiology has created a need to formalise such education. The Swedish societies of cardiology and thoracic radiology have agreed on a policy document establishing the details of this education. It is the responsibility of the tutor to decide when the pupil has achieved adequate skills.

Halo structure of (14)Be

The two-neutron halo nucleus (14)Be has been investigated in a kinematically complete measurement of the fragments ((12)Be and neutrons) produced in dissociation at 35 MeV/nucleon on C and Pb targets. Two-neutron removal cross sections, neutron angular distributions, and invariant mass spectra were measured, and the contributions from electromagnetic dissociation (EMD) were deduced. Comparison with three-body model calculations suggests that the halo wave function contains a large nu(2s(1/2))(2) admixture. The EMD invariant mass spectrum exhibited enhanced strength near threshold consistent with a nonresonant soft-dipole excitation.

Protein sorting in the Golgi apparatus: a consequence of maturation and triggered sorting

To explain how resident proteins distribute in peak-like patterns at various positions in the secretory pathway, Glick and co-workers postulated that resident proteins comprise different populations (termed kin populations) and that these compete with each other for entering retrograde transport carriers [Glick et al. (1997) FEBS Lett. 414, 177-181]. Using modelling and computer simulation, they could demonstrate that differences in competitiveness sufficed to generate overlapping but distinct peak-like steady state distributions of the different kin populations across the Golgi stack. In this study, we have tested the robustness of the competition model and find that over-expression or changes in the number of kin populations affect their overall steady state distributions. To increase the robustness of the system, we have introduced a milieu-induced trigger for recycling. This allows for a decrease in the coupling between kin populations permitting both over-expression as well as changes in the number of kin populations. We have also extended the model to include a Golgi to endoplasmic reticulum (ER) recycling pathway and find that only a small amount of resident proteins may recycle at any time without upsetting their observed distributions in the Golgi stack. The biological relevance of a trigger-induced sorting mechanism and ER recycling is discussed.

Slow-motion theory of nuclear spin relaxation in paramagnetic low-symmetry complexes: A generalization to high electron spin

The slow-motion theory of nuclear spin relaxation in paramagnetic low-symmetry complexes is generalized to comprise arbitrary values of S. We describe the effects of rhombic symmetry in the static zero-field splitting (ZFS) and allow the principal axis system of the static ZFS tensor to deviate from the molecule-fixed frame of the nuclear-electron dipole-dipole tensor. We show nuclear magnetic relaxation dispersion (NMRD) profiles for different illustrative cases, ranging from within the Redfield limit into the slow-motion regime with respect to the electron spin dynamics. We focus on S = 3/2 and compare the effects of symmetry-breaking properties on the paramagnetic relaxation enhancement (PRE) in this case with that of S = 1, which we have treated in a previous paper. We also discuss cases of S = 2, 5/2, 3, and 7/2. One of the main objectives of this investigation, together with the previous papers, is to provide a set of standard calculations using the general slow-motion theory, against which simplified models may be tested. Copyright 2000 Academic Press.

Forearm blood flow responses to neuropeptide Y, noradrenaline and adenosine 5'-triphosphate in hypertensive and normotensive subjects

Neuropeptide Y (NPY), noradrenaline (NA) and adenosine 5'-triphosphate (ATP) are important co-transmitters in the sympathetic nervous system, which has a central role in cardiovascular control. In order to evaluate if hypertension is associated with alterations in vascular responses to sympathetic co-transmitters we studied the effects of intra-arterial infusion of NPY, NA and ATP on forearm blood flow. Blood flow was measured by venous occlusion plethysmography in six hypertensive (mean arterial blood pressure (MAP) 113 +/- 4 mmHg) and six matched normotensive subjects (MAP 97 +/- 3 mmHg). NPY and NA significantly reduced forearm blood flow, while a powerful increase was seen with ATP. Forearm vascular resistance, calculated as MAP divided by forearm blood flow, was significantly increased by NPY and NA and strongly reduced by ATP. There was no difference between hypertensive and normotensive subjects in response to either transmitter. In conclusion, vascular reactivity to intra-arterial administration of NPY, NA and ATP seems to be intact in hypertensive patients without metabolic aberrations.

[Atrial septal defect--catheter-based closure now feasible!]

Atrial septal defects (ASD) of hemodynamic significance are usually treated surgically in early childhood. However, many cases will not be detected until the patient has become an adult. As there is a risk of development of pulmonary hypertension and tachyarrythmia in hemodynamically significant defects, closure is necessary. Although surgery is considered a safe procedure with very low perioperative mortality, there is a risk of complications and prolonged hospitalization, and postoperative convalescence is two months. Today we are able to offer patients with ASD of the secundum type an alternative treatment using catheter technique. The devices used are self expanding and easy to deploy, with a high success rate and low complication rate. Post-procedural convalescence is two days.

[Surgical mesh implantation in incisional hernia. A historical follow up study]

AIM OF STUDY

To describe risk factors, recurrence rates, morbidity and satisfaction in patients operated for incisional hernia with implantation of a surgical mesh.

MATERIAL AND METHODS

The records of 60 patients undergoing an incisional hernia repair using a surgical mesh in the period 1.1.1993-30.6.1998 were reviewed, and 49 living patients were examined.

RESULTS

During a mean follow-up of 27 months, patients with preoperative risk factors had more complications and recurrences. Overall recurrence rate was 14%. Ninety-six percent were satisfied with the operation and 90% wanted the same operation in case of recurrence.

CONCLUSION

Operation for incisional hernia using implantation of a surgical mesh is a safe and well tolerated procedure, care must be taken in patients with risk factors.

Sexual conflict promotes speciation in insects

Speciation rates among extant lineages of organisms vary extensively, but our understanding of the causes of this variation and, therefore, the processes of speciation is still remarkably incomplete. Both theoretical and empirical studies have indicated that sexual selection is important in speciation, but earlier discussions have focused almost exclusively on the potential role of female mate choice. Recent findings of postmating reproductive conflicts of interest between the sexes suggest a quite different route to speciation. Such conflicts may lead to perpetual antagonistic coevolution between males and females and may thus generate rapid evolutionary divergence of traits involved in reproduction. Here, we assess this hypothesis by contrasting pairs of related groups of insect species differing in the opportunity for postmating sexual conflict. Groups where females mate with many males exhibited speciation rates four times as high as in related groups where females mate only once. Our results not only highlight the general importance of postmating sexual selection in speciation, but also support the recent suggestion that sexual conflict is a key engine of speciation.

Comparison of two extraction methods independently developed on two conceptually different automated supercritical fluid extraction systems for the determination of polychlorinated biphenyls in sediments

Two extraction methods that independently have been developed on conceptually different automated supercritical fluid extraction systems, ISCO SFX 3560 (syringe pump and liquid trapping) and Hewlett-Packard 7680T SFE (reciprocating pump and solid-phase trapping), were compared for the extraction of polychlorinated biphenyls from two Swedish sediments. The results demonstrated that the high-temperature ISCO method in some cases yields a more exhaustive extraction, but also less clean extracts due to co-extraction of unwanted matrix components which are all present in the trapping solvent. The medium-temperature Hewlett-Packard method may sometimes cause problems with quantitative recoveries, but on the other hand it yields very clean extracts due to the extra selectivity resulting from collection on a solid-phase trap.

Breaking the COPI monopoly on Golgi recycling

The unexpected discovery of a transport pathway from the Golgi to the endoplasmic reticulum (ER) independent of COPI coat proteins sheds light on how Golgi resident enzymes and protein toxins gain access to the ER from as far as the trans Golgi network. This new pathway provides an explanation for how membrane is recycled to allow for an apparent concentration of anterograde cargo at distinct stages of the secretory pathway. As signal-mediated COPI-dependent recycling also involves the concentration of resident proteins into retrograde COPI vesicles, the main bulk of lipids must be recycled, possibly through a COPI-independent pathway.

The evolution of polyandry: multiple mating and female fitness in insects

Theory suggests that male fitness generally increases steadily with mating rate, while one or a few matings are sufficient for females to maximize their reproductive success. Contrary to these predictions, however, females of the majority of insects mate multiply. We performed a meta-analysis of 122 experimental studies addressing the direct effects of multiple mating on female fitness in insects. Our results clearly show that females gain directly from multiple matings in terms of increased lifetime offspring production. Despite a negative effect of remating on female longevity in species without nuptial feeding, the positive effects (increased egg production rate and fertility) more than outweigh this negative effect for moderate mating rates. The average direct net fitness gain of multiple mating was as high as 30-70%. Therefore, the evolutionary maintenance of polyandry in insects can be understood solely in terms of direct effects. However, our results also strongly support the existence of an intermediate optimal female mating rate, beyond which a further elevated mating rate is deleterious. The existence of such optima implies that sexual conflict over the mating rate should be very common in insects, and that sexually antagonistic coevolution plays a key role in the evolution of mating systems and of many reproductive traits. We discuss the origin and maintenance of nuptial feeing in the light of our findings, and suggest that elaborate and nutritional ejaculates may be the result of sexually antagonistic coevolution. Future research should aim at gaining a quantitative understanding of the evolution of female mating rates. Copyright 2000 The Association for the Study of Animal Behaviour.