Development of fatigue symptoms during simulated driving

Why do people sometimes allow themselves to be overcome by fatigue? Ancient human survival may have depended on ignoring fatigue. Its modern occurrence in the absence of strain may further render us insensitive to its warning value. To test whether deliberate monitoring of certain symptoms may help drivers and other workers realize when they need to rest to avoid hazard, the development of fatigue while driving a simulator was objectively measured in terms of how many persons quit driving as a function of time. Some subjects asked to stop after 90 minutes; others lasted 240 minutes. Grouping data from an adapted Pearson [(1957) Journal of Applied Psychology, 44, 186-191] fatigue checklist revealed a curious phenomenon. No matter how long subjects drove before wanting to quit, they still developed much the same subjective level of fatigue at the end. This suggests that people do not differ greatly in how much fatigue they can tolerate but rather how quickly they reach a certain critical level of fatigue. Averaging fatigue scores backwards from the time subjects quit produced a function similar to the quitting function. Similar treatment of the other data revealed certain clusters of symptoms whose development also paralleled the development of fatigue.

Adding a visual linear scale probability to the PIOPED probability of pulmonary embolism

PURPOSE

Reporting a lung scintigraphy diagnosis as a PIOPED categorical probability of pulmonary embolism offers the clinician a wide range of interpretation. Therefore the purpose of this study was to analyze the impact on lung scintigraphy reporting of adding a visual linear scale (VLS) probability assessment to the ordinary PIOPED categorical probability.

MATERIAL AND METHODS

The study material was a re-evaluation of lung scintigrams from a prospective study of 170 patients. All patients had been examined by lung scintigraphy and pulmonary angiography. The scintigrams were re-evaluated by 3 raters, and the probability of pulmonary embolism was estimated by the PIOPED categorization and by a VLS probability. The test was repeated after 6 months.

RESULTS

There was no significant difference (p > 0.05) in the area under the ROC curve between the PIOPED categorization and the VLS for any of the 3 raters. Analysis of agreement among raters and for repeatability demonstrated low agreement in the mid-range of probabilities.

CONCLUSION

A VLS probability estimate did not significantly improve the overall accuracy of the diagnosis compared to the categorical PIOPED probability assessment alone. From the data of our present study we cannot recommend the addition of a VLS score to the PIOPED categorization.

Presence of contractile endothelin-A and dilatory endothelin-B receptors in human cerebral arteries

OBJECTIVE

The aim of the present study was to elucidate the endothelin receptor subtypes responsible for the endothelin-induced vasomotor responses of human cerebral arteries.

METHODS

Human cerebral arteries with endothelium were mounted in in vitro tissue baths, and the vascular responses to endothelin-1 (ET-1) and sarafotoxin 6c (a selective ETB agonist) were studied in the presence or absence of endothelin blockers, bosentan (Ro 47-0203), a novel nonpeptide ETA and ETB receptor antagonist, and FR139317, a selective ETA receptor antagonist. The presence of messenger ribonucleic acid encoding the human ETA and ETB receptors in human cerebral arteries with intact endothelium and in segments denuded of endothelium was studied by the use of reverse transcriptase-polymerase chain reaction.

RESULTS

ET-1 induced concentration-dependent contraction of human cerebral arteries; the pEC50 value was 9.4 +/- 0.2. The vasoconstriction was significantly antagonized both by bosentan and by FR139317. The pA2 values were 7.2 +/- 0.4 and 7.4 +/- 0.4, respectively. Sarafotoxin 6c failed to cause contraction of human cerebral arteries. In precontracted vessels, however, sarafotoxin 6c induced dilatation that was significantly inhibited by bosentan (10 mumol/L), resulting in a pA2 value of 6.0 +/- 0.2. Furthermore, messenger ribonucleic acid encoding the human ETA and ETB receptors was detected in human cerebral arteries both with and without endothelium.

CONCLUSION

The ET-1-induced vasoconstriction of human cerebral arteries is primarily mediated by the ETA receptor, whereas the sarafotoxin 6c-induced vasodilatation seems to be mediated via the ETB receptor.

Observer agreement and accuracy for lung scintigraphy: a comparison with pulmonary angiography

This study investigated whether the moderate observer agreement rate for lung scintigraphy, when using the PIOPED criteria, reflects significant variations in accuracy. In a prospective study, 170 patients were investigated with lung scintigraphy and pulmonary angiography. The lung scintigrams were read according to the PIOPED criteria by three skilled observers from different hospitals who had no experience of consensus interpretation. The scintigrams were reinterpreted 6 months later. The inter-observer agreement rates were moderate and fair, with kappa values of 0.49 (0.44-0.54) for the first reading and 0.36 (0.31-0.41) for the second reading. The intra-observer agreement rates were good and moderate, with kappa values of 0.62 (0.51-0.73), 0.52 (0.42-0.62) and 0.54 (0.44-0.64). There were no significant differences between the observers in the areas under the ROC curves. However, one observer showed a significant difference between his first and second reading (P = 0.02). All three observers showed good accuracy. Although there were substantial variations in the inter- and intra-observer agreement rates, this was only reflected to a minor degree in the accuracy.

[Incisional hernia. A study of morbidity, mortality and bed utilization in a Danish county]

Four hundred and four patients operated for ventral hernia during a five year period were reviewed with special emphasis on morbidity, mortality and number of days in hospital. The patients were divided into 357 patients who had been operated for ventral hernia only once (A) and 47 patients who had been operated more than once for ventral hernia (B). There were no significant differences between the two groups regarding to ages or preoperative condition. The postoperative complications were 21% in group A and 12% in group B, although this was not statistically significant. Of those who suffered a complication after the operation, 76% had a competing illness prior to the operation. The overall mortality was 0.5%. The patients were hospitalized for a total of 4846 days. In view of the results of this material and of the high recurrence rate demonstrated in the literature, a restrictive attitude towards operations for ventral hernia is recommended.

A flash-photolysis study of the reactions of a caa3-type cytochrome oxidase with dioxygen and carbon monoxide

The time course of absorbance changes following flash photolysis of the fully-reduced carboxycytochrome oxidase from Bacillus PS3 in the presence of O2 has been followed at 445, 550, 605, and 830 nm, and the results have been compared with the corresponding changes in bovine cytochrome oxidase. The PS3 enzyme has a covalently bound cytochrome c subunit and the fully-reduced species therefore accommodates five electrons instead of four as in the bovine enzyme. In the bovine enzyme, following CO dissociation, four phases were observed with time constants of about 10 microseconds, 30 microseconds, 100 microseconds, and I ms at 445 nm. The initial, 10-microsecond absorbance change at 445 nm is similar in the two enzymes. The subsequent phases involving heme a and CuA are not seen in the PS3 enzyme at 445 nm, because these redox centers are re-reduced by the covalently bound cytochrome c, as indicated by absorbance changes at 550 nm. A reaction scheme consistent with the experimental observations is presented. In addition, internal electron-transfer reactions in the absence of O2 were studied following flash-induced CO dissociation from the mixed-valence enzyme. Comparisons of the CO recombination rates in the mixed-valence and fully-reduced oxidases indicate that more electrons were transferred from heme a3 to a in PS3 oxidase compared to the bovine enzyme.

Classification of species in the genus Penicillium by Curie point pyrolysis/mass spectrometry followed by multivariate analysis and artificial neural networks

Curie point pyrolysis/mass spectrometry of Penicillium species was performed with 530 degrees C Curie point foils. The mass spectra were submitted to principal component analysis, canonical variates analysis and hierarchical cluster analysis, producing a final dendrogram by the use of average linkage clustering. By this approach a successful classification of the species Penicillium italicum, P. expansum and P. digitatum originating from fruits was obtained. Isolates of the same species grouped together in the dendrogram, while the different species were distinguished. Also when grown on two different agar media, replicates of the same species grouped together. Likewise, a satisfactory classification was achieved by multivariate analysis of the data for various isolates of the cheese-associated fungi Aspergillus versicolor, P. discolor, P. roqueforti, P. solitum, P. verrucosum, P. commune and P. palitans. However, some difficulties appeared in distinguishing the closely related species P. commune and P. palitans. Such difficulties became greater on including more isolates and limiting the analysis to five of the species. The use of back-propagation artificial neural networks, in contrast, resulted in a correct classification in all cases. Thus, it is concluded that Curie point pyrolysis/mass spectrometry is useful in chemotaxonomic studies of the closely related species in the genus Penicillium.

Contractile effects of neuropeptide Y in human subcutaneous resistance arteries are mediated by Y1 receptors

The aim of our study was to determine the neuropeptide Y (NPY) receptor subtype responsible for the NPY-induced contraction of human subcutaneous (s.c.) resistance arteries. To elucidate this, we used (a) in vitro studies of NPY agonists: NPY, peptide YY (PYY), and Pro34NPY induced equally strong and equipotent concentration-dependent contractions of human s.c. resistance arteries, whereas NPY13-36 and NPY18-36 had no contractile effects; (b) in vitro studies using the NPY Y1-receptor antagonist, BIBP3226, which in nanomolar concentrations inhibited the contractile effect of NPY, causing a rightward shift of the concentration-response curve. pEC50 for NPY alone, 8.41 +/- 0.21; NPY + BIBP3226, 10 nM, 7.79 +/- 0.21; NPY + BIBP3226, 100 nM, 7.18 +/- 0.18; NPY + BIBP3226, 1 microM, 6.32 +/- 0.05 (n = 5-8). Schild-plot analysis indicated competitive antagonism: pA2 = 8.53 +/- 0.22 and slope = 0.99 +/- 0.14; (c) with reverse transcriptase-polymerase chain reaction (RT-PCR), we detected messenger RNA (mRNA) encoding the human NPY Y1 receptor and a splice variant of the receptor in human s.c. resistance arteries. On the basis of the agonists' potency order, the antagonistic effect of BIBP3226 on the NPY-induced contraction, and the presence of mRNA encoding the NPY Y1 receptor, we conclude that the NPY-induced contraction of human s.c. resistance arteries is mediated by NPY Y1 receptors.

Neuropeptide Y potentiates noradrenaline-induced contraction through the neuropeptide Y Y1 receptor

To elucidate which neuropeptide Y receptor subtype is responsible for the neuropeptide Y-induced potentiation of the noradrenaline-evoked contraction in human omental arteries we used antisense oligodeoxynucleotide (Antisense), the new selective neuropeptide Y Y1 receptor antagonist, BIBP3226 {(R)-N2-(diphenylacetyl)-N-[(4-hydroxyphenyl) methyl]-D-arginine-amide} and the reverse transcriptase-polymerase chain reaction (RT-PCR). Neuropeptide Y significantly potentiated the noradrenaline-induced contraction in non-incubated vessels (pEC50 6.4 +/- 0.2 vs. 5.9 +/- 0.2) and in vessels incubated with 1 microM Sense oligodeoxynucleotide (Sense) (pEC50 6.0 +/- 0.1 vs. 5.6 +/- 0.2). In vessels incubated with 1 microM Antisense the potentiating effect of neuropeptide Y was completely abolished. BIBP3226 (1 microM) inhibited the neuropeptide Y-induced potentiation in human omental arteries (pEC50 5.8 +/- 0.3 vs. 6.4 +/- 0.2). Finally, messenger RNA for the neuropeptide Y Y1 receptor was detected using RT-PCR. On the basis of our results we conclude that the neuropeptide Y-induced potentiation of the noradrenaline-induced contraction is mediated by the neuropeptide Y Y1 receptor.

A computerized induction analysis of possible co-variations among different elements in human tooth enamel

In recent decades software tools in the area of artificial intelligence have rapidly developed for use in personal computers. Interactive rule induction utilizing mathematical algorithms has become a powerful tool in data analysis and in making rules and patterns explicit. Data from a Secondary Ion Mass Spectrometry (SIMS) elemental analysis of human dental enamel were used to elucidate co-variations between certain elements. A co-variation analysis was performed employing a computerized induction analysis program, as well as a neural network program. Both analyses, confirming each other, revealed co-variations between certain elements in dental enamel in addition to exclusion of data of no importance for chosen outcomes. The results are presented in hierarchic diagrams, in which the importance for every specific element is given by its position and level in the diagram (decision tree). From the results it became evident that elements such as chlorine and sodium expressed a high co-variation level. Similarly fluorine and potassium co-varied, as well as magnesium and the trace element strontium. It was demonstrated that data from an elemental analysis could be processed by an induction analysis to reveal co-variations between certain elements in tooth enamel. The biological significance of these data is not fully understood, and further analyses in the field are needed.

Kinetics of electron and proton transfer during the reaction of wild type and helix VI mutants of cytochrome bo3 with oxygen

Site-directed mutagenesis was used to investigate the mechanism of electron and proton transfer in the ubiquinol oxidase, cytochrome bo3, from Escherichia coli. The reaction between the fully reduced form of the enzyme and dioxygen was studied using the flow--flash method. After rapid mixing of CO-bound enzyme with an O2-containing solution, CO was photodissociated, and the subsequent electron- and proton-transfer reactions were measured spectrophotometrically, the latter using a pH-indicator dye. In the wild-type, pure bo3 enzyme, without bound quinones, we observed a single kinetic phase with a rate constant of about 2.4 x 10(4) s-1, associated with formation of the ferry1 oxygen intermediate, followed by proton uptake from solution with a rate constant of about 1.2 x 10(4) s-1. Enzyme in which heme o instead of heme b was incorporated into the low-spin site displayed a slower ferry1 formation with a rate constant of about 3.6 x 10(3) s-1. Upon replacement of the acidic residue glutamate 286 in helix VI of subunit I with a nonprotonatable residue, electron transfer was slightly accelerated, and proton uptake was impaired. Mutations of other residues in the vicinity of E286 also resulted in a dramatic decrease of proton uptake, suggesting that the environment of this residue is important for efficient proton transfer. In the closely related cytochrome aa3 from P. denitrificans, the corresponding residue (E278) has been suggested to be part of a proton-transfer pathway [Iwata, S., Ostermeier, C., Ludwig, B., & Michel, H. (1995) Nature 376, 660-669]. The results are discussed in terms of a model for electron-proton coupling during dioxygen reduction.

The role of the membrane-spanning domain and stalk region of N-acetylglucosaminyltransferase I in retention, kin recognition and structural maintenance of the Golgi apparatus in HeLa cells

Using a series of chimeric and truncated N-acetylglucosaminyltransferase I (NAGT I) molecules we have shown that part of the lumenal stalk region is both necessary and sufficient for kin recognition of mannosidase II and retention in the Golgi stack. The membrane-spanning domain was not required for retention, but replacing part or all of this domain with leucine residues did have a dramatic effect on Golgi morphology. In stable cell lines, stacked cisternae were replaced by tubulo-vesicular clusters containing the mutated NAGT I. The loss of stacked cisternae was proportional to the number of leucines used to replace the membrane-spanning domain.

B cell-specific activation of the Epstein-Barr virus-encoded C promoter compared with the wide-range activation of the W promoter

We have studied the activity of reporter plasmids, carrying the Epstein-Barr virus (EBV) nuclear antigen (EBNA) promoters Wp and Cp, in a group of somatic cell hybrids obtained by fusing EBV-positive lymphoblastoid cell lines or group II/III Burkitt's lymphoma cell lines with non-B cell lines. In B/non-B cell hybrids of this type, B cell markers are extinguished as a rule, in parallel with the inactivation of Cp or Wp and down-regulation of EBNA-2-6 expression. A Wp-carrying reporter construct was active in non-B cell lines. Only cells with a B cell phenotype could support the activity of Cp-carrying plasmids. EBNA-2 transactivated Cp only in B cells. Our data suggest that while Wp can be used for EBNA transcription in B and non-B cells, Cp activity is restricted to B cells. The inability of EBNA-2 to transactivate Cp in non-B cells indicates that other factors present in B cells might be involved in Cp transactivation.

Vibrotactile perception thresholds as determined by two different devices in a working population

OBJECTIVES

The purpose of this study was to investigate whether two devices for measuring vibrotactile perception thresholds produced similar results on an individual basis and to compare the thresholds in the presence or absence of sensorineural hand symptoms and vibration exposure.

METHODS

Vibrotactile perception thresholds were measured with a vibrameter and a tactilometer in 178 men. The tactilometer uses seven discrete frequencies from 8 to 500 Hz, and the vibrameter uses one frequency (100 Hz). Agreement was assessed from the correlations and from a comparison of subjects who had thresholds above the upper quartile of each device as to the presence of sensorineural hand symptoms and occupational vibration exposure.

RESULTS

The correlation between the vibrameter and the tactilometer (125 Hz) was 0.59. The agreement between the vibrameter and the tactilometer (63 Hz), when the upper quartile was used as a limit, had a sensitivity of 0.56 and a specificity of 0.85. The sensitivity and specificity for the agreement with symptoms were 0.44 and 0.79, respectively, for the tactilometer and 0.40 and 0.78, respectively, for the vibrameter. The indices combined from the different frequencies of the tactilometer did not improve the agreement.

CONCLUSIONS

Some of the discrepancy between the measurement of the vibrameter and tactilometer can be explained by differences in the equipment, the measurement procedures, and the examiner, combined with high inter-and intraindividual variability. Neither of the two devices was superior when the results were compared as to the occurrence of hand symptoms and vibration exposure. As evaluated in this study vibrotactile perception threshold has a restricted value for screening and diagnostic purposes on an individual basis.

Sumatriptan-induced cerebral vasoconstriction as treatment of experimental intracranial hypertension

BACKGROUND

Increased intracranial pressure (ICP) is a major cause of mortality in severe head injuries and pharmacologically induced cerebral vasoconstriction has been suggested as a possible treatment. In the present study a porcine model of increased ICP was utilized to study the changes in cerebral haemodynamics and energy metabolism induced by a selective 5-hydroxytryptamine1 agonist (sumatriptan).

METHODS

ICP was raised by inflation of two balloons covering both parieto-occipital regions extradurally. The animals were randomized into four groups receiving sumatriptan. 0.01 mg.kg-1 (A), 0.03 mg.kg-1 (B), 0.1 mg.kg-1 (C), and 0.5 mg.kg-1 (D) intravenously over 10 min. Measurements of cerebral blood flow (CBF), arterio-venous oxygen content difference (CavO2), and jugular venous pH (vpH) were performed 5, 20, 40, 60, and 75 min after start of the infusion. ICP, mean arterial pressure, and EEG were recorded continuously. Direct effects of sumatriptan were also compared in cortical arteries and veins in vitro.

RESULTS

Significant decreases in ICP were obtained in groups A, B, and C while group D exhibited a progressive increase in ICP. Significant reductions in CBF, increase in CavO2, and slowing of EEG were observed in groups B, C, and D. Sumatriptan caused moderate constriction of the arteries and a more pronounced dilatation of veins in vitro.

CONCLUSION

The results indicate that a low dose of sumatriptan has the potential to reduce a raised ICP. High doses of sumatriptan cause a further increase of ICP possibly by dilatation of intracerebral veins.

Characterization of neuropeptide Y receptors mediating contraction, potentiation and inhibition of relaxation

In addition to its direct vasoconstrictive effect, neuropeptide Y (NPY) potentiates noradrenaline-(NA) induced contraction and inhibits acetylcholine-(ACh) induced relaxation: The aim of the present study was to elucidate the NPY receptor subtypes responsible for mediating these three responses. NPY, peptide YY (PYY) and pro34NPY (a NPY Y1 receptor agonist) induced equipotent and equally strong concentration-dependent contractions of guinea pig basilar arteries. NPY13-36 (a NPY Y2 receptor agonist), however, caused only weak contraction with significantly lower potency. The NPY-induced contraction was significantly inhibited by the selective NPY Y1 receptor antagonist BIBP3226 (1 microM). NPY, PYY and pro34NPY but not NPY13-36 significantly potentiated the NA-induced contraction in guinea pig mesenteric arteries. The potentiation was significantly inhibited by BIBP3226 (1 microM). In precontracted guinea pig basilar arteries, ACh induced a concentration-dependent relaxation which was significantly inhibited by NPY, PYY and NPY13-36 but not by pro34NPY. BIBP3226 had no significant effect on the NPY-induced inhibition of the relaxation. These results suggests that the NPY Y1 receptors mediate the direct contraction and the potentiation of the NA-induced contraction but not the inhibition of the ACh-induced relaxation. This effect seems to be mediated by another NPY receptor subtype, presumably by the Y2 receptor, as judged from the agonist potency order.

Primate homologues of rat TGN38: primary structure, expression and functional implications

cDNAs encoding the human and macaque homologues of rat TGN38 have been cloned and sequenced. The proteins have a highly conserved N terminus (comprising the signal peptide) and C terminus (comprising part of the lumenal domain, the membrane spanning region and cytoplasmic tail) but vary in the other part of the lumenal domain, which contains the repeat region. Whereas rat TGN38 contains 6 tandem repeats of an 8mer, both primate proteins possess 14 tandem repeats of a 14mer sequence. The human protein, like rat TGN38, is localised primarily to the TGN but is present on the cell surface and returns via endosomes. This behaviour is consistent with conservation of the membrane spanning region and the cytoplasmic tail, which contain the retention and retrieval signals, respectively, for localisation in the TGN. The unexpected differences in the lumenal domain can best be rationalised by the fact that both types of repeat domains have most of the properties of mucins. We suggest that TGN38 homologues are mucin-like molecules that regulate membrane traffic to and from the TGN.

Temporal patterns of changes in ATP/ADP ratio, glucose 6-phosphate and cytoplasmic free Ca2+ in glucose-stimulated pancreatic beta-cells

Closure of ATP-sensitive K+ (K(ATP)) channels is part of the stimulus-secretion coupling mechanism in the pancreatic beta-cell, leading to membrane depolarization and influx of Ca2+ through voltage-sensitive L-type Ca2+ channels. The elevated ATP/ADP ratio seen in the presence of high levels of glucose has been postulated to mediate the glucose-induced closure of the K(ATP) channels and rise in cytoplasmic free Ca2+ concentration ([Ca2+]i), or alternatively to be a consequence of activation of mitochondrial dehydrogenases by the increase in [Ca2+]i. To distinguish between these two possibilities, the time course of the change in the ATP/ADP ratio was determined in comparison with that of [Ca2+]i. We here show that a severalfold rise in the ATP/ADP ratio occurs rapidly on stimulation of suspensions of mouse pancreatic beta-cells with glucose. The change in the ATP/ADP ratio is an early event that begins within 20-40 s and precedes the rise in [Ca2+]i. The temporal relationship indicates that the adenine nucleotide changes cannot be a consequence of the [Ca2+]i changes and may indeed be the connecting link between glucose metabolism and [Ca2+]i changes. When the cells were sequentially treated with high glucose concentration, clonidine and finally high extracellular Ca2+ concentration to induce synchronized oscillations in [Ca2+]i in the cell suspension, corresponding oscillations in the ATP/ADP ratio were observed. Glucose 6-phosphate levels oscillated out of phase with the ATP/ADP ratio. These results support the hypothesis that the Ca2+ oscillations previously observed in glucose-stimulated single islets or beta-cells may reflect oscillations in the ATP/ADP ratio that accompany oscillatory glycolysis.

Presence of neuropeptide Y Y1 receptor mediating vasoconstriction in human cerebral arteries

The neuropeptide Y-induced vasoconstriction of human cerebral arteries is mediated by the neuropeptide Y Y1 receptor. We conclude this on the basis of our results from: (1) in vitro studies on neuropeptide Y agonists. Neuropeptide Y and pro34NPY caused potent and long-lasting contractions of human cerebral arteries, while NPY 13-36 had no contractile effect at all on the vessels tested; (2) in vitro studies using the selective Y1 receptor antagonist BIBP3226 which in increasing concentrations (10(-9)-10(-6)M) caused a parallel shift to the right of the neuropeptide Y concentration-response curve without change of the maximum contractile response (pA2 value 8.38 +/- 0.10); and (3) with reverse transcriptase-polymerase chain reaction (RT-PCR) we detected specific mRNA for a neuropeptide Y Y1 receptor in human pial and human middle cerebral arteries using three forward primers and one reverse primer.

Comparison of different methods for vibration measurements on hand-held vibrating tools

Vibration measurements have been done on hand-held tools in a group of 48 platers by evaluating the individual vibration acceleration and absorption of vibration energy. The measurement of acceleration has been done frequency-weighted and frequency-unweighted in accordance with ISO 5349 and NIOSH (USA) recommendations for hand-arm vibration standards, respectively. The acceleration and the energy absorption have been measured simultaneously in the three orthogonal directions, the latter by using a specially designed adapter. The exposure time has been determined by both subjective rating and objective measurements. Individual energy-equivalent accelerations and vibration dosages have been calculated from these data. The outcome shows that the type of tool was critical to vibration load when the different measures for determining vibration levels were used. Of the methods used, the evaluation specified by ISO 5349 makes most consideration of low frequencies of vibration (< 50 Hz), absorption of vibration energy middle frequencies (50-200 Hz) and NIOSH of high frequencies (> 200 Hz). The results show a poor correlation between the three methods used. Close agreement between mean subjective rating and objective measurement of the average exposure time was found. Further studies of the relation between results presented here and generated disturbance will be conducted, which may clarify any exposure-response relationship.

Characterization of a cis-Golgi matrix protein, GM130

Antisera raised to a detergent- and salt-resistant matrix fraction from rat liver Golgi stacks were used to screen an expression library from rat liver cDNA. A full-length clone was obtained encoding a protein of 130 kD (termed GM130), the COOH-terminal domain of which was highly homologous to a Golgi human auto-antigen, golgin-95 (Fritzler et al., 1993). Biochemical data showed that GM130 is a peripheral cytoplasmic protein that is tightly bound to Golgi membranes and part of a larger oligomeric complex. Predictions from the protein sequence suggest that GM130 is an extended rod-like protein with coiled-coil domains. Immunofluorescence microscopy showed partial overlap with medial- and trans-Golgi markers but almost complete overlap with the cis-Golgi network (CGN) marker, syntaxin5. Immunoelectron microscopy confirmed this location showing that most of the GM130 was located in the CGN and in one or two cisternae on the cis-side of the Golgi stack. GM130 was not re-distributed to the ER in the presence of brefeldin A but maintained its overlap with syntaxin5 and a partial overlap with the ER-Golgi intermediate compartment marker, p53. Together these results suggest that GM130 is part of a cis-Golgi matrix and has a role in maintaining cis-Golgi structure.