Transesophageal echocardiographic assessment of left ventricular function during apnea testing for brain death

The effects of apnea testing-induced respiratory acidosis on left ventricular function (LVF) are still controversial. The aim of the study was to assess LVF during apnea testing using transesophageal echocardiography (TEE). Twenty consecutive patients suspected of brain death, hemodynamically stable, and considered as potential organ donors were prospectively studied. A 20-min apnea test was performed after obtaining a PaCO2 > 35 mmHg and 20 min of FIO2 1 ventilation. LVF was assessed using TEE with a CFM 750 (Diasonic) connected to a 5 MHz probe. Heart rate (HR), mean arterial pressure (MAP), left ventricle end-diastolic and systolic area (LVEDA, LVESA), and LVF assessed by fractional area changes (FAC), systolic wall motion (SWM) scores, and blood gases were recorded at baseline, and after 5, 10, 15, and 20 min of apnea testing. In 19 patients, no spontaneous respiratory movement occurred during the standard 20-min period. In one patient (No. 15), the apnea test had to be stopped after 10 min because of hypoxia. HR, LVEDA, LVESA, and SWM were not significantly modified during the study. There was a progressive statistically significant decrease in MAP during apnea (from 77 +/- 10 to 63 +/- 11 mmHg), associated with a statistically significant increase in FAC at 20 min (from 48 +/- 13 to 56 +/- 8%). PaCO2 progressively rose (from 40 +/- 3 to 95 +/- 11 mmHg), associated with a decrease in pH (from 7.42 +/- 0.06 to 7.09 +/- 0.08). At the same time, PaO2 decreased slightly in all patients, but values remained well above hypoxic levels, except for one patient. Despite severe respiratory acidosis the increase in FAC suggests that apnea testing is well tolerated for brain death assessment.

Brain neurons and glial cells express Neu differentiation factor/heregulin: a survival factor for astrocytes

Neu differentiation factor (NDF, also called heregulin) was isolated from mesenchymal cells on the basis of its ability to elevate phosphorylation of ErbB proteins. Earlier in situ hybridization analysis showed that NDF was transcribed predominantly in the central nervous system during embryonic development. To gain insights into the role of NDF in brain we analyzed its distribution by immunohistochemistry and in situ hybridization. Late-gestation (day 17) rat embryos displayed high NDF immunoreactivity in both motor (e.g., putamen) and limbic (e.g., septum) regions. Lower levels of the factor were exhibited by adult brain, except for the cerebellum, where NDF expression was increased postnatally. Both neurons and glial cells were identified by immunohistochemistry as NDF-producing cells (e.g., pyramidal neurons in the cerebral cortex and glial cells in the corpus callosum). By establishment of primary cultures of rat brain cells we confirmed that NDF was expressed in neurons as well as in astrocytes. In addition, by using such primary cultures we observed that NDF treatment exerted only a limited mitogenic effect, which was accompanied by significant acceleration of astrocyte maturation. Furthermore, long-term incubation with the factor specifically protected astrocytes from apoptosis, implying that NDF functions in brain as a survival and maturation factor for astrocytes.

Purification and characterization of the Ca2+/calmodulin-dependent protein kinase II from chicken forebrain

CaM kinase II is known to be enriched in mammalian and avian brains. To determine the holoenzymic composition and functional characteristics of this kinase, a new approach for isolation was applied to isolate it from the chicken forebrain. Forebrains of hatched 45-d chicken were dissected, homogenized, and centrifuged. The supernatant was loaded onto a CaM-agarose affinity column and the calmodulin-binding proteins were eluted with EGTA. Selected eluates were loaded onto the antibody-agarose affinity column, which was prepared with monoclonal antibody (MAb) (6G9) to the CaM kinase II alpha subunit. Samples were subjected to SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and either silver-stained or blotted onto a nitrocellulose membrane. The protein composition and the immunoreactivity of the antibody-agarose affinity eluate fractions were analyzed with a densitometric scanner. Silver staining of gels showed that the beta subunit doublet, the beta' subunit, and a putative substrate were coeluted with the alpha subunit from the antibody affinity column although only the alpha subunit bound the 6G9 antibody. Scintillation counting showed that the autophosphorylation of the kinase was significantly reduced in the eluate from the antibody affinity column. Whereas silver staining indicated an increase in the relative amount of alpha subunit had occurred during purification, phosphorylation assays indicated an increase in the relative amount of the alpha subunit after the last purification step. A possible reason for this is discussed. The presence of beta/beta' subunits in the antibody-agarose affinity eluate indicated the existence of an alpha beta/beta' heteropolymer. The phosphorylation assay was not a good indication of the amount of purification because of the loss of enzyme activity following purification. In contrast, the immunoassay indicated a 97-fold purification from the cytosolic fraction was achieved using the method. In conclusion, the data indicate the existence of the CaM kinase II alpha beta/beta' heteropolymer in the chicken forebrain.

NDF/heregulin stimulates the phosphorylation of Her3/erbB3

Her3/erbB3 has been identified as a third member of the epidermal growth factor receptor (EGFR) family [(1989) Proc. Natl. Acad. Sci. USA 86, 9193-9197; (1990) Proc. Natl. Acad. Sci. USA 87, 4905-4909]. The natural ligand for Her3 has not been identified. Although recently NDF has been proposed as a specific ligand for Her4 [(1993) Nature 366, 473-475; (1993) J. Biol. Chem. 268, 18407-18410], we report here that Her3 was phosphorylated on tyrosine not only in three breast carcinoma cell lines, MDAMB453, MDAMB468 and SKBR3, but also in Her3-transfected CHO cells in response to NDF stimulation. In further studies, cells were reacted with 125I-labeled NDF and then chemically crosslinked. Immunoprecipitation with anti-Her3 revealed a dense high Mw band, greater than 400 kDa. The results suggest that NDF may be a ligand of Her3 and induces receptor hetero-oligomerization.

Measurement of the attenuation coefficient for Livermore Thoracic Phantom lungs fabricated using contemporary materials

The University of Cincinnati has reproduced the original formulation for the Livermore Thoracic Phantom lungs using contemporary materials and has adopted the linear attenuation coefficient as the primary quality assurance parameter for evaluating the performance capabilities of these new lung phantoms. The Livermore Thoracic Phantom was originally fabricated in 1978 to intercalibrate detector systems used to measure plutonium and other low-energy, photon emitting radionuclides deposited in the respiratory tract. The linear attenuation coefficient is a critical performance indicator for these phantom lungs since the presence of any material with a high effective atomic number (where Z > or = 20) will make a significant change in the photoelectric cross section, the predominant mode of interaction for plutonium x rays. A set of test lungs was fabricated with KCl to introduce a known quantity of 40K in the phantom and to determine, by measurement and calculations, what change would be made to the attenuation coefficient at photon energies below 100 keV as a result of the modified formulation. The KCl increased the linear attenuation coefficient below 60 keV by more than a factor of two, which would produce a substantial systematic error in any subsequent calibration measurements performed with these modified phantom lungs. These results support use of the attenuation coefficient as an important performance indicator for the Livermore Thoracic Phantom lungs and also suggest that KCl not be added to the lung tissue substitute formulation as a means to incorporate 40K in the phantom for low energy calibrations.

Properties of variant forms of human stem cell factor recombinantly expressed in Escherichia coli

The gene for human stem cell factor (SCF) encodes a leader sequence followed by 248 amino acids (Martin et al., 1990, Cell 63, 203). Of these 248 amino acids, the first 189 correspond to an extracellular domain and the remainder correspond to a hydrophobic transmembrane domain plus a cytoplasmic domain. A naturally occurring soluble form, released by proteolytic cleavage after amino acid 165, has been described. An alternatively spliced mRNA, lacking the codons for exon 6, has also been described. Since the amino acids encoded by exon 6 include the proteolytic cleavage site, the form expressed from the alternatively spliced mRNA tends to remain membrane-bound. In the present study, we have begun to explore structure/function relationships within the extracellular domain of SCF. Forms beginning at amino acid 1 (after the leader sequence) and ranging from 127 to 189 at the C-terminus have been recombinantly expressed in Escherichia coli and purified. In addition, forms missing the amino acids encoded by exon 6, forms missing up to 10 amino acids from the N-terminus, and forms with disulfide bond alterations have been expressed and purified. The forms have been characterized structurally, as well as functionally, in quantitative cell proliferation and receptor-binding assays. The results indicate that amino acids 1-141 comprise a structural and functional core and allow conclusions about the necessity of each of the two disulfide bonds for structure and function.

Additive effect on gas exchange of inhaled nitric oxide and intravenous almitrine bismesylate in the adult respiratory distress syndrome

OBJECTIVE

To assess the additive effect of inhaled nitric oxide (NO) and intravenous almitrine bismesylate (ALM) on gas exchange.

DESIGN

Prospective self-controlled study.

SETTING

3 medico-surgical intensive care units.

PATIENTS

17 patients with severe hypoxemia (PaO2/FIO2 ratio: 88 +/- 30 mmHg, venous admixture: 47 +/- 7%) and elevated mean pulmonary artery pressure (MPAP: 30 +/- 5 mmHg) due to adult respiratory distress syndrome (ARDS).

INTERVENTIONS

5 conditions were studied: 1) baseline, 2) 5 to 10 ppm of NO during 30 min, 3) discontinuation of NO during 30 min, 4) ALM infusion (0.5 mg/kg) during 30 min, 5) ALM infusion (0.5 mg/kg) during 30 min in combination with 5 to 10 ppm of NO.

MEASUREMENT AND RESULTS

The PaO2/FIO2 ratio rose from 88 +/- 30 to 98 +/- 37 mmHg (NS) with NO alone, and from 92 +/- 25 to 130 +/- 56 mmHg (p < 0.01) with NO + ALM (p < 0.05 vs NO alone). Seven patients were considered as "NO-responders" (rise in PaO2/FIO2 ratio of 10 mmHg or more with NO); in this subgroup the PaO2/FIO2 ratio rose from 87 +/- 30 to 128 +/- 39 mmHg (p < 0.05) with NO alone, and from 93 +/- 20 to 169 +/- 51 mmHg (p < 0.01) with NO + ALM (p < 0.05 versus NO alone). MPAP decreased from 30 +/- 5 to 26 +/- 5 mmHg (p < 0.01) with NO alone, increased slightly from 28 +/- 5 to 31 +/- 5 mmHg (NS) with ALM alone and decreased to 27 +/- 5 mmHg (p < 0.05) with NO + ALM.

CONCLUSIONS

NO + ALM had additive effects on gas exchange while decreasing MPAP in patients with ARDS. The effects of NO alone were small and non significant, except in a subgroup of 7 patients in whom the combination of both therapies had the more pronounced results.

Childhood and adolescent passive smoking and the risk of female lung cancer

BACKGROUND

Few studies have reported the relationship between passive smoking (PS) in early life and the risk of lung cancer. This study was done to evaluate the risk of female lung cancer from PS, especially that during childhood and adolescence.

METHODS

Using household exposure to tobacco smoke as an estimate of PS, a 1:1 paired case-control study was conducted in Harbin, China. We interviewed 114 female primary lung cancer cases, aged 30-69 years, and their hospital-based controls. The controls were non-cancer patients, selected from the same hospital as the cases, and matched on age (+/- 5 years), residential area and smoking status over their lifetime. There were 59 pairs who ever smoked and 55 pairs who never smoked. Information on PS was collected by residence for each of the following periods: 0-6, 7-14, 15-22, 23-30 and 31-69 years.

RESULTS

Household PS significantly increases the risk of female lung cancer for those exposed at ages 22 or younger, who have ever smoked. The risk was also increased for those non-smoking pairs when exposed under the age of 15 years. Exposure to maternal smoking at ages 14 or younger increased the risk by about 170% (odds ratio, OR 2.7, 95% confidence interval [CI]: 1.49-4.88), but not to paternal smoking (OR 1.40, 95%CI: 0.92-2.50). The risk was highest for those exposed under the age of seven (OR 3.46, 95%CI: 1.80-6.65) and was also significant at ages 7-14 (OR 3.08, 95% CI: 1.62-5.57) and 15-22 (OR 3.10, 95%CI: 1.52-6.31) years. Under the age of 23 years, the OR increased with amount of PS (P < 0.001). Of note, the OR in all five exposure periods for non-smoking pairs were similar to those for all 114 pairs studied.

CONCLUSIONS

Household PS, particularly that during childhood, increases the risk of female lung cancer. The assessment of PS should be done by different periods of exposure.

[A study of computed tomography of elderly temporomandibular joint disorders syndrome (TMJDS) patients treated with and without splint in three dimensions]

The computed tomography of elderly TMJDS patients treated with and without splint were studied in three dimensions. The results showed that the condyle was in a retruded position in the glenoid fossa in sagittal dimension and the horizontal condylar angle appeared asymmetry in axial dimension. Under the splint treatment, the retruded condyle can be adjusted to the center of the glenoid fossa and the horizontal condylar angle can be balanced, since the splint may correct the vertical dimension and eliminate the occlusal interferences. This study indicates that the horizontal condylar angle can be considered as a significant factor in diagnosis of TMJDS and evaluation of the outcome of treatment.

Structural and functional aspects of the multiplicity of Neu differentiation factors

We used molecular cloning and functional analyses to extend the family of Neu differentiation factors (NDFs) and to explore the biochemical activity of different NDF isoforms. Exhaustive cloning revealed the existence of six distinct fibroblastic pro-NDFs, whose basic transmembrane structure includes an immunoglobulin-like motif and an epidermal growth factor (EGF)-like domain. Structural variation is confined to three domains: the C-terminal portion of the EGF-like domain (isoforms alpha and beta), the adjacent juxtamembrane stretch (isoforms 1 to 4), and the variable-length cytoplasmic domain (isoforms a, b, and c). Only certain combinations of the variable domains exist, and they display partial tissue specificity in their expression: pro-NDF-alpha 2 is the predominant form in mesenchymal cells, whereas pro-NDF-beta 1 is the major neuronal isoform. Only the transmembrane isoforms were glycosylated and secreted as biologically active 44-kDa glycoproteins, implying that the transmembrane domain functions as an internal signal peptide. Extensive glycosylation precedes proteolytic cleavage of pro-NDF but has no effect on receptor binding. By contrast, the EGF-like domain fully retains receptor binding activity when expressed separately, but its beta-type C terminus displays higher affinity than alpha-type NDFs. Likewise, structural heterogeneity of the cytoplasmic tails may determine isoform-specific rate of pro-NDF processing. Taken together, these results suggest that different NDF isoforms are generated by alternative splicing and perform distinct tissue-specific functions.

Traumatic laceration of the ascending aorta detected by transesophageal echocardiography

The diagnosis of aortic injury after blunt chest trauma is of utmost importance to emergency physicians. We present a case in which transesophageal echocardiography was successful in diagnosing a transectional intimal tear on the posterior wall of the ascending aorta. Potential usefulness of transesophageal echocardiography is discussed.

Interference by complex structures of target DNA with specific PCR amplification

It has been considered that target DNA is a forgiving component for PCR amplification. Herein we present evidence to demonstrate that secondary structure located at the end of a template may interfere with the specificity of amplification. Experiments indicate that nonspecific amplification results from a long stretch of stem and loop structures at the 3' end of prochymosin cDNA. Based on the sequence of mRNA coding for prochymosin, it is argued that the sequence responsible for the formation of the complex structure described here is most likely generated during synthesis of the second cDNA strand.

[Survey of the quality of sleep during the perioperative period. Study of factors predisposing to insomnia]

In order to assess the quality of sleep in surgical patients the amount of self-rated postoperative insomnia and its predisposing factors, we conducted a three-fold questionnaire * survey in 176 consecutive patients undergoing elective orthopaedic, vascular or abdominal surgery. The first questionnaire was completed the day preceding surgery, the second at the day of discharge and the third two weeks later. This survey concerned the patient's general status, his usual sleep profile and factors which could interfere with sleep (hypnotics, pain, environmental factors) throughout the study period. It allowed quantification of these parameters and the assessment of their time-course. Perioperative insomnia appeared to be a long-lasting phenomenon which persisted after discharge. Factor analysis and multiple regression models showed that postoperative, self-rated insomnia was multifactorial and mainly explained by the amount of postoperative pain (p = 0.035).

[A study of 3 new ventilators for anesthesia: a series of tests]

We report the bench testing of three new anaesthesia ventilators: Flexima (Datex), SA2/RA2 and Cato (Dräger). The test circuit included a two compartment lung model, a pneumotachograph and a pressure gauge. Volume was integrated from flow signal. The tidal volume delivered by the Flexima and SA2/RA2 ventilators decreased with increasing mechanical work load contrarily to the Cato. Moreover, the tidal volume of the Flexima increased with the fresh gas flow. In spontaneous ventilation inspiratory resistance were low.

Improved quantitative Apt test for detecting fetal hemoglobin in bloody stools of newborns

We devised an improved spectrophotometric method, based on the differential susceptibility of various hemoglobins to alkaline denaturation, to measure the percentage of fetal hemoglobin (HbF) in bloody meconium so as to determine the source of the blood. The oxyhemoglobin of a sample was spectrophotometrically scanned from 450 to 650 nm before and after the addition of sodium hydroxide. With Allen baseline correction, the ratio of absorbance at 576 nm was linearly proportional to the percentage of HbF in the specimen as described by the equation: ratio = 0.01 (%HbF) + 0.0045 (r = 0.9971, Sy/x = 0.047). Preliminary studies on samples containing 10% or 80% HbF revealed that the method was fairly precise. The accuracy of this test was verified by comparing the results (y) with those obtained by radial immunodiffusion (x): y = 0.997x + 2.93 (r = 0.91). This preliminary study demonstrates that the modified test is simple, fast, and free from bilirubin interference. It should be useful for the diagnosis of gastrointestinal bleeding of the newborn on a stat basis.

Response of ataxia telangiectasia cells to restriction endonuclease induced DNA double-strand breaks: I. Cytogenetic characterization

Ataxia telangiectasia (AT) and normal human lymphoblastoid cell lines have been treated with either X-rays or the restriction endonucleases PvuII and BamHI using streptolysin-O poration, and the frequencies of micronuclei or chromosomal aberrations measured. We report that AT cells (AT-PA) are hypersensitive to the restriction endonucleases PvuII and BamHI, inducing DNA double-strand breaks (dsb) with either blunt or cohesive termini, respectively. Our data indicates that AT-PA cells have a dsb processing defect that leads to a higher rate of conversion of dsb into chromosomal aberrations than in normal cells. AT-PA cells showed up to a 5-fold enhanced sensitivity to PvuII over the normal (N-SW) line, a result of an increase in frequencies of chromatid aberrations. Chromosome-type aberrations appeared not to be increased in AT-PA cells over those induced in the normal N-SW line. Particularly striking was the appearance in AT-PA of high frequencies of chromatid aberrations at the 24 h sampling time. BamHI also caused enhanced aberration frequencies in AT-PA cells although the cohesive-ended dsb caused by BamHI still appeared to be less effective in causing chromosomal aberrations than the blunt-ended dsb caused by PvuII in both AT-PA and N-SW, as we have previously reported for Chinese hamster cells. The enhanced effectiveness of cohesive-ended dsb in AT-PA cells over normal cells may be a result of altered processing of dsb by AT-PA cells or may be caused by conversion of some cohesive-ended dsb into blunt-ended dsb by exonuclease digestion before ligation can take place.

Improved quantitative Apt test for detecting fetal hemoglobin in bloody stools of newborns

We devised an improved spectrophotometric method, based on the differential susceptibility of various hemoglobins to alkaline denaturation, to measure the percentage of fetal hemoglobin (HbF) in bloody meconium so as to determine the source of the blood. The oxyhemoglobin of a sample was spectrophotometrically scanned from 450 to 650 nm before and after the addition of sodium hydroxide. With Allen baseline correction, the ratio of absorbance at 576 nm was linearly proportional to the percentage of HbF in the specimen as described by the equation: ratio = 0.01 (%HbF) + 0.0045 (r = 0.9971, Sy/x = 0.047). Preliminary studies on samples containing 10% or 80% HbF revealed that the method was fairly precise. The accuracy of this test was verified by comparing the results (y) with those obtained by radial immunodiffusion (x): y = 0.997x + 2.93 (r = 0.91). This preliminary study demonstrates that the modified test is simple, fast, and free from bilirubin interference. It should be useful for the diagnosis of gastrointestinal bleeding of the newborn on a stat basis.

Phosphorylation and dephosphorylation events play critical roles in Sindbis virus maturation

We have examined the effects of various inhibitors of protein kinases and phosphatases on Sindbis virus maturation in BHK cells. 2-aminopurine, a nonspecific protein kinase inhibitor, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7), a specific inhibitor of calmodulin/Ca(2+)-dependent protein kinase, and okadaic acid (OKA), a protein phosphatase inhibitor, dose-dependently inhibited Sindbis virus maturation. Although virus production was inhibited, the membrane glycoprotein precursors PE2/E1 were exported from the endoplasmic reticulum and PE2 was converted to E2 at normal kinetic rates. The glycoproteins were delivered to the plasma membrane in conformations which rendered them competent for low pH-mediated cell-cell fusion from within. Electron microscopy showed that in the presence of W-7, virus nucleocapsids were free in the cell cytoplasm, while in the presence of OKA, the nucleocapsids were associated with cell membranes. Metabolic labeling of Sindbis virus-infected cells with [32P]orthophosphate in the presence of OKA resulted in the specific labeling of the PE2/E2 glycoprotein. We have previously shown that the carboxyl terminus of the PE2 glycoprotein is initially buried in cell membranes and is then exposed to the cytoplasm at some later stage in virus maturation. The data shown are consistent with the hypothesis that phosphorylation and dephosphorylation play a critical role in a late stage in Sindbis virus maturation, possibly in releasing of the E2 tail from cell membranes.

Comparison of cDNAs from bovine brain coding for two isoforms of calreticulin

Calreticulin is a major calcium-binding protein of the endoplasmic reticulum of non-muscle cells. In addition to a 1.9-kb calreticulin mRNA, some evidence has suggested the existence of another transcript of 3.75 kb, which is very similar to calreticulin. We report here the isolation and sequencing of cDNA clones from a bovine brain lambda gt11 cDNA library, two of which appear to code for calreticulin and a third for a novel isoform of calreticulin. The deduced amino-acid sequence of the novel clone shares high similarity with mouse calreticulin in the C-terminal 318 amino acids. However, its N-terminal sequence is completely divergent. Northern blot analysis of bovine cerebral cortex RNA indicates that the conserved region of the clone hybridizes to two messages of 1.9 kb and 3.75 kb. The divergent region of this clone hybridizes to the 3.75-kb message, but not to the 1.9-kb message. We believe that this novel clone corresponds to an alternate form of calreticulin which is identical to calreticulin toward the C-terminus, but completely different at the N-terminal region, and that this isoform is encoded by a much larger message.

Clonidine comparably decreases the thermoregulatory thresholds for vasoconstriction and shivering in humans

BACKGROUND

Clonidine stops postoperative shivering, but its underlying mechanism of action is unknown. Clonidine may impair central control of thermoregulation or act on peripheral receptors. Accordingly, the authors tested the hypothesis that clonidine reduces both the vasoconstriction and shivering thresholds, a pattern consistent with central thermoregulatory impairment.

METHODS

Seven healthy volunteers participated in the study. Thermoregulatory vasoconstriction was evaluated using forearm minus fingertip, skin-temperature gradients; values exceeding 4 degrees C were considered to be significant vasoconstriction. Systemic oxygen consumption (VO2) was measured with a canopy system. In addition, shivering was qualitatively evaluated using a simple scale, graduated from 0 (no shivering) to 2 (intense shivering). The tympanic membrane temperatures triggering significant vasoconstriction and grade 1 shivering were considered to be the thresholds for the two thermoregulatory responses. Measurements were performed after a 10-min steady state period and during cooling by central venous infusion of Ringer's lactate solution at 4 degrees C. Each subject was evaluated at two sessions, separated by at least 48 h. They were randomly and blindly assigned to received either an intravenous bolus of 75 micrograms clonidine or a placebo before cooling. When the shivering score equaled 2, 75 micrograms clonidine was injected intravenously, and repeated if necessary, to completely stop shivering.

Extraction and simultaneous elution and derivatization of 11-nor-9-carboxy-delta 9-tetrahydrocannabinol using Toxi-Lab SPEC prior to GC/MS analysis of urine

A new sample preparation procedure is described for the extraction and simultaneous elution and derivation of urine for analysis of 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THC-COOH) by gas chromatography/ion trap mass spectrometry (GC/MS). Urine samples are extracted for THC-COOH and d6-THC-COOH internal standard onto a hydrophobic membrane. Extracts are simultaneously eluted and derivatized with MSTFA while on the membrane to produce the corresponding trimethylsilane derivative. Using results of blank urine, the limits of detection and quantitation were 1.1 and 2.5 ng/mL, respectively. The linearity of the assay was 250 ng/mL. The within-run and day-to-day precision ranged 3-5%. Compared with a solid-phase column extraction procedure, the overall time for sample preparation was decreased from 3 h down to 1. The SPEC extraction procedure with trimethyl derivatization produces a cleaner total ion chromatogram than the solid-phase column extraction system (minicolumn) and does not require the use of any organic solvents.

Immunohistochemical evidence for different pathways immunoreactive to substance P and calcitonin gene-related peptide (CGRP) in the guinea-pig stellate ganglion

The colocalization of immunoreactivities to substance P and calcitonin gene-related peptide (CGRP) in nervous structures and their correlation with other peptidergic structures were studied in the stellate ganglion of the guinea pig by the application of double-labelling immunofluorescence. Three types of fibre were distinguished. (1) Substance P+/CGRP+ fibres, which sometimes displayed additional immunoreactivity for enkephalin, constituted a small fibre population of sensory origin, as deduced from retrograde labelling of substance P+/CGRP+ dorsal root ganglion cells. (2) Substance P+/CGRP- fibres were more frequent; some formed baskets around non-catecholaminergic perikarya that were immunoreactive to vasoactive intestinal polypeptide (VIP). (3) CGRP+/substance P- fibres were most frequent and were mainly distributed among tyrosine hydroxylase (TH)-immunoreactive cell bodies. The peptide content of fibre populations (2) and (3) did not correspond to that of sensory ganglion cells retrogradely labelled by tracer injection into the stellate ganglion. Therefore, these fibres are thought to arise from retrogradely labelled preganglionic sympathetic neurons of the spinal cord, in which transmitter levels may have been too low for immunohistochemical detection of substance P or CGRP. CGRP-immunoreactivity but no substance P-immunolabelling was observed in VIP-immunoreactive postganglionic neurons. Such cell bodies were TH-negative and were spared by substance P-immunolabelled fibre baskets. Retrograde tracing with Fast Blue indicated that the sweat glands in the glabrous skin of the forepaw were the targets of these neurons. The streptavidin-biotin-peroxidase method at the electron-microscope level demonstrated that immunoreactivity to substance P and CGRP was present in dense-cored vesicles of 50-130 nm diameter in varicosities of non-myelinated nerve fibres in the stellate ganglion. No statistically significant difference in size was observed between vesicles immunolabelled for substance P and CGRP. Immunoreactive varicosities formed axodendritic and axosomatic synaptic contacts, and unspecialized appositions to non-reactive neuronal dendrites, somata, and axon terminals. Many varicosities were partly exposed to the interstitial space. The findings provide evidence for different pathways utilizing substance P and/or CGRP in the guinea-pig stellate ganglion.

Partial reversal of the effects of extradural clonidine by oral yohimbine in postoperative patients

Extradural clonidine produces analgesia, with sedation, hypotension and bradycardia, in postoperative patients. This study assessed if oral yohimbine would reverse these side effects. We studied 30 ASA I-II patients undergoing orthopaedic surgery. After operation they were allocated randomly to three groups to receive placebo, extradural clonidine 450 micrograms or extradural clonidine 450 micrograms plus oral yohimbine 16 mg. Pain score was measured on a visual analogue scale (VAS); sedation was assessed on a simple scale graded from 0 (awake and alert) to 3 (deeply sedated, awakening after tactile stimulations) and heart rate and arterial pressure were monitored for 5 h. Yohimbine reversed the sedation induced by extradural clonidine, but also shortened the duration of analgesia (31 (SD 15) min, 186 (72) min and 126 (52) min in the placebo, extradural clonidine and extradural clonidine+yohimbine groups, respectively) (P < 0.05), and did not reduce the hypotension and bradycardia related to clonidine administration. These results suggest that alpha 2 adrenoceptors are mediators of the sedation induced by clonidine and that the haemodynamic effects are not related to stimulation of supraspinal alpha 2 receptors.

Epidural clonidine decreases postoperative requirements for epidural fentanyl

OBJECTIVE

This study assesses the possibility that clonidine may decrease analgesic opioid demand in postoperative patients.

METHODS

Twenty-five patients were allocated randomly after abdominal surgery to receive either an epidural bolus dose of fentanyl (1.0 mcg.kg-1) followed by a 1.0 mcg.kg-1h-1 continuous epidural infusion, or an epidural bolus dose of fentanyl (1.0 mcg.kg-1) followed by a continuous epidural infusion combining fentanyl 0.5 mcg.kg-1 x h-1 and clonidine 0.3 mcg.kg-1 x h-1. Pain was assessed at definite intervals on a visual analog scale (VAS) over 3 postoperative days. Epidural infusion was halved when VAS score was lower than 2. Patients were monitored with a pulse oximeter over 12 hours during the first postoperative night. Plasma fentanyl was measured by radioimmunoassay when patients left the recovery room and at 8 a.m. on the first and the second postoperative days.

RESULTS

VAS scores were comparable in the two groups of patients. The amount of fentanyl delivered was significantly lower in the fentanyl + clonidine group, as were the plasma fentanyl concentrations. The duration of SaO2 < 90% episodes was significantly less prolonged in the fentanyl + clonidine group (3.5 +/- 4.8 minutes versus 14.4 +/- 14.6 minutes).

CONCLUSIONS

The combination of clonidine to epidural fentanyl allows a decrease in opioid requirements without impairing analgesia. Reduction of opioids administration may have beneficial effects on respiratory function in postoperative patients.

Radiosensitive Chinese hamster irs2 cells show enhanced chromosomal sensitivity to ionizing radiation and restriction endonuclease induced blunt-ended double-strand breaks

The Chinese hamster irs2 cell line shows cellular hypersensitivity to ionizing radiation although the induction and repair of double-strand breaks (dsb) in bulk DNA is normal. Here we report that irs2 shows chromosomal hypersensitivity to ionizing radiation and the restriction endonuclease PvuII. The ratio of induced chromosomal aberrations in irs2 versus V79 was similar to that for survival (factor of between 2 and 4). PvuII was administered during cell poration with the bacterial toxin streptolysin O. We also report that when streptolysin O porated irs2 and V79 cells were treated with PvuII, and dsb assayed by neutral filter elution, equivalent numbers of dsb were induced in the two lines as a function of time following treatment. Our data show that irs2 has a DNA damage processing defect that leads to enhanced conversion of blunt-ended dsb into visible chromosomal damage.

Prolonged placement of spinal catheters does not prevent postdural puncture headache

OBJECTIVE

To determine whether leaving an intrathecal catheter in place in the postoperative period prevents postdural puncture headache (PDPH).

METHODS

Lumbar puncture was performed with an 18-gauge Tuohy needle. 0.5% bupivacaine spinal anesthesia was given through a 20-gauge catheter in 87 patients having orthopedic surgery. Postoperatively, patients were allocated randomly to have the catheter immediately withdrawn (group 1, N = 47) or kept in place for 12 to 24 hours (group 2, N = 40). Patients were questioned by a blinded observer, about PDPH twice a day on postoperative days 1, 2, 3, and 8.

RESULTS

The incidence of PDPH was 9.2%, and this was comparable in the two groups (5 patients in group 1 and 3 patients in group 2).

CONCLUSION

Leaving the intrathecal catheter in place in the postoperative period for 12 to 24 hours does not prevent PDPH.

Cell-type specific interaction of Neu differentiation factor (NDF/heregulin) with Neu/HER-2 suggests complex ligand-receptor relationships

The Neu/HER-2 receptor tyrosine kinase is overexpressed in some types of human adenocarcinomas, including tumors of the breast and the ovary. A 44 kDa glycoprotein that elevates tyrosine phosphorylation of Neu has been isolated and named Neu differentiation factor (NDF), or heregulin. Here we show that NDF affects tyrosine phosphorylation of Neu in human tumor cells of breast, colon and neuronal origin, but not in ovarian cells that overexpress the receptor. By using monoclonal antibodies (mAbs) to Neu, we found that the ovarian receptor is immunologically and biochemically similar to the mammary p185neu. Nevertheless, unlike breast-derived Neu, the ovarian protein did not display covalent cross-linking to radiolabeled NDF, and was devoid of ligand-induced association with phosphatidylinositol 3'-kinase. Direct binding analysis showed that NDF binds with high affinity (Kd approximately 10(-9) M) to mammary cells, but its weak association with ovarian cells is probably mediated by heparin-like molecules. Similar to the endogenous receptor, the ectopically overexpressed Neu of mammary cells, but not of ovarian and fibroblastic cells, exhibited elevated levels of NDF-induced phosphorylation and covalent cross-linking of the radiolabeled factor. Taken together, our results imply that NDF binding to cells requires both Neu and an additional cellular component, whose identity is still unknown, but its tissue distribution is more restricted than the expression of the neu gene.

Transient translocation of the cytoplasmic (endo) domain of a type I membrane glycoprotein into cellular membranes

The E2 glycoprotein of the alphavirus Sindbis is a typical type I membrane protein with a single membrane spanning domain and a cytoplasmic tail (endo domain) containing 33 amino acids. The carboxyl terminal domain of the tail has been implicated as (a) attachment site for nucleocapsid protein, and (b) signal sequence for integration of the other alpha-virus membrane proteins 6K and E1. These two functions require that the carboxyl terminus be exposed in the cell cytoplasm (a) and exposed in the lumen of the endoplasmic reticulum (b). We have investigated the orientation of this glycoprotein domain with respect to cell membranes by substituting a tyrosine for the normally occurring serine, four amino acids upstream of the carboxyl terminus. Using radioiodination of this tyrosine as an indication of the exposure of the glycoprotein tail, we have provided evidence that this domain is initially translocated into a membrane and is returned to the cytoplasm after export from the ER. This is the first demonstration of such a transient translocation of a single domain of an integral membrane protein and this rearrangement explains some important aspects of alphavirus assembly.

Can portable chest x-ray examination accurately diagnose lung consolidation after major abdominal surgery? A comparison with computed tomography scan

PURPOSE

To prospectively quantify the degree of accuracy of portable chest x-ray film examination in the detection of postoperative lung consolidations.

STUDY

Nineteen patients had a chest x-ray film and computed tomography (CT) scan the day before and 48 h following elective abdominal aortic replacement.

RESULTS

The diagnosis of lung consolidations by x-ray film examination showed sensitivity of between 0.33 and 1.00, depending on the lung zone considered (lower at the lung bases). Specificity always was greater than 0.79. Radiologic lung volume decreased 16 percent postoperatively (p < 0.01) on average and noninflated parenchyma increased by a factor of 3 (p < 0.0001). Postoperatively, PaO2 correlated with the amount of condensed lung by CT scan (p < 0.002).

CONCLUSION

In postoperative conditions, x-ray film examination is a method which presents good specificity but poor sensitivity in the diagnosis of lung consolidations.

Effect of preoperative normovolemic hemodilution on left ventricular segmental wall motion during abdominal aortic surgery

Preoperative normovolemic hemodilution (PNH) has been proposed for patients scheduled to undergo aortic surgery. Coronary artery disease is frequent in these patients. The aim of the study was to assess the effect of PNH on hemodynamics and segmental wall motion (SWM) evaluated by transesophageal echocardiography in such patients. Twenty patients with coronary artery disease were allocated randomly to either PNH or no PNH; PNH was performed after anesthetic induction using dextran 60,000. Patients were operated on under general anesthesia and monitored intraoperatively with electrocardiographic lead CM5, radial and pulmonary artery catheters, and transesophageal echocardiography positioned to obtain a short-axis view. Hemodynamic and transesophageal echocardiographic data were collected after anesthetic induction and after PNH, before and 5 min after aortic clamping, after unclamping, and at the end of surgery. Aortic clamping induced a significant increase in systemic vascular resistance and arteriovenous difference in oxygen and a decrease in cardiac index (P < 0.05), but the effect of aortic clamping was inversely related to hemodilution. The SWM score (graded from 1 = normal to 5 = dyskinesia) was significantly increased after aortic clamping, mainly in the anterior segment (P < 0.05). Four patients in the control (no PNH) group and one in the PNH group developed new SWM abnormalities indicative of myocardial ischemia during surgery (P = NS). This study suggests that PNH may improve hemodynamic tolerance to aortic clamping in patients with coronary artery disease. The observed changes in SWM indicate that PNH may not worsen myocardial ischemia in patients scheduled to undergo aortic surgery.

Functional implication of disulfide bond, Cys250 -Cys283, in bovine chymosin

The reduction, carboxymethylation and mercuration of disulfide bond, Cys250-Cys283, located on the surface of bovine chymosin molecule resulted in the loss of about 25% of enzyme activity, suggesting that Cys250-Cys283 is not intimately involved in catalytic mechanism. Cys250 and Cys283 were substituted with Asp. and Ser. by site- directed mutagenesis of the structural gene coding for bovine prochymosin B. All three mutants (C250D/C283S, C250D, C283S) failed to be activated to chymosin in acid, indicating that Cys250-Cys283 might have some contribution to the correct refolding of the unfolded prochymosin.

Single- versus triple-lumen central catheter-related sepsis: a prospective randomized study in a critically ill population

PURPOSE

A prospective randomized study was conducted over a 23-month period in an adult medical-surgical intensive care unit to determine whether triple-lumen catheters reduce the need for peripheral vascular access and whether they are associated with a higher rate of infection than single-lumen catheters.

PATIENTS AND METHODS

After the insertion route, internal jugular or subclavian, was selected by the physician, patients were randomized either to single-lumen or triple-lumen catheter groups. Complementary peripheral vascular access was allowed in both groups. Catheters were removed according to preestablished defined reasons: suspicion of catheter-related sepsis, uselessness of central venous access, duration of catheterization of more than 21 days, discharge from the intensive care unit, or death.

RESULTS

Data on 129 central venous catheters were collected from 91 consecutive patients. Twenty-five of 68 patients from the single-lumen group and 1 of 61 patients from the triple-lumen group needed peripheral vascular access (p less than 0.001). Catheter-related sepsis rates, defined either by clinical signs and positive qualitative tip cultures (8.9% versus 11.5%) or by quantitative tip cultures (16.2% versus 11.5%), were identical in the single-lumen and triple-lumen groups (type II error: 8%).

CONCLUSION

In intensive care units, the use of triple-lumen catheters is associated with a dramatic decrease in the need for peripheral vascular access. The incidence of central venous catheter-related sepsis appears identical for single- and triple-lumen catheters.

[The effect of 211At labelled monoclonal antibody against gastric cancer on DNA, RNA and protein synthesis in gastric cancer cell]

By means of nuclide precursor incorporation, the effects of 211At labelled monoclonal antibody against gastric cancer (211At-3H11McAb) on DNA, RNA and protein synthesis in gastric cancer cell were studied. The results show that 211At-3H11McAb and Na211At-3 inhibit 3H-TdR, 3H-UR and 3H-Leu incorporation, especially 3H-UR incorporation, into gastric cancer cell at 3.7 x 10(4)Bq and 1.85 x 10(5)Bq; the inhibiting rates depend on concentration. The DNA biosynthesis in gastric cancer cell gradually recover after the drug is removed, suggesting that the drug should exert an inhibiting action on DNA biosynthesis in tumor cell through interference of DNA metabolism.

A dose-range study of intrathecal meperidine combined with bupivacaine

Twenty-one patients were included in a randomized study to receive either 10 mg of 0.5% hyperbaric bupivacaine alone or combined with 0.05, 0.1, 0.2, 0.3, 0.4 or 0.5 mg.kg-1 meperidine for spinal anaesthesia. Sensory blockade was assessed by pin prick, motor blockade by the Bromage scale, and postoperative analgesia by VAS scores and by the time before the first demand for analgesia. Spinal meperidine did not change the duration of sensory blockade, but induced a dose-related increase in postoperative efficient analgesia. Spinal meperidine might be considered as a means to obtain postoperative analgesia in the hours immediately following surgery.

Test of 20 similar intensive care ventilators in daily use conditions--evaluation of accuracy and performances

Infrequent control, aging of components, may compromise the accuracy of ICU ventilators. In order to assess the reliability of ventilators during their clinical use, we bench tested a group of 20 CPU1 ventilators (Ohmeda) sampled at random in several ICU units. We found major leaks in 5 ventilators, attributable to the disposable tubings used in these systems. Mean error in expired tidal volume and corresponding standard deviation (precision) were greater than 100 ml in two. Positive end expiratory pressure measurement comprised a mean error higher than 2 cm H2O in 40% of the ventilators tested. The valve opening pressure threshold was correlated to the inspiratory flow (r = 0.81) contrary to the valve opening delay (average 138 +/- 40 ms). These two parameters did not correlate with the age of the ventilator. Our study addresses the need for periodic control of ventilator performance in order to minimize the risks of errors and malfunctions.

[A study of 11 ventilators for anesthesia: laboratory testing]

Eleven anaesthesia ventilators were instrumentally tested under various conditions. They included: Excel and Modulus II Plus (Ohmeda); 710 and Servo anaesthesia circle 985 (Siemens); Jollytronic (Soxil) and Elsa (Engström); SA2 and Cicero (Dräger); ABT 4,300 (Kontron); Monnal A and the prototype Alys (Taema). The test circuit comprised a two compartment model lung, a pneumotachograph, a pressure gauge in the "airway". The volume was calculated as the integral of flow rate. Each machine was calibrated by the firms' technicians. Before each test, the pneumotachograph was calibrated using a 11 air syringe and the pressure gauge with a 5 cm water column. Each machine ventilated the model lung for 30 min before starting the tests. There were five tests: 1) reliability of the machine's spirometer, 2) reliability of the ventilation rate, 3) reliability of pressure measurements, 4) effect of increasing fresh gas flow on spirometry, 5) effect of increasing downstream resistances. In usual simulated ventilatory conditions, all the machines accurately delivered the setted ventilation and spirometric measurements were with minimal error only. Several ventilators (SA2, Excel, 710, Elsa, ABT 4,300) did not succeed in maintaining their performances when compliance was strongly decreased or resistance of the test lung notably increased. Resistance in the circuit during simulated spontaneous ventilation was < 3.6 cmH2O.l-1.s-1. Increasing fresh gas flow raised the minute volume delivered in six ventilators. It is concluded that, during extreme ventilatory conditions, the inspired volume must be adjusted so as to maintain the inspired tidal volume. However, ventilators which increase inspiratory time in response to an increased mechanical load cannot be adjusted by this way.

Selection of high-level abamectin resistance from field-collected house flies, Musca domestica

Abamectin is a novel, highly promising insecticide with activity against many pests. To determine if resistance to abamectin could occur, we collected house flies from several New York dairies and selected them in the laboratory. Resistance developed rapidly and to a high level (36 or greater than 60,000-fold, depending upon test technique and/or adjuvant) that could not be overcome by the synergists piperonyl butoxide or S,S,S-tributylphosphorotrithioate. There was no increase in (cross)resistance to crotoxyphos, dichlorvos, dimethoate, tetrachlorvinphos, permethrin, dieldrin or lindane following abamectin selection. Our results suggest the potential for abamectin resistance is high, at least in house flies, and that the judicious use of abamectin will be needed to prolong its usefulness as an insecticide.

Demonstration of immuno-bound alkaline phosphatase by a direct lead method. Optimization of reaction parameters by microdensitometry using computer-aided image processing

Antigens labelled by the immunohistochemical alkaline phosphatase anti-alkaline phosphatase (APAAP) method can be visualized by a lead capture technique. Optimal conditions of the reaction, evaluated by microdensitometry using computer-aided image processing, are described.

[Analysis of failures of spinal anesthesia as a function of practice development in a university hospital]

This study is a retrospective analysis of 303 consecutive spinal anaesthesia performed in orthopaedic patients of a University Hospital between January and December 1990. Failure of spinal anaesthesia was defined as the requirement for general anaesthesia to perform surgery. The parameters studied as possible risk factors of failure were patients demographics, local anaesthetic agents and solutions and techniques of spinal anaesthesia (single injection versus continuous spinal anaesthesia). Failures were related to inadequate or incomplete extension of sensory blockade or to difficulties to perform spinal injection. Continuous spinal anaesthesia was performed in 209 patients mostly with 0.5% isobaric bupivacaine, while 94 patients received a single injection of either hyperbaric 0.5% tetracaine with adrenaline or 0.5% bupivacaine or 5% lidocaine. Failures occurred in 6.3% of the cases but were significantly less frequent with continuous spinal anaesthesia (4.8%) than with the conventional technique (9.6%). The incidence of failure was higher with hyperbaric tetracaine (11.1%) confirming its poor reliability. Inadequate extension of the anaesthetic block was the main cause of failure whatever the spinal anaesthetic technique. These results point out the reliability of continuous spinal anaesthesia but problems may occasionally occur due to spinal catheter misplacement.

[Experimental study of glucosylated low density lipoprotein metabolism and atherosclerosis]

The effect of LDL glucosylation on its pathway was assessed. Human serum LDL was isolated by density gradient ultracentrifugation and its purity was identified by polyacrylamide gel electrophoresis. LDL was radioiodinated with 125I by iodine monochloride. LDL radioreceptor assay was performed and intracellular total cholesterol was determined in cultured human fibroblasts. Maximal binding affinity (Bmax) of LDL receptor was 47 ng LDL/mg cell protein, Km was 9.4 micrograms/ml. The receptor mediated binding, internalization and degradation of glucosylated LDL were significantly decreased compared with control LDL, but total cholesterol content of cultured fibroblasts incubated with glucosylated LDL was significantly higher than those incubated with control LDL. The results suggested that glucosylation of LDL might be an important mechanism for the high incidence of disturbed lipid metabolism and atherosclerosis in diabetic patients.