Mapping of the H7-serospecific domain of Escherichia coli flagellin

The amino acid sequences responsible for H7 and H23 flagellum serology have been identified by using a genetic approach. The H7-specific domain was located between amino acids 352 and 374 of the H7 flagellin. The sequencing data also demonstrated that the difference between the H7 and H23 flagellins in this region results from a single substitution at amino acid 366 (Ser-->Thr). The common epitopes for H7 and H23 were located between amino acids 284 and 366.

Generation and analysis of 280,000 human expressed sequence tags

We report the generation of 319,311 single-pass sequencing reactions (known as expressed sequence tags, or ESTs) obtained from the 5' and 3' ends of 194,031 human cDNA clones. Our goal has been to obtain tag sequences from many different genes and to deposit these in the publicly accessible Data Base for Expressed Sequence Tags. Highly efficient automatic screening of the data allows deposition of the annotated sequences without delay. Sequences have been generated from 26 oligo(dT) primed directionally cloned libraries, of which 18 were normalized. The libraries were constructed using mRNA isolated from 17 different tissues representing three developmental states. Comparisons of a subset of our data with nonredundant human mRNA and protein data bases show that the ESTs represent many known sequences and contain many that are novel. Analysis of protein families using Hidden Markov Models confirms this observation and supports the contention that although normalization reduces significantly the relative abundance of redundant cDNA clones, it does not result in the complete removal of members of gene families.

Multicenter study of target-controlled infusion of propofol-sufentanil or sufentanil-midazolam for coronary artery bypass graft surgery. Multicenter Study of Perioperative Ischemia (McSPI) Research Group

BACKGROUND

The use of target-controlled infusions of anesthetics for coronary artery bypass graft surgery has not been studied in detail. The effects of target-controlled infusions of propofol or sufentanil, supplemented by infusions of sufentanil or midazolam, respectively, were evaluated and compared.

METHODS

At 14 clinical sites, 329 patients were given a target-controlled infusion of propofol (n = 165) to produce effect-site concentration (Ce) of > or = 3-micrograms/ml or a target-controlled infusion of sufentanil (n = 164). Sufentanil or midazolam, respectively, also were infused. Systolic hypertension, hypotension, tachycardia, and bradycardia were assessed by measuring heart rate and blood pressure every minute during operation. Myocardial ischemia was assessed perioperatively by monitoring ST segment deviation via continuous three-lead Holter electrocardiography, and it was evaluated during operation by monitoring left ventricular wall motion abnormality via transesophageal echocardiography.

RESULTS

The measured cardiovascular parameters were satisfactory and usually similar for the patients receiving propofol-sufentanil or sufentanil-midazolam. The primary endpoint of the percentage of patients with intraoperative ST segment deviation (23 +/- 6% vs. 24 +/- 6%, P = 0.86) did not differ significantly between the two groups. The incidence of left ventricular wall motion abnormality shown on transesophageal echocardiography before (19 +/- 4% vs. 26 +/- 4%, P = 0.25) and after (23 +/- 4% vs. 31 +/- 5%, P = 0.32) cardiopulmonary bypass also did not differ significantly for the two groups. Changes in intraoperative target concentration were more frequent with propofol-sufentanil anesthetic than with sufentanil-midazolam (11.7 +/- 7.1 vs. 7.3 +/- 3.6, P < 0.001). The incidence of intraoperative hypotension (77% vs. 55%, P < 0.001), the use of inotropic/vasopressor medications (93% vs. 84%, P = 0.01), and the administration of crystalloids (2.8 +/- 1.4 L vs. 2.4 +/- 1.2 L, P < 0.001) were significantly greater in the propofol-sufentanil group. Conversely, the incidence of intraoperative hypertension (43% vs. 54%, P = 0.05) and the use of antihypertensive/vasodilator medications (70% vs. 90%, P < 0.001) were significantly less in the propofol-sufentanil group.

CONCLUSIONS

Target-controlled infusions of propofol or sufentanil, supplemented by infusions of sufentanil or midazolam, respectively, were suitable to provide anesthesia for coronary artery bypass graft surgery. Continuous monitoring revealed a high prevalence of hemodynamic abnormalities. Despite greater hypotension in the propofol-sufentanil group and greater hypertension in the sufentanil-midazolam group, episodes of myocardial ischemia were similar for both groups and were not temporally related to episodes of hemodynamic abnormalities.

Carcinogenic risks of inorganic arsenic in perspective

Induction of cancer by inorganic arsenic occurs inconsistently between species and between routes of exposure, and it exhibits different dose-response relationships between different target organs. Inhaled or ingested arsenic causes cancer in humans but not in other species. Inhaled arsenic primarily induces lung cancer, whereas ingested arsenic induces cancer at multiple sites, including the skin and various other organs. Cancer potency appears to vary by route of exposure (ingestion or inhalation) and by organ site, and increases markedly at higher exposures in some instances. To understand what might explain these inconsistencies, we reviewed several hypotheses about the mechanism of cancer induction by arsenic. Arsenic disposition does not provide satisfactory explanations. Induction of cell proliferation by arsenic is a mechanism of carcinogenesis that is biologically plausible and compatible with differential effects for species or differential dose rates for organ sites. The presence of other carcinogens, or risk modifiers, at levels that correlate with arsenic in drinking water supplies, may be a factor in all three inconsistencies: interspecies specificity, organ sensitivity to route of administration, and organ sensitivity to dose rate.

Peripheral kappa 1-opioid receptor-mediated analgesia in mice

When injected directly into the tail, U50,488H is a potent analgesic in the tailflick assay (ED50 3.1 micrograms). The analgesic activity is lost if the radiant heat is focused 1 cm away from the site of injection. The kappa 1-opioid receptor antagonist nor-binaltorphimine given systemically reverses the local analgesic response of U50,488H, but the antagonist is 100-fold more potent when injected directly into the tail. Intrathecal antisense treatment with a probe targeting the mRNA encoding the kappa 1-opioid receptor blocks the local analgesic actions of U50,488H in the tail, suggesting that U50,488H is acting on dorsal ganglia neurons.

Short-term recombinant human DNase in bronchiectasis. Effect on clinical state and in vitro sputum transportability

We report a double blind placebo-controlled phase II study of the efficacy and safety of nebulized recombinant human DNase (rhDNase) administered for 14 d to adults with bronchiectasis not caused by cystic fibrosis. All were in a stable clinical state at the commencement of the study, and they received (1) rhDNase 2.5 mg twice daily, (2) rhDNase once daily, or (3) placebo (excipient only) inhalation. The outcome measures were spirometry, subjective quality of life/dyspnea, and safety. We also measured the ciliary transportability of the sputum expectorated before and after the treatment period, using the mucus-depleted bovine trachea. The drug was well tolerated, but it produced no significant change in any of the outcome variables or in sputum transportability. When the drug was incubated with bronchiectatic sputum in vitro, a fall in transportability was observed. We discuss possible explanations for the lack of a measurable benefit from rhDNase in this study population, which appears to contrast with the improvements shown in cystic fibrosis using studies of similar design.

The importance of the dura in craniofacial surgery

The hypothesis of this study is that craniofacial procedures that rely on devascularization of cranial bone are successful largely because of the unique environment that the dura offers. This hypothesis was tested by sequentially labeling animals with tetracycline and studying the healing of cranial bone grafts when replaced immediately and when subjected to room air exposure for 90 minutes and contrasting healing in mature and immature animals. Bilateral parietal bone flaps were harvested from guinea pigs. On one side, the bone was replaced as a control, and on the other side, the dura was resected prior to replacing the bone flap. The animals were divided into four groups of five animals each. The first and second groups were immature animals (3 to 4 weeks of age), and the third and fourth groups were mature animals (4 to 6 months of age). In the first and third groups, the bone flaps were replaced immediately, and in the second and fourth groups, the bone flaps were exposed to room air for 90 minutes, since this has been shown to destroy surface osteocytes and simulates extreme exposure conditions that could occur in clinical situations. Sequential marking with tetracycline was performed to study the mineralization rate and overall matrix formation. Significantly decreased mineralization rates occurred in bone flaps not in contract with dura. In those bone flaps exposed to room air for 90 minutes, healing occurred only on the side where dura was present. The clinical implications of the importance of the dura in craniofacial procedures are discussed.

The effect of bacterial toxins on levels of intracellular adenosine nucleotides and human ciliary beat frequency

Toxins that slow ciliary beat are virulence determinants of bacteria that infect or invade ciliated epithelial surfaces. We have previously shown that the effect of the Pseudomonas aeruginosa toxin pyocyanin on ciliary beat is associated with a fall in intracellular cAMP and ATP. We have now investigated whether reduction in intracellular adenosine nucleotides might be a common mechanism of action of other bacterial toxins which slow ciliary beat. Two other P. aeruginosa toxins, 1-hydroxyphenazine (1-HP) and rhamnolipid, and two Haemophilus influenzae fractions produced by gel filtration of broth cultures were tested. The effect on human nasal epithelium ciliary beat frequency (CBF), and intracellular cAMP and ATP were measured, and the effect of two pharmacological agents, dibutyryl cAMP and salmeterol, on these changes was assessed. 1-HP, rhamnolipid and the two H. influenzae fractions slowed CBF before there was significant release of lactate dehydrogenase from the cells. The toxins also caused a fall in intracellular cAMP and ATP. Dibutyryl cAMP and salmeterol at the concentrations used do not increase baseline CBF, but diminished the fall in CBF and intracellular adenosine nucleotides. The cAMP and ATP levels in these studies were combined with those previously obtained with pyocyanin. there was a good correlation between cAMP and ATP levels and CBF. Bacterial toxins which slow CBF may act by causing a fall in intracellular adenosine nucleotides, and agents which stimulate cAMP may prevent toxin-induced slowing of ciliary beat.

Type-III procollagen assembly in semi-intact cells: chain association, nucleation and triple-helix folding do not require formation of inter-chain disulphide bonds but triple-helix nucleation does require hydroxylation

Procollagen assembly is initiated within the endoplasmic reticulum by three alpha-chains associating via their C-propeptides (C-terminal propeptides). To study the requirements for the association of procollagen monomers at synthesis we have reconstituted the initial stages in the folding, assembly and modification of procollagen using semi-permeabilized cells. By translating a type-III procollagen "mini-gene' which lacks part of the triple-helical domain, we demonstrate that these cells efficiently carry out the assembly of hydroxylated, triple-helical, procollagen trimers and allow the identification of specific disulphide-bonded intermediates in the folding pathway. Mutant chains, which lack the ability to form inter-chain disulphide bonds within the C-propeptide, were still able to assemble within this system. Furthermore, characterization of the trimeric molecules formed suggested that inter-chain disulphide bonds had formed within the C-telopeptide (C-terminal telopeptide). However, when hydroxylation of prolyl and lysyl residues was inhibited no inter-chain disulphide bonds were formed in the C-telopeptide, indicating that hydroxylation is required for the initial nucleation of the triple-helical domain. Mutant chains which lacked the ability to form inter-chain disulphide bonds within the C-propeptide or the C-telopeptide could still assemble to form trimeric triple-helical molecules linked by inter-chain disulphide bonds within the N-propeptide (N-terminal propeptide). These results indicate that inter-chain disulphide bond formation within the C-propeptide or the C-telopeptide is not required for chain association and triple-helix formation.

The effects of computer-assisted versus teacher-directed instruction on the multiplication performance of elementary students with learning disabilities

The acquisition of multiplication facts by 4 elementary students with learning disabilities was compared under two instructional delivery formats-teacher directed and computer assisted. The two interventions were compared in terms of opportunities to respond and success rate. All students mastered more facts in the teacher-directed condition. In addition, teachers provided many more opportunities to respond and showed a higher success rate than did the software program. Implications of teacher-directed and computer-assisted instruction are discussed in terms of efficacy and feasibility.

The biology of bacterial colonization and invasion of the respiratory mucosa

Despite being regularly exposed to particulate matter during breathing, which contains bacteria from the commensal flora in the nasopharynx and from the environment, the healthy lung is kept sterile by efficient defence mechanisms. Bacterial infections of the respiratory mucosa represent a dynamic interaction, to which both host and bacterial factors contribute. The abnormal host defences associated with chronic respiratory infections (e.g. cystic fibrosis and other forms of bronchiectasis) serve to emphasize their permissive role. The bacteria that cause bronchial infections possess a wide array of potential virulence factors that contribute to their pathogenicity. Many of these factors influence the mucociliary system, an important first-line defence mechanism. The multiplication, spread and persistence of bacteria within the bronchial lumen, and consequent damage to the epithelium, stimulates a chronic inflammatory response, which also impairs mucociliary clearance and damages lung tissue. A greater understanding of host-bacterial interactions during mucosal infections should in the future lead to the development of new therapies and treatment strategies.

Comparison of haemophilus influenzae type b interaction with respiratory mucosa organ cultures maintained with an air interface or immersed in medium

Haemophilus influenzae type b infection of immersed and air interface organ cultures for 24 h caused significant epithelial damage. Bacterial association with mucus, damaged epithelium, and unciliated cells was significantly higher in air interface than immersed organ cultures, and total bacterial association was 55.8 times greater. Bacteria exhibited tropism for mucus only on explants maintained with an air interface. We conclude that immersion of nasopharyngeal tissue in medium may influence bacterial interaction with the mucosal surface.

Breathlessness in an Afro-Caribbean woman

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Cardiovascular responses during sedation after coronary revascularization. Incidence of myocardial ischemia and hemodynamic episodes with propofol versus midazolam. Institutions of the McSPI Research Group

BACKGROUND

Propofol sedation offers advantages for titration and rapid emergence in the critically ill patient, but concern for adverse hemodynamic effects potentially limits its use in these patients. The current study compares the cardiovascular effects of sedation with propofol versus midazolam during the first 12 h after coronary revascularization.

METHODS

Three hundred fifty-one patients undergoing coronary revascularization were anesthetized using a standardized sufentanil/midazolam regimen, and assigned randomly to 12 h of sedation with either propofol or midazolam while tracheally intubated. The incidence and characteristics of hemodynamic episodes, defined as heart rate less than 60 or greater than 100 beats/min or systolic blood pressure greater than 140 or less than 90 mmHg, were determined using data electronically recorded at 1-min intervals. The presence of myocardial ischemia was determined using continuous three-channel Holter electrocardiography (ECG) and of myocardial infarctions (MI) using 12-lead ECG (Q wave MI, Minnesota Code) or creatine kinase isoenzymes (CK-MB) analysis (non-Q wave MI, peak CK-MB > 70 ng/ml, or CK-MB > 70 IU/I).

RESULTS

Ninety-three percent of patients in both treatment groups had at least one hemodynamic episode during the period of postoperative sedation. Propofol sedation resulted in a 17% lower incidence of tachycardia (58% vs. 70%, propofol vs. midazolam; P = 0.04), a 28% lower incidence of hypertension (39% vs. 54%; P = 0.02), and a greater incidence of hypotension (68% vs. 51%; P = 0.01). Despite these hemodynamic effects, the incidence of myocardial ischemia did not differ between treatment groups (12% propofol vs. 13% midazolam; P = 0.66), nor did its severity, as measured by ischemic minutes per hour monitored (8.7 +/- 5.8 vs. 6.2 +/- 4.6 min/h, propofol vs. midazolam; P = 0.19) or ischemic area under the curve (6.8 +/- 4.0 vs. 5.3 +/- 4.2; P = 0.37). The incidence of cardiac death (one per group), Q wave MI (propofol, n = 7; midazolam, n = 3; P = 0.27), or non Q wave MI (propofol, n = 16; midazolam, n = 18; P = 0.81) did not differ between treatment groups.

CONCLUSIONS

Hemodynamic episodes occur frequently in the first 12 h after coronary revascularization. Compared with a standard sedation regimen (midazolam), propofol sedation appears to modulate postoperative hemodynamic responses by reducing the incidence and severity of tachycardia and hypertension and increasing the incidence of hypotension. Both sedation regimens appear similarly safe with respect to myocardial ischemia. These findings indicate that propofol infusion provides effective sedation without deleterious hemodynamic effects in patients recovering from cardiac surgery.

Failed intubation revisited: 17-yr experience in a teaching maternity unit

We have reviewed 5802 Caesarean sections performed during general anaesthesia. Our use of general anaesthesia had decreased from 83% in 1981 to 23% in 1994. Despite this, the incidence of failed intubation has increased from 1 in 1984 to 1 in 250 in 1994. The problems associated with general anaesthesia in the obstetric population are increasing. Asians and African/Afrocaribbeans were represented disproportionately because of the increased use of general anaesthesia in these patients. Exposure of trainees to obstetric general anaesthetics has decreased by one-third.

Integrated-optical directional coupler biosensor

We present measurements of biomolecular binding reactions, using a new type of integrated-optical biosensor based on a planar directional coupler structure. The device is fabricated by Ag(+) - Na(+) ion exchange in glass, and definition of the sensing region is achieved by use of transparent fluoropolymer isolation layers formed by thermal evaporation. The suitability of the sensor for application to the detection of environmental pollutants is considered.

Anti-inflammatory, membrane-stabilizing interactions of salmeterol with human neutrophils in vitro

1. We have investigated the effects of salmeterol (0.3-50 microM) on several pro-inflammatory activities of human neutrophils in vitro. 2. Oxidant production by FMLP- and calcium ionophore (A23187)-activated neutrophils was particularly sensitive to inhibition by low concentrations (0.3-3 microM) of salmeterol, while the responses of phorbol myristate acetate- and opsonised zymosan-stimulated cells were affected only by higher concentrations (3-50 microM) of the drug. At these concentrations salmeterol is not cytotoxic, nor does it act as a scavenger of superoxide. 3. These anti-oxidative interactions of salmeterol with neutrophils were insensitive to propranolol but could be eliminated by washing the cells, or by pretreatment with low concentrations (1-2 microM) of the pro-oxidative, membrane-destabilizing phospholipids, lysophosphatidylcholine (LPC), platelet activating factor (PAF) and lysoPAF (LPAF). 4. At concentrations of 6.25-50 microM salmeterol interfered with several other activities of stimulated neutrophils, including intracellular calcium fluxes, phospholipase A2 activity and synthesis of PAF. 5. In an assay of membrane-stabilizing activity, salmeterol (25 and 50 microM) neutralized the haemolytic action of LPC, PAF and LPAF. 6. Of the other commonly used beta 2-adrenoceptor agonists, fenoterol, and formoterol, but not salbutamol, caused moderate inhibition of neutrophil oxidant generation by a superoxide-scavenging mechanism. However, unlike salmeterol, these agents possessed only weak membrane stabilizing properties. 7. We conclude that salmeterol antagonizes the pro-inflammatory, pro-oxidative activity of several bioactive lipids implicated in the pathogenesis of bronchial asthma, by a mechanism related to the membrane-stabilizing, rather than to the beta 2-agonist properties of this agent.

Ciliary disorientation alone as a cause of primary ciliary dyskinesia syndrome

Ciliary disorientation has been proposed as a variant of primary ciliary dyskinesia (PCD); cilia have normal ultrastructure and normal or near normal ciliary beat frequency (CBF) but lack efficacy because their beat direction is disorientated. We have identified 11 patients, including two siblings, with the clinical features of PCD, who satisfy these criteria. A chest radiograph, pulmonary function tests, nasal mucociliary clearance (NMCC), CBF, ciliary ultrastructure, and orientation were assessed in each subject. One patient had biopsies taken from the nose and both main bronchi. Eight patients had a computed tomography scan (CT) of the thorax; the clinical features were compatible with PCD. Cilia ultrastructure was normal and NMCC was absent in all cases. Mean CBF was normal (11.6-14.9 Hz) in five cases and slow in six (range 8.4-9.7 Hz). Ciliary beat pattern was stiff in seven cases, six of which had slow CBF. The cilia were disorientated when measured by both the central pair (range, 21.8 degrees - 26.4 degrees) and basal feet (range, 20.6 degrees - 28.9 degrees) compared with 16 normal controls (range, 11.0 degrees - 15.5 degrees and 12.3 degrees - 17.6 degrees, respectively). Two siblings had the clinical features of PCD and ciliary disorientation alone on repeated biopsies taken 10 yr apart. Orientation of cilia from the nose and bronchus was similar. Two cases had unchanged ciliary disorientation after 3 mo of treatment with antibiotics and topical corticosteroids. We concluded that ciliary disorientation alone can lead to the clinical syndrome of PCD.

A human respiratory-tissue organ culture incorporating an air interface

The immersion of respiratory tissue in organ cultures is unphysiologic and may influence the interactions of the tissue with experimental agents. We have assessed an organ culture of human nasal turbinate tissue with an air interface by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), with and without replacement of culture medium. Without replacement of medium, ciliary beat frequency (CBF) was normal (11.3 +/- 0.5 Hz) at 5 d, but fell significantly (p<0.05) to 7.9 +/- 0.8 Hz at 10 d. The degree of ciliation decreased significantly (p<0.05) at 4 and 10 d. Nuclear heterochromatin in all cell types was significantly (p<0.05) reduced at 5 d. Significant (p<0.05) mitochondrial abnormalities occurred in ciliated cells at 5 d and in both ciliated and unciliated cells at 10 d. With daily replacement of medium, CBF fell significantly (p<0.05) from 11.6 +/- 0.2 Hz at Time 0 to 10.6 +/- 0.3 Hz after 20 d. The proportions of ciliated and nonciliated cells did not change after 20 d, but the proportion of mucus cells was higher at 20 d (26.3 +/- 5.4%) than at Time 0 (9.8 +/- 2.7%). No mitochondrial abnormalities, changes in nuclear heterochromatin levels, or reduction in cilial density on ciliated cells were present. The amount of damaged epithelium was less at 20d (7.2 +/- 3.8%) than at Time 0 (19.0 +/- 5.8%). This model more closely reproduces physiologic conditions in vitro than do models involving the immersion of respiratory tissue in media. Its long viability will permit studies of virus and bacterial infections, and of the effects of pharmacologic agents and environmental factors.