Modeling Framework for the Generation of Synthetic RR Series during Atrial Arrhythmias.

We introduced a modeling framework for the generation of realistic ventricular interval (RR) series to be used in the validation of atrial arrhythmia detection algorithms. The framework included three previously proposed models, which reproduced the specific variability properties of RR series in normal sinus rhythm, atrial flutter (AFL) and atrial fibrillation (AF). Transitions between the three rhythms were governed by a three-state continuous-time Markov chain model, which could be tuned to obtain arrhythmic episodes of the requested length. As a representative application, the modeling framework was used to generate a database of RR series for the validation of a previously proposed AF detection algorithm, which was based on RR pattern similarity. The validation showed the deterioration of detector performance in presence of simulated AFL episodes. Thanks to the detailed reproduction of the specific features of the two most common atrial arrhythmias, our modeling framework may constitute a novel tool for the assessment and comparison of detection algorithm performance.

Anaesthesia management in patients with multiple chemical sensitivity syndrome.

Multiple Chemical Sensitivity (MCS) is characterised by the appearance of numerous and sometimes severe symptoms, when subjects are in contact with various chemicals and medicinal substances. Currently there are no useful guidelines for managing clinical issues and, specifically, anaesthesia for patients with MCS. This case report describes anaesthesia management in a patient affected by clinically documented MCS and a latex allergy, a candidate for a laparoscopic cholecystectomy operation.

[Possible and proved benefits of peridural analgesia]. / Benefici presunti e dimostrati dell'analgesia peridurale.

Regional anesthesia is supposed to be of some help in improving the outcome of surgical patients. Actually this assumption is largely accepted, even if clear scientific demonstrations have not been obtained. At present there are data showing the advantages, as to survival and complications, especially for major orthopedic surgery. These data have been shown by important and clarifying meta-analyses. Unfortunately, for other types of surgery, advantages have been scarcely demonstrated, due to the low number of patients involved in clinical trials. Anyway, it is underlined that regional anesthesia, and especially epidural block, is much more convenient for the patients than general anesthesia. It seems also convenient from the economic point of view, since the pharmaco-economic studies present in the literature showed the possibility to save money, using regional anesthesia and regional analgesia.

Hemodynamic variations during thoracic and abdominal stop-flow regional chemotherapy.

AIMS: The aim of this study was to study hemodynamic modifications during thoracic and abdominal stop-flow regional chemotherapy and to evaluate the need for routine hemodynamic monitoring during such kind of procedures. METHODS: Thirty patients, aged 17-67 years, ASA physical status II-III, scheduled for thoracic (group A, n = 15), and abdominal (group B, n = 15) stop-flow regional chemotherapy were enrolled. Heart rate (HR), electrocardiogram lead I and V(5), end tidal carbon dioxide (ETCO(2)), arterial oxygen saturation (SaO(2)), systolic, diastolic and mean arterial pressure (SBP, DBP, MAP), mean pulmonary arterial pressure (MPAP), pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP), cardiac output (CO), stroke volume (SV), stroke index (SI), systemic vascular resistance (SVR), pulmonary vascular resistance (PVR), left cardiac work (LCW), right cardiac work (RCW), left cardiac work index (LCWI), right cardiac work index (RCWI), cardiac index (CI), and body O(2) consumption (VO(2)) were recorded. RESULTS: After aortic and inferior vena cava endovascular occlusion (T(1)), a significant reduction of CO and SV, associated with an increase of CVP, MAP, PAPM and PCWP were observed. A concomitant reduction of CI and increase of SVR and PVR were registered. The VO(2) was significantly reduced compared to basal values in both groups. After deflating aortic and vena cava balloons (T(2)), CO, SV and CI increased with respect to basal value p < 0.05) whereas MAP, CVP, PAPM, PCWP and calculated parameters (SVR, PVR) showed a significant reduction compared to T(1). The oxygen consumption was significantly higher than that of basal values p < 0.05. After hemofiltration (T(3)), all hemodynamic variables were comparable with the basal values. Modifications of direct and calculated parameters, during the stop-flow period, showed a similar trend in both study groups, without any statistically significant difference. No ST modifications at ECG were noted during all perioperative period. CONCLUSIONS: The results of this study have confirmed in both groups, the safety of stop-flow regional chemotherapy procedure, despite endovascular occlusion of the aorta and inferior cava vein. The hemodynamic and oxygenation changes are reversible and did not produce any ST modifications at ECG during all perioperative period. Routine pulmonary artery catheterization is thus unnecessary, except in high cardiac risk patients.

Physicochemical characterisation of the pertussis vaccine.

The characterisation of an acellular pertussis vaccine composed of a genetically modified pertussis toxin, filamentous haemagglutinin and pertactin is described. The three antigens are submitted to a mild treatment with formaldehyde in the presence of lysine before their use in vaccine formulation. Characterisation is performed by amino acid analysis, SDS-PAGE, analytical size exclusion chromatography and, in the case of pertactin, isoelectrofocusing. The effect of some variables on pertactin formaldehyde treatment has been studied by means of isoelectrofocusing and mouse immunogenicity.

Mucosal and systemic immunogenicity of a recombinant, non-ADP-ribosylating pertussis toxin: effects of formaldehyde treatment.

The effect of formaldehyde treatment on the mucosal and systemic immunogenicity of the genetically detoxified pertussis toxin (PT-9K/129G) was investigated. Groups of BALB/c were immunized intranasally (i.n.) or subcutaneously (s.c.) with untreated, lightly formaldehyde treated (LFT) or heavily formaldehyde treated (HFT) recombinant pertussis toxin (PT) mutant, PT-9K/129G. Intranasal immunization with native PT-9K/ 129G induced significant levels of anti-toxin antibodies in serum and IgA anti-toxin responses in nasal and lung lavages of these mice. Similar local and systemic responses were observed following intransal immunization with LFT toxin. However, i.n. immunization with HFT toxin failed to induce a local IgA response and elicited a much diminished anti-toxin response in the serum. In contrast, the total antibody response following s.c. immunization was not significantly affected. In addition, i.n. immunization with native PT-9K/129G induced low but detectable levels of toxin neutralizing antibodies in the serum. These results show that native PT-9K/129G protein acts as a mucosal immunogen in mice and that this activity is greatly diminished by HFT of the protein.

Formaldehyde treatment of proteins can constrain presentation to T cells by limiting antigen processing.

Proteins to be used as vaccines are frequently treated with formaldehyde, although little is known about the effects of this treatment on protein antigenicity. To investigate the effect of formaldehyde treatment on antigen recognition by T cells, we compared the in vitro T-cell response to proteins that have been formaldehyde treated with the response to untreated proteins. We found that peripheral blood mononuclear cells from individuals vaccinated with three formaldehyde-treated proteins (pertussis toxin, filamentous hemagglutinin, pertactin) of Bordetella pertussis showed little or no response to the formaldehyde-treated proteins but proliferated very well in response to the corresponding untreated protein. These findings were further confirmed with CD4+ T-cell clones specific for defined epitopes of the bacterial proteins. We found that some epitopes are presented poorly or not at all when formaldehyde-treated proteins are used, whereas other epitopes are equally presented to T-cell clones when either formaldehyde-treated or untreated antigens are used. However, T-cell recognition could be restored by either antigen degradation before formaldehyde treatment or heat denaturation after such treatment. Parallel digestion with trypsin of both formaldehyde-treated and untreated proteins showed that fragments generated from the two forms of the same antigen were different in size. These results demonstrate that formaldehyde treatment can constrain antigen presentation to T cells and that this may be due to an altered proteolytic processing of formaldehyde-treated proteins.

Depression of liver metabolism and induction of cytokine release by diphtheria and tetanus toxoids and pertussis vaccines: role of Bordetella pertussis cells in toxicity.

A 24-h pretreatment of mice with diphtheria and tetanus toxoids and whole-cell pertussis vaccines depressed liver cytochrome P-450 and therefore prolonged hexobarbital-induced sleeping time in mice. The depression of liver drug metabolism by a cellular vaccine containing a mutated pertussis toxin was less marked than that induced by the wild-type vaccines, indicating that the mutated vaccine might have lower toxicity in this regard. The wild-type vaccines decreased microsomal P-450 levels by 50%, while the mutated whole-cell vaccine had a less marked effect (a decrease of 30%), paralleling the results obtained in sleeping time experiments. Furthermore, an acellular mutated vaccine did not affect liver drug metabolism, indicating a role of the whole bacterial cell in this side effect. All the cellular vaccines studied induced high serum interleukin-6 levels; on the other hand, the acellular mutated vaccine induced very low interleukin-6 levels, indicating that the whole bacterial cell is also important for interleukin-6 induction. All vaccines studied were very poor tumor necrosis factor inducers.

Nutrition support after total laryngectomy.

This study was performed to evaluate the influence of different nutrition supports (enteral vs parenteral) on nutritional status, postoperative complications, and length of hospitalization in patients undergoing total laryngectomy. Forty-eight patients were divided at random into two groups and received enteral nutrition support by percutaneous endoscopic gastrostomy with a casein and soy-based polymeric formula blended with a modular protein (group A) or a balanced formula in total parenteral nutrition given through a subclavian venous catheter (group B). The results show a satisfactory preservation of nutritional status after total laryngectomy and no significant differences in the nutritional parameters between groups fed enterally or parenterally; however, percutaneous endoscopic gastrostomy could avoid many problems related to enteral nutrition support for patients undergoing laryngectomy. This route of administration was well tolerated by all the patients and, moreover, the percutaneous endoscopic gastrostomy-related complications were clinically less significant than those associated with total parenteral nutrition; this fact could explain the longer hospitalization for group B (34 +/- 11 vs 26 +/- 11 days) (p < .05).

Immunogenicity of an acellular pertussis vaccine composed of genetically inactivated pertussis toxin combined with filamentous hemagglutinin and pertactin in infants and children.

We studied the immunogenicity of an acellular pertussis vaccine composed of genetically detoxified pertussis toxin (PT-9K/129G), filamentous haemagglutinin, and a 69-kilodalton protein, pertactin, in 30 children aged 12 to 24 months and in 80 infants aged 2 to 4 months. A significant increase of the neutralizing titer and of the titers against pertussis toxin, filamentous hemagglutinin, and pertactin, as determined by enzyme-linked immunosorbent assay, was achieved after three doses of vaccine in all the children; a significant increase of these antibody titers was obtained in 100%, 96.1%, 93.5%, and 98.7% of the infants, respectively.

Preparation and immunogenicity of an inactivated hepatitis A vaccine.

A hepatitis A vaccine was prepared by formaldehyde inactivation of purified hepatitis A virus (HAV) LSH/S strain grown on human diploid MRC-5 cells. The vaccine was devoid of residual infectivity in vitro and failed to induce in marmoset monkeys any pathological features or variations of haematological and clinical chemistry values. Infectious HAV particles were not detected in faeces and sera of the vaccinated primates by ELISA or after passages in MRC-5 cells. The immunogenicity of the vaccine was evaluated by injecting guinea-pigs with 0.8, 0.2 or 0.05 micrograms of HAV antigen adsorbed onto 0.5 and 1 mg of Al (OH)3 or 0.3 mg of AlPO4. The antibody response, measured by a competitive radioimmunoassay, was dose- and adjuvant-dependent. One injection of 0.2 micrograms of AlPO4-adsorbed HAV antigen induced seroconversion in 100% of animals and high levels of specific and neutralizing serum antibodies. A further increase of antibody titres was observed after the second and third inoculations. These results show that this vaccine formulation is safe and immunogenic in animal models, and suggest that it should be evaluated further by human clinical studies.

Acellular pertussis vaccine composed of genetically inactivated pertussis toxin: safety and immunogenicity in 12- to 24- and 2- to 4-month-old children.

To determine whether a nontoxic derivative of pertussis toxin obtained by recombinant DNA technology, PT-9K/129G, is a good candidate for a new pertussis vaccine, we examined the safety and the immunogenicity in children of a vaccine containing 15 micrograms of PT-9K/129G protein and 0.5 mg of aluminum hydroxide per dose. Fifty-three children 12 to 24 months of age and 21 infants aged 2 to 4 months were injected with two and three doses, respectively. The vaccine did not induce significant local or systemic reactions and elicited an increase of antibody titer in more than 98% of the children. The geometric mean of the toxin-neutralizing titers increased after each dose and was 85 units in children given two doses and 196 units in those given three doses. Two children who had detectable antibody levels before the first immunization had a high response (greater than 320 units) to the first vaccine dose. The findings suggest that PT-9K/129G is a promising antigen to be included in the development of acellular pertussis vaccines.

Cellular pertussis vaccine containing a Bordetella pertussis strain that produces a nontoxic pertussis toxin molecule.

Bordetella pertussis 165-9K/129G, which produces a nontoxic form of pertussis toxin (PT), was used to prepare a whole-cell diphtheria-tetanus-pertussis (DTP) vaccine. The in vivo potency and the serological response induced by this vaccine were comparable to those of the conventional DTP vaccine which contains active PT. The toxic activities induced by PT such as leukocytosis, histamine sensitivity, and potentiation of anaphylactic reactions, which are present in the conventional DTP vaccine, were absent in the new vaccine. These results suggest that the introduction of a whole-cell vaccine containing B. pertussis 165-9K/129G would induce the same immunity as the conventional vaccine and would avoid the administration of a harmful toxin to children.

Phase I clinical trial of an acellular pertussis vaccine composed of genetically detoxified pertussis toxin combined with FHA and 69 kDa.

An acellular pertussis vaccine composed of genetically detoxified pertussis toxin (PT-9K/129G), filamentous haemagglutinin (FHA) and pertactin (69 kDa protein) was evaluated in adult volunteers, in double blind, versus placebo. No fever was reported in either group. Mild local reactions were reported after injection of both vaccine and placebo. After the first dose a marked increase in antibodies to PT, FHA and 69 kDa protein was seen in vaccinated subjects with the exception of one who responded well to PT and FHA but did not show a humoral response to the 69 kDa protein. All vaccinees acquired cellular immunity against the three antigens. No significant variation was observed in the humoral or cellular responses after the second dose.

Properties of pertussis toxin mutant PT-9K/129G after formaldehyde treatment.

Formaldehyde treatment is a method routinely used to detoxify diphtheria, tetanus, and pertussis toxins as well as other molecules suitable for vaccine production. To investigate whether chemical detoxification alters the immunological properties of vaccine components, we have treated the pertussis toxin mutant PT-9K/129G with formaldehyde and tested the properties of the resulting molecules. Very low concentrations of formaldehyde stabilize the molecule without affecting the physicochemical and immunological parameters. Increasing doses of formaldehyde abolish the mitogenic and hemagglutinating activities of PT-9K/129G. At the same time, the molecule loses the ability to be recognized by a monoclonal antibody specific for a major protective epitope on the S1 subunit of pertussis toxin and its affinity for anti-pertussis toxin polyclonal antibodies is also reduced. In marked contrast, the ability of PT-9K/129G to be recognized by human T-cell clones is not affected by Formalin treatment. In vivo, the formaldehyde-treated molecules induce amounts of specific antibodies comparable with those of untreated molecules but significantly lower levels of toxin-neutralizing antibodies. Furthermore, the formaldehyde-treated molecules also show a reduced protective activity in the intracerebral challenge assay.

Characterization of genetically inactivated pertussis toxin mutants: candidates for a new vaccine against whooping cough.

the introduction of two amino acid substitutions within the enzymatically active subunit S1 of pertussis toxin (PT) abolishes its ADP-ribosyltransferase activity and toxicity on CHO cells (Pizza et al., Science 246:497-500, 1989). These genetically inactivated molecules are also devoid of other in vivo adverse reactions typical of PT, such as induction of leukocytosis, potentiation of anaphylaxis, stimulation of insulin secretion, and histamine sensitivity. However, the mutant PT molecules are indistinguishable from wild-type PT in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and maintain all the physical and chemical properties of PT, including affinity for toxin-neutralizing poly- and monoclonal antibodies. Either alone or stabilized with formaldehyde, PT mutants are able to induce high levels of neutralizing antibodies and to protect mice in a dose-dependent fashion against intracerebral challenge with virulent B. pertussis. These results clearly show that these genetically inactivated PT molecules are nontoxic but still immunogenic and justify their development as a component of a new, safer acellular vaccine against whooping cough.