Single-channel electroencephalography of epileptic seizures in the out-of-hospital setting: an observational study.

OBJECTIVES: To evaluate whether single-channel electroencephalography (EEG) recording can be conducted in the out-of-hospital setting and whether it can be used to record electrographic signs of convulsive epileptic seizures. METHODS: This prospective observational feasibility study included patients who presented with a recent or ongoing epileptic seizure during out-of-hospital emergency treatment. Bifrontal single-channel EEG recordings were conducted by ambulance physicians throughout the initial treatment. The data recorded were analysed for the quality of recording and the occurrence of ictal EEG patterns. RESULTS: There were 45 adult patients who had a recent or an ongoing epileptic seizure in the study group and 15 patients with no neurological disorders in the control group. The median percentage of time during which no artefacts were detected by the device was 88.0% in the study group and 96.0% in the control group. EEG recordings for 3 out of 45 (6.6%) patients were of poor quality and not evaluable. Spike/wave or polyspike patterns were found in 98% and 100% of patients in the study and control groups, respectively, whereas the occurrence of periodic epileptiform discharges and delta waves with spikes showed a sensitivity and specificity of 100% (10/10) for the presence of an ongoing epileptic seizure. CONCLUSIONS: Single-channel EEG can be performed outside the hospital and yields useful recordings in most patients with acceptable rates of artefact. The diagnosis of generalised convulsive epileptic seizures by offline analysis of out-of-hospital EEG showed a high sensitivity and specificity when compared with the clinical diagnosis.

Electroencephalography during out-of-hospital cardiopulmonary resuscitation.

BACKGROUND: At the present time there is no parameter that can estimate the quality of cerebral perfusion and possible success of cerebral resuscitation during advanced cardiac life support (ACLS) efforts. In recent years, various attempts have been made to use electroencephalography (EEG)-based cerebral neuromonitoring to assess the effectiveness of cardiopulmonary resuscitation (CPR). OBJECTIVES: The Cerebral State Monitor M3 (Danmeter A/S, Odense, Denmark) is a portable, single-channel EEG monitor that provides the user with different EEG-based parameters and the raw waveform EEG to measure cerebral activity. CASE REPORT: We report two cases of out-of-hospital CPR with single-channel EEG monitoring conducted parallel to ACLS with external chest compressions. We demonstrate an artifact in waveform EEG recordings that is caused by the external chest compressions, and that leads to a miscalculation of the Burst Suppression Ratio and Cerebral State Index. CONCLUSION: These cases suggest that digitally processed EEG-monitoring is not a useful tool during CPR.

Single-channel amplitude integrated EEG recording for the identification of epileptic seizures by nonexpert physicians in the adult acute care setting.

OBJECTIVE: Although several studies have shown the potential of amplitude integrated electroencephalography (aEEG) in detecting neonatal seizures, no publications have evaluated the diagnostic use of aEEG for the detection of seizures in adult patients. METHODS: In this prospective blinded observational study, bifrontal single-channel electroencephalography (EEG) recordings were performed with a portable EEG monitor (CSM M3 ICU, Danmeter-Goalwick Holdings Limited, Odense, Denmark) during the out-of-hospital care of emergency cases. Four intensive care unit (ICU) physicians received training in the interpretation of aEEG recordings. After the training they evaluated the stored aEEG traces for the presence of epileptic seizure activity during the recording time. The physicians were blinded to the clinical data of the patients. The results obtained were compared with the clinical diagnosis and the evaluation of the raw EEG signal. The level of interrater agreement was quantified using Fleiss' ĸ. RESULTS: The aEEG traces from 10 patients with generalized epileptic seizures and 46 patients without seizures were analysed. Overall, the nonexpert ICU physicians failed to identify recordings obtained from patients with seizures reliably, when compared with clinical diagnosis and the single-channel EEG results (mean sensitivity 40%, range 40-60%; mean specificity 89%, range 87-93%). Agreement between observers was high for the cases with seizures ( ĸ = 0.80 ± 0.13). Patients who suffered status epilepticus during the recordings were difficult to identify by most raters. CONCLUSION: Recording of aEEG without access to the raw EEG data is not a reliable diagnostic tool for the identification of epileptic seizures in the hands of nonexpert ICU physicians.

Comparison of the over-the-head, lateral and alternating positions during cardiopulmonary resuscitation performed by a single rescuer with a bag--valve--mask device.

BACKGROUND: The 2005 guidelines for cardiopulmonary resuscitation (CPR) do not include a statement on performance of basic life support by a single healthcare professional using a bag-valve-mask device. Three positions are possible: chest compressions and ventilations from over the head of the casualty (over-the-head CPR), from the side of the casualty (lateral CPR), and chest compressions from the side and ventilations from over the head of the casualty (alternating CPR). The aim of this study was to compare CPR quality of these three positions. METHODS: 102 healthcare professionals were randomised to a crossover design and performed a 2-min CPR test on a manikin for each position. RESULTS: The hands-off time over a 2-min interval was not significantly different between over-the-head (median 31 s) and lateral (31 s) CPR, but these compared favourably with alternating CPR (36 s). Over-the-head CPR resulted in significantly more chest compressions (155) compared with lateral (152) and alternating CPR (149); the number of correct chest compressions did not differ significantly (119 vs 122 vs 109). Alternating CPR resulted in significantly less inflations (eight) compared with over-the-head (ten) and lateral CPR (ten). Lateral CPR led to significantly less correct inflations (three) compared with over-the-head (five) and alternating CPR (four). CONCLUSIONS: In the case of a single healthcare professional using a bag-valve-mask device, the quality of over-the-head CPR is at least equivalent to lateral, and superior to alternating CPR. Because of the potential difficulties in bag-valve-mask ventilation in the lateral position, the authors recommend over-the-head CPR.

A comparison between over-the-head and standard cardiopulmonary resuscitation performed by two rescuers: a simulation study.

BACKGROUND: In cardiopulmonary resuscitation (CPR) of a patient with an unsecured airway performed by two health care professionals, two methods are possible: 1) Standard CPR according to the guidelines, with one rescuer performing chest compressions from the side and the other rescuer performing ventilations from over the head of the patient. Additional tasks (like attaching the electrocardiogram and defibrillator) must be performed by the second rescuer during the time between ventilations. 2) Over-the-head CPR, with one rescuer performing chest compressions and ventilations from over the head and the other rescuer performing additional tasks. OBJECTIVES: The aim of this study was to compare the quality of CPR achieved by the two methods. METHODS: After a standardized theoretical introduction and practical training, 106 medical students with limited knowledge and training in CPR participated in this randomized crossover study. Students performed a 2-min CPR test of standard CPR in both positions and over-the-head CPR alone on a manikin. RESULTS: Standard CPR led to a significantly shorter hands-off-time over a 2-min interval than over-the-head CPR (median 25 s [interquartile range (IQR) 22-26 s] vs. 38 s [IQR 36-43 s], respectively, p < 0.001), and significantly more chest compressions (167 [IQR 158-176] vs. 142 [IQR 132-150], respectively, p < 0.001), more correct chest compressions (72 [IQR 11-136] vs. 45 [IQR 13-88], respectively, p = 0.004), inflations (10 [IQR 10-10] vs. 8 [IQR 8-8], respectively, p < 0.001), and correct inflations (5 [IQR 2-7] vs. 3 [IQR 1-4], respectively, p < 0.001). CONCLUSIONS: In the case of a two-professional-rescuer CPR scenario, standard CPR enables a quantitatively better resuscitation than over-the-head CPR.

Bivalvulidan (Myxozoa: Myxosporea) parasites of damselfishes with description of twelve novel species from Australia's Great Barrier Reef.

Bivalvulidan parasites from the gall bladder of 31 species of damselfishes (family Pomacentridae) were examined for their taxonomic identity and their relatedness to other species of myxozoans. This paper describes 11 novel ceratomyxid species and a novel Myxidium sp. Each species is characterized morphologically and small subunit (SSU) rDNA sequences were used in molecular phylogenetic analyses. Five pomacentrid species were found to harbour multiple infections of bivalvulidan species. One species of Ceratomyxa and Myxidium were found to infect more than a single species of damselfish. Phylogenetic analyses revealed there has been no radiation of ceratomyxids that can be associated with the fish host taxon and that Myxidium queenslandicus n.sp. was more closely related to Zschokkella mugilis and Ellipsomyxa gobii than other members of the genus Myxidium.

Identification of sensory blockade by somatosensory and pain-induced evoked potentials.

BACKGROUND: To date, the anesthesia-induced blockade of nociceptive inputs is insufficiently reflected by commercially available electroencephalographic depth-of-anesthesia monitors. The aim of the current study was to evaluate the potential of somatosensory (SSEP) and intracutaneous pain evoked (iSEP) potentials during remifentanil and propofol anesthesia as electroencephalographic indicators of the nociceptive blockade. METHODS: Ten healthy men were investigated in a double-blind crossover design during three sessions with remifentanil, propofol, and placebo administration. All dosages were increased in a step-by-step mode. SSEP and iSEP recordings were performed followed by subjective pain ratings and measurement of level of sedation (modified Observer's Assessment of Alertness and Sedation Scale). Changes from baseline in evoked potential components, pain ratings, and sedation scale were assessed by Bonferroni-Holms-corrected Wilcoxon tests. RESULTS: Pain ratings were significantly reduced by remifentanil. Sedation scale was significantly reduced by propofol. Early SSEP components were not affected by medication. The amplitudes of the long latency SSEP components increased significantly with remifentanil, decreased with propofol, and did not change with placebo. The amplitudes of long latency components of the iSEP decreased significantly with both remifentanil and propofol and did not change with placebo. CONCLUSION: Long latency components of the SSEP are differently affected by remifentanil and propofol administration. Further studies are needed to clarify whether they can serve as a specific indicator of the nociceptive blockade during anesthesia.

Asymmetric and axisymmetric constant curvature liquid-gas interfaces in pulmonary airways.

Airway closure and gas trapping can occur during lung deflation and inflation when fluid menisci form across the lumina of respiratory passageways. Previous analyses of the behavior of liquid in airways have assumed that the airway is completely wetted or that the contact angle of the liquid-gas interface with the airway wall is 0 degrees, and thus that the airway fluid forms an axisymmetric surface. However, some investigators have suggested that liquid in the airways is discontinuous and that contact angles can be as high as 67 degrees. In this study we consider the characteristics of constant curvature surfaces that could form a stable liquid-gas interface in a cylindrical airway. Our analysis suggests that, for small liquid volumes, asymmetric droplets are more likely to form than axisymmetric toroids. In addition, if the fluid contact angle is greater than 13 degrees, asymmetric droplets can sustain larger liquid volumes than axisymmetric toroids before collapsing to form menisci. These results suggest that (1) fluid formations other than axisymmetric toroids could occur in the airways; and (2) the analysis of the behavior of fluids and the development of liquid menisci within the lungs should include the potential role of asymmetric droplets.

Comparative evaluation of the Datex-Ohmeda S/5 Entropy Module and the Bispectral Index monitor during propofol-remifentanil anesthesia.

BACKGROUND: Different analytical concepts were introduced to quantify the changes of the electroencephalogram. The Datex-Ohmeda S/5 Entropy Module (Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland) was the first commercial monitor based on the entropy generating two indices, the state entropy (SE) and the response entropy (RE). The aim of the current study was to compare the accuracy of SE and RE with the Bispectral Index(R) monitor (BIS(R); Aspect Medical Systems, Newton, MA) during propofol-remifentanil anesthesia. METHODS: The authors investigated 20 female patients during minor gynecologic surgery. SE, RE, BIS, mean arterial blood pressure, heart rate, and sedation level were recorded every 20 s during stepwise increase (target-controlled infusion, 0.5 microg/ml) of propofol until the patients lost response. Five minutes after loss of response, remifentanil infusion (0.4 microg . kg(-1) . min(-1)) was started. Spearman correlation coefficient and prediction probability were calculated for sedation levels with SE, RE, BIS, mean arterial blood pressure, and heart rate. The ability of the investigated parameters to distinguish between the anesthesia steps awake versus loss of response, awake versus anesthesia, anesthesia versus first reaction, and anesthesia versus extubation was analyzed with the prediction probability. RESULTS: SE correlates best with sedation levels, but no significant differences of the prediction probability values among SE, RE, and BIS were found. The prediction probability for all investigated steps of anesthesia did not show significant differences among SE, RE, and BIS. SE, RE, and BIS were superior to mean arterial blood pressure and heart rate. CONCLUSION: SE, RE, and BIS revealed similar information about the level of sedation and allowed the authors to distinguish between different steps of anesthesia. Both monitors provided useful additional information for the anesthesiologist.

Comparative evaluation of Narcotrend, Bispectral Index, and classical electroencephalographic variables during induction, maintenance, and emergence of a propofol/remifentanil anesthesia.

UNLABELLED: In the present study, we sought to compare the abilities of Narcotrend (NT) with the Bispectral Index (BIS) electroencephalographic system to monitor depth of consciousness immediately before induction of anesthesia until extubation during a standardized anesthetic. We investigated 26 patients undergoing laminectomy. Investigated states of anesthesia were: awake, loss of response, loss of eyelash reflex, steady-state anesthesia, first reaction, and extubation during emergence. NT, BIS, spectral edge frequency, median frequency, relative power in delta, theta, alpha, beta, and hemodynamics were recorded simultaneously. The ability of all variables to distinguish between awake versus loss of response, awake versus loss of eyelash reflex, awake versus steady-state anesthesia, steady-state anesthesia versus first reaction and extubation were analyzed with the prediction probability. Effects of remifentanil during propofol infusion were investigated with Friedman's and post hoc with Wilcoxon's test. Only NT and BIS were able to distinguish all investigated states accurately with a prediction probability >0.95. After start of remifentanil infusion, only hemodynamics changed statistically significantly (P < 0.05). NT and BIS are more reliable indicators for the assessment of anesthetic states than classical electroencephalographic variables and hemodynamics, whereas the analgesic potency of depth of anesthesia could not be detected by NT and BIS. IMPLICATIONS: The modern electroencephalographic monitoring systems Narcotrend and Bispectral Index are more reliable indicators for the assessment of anesthetic states than classical electroencephalographic and hemodynamic variables to predict anesthetic conditions from before induction of anesthesia until extubation during a standardized anesthetic regime with propofol and remifentanil. The analgesic potency of depth of anesthesia could not be detected by Narcotrend and Bispectral Index.

Alaris AEP monitor's "Click Detection" does not help to detect inadvertent disconnection of headphones during anesthesia.

UNLABELLED: Auditory evoked potentials (AEP) can be suppressed by anesthetics dose dependently, but may fail to be registered because of the absence of adequate auditory stimuli. The Alaris AEP monitor includes the "Click Detection" (CD) (generating the message "NO AEP" or "LOW AEP") to detect the loss of auditory stimuli. We investigated the accuracy of the CD in 17 patients awake (AWAKE) and during anesthesia (ANESTHESIA) with accurately placed headphones (HP) and after disconnected HP (No HP) over 5 min each, respectively. Alaris AEP ARX index, CD, and Bispectral Index were recorded each minute. Changes were evaluated with the Friedman and Wilcoxon test. Sensitivity (SEN) and specificity (SPE) and receiver operating characteristic curve were analyzed for the accuracy of the CD. During AWAKE after disconnection of the HP, Alaris AEP ARX index decreased significantly (P < 0.05). The CD was able to detect No HP after 2 min with a SEN of 88% and a SPE of 97%. During ANESTHESIA, no changes were found after HP disconnection. CD detected No HP with a SEN of 100% and a SPE of 20%. The CD of the Alaris AEP monitor is not able to detect unnoticed disconnection of HP during ANESTHESIA. IMPLICATIONS: Signal transmission of auditory evoked potentials can be suppressed by anesthetics, but also by disconnection of headphones. In the present study, we demonstrate that even the Alaris AEP monitor with the very new feature "Click Detection" was not able to detect the loss of headphones during general anesthesia with propofol and remifentanil.

Narcotrend and Bispectral Index monitor are superior to classic electroencephalographic parameters for the assessment of anesthetic states during propofol-remifentanil anesthesia.

BACKGROUND: A new electroencephalogram monitor, the Narcotrend, was developed to measure anesthetic depth. The authors compared the Narcotrend, the Bispectral Index, and classic electroencephalographic and hemodynamic parameters during anesthesia with propofol and remifentanil. METHODS: The authors investigated 25 patients undergoing laminectomy at different anesthetic states: awake, steady state anesthesia, first reaction during emergence, and extubation. Narcotrend value; BIS; relative power (percent) in delta, theta, alpha, and beta; median frequency; spectral edge frequency; and hemodynamic parameters were recorded simultaneously. The ability of the classic and processed electroencephalographic and hemodynamic parameters to predict the clinically relevant anesthetic states of awake, steady state anesthesia, first reaction, and extubation was tested using prediction probability. RESULTS: Only the Narcotrend was able to differentiate between awake versus steady state anesthesia and steady state anesthesia versus first reaction/extubation with a prediction probability value of more than 0.90. CONCLUSIONS: Modern electroencephalographic parameters, especially Narcotrend, are more reliable indicators for the clinical assessment of anesthetic states than classic parameters.

ARX-derived auditory evoked potential index and bispectral index during the induction of anesthesia with propofol and remifentanil.

UNLABELLED: A new commercial auditory evoked potential (AEP) monitor (A-line AEP monitor) was developed to calculate an index (ARX AEP index; AAI) by automatically using the amplitudes and latencies of the AEP. We investigated 30 patients before spine surgery. AAI; bispectral index (BIS); relative (%) delta, theta, alpha, and beta; spectral edge frequency; median frequency; mean arterial blood pressure; heart rate; and oxygen saturation were obtained simultaneously during stepwise (1.0 micro g/mL) induction of target-controlled propofol concentration until 5.0 micro g/mL, followed by an infusion of 0.3 micro g. kg(-1). min(-1) of remifentanil. Every minute, the patients were asked to squeeze the observer's hand. Prediction probability (Pk), receiver operating characteristic, and logistic regression were used to calculate the probability to predict the conditions AWAKE, UNCONSCIOUSNESS (first loss of hand squeeze), and steady-state ANESTHESIA (5.0 micro g/mL of propofol and 0.3 micro g. kg(-1). min(-1) of remifentanil). Although a statistically significant difference among the conditions was observed for AAI, BIS, mean arterial blood pressure, median frequency, and %alpha, only AAI and BIS were able to distinguish UNCONSCIOUSNESS versus AWAKE and ANESTHESIA versus AWAKE with better than Pk = 0.90. The modern electroencephalographic variables AAI and BIS were superior to the classic electroencephalographic and hemodynamic variables to distinguish the observed anesthetic conditions. IMPLICATIONS: The modern electroencephalographic ARX-derived auditory evoked potential index and the bispectral index were superior to the classic electroencephalographic and hemodynamic variables for predicting anesthetic conditions. Variables derived from the auditory evoked potential did not provide an advantage over variables derived from spontaneous electroencephalogram.

Narcotrend, bispectral index, and classical electroencephalogram variables during emergence from propofol/remifentanil anesthesia.

UNLABELLED: The aim of this study was to investigate modern and classical electroencephalographic (EEG) variables in response to remifentanil and propofol infusions. We hypothesized that modern EEG variables may indicate the effects of propofol but not of remifentanil. Twenty-five patients were included in the study after the end of elective spine surgery without any surgical stimulation. Baseline values were defined with remifentanil 0.3 microg. kg(-1). min(-1) and target-controlled infusion of propofol 3.0 microg/mL. EEG changes were evaluated 1, 3, 5, 7, and 9 min after the stop of remifentanil infusion, followed by a step-by-step reduction (0.2 microg/mL) every 3 min of target-controlled infusion propofol. Narcotrend (NT; classifying EEG stages from awake to deep anesthesia), bispectral index (BIS), EEG spectral frequency bands (%), 50% (Median) and 95% percentiles (spectral edge frequency), mean arterial blood pressure, heart rate, and oxygen saturation were detected at every time point. The end of remifentanil application resulted in significant increases in %alpha, spectral edge frequency, mean arterial blood pressure, and %theta and decreases in %delta (P < 0.05). NT, BIS, Median, heart rate, and oxygen saturation were unchanged. Decreases in propofol concentration were associated with statistically significant increases in NT and BIS (P < 0.05). Thus, the sedative-hypnotic component of propofol could be estimated by modern EEG variables (NT and BIS), whereas the analgesic component provided by remifentanil was not indicated. However, during conditions without surgical stimulation, neither NT nor BIS provided an adequate assessment of the depth of anesthesia when a remifentanil infusion was used. IMPLICATIONS: We investigated modern and classical electroencephalographic (EEG) variables during emergence from propofol/remifentanil anesthesia. Modern EEG variables indicate changes of infusion in propofol, but not in remifentanil. Thus, modern EEG variables did not provide an adequate assessment of depth of anesthesia when remifentanil was used.

Cowdria ruminantium antigens of around 15 kDa are potent inducers of IFN-gamma.

Cellular responses induced in two Creole goats by vaccination with killed Cowdria ruminantium (Cowdria) were confirmed by IFN-gamma production and interleukin-2 receptor (IL-2R) expression. Both CD4+ and CD8+ but not WC1+ T cells showed a substantial increase in cell surface expression of IL-2R molecules in response to whole Cowdria lysate. Cowdria (Welgevonden strain) proteins were fractionated using continuous-flow electrophoresis and tested for their ability to induce IFN-gamma production by PBMC collected three weeks after the first inoculation and one week after the booster injection. Pooled fractions of around 15, 22, and 24 kDa were found to induce significant IFN-gamma production in both vaccinated animals on one of the two occasions. Antigens of around 15 kDa induced substantially higher IFN-gamma production than any other fractions in both animals. These pilot experiments pave the way towards the identification of proteins/genes that have potential for the development of a recombinant vaccine against heartwater.

Low molecular weight proteins of Cowdria ruminantium (Welgevonden isolate) induce bovine CD4+-enriched T-cells to proliferate and produce interferon-gamma.

An important objective in vaccination strategies is to activate lymphocytes with particular effector functions. Cellular immunity and the type I cytokine IFN-gamma have been implicated in protective immunity to heartwater. Furthermore, low molecular weight proteins of Cowdria ruminantium have been shown to induce peripheral blood mononuclear cells to proliferate. To determine which lymphocyte subset responds when stimulated with fractionated C. ruminantium proteins, specific short-term lymphocyte cultures were established from cattle immunized with the Welgevonden isolate. Four cattle were immunized, two by infection and treatment and two with inactivated organisms. Cell surface phenotypic analysis of the cultures indicated that CD4+ lymphocytes were enriched over time. This coincided with increased antigen-specific proliferation and IFN-gamma production. Proteins of molecular weights 13-18kDa induced the CD4+-enriched T-cell cultures, derived from each of the animals, to proliferate and produce IFN-gamma. Although the two groups of cattle were immunized differently, their lymphocytes responded similarly. These results extend previous findings by identifying the responder cells as being predominantly IFN-gamma producing CD4+ lymphocytes. This cytokine has been implicated in immunity to the parasite. The low molecular weight proteins that induced CD4+ lymphocytes to proliferate and produce IFN-gamma are therefore likely to be important in protection against heartwater and may have a role in vaccine development.

Health care improvement and cost reduction opportunities in hypertensive Medicaid beneficiaries.

Hypertension and its complications are more frequent and occur about a decade earlier in life among high-risk groups, especially in the Southeast. Moreover, socioeconomic status is inversely related to hypertension and cardiovascular complications. Low-income, young and middle-aged adults living in the Southeast may be at especially high risk. Data on inpatient admissions among hypertensive Medicaid beneficiaries living in this region may provide insights on the burden of hypertension-related disease and on opportunities for successful intervention. A study of hospitalization rates and costs among 44,440 hypertensive Medicaid beneficiaries in South Carolina from 1993-1996 showed that 16,883 (38%) were continuously enrolled in Medicaid. Of this group, 63% were African American and 74% were women. Among the continuously enrolled patients, 7637, or about 45%, were hospitalized during the 4-year period. These 7637 individuals accounted for 20,698 hospital admissions, i.e., 2.7 admissions per person, over the 4-year interval. Nearly two thirds of the hospitalizations included a cardiovascular or renal diagnosis. Hospital claims paid reached nearly $90 million for the 7637 hypertensive Medicaid recipients during the 4-year period. Among patients discharged from the hospital with congestive heart failure, 33% filled a prescription for an angiotensin-converting enzyme inhibitor within 90 days; 13% of patients discharged with an acute myocardial infarction filled a prescription for a beta blocker within 90 days. The data confirm that hypertensive Medicaid beneficiaries in the Southeast are hospitalized at high rates. Cardiovascular and renal morbidity account for the majority of the inpatient admissions. The findings suggest that the application of evidence-based guidelines would improve health, avoid cost, and reduce racial disparities in health outcomes.

Identification of Cowdria ruminantium antigens that stimulate proliferation of lymphocytes from cattle immunized by infection and treatment or with inactivated organisms.

Cowdria ruminantium is an obligate intracellular pathogen that causes heartwater in ruminants. Several findings suggest that T cells play an important role in protection against the disease. In order to identify which proteins are involved in T-cell immunity, C. ruminantium proteins were fractionated by continuous-flow electrophoresis and tested for their ability to stimulate lymphocyte proliferation in vitro. C. ruminantium-infected endothelial cell lysates were fractionated at between 11 and 38 kDa and 50 and 168 kDa on 15 and 7% acrylamide gels, respectively. In an attempt to stimulate the natural infective process, peripheral blood mononuclear cells (PBMC) were obtained from two cattle rendered immune by infection and treatment and assayed in proliferation assays with fractionated proteins. In a parallel study, four cattle were immunized with inactivated C. ruminantium to determine whether their lymphocytes also responded to fractionated proteins. Proliferation assays after immunization by infection and treatment detected no C. ruminantium-specific proliferation in vitro after one vaccination. Proliferation was observed, however, between 1 and 4 weeks after challenge. This was followed by a period of no detectable response, after which the response reappeared. PBMC from animals immunized with inactivated organisms proliferated specifically in response to antigen soon after the first immunization. Only C. ruminantium proteins with low molecular masses of 11, 12, 14 to 17, and 19 to 23 kDa induced proliferative responses by lymphocytes from all six animals. These protein fractions may have potential as vaccine antigens.