Does the retention system influence the stability of implant-supported maxillary overdentures? A comparison with fixed and conventional dentures.

PURPOSE: The purpose of this in vitro study was to compare the stability of removable implant-supported maxillary overdentures with fixed complete dentures and conventional dentures. METHODS: Four types of complete dentures were tested: conventional complete dentures; overdentures retained by a male resilient attachment system; overdentures retained by a combination of clip bar and attachment system; and fixed complete dentures. Each group was placed in the posterior and anterior region and the stability was recorded by measuring the vertical displacement of the prosthesis. RESULTS: There was a difference in the vertical movement of the prosthesis according to the type of system. The results showed that the behavior of the overdenture retained by a combination of a clip bar and attachment system is comparable with the stabilization of an implant-retained fixed complete denture. CONCLUSIONS: Overdentures retained by a combination of a clip bar and attachment presented better stability and retention capacity under our experimental conditions, close to that of the positive control (fixed complete denture), with the advantages of removable overdentures.

Influence of recent altitude exposure on sea level sympathetic neural & hemodynamic responses to orthostasis.

Although it has been shown that muscle sympathetic nerve activity increases during high altitude exposure, mechanisms of sympathoexcitation and blood pressure control after return from altitude are not well described. We hypothesized that: (1) living for 12days at 4300m (Pikes Peak, Colorado) would result in increased muscle sympathetic nerve activity 24h after return to sea level; (2) post-Pikes Peak sympathetic neural and hemodynamic responses to orthostasis would be decreased due to a potential 'ceiling effect' on sympathetic activity; and (3) the magnitude of individual increases in sympathetic nerve activity post-Pikes Peak would be inversely related to baseline sympathetic nerve activity before traveling to altitude. Muscle sympathetic nerve activity, heart rate and blood pressure were measured in 9 healthy individuals (24±8years) in supine, 30° and 45° head-up tilt positions. Measurements were conducted twice at sea level, once before (pre-Pikes Peak) a 12day residence at 4300m, and once within 24h of return (post-Pikes Peak). Supine muscle sympathetic nerve activity was higher (post: 27±5 vs pre: 17±6bursts/min) upon return from altitude (p<0.05). Individual values for pre-Pikes Peak sympathetic activity were inversely related to post-altitude sympathoexcitation (r=-0.69, p<0.05). There were no differences in neural or cardiovascular responses to tilt between pre and post- Pikes Peak (p>0.05). We conclude that 12days' residence at 4300m causes a sustained sympathoexcitation which does not impair the ability of muscle sympathetic nerves to respond appropriately to orthostasis.

Approximation of head and neck cancer volumes in contrast enhanced CT.

BACKGROUND: Tumor volume may serve as a predictor of response to radiochemotherapy (RCT) in head and neck squamous cell carcinoma (HNSCC). Computer assisted tumor volumetry requires time-consuming slice-by-slice manual or semi-automated segmentation. We questioned how accurately primary tumor and suspect cervical lymph node (LN) volumes can be approximated by the maximum tumor diameters in three dimensions. METHODS: In contrast-enhanced diagnostic CT scans of 74 patients with incident advanced HNSCC, manual slice-by-slice segmentation volumetry of primary tumor, total- and largest suspect cervical LN served as the reference method. In the same scans, maximum orthogonal diameters were measured using the distance measurement tool in standard visualization software in axial and coronal sections. From these diameters, approximate volumes were calculated using the cubic and ellipsoid formula. A second segmentation volumetry was performed in contrast enhanced radiotherapy-planning CT scans obtained prior to primary concurrent RCT 24 days (+/- 13 days) following the initial diagnostic CT scans. Intraclass correlation coefficients and Bland-Altman analyses were used to compare results. RESULTS: Slice-by-slice manual segmentation volumetry of primary and LN volumes revealed a lognormal distribution and ranged from 0 to 86 ml and 0 to 129 ml, respectively. Volume approximations in diagnostic CT scans with the ellipsoid formula resulted in an -8 % underestimation of tumor volumes (95 % CI -14 % to -1 %; p = 0.022) and an -18 % underestimation of suspect cervical LN volumes (95 % CI -25 % to -12 %; p = 0.001). Inter rater intraclass correlation for primaries was 0.95 (95 % CI +0.92 to +0.97; p = 0.001), and intra rater intraclass correlation was 0.99 (95 % CI +0.98 to +0.99; p = 0.001). The cubic formula resulted in pronounced overestimation of primary and LN volumes. Primary tumor volumes obtained by the second segmentation volumetry in radiotherapy-planning CT scans obtained on average 24 days following the initial volumetry resulted in larger primary tumor volumes (mean bias +28 %, 95 % CI +14 % to +41 %; p = 0.001). Tumor volume increase correlated with time between the diagnostic and planning CTs (r = 0.24, p = 0.05) and was approximately 1 % per day. DISCUSSION: Ellipsoid approximations of tumor and lymph node volumes in HNSCC using maximum orthogonal diameters underestimates volumes based on segmentation in multiple slices. Due to time difference and safety margins, segmented volumes in radiotherapy-planning CT scans tend to be larger than in diagnostic CT scans. CONCLUSION: Ellipsoid approximations of tumor and lymph node volumes in HNSCC are easily available from diagnostic CT scans. Volume estimates are applicable over a wide range of tumor and LN sizes and may be useful in clinical decision-making and oncologic research.

Latex type I sensitization and allergy in children with atopic dermatitis. Evaluation of cross-reactivity to some foods.

Recent studies have demonstrated that allergy to natural rubber latex (NRL) is associated with cross-reactivity to certain foods. The aim of this study was to investigate the prevalence of NRL sensitization and allergy in children with atopic dermatitis (n=74). We also examined cross-reactions between latex and foods, and compared the frequency of suspected latex cross-reacting fruits in children with and without NRL-specific immunoglobulin E (IgE). Twelve of the 74 atopic children studied (16.2%; 95% confidence interval (CI), 8.7-26.6%) had circulating IgE antibodies to latex. These NRL-sensitized children were older and they showed significantly higher total IgE values (p<0.003) when compared with the group of children without NRL sensitization. Of the specific food IgE evaluations, 18.4% (93 out of 505) were positive, and 69.9% were observed in the group of children with latex-specific IgE, most frequently to potato, tomato, sweet pepper, and avocado. An isolated latex-specific IgE response without food-specific IgE was never observed. Exclusively in the latex-positive group, conformity with the report of allergic symptoms after ingestion of food and increased food-specific IgE was found. Twenty children without proven latex sensitization showed increased food-specific IgE, most frequently to potato, banana, and chestnut. Avocado-specific IgE was never determined in this patient group. No significant differences were detected concerning the sensitization to potato, banana, and kiwi between NRL-sensitized children and the group of 20 children without latex-specific IgE. The competitive CAP inhibition using sera from children with specific IgE to both latex and food showed different cross-reactivities between latex and the specific food. A close relationship existed between latex and avocado (median inhibition: 100%), whereas sensitization to latex and kiwi seemed to be independent in our study group (inhibition: <25%). In particular, for potato, cross-reactivity and co-sensitization existed. Our study demonstrated that children with atopic dermatitis are a high-risk group for latex sensitization. Increasing age, additional sensitization to ubiquitous inhaled allergens, and enhanced total serum IgE values seemed to be important variables for latex sensitization and further sensitization to the latex-associated foods. Cross-reactivity and, in some cases, co-sensitization to specific fruits and vegetables, were observed.

Class I endochitinase containing a hevein domain is the causative allergen in latex-associated avocado allergy.

BACKGROUND: In the medical literature immunoglobulin (Ig)E-mediated sensitization to avocado is rarely reported. On the other hand, more than 50% of subjects having IgE-mediated natural rubber latex allergy are sensitized to avocado fruit as demonstrated by skin-prick testing and/or specific IgE measurements and about 10-20% report hypersensitivity reactions after ingesting avocado. OBJECTIVE: The underlying pathomechanism of latex-associated avocado allergy is still unknown. The conserved hevein domain of the major latex allergen prohevein (Hev b 6.01) is a ubiquitous chitin-binding protein structure that can be found in several plant proteins and may be responsible for the observed cross-reactivity between latex and avocado fruit. METHODS: Chitin-binding avocado proteins (CBAPs) were isolated by affinity-chromatography and their IgE-binding characteristics were studied by immunoblotting using the sera from 15 avocado-sensitized latex patients. Inhibition experiments using isolated hevein and CBAPs as inhibitor solutions were performed to study the immunological cross-reactivity between both protein species and to assess the role of the CBAPs as mediators in latex-associated avocado allergy. RESULTS: In 80% of avocado-sensitized subjects (n = 15), IgE antibodies directed against a 31-kDa allergen were detected by immunoblotting. This IgE-binding protein was identified by protein sequencing to be a class I endochitinase containing a hevein domain at the N-terminus. Purified native and digested (using simulated gastric fluid) endochitinase were able to completely block all avocado-specific IgE antibodies in six out of seven avocado patients. CONCLUSIONS: Sensitization to endochitinase class I containing a hevein domain is the main underlying pathomechanism in latex-mediated avocado allergy.

Cloning, expression and characterization of the major latex allergen prohevein.

BACKGROUND: About 70-80% of latex allergic health care workers are sensitized to prohevein (Hev b 6.01), a 20 kDa cysteine-rich chitin-binding protein of Hevea latex. OBJECTIVE: This study reports on the bacterial cloning, expression and immunochemical characterization of rHev b 6.01. METHODS: Prohevein was expressed in the periplasmatic space of Escherichia coli as maltose binding protein (MBP) fusion protein and purified to homogeneity after factor Xa cleavage. The IgE binding capacity of both rHev b 6.01 and prohevein isolated from fresh Hevea latex was compared by immunoblotting experiments using sera of latex-allergic patients. The diagnostic value of rHev b 6.01 was analysed by enzyme allergosorbent test (EAST). RESULTS: Two different cDNA clones of rHev b 6.01 were established. The deduced amino acid sequence of both clones revealed two and three amino acid differences in the C-terminal domain of prohevein compared with the original database entry. Purified rHev b 6.01 bound with high affinity to chitin as its natural counterpart isolated from natural latex. In IgE-immunblotting using sera of affected subjects binding intensity to both proteins was comparable indicating a very high antigenic similarity. The diagnostic value of MBP-prohevein was tested in EAST using sera of 33 latex-allergic subjects. The in vitro test showed high sensitivity and specificity and proved the diagnostic value of uncleaved MBP-prohevein. CONCLUSIONS: The production of recombinant latex key allergens with defined quality like prohevein is a straightforward strategy for the development of standardized in vitro test systems.

Identification of hevein (Hev b 6.02) in Hevea latex as a major cross-reacting allergen with avocado fruit in patients with latex allergy.

BACKGROUND: Recent studies demonstrated that allergy to natural rubber latex is frequently associated with hypersensitivity to avocado fruit. The responsible cross-sensitizing allergen has not been identified. OBJECTIVE: The purpose of this study was to investigate the cross-reactivity of a latex major allergen, hevein, with avocado proteins. METHODS: Serum samples from 118 health care workers (HCWs) allergic to latex (HCW group) and 78 patients with spina bifida (SB) allergic to latex (SB group) were included in this study. Anti-hevein and anti-avocado IgE antibodies were measured by enzyme-linked allergosorbent assay. Cross-reactivity of hevein to avocado proteins was assessed by inhibition of the IgE binding in individual patients' sera containing IgE antibodies to both hevein and avocado. RESULTS: The prevalence of seropositive IgE antibodies to avocado was found to be strongly associated with the presence of hevein-specific IgE antibodies in subjects of both groups (P < .001). Sixty-seven of 91 (73%) subjects from the HCW group and all 19 subjects in the SB group with positive IgE antibodies to hevein also had elevated IgE values to avocado. Competitive RAST inhibition with 42 sera showed that IgE binding to avocado could be completely inhibited in 27 (64%) sera by preincubation with hevein. By contrast, the degrees of inhibition of IgE to hevein by avocado extract ranged from 0% to 36% (n = 16). These results indicate that sensitization to avocado in most patients allergic to latex is caused exclusively by IgE-binding epitopes present in hevein. Results of immunoblots and immunoblot inhibition with 11 serum samples confirmed that a 30-kd protein in avocado was the major IgE-binding component; the IgE-binding reactivity to this protein could be inhibited by hevein in all sera tested. CONCLUSION: Hevein is the major cross-reacting allergen with avocado in subjects with latex allergy.

Characterized allergens causing bakers' asthma.

Although airborne allergens in bakeries and confectioneries cause one of the most common forms of occupational asthma, namely, bakers' asthma, only a few of them are known in detail so far. Here we summarize current knowledge of bakery allergens and describe our own two-dimensional (2-D) immunoelectrophoresis studies of wheat-flour allergens as well as the allergenic baking enzyme Asp o 2. Out of approximately 700 soluble wheat polypeptides, 70 show IgE binding; the following wheat-flour allergens could be identified and characterized: members of the alpha-amylase inhibitor family (14-18 kDa), acyl-CoA oxidase (26 kDa), peroxidase (36 kDa), and fructose-bisphosphate aldolase (37 kDa). However, the great majority of the soluble wheat-flour allergens, mainly located in the 27-, 55-, and 70-kDa areas of the 2-D immunoblots with pI values of 5.8-6.8, 5.9-6.5, and 5.5-6.1, respectively, are not known at present. Asp o 2, to which approximately 25% of all bakers with respiratory symptoms are sensitized, is a well-characterized starch-cleaving enzyme. We conclude that great effort is still needed to describe all major wheat-flour allergens. As shown by Asp o 2, knowledge of the causative allergens and their characteristics enables us to initiate very effective preventive measures such as the introduction of granulated allergenic products.

Baker's asthma due to the enzyme xylanase -- a new occupational allergen.

The asthmatic baker showed IgE-mediated sensitization to xylanase of Aspergillus niger used as a baking additive. Inhalative challenge with approximately 0.5 microg of the enzyme resulted in an immediate-type asthmatic reaction. This case, as well as a preliminary screening of symptomatic bakers, shows that xylanase is a further relevant type I-sensitizer in the baking industry.

On the allergenicity of Hev b 1 among health care workers and patients with spina bifida allergic to natural rubber latex.

BACKGROUND: Recent studies have caused much controversy about the prevalence of IgE antibodies to Hev b 1 among health care workers (HCWs) and patients with spina bifida (SB) who are allergic to latex. This investigation was carried out to verify the results reported. METHOD: Serum samples from 140 patients with SB as well as from 105 HCWs allergic to latex were tested by enzyme allergosorbest test (EAST) and EAST-inhibition assay to evaluate the rate and degree of sensitization to highly purified Hev b 1. RESULTS: Eighty-one percent of patients with SB who were allergic to latex had IgE antibodies against Hev b 1. The prevalence of anti-Hev b 1 antibodies among HCWs allergic to latex was 52.3%. In 15 of 33 serum samples from patients with SB that were randomly tested, the IgE binding to commercial latex allergens could be completely inhibited by Hev b 1; in only six cases was the maximum inhibition of IgE binding to latex by Hev b 1 less than 50%. Testing two monoclonal anti-Hev b 1 antibodies with extracts of five brands of latex gloves revealed a predominant presence of Hev b 1 protein as a monomer or its aggregates. Molecular analysis of human leukocyte antigen-D region genes DRB and DQB1 suggested no statistically significant correlation between the human leukocyte antigen alleles tested and IgE responsiveness to Hev b 1. CONCLUSIONS: Our results indicate that Hev b 1 not only makes significant contributions to the IgE binding to latex, but it is also the unique sensitizer in about 45% of patients with SB who are allergic to latex.

Characterization and identification of latex allergens by two-dimensional electrophoresis and protein microsequencing.

BACKGROUND: Proteins of natural rubber latex cause IgE-mediated sensitization in 3% to 18% of health care workers and in up to 50% of patients with spina bifida. OBJECTIVE: This study was aimed at the generation of a comprehensive latex protein database by two-dimensional electrophoresis (2-DE). METHODS: Proteins extracted from fresh Hevea brasiliensis latex were separated by 2-DE. IgE-reactive proteins were analyzed by immunoblotting with sera of health care workers with latex allergy. Protein microsequencing and monoclonal antibodies were used to identify the latex allergens. RESULTS: The latex C-serum 2-DE map was very complex and exhibited about 200 distinct polypeptides. The proteins eluted from the latex particles consisted primarily of two groups of acidic proteins located in the 8 to 14 kd and 22 to 24 kd areas of the 2-DE map. Major IgE-reactivity was detected with C-serum proteins in the 56, 45, 30, 20, 14, and <6.5 kd areas of the immunoblots. The 8 to 14 kd particle proteins exhibited distinct IgE reactivity, whereas the 22 to 24 kd proteins were not stained. Seven of the soluble IgE-reactive protein spots showed high homology with enolase, superoxide dismutase, triosephosphate isomerase, proteasome subunit, and chitinase and represent previously undescribed latex allergens; whereas nine protein spots corresponded to known latex allergens, namely prohevein, hevein, prohevein C-domain, and hevamine. As identified by monoclonal antibodies, the IgE-reactive latex particle proteins mainly represent the allergenic rubber elongation factor. CONCLUSIONS: Two-dimensional electrophoresis, followed by immunoblotting and protein microsequencing, can rapidly identify a large number of IgE-binding latex proteins. The 2-DE latex maps generated will provide valuable information for the development of strategies to isolate the relevant latex allergens. Because the novel latex allergens are common plant enzymes, they may also act as cross-reacting proteins in various foods.

Isolation and identification of hevein as a major IgE-binding polypeptide in Hevea latex.

BACKGROUND: Polypeptides in Hevea latex are known as the major cause of latex type I sensitivities. So far, only a few of them have been characterized. METHODS: Proteins with a molecular weight lower than 10 kd in fresh Hevea latex were separated by ultrafiltration and further characterized by liquid chromatography on-line-coupled electrospray mass spectrometry. Hevein in this fraction was then purified by preparative reverse-phase high-performance liquid chromatography and characterized by matrix-assisted laser desorption ionization mass spectrometry and protein sequencing. Skin prick tests, enzyme-linked allergosorbent tests, and inhibition immunoblotting were performed to show the allergenicity of the purified hevein. RESULTS: Hevein, a 4.7 kd polypeptide, is the predominant component in the fraction with latex proteins of smaller than 10 kd. Specific IgE antibodies to hevein were detected by enzyme-linked allergosorbent test in 48 of 64 (75%) sera from health care workers allergic to latex and in three of 11 (27%) sera from patients with spina bifida and hypersensitivity reactions to latex. Inhibition immunoblotting demonstrated that the preincubation of 14 sera and a serum pool from patients allergic to latex with purified hevein completely inhibited IgE binding to the 20 kd protein, which has been recently reported to be a major allergen in latex (prohevein). Skin prick testing showed a positive reaction to hevein in 17 of 21 (81%) patients with latex allergy. CONCLUSIONS: The results clearly demonstrate that hevein is an important latex allergen, and the IgE-binding capacity of prohevein in latex is mostly attributed to hevein, the N-terminal domain of prohevein.

[Latex allergens: review of current knowledge]. / Latexallergene: Ubersicht zum gegenwärtigen Kenntnisstand.

Both health care workers and spina bifida patients are at risk to develop type I latex allergy since allergenic proteins of natural rubber latex are present in a variety of latex products. Natural latex contains more than 250 polypeptides and approximately 60 of them show IgE-binding characteristics. A multitude of these latex allergens has been identified, and their sensitization potency for both risk groups has been determined. While hevein (Hev b 6.02) is the major allergen in latex-allergic health care workers, 80% of latex sensitized-spina bifida children have IgE antibodies to the "rubber elongation factor" (Hev b 1). Almost all relevant latex allergens have been identified in natural latex products: however, no data on the allergen profiles of individual latex products exist. The knowledge of the major latex allergens enables improved diagnosis and to monitor the success of prevention strategies for decreasing the high prevalence of latex allergies.

Latex allergen database.

Two-dimensional (2-D) electrophoresis followed by immunoblotting and N-terminal protein microsequencing were used to characterize and identify the IgE-reactive proteins of Hevea latex that are the main cause of the latex type I allergy affecting especially health care workers and spina bifida children. This approach generated a comprehensive latex allergen database, which facilitated the integration of most of the latex allergen data presented in the literature. The major latex allergens Hev b 1, Hev b 3, Hev b 6 and Hev b 7 have been localized on our 2-D maps. Moreover, we were able to identify six previously undescribed IgE-binding latex proteins, namely enolase, superoxide dismutase, proteasome subunit C5, malate dehydrogenase, triosephosphate isomerase and endochitinase. The generated latex 2-D maps will provide valuable information to develop strategies for the isolation of the novel IgE binding proteins in order to study the frequency of sensitization among both risk groups. Detailed knowledge of all proteins involved in latex allergy will allow better diagnosis of latex allergy and to monitor the success of prevention strategies that are needed to reduce the high prevalence of latex allergy among both risk groups.

Cross-reactivity between natural rubber latex and food allergens.

Immediate-type hypersensitivity to latex is a growing problem, especially among health care workers (HCWs) and patients requiring long-term catheterization and multiple operations. The responsible allergens are latex proteins, which are found in raw latex, as well as in various latex-containing products. More than 200 polypeptides can be discerned in latex sap and of these, 60 proteins showed reactivity with IgE antibodies from patients with latex allergy. Several of these proteins have been characterized at the molecular level and their role in latex allergy has been elucidated. Latex allergy is often associated with hypersensitivity to certain fruits and vegetables like avocado, kiwi, banana, sweet pepper, and tomato. Several case reports demonstrate a potential for serious allergic reactions to foods in latex allergic patients. Nevertheless, comprehensive studies on the clinical significance and relevance of this co-sensitization are missing. Although some of the latex allergens are ubiquitous plant proteins or share structural features with plant proteins, the molecular bases of these cross-reactivities have not yet been clarified.

EAST and CAP specificity for the evaluation of IgE and IgG antibodies to diisocyanate-HSA conjugates.

Sera of 54 symptomatic workers showing sensitization to isocyanate-human serum albumin (HSA) conjugates were subjected to parallel enzyme allergosorbent test (EAST) and CAP measurements to determine IgE antibodies to diphenyl-methane diisocyanate-HSA, toluene diisocyanate-HSA and hexamethylene diisocyanate-HSA. Results of both methods correlated rather well with each other. In comparison to the EAST results, the CAP values were twice as high, and 4, 17 and 13% more frequently positive findings were obtained with the three different antigens. Autoinhibition performed with both methods proved the specificity of IgE binding in 92% of sera in EAST and in 89% of sera in CAP if values of > or = 0.35 kU/l were considered. The total IgE level in sera influenced the antibody results. Four of 20 sera studied by autoinhibition had a total IgE of > 700 kU/l, and two of them did not show significant autoinhibition with all conjugates by CAP and one serum by EAST. In addition, three of these sera showed an elevated binding to control HSA only (0.31-0.5 kU/l), and two revealed only a slightly increased IgE binding when compared with the HSA control (ratio of isocyanate-HSA to HSA, < 2). Only 2 of the 16 sera with a total IgE level of < 700 kU/l yielded a noninhibitory positive CAP result, whereas all positive EAST values of these sera could be significantly blocked by autoinhibition. Therefore, we suggest regarding EAST and CAP IgE results to isocyanate-HSA as positive if they exceed HSA control by 100% and are above 0.35 kU/l. Weak positive CAP results (< or = kU/l), especially of sera with total IgE > 700 kU/l, should by confirmed by inhibition experiments. Twelve of 40 symptomatic isocyanate workers exhibited borderline or weakly increased IgG values for diisocyanate-HSA conjugates in the CAP system and IgG-EAST. HSA tested in EAST as a reference showed nearly the same results as the isocyanate-HSA conjugates. In the 23 inhibition experiments, IgG-binding specificity was not confirmed. These findings imply IgG measurement to be of no diagnostic value in isocyanate-induced airway disorders.

Increased radiosensitivity by a combination of 9-cis-retinoic acid and interferon-y in breast cancer cells.

Interferons (IFNs) and retinoic acid (RA) are known to possess antiproliferative effects in various human cancer cell lines, including squamous cervix carcinoma and breast cancer cell lines. Frequently synergistic effects could be observed by the combination of both, and in clinical trials high response rates could be achieved by IFN-alpha in combination with 13-cis-RA in patients with squamous carcinoma of the uterine cervix. Since radiation-potentiating effects of IFNs and RA were described, we evaluated the additional impact of irradiation on three human breast cancer cell lines and investigated the antiproliferative effects of single, double, or triple treatments with IFN-gamma, 9-cis-RA, and irradiation. Antiproliferative effects were observed in all cell lines by any single treatment. When combining IFN-gamma with 9-cis-RA, synergism could be observed in all experiments. The combination of either IFN-gamma or 9-cis-RA with irradiation resulted mostly in additive effects. Irradiation contributed additive or further synergistic effects to the already synergistic effects of the combination of these two drugs. Thus synergism of IFN-gamma and 9-cis-RA always at least persisted fully. These results suggest that a regimen of IFN, RA, and radiotherapy (RT) might be a promising combination in the therapy of solid tumors, where RT is part of the conventional treatment.

Compression characteristics of CPR manikins.

We evaluated the force-depth compression characteristics of 8 different CPR manikins during mechanical cardiopulmonary resuscitation by a thumper. The force required to compress the manikin's thorax of 1, 2, 3, 4 and 5 cm was measured. It ranged between 6.3 and 14 kp at a depth of 1 cm, 11.6-30 kp at 2 cm, 17-38 kp at 3 cm, 22.5-54 kp at 4 cm and 28.5-69 kp at 5 cm. The manikins with a spring in the thorax (Ambu Man, Ambu MultiMan, Dräger CPR-Max, Laerdal Resusci Anne) as well as one without (Ambu CPR Pal) showed a rather linear relationship between depth and force required to compress the chest. Ambu Man, set at 'High', Laerdal Resusci Anne and Dräger CPR-Max revealed a slight increase in resistance, whereas 2 manikins without a spring (Laerdal Little Anne, Laerdal Family Trainer) and 1 manikin with a plastic spring-like construction (Actar 911) exhibited less resistance with increasing depth. According to our results, the manikins are not uniform in their compression characteristics; some become nonlinear when 3 cm of compression is exceeded. For correct CPR it is of utmost importance that the CPR trainee learns to compress in a sufficiently strong manner, but simultaneously to avoid an exceedingly high depth of compression irrespective of the thorax resistance. In order to prepare the CPR student for the varying chest resistances of the human body, we recommend to train CPR on manikins with different chest resistances.