Survival rates, patient satisfaction, and prosthetic complications of implant fixed complete dental prostheses: a 12-month prospective study

PURPOSE

To determine the survival rate, incidence of prosthetic complications, and patient satisfaction of implant fixed complete dental prostheses (IFCDPs) after a mean observation period of 1.4 years.

MATERIALS AND METHODS

Twenty-eight (28) eligible participants were recruited according to specific inclusion and exclusion criteria. The definitive metal-acrylic resin IFCDPs consisted of titanium bars veneered with acrylic resin and acrylic denture teeth. Prosthodontic complications, divided into major and minor, were monitored. Parameters such as gender, jaw location, bruxism, and occlusal scheme were evaluated. Moreover, a questionnaire was administered throughout the study to assess patient satisfaction. Poisson regression as well as repeated measures ANOVA were used for statistical analysis.

RESULTS

Fourteen (14) males and 14 females were enrolled and followed-up at 3, 6, and 12 months. All IFCDPs survived (100% survival rate). The most frequent minor complication was the loss of material used to close the screw access hole (20% out of total complications). The most frequent major complication was chipping of the acrylic denture teeth (77.14% out of total complications). Gender (p = 0.008) and bruxism (p = 0.030) were significant predictors for the total major complications (major wear and major chipping) while occlusal scheme was a significant predictor for major chipping events (p = 0.030).

CONCLUSIONS

While IFCDPs demonstrated high prosthetic survival rates, they also exhibited a high number of chipping events of the acrylic veneering material, especially in males, bruxers, and individuals with canine guidance occlusion. However, the occurrence of these prosthetic complications did not negatively affect patient satisfaction.

Clinical outcomes of full-arch immediate fixed prostheses supported by two axial and two tilted implants: A retrospective cohort study with 12-15 years of follow-up

PURPOSE

To retrospectively assess clinical and radiographic outcomes of immediately loaded full-arch fixed prostheses supported by axial and tilted implants up to 15 years of function.

MATERIALS AND METHODS

Patients with one completely edentulous arch received an immediate full-arch fixed prosthesis supported by two anterior axial and two posterior tilted implants. Definitive prosthesis consisting of a CAD-CAM titanium framework and acrylic teeth was delivered 6 months later. Patients were regularly followed to assess clinical parameters and marginal bone level (MBL) change. Multilevel regression analysis was performed to investigate factors affecting implant failure and MBL.

RESULTS

Six hundred ninety-two implants were placed in 72 maxillae and 101 mandibles. Seven maxillary implants (5 axial and 2 tilted) in 6 patients and 12 mandibular implants (6 axial and 6 tilted) in 5 patients failed. 15-year cumulative implant survival was 97.51% and 96.91% in maxilla and mandible, respectively (p = .64). After 10 years, the difference in MBL between axial and tilted implants was not significant in the maxilla (p = .47, 65 patients), while it was in the mandible (p < .001, 80 patients). Significant higher bone loss was reported in the mandible at both 5- and 10-year follow-up (p < .001 and p = .004, respectively). Mixed-effect multilevel linear regression evidenced a correlation between arch and bone loss at 5- and 10-year follow-up, while no correlation was found with age, gender, smoking, diabetes, and history of periodontal disease.

CONCLUSION

This long-term study suggests that the present technique can be considered a viable treatment modality for the immediate rehabilitation of both maxilla and mandible.

Copy-paste concept: Full digital approach in the management of gingival emergence profiles

OBJECTIVE

Obtaining a perfect integration of a prosthetic rehabilitation on natural teeth and implantys in the esthetic zone requires a deep knowledge of the biological processes and a clear understanding of the characteristics of the restorative materials. Once the soft tissue profile has been created with the placement of a temporary prosthesis, the ability to accurately transfer information about the tissue profile and the contour of the restoration for the fabrication of the definitive crowns can be challenging.

CLINICAL SIGNIFICANCE

This paper illustrate the copy paste full digital workflow, a simple protocol that allows to create definitive restorations by making an exact copy of the temporary prosthesis that has been placed in function in the patient's mouth.

Complete Digital Workflow for Prosthesis Prototype Fabrication with the Double Digital Scanning (DDS) Technique: A Prospective Study on 16 Edentulous Maxillae

PURPOSE

To assess the accuracy of fit of milled prosthesis prototypes for completely edentulous patients using a digital workflow.

MATERIALS AND METHODS

Sixteen patients received intraoral full-arch digital scans with the double digital scanning (DDS) technique and the generated standard tessellation language (STL) files were superimposed and imported into computer-aided design software (Exocad DentalCAD, exocad GmbH, Darmstadt, Germany) for design. After the design, each master STL file was used for computer-aided manufacturing of the prosthesis prototypes through a complete digital workflow. The primary outcome was the accuracy of fit assessment of the digitally fabricated prototypes on verified patient master stone casts. Two blinded clinicians tested the accuracy of fit of the milled prosthesis prototypes on the verified master stone casts utilizing the screw-resistance test and direct observation.

RESULTS

Out of the 16 digitally fabricated prototypes from intraoral full-arch digital scans, all 16 presented with an accurate fit on verified master stone casts.

CONCLUSIONS

Digitally fabricated full-arch prosthesis prototypes can be generated with a complete digital workflow leading to clinically acceptable fit.

Insertion and removal torque of dental implants placed using different drilling protocols: An experimental study on artificial bone substitutes

PURPOSE

The aim of this in vitro study was to measure the insertion and removal torque values of dental implant replicas inserted into artificial bone blocks using different surgical burs and drilling protocols.

MATERIALS AND METHODS

Four types of artificial, polyurethane bone blocks were used with different thicknesses (1 and 2 mm) and densities (soft-1 mm, soft-2 mm, dense-1 mm, and dense-2 mm) of the simulated cortical and cancellous bone, respectively. Each bone construct was drilled with Straumann and Densah drills in both clockwise and counterclockwise directions for a total of 16 experimental conditions. For every scenario, 38 implant replicas were inserted and then removed after 1 min. Outcomes of interest were the insertion and removal torque values which were recorded by a torque meter. ANOVA and Tukey HSD tests were used to assess differences across each combination of drill, direction, and bone type.

RESULTS

Densah counterclockwise registered statistically greater values for both insertion and removal torque, followed by Densah clockwise, Straumann counterclockwise, and Straumann clockwise. Increasing insertion and removal torque values were progressively reported for bone type (soft-1 mm, dense-1 mm, soft-2 mm, and dense-2 mm). The mean values of insertion and removal torque were significantly different (p < 0.05) across the four bone types, different burs, and with the two drilling modalities.

CONCLUSIONS

Densah bur resulted in significantly greater values of torque compared to the Straumann drills for all the experimental conditions. The thickness of the cortical layer and the counterclockwise drilling direction play a significant role in determining the implant insertion torque.

Outcomes of Fixed Full-Arch Rehabilitations Supported by Tilted and Axially Placed Implants: A Systematic Review and Meta-Analysis

PURPOSE

To evaluate the performance of fixed complete dental prostheses supported by axial and tilted implants after at least 3 years of follow-up.

MATERIALS AND METHODS

An electronic search plus a hand search up to April 2021 was undertaken. Clinical studies were selected using specific inclusion criteria, independent of the study design. The main outcomes were cumulative implant survival rate, marginal bone level changes, and complications, after ≥ 3 years of follow-up. The difference in outcomes between axial and tilted implants and between the maxilla and mandible was evaluated using meta-analysis and the Mantel-Cox test.

RESULTS

Out of 824 articles retrieved, 24 were included. In total, 2,637 patients were rehabilitated with 2,735 full prostheses (1,464 maxillary, 1,271 mandibular), supported by 5,594 and 5,611 tilted and axial implants, respectively. In a range between 3 and 18 years of follow-up, 274 implants failed. The cumulative implant survival rate was 93.91% and 99.31% for implants and prostheses, respectively. The mean marginal bone level change was moderate, exceeding 2 mm in only two studies. Marginal bone loss was significantly lower around axial compared with tilted implants (P < .0001), whereas it was not affected by arch (maxilla vs mandible; P = .17).

CONCLUSION

Fixed complete dental prostheses supported by tilted and axially placed implants represent a predictable option for the rehabilitation of edentulous arches. Further randomized trials are needed to determine the efficacy of this surgical approach and the remodeling pattern of marginal bone in the long term.

Clinical outcomes and biological and mechanical complications of immediate fixed prostheses supported by zygomatic implants: A retrospective analysis from a prospective clinical study with up to 11 years of follow-up

BACKGROUND

Zygomatic implants alone or in combination with conventional implants have been used for severe atrophic maxillary arches. Long-term outcomes of extramaxillary technique need validations.

PURPOSE

To retrospectively assess the clinical outcomes and the prevalence of surgical, biological, and prosthetic complications of implant-fixed complete dental prostheses (IFCDPs) supported by zygomatic implants up to 11 years of follow-up.

MATERIALS AND METHODS

Dental records of 34 subjects treated between October 2008 and June 2019 were reviewed. Patients received an immediate fixed full-arch prosthesis supported solely by zygomatic implants or by a combination of zygomatic and conventional implants.

RESULTS

A total of 90 zygomatic implants and 53 standard implants were placed. Up to 11 years of follow-up, two conventional implants were lost, leading to 96.2% success rate for conventional implants and 100% for zygomatic implants. Marginal bone loss for conventional implants averaged 0.85 ± 0.17 mm after the first year and 1.36 ± 0.12 mm after 10 years, resulting in full implant success. No prosthesis was lost. The main surgical complication was the perforations of the Schneiderian membrane, occurring in five patients and in seven sinus cavities. Considering the biological complications, mucositis for standard and zygomatic implants ranged between 21%-35% and 26%-40%, respectively. No peri-implantitis were reported. Soft tissue hypertrophy ranged between 1.8% and 30% for conventional implants and 1.1%-35% for zygomatic implants. Inflammation under the prosthesis ranged between 33% and 50%. For the mechanical complications, abutment loosening was recorded in 5.8% of cases (two patients), tooth debonding and fracture of the prosthesis happened in five subjects (14.7%), and loosening of the prosthetic screws was reported in one patient (2.9%).

CONCLUSIONS

Immediate rehabilitation of the severely atrophic maxilla with zygomatic implants alone or in combination with standard implants could be considered a viable treatment modality.

Experimental analysis of the influence of cortical bone layers and bone quantity on implant primary stability

The systematic analysis of parameters impacting implant primary stability is difficult to achieve with human cadavers or animal models, particularly for complex trans-sinus procedures to determine the effects of cortical layers and bone engagement on implant stability before and after a simulated load in vitro. Solid rigid polyurethane blocks, partially intersected by an 8-mm-thick space, were created to imitate tri-cortical situations, the presence of the sinus cavity, and the posterior maxilla with different degrees of bone atrophy. Implants were inserted through the cavity at an angle of 30˚ (scenarios 1 and 2) to imitate the clinical protocol. Controls simulating uni-cortical anchorage and no sinus cavity were also included (controls 1 and 2). Four parameters were measured: peak insertion torque, insertion work, resistance to lateral bending loads and extraction torque. Scenarios 1 and 2 displayed similar peak insertion torque to control 2, where all three groups anchored equal amounts of bone surrogate. The distribution of surrogate bone in contact with trans-cavity implants influenced both extraction torque and the degree of lateral bending. Sufficient peak insertion torque can be attained with a trans-sinus tricortical implant anchorage providing sufficient apical and coronal bone is engaged.

Survival rates and prosthetic complications of implant fixed complete dental prostheses: An up to 5-year retrospective study

STATEMENT OF PROBLEM

Implant fixed complete dental prostheses (IFCDPs) are widely used in the rehabilitation of completely edentulous patients, yet limited information is available on the relationship between prosthetic complications and patient-associated and prosthesis-associated risk factors.

PURPOSE

The purpose of this retrospective study was to assess the prosthetic complication and survival rates of IFCDPs after a mean observational period of 3.5 years.

MATERIAL AND METHODS

Eligible participants were identified by an electronic health record review. The study consisted of a review of the dental record and a single-visit study appointment when a comprehensive examination was performed, including a review of the medical and dental history, clinical and radiographic examination, intraoral photographs, patient satisfaction questionnaire, and occlusal analysis. Prosthodontic parameters and risk factors were assessed, including time with the prosthesis in place, bruxism, occlusal device use, prosthesis material, number of implants, cantilever length, and mode of prosthesis retention. Association between these prosthodontic parameters and risk factors and the observed prosthetic complications was assessed.

RESULTS

A total of 37 participants (mean age 62.35 ±10.39 years) with 48 IFCDPs were included. Thirty-eight prostheses were metal-acrylic resin (MR group), whereas 10 were metal-ceramic (MC group). Five of the 48 prostheses failed during the follow-up period, a cumulative prosthesis survival rate of 88%. Minor complications were more frequent than major complications. The most frequent minor complication was loss of screw access hole material (5.18%/year), whereas the most frequently observed major complication was major wear of the prosthetic material (5.85%/year). A significant association was found between not wearing an occlusal device and minor chipping, loss of access hole material, and framework fracture. Minor chipping was significantly associated with bruxism, whereas the opposing dentition significantly affected the total number of prosthetic complications.

CONCLUSIONS

High survival rates were observed with both MR and MC IFCDPs. No significant difference was found between MR and MC groups in terms of patient satisfaction, as well as total number of prosthetic complications.

Immediate full-arch rehabilitation of the severely atrophic maxilla supported by zygomatic implants: a prospective clinical study with minimum follow-up of 6 years

The aim of this study was to evaluate the outcomes of immediate full-arch prostheses supported by zygomatic implants alone or in combination with standard fixtures after a minimum of 6 years of loading. From October 2008 to April 2010, 15 patients with severely atrophic maxillae were treated using four zygomatic implants or two zygomatic implants in conjunction with two conventional fixtures. All subjects received a fixed screw-retained prosthesis within 3hours of surgery, while the final restoration was delivered after 6 months. Follow-up examinations were scheduled to evaluate zygomatic implant survival, conventional dental implant success, prosthetic success, plaque and bleeding scores, marginal bone loss for conventional dental implants, and patient satisfaction. Forty-two zygomatic fixtures and 18 standard implants were placed. Patients were followed up for a minimum of 79 months (range 79-97 months, average 90.61 months). No implant was lost, leading to implant and prosthetic survival rates of 100%. Bone loss for conventional implants averaged 1.39±0.10mm after 6 years of function, leading to a 100% implant success rate. High levels of patient satisfaction were recorded. These medium-term results indicate that immediate full-arch rehabilitation supported by zygomatic implants could be considered a viable treatment modality for the severely atrophic maxilla.

Immediate fixed rehabilitation of the edentulous maxilla: a prospective clinical and radiological study after 3 years of loading

PURPOSE

The aim of this study was to prospectively evaluate the clinical and radiographic outcomes of immediate full-arch fixed maxillary prosthesis supported by two axial and four tilted implants after 3 years of loading.

MATERIALS AND METHODS

Thirty-two patients with atrophic maxilla were consecutively enrolled and treated. Each patient received a fixed full-arch maxillary rehabilitation supported by four tilted implants that engaged the posterior and the anterior sinus walls and two axial anterior implants. A total of 192 implants (30 Brånemark System MK IV and 162 NobelSpeedy Groovy, Nobel Biocare AB, Göteborg, Sweden) were inserted and immediately loaded. The definitive restorations were placed 6 months later, and follow-up visits were scheduled every 6 months. During follow-ups, marginal bone loss (MBL), plaque and bleeding scores, and patient's satisfaction were recorded.

RESULTS

All patients reached at least 3-year follow-up examination (range 36-78, average 55.53 months). Two tilted implants failed before delivering the definitive restoration, resulting in a cumulative survival rate of 98.96%. All final prostheses were stable and functional, resulting in a cumulative survival and success rate of 100%. At the 3-year follow-up there was no significant difference in MBL between axial (1.55 ± 0.31 mm) and tilted implants (1.46 ± 0.19 mm) (p = .05). Plaque and bleeding scores decreased over time, while patient's satisfaction in both aesthetics and function increased.

CONCLUSIONS

Implants placement with this configuration could be considered a predictable and cost- and time-effective alternative approach for the immediate restoration of the edentulous maxilla, avoiding bone grafting procedures, even with a medium-term follow-up.

Marginal accuracy of three implant-ceramic abutment configurations

PURPOSE

Microgaps at the implant-abutment interface allow for microbial colonization, which can lead to peri-implant tissue inflammation. This study sought to determine the marginal accuracy of three different implant-zirconium oxide (zirconia) abutment configurations and one implant?titanium abutment configuration.

MATERIALS AND METHODS

Three combinations of implants with custom-made zirconia abutments were analyzed (n = 5/group): NobelProcera abutments/titanium inserts on Replace Select Tapered TiUnite implants (Nobel Biocare) (NP); Encode abutments/NanoTite Tapered Certain implants (Biomet 3i) (B3i); Astra Tech Dental Atlantis abutments/Biomet 3i NanoTite Tapered Certain implants (At). Five custom-made Encode titanium abutments/NanoTite Tapered Certain implants (Ti) were used as a control group. All abutments were fabricated with computer-aided design/computer-assisted manufacture. One-hundred twenty vertical gap measurements were made per sample using scanning electron microscopy (15 scans x 4 aspects of each specimen [buccal, mesial, palatal, distal] x 2 measurements). Analysis of variance was used to compare the marginal fit values among the four groups, the specimens within each group, and the four aspects of each specimen.

RESULTS

Mean (± standard deviation) gap values were 8.4 ± 5.6 Μm (NP), 5.7 ± 1.9 Μm (B3i), 11.8 ± 2.6 Μm (At), and 1.6 ± 0.5 Μm (Ti). A significant difference was found between B3i and At. No difference resulted between NP with the other two groups. Gap values were significantly smaller for Ti relative to all zirconia systems. For each ceramic abutment configuration, the fit was significantly different among the five specimens. For 12 of the 15 ceramic abutment specimens, gap values sorted by aspect were significantly different.

CONCLUSIONS

The implant?titanium abutment connection showed significantly better fit than all implant?zirconia abutment configurations, which demonstrated mean gaps that were approximately three to seven times larger than those in the titanium abutment system.

Immediate rehabilitation of the edentulous maxilla: preliminary results of a single-cohort prospective study

PURPOSE

This article reports preliminary results of a single-cohort prospective study that sought to evaluate a new surgical protocol for the immediate rehabilitation of edentulous maxilla without using bone grafting.

MATERIALS AND METHODS

Twenty consecutive patients in need of a full-arch maxillary rehabilitation were included in the study. Each patient received four tilted implants that engaged the posterior and the anterior sinus wall and two axial implants in the anterior maxilla. A total of 120 implants (30 Branemark System MK IV and 90 NobelSpeedy Groovy) was inserted. Acrylic resin provisional prostheses were delivered within 4 hours of implant placement, and definitive restorations were placed 4 to 6 months later. Follow-up visits were scheduled every 6 months for the first 2 years and yearly thereafter. At each follow-up appointment, plaque and bleeding indexes were scored, periapical radiographs were obtained to assess marginal bone level changes, and patient satisfaction was recorded by means of a questionnaire.

RESULTS

The follow-up ranged between 18 and 42 months (average, 27.2 months). No implants failed. All prostheses were stable and functional. No adverse events occurred. At 1 year, mean marginal bone loss around axial and tilted implants was similar: 0.8 mm for axial implants (SD 0.4, n = 30) and 0.9 mm for tilted implants (SD 0.5 mm, n = 60) (P > .05). Plaque and bleeding scores decreased over time, and patient satisfaction with both esthetics and function increased.

CONCLUSIONS

This technique can be considered a viable treatment modality for the immediate rehabilitation of the edentulous maxilla, as it provides optimal support in the posterior region, minimizes distal cantilevers, and avoids bone grafting or sinus augmentation.

Comparison of tilted versus nontilted implant-supported prosthetic designs for the restoration of the edentuous mandible: a biomechanical study

PURPOSE

The purpose of the study was to evaluate, using finite element analysis, the stress patterns induced in cortical bone by three distinct implant-supported prosthetic designs.

MATERIALS AND METHODS

The first two models consisted of a prosthesis supported by four implants, the distal two of which were tilted, with different cantilever lengths (5 mm and 15 mm). The third design consisted of a prosthesis supported by five conventionally placed implants and a 15-mm cantilever.

RESULTS

In the tilted model with 5-mm cantilever and in the nontilted model, the maximum value of compressive stress (-18 MPa) was found near the cervical area of the distal implant. Higher values for compressive stress were predicted near the cervical area of the distal implant in the tilted model with a 15-mm cantilever, as compared to the tilted model with the 5-mm cantilever. For the tilted model with the 5-mm cantilever, peak values of tensile stress were predicted near the cervical area of both the distal (1.25 MPa) and the mesial implants (2.5 MPa). For the nontilted model, the peak value was found near the cervical area of the in-between implant (5 MPa). For the tilted model with 15-mm cantilever, tensile stress values were higher than in the tilted model with 5-mm cantilever.

CONCLUSIONS

No significant difference in stress patterns between the tilted 5-mm and the nontilted 15-mm configuration was predicted. The tilted configuration with a 15-mm cantilever was found to induce higher stress values than the tilted configuration with a 5-mm cantilever.

A finite element analysis of tilted versus nontilted implant configurations in the edentulous maxilla

The aim of this study was to evaluate stress patterns at the bone-implant interface of tilted versus nontilted implant configurations in edentulous maxillae using finite element models of two tilted and one nontilted configuration. Analysis predicted the maximum absolute value of principal compressive stress near the cervical area of the distal implant for all models. The tilted configurations showed a lower absolute value of compressive stress compared with the nontilted, indicating a possible biomechanical advantage in reducing stresses at the bone-implant interface.

Immediate loading in the fully edentulous maxilla without bone grafting: the V-II-V technique

AIM

The aim of this prospective study was to evaluate a new surgical approach for the immediate rehabilitation of fully edentulous maxilla without any type of bone grafting.

METHODS

The technique named ''V-II-V'' consists of an immediately loaded full-arch bridge supported by six implants. Two distal implants engage the posterior wall of the maxillary sinus, being tilted 30-45 degrees relative to the occlusal plane. Two other tilted implants engage the anterior wall of the sinus, and finally two axial implants are inserted in the anterior maxilla. An acrylic provisional restoration is delivered within 4 hours of implant placement. At each follow-up, plaque and bleeding indexes were scored, marginal bone level change around tilted and axial implants were evaluated, and a questionnaire was compiled to assess patient's satisfaction for function and aesthetics.

RESULTS

Twenty-one patients were rehabilitated. A total of 126 implants were inserted. Nineteen prostheses were in function for more than 12 months. The average follow-up was 20 months (range 4-35 months). No implant failure occurred to date, leading to 100% survival rate and 100% prosthesis success. No complication was recorded. Peri-implant bone loss at axial and tilted fixtures was similar at one year, being 0.8 mm (SD 0.4, N.=28) and.0.9 mm (SD 0.5 mm, N.=56) respectively (P>0.05).

RESULTS

The ''V-II-V'' technique is a viable treatment modality for the immediate rehabilitation of the edentulous maxilla, avoiding bone grafting or sinus augmentation. Long-term evaluation is needed to confirm these encouraging preliminary

Immediate rehabilitation of the mandible with fixed full prosthesis supported by axial and tilted implants: interim results of a single cohort prospective study

PURPOSE

The aims of this prospective study were to assess the treatment outcome of immediately loaded full-arch fixed bridges anchored to both tilted and axially placed implants for the rehabilitation of the mandible and to compare the outcome of axial versus tilted implants.

MATERIALS AND METHODS

Sixty-two patients (34 women and 28 men) were included in the study. Each patient received a full-arch fixed bridge supported by two axial implants and two distal tilted implants (All-on-Four, Nobel Biocare AB, Göteborg, Sweden). Loading was applied within 48 hours of surgery. Patients were scheduled for follow-up at 6, 12, 18, and 24 months, and annually up to 5 years. At each follow-up, plaque level and bleeding scores were assessed; moreover, patient's satisfaction for aesthetics and function was evaluated by a questionnaire. Radiographic evaluation of marginal bone level change was performed at 1 year.

RESULTS

The overall follow-up range was 6 to 43 months (mean 22.4 months). Forty-four patients were followed for a minimum of 1 year. No implant failures were recorded to date, leading to a cumulative implant survival and prosthesis success rate of 100%. Plaque level and bleeding scores showed progressive decrease over time, parallel to increase of satisfaction for both aesthetics and function. No significant difference in marginal bone loss was found between tilted and axial implants at 1-year evaluation.

CONCLUSION

The present preliminary data suggest that immediate loading associated with tilted implants could be considered a viable treatment modality for the mandible.

Sequential tamoxifen and aminoglutethimide versus tamoxifen alone in the adjuvant treatment of postmenopausal breast cancer patients: results of an Italian cooperative study

PURPOSE

To determine whether switching patients from tamoxifen to antiaromatase treatment would prevent some of the relapses or deaths that we assume would occur if tamoxifen were continued.

PATIENTS AND METHODS

Three hundred eighty postmenopausal breast cancer patients receiving adjuvant tamoxifen treatment for 3 years were randomized to either continue tamoxifen for 2 more years or to switch to low-dose aminoglutethimide (250 mg daily) for 2 years.

RESULTS

At a median follow-up of 61 months (range, 5 to 94 months), 59 events occurred in the tamoxifen group, and 55 occurred in the aminoglutethimide group. More treatment failures at distant sites, such as viscera (P =.02), were observed in the tamoxifen group. Although no differences in disease-free survival between the two groups have emerged so far, a significant trend favors aminoglutethimide in overall survival (P =.005) and breast cancer-specific survival (P =.06). Even if more patients in the antiaromatase group complained of drug-related side effects and more of them discontinued treatment (P =.0001), the number of cardiovascular events and, in general, of life-threatening adverse events was higher in the tamoxifen arm.

CONCLUSION

Switching patients from tamoxifen to aminoglutethimide treatment resulted in comparable event-free survival, but longer overall survival was achieved in patients who were switched to aminoglutethimide as compared with those who continued to receive tamoxifen. Should these preliminary results be confirmed by larger studies with a similar design, which are now testing the effectiveness of the new, more active, and tolerable aromatase inhibitors, sequencing tamoxifen with an aromatase inhibitor could become a preferable alternative to tamoxifen alone in early breast cancer patients.

Serial color-word test predicts outcome of pharmacological treatment for panic disorder

A group of 50 outpatients with Panic Disorder were given the Serial Color-Word Test at the beginning of a standard pharmacological treatment (selective serotonin reuptake inhibitors and benzodiazepines). A single treating psychiatrist, blind to test results, judged therapy outcome at a 5-mo. follow-up. Among the main types of adaptation to conflict assessed by the test (Stabilized, Cumulative, Dissociative, and Cumulative-Dissociative), the Stabilized pattern predicted a good therapy outcome. Response to therapy among the patients with a Stabilized pattern was judged as more often good and less often moderate or poor, compared with the members of the other three adaptation classes (p=.004), and specifically with the patients resorting to a Cumulative strategy (p=.005).

[The capacity of the rest-dobutamine gated SPECT protocol to predict contractile recovery after revascularization of myocardial dysinergic areas]

INTRODUCTION AND AIM

Gated-SPECT is a promising method to analyze myocardial viability. We have assessed the accuracy of a new protocol of rest/Dobutamine gated-SPECT, based on the evaluation of contractile reserve induced by 10 microg/kg/min of Dobutamine, to predict contractile recovery after revascularization of dysinergic myocardial territories.

PATIENTS AND METHODS

In a group of 36 patients submitted to percutaneous revascularization, we selected 40 vascular territories (21 left descending artery, 19 right coronary-circumflex) with severely depressed contractility (contrast ventriculography, center line method). Follow up evaluation at 6 months showed the absence of angiographic restenosis and control contrast ventriculography assessed the contractile changes of the selected territories, considering those with contractile restoration as viable. Before revascularization, rest/Dobutamine gated-SPECT study was applied and viability was defined as the presence of contractile reserve (positive or improvement [n = 21] and negative or impairment [n = 7]) with non viability being the absence of contractile reserve (n = 12). We analyzed the evolution of the ejection fraction in a group of 27 patients with impaired ventricular function and complete revascularization.

RESULTS

Gated-SPECT showed a sensitivity of 0.96 (95% CI 0.78-0.99) and a specificity of 0.78 (95% CI 0.48-0.94) in the diagnosis of viability. The ejection fraction (median [interquartile range]) increased after revascularization: 0.42 (0.15) vs 0.55 (0.22), Z = -3.9; p < 0. 001. The diagnosis of viability by gated-SPECT (p < 0.001) and the extent of severely depressed myocardium (p = 0.04) independently predicted the increase of the ejection fraction after revascularization.

CONCLUSIONS

The analysis of contractile reserve by rest/Dobutamine gated-SPECT is adequate to diagnose viability in territories with severely depressed contractility and independently predicts the increase of ejection fraction after revascularization.

Cyclophosphamide, methotrexate, and fluorouracil versus tamoxifen plus ovarian suppression as adjuvant treatment of estrogen receptor-positive pre-/perimenopausal breast cancer patients: results of the Italian Breast Cancer Adjuvant Study Group 02 randomized trial. boccardo@hp380.ist.unige.it

PURPOSE

To compare the efficacy of chemotherapy versus that of tamoxifen plus ovarian suppression in pre-/perimenopausal estrogen receptor-positive patients with early breast cancer.

PATIENTS AND METHODS

Patients were randomly assigned to receive either six cycles of a standard regimen of cyclophosphamide 100 mg/m(2) orally days 1 to 14, methotrexate 40 mg/m(2) intravenously (IV) days 1 and 8, and fluorouracil 600 mg/m(2) IV days 1 and 8 (CMF), with all drugs restarted on day 29, or 5 years of tamoxifen, 30 mg/d, plus ovarian suppression with surgical oophorectomy, ovarian irradiation, or monthly goserelin 3.6-mg injections. Disease-free survival was the main study end point. Overall survival and toxicity were additional end points.

RESULTS

Between 1989 and 1997, 120 patients were assigned to CMF and 124 to tamoxifen and ovarian suppression (oophorectomy, n = 6; ovarian irradiation, n = 31; and goserelin injections, n = 87). At the time of analysis (median follow-up time, 76 months; range, 9 to 121 months), 82 patients had relapsed and 39 had died. No difference between groups had emerged with respect to either disease-free or overall survival. Treatments were comparable even in respect to age, tumor size, and nodal status, although a nonsignificant trend favored patients with poorly differentiated tumors treated with CMF. Leukopenia, nausea, vomiting, stomatitis, and alopecia were significantly more common in patients treated with CMF. There were few patients who developed benign gynecologic changes in either group, and numbers were comparable.

CONCLUSION

The combination of tamoxifen with ovarian suppression seems to be safe and to yield comparable results relative to standard CMF.

Aspartic protease inhibitors. An integrated approach for the design andsynthesis of diaminodiol-based peptidomimetics

Aspartic proteases play key roles in a variety of pathologies, including acquired immunodeficiency syndrome. Peptidomimetic inhibitors can act as drugs to combat these pathologies. We have developed an integrated methodology for preparing human immunodeficiency virus (HIV)-1 aspartic protease diaminodiol inhibitors, based on a computational method that predicts the potential inhibitory activity of the designed structures in terms of calculated enzyme-inhibitor complexation energies. This is combined with a versatile synthetic strategy that couples a high degree of stereochemical control in the central diaminodiol module with complete flexibility in the choice of side chains in the core and in flanking residues. A series of 23 tetrameric, pentameric and hexameric inhibitors, with a wide range of calculated relative complexation energies (-47.2 to +117 kJ.mol-1) and predicted hydrophobicities (logPo/w = 1.8-8.4) was thus assembled from readily available amino acids and carboxylic acids. The IC50 values for these compounds ranged from 3.2 nM to 90 microM, allowing study of correlations between structure and activity, and individuation of factors other than calculated complexation energies that determine the inhibition potency. Multivariable regression analysis revealed the importance of side-chain bulkiness and rigidity at the P2, P2' positions, suggesting possible improvements for the prediction process used to select candidate structures.

[Lymphedema of the upper extremity in patients operated for carcinoma of the breast: clinical experience with coumarinic extract from Melilotus officinalis]

OBJECTIVES

The aim of this clinical study was to verify the therapeutic activity of cumarinic extract of Melilotus officinalis (CEMO) in patients with chronic lymphedema of the upper arm caused by lymphadenectomy for breast cancer. Cumarine, in fact, has antiedemic properties due to macrophagic action that stimulates proteolysis in the tissues affected by chronic lymphedema.

PATIENTS AND METHODS

In an open clinical study we enrolled 24 patients with chronic upper arm lymphedema due to post-lymphadenectomy of the axilla for breast cancer. 21 patients were eligible to receive 400 mg of CEMO containing 8 mg of cumarine in a sole daily administration for 6 months. We measure the circumference of the upper arm at 3 and 6 months from treatment. We evaluated the symptoms and tolerability through a questionnaire given to the patients at every clinical control.

RESULTS

Of the 21 (87.5%) patients eligible, only 14 (66.6%) were treated with CEMO according to protocol. Of these 11 patients (52.3%) had a reduction of the circumference of the affected arm of 5% with respect to base values. Three patients (14.2%) had no change. In 12 patients (57.1%) symptoms improved. As for tolerability: 3 patients (14.2%) had transitory gastrointestinal side-effects. There was worsening of lymphedema and symptoms in 4 patients (19%) that did not receive CEMO and were followed as controls. Three patients (14.2%) were not evaluable because they were lost to follow-up.

CONCLUSIONS

Cumarinic extract of Melilotus officinalis (CEMO) was effective in reducing lymphedema in 79% of the pts treated for a period of six months. The median reduction of the upper arm circumference was modest (5% with respect to initial values) but statistically significant (p = 0.048). Treatment with CEMO for lymphedema could be associated to the physiotherapy given to these patients such as manual lymph drainage (MLD).

[Validation of the three-dimensional method of sestamibi gated-SPECT in the calculation of the left ventricular ejection fraction in patients with ischemic heart disease. Comparison with contrast ventriculography]

INTRODUCTION AND OBJECTIVE

Tomography with acquisition synchronized with electrocardiography, gated-tomography, allows the assessment of left ventricular contractile function. The accuracy of a new method of gated-tomography, based on the three dimensional representation of the left ventricle to calculate the ejection fraction was validated by means of comparison with contrast ventriculography.

METHODS

We studied 85 patients with ischemic cardiopathy, and ejection fraction was calculated by contrast ventriculography and sestamibi-gated-tomography, at rest and throughout 10 micrograms/kg/min of dobutamine. Furthermore, we assessed the extent of perfusion defect, as well as the number of segments with activity below 50% of the total 13 segments in which the tomographic slices were divided.

RESULTS

Gated-tomography was significantly correlated to contrast ventriculography in the calculation of ejection fraction, both with acquisition at rest (r = 0.80) and throughout Dobutamine (r = 0.82). The average underestimation of gated-tomography calculation of ejection fraction was significantly greater for the rest study (-0.12 [IC 95% 0.04, -0.30]) than the dobutamine study (-0.07 [IC 95% 0.09, -0.24]). Patients with greater perfusion defects (4 o more segments) had no differences in underestimation of ejection fraction (-0.13 [IC 95% 0.03, -0.30] versus -0.11 [IC 95% 0.07, -0.29]).

CONCLUSIONS

The three-dimensional method of gated-tomography accurately assesses the ejection fraction. The underestimation determined by this method was lower in the study done with viable doses of dobutamine. The extent of perfusion defect had no deleterious effect on gated-tomography in the calculation of ejection fraction.

Rational design of inhibitors for drug-resistant HIV-1 aspartic protease mutants

This report describes a method for the assessment of inhibitor binding affinities to wild type HIV-1 aspartic protease and to its drug-resistant mutant forms. We have elaborated a refined method for molecular modeling of the 3D structures of mutant enzymes and enzyme-inhibitor complexes based on the crystal structure of the wild type form, which employs a full thermodynamic cycle. Model complexes of four HIV-1 aspartic protease mutants with ten analogs of the A77003 inhibitor were considered. Predictions of inhibition efficiency, resistance potential, and hydrophilicity of the redesigned A77003 analogs were obtained by employing molecular mechanics for the evaluation of enzyme-inhibitor complexation energy and the polarizable continuum model for the estimation of solvent effects. Simple qualitative indicators for structural modifications aimed at overcoming the emergence of HIV resistance to protease inhibitors and at increasing the bioavailability of pseudopeptide inhibitors are examined. A semi-quantitative method for the description of enzyme-ligand binding and its implications for the rational design of inhibitors with higher binding affinity towards emerging HIV PR mutants is presented.

Identification of the start sites for the 1.9- and 1.4-kb rat transforming growth factor-beta1 transcripts and their effect on translational efficiency

Three distinct transforming growth factor-beta1 (TGF-beta1) transcripts of 2.5, 1.9 and 1.4kb have been described, but the start sites and functional significance of the shorter transcripts are unknown. Here, we have cloned and sequenced a rat genomic fragment encoding approximately 1250 bases upstream of the start of the TGF-beta1 open reading frame. Using a combination of ribonuclease protection and 5' RACE-PCR analysis, we have mapped the start sites for the two shorter TGF-beta1 transcripts in NRP152 cells, a rat prostatic epithelial cell line that expresses all three transcripts at high levels. The 1.4-kb mRNA starts 25 bases upstream of the initiator AUG, whereas the 1.9-kb mRNA has two start sites 366 and 401 bases upstream of the AUG. Polysome analysis of the NRP152 cells indicates that the 1.9-kb transcript is very efficiently translated, whereas the 2.5- and 1.4-kb transcripts appear to be poorly translated. Differential regulation of TGF-beta1 transcript size may therefore represent an important mechanism for regulating TGF-beta1 protein levels.

Wide-spectrum antibiotic activity of synthetic, amphipathic peptides

PGYa and PGAa are synthetic, amphipathic, alpha-helical peptides that were designed using a novel "sequence template" approach. Their antimicrobial activity was tested against several pathogenic clinical isolates, most of which were multiply resistant to conventional antibiotics. PGYa appeared to be more active towards Gram-positive species (MIC = 0.5-4 microM), towards such Gram negative species as P. aeruginosa, X. maltophilia, E. coli, K. pneumoniae and S. enteritidis (MIC = 1.4 microM), and towards the filamentous fungus A. niger (MIC = 8 microM). Conversely, PGAa showed the greater activity towards three Candida species (MIC = 2.16 microM). The peptides were shown to have a bactericidal activity, resulting in a decrease of viability for both Gram-positive and -negative bacteria of 3-6 logs within 60 min. Scanning electron microscopy of S. aureus and E. coli treated with PGYa shows considerable roughening and blebbing of the bacterial surfaces providing conclusive evidence that the peptide is membrane active.

A computational study of the resistance of HIV-1 aspartic protease to the inhibitors ABT-538 and VX-478 and design of new analogues

Recent experimental findings with HIV-1 protease (HIV-1 PR) mutants containing variations at four residues, M46I, L63P, V82T and I84V, have shown that only mutants containing the latter two exhibit cross resistance to the inhibitors ABT-538 and VX-478. The V82T and I84V modifications in fact concern residues in the active site while the other two are in the flap (M46I) and hinge (L63P) domains of the enzyme. We have modelled the M46I/L63P, V82T/I84V and M46I/L63P/ V82T/I84V (4X) mutants of HIV-PR and computed their complexation energies with these two inhibitors. A good correlation was found between these complexation energies and the trend in published inhibition constants for these inhibitors. Reasons for the decrease in binding affinities with the two critical mutants (V82T/I84V and 4X) have also been elucidated in detail. Based on these findings, we have designed several analogues of ABT-538 and VX-478, some of which show a better calculated binding affinity towards both mutant and wild type PR.

Design of synthetic antimicrobial peptides based on sequence analogy and amphipathicity

Novel alpha-helical antimicrobial peptides have been devised by comparing the N-terminal sequences of many of these peptides from insect, frog and mammalian families, extracting common features, and creating sequence templates with which to design active peptides. Determination of the most frequent amino acids in the first 20 positions for over 80 different natural sequences allowed the design of one peptide, while a further three were based on the comparison of the sequences of alpha-helical antimicrobial peptides derived from the mammalian cathelicidin family of precursors. These peptides were predicted to assume a highly amphipathic alpha-helical conformation, as indicated by high mean hydrophobic moments. In fact, circular dichroism experiments showed clear transitions from random coil in aqueous solution to an alpha-helical conformation on addition of trifluoroethanol. All four peptides displayed a potent antibacterial activity against selected gram-positive and gram-negative bacteria (minimum inhibitory concentrations in the range 1-8 microM), including some antibiotic resistant strains. Permeabilization of both the outer and cytoplasmic membranes of the gram-negative bacterium, Escherichia coli, by selected peptides was quite rapid and a dramatic drop in colony forming units was observed within 5 min in time-killing experiments. Permeabilization of the cytoplasmic membrane of the gram-positive bacterium, Staphylococcus aureus, was instead initially quite slow, gathering speed after 45 min, which corresponds to the time required for significant inactivation in time-killing studies. The cytotoxic activity of the peptides, determined on several normal and transformed cell lines, was generally low at values within the minimum inhibitory concentration range.

Recharacterization of the start sites for the major human transforming growth factor-beta 1 mRNA

The start sites for the major human TGF-beta 1 transcripts have been reexamined. A comparison of ribonuclease and S1 nuclease protection analyses on native TGF-beta 1 mRNA and in vitro transcribed human TGF-beta 1 transcripts of defined sizes places the most 5' start site for the native TGF-beta 1 message approx. 50 nucleotides upstream from the previously published start site at base +1. Furthermore, the same techniques indicate that the apparent downstream start site at base +271 is an artefact due to the presence of an A + T-rich island in the middle of an otherwise highly G + C-rich sequence. This is not apparent if S1 nuclease protection is used alone, which emphasizes the importance of using the two techniques in combination for this type of analysis. Thus the major 2.5 kb TGF-beta 1 band seen on Northern blots comprises only mRNA transcribed from the more upstream of the two previously characterized promoters. This has important implications both for the transcriptional and translational regulation of this growth factor.

Healthcare decisions and product labeling: results of a consumer comprehension study of prototype labeling for proposed over-the-counter cholestyramine

This study was designed to determine whether randomly selected subjects could comprehend prototype consumer-oriented package labeling and inserts for over-the-counter cholestyramine, a nonsystemic lipid-lowering agent. The primary messages communicated in the label were that consumers should see their doctor before taking cholestyramine and should read the full package insert. In addition, the label communicated indication, dosage, and preparation, as well as key warnings about use with other medications. The insert reinforced the message about seeing the doctor before taking cholestyramine and before taking concurrent medications, further explained the purpose of the drug and its correct use, and provided information about the two types of cholesterol, risk factors for heart disease, and the importance of diet and exercise. A total of 1,806 randomly selected subjects were interviewed in their homes in 40 geographic regions. After examining the product container with one of the three labels being tested, they were given a questionnaire to test their understanding of the label communication points. They were then asked to read the package insert and tested on their understanding of the messages it communicated. Responses were analyzed by gender, age, and education level, as well as by label format. For the education-level subgroup analysis, the high-school-nongraduate group was supplemented by 419 subjects, for a total of 2,225 subjects. Statistical analyses were performed on completed questionnaires by an independent data analysis company. The net correct response to the two primary communication objectives was 99% among the total population. Responses to questions addressing the use of concurrent medications; types of cholesterol; purpose, dosage, and preparation of the medication; and diet and exercise were also clearly understood. This study showed a high level of comprehension of the purpose and correct use of cholestyramine among both high-school graduates and nongraduates.

Purification and structural characterization of bovine cathelicidins, precursors of antimicrobial peptides

Cathelicidins are a novel family of antimicrobial peptide precursors from mammalian myeloid cells. They are characterized by a conserved N-terminal region while the C-terminal antimicrobial domain can vary considerably in both primary sequence and length. Four cathelicidins, proBac5, proBac7, prododecapeptide and proBMAP-28, have been concurrently purified from bovine neutrophils, using simple and rapid methodologies. The correlation of ES-MS data from the purified proteins with their cDNA-deduced sequences has revealed several common features of their primary sequence, such as the presence of N-terminal 5-oxoproline (pyroglutamate) residues and two disulfide bridges in a 1-2, 3-4 arrangement. The N-terminal domains of the cathelicidins present one or two Asp-Pro bonds, which are particularly acid-labile in proBac5 and proBac7, but stable in prododecapeptide. This suggests that the spatial organization around these bonds may vary in different cathelicidins, and favour hydrolysis in some cases. An unexpected feature of the prododecapeptide is that it exists as dimers formed by three possible combinations of its two isoforms. The isolation of a truncated, monomeric form of this protein, lacking the cysteine-containing antimicrobial dodecapeptide, indicates that dimerization occurs via disulfide bridge formation at the level of the C-terminal domain and that the dodecapeptide is likely released as a dimer from its precursor. Sequence-based secondary structure predictions and CD results indicate for cathelicidins a 30-50% content of extended conformation and <20% content of alpha-helical conformation, with the alpha-helical segment placed near the N-terminus. Finally, similarity searching and topology-based structure prediction underline a significant sequential and structural similarity between the conserved N-terminal domain of cathelicidins and cystatin-like domains, placing this family within the cystatin superfamily. When assayed against cathepsin L, unlike the potent cystatin inhibitors, three of the four cathelicidins show only a poor inhibitory activity (Ki = 0.6-3 microM).

Development of pseudopeptide inhibitors of HIV-1 aspartic protease: analysis and tuning of the subsite specificity

HIV-1 aspartic protease (PR) is a promising target for acquired immunodeficiency syndrome (AIDS) therapy, and the development of PR inhibitors can be accelerated by computer-aided design methods. We describe an approach for the design of new inhibitors, based on the modification of a known reference inhibitor, and the calculation of relative binding energies, taking into account contributions from all species in the binding equilibrium (inhibitor, PR and inhibitor/PR complex), as well as their solvation. This allows for a rational selection of new structures that are likely to have increased inhibition potency. We have analyzed reduced amide bond hexapeptides (Ac-P3-P2-P1-phi[CH2-NH]-P1'-P2-P3'-NH2), based on the structure of the known inhibitor MVT-101. A maximum gain in binding energy (approximately -55 kcal/mol) is observed when Phe or Tyr are present in positions P1 and P1', Glu in position P2' and aromatic residues (Phe, Trp or Tyr) in positions P3 and P3', while, in general, the presence of positively charged residues is destabilizing. This specificity is explained in terms of the interaction of individual inhibitor residues with proximal and distal PR residues. The validity of this computational approach has been confirmed by solid-phase synthesis of several of the designed pseudopeptides, followed by in vitro enzyme inhibition assaying. The best candidate structures show IC50 values in the low nanomolar range.

Cathelicidins: a novel protein family with a common proregion and a variable C-terminal antimicrobial domain

A novel protein family, showing a conserved proregion and a variable C-terminal antimicrobial domain, and named cathelicidin, has been identified in mammalian myeloid cells. The conserved proregion shows sequence similarity to members of the cystatin superfamily of cysteine proteinase inhibitors. Cathelicidins are stored in the cytoplasmic granules of neutrophil leukocytes and release the antimicrobial peptides upon leukocyte activation. Some of these peptides can assume an alpha-helical conformation, others contain one or two disulfide bonds, still others are Pro- and Arg-rich, or Trp-rich. In addition to bacterial killing, some of these peptides exert additional functions related to host defense such as LPS-neutralization and promotion of wound healing.

Molecular cloning of Bac7, a proline- and arginine-rich antimicrobial peptide from bovine neutrophils

Bac7 is a 7 kDa proline- and arginine-rich antimicrobial peptide which was purified from bovine neutrophils. We have used PCR to clone the cDNA of Bac7 precursor, a polypeptide of 21,569 Da. This cDNA is highly conserved in the 5' region, with respect to the corresponding region in the precursors of several other structurally unrelated myeloid antimicrobial peptides. Furthermore, a 148 nt non-coding region at the 3' end is 75% homologous to a corresponding region of the cDNA of the precursor of PR-39, a porcine antibacterial peptide which is also proline- and arginine-rich.

Transforming growth factor-beta: expression in normal and pathological conditions

Expression of the various isoforms of transforming growth factor-beta (TGF-beta) is differentially controlled both in vivo and in vitro. Characterization of the molecular mechanisms governing expression of TGF-beta isoforms now provides a basis for understanding the selective regulation of expression of the TGF-beta s by a variety of factors including oncogenes and tumor suppressor genes. In addition to transcriptional control, data suggest that expression of TGF-beta s is also regulated posttranscriptionally. Regulation of TGF-beta s by steroids and retinoids appears to involve predominantly posttranscriptional mechanisms. Identification of these mechanisms may contribute to the understanding of the regulatory events controlling cellular proliferation and differentiation by TGF-beta s and steroids/retinoids.

Antimicrobial activity of two bactenecins against spirochetes

Bac5 and Bac7 are antimicrobial peptides of bovine neutrophils that act on enteric gram-negative bacteria. We report here that these two peptides immobilize and kill Leptospira interrogans and Leptospira biflexa with MBCs of 6 to 25 micrograms/ml. Conversely, although both peptides bind to Borrelia burgdorferi, the organism is resistant to their action.

Characterization of bovine neutrophil antibacterial polypeptides which bind to Escherichia coli

Bovine neutrophils contain several cationic polypeptides which exert potent microbicidal effects in vitro. To better characterize the repertoire of these polypeptides, we have incubated extracts of bovine neutrophils or neutrophil granules at pH 4 or 7 with either a smooth strain of Escherichia coli or a rough one. Only a few polypeptides interacted with the bacterial surface and were subsequently desorbed with 200 mM MgCl2, as revealed by gel electrophoresis and analysis of Western blots (immunoblots) with appropriate antibodies. Two of the main proteins appearing in Coomassie blue-stained gels have molecular masses of 53 and 15 kDa and correspond to the heavy and light chains of myeloperoxidase. Another prevailing protein band with a molecular mass of 31 kDa was purified and shown to be 87% identical to human azurocidin/CAP37 in its 22-amino-acid N-terminal sequence. Proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and blotted to nitrocellulose did not react with an antiserum to human bactericidal/permeability-increasing protein. Conversely, immunoglobulin G against Bac7 or Bac5, two members of the antimicrobial proline- and arginine-rich polypeptide family, recognized in Western blots both the inactive precursor molecules, proBac7 and proBac5, and the mature polypeptides.

Chemotactic and protease-inhibiting activities of antibiotic peptide precursors

We have recently shown that two antimicrobial peptides (Bac5 and Bac7) and/or their immature forms (proBac5 and proBac7) can be released extracellularly from activated neutrophils. In the present study we have investigated the biological activities of the immature forms, which do not exhibit antimicrobial effects. We show that proBac7 is a monocyte-selective chemoattractant, potentially contributing to the recruitment of these cells to infection sites, whereas proBac5 efficiently inhibits the in vitro activity of cathepsin L, a cysteine proteinase thought to contribute to tissue injury in inflammation.

The cDNA of the neutrophil antibiotic Bac5 predicts a pro-sequence homologous to a cysteine proteinase inhibitor that is common to other neutrophil antibiotics

Bac5 is a 5-kDa proline- and arginine-rich antibiotic, stored as inactive precursor (proBac5) in the large granules of bovine neutrophils. A full-length cDNA encoding the precursor form of Bac5 has been cloned. The encoded protein (pre-proBac5) has a calculated mass of 20,031 Da and a pI of 9.21. This comprises a putative signal peptide of 29 amino acid residues and a 101-residue pro-sequence that precede the mature antibiotic. The pro-sequence is acidic and may neutralize the highly cationic Bac5, thus accounting for the inactivation of the antibiotic activity observed in in vitro experiments. The structure of mature Bac5 agrees closely with the amino acid sequence previously determined, with an additional tripeptide tail predicting carboxyl-terminal amidation. A valyl residue is deduced at the cleavage site for the proteolytic maturation of proBac5, consistent with a previous observation showing elastase as the enzyme involved in this processing step. The region upstream of Bac5 reveals high identity to corresponding regions of two neutrophil antimicrobial polypeptides, CAP18 from rabbit and bovine indolicidin. The COOH-terminal sequences of these antibiotics are completely unrelated. The proregion also exhibits remarkable similarity to pig cathelin, an inhibitor of cathepsin L, indicating a common evolutionary origin.