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Objectives: Can a synthetic bone substitute be used to repair the alveolar cleft to bypass donor site morbidity as well as to shorten the operating time? In earlier experimental studies, micro-structured beta-tricalcium phosphate (β-TCP) provided similar bone healing when compared with grafting with iliac crest bone. This justifies the clinical evaluation of this bone substitute in the human alveolar cleft situation., Design: Prospective clinical study., Setting: University clinic., Participants: Seven patients, all with unilateral alveolar cleft, were randomly included for alveolar cleft repair with β-TCP in 2010 and 2011., Main Outcome Measures: In all patients, the alveolar cleft was repaired by micro-structured β-TCP grafting. Our assessments were distilled from cone beam computed tomography scans taken preoperatively, 1 week postoperatively, and 6 months postoperatively. A volumetric outcome could be realized., Results: Six months after the operative grafting of micro-structured β-TCP into the alveolar cleft, the bone volume thus acquired was satisfactory. We found an average bone volume percentage of 73% ± 6% compared with the original cleft volume., Conclusions: Previous experimental and clinical studies and the initial findings of this pilot study now elucidate a path toward the clinical use of micro-structured β-TCP bone substitute for repair of the alveolar cleft.

Background: Permanent coronary artery damage is a hazardous complication of epicardial radiofrequency ablation. Irreversible electroporation (IRE) is a promising nonthermal ablation modality able to create deep myocardial lesions. We investigated the effects of epicardial IRE on luminal coronary artery diameter and lesion depth., Methods and Results: In 5 pigs (60-75 kg), the pericardium was exposed using surgical subxiphoidal epicardial access. A custom deflectable octopolar 12-mm circular catheter with 2-mm ring electrodes was introduced in the pericardium via a steerable sheath. After coronary angiography (CAG), the proximal, mid, and distal left anterior descending, and circumflex coronary arteries were targeted with a single, cathodal 200 J application. CAG was repeated after IRE and after 3 months follow-up. Using quantitative CAG, the minimal luminal diameter at the lesion site was compared with the average of the diameters just proximal and distal to that lesion. Intimal hyperplasia and lesion size were measured histologically. CAG directly postablation demonstrated short-lasting luminal narrowing with normalization in the targeted area, suggestive of coronary spasm. After 3 months, all CAGs were identical to preablation CAGs: mean reference luminal diameter was 2.2±0.3 mm, mean luminal diameter at the lesion site was 2.1±0.3 mm (P=0.35). Average intimal hyperplasia in all arteries was 2±4%. Median lesion depth was 6.4±2.6 mm., Conclusions: Luminal coronary artery diameter remained unaffected 3 months after epicardial IRE, purposely targeting the coronary arteries. IRE can create deep lesions and is a safe modality for catheter ablation on or near coronary arteries., (© 2014 American Heart Association, Inc.)

Background: Irreversible electroporation is a promising nonthermal ablation modality able to create deep myocardial lesions. We investigated lesion size after epicardial electroporation catheter ablation with various energy levels after subxiphoid pericardial puncture., Methods and Results: In six 6-month-old pigs (60-75 kg), a custom deflectable octopolar 12-mm circular catheter with 2-mm ring electrodes was introduced via a deflectable sheath after pericardial access by subxiphoid puncture. Nonarcing, nonbarotraumatic, cathodal 50, 100, and 200 J electroporation applications were delivered randomly on the basal, mid and lateral left ventricle. After 3-month survival, myocardial lesion size and degree of intimal hyperplasia of the coronary arteries were analyzed histologically. Five animals survived the follow-up without complications and 1 animal died of shock after the subxiphoid puncture. At autopsy, whitish circular scars with indentation of the epicardium could be identified. Average lesion depths of the 50-, 100-, and 200-J lesions were 5.0±2.1, 7.0±2.0, and 11.9±1.5 mm, respectively. Average lesion widths of the 50-, 100-, and 200-J lesions were 16.6±1.1, 16.2±4.3, and 19.8±1.8 mm, respectively. In the 100- and 200-J cross sections, transmural left ventricular lesions and significant tissue shrinkage were observed. No intimal hyperplasia of the coronary arteries was observed., Conclusions: Epicardial electroporation ablation after subxiphoid pericardial puncture can create deep, wide, and transmural ventricular myocardial lesions. There is a significant relationship between the amounts of electroporation energy delivered epicardially and lesion size in the absence of major adverse events., (© 2014 American Heart Association, Inc.)

Background: Electroporation can be used as a nonthermal method to ablate myocardial tissue. However, like with all electrical ablation methods, determination of the energy supplied into the myocardium enhances the clinically required controllability over lesion creation., Objective: To investigate the relationship between the magnitude of epicardial electroporation ablation and the lesion size using an electrically isolating linear suction device., Methods: In 5 pigs (60-75 kg), the pericardium was opened after medial sternotomy. A custom linear suction device with a single 35 × 6-mm electrode inside a 42-mm-long and 7-mm-wide plastic suction cup was used for electroporation ablation. Single cathodal applications of 30, 100, or 300 J were delivered randomly at 3 different epicardial left ventricular sites. Coronary angiography was performed before ablation, immediately after ablation, and after 3 months survival. Lesion size was measured histologically after euthanization., Results: The mean depth of 30, 100, and 300 J lesions was 3.2 ± 0.7, 6.3 ± 1.8, and 8.0 ± 1.5 mm, respectively (P = .0003). The mean width of 30, 100, and 300 J lesions was 10.1 ± 0.8, 15.1 ± 1.5, and 17.1 ± 1.3 mm, respectively (P<.0001). Significant tissue shrinkage was observed at the higher energy levels. No luminal arterial narrowing was observed after 3 months: 2.3 ± 0.3 mm vs 2.3 ± 0.4 mm (P = .85)., Conclusion: The relationship between the amount of electroporation energy delivered through a linear suction device with a single linear electrode and the mean myocardial lesion size is significant in the absence of major adverse events or permanent damage to the coronary arteries., (Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study was to evaluate the use of synthetic bone graft material as a filling material at the mandibular symphysis donor site of autologous bone in children., Materials and Methods: A blinded patient group comprised 20 patients with unilateral (UCLP) or bilateral (BCLP) cleft of lip and palate, all with an indication for alveolar cleft repair. The study took the form of a prospective randomized clinical trial. We used lateral cephalograms for the measurement of the symphyseal donor area defect both peroperatively and at 12 months postoperatively. The data obtained were digitalized and the treatment outcome expressed in numbers. Comparisons with a previous study were made. Histology of biopsies and CT scans were used for visualising bone formation., Results: This study demonstrates that the micro-structured, resorbable calcium phosphate ceramic provides good regeneration properties for the repair of a critical size bony defect in children. One year postoperatively, the measurements taken from lateral cephalograms show that there is scarcely any visible residual defect. Histological investigations of the bone biopsies show solid, induced bone formation and almost complete resorption of the micro-structured calcium phosphate., Conclusions: The findings of this study (novel in children) indicate that micro-structured resorbable calcium phosphate is an excellent alternative to autologous bone. The digital findings showed a restored donor site defect significantly indicating the efficacy (i.e., osteoconductivity and resorbability) of this bone substitute. The biopsy histology demonstrated the overall presence of newly formed vital bone and the resorption of the bone substitute. Its use for grafting the alveolar cleft is currently researched and it may become the new standard., Clinical Relevance: As co-morbidity and prolonged operation time at the donor operation site are inherent to the alveolar cleft repair procedure, the use of the described bone substitute is winning progress., (Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

Myocardial fibrosis can lead to heart failure and act as a substrate for cardiac arrhythmias. In dilated cardiomyopathy diffuse interstitial reactive fibrosis can be observed, whereas arrhythmogenic cardiomyopathy is characterized by fibrofatty replacement in predominantly the right ventricle. The p.Arg14del mutation in the phospholamban (PLN) gene has been associated with dilated cardiomyopathy and recently also with arrhythmogenic cardiomyopathy. Aim of the present study is to determine the exact pattern of fibrosis and fatty replacement in PLN p.Arg14del mutation positive patients, with a novel method for high resolution systematic digital histological quantification of fibrosis and fatty tissue in cardiac tissue. Transversal mid-ventricular slices (n = 8) from whole hearts were collected from patients with the PLN p.Arg14del mutation (age 48±16 years; 4 (50%) male). An in-house developed open source MATLAB script was used for digital analysis of Masson's trichrome stained slides (http://sourceforge.net/projects/fibroquant/). Slides were divided into trabecular, inner and outer compact myocardium. Per region the percentage of connective tissue, cardiomyocytes and fatty tissue was quantified. In PLN p.Arg14del mutation associated cardiomyopathy, myocardial fibrosis is predominantly present in the left posterolateral wall and to a lesser extent in the right ventricular wall, whereas fatty changes are more pronounced in the right ventricular wall. No difference in distribution pattern of fibrosis and adipocytes was observed between patients with a clinical predominantly dilated and arrhythmogenic cardiomyopathy phenotype. In the future, this novel method for quantifying fibrosis and fatty tissue can be used to assess cardiac fibrosis and fatty tissue in animal models and a broad range of human cardiomyopathies.

A 90-year old woman attended a department of Oral and Maxillofacial Surgery with a tongue that had been painful for at least 3 months. Clinical examination revealed extensive bullous and ulcerative lesions located on the tongue, the oral vestibule and the buccal mucosa on both sides. A variety of diseases may be causative of ulcerative stomatitis: autoimmune diseases (like Pemphigus vulgaris, Erosive Lichen Planus, SLE or M. Crohn), or a viral, bacterial or mycotical infection, vitamin deficiency, a toxic reaction to medication or an immune deficiency. After an extensive, clinical examination, a definitive diagnosis still had not been achieved. The patient suffered from osteoporosis, for which she used alendronate (Fosamax). A study of the literature described a possible relationship between the occurrence of oral ulcers and the use of oral biphosphonates. Since a toxic reaction to alendronate was suspected, the use of Fosamax tablets was suspended. Three months later a complete recovery of the oral mucosa was observed.

The purpose of this study is to examine a cohort of patients with free-flap reconstruction prospectively and to identify the prognostic factors for postoperative medical and surgical complications. All 150 patients required a free-flap reconstruction after ablative surgery for a defect in the head and neck area. Medical complications and major surgical complications were correlated with patient factors. An ASA score of 3 and male gender were statistically significant prognostic factors for medical complications. The ASA scoring system is a slightly better prognostic factor for medical complications than Charlson comorbidity stage on forward logistic regression analysis. Female gender and an operation time exceeding 10h were statistically significant prognostic factors for major surgical complications.

A 58-year-old woman was referred by her dentist to a maxillofacial surgeon because of a rapidly increasing facial swelling. The swelling developed after sodium hypochlorite irrigation during the endodontic treatment of tooth 25. A mechanical heart valve, a heart rhythm disorder, and antithrombotic therapy were complicating medical conditions. Treatment consisted of 12 mg dexamethason administered once intravenously, augmentin administered thrice daily intravenously, and oral analgetics. Damage following sodium hypochlorite irrigation during endodontic treatment is a rare disorder which is associated with a severe reaction in the surrounding tissue. Damage can be permanent.

A 63-year-old man suffered from a cardiogenic shock. Upon echocardiography vegetations on the tricuspid valve were seen. As fever was absent, marantic endocarditis was diagnosed.

Oculodentodigital dysplasia (ODDD) is a rare, autosomal dominant pleiotropic disorder, caused by mutations in the Connexin 43 (Cx43 or GJA1) gene. Described here is the case of a 10-year-old girl with enamel hypoplasia, typical facies and mental delay, initially thought to be related to an unknown metabolic disorder. Careful clinical re-evaluation revealed a type of ODDD, characterised by the predominance of facial and ophthalmological involvement with mandibular retrognathism, and by the absence of cutaneous hand or foot syndactyly. A novel single-sequence variation (Nt460A>G) in exon 2, resulting in the substitution of alanine for threonine at amino acid 154, was found. These findings confirm once again the highly variable phenotypic expression caused by Cx43 mutations.

A 15-year-old autistic boy of subnormal intelligence appeared at the office of his dental practitioner complaining about pain in the third quadrant. Investigation revealed that the second molar could be intruded easily. No other irregularities, such as caries or periodontal disease were apparent. Due to the severe pain it was decided that the tooth should be extracted. Extraction of the tooth induced massive bleeding. Hemostasis was achieved by repositioning the molar in its alveolus, according to the principle of putting a cork in a bottle. Radiographic investigation showed the presence of an intraosseous arteriovenous malformation. These malformations are potentially life-threatening lesions. Treatment of choice is a combination of transarterial embolization and surgical removal of the malformation.

Extraoral implants are used with increasing frequency, in order to provide retention for facial prostheses. Facial prostheses can replace lost extraoral hard and soft tissues using acrylic or silicone materials. The surgeon, maxillofacial prosthodontist and dental technician are facing particular treatment considerations and practical problems. Some of these are demonstrated and discussed in this article by means of a case-report. A patient received an orbital prosthesis which obtains its retention from implants, placed in the lateral orbital rim.

A total of 22 NZW rabbits with VX2 squamous cell carcinomas transplanted into the auricles were intra-arterially (i.a.) embolized with radioactive or inactive holmium-labelled poly(L-lactic acid) (HoPLA) microspheres with a mean diameter of 38-80 microm. The effects on tumour growth, the efficiency of i.a. infusion, the efficacy of retention of microspheres in the primary tumour and the excretion of free holmium-166 were analyzed. Complete tumour remissions were obtained in 79% and 86% following embolization with radioactive and inactive microspheres, respectively. Over 95% of the microspheres were retained in the tumour and the leaching of holmium-166 in urine and faeces was less than 0.1% in 2 days. The injection efficiency was not optimal, as 40% of the microspheres were retained in the cannulation system. Arterio-arteriolar connections should be detected and closed prior to embolization to prevent stray emboli from entering the brain. It is concluded that 166HoPLA microspheres are promising candidates for further studies on radio-embolization of unresectable head-and-neck cancer.

Introduction: Intra-arterial embolization of unresectable malignant tumours with biodegradable microspheres is an effective way of selective anti-tumour therapy. Promising candidates are Dextran hydrogel (Dex) microspheres for chemo-embolization and Holmium-166 poly(L-lactic acid) (166HoPLA) microspheres for radio-embolization. This study was performed to investigate the distribution of intra-arterially injected microspheres both in vivo and histologically in order to establish an optimal size of particles for embolization of head and neck tumours., Material: Twenty rabbits with Vx2 auricular tumours were embolized via the caudal auricular artery with 4 different batches of microspheres: Radioactive (166)HoPLA microspheres sieved between 20 and 50 microm and Dextran hydrogel microspheres sieved between 20 and 100 microm (Dex20), 30 and 100 microm (Dex30) or 50 and 100 microm (Dex50). Dex20 and Dex50 microspheres were labelled with 99mTechnetium in six cases., Methods: The average particle size of the microspheres was determined. The proportion of microspheres entrapped in the tumour was measured with a gamma camera. The distribution of microspheres around the primary tumour and spill of particles over into lungs or other organs was analysed from histological sections., Results: The mean particle diameter varied from 19 to 66 microm: (166)HoPLA 19+/-11 microm, Dex20 40+/-19 microm, Dex30 50+/-19 microm, Dex50 66+/-21 microm. The 19 microm(166)HoPLA particles proved inadequate for embolization as 51% spilled over into the lungs, whereas over 95% of the 40-66 microm Dex microspheres were retained within the primary tumour area. Particle density in lung tissues proved significantly lower for the Dex50 group. Stray emboli to the brain occurred in two rabbits., Conclusion: The results of this investigation show that both Dextran hydrogel and holmium-166 poly(L-lactic acid) microspheres are potential candidates for embolization of head and neck cancer. In future studies, arterio-arteriolar anastomoses which might confound treatment should be identified and occluded. Particles with a number weighted mean diameter of at least 40 microm and a volume weighted mean size up to 70 microm should be used., (Copyright 2001 European Association for Cranio-Maxillofacial Surgery.)

Background: Head-and-neck cancer is associated with impaired cell-mediated immune reactivity. A rabbit model with VX2 Squamous Cell Carcinoma transplanted into both auricles was used to test the effects of a regimen for local Interleukin 2 (IL-2) therapy, optimal in murine tumour models., Materials and Methods: Peri-tumoural IL-2 treatment started when one of the tumours exceeded 2 cm2 and consisted of 100,000 or 300,000 Chiron Units IL-2 or only solvent during 5 consecutive days., Results: In 4 out of 12 (33%) rabbits the treated primary tumours regressed completely, simultaneously with the non-treated contra-lateral tumours. Also metastases in draining lymph nodes of both treated and untreated primary tumours regressed in three of these animals. Tumour cells injected in the cured animals were rejected. The histology of the regressing tumours in cured cases showed an active granulomatous reaction with a histiocytic response, splitting up of tumour islands, and fibrinoid obstruction of blood vessels., Conclusion: These findings showed local and systemic therapeutic effects of this local IL-2 regimen in a VX2 head-and-neck cancer model.

Introduction: This study investigates whether the VX2 carcinoma cell line, transplanted into the rabbit auricle, can be used as a head and neck cancer model. The biologic behaviour of this model is evaluated, comparing tumour transplantation with either tissue pieces or cell suspensions., Material: Thirty-six adult NZW rabbits received s.c. injections of VX2-suspensions (Group S) and 11 rabbits received solid VX2-pieces (Group P) into both auricles., Methods: In Group S, 16 rabbits were sacrificed at various days before (S1) and 15 after (S2) the 28th day following transplantation. In the other five rabbits transplantation failed. Animals from Group P were sacrificed every 2 weeks after the 28th day. At autopsy the size of the primary tumours and of lymph node, lung and other metastases were assessed. If transplantation failed, the maximal tumour size and the time at which regression took place were recorded. Exponential trend lines were used to create growth curves of metastases. Differences between groups were evaluated with the chi2 test, correlations between parameters with Kendall's tau., Results: The tumour take-rate in Groups S and P was 78% and 59% respectively. The maximal size and time at which regression occurred was significantly different, amounting to 83 +/- 7 mm2 at 10.4 +/- 1.6 days (Group S) and 243 +/- 30 mm2 at 20.9 +/- 2.0 days (Group P), respectively. Development of lymph node metastases was not different. In Groups P and S2, over 90% of the necks contained lymph node metastases. There was a higher incidence of lung metastases in Group S2 when compared to Group P (47% vs. 14%) but it was not statistically significant. A significant correlation (p<0.05) between weight loss and the size of lung metastases was found., Conclusion: Transplantation of the VX2-tumour with cell suspensions produces a useful head and neck cancer model for locoregional disease in which anti-tumour regimens against both the primary and lymph node metastases can be tested. Transplantation with tumour pieces is not advised as the take-rate is low and spontaneous remissions occur at a late stage.

This technical note aims to draw the surgeon's attention to the lingual artery in its course through Pirogoff's Triangle when looking for an appropriate recipient artery in the neck. Nowadays, free vascularised tissue transfer is used routinely in the reconstruction of defects in the maxillofacial area. Comfortable access to a healthy recipient artery is a major factor in ensuring a successful result. Traditionally, Pirogoff's Triangle is the ideal site to expose the lingual artery for ligation in case of severe haemorrhage of the tongue. This study shows that the lingual artery at this site is also well suited to perform a microvascular anastomosis, as the Triangle offers a convenient access, which is relatively horizontal and not hampered by the mandibular border. The artery is of good calibre and seems fairly resistant against arteriosclerosis.

Objective: To present a meta-analysis of current research on the prevalence, identification, and treatment of problem and compulsive gamblers., Quality of Evidence: Problem and compulsive gambling was not a socio-scientific concern until the last two decades. Hence research on this topic is limited. The summary and analysis for this paper relied on computer searches of journal and news abstracts in addition to direct contact with organizations addressing the identification and treatment of compulsive gamblers., Main Message: An estimated 5% of those who gamble run into problems. About 1% of those who gamble are predicted to experience serious problems. Successful treatment of problem and compulsive gambling continues to be a challenge. Although cognitive therapy has been the favoured approach, a combination of several therapeutic approaches is advocated., Conclusions: Problem and compulsive gambling can present a real health threat. As with other addictions, treatment strategies continue to be a baffling social problem. Aware and informed physicians can have a pivotal role in the difficult process of identifying, acknowledging, and remediating problem and compulsive gambling.

Two patients, a woman aged 21 and a man aged 29, with asymmetrical swellings of both mandibular angles and a painful, heavy sensation in the masticatory muscles (and in the woman also round the maxillary joint), were diagnosed as having hypertrophy of the masseter muscles. Both had the habit of jaw clenching and tooth grinding. Treatment consisted not of the traditional surgical debulking which also allows correction of overdeveloped osseous mandibular angles, but of injections with botulinum toxin type A. Injection of 40-60 IU (product: Botox) per muscle was followed by some atrophy; cosmetically satisfactory results were achieved after repetition of the treatment a few months later. Reduction of muscle volume was confirmed by a quantitative volumetric assessment of MRI scans. In the female patient, the pain also abated.

In order to compare the efficacy and safety of three regimens of long-term antithrombotic treatment in patients with acute ischaemic syndromes, a prospective, randomized, open-label, multicentre study is being conducted in which 60-70 Dutch hospitals will participate. Eligible patients discharged following hospitalization for acute myocardial infarction or unstable angina pectoris are randomly assigned to receive either (a) adjusted full intensity oral anticoagulation (target range: 3.0-4.0 International Normalised Ratio (INR), (b) low dose aspirin or (c) combined therapy of low dose aspirin and adjusted low intensity oral anticoagulation (target range INR: 2.0-2.5). It is planned to enroll 8,700 patients within three years. During an estimated mean follow-up of 2.5 years the evolutions of total mortality, non-fatal myocardial infarction, non-fatal stroke and major bleeding complication will be assessed.

To evaluate the incidence and treatment results of osteosarcoma of the jaw (OSJ) in the Netherlands, data from 48 patients with a histologically proven diagnosis of osteogenic sarcoma of the maxilla or mandible were retrospectively analysed. Patient files, covering the period from 1964 to 1992, were obtained from all university hospitals in the Netherlands and the Netherlands Cancer Institute. The incidence of OSJ in the Netherlands is estimated to be at least 0.14 per 1,000,000. The overall 10-year survival was 59%. Distant metastasis occurred in 21% and local recurrences in 31% of the cases. Survival was significantly better in case of radical surgery and small tumours. Long-term survival after treatment of OSJ was good if complete surgical excision was achieved. Radiotherapy should only be considered to prevent local recurrence if surgery is not complete. The possible benefit of current chemotherapy in preventing metastatic disease is still questionable. Since other malignant neoplasms associated with OSJ occurred in 17% of the cases, lifelong follow up is mandatory for the detection of these second primary malignancies.

Objective: To establish whether histopathologic variables other than the pathologist's statement of complete excision predict recurrence of squamous cell carcinoma at the primary site and therefore indicate local postoperative radiotherapy., Design: Retrospective analysis of clinical data and review of slides of resection specimens., Setting: Tertiary care, hospital-based clinic., Patients: Eighty-two patients who had complete excision only (histologically based) of a T1 or T2 squamous cell carcinoma of the mobile tongue or floor of the mouth but did not receive any form of immediate postoperative radiotherapy. Twenty-nine patients underwent local resection without treatment of the NO neck; in 53 patients a neck dissection was also performed., Methods: Evaluation of recurrent tumor above the clavicles until 4 years postoperatively and of second and third primaries. Infiltrative depth was evaluated in 73 cases and spidery spread, perineural spread, and angioinvasion in 70 cases., Results: Of the squamous cell carcinoma, 27% were well differentiated and 73% were moderately differentiated; depth of invasion was 5 mm or more in 57%, a spidery growth pattern was present in 51%, there was perineural spread in 16%, and angioinvasion was found in 3%. Recurrences at the primary site, not linked to histopathologic findings, occurred in 4%; 17% of the patients had second primary tumors in the head and neck region, 15% had neck conversions, and 1% had neck recurrence., Conclusions: When excision of a small squamous cell carcinoma of the mobile tongue or the floor of the mouth is histologically complete, other histopathologic variables are irrelevant in predicting recurrence at the primary site, and local radiotherapy is not indicated, considering the morbidity and high number of second and third primary tumors to be expected that will require future new treatment.

Acquired resistance to both Onchocerca volvulus and O. lienalis infective larvae, implanted within micropore chambers, could be induced in mice following immunization with irradiated L3 larvae. In experiments with O. volvulus in BALB/c and BALB/c. By mice, consistent levels of protection (61-75% reductions compared to challenge controls) were achieved with challenge infections of 2 week duration. In DBA/2 mice, levels of protection against O. lienalis were lower and more variable (42-63%): Moreover a 3 week period between challenge and recovery was required before significant reductions in larval recovery became detectable in vaccinated animals. Immunization of CBA or BALB/c mice with O. lienalis microfilariae, or CBA mice with normal or irradiated O. lienalis L3 larvae, failed to induce killing or growth retardation of developing larvae. Preliminary characterization of the effector mechanisms and cytokines associated with protective immunity against O. volvulus infective larvae revealed elevated levels of eosinophils in peripheral blood and within micropore chambers during challenge infections in vaccinated mice. Spleen cells from the same animals stimulated with parasite antigen induced significant levels of IL-5, IL-4 and IFN gamma. These cytokines were barely detectable in antigen stimulated cells from challenge control mice.