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Biomedical subjects

C D Verwoerd

Publications and source records attributed to C D Verwoerd.

At least 19 recordsLinked to original sources
PubMed2001

A new in vivo model for testing cartilage grafts and biomaterials: the 'rabbit pinna punch-hole' model.

In this study an animal model was developed for evaluation of the feasibility of cartilage grafts. In the cartilage of the external ear of the rabbit multiple holes, 6 mm in diameter, were punched, leaving the adherent skin intact. Different experimental groups were evaluated. First, the punch-hole model was validated under various conditions to study spontaneous or perichondrial initiated regeneration of the cartilage defect. When both cartilage and perichondrium was excised no spontaneous repair of the cartilage defect was observed. When perichondrium is present, variable patch-like closure of the punch hole was found. As 'golden standard' a punched out piece of cartilage was reimplanted directly. This condition showed adequate closure of the punch hole, however, no perfect integration of graft and surrounding cartilage was observed. Secondly, to evaluate the 'punch-hole model' a biomaterial, trabecular demineralized bovine bone matrix (DBM), was implanted and tested as a scaffold for tissue engineering techniques in vivo and in vitro. Direct implantation of DBM did not lead to any cartilage formation to close the defect. In vivo engineered cartilage, generated by enveloping DBM in perichondrium for 3 weeks, could adequately close the punch hole. When DBM was seeded with isolated chondrocytes in vitro before implantation in the defect, a highly fragmented graft, with some islets of viable cells was seen. To promote an efficient and reliable evaluation of cartilage grafts a semi-quantitative grading system was developed. Items such as quality, quantity and integrity of the cartilage graft were included in a histomorphological grading system to provide information about the properties of a specific cartilage graft. To validate the grading system, all conditions were scored by two independent observers. An excellent reliability (R = 0.96) was seen between the observers. In summary, the rabbit pinna punch-hole model is a reliable and efficient method for first evaluation of cartilage grafts. The results can be easily analyzed using a semi-quantitative grading system.

Animals↗
PubMed1999

Pediatric otorhinolaryngology in Europe.

Nowadays Europe encompasses more than 30 countries. These countries differ in climate, in culture, in population density, in history, in socio-economic system and in the organization of medical care. Despite these differences there is a general trend of unification in politics, in industry and in science. In the field of medicine, medical faculties and professional organizations try to harmonize medical curricula and training programmes for medical specialists.

Child↗
PubMed1998

Psychosocial and physical correlates of survival and recurrence in patients with head and neck carcinoma: results of a 6-year longitudinal study.

BACKGROUND: Studies that have examined correlations between psychosocial factors and survival in cancer patients do not permit any definitive conclusions. To the authors' knowledge, to date no study has examined the relation between medical as well as quality of life variables and survival in head and neck carcinoma patients. The current study focused on the complex interactions among psychosocial, medical, behavioral, and demographic variables as they relate to prognosis in these patients. METHODS: A total of 133 consecutive head and neck carcinoma patients were included in a prospective study at pretreatment. In addition to clinical variables, psychosocial and physical functioning was assessed by means of a self-report questionnaire. RESULTS: During the observation period 57 patients died whereas 76 were still alive at 6 years after treatment. Results of the multivariate survival analysis indicated that patients without head and neck metastasis had a better prognosis than patients with positive cervical lymph nodes. Pretreatment smoking showed a negative correlation with overall survival. Patients who were more physically self-efficacious (i.e., higher perceived physical abilities) were more likely to survive and less likely to develop a recurrence. In addition, patients who expressed intense psychosocial complaints prior to treatment had a better prognosis than had those who did not express such negative feelings. CONCLUSIONS: The current findings linking physical self-efficacy and prognosis are promising, but clinical trials are necessary to examine the direct and indirect mediational pathways of the variables that underlie physical efficacy and influence survival and recurrence. Also, the negative correlation between pretreatment smoking and survival suggests a need for increased efforts to address smoking in newly diagnosed patients.

Adult↗
PubMed1998

Wound healing of cartilage structures in the head and neck region.

This study was performed to determine the various processes involved in the behaviour of hyaline cartilage during the wound healing period after trauma or surgery of vulnerable structures like the nasal septal cartilage and the cricoid. The results of different procedures (perpendicular and parallel to the cartilage surface) in young and young-adult animals were analyzed: septal incision at different locations (young-old), cricoid split (young-old), suturing cartilage, closing defects with autologous cartilage (young), biomaterials (young) and newly engineered cartilage in 4- and 24-week-old rabbits (series of ten animals). Cartilage of the young rabbit and child have similar hyaline cartilage with a varying distribution in thickness. Thinner areas are more susceptible to malformations. Incisions through younger cartilage give rise to some new cartilage formation covered by a new layer of perichondrium: through older, differentiated cartilage the incision causes superficial but permanent necrosis. Edges of cut cartilage mostly do heal by formation of fibrous junctions. This forms a weak spot, sensitive to deviations. The same fate goes for the healing between the autologous graft and the surrounding pre-existent cartilage. Trauma parallel to the surface, leads to inconsistent quantity of neocartilage. With ageing the wound healing and regenerative capacities decrease. In general, biomaterials are less accepted by the surrounding tissues and would impede further growth. Only newly engineered, and thus less differentiated (younger) cartilage of hyaline nature, appeared to be well accepted at the interface with the edges of a cartilage defect. There are indications that the release of growth factors might play a role in cartilage wound healing. In the child as well as the adult, wound healing of hyaline cartilage structures is incomplete, and surgery remains 'experimental' surgery. The clinical implications of gradual loss of the regenerative capacity of hyaline cartilage should be further investigated.

Animals↗
PubMed1998

The immediate effects of local trauma on the shape of the cricoid cartilage.

Injury-induced abnormal development of the cricoid ring has been demonstrated in previous growth studies. In this study we focused on the immediate effects of various types of lesions to the cricoid, eliminating the influence of inserting muscles. In isolated, vital cricoids (cricoid explants) the anterior arch was split, creating a small gap between the cut ends. Previous injury to the internal surface of the cricoid ring resulted in a three to four fold increase of the diameter of the gap, actually widening the interrupted cricoid. On the contrary, injuring the external surface of the cricoid cartilage prior to anterior cricoid split, leads to an overlap of the cut edges, and a narrowing of the ring. These injury-specific changes in shape of the cricoid ring are ascribed to the release of interlocked stresses, present in the cartilage. It is suggested that the demonstrated methods to change the shape of the cricoid ring in a predictable way, are relevant for the treatment of patients with cricoid malformation.

Analysis of Variance↗
PubMed1998

Ultrasound in the diagnosis of cervical tuberculous adenitis.

Ultrasound (US) of cervical tuberculous adenitis (CTA) was demonstrated to produce a characteristic pattern of the affected nodes in the majority of the patients in this study. The contribution of US to the diagnosis and assessment of CTA is evaluated. It is concluded that, since the other diagnostic tests for CTA are not reliable and/or time-consuming, the demonstration of nodal calcifications, conglomerate nodal masses and spread into the subcutaneous tissues at US in patients with elusive cervical masses may result in earlier recognition of CTA.

Adult↗
PubMed1998

Efficacy of perichondrium and a trabecular demineralized bone matrix for generating cartilage.

A pedicled auricular perichondrial flap wrapped around trabecular demineralized bovine bone matrix can generate an autologous cartilage graft. In earlier experimental studies, it was demonstrated that this graft could be used for nasal and cricoid reconstruction. It was assumed that the vascularization of the perichondrial flap was obligatory, but it was never proven that the flap should be pedicled. Moreover, for clinical use, the dimensions of the auricle would set restrictions to the size of the graft generated. Therefore, the possibility to generate cartilage with a composite graft of a free perichondrial flap wrapped around demineralized bovine bone matrix, by using young New Zealand White rabbits, was studied. This composite graft was implanted at poorly (subcutaneously in the abdominal wall; n = 12), fairly (subcutaneously in the pinna; n = 12), and well-vascularized sites (quadriceps muscle; n = 12). As a control, trabecular demineralized bovine bone matrix was implanted without perichondrial cover. Half of these grafts (n = 6) were harvested after 3 weeks, and the remaining grafts (n = 6) after 6 weeks of implantation. In histologic sections of these grafts, the incidence of cartilage formation was scored. Furthermore, the amount of newly formed cartilage was calculated by computerized histomorphometry. Trabecular demineralized bovine bone matrix without perichondrial cover demonstrated early resorption; no cartilage or bone was formed. In demineralized bovine bone matrix wrapped in perichondrium, early cartilage formed after 3 weeks at well- and fairly vascularized sites. No cartilage could be detected in grafts placed at a poorly vascularized site after 3 weeks; minimal cartilage formed after 6 weeks. In summary, the highest incidence of cartilage formed when trabecular demineralized bovine bone matrix was wrapped either in a pedicled auricular perichondrial flap or in a free perichondrial flap, which was placed at a well-vascularized site. Second, a significantly higher percentage of the total area of the graft was cartilaginized at well-vascularized sites after 3 weeks. The newly generated cartilage contained collagen type II and proteoglycans with hyaluronic acid binding regions, whereas collagen type I was absent, indicating the presence of hyaline cartilage. This study demonstrates that new cartilage suitable for a graft can be generated by free perichondrial flaps, provided that the site of implantation is well vascularized. Consequently, the size of such a graft is no longer limited to the dimensions of the auricle.

Animals↗
PubMed1997

Management of infantile subglottic hemangioma: laser vaporization, submucous resection, intubation, or intralesional steroids?

The infantile subglottic hemangioma can be treated in various ways. The results of the treatment used in the Sophia Children's Hospital, intralesional steroids and intubation (IS + I), are discussed and compared with the results of other current treatment methods: CO2 laser vaporization, submucous resection and intubation alone. A total of 18 infants were treated for subglottic hemangioma in our hospital: ten with IS + I alone, five were first treated with systemic therapy and later with IS + I alone and three with various therapies. IS + I was effective in 14 of the 15 patients, one patient was lost from follow up. The remaining three infants were treated with (combinations of) various therapies, because IS + I failed or was not tried. Two patients were finally cured, one still has a tracheotomy. Of other current therapies, CO2 laser vaporization is reported to be effective. In all 30% of the infants treated in Boston Children's Hospital with CO2 laser needed a tracheotomy. Moreover subglottic stenosis is a serious complication. Submucous resection is often successful. It may be complicated by subglottic stenosis and in some cases, depending on the localization of the hemangioma, it may be contraindicated. Intubation alone is less effective than intubation combined with intralesional steroids. Management of subglottic hemangioma in Sophia Children's Hospital is primarily intralesional steroids and intubation and secondarily submucous resection or tracheotomy. CO2 laser vaporization is seldom applied because of the risk of subglottic stenosis.

Female↗
PubMed1997

Growth dynamics of the cricoid cartilage and subglottic injury. An autoradiographic and histometric study in the rabbit.

Earlier studies in young growing rabbits have suggested that post-traumatic developmental deformities of the cricoid might play a role in failing treatment in children with similar injuries. Specific patterns of malformations in the animals occurred preferentially at the anterior side of the cricoid ring. In this study, the growth dynamics of the cricoid were studied by histometry and autoradiography. Results indicated that (1) the cell/matrix ratio remains unchanged from 4 to 24 weeks of age, with both tissue components thus contributing equally to growth of the cricoid; (2) mitoses occur in cartilage and perichondrium, indicating interstitial as well as appositional growth; (3) mitotic activity is mainly restricted to the first 4 weeks of life, while cell hypertrophy is thereafter the dominant feature; (4) the highest degree of mitotic activity and cell hypertrophy is found in the anterior half of the cricoid ring which therefore can be considered as a growth center. This center might play a role in the development of trauma-induced deformation in the anterior part of the cricoid ring.

Aging↗
PubMed1996

Acquired laryngeal stenosis in infants and children treated by laryngofissure and stenting.

Thirty young patients with acquired laryngeal stenosis were treated by means of a laryngofissure and stenting. The age distribution suggested two subgroups: infants aged 0-2 years (n = 24), and children aged 6-16 years (n = 6). The causes of the stenosis and the treatment results were different in these subgroups. Treatment resulted in successful decannulation in 22 of 24 infants, and in 5 of 6 children. Treatment included a re-operation in two patients. In 1 patient the therapy failed, and 2 patients died after fatal complications. Decannulation rate, duration of the tracheotomy, and the number of re-operations compare favorably to the results of other centers. The longer duration of stenting, and the high mortality rate may be considered disadvantages.

Adolescent↗
PubMed1996

Growth characteristics of the human nasal septum.

Using a specially designed algorithm for the measurement of the surface area of shapes with highly irregular contours, growth curves were developed for post-natal septal growth in humans using post-mortem specimens of a study population of 30 cases, distributed over the age range from birth to 62 years. From the results a rapid growth phase for the total septum is evident immediately after birth, lasting until the second year of life. Then, a gradual deceleration of growth is recognized with a plateau eventually being reached at the age of 36 years. Mathematical analysis of the growth curve shows that the curve for the total septum is the sum of two separate mathematical equations, representing the cartilaginous and bony contribution, respectively. It is demonstrated that the cartilaginous septum reaches adult dimensions (lateral surface area) at the age of two years. Subsequent growth of the septum is due to expansion of the perpendicular plate, i.e. the bony parts of the septum.

Adolescent↗
PubMed1995

Therapeutic reintubation for post-intubation laryngotracheal injury in preterm infants.

The failure to extubate a preterm infant after prolonged intubation is often caused by laryngotracheal injury. This condition is treated by tracheotomy, anterior cricoid split, or often, by reintubation and subsequent extubation attempts in a later stage. To assess the value of reintubation as treatment of post-intubation injury, we retrospectively studied a group of preterm infants from the neonatal intensive care unit in the Sophia Children's Hospital. Three categories of injury were distinguished according to the findings at laryngobronchoscopy: (a) edema or superficial lesions, (b) ulcerations and edema and (c) granulations. Twenty-three infants were therapeutically reintubated after post-intubation injury was diagnosed, for a mean period of 17 days. The therapy was successful in 22 patients, and a failure in one. The follow-up period was a mean 34 months. The result and the duration of the treatment vary with the category of the injury and the condition of the patient. Therapeutic reintubation is compared with alternatives such as anterior cricoid split and tracheotomy. We conclude that reintubation is a valuable therapy that should precede the decision for surgery.

Cricoid Cartilage↗
PubMed1995

Cartilage transformation in a composite graft of demineralized bovine bone matrix and ear perichondrium used in a child for the reconstruction of the nasal septum.

For the first time it was observed in a boy that a xenogenic implant of demineralized bovine bone matrix, enfolded in a pedicled flap of autogenic ear perichondrium, was transformed into autogenic cartilage. This new cartilage could be adequately used as a graft to bridge the cartilaginous defect of a nasal septum perforation. The defect was successfully closed by a technique employing four bipedicled mucosal advancement flaps of the septum and the nasal floor. The result of this pilot study, which is based on experiments in growing rabbits, appears to open the possibility to create de novo young and growing autogenic cartilage of substantial quantity in children, without the loss of the cartilage present.

Child↗
PubMed1995

The nose in children with unilateral cleft lip and palate.

Surgeons and orthodontists are still challenged to achieve 'better' noses for children with a unilateral cleft or lip, alveoulus and palate (UCLP). Various aspects are discussed: infant anatomy and later changes, developmental mechanics, cleft syndrome in animals with surgically produced facial clefts, untreated patients with congenital clefts, the radical primary correction of the UCLP nose, the unsolved problems in secondary rhinoplasty and suggestions for scientific communication.

Animals↗