The effect of physical treatment on the induction of heterotopic bone formation by demineralized dentin in guinea pigs

Abstract. A total of 388 allogenic demineralized guinea pig dentin samples, excluding 54 controls, were exposed to ionizing irradiation, ultrasonic vibration, heat, or storage at different temperatures. They were then subjected to amino acid analyses or transmission electron microscopy or implanted in the abdominal muscle of 74 male guinea pigs for four or five weeks. With increasing exposure to irradiation, heat or ultrasonic vibration, there was a decrease in the capacity of the implants to induce bone formation. This was most marked for the implants that had been subjected to 10.0 million rad or high temperature. Implants stored for more than approximately 8–12 weeks seemed to lose some of their bone-inducing capacity, especially if stored at room temperature. Irradiation and heating resulted in profound changes in the dentin ultrastructure with swelling of the collagen fibrils and loss of cross-striation. Specimens subjected to ultrasonic vibration showed some cleft formation in the dentin matrix but the collagen fibrils had retained cross-striation. While irradiation caused a slight increase in acetic acid extractability of the dentin matrix, ultrasonic vibration and heating did not. It is suggested that the bone inducing capacity of dentin matrix is related lo a non-collagenous protein.     

Induction of heterotopic bone formation by demineralized dentin in guinea pigs: antigenicity of the dentin matrix

Abstract. Fifty autogenous, 120 allogenic and 40 xenogenic demineralized dentin specimens as-well as 36 undemineralized allogenic specimens were implanted in the abdominal muscles of 74 male guinea pigs for periods ranging from 4 to 12 weeks. An experimental model for the first and second set reaction in allogenic ear skin grafts was established in 10 male guinea pigs. The mean survival times of the first and second sets of these grafts were 10.1 days, s.d. = 1.57 and 5.2 days, s.d. = 0.78, respectively. Repeated implantation of both undemineralized, and demineralized and lyophilized allogenic dentin evoked an immune response in the host resulting in an accelerated skin graft rejection. Furthermore, in the second and third sets of implants the bone inducing process was either prevented (undemineralized dentin) or reduced (demineralized and lyophilized dentin). Xenogenic demineralized dentin failed to induce osteogenesis, probably due to an intense host immune response. The first set of allogenic demineralized dentin implants, on the other hand, induced bone formation in a high percentage of cases, it even gave the impression of enhancing the induction process compared to autogenous dentin.     

Cephalometric analysis in patients with obstructive sleep apnoea syndrome. I. Skeletal morphology

Facial skeletal morphology was studied by cephalometric analysis in 25 patients with obstructive sleep apnoea syndrome (OSAS) and ten controls. The hyoid bone was more inferiorly positioned in patients (at the level of cervical vertebrae C4-C6) than in controls (C3-C4 level). The height and length of the nasal cavity was normal, while the length of the bony nasopharynx was moderately reduced. The mandibular plane inclination was slightly larger in patients as was the anterior face height. Mandibular retrognathia was demonstrated in six patients (24 per cent), but the angles of maxillary and mandibular prognathism was within normal limits when the group was considered as a unity. Cephalometric analysis is highly recommended as a diagnostic aid in OSAS patients, especially when surgical intervention is considered.     

Effect of human fibrin adhesive on the ear. An electrophysiological study of auditory function in the guinea pig correlated to light and electron microscopy of middle ear mucosa and inner ear structures

The effect of human fibrin adhesive applied to the middle ear has been studied in guinea pig. Auditory function was measured using acoustically evoked brainstem responses. Middle and inner ear structures were studied with light, transmission and scanning electron microscopy. A transitory conductive hearing loss was observed, but after 8 weeks the auditory function appeared normal. Microscopy of the middle and inner ear failed to show any tissue damage.     

Impedance changes elicited by tactile and electrocutaneous stimulation

In each of 24 randomly selected outpatient the size of the impedance changes elicited by touching the skin in the ipsilateral cavum conchae with cotton wool were compared with those elicited by electrical stimulation of the same skin area. Pulse trains of 0.5 s duration, consisting of individual squarewave constant current pulses of frequency 200 Hz and duration 1 ms, were used. In all ears a current of 0.5-1 mA produced impedance change of about the same size as the tactile stimulus. Therefore, in testing the middle ear function observation of impedance changes elicited by tactile as well as electrical stimulation can be used. Electrical stimulation, however, has the following advantages: 1) Artifacts produced by accidently touching the probe tip are avoided. 2) The electrical stimulus is well defined and reproducible.     

Nasal obstruction in children with craniofacial malformations

The etiology, patient evaluation and management of nasal obstruction in children with craniofacial malformations is broadly discussed. Specific reference is made to the experience by the senior author (WSC) with respect to nasal surgery in 29 of these patients during the 12 years from 1987 to January 1st, 1998.     

Prevalence of Anti-SARS-CoV-2 Antibodies and Potential Determinants among the Belgian Adult Population: Baseline Results of a Prospective Cohort Study

The prevalence of anti-SARS-CoV-2 antibodies and potential determinants were assessed in a random sample representative of the Belgian adult population. In total, 14,201 individuals (≥18 years) were invited by mail to provide saliva via an Oracol^® swab. Survey weights were applied, and potential determinants were estimated using multivariable logistic regressions. Between March and August 2021, 2767 individuals participated in the first data collection. During this period, which coincided with the onset of the vaccination campaign, the seroprevalence in the population increased from 25.2% in March/April to 78.1% in July. Among the vaccinated there was an increase from 74,2% to 98.8%; among the unvaccinated, the seroprevalence remained stable (around 17%). Among the vaccinated, factors significantly associated with the presence of antibodies were: having at least one chronic disease (OR_a 0.22 (95% CI 0.08–0.62)), having received an mRNA-type vaccine (OR_a 5.38 (95% CI 1.72–16.80)), and having received an influenza vaccine in 2020–2021 (OR_a 3.79 (95% CI 1.30–11.07)). Among the unvaccinated, having a non-O blood type (OR_a 2.00 (95% CI 1.09–3.67)) and having one or more positive COVID-19 tests (OR_a 11.04 (95% CI 4.69–26.02)) were significantly associated. This study provides a better understanding of vaccine- and/or natural-induced presence of anti-SARS-CoV-2 antibodies and factors that are associated with this presence.