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Biomedical subjects

W H Arnold

Publications and source records attributed to W H Arnold.

At least 19 recordsLinked to original sources
PubMed2005

Morphology of the auditory tube and palatal muscles in a case of bilateral cleft palate.

OBJECTIVE: There is an increased incidence of otitis media in children with cleft palate, which may be related to the pathology of the auditory tube and palatal muscles. In the present study, the head of a human on term born fetus with bilateral palatal cleft was serially sectioned and the anatomy of the auditory tube and palatal muscles were studied by computer-aided three-dimensional reconstruction. RESULTS: The results showed a nearly horizontal course of the auditory tube. The tensor veli palatini muscle had a bony attachment on either side. The levator veli palatini muscle also showed an abnormal course. CONCLUSIONS: This abnormal course may result in obstruction of the auditory tube during contraction. These pathological findings may explain the higher frequency of otitis media in children with cleft palate.

Anatomy, Cross-Sectional↗
PubMed2004

3D reconstruction of the cardiovascular and central nervous system of a human embryo Carnegie-stage 15--case report.

A human embryo at Carnegie stage 15 was serially sectioned and 3D computer aided reconstructions were made to demonstrate the cardiovascular system and cranial structures and to study developmental variations at this stage. The development of the heart and pharyngeal arteries was according to the existing literature. Differences were found in the development of the arterial circle of Willis and the central nervous system. The cranial venous system seemed to show great variability. Whereas the telencephalon was not developed according to the stage, the development of the hypophysis had occurred prior to stage 15. From the results we conclude that there are remarkable individual differences in embryological differentiation of structures which have to be taken into account during staging of human embryos.

Abortion, Spontaneous↗
PubMed2004

Development of the palatal size in Pan troglodytes, Hominids and Homo sapiens.

As the hard palate plays an important role in speech production it was the aim of this study whether similarities or dissimilarities in palatal size may allow conclusions about the ability to produce speech in the extant investigated species. The palatal size of Pan troglodytes, Homo sapiens, Australopithecus afarensis, Australopithecus africanus, Australopithecus robustus, Australopithecus boisei, Homo erectus, Homo neanderthalensis and Cro-Magnon has been investigated using euclidian distance matrix analysis (EDMA) and thin-plate-spline analysis. The results show that the palatal size of all australopithecine specimens and H. erectus is very similar to that of P toglodytes, whereas the palatal size of H. neanderthalensis more closely resembles that of H. sapiens. Postnatal development of palatal size in P troglodytes is different from that of H. sapiens. In P troglodytes not only the size of the palate changes but also the form. In H. sapiens there is little change in form, but a continuos uniform growth from infantile to adult specimens. From the results we conclude that in all australopithecine samples which have been investigated, the palatal size is similar to that of P troglodytes. Therefore, it is unlikely that austraopithecine individuals were capable of producing vowels and consonants. The palatal size of H. neandethalensis and Cro-Magnon is similar to that of H. sapiens which may indicate the possibility that they were capable of speech production.

Animals↗
PubMed2003

Volumetric assessment and quantitative element analysis of the effect of fluoridated milk on enamel demineralization.

OBJECTIVES: It was the purpose of this study to investigate the effect of milk and fluoridated milk on experimentally induced caries-like-lesions. MATERIALS AND METHODS: Twelve extracted impacted human molars were covered with wax leaving two 3 mm x 3 mm windows on the buccal and lingual surfaces and incubated alternating in demineralizing solution at pH 4.85 and in milk, F-milk, saline, and remineralizing solution, respectively. Afterwards serial ground sections were cut and investigated by polarization-light-microscopy (PLM) and SEM using EDX element analysis. RESULTS: The results showed increased thickness of the superficial layer in the F-milk samples. Quantitative element analysis revealed a significant increase in the fluoride content of the superficial layer and of the body of the lesion of the F-milk group. The body of the lesion of the F-milk group was less demineralized than in the other groups. CONCLUSION: From the results we conclude, that the parallel investigation by PLM, SEM combined with EDX quantitative element analysis is a powerful method to assess caries-like-lesion formation and that fluoridated milk has protective properties in inhibiting demineralization.

Animals↗
PubMed2003

Morphological analysis and chemical content of natural dentin carious lesion zones.

Dentin is one of the earliest bio-mineralization products to appear in the evolution of vertebrates. Dentin reactions to infection mimic earlier phylogenetic patterns, and carious lesions are divided into different zones which reflect the natural patho-morphological reaction of dentin to the carious attack. It was the aim of this study to investigate deep dentin carious lesions of human molars with combined polarization light microscopy, scanning electron microscopy and energy dispersive X-ray element analysis (EDX) for the determination of different zones of the carious lesions, their extent and the chemical content. Sixteen extracted teeth with deep dentin carious lesions were embedded in Technovit 9100 (Kulzer) and serial sections of 80 microm thickness were made. These sections were then examined with polarized light microscopy to identify the different zones of the lesions. The outlines of the zones were traced consecutively and 3D-reconstructions were made for the determination of the extent and calculation of the volumes of the different zones. From the volumes of the demineralizing dentin and the translucent zone a Dentin Demineralization Index (DDI) was calculated. Three sections of each lesion were then coated with carbon and studied with a scanning electron microscope. 3D-reconstruction of the teeth showed the rather stable translucent zone, interrupted by remnants of dead tracts, and very different volumes of demineralizing dentin. Therefore, with increasing size of the demineralizing dentin, the DDI increased. The chemical content was measured using energy dispersive X-ray analysis (EDX) in areas of intertubular dentin. The content of Ca, P, and C was significantly different in all zones. The Ca/P ratio was significantly different between sound dentin and demineralizing dentin. From the results we conclude that the mineral content of intertubular dentin of the translucent zone and demineralizing dentin is different from that of sound dentin, and the unique mineralization pattern of the translucent zone is a biological reaction to the carious attack. Because active dentin lesions exhibit many non-occluded open dentin tubules, further bacterial invasion or, in case of dentin treatment, the penetration of bonding agents towards the pulp is morphologically not prevented and therefore of clinical importance.

Dental Caries↗
PubMed2001

Qualitative and quantitative assessment of intratubular dentin formation in human natural carious lesions.

It was the aim of this study to investigate the scanning electron microscopy (SEM) features and the element content of calcium (Ca) phosphorus (P), magnesium (Mg), oxygen (O), and carbon (C) of sound dentin, demineralized dentin, secondary dentin, intratubular and peritubular de novo dentin formation due to caries progression and to compare the element content with chemically pure hydroxyapatite. Eighteen extracted teeth with deep dentin carious lesions were embedded in Technovit 9100 (Kulzer), and serial sections of 80 microm thickness were made. These sections were then investigated with polarized light microscopy to identify the lesions. Two sections of each lesion were then coated with carbon and studied with a scanning electron microscope. Of the 18 teeth, 8 showed intratubular dentin formation. The element content was measured using energy dispersive X-ray analysis (EDX). About 75% of all involved dentin tubules showed intratubular de novo dentin formation. The Ca/P ratio in sound dentin, demineralized dentin, peritubular dentin, and secondary dentin was within the range of hydroxyapatite, whereas in intratubular dentin the Ca/P ratio was different than that of hydroxyapatite. The element content for Ca was statistically highly significantly different (P < 0.01) among sound dentin/intratubular dentin, sound dentin/peritubular dentin, and sound dentin/ secondary dentin, but not between sound dentin/ demineralized dentin and sound dentin/hydroxyapatite. For the other measured elements varying statistical differences were found. Our results indicate that intratubular dentin does not occlude the dentin tubules completely and mineralizes different than that of sound dentin and may therefore not be true hydroxyapatite.

Dental Caries↗
PubMed2001

[Experimental algesimetric study of the hypoalgesic effect of body acupuncture].

AIMS: The aim of the present study was to investigate whether body acupuncture is suitable to increase the pre-pain sensitivity threshold (PPST). METHODS: For this purpose, the PPST was algesimetrically determined after pulpal electric stimulation (baseline) in 24 patients with healthy frontal teeth. RESULTS AND DISCUSSION: After acupuncture at specific (test group) and unspecific sites (control group, placebo acupuncture), the shift of the PPST was registered. After stimulation of specific acupuncture sites, a mean increase of 110% of the PPST could be obtained. Stimulation at unspecific sites showed only an increase of the PPST of 30%. To which extent this pain reduction is due to a physiological effect on pain reception, or physical irritation, or suggestion could not be verified in this study. Also, the endorphin theory discussed in connection with acupuncture could neither be proved nor disproved. Further controlled clinical studies have to be carried out to prove under clinical conditions the positive results of this experimental algesimetric study.

Acupuncture Analgesia↗
PubMed2001

Development of the membranous labyrinth of human embryos and fetuses using computer aided 3D-reconstruction.

The last detailed description of the development of the inner ear membranous labyrinth goes back to Streeter in 1918. This investigation can be regarded to be of outstanding scientific value. However, at that time no staging system of human embryos existed. In this respect, Streeter's work is outdated. It was the aim of this study to reinvestigate the development of the membranous labyrinth in human embryos and fetuses of which the developmental stages have been determined according to the Carnegie staging system and to compare the results with the literature. Serial histologic sections in the coronal or frontal plane of the heads of human embryos and fetuses of different developmental stages were used for computer aided 3D-reconstruction of the membranous labyrinth. From the obtained results, it is concluded that the endolymphatic duct develops earlier than previously described in the literature. The induction of the differentiation of the endolymphatic duct does not correspond with the superficial ectoderm because the endolymphatic duct develops medial of the otic vesicle. The membranous labyrinth determines the form of the petrosal bone as early as in stage 19 (47-48 days post conception).

Ear, Inner↗
PubMed2001

3D-reconstruction of craniofacial structures of a human anencephalic fetus. Case report.

It was the purpose of this study to investigate the craniofacial bones, cartilages and major blood vessels of a human anencephalic fetus and to describe the malformations of these structures accompanying this developmental disruption. The head of a 16 week old human fetus with anencephaly was serially sectioned and the craniofacial bones, cartilages and major blood vessels were traced and reconstructed by 3D-computer technology. The sphenoidal, temporal and occipital bones showed severe malformations, whereas the bones of the facial cranium were normally developed. Both internal carotid arteries ended within the cerebro-vascular area with no further branches. The vertebral arteries also ended within the cerebro-vascular area. No arterial circle of Willis was developed. The notochord terminated normally in the sphenoid body. The observations indicate that the possible reason for this malformation was non-closure of the anterior neuropore of the neural tube. The normal termination of the notochord suggests that it had no influence on the pathogenesis of this malformation. The malformations of the temporal and occipital bones are contradictory to the hypothesis of Marin-Padilla (1991) that anencephaly is caused by a maldevelopment of the sphenoidal bone.

Abortion, Induced↗
PubMed2001

Induction and 3D reconstruction of caries-like lesions in an experimental dental plaque biofilm model.

The aim of this study was to examine an in vitro dental plaque model for volumetric assessment and 3D reconstruction of experimentally bacterial induced caries-like lesions. Twenty-three extracted, impacted human molars were coated with a varnish leaving a 3 x 3 mm window on the smooth surface. The teeth were coated with human saliva and Streptococcus sobrinus 6715 adhered onto the enamel via a sucrose dependent mechanism. The coated teeth were incubated for 1, 7, 14 and 28 days. At the end of each incubation period microhardness was measured on three sectioned teeth of each incubation period at the enamel surface and at 450 and 750 microm depth perpendicular to the enamel surface. The enamel surface was investigated by scanning electron microscopy (SEM) prior to embedding and serial sectioning of 12 other teeth. The serial sections were studied with polarization light microscopy to investigate subsurface demineralization. The outlines of the caries-like lesions were then traced consecutively on transparencies, digitized and three-dimensionally reconstructed to demonstrate the expansion of the lesion into enamel for volumetric assessment. Microhardness was significantly reduced on the enamel surface after 7, 14 and 28 days incubation. The SEM investigation showed a surface demineralization with dissolution of the prism cores after 28 days incubation. Polarization light microscopy demonstrated caries-like lesions with an irregular expansion into enamel. The results demonstrate that the described method produces caries-like lesions which can be used for further experimental studies regarding demineralization and remineralization processes.

Biofilms↗
PubMed2000

Distribution and volumetric assessment of initial approximal caries lesions in human premolars and permanent molars using computer-aided three-dimensional reconstruction.

Serial sections from 21 extracted premolars and permanent molars, divided into three age groups (group 1, 10-19 years; group 2, 20-39 years; group 3, 50-69 years.), were viewed by polarized light microscopy for reconstruction of the caries lesions. The volumes of the lesional body and the transparent zone, and the volumes of early dentinal lesions were calculated; and an enamel demineralization index (EDI) and an enamel-dentine demineralization index (EDDI), representing the volumetric ratio of the body of the lesion to the translucent zone, and the body of the lesion to the volume of the early dentinal lesion, respectively, were determined. The method showed that there are three typical sites of individual initial caries lesions at the approximal surface: within the contact area, in the subcontact area, and in the cervical area. Volumetric assessment demonstrated a larger volume of the body of the lesion in older teeth with a smaller volume of the translucent zone relative to the lesional body. From these results it can be concluded that there are usually more than one individual initial caries lesions at the approximal tooth surface. Calculation of demineralization indices demonstrated different features for small lesions with pronounced transparent zones and for large lesions with small transparent zones. The computer-assisted three-dimensional reconstruction technique and the volumetric assessment are of value in investigations of the micromorphology and progression of natural caries lesions in permanent teeth.

Adolescent↗
PubMed1998

Three-dimensional reconstruction of approximal subsurface caries lesions in deciduous molars.

The present study examines the three-dimensional (3D) morphology of early approximal subsurface enamel caries lesions and subjacent dentin reactions in deciduous molars. Twenty-three extracted primary molars were embedded in Technovit 9100 and serial sections were cut using a saw microtome. Forty approximal lesions were found and investigated using polarized light microscopy for the identification of the different zones of the caries lesion. These zones were then reconstructed three-dimensionally using computer-aided 3D reconstruction methods and the dimensions and volumes of the translucent zone, the body of the lesion, and the dentin lesion were calculated. The enamel demineralization index was defined as the ratio between the translucent zone and the body of the lesion, whereas the enamel-dentin demineralization index was defined as the volumetric ratio of the early dentin lesion to the body of the enamel lesion. The 3D reconstruction of the lesions showed extremely heterogeneous micromorphological features of zone profiles. In enamel lesions, the results demonstrated a decreasing enamel demineralization index with increasing size of the lesion, which indicates a high risk of further caries progression. The enamel-dentin demineralization index indicated, in 5 out of 17 dentin lesions, a high risk of further caries progression. Computer-assisted 3D reconstruction and volumetric assessment of initial caries lesions in deciduous molars represents a valuable methodology in pathogenesis studies, which may lead to a better clinical understanding of caries progression.

Dental Caries↗
PubMed1998

Cranio-facial skeletal development in three human synophthalmic holoprosencephalic fetuses.

In three human fetuses with synophthalmic holoprosencephaly (8, 14, 23 wks. p.c.) and two normal human fetuses (9 and 13 wks. p.c.) the anatomy of the cranial base, facial cranium and their relation to the notochord was studied using serial histological sections and computer aided three-dimensional reconstruction methods. Mesethmoidal cartilage differentiation was variably deficient in all three holoprosencephalic cases. The premaxillary bones were rudimentary with missing tooth buds. The development of the sphenoid bone was defective in two of the holoprosencephalic cases (8, 14 wks. p.c.). The notochord terminated normally within the sphenoid body in all investigated cases. Our results indicate that in holoprosencephaly there is a general defect in the midline cranial cartilage differentiation rostral to the notochord.

Abortion, Spontaneous↗
PubMed1998

Location and distribution of epithelial pearls and tooth buds in human fetuses with cleft lip and palate.

OBJECTIVE: The purpose of this study was to establish the location and distribution of epithelial pearls and tooth buds in cleft palate fetuses, relative to the time of palate fusion. DESIGN: The facial skeletal structures, dental laminae, tooth buds, and epithelial pearls were examined in seven spontaneously aborted human fetuses, of which five had unilateral or bilateral cleft lip and palate or cleft palate. The sectioned fetuses were reconstructed by 3D-computer technology. RESULTS: Epithelial pearls were found in four of the investigated cases, of which one was a control specimen. They were located at the margins of the palatal shelves. In the cleft lip and palate cases, the cleft was found in the premaxilla between the first and second incisor tooth. The premaxilla was found to be hypoplastic in both bilateral cleft lip and palate cases and was totally absent in the unilateral cleft lip and palate case. The maxilla was hypoplastic in one case with unilateral cleft lip and palate. In all other specimens, it was developed symmetrically. CONCLUSIONS: The results indicate that cleft lip and palate development may occur after the fusion of the frontonasal prominence with the maxillary prominence and the palatal shelves, as well as a nonfusion of the palatal shelves in the secondary palate.

Cleft Lip↗
PubMed1998

ABT-594 [(R)-5-(2-azetidinylmethoxy)-2-chloropyridine]: a novel, orally effective antinociceptive agent acting via neuronal nicotinic acetylcholine receptors: II. In vivo characterization.

The antinociceptive effects of ABT-594, a novel nicotinic acetylcholine receptor (nAChR) ligand, were examined in rats in models of acute thermal (hot box) and persistent chemical (formalin test) pain. Also, the effects of ABT-594 treatment on motor function and electroencephalogram (EEG) were determined. In the hot box and formalin test (i.e., phase 1 and 2), acute treatment with ABT-594 (0.03, 0.1 and 0.3 mumol/kg i.p.) produced significant dose-dependent antinociceptive effects. In the hot box, the efficacy of ABT-594 was maintained after a repeated dosing paradigm (5 days b.i.d.i.p.). ABT-594 was fully efficacious in the formalin test when administered before formalin, and also retained significant efficacy (0.3 mumol/kg i.p.) when administered after formalin injection. The antinociceptive effects of ABT-594 in the hot box and formalin tests were attenuated by pretreatment with the nAChR antagonist, mecamylamine, and in animals treated with the nAChR antagonist chlorisondamine, given centrally (10 micrograms/rat i.c.v. 5 days before), but not in animals pretreated with the opioid receptor antagonist, naltrexone. Acute treatment with ABT-594 produced an initial decrease in open-field locomotor activity, which was absent in animals dosed repeatedly (5 days b.i.d.) with ABT-594. Also, acute treatment with ABT-594 decreased body temperature and decreased the amount of time the animals could maintain balance in an edge-balance test. These effects were no longer present in animals dosed repeatedly with ABT-594. At antinociceptive doses, ABT-594 produced activation of free running EEG in contrast to the sedative-like effects of morphine. Full antinociceptive efficacy was maintained in both the hot box and formalin tests after oral administration, whereas the effects on motoric performance were attenuated. In conclusion, these data demonstrate that ABT-594 is a potent antinociceptive agent with full efficacy in models of acute and persistent pain and that these effects are mediated predominately by an action at central neuronal nAChRs. In addition, antinociceptive effects were maintained after repeated dosing, whereas effects of ABT-594 on motor and temperature measures were attenuated in animals treated repeatedly with ABT-594. Thus, compounds acting at nAChRs may represent a novel approach for the treatment of a variety of pain states.

Administration, Oral↗
PubMed1996

Anatomy of the circle of Willis in three cases of human fetal synophthalmic holoprosencephaly.

In three human fetuses with synophthalmic holoprosencephaly (8, 14, 23 weeks post conceptionem) the circle of Willis was studied using serial histological sections and computer aided three dimensional reconstruction methods. This structure was abnormal in all cases. In two cases the anterior communicating arteries were absent. In all cases the anterior cerebral arteries could not be found. One case showed an incomplete circle with no posterior communicating artery. The results indicate that the malformation of the circle of Willis reflects the malformation of the brain.

Anencephaly↗