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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
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↗
PubMed1984

Comparative studies on the localization of esteroproteases and kallikrein-like activity in primate organs.

Various organs of three species of monkey were screened histochemically for esteroproteases using N-acethyl-L-methionine-alpha-naphthylester (alpha N-O-met) as the substrate and also for enzymes with kallikrein-like activity using D-Val-Leu-Arg-4-methoxy-2-naphthylamide as the substrate. Characteristic differences were found in the localization of the reaction products obtained with both substrates. In the main salivary glands, esteroproteases (alpha N-O-met reactivity) were found in mucous cells (submandibular gland), intercalated duct cells (parotid gland), acinar cells (sublingual gland), striated and interlobular duct cells (all glands). They were also localized in superficial lining epithelial cells of the digestive system, in liver cells, and acinar cells of the pancreas. Enzymes with kallikrein-like activity were found only in the striated and interlobular duct cells of salivary glands, in acinar cells of the pancreas, and in proximal tubular cells of the kidney. Free cells (including mast cells) normally distributed in the connective tissue of various organs showed reactivity towards alpha N-O-met. Some of these cells were also reactive against Val-Leu-Arg-4-MNA.

Animals↗
PubMed1983

A 4-methoxy-2-naphthylamide substrate for the histochemical localization of esteroproteases in the submandibular gland of the rat.

The 4-methoxynaphthylamide (MNA) derivative of D-Val-Leu-Arg-4-MNA has been used as a substrate for the histochemical localization of esteroproteases in the submandibular gland of rats, and compared with the substrate alpha N-O-met. The hydrolysis of Val-Leu-Arg-4-MNA by esteroproteases was investigated using spectrophotometry and isoelectric focusing. Both methods demonstrated that the substrate is cleaved by different enzymes and is not a monospecific kallikrein marker, although Val-Leu-Arg-4-MNA had a much smaller spectrum of enzyme activities than alpha N-O-met. The activity against Val-Leu-Arg-4-MNA was totally inhibited by aprotinin but only partly by soybean trypsin inhibitor. A comparison of the histochemical localization of esteroproteases given by the substrate with the immunofluorescence localization of kallikrein showed that all the enzymes that hydrolysed Val-Leu-Arg-4-MNA and kallikrein were present in the same tissue structures.

Animals↗