A study of primary dental enamel from preterm and full-term children using light and scanning electron microscopy

Purpose: The aim of this study was to examine the enamel thickness of the maxillary primary incisors of preterm children with very low birth weight (< 1,500 g) compared to full-term children with normal birth weight. Methods: A total of 90 exfoliated maxillary primary central incisors were investigated using light microscopy and scanning electron microscopy (SEM). Three serial buccolingual ground sections of each tooth were examined under light microscopy, and maximum dimensions of the prenatally and postnatally formed enamel were measured. Results: The enamel of preterm teeth was approximately 20% thinner than that for fullterm teeth. Most of the reduction was observed in the prenatally formed enamel. This was 5 to 13 times thinner than that for full-term children (P < .001). The catch-up thickness of postnatally formed enamel did not compensate fully for the decrease in prenatal enamel (P < .001). Although none of the teeth used in this study had enamel defects visible to the naked eye, 52% of preterm teeth showed enamel hypoplasia under SEM, compared with only 16% found on full-term teeth (P < .001). These defects were present as pits or irregular, shallow areas of missing enamel. Conclusions: Preterm primary dental enamel is abnormal in surface quality, and is significantly thinner compared to full-term enamel. The thinner enamel is due mainly to reduced prenatal growth and results in smaller dimensions of the primary dentition.

Electrical impedance particle size method (Coulter Counter) detects the large fat globules in poorly homogenised UHT processed milk

The large fat globules that can be present in UHT milk due to inadequate homogenisation cause a cream layer to form that limits the shelf life of UHT milk. Four different particle size measurement techniques were used to measure the size of fat globules in poorly homogenised UHT milk processed in a UHT pilot plant. The thickness of the cream layer that formed during storage was negatively correlated with homogenisation pressure. It was positively correlated with the mass mean diameter and the percentage volume of particles between 1.5 and 2 mu m diameter, as determined by laser light scattering using the Malvern Mastersizer. Also, the thickness of the cream layer was positively correlated with the volume mode diameter and the percentage volume of particles between 1.5 and 2 mu m diameter, as determined by electrical impedance using the Coulter Counter. The cream layer thickness did not correlate significantly with the Coulter Counter measurements of volume mean diameter, or volume percentages of particles between 2 and 5 mu m or 5 and 10 mu m diameter. Spectroturbidimetry (Emulsion Quality Analyser) and light microscopy analyses were found to be unsuitable for assessing the size of the fat particles. This study suggests that the fat globule size distribution as determined by the electrical impedance method (Coulter Counter) is the most useful for determining the efficiency of homogenisation and therefore for predicting the stability of the fat emulsion in UHT milk during storage.

Molecular development of the olfactory nerve pathway

There are, at least, two major questions concerning the molecular development of the olfactory nerve pathway. First, what are the molecular cues responsible for guiding axons from the nasal cavity to the olfactory bulb? Second, what is the molecular basis of axon targeting to specific glomeruli once axons reach the olfactory bulb? Studies in the primary olfactory pathway have focused on the role of the extracellular matrix and ensheathing cells in establishing an initial substrate for growth of pioneer axons between the periphery and brain. The primary axons also express a multitude of cell adhesion molecules that regulate fasciculation of axons and hence may play a role in fascicle formation in the olfactory nerve. Although the olfactory neuroepithelium principally consists of a morphologically homogeneous class of primary olfactory neurons, there are numerous subpopulations of olfactory neurons expressing chemically distinct phenotypes. In particular, numerous subpopulations have been characterized by expression of unique carbohydrate residues and olfactory receptor proteins. Some of these molecules have recently been implicated in axon guidance and targeting to specific glomeruli.

Trial-of-antibiotic algorithm for the diagnosis of tuberculosis in a district hospital in a developing country with high HIV prevalence

OBJECTIVE: To evaluate a diagnostic algorithm for pulmonary tuberculosis based on smear microscopy and objective response to trial of antibiotics. SETTING: Adult medical wards, Hlabisa Hospital, South Africa, 1996-1997. METHODS: Adults with chronic chest symptoms and abnormal chest X-ray had sputum examined for Ziehl-Neelsen stained acid-fast bacilli by light microscopy. Those with negative smears were treated with amoxycillin for 5 days and assessed. Those who had not improved were treated with erythromycin for 5 days and reassessed. Response was compared with mycobacterial culture. RESULTS: Of 280 suspects who completed the diagnostic pathway, 160 (57%) had a positive smear, 46 (17%) responded to amoxycillin, 34 (12%) responded to erythromycin and 40 (14%) were treated as smear-negative tuberculosis. The sensitivity (89%) and specificity (84%) of the full algorithm for culture-positive tuberculosis were high. However, 11 patients (positive predictive value [PPV] 95%) were incorrectly diagnosed with tuberculosis, and 24 cases of tuberculosis (negative predictive value [NPV] 70%) were not identified. NPV improved to 75% when anaemia was included as a predictor. Algorithm performance was independent of human immunodeficiency virus status. CONCLUSION: Sputum smear microscopy plus trial of antibiotic algorithm among a selected group of tuberculosis suspects may increase diagnostic accuracy in district hospitals in developing countries.

Tetraphyllidean metacestodes of teleosts of the Great Barrier Reef, and the use of in vitro cultivation to identify them

The tetraphyllidean metacestode diversity of 310 teleost fishes, including 87 species from 31 families, was examined from Heron Island, The Great Barrier Reef, Australia. Eleven metacestode 'types' were identified with the use of light microscopy. Host-specificity varied greatly among metacestode types. Incorporation of in vitro cultivation allowed generic identification for some types. Types 1 and 2 belong to Uncibilocularis Southwell, 1925, and have triloculate bothridia and one pair of Forked hooks with unequal prongs; Type 3 has quadriloculate bothridia. Hook development was insufficient to determine in which genus, Acanthobothrium van Beneden, 1849 or Calliobothrium van Beneden, 1850, this type may belong. Type 4 has unilocular bothridia with simple edges and belongs to Anthobothrium van Beneden, 1850. Type 5 has multiloculated bothridia which are invaginated within pouches. This type belongs to the Rhinebothriinae although its generic identity cannot be determined. The bothridia of Type 5 everted within 24 hours of in vitro cultivation and revealed the presence of two forms, one having 48 loculi per bothridium, the other 72 per bothridium. In vitro studies provide additional support for existing theories of onchobothriid scolex development.

Sheina orri (Myodocopa: Cypridinidae), an ostracod parasitic on the gills of the epaulette shark, Hemiscyllium ocellatum (Elasmobranchii: Hemiscyllidae)

The cypridinid ostracod, Sheina orri, was found on the gills of healthy epaulette sharks, Hemiscyllium, ocellatum, collected from the Great Barrier Reef, Australia, Seventeen of the 28 fish examined had ostracods attached to their gills. Detailed investigation of the gills and ostracods using light microscopy and scanning electron microscopy revealed that ostracods anchor themselves to the gill tissues using their mandibular and maxillular claws. These claws appear to be adapted for this purpose and the process of attachment causes some damage to the host tissues. The observation that ostracods were often located in distinct pockets, formed by local distortion of shark respiratory lamellae, strongly suggests that they had been attached to the gills for considerable time. (C) 1997 Australian Society for Parasitology.

Variations in cone photoreceptor abundance and the visual ecology of birds

The relative abundance and topographical distribution of retinal cone photoreceptors was measured in 19 bird species to identify possible correlations between photoreceptor complement and visual ecology. In contrast to previous studies, all five types of cone photoreceptor were distinguished, using bright field and epifluorescent light microscopy, in four retinal quadrants. Land birds tended to show either posterior dorsal to anterior ventral or anterior dorsal to posterior ventral gradients in cone photoreceptor distribution, fundus coloration and oil droplet pigmentation across the retina. Marine birds tended to show dorsal to ventral gradients instead. Statistical analyses showed that the proportions of the different cone types varied significantly across the retinae of all species investigated. Cluster analysis was performed on the data to identify groups or clusters of species on the basis of their oil droplet complement. Using the absolute percentages of each oil droplet type in each quadrant for the analysis produced clusters that tended to reflect phylogenetic relatedness between species rather than similarities in their visual ecology. Repeating the analysis after subtracting the mean percentage of a given oil droplet type across the whole retina (the 'eye mean') from the percentage of that oil droplet type in each quadrant, i.e. to give a measure of the variation about the mean, resulted in clusters that reflected diet, feeding behaviour and habitat to a greater extent than phylogeny.

Dental erosion in asthma: A case-control study from south east Queensland

Background: Asthma medication places patients at risk of dental erosion by reducing salivary protection against extrinsic or intrinsic acids. But patterns of lesions in asthmatics may differ from patterns in non-asthmatics, because gastro-oesophageal reflux (GOR) is found in 60 per cent of asthmatics. Methods: The lesions in 44 asthma cases were compared to those of age and sex match controls with no history of asthma or medications drawn from the dental records of 423 patients referred concerning excessive tooth wear. The subjects were 70 males age range 15 to 55 years and 18 females age range 18 to 45. Anamnestic clinical data were compared between the two groups. Models of all 88 subjects were examined by light microscopy, and wear patterns were recorded on permanent central incisor, canine, premolar and first molar teeth. Results: Clinical differences were a higher incidence of tooth hypersensitivity; xerostomia, salivary gland abnormalities, gastric complaints, and self induced vomiting in the cases. No differences were found between the cases and controls on citrus fruit and acid soft drink consumption. More occlusal erosion sites were found in cases, whereas more attrition sites were found in the controls. There were no significant differences in palatal erosion on maxillary anterior teeth found between cases and controls. Lingual erosion of the mandibular incisors, found only in GOR patients, was not observed. Conclusions: A higher incidence of erosion was found in asthmatics. Gastro-oesophageal reflux symptoms were not associated with the sign of lingual mandibular incisor erosion. The clinical significance is that asthmatics are at risk of dental erosion from extrinsic acid, but GOR does not appear to contribute in a site-specific manner.

Macrophages, myofibroblasts and neointimal hyperplasia after coronary artery injury and repair

Macrophages participate in the restenosis process through the release of cytokines, metalloproteinases and growth factors. Studies of peritoneal granulation tissue suggest that macrophages may be precursors of myofibroblasts. This study examined the contribution of monocyte/macrophage lineage cells to neointimal cellular mass in a porcine model of thermal vascular injury. Thermal coronary artery injury caused medial smooth muscle cell necrosis and transformation of the media into an extracellular matrix barrier. The neointimal hyperplasia that developed over the injury sites was evaluated by light microscopy, electron microscopy and immunohistochemistry. At day 3, blood monocytes were adhered to the vessel wall and infiltrated the fibrotic media. At day 14, 42 +/- 3.9% of neointimal cells had a monocytic nuclear morphology and expressed macrophage-specific antigen SWC3 (identified by monoclonal antibody DH59B). Moreover, 9.2+/-1.8% of neointimal cells co-expressed SWC3 and alpha-smooth muscle actin and had ultrastructural characteristics intermediate between macrophages and myofibroblasts. At day 28, 10.5 +/- 3.5%, of cells expressed SWC3 and 5.2+/-1.8% of cells co-expressed SWC3 and alpha-smooth muscle actin. This study indicates that hematopoietic cells of monocyte/macrophage lineage abundantly populate the neointima in the process of lesion formation and may be precursors of neointimal myofibroblasts after thermal vascular injury. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Endodontic sequelae of dental erosion

Background. The incidence of, pulp involvement in patients with excessive wear has not been extensively documented. Methods: Clinical, records of 448 patients with excessive tooth wear were reviewed and 52 cases (11.6 per cent) with near or frank pulp exposures or root canal treatments were found and their numbers and sites were tabulated. Light microscopy of study models was used to determine aetiology at each site of exposure as. attrition, erosion or abrasion, scanning electron microscopy (SEM) was performed on some individual teeth. Results: Forty sites of near exposure and 57 sites of frank exposures or root canal treatments were found, some cases had both types of exposure. The commonest sites exposed by erosion were the palatal surfaces of maxillary, and the incisal surfaces of mandibular anterior teeth. Posterior teeth were not commonly affected. Toothbrush abrasion had exacerbated softie lesions as shown by SEM. Conclusions: Endodontic sequelae were found in 11 per cent of tooth wear patients as late stages of dental erosion. Near and frank exposures of the pulp thus constitute a small but significant, problem for,the Australian dental profession's concern in the of the tooth wear cases.

Microscopic structure of opalescent and nonopalescent pecans

The ultrastructure of pecans was investigated using light microscopy, environmental scanning electron microscopy, scanning electron microscopy, and transmission electron microscopy. Specific methodology for the sample preparation of pecans for electron microscopy investigations was developed. Electron microscopy of the ultrastructure of opalescent (discoloration of the interior) and nonopalescent kernels revealed that cellular damage was occurring in opalescent kernels. The damage was due to cell wall and membrane rupture, which accounted for the release of oil throughout the kernel. This rupture is due to the lower level of calcium in the cell membranes of opalescent pecans, as shown by energy dispersive X-ray spectrometry, making them more susceptible to damage.

Resolution enhancement by subtraction of confocal signals taken at different pinhole sizes

Subtractive imaging in confocal fluorescence light microscopy is based on the subtraction of a suitably weighted widefield image from a confocal image. An approximation to a widefield image can be obtained by detection with an opened confocal pinhole. The subtraction of images enhances the resolution in-plane as well as along the optic axis. Due to the linearity of the approach, the effect of subtractive imaging in Fourier-space corresponds to a reduction of low spatial frequency contributions leading to a relative enhancement of the high frequencies. Along the direction of the optic axis this also results in an improved sectioning. Image processing can achieve a similar effect. However, a 3D volume dataset must be acquired and processed, yielding a result essentially identical to subtractive imaging but superior in signal-to-noise ratio. The latter can be increased further with the technique of weighted averaging in Fourier-space. A comparison of 2D and 3D experimental data analysed with subtractive imaging, the equivalent Fourier-space processing of the confocal data only, and Fourier-space weighted averaging is presented. (C) 2003 Elsevier Ltd. All rights reserved.

Establishment and characterization of a new epithelial cell line, KC-1, from koala (Phascolarctos cinereus) conjunctiva

A novel, untransformed koala cell line (KC-1) was established by culturing koala conjunctival tissue in growth medium, which has permitted the study of the cell biology of this unique system. After the establishment of the KC-1 cell line, the cells were characterized by light microscopy, doubling time, and Western blot analysis. Light microscopy revealed that the cells have an epithelial morphology. Doubling times were significantly different (P < 0.015) depending on fetal calf serum (FCS) concentration (16.5 h in 10% FCS and 26.5 h in 2% FCS). Cells constricted while in suspension but were shown to attach to the coverslip (or flask) and flatten rapidly, less than 1 h after seeding. To confirm the epithelial nature of the cells, protein was extracted and Western blot analysis was performed. Subsequent probing with primary and secondary antibodies (monoclonal anticytokeratin clone C-11 IgG1 and anti-mouse IgG) revealed two bands at 45 and 52 kDa (compared against a protein molecular weight marker) that correspond to primary type I keratin and major type II keratin, respectively, expressed in simple epithelial cells. The koala cell line was adapted to grow continuously in Dulbecco modified Eagle medium containing 10% FCS for at least 30 passages. This unique cell line is an ideal toot for further investigation on koala cell biology and cytogenetics and for exploration of the pathophysiological mechanism of eye infections caused by different pathogens in koalas.

Ptychogyliauchen, a new genus of Gyliauchenidae (Platyhelminthes: Digenea) from siganid fishes of the Indo-West Pacific

We propose a new genus of the Gyliauchenidae Fukui, 1929 ( Digenea), Ptychogyliauchen, gen. nov., for four new species that infect Indo-West Pacific siganid fishes. Ptychogyliauchen, gen. nov. is a morphologically distinctive genus, diagnosed principally by the presence of a highly convoluted oesophagus, which generally exceeds the total body length of the worm, and by the unusual folded structure of the ejaculatory duct. Ptychogyliauchen thetidis, sp. nov. is designated as the type species, and is described from the intestine of Siganus punctatus (Siganidae) from Heron Island, Great Barrier Reef, Queensland, Australia. Ptychogyliauchen himinglaeva, sp. nov. is described from the intestine of Siganus corallinus ( Siganidae) from Lizard Island, Great Barrier Reef, Queensland, Australia. Ptychogyliauchen leucothea, sp. nov. is described from the intestine of S. argenteus, and further recorded from S. fuscescens, off Ningaloo, Western Australia, Australia. Ptychogyliauchen thistilbardi, sp. nov. is described from the intestine of S. doliatus from Noumea, New Caledonia, and is also found in S. argenteus, S. canaliculatus, S. corallinus and S. spinus from Noumea, New Caledonia, and Moorea, Tahiti, French Pacific. Ptychogyliauchen thistilbardi, sp. nov. also occurs in the intestine of Chaetodon citrinellus (Chaetodontidae) from Moorea. A key to species is provided. All species have been described following morphological examination using light microscopy, and specimens of P. thetidis, sp. nov., P. leucothea, sp. nov. and P. thistilbardi, sp. nov. have been characterised using molecular methods. Sequences were obtained for a combination of nuclear ribosomal (28S (D1-D3) and ITS2) and mitochondrial (ND1) genes. A phylogenetic analysis of sequenced specimens of Ptychogyliauchen, gen. nov. was conducted using species of Petalocotyle Ozaki, 1934 for outgroup comparison. This analysis, based on alignments of the ITS2 and 28S (D1-D3) rDNA genes, supports monophyly of the geographically widespread P. thistilbardi, sp. nov., which is known from both siganid and chaetodontid hosts. We discuss the taxonomy of the genus and the host associations of each species and the group.