bluuebunny/crossref_metadata_2025 huggingface dataset:
The replacement of Alnus glutinosa by Fraxinus excelsior during succession related to regenerative differences
Authors: Tapper Per‐Goran
Published: July 2006

Mechanisms of the replacement of one species by another during a primary succession were studied in the deciduous woodland of the outer archipelago of Stockholm Sweden where there are only two principal tree species Alnus glutmosa (alder) was most abundant close to the sea shore while the abundance of Fraxinus excelsion (ash) increased with increasing elevation above sea level which due to the isostatic land upheaval corresponds to increasing age of the site Regeneration of the two species followed in permanent plots, was different Alder did not regenerate from seeds in the woodland No seedling survived 3 yr even under conditions of thin eanopy and removed field‐layer. and most died within the first year In contrast survival of ash was 35% after 10 yr Annual height increments of the ash juveniles were < 8 mm under a closed eanopy but growth of the juveniles increased rapidly when a gap was opened out by a tree‐fall Thus ash in eontrast to alder possesses characters advantageous for regeneration in gaps which may explain the successive replacement of alder by ash in this woodland
Bat species richness and abundance in tropical rain forest fragments and in agricultural habitats at Los Tuxtlas, Mexico
Authors: Estrada Alejandro , Coates‐Estrada Rosamond , Meritt Dennis
Published: July 2006

Faced with the rapid and extensive conversion of tropical rain forests to pasture lands and agricultural fields and with the need to preserve the remaining mammalian fauna, it is imperative to determine how the different species that form the mammalian community have responded to the anthropogenic alterations of their natural habitats To provide data in this direction, we sampled bats m 45 forest islands, m 20 agricultural habitats representing five types of vegetation (cocoa, coffee, mixed, citrus and allspice), in four live‐fence sites and in four pasture sites at Los Tuxtlas, Veracruz, Mexico Sampling effort resulted in the capture of 2587 bats representing 35 species In forest habitats we detected 32 species We did not capture any bats at the four pasture sites, but the at the other agricultural habitats studied, we captured 38% of the bats and 77% of the species recorded Thirty‐four percent of the species recorded were present at the live‐fence habitats Isolating distance was an important variable influencing species richness in forests and in agricultural habitats Only 10% of the species recorded occurred m all the habitats studied, but 77% of the species occurred m a habitat other than ram forest Recaptures of bats indicated inter habitat movements in the fragmented landscape We discuss the conservation value for the bat fauna of agricultural islands of vegetation as elements reducing isolating distances among forest fragments
Germination ecology of the polycarpic grassland perennials Primula veris and Trollius europaeus
Authors: Milberg Per
Published: July 2006

The seed germination behaviour of Primula veris and Trollius europaeus, both perennial, polycarpic grassland plants was compared The species have similar‐sized seeds that are dormant at dispersal Seeds buried in soil and exhumed at regular intervals showed that for both species, primary seed dormancy was overcome by cold‐stratification Hence, their germination in the field should occur in spring, following dispersal, or later Seeds of P veris became dormant again in the late spring/early summer, and dormancy was broken again in the second winter Seeds of T europaeus did not exhibit such changes in dormancy

Seeds of P veris did not germinate in darkness This suggests that P veris can accumulate a persistent seed bank because buried seeds are prevented from germinating Trollius europaeus, on the other hand, germinated equally well in darkness and in light which suggests that seeds might germinate even when they are too deep in the soil for seedlings to emerge Two lines of evidence confirm this difference in seed bank behaviour (1) Primula veris was detected in the persistent seed bank of a grassland site, whereas T europaeus was not (n) After 16 months burial, 85% of the P veris seeds but only 8% of the T europaeus seeds remained viable
Global warming and egg size of birds
Authors: Jàrvinen A.
Published: July 2006

Global warming or climate change is known to have many effects on plants, but there has been relatively little research on global warming and animals, partly because too few long‐term studies have been carried out. In northern areas, mean temperature is believed to be rising, and indeed during the last decades mean spring temperatures in Finnish Lapland have increased. In 1975‐1993, mean air temperature during the main egg‐laying period of a pied flycatcher Ficedula hypoleuca population correlated positively and significantly with mean egg volume of that population. Since larger eggs enjoy improved hatching success, global warming may alter birds' reproductive strategies, because warmer weather may allow females to invest more resources in reproduction. This in turn may help birds rapidly conquer new areas when they become available and compensate for rising mortality rates to be expected elsewhere where warming means desiccation.
Simulated climate change: a field manipulation study of polar microarthropod community response to global warming
Authors: Kennedy Andrew D.
Published: July 2006

Passive cloches were deployed at three altitudinally distinct sites on Signy Island, maritime Antarctica, to investigate the effect of ameliorated thermal environment upon fellfield microarthropod communities Temperature was monitored at 1 5 m height, at ground surface level, and at 5 cm depth in cloche and control plots During summer (December ‐ March), cloches elevated monthly mean temperatures by up to 2 46°C at the soil surface and 2 20°C at 5 cm depth Integrated air temperatures over consecutive 10 d periods were up to 4 65°C wanner in cloches than controls During winter (April ‐ November), snow cover of the fellfield sites buffered temperature variation and reduced the treatment effect After eight years of these manipulations, sampling of the upper 50 mm of soil revealed consistently greater microarthropod populations within cloches than in controls (treatment effect p<0.05) Maximum difference occurred at high altitude where thermal amelioration was greatest (site effect p<0.05) Cloche populations of the numerically dominant collembolanCryptopygus antarcticusWillem contained an increased proportion of small (length < 750 μm) individuals No species new to Signy Island were recorded Relating these microarthropod populations to the ameliorated thermal environment suggests that Antarctic invertebrate communities may respond to global warming, as predicted by global circulation models, with an increase in abundance with little increase in diversity However, this response could be indirect, the intermediate controlling factor being the percentage cover of the soil surface by vegetation, itself a function of climate change
Behavioural responses to food addition by hedgehogs
Authors: Cassini Marcelo H. , Krebs John R.
Published: July 2006

We conducted a field experiment at a 4‐ha sports ground in Oxford between May and August 1992 to analyse the role of learning and social organization m the short‐term responses of hedgehogsErinaceus europaeusto manipulations of food availability On six nights we uniformly distnbuted 36 ‘prey’ (cat food chunks) twice a night in an 70 × 70 m area (the ‘patch’) Prey were placed at sites marked with small flags In a subsequent experiment lasting five nights, non‐marked and randomly distributed prey were provided We regularly mapped the position of individuals, before, during and after both food supplementation treatments Hedgehogs showed a stable pattern of spatial utilisation of the habitat during the non‐hibernation months prior to experimental perturbation Addition of food to parts of the habitat significantly and rapidly changed these patterns a) Hedgehog density increased in food supplemented pans of the habitat b) Hedgehogs learned to associate visual cues with the presence of food c) Hedgehogs learned the spatial location of patches d) Hedgehogs probably engaged in ‘area restricted’ searching Hedgehogs had overlapping home ranges but showed a uniform distribution within patches and avoided conspecifics at distance < 30 m The number of different individuals visiting the area decreased throughout the experiment Food addition did not significantly change the mean density of hedgehogs, perhaps because social interactions placed an upper limit on density in the areas with supplementary food
Changes in size of the Hope Bay Adélie penguin rookery as inferred from Lake Boeckella sediment
Authors: Zale Rolf
Published: July 2006

Concentrations of phosphorus and copper in the sediments of Lake Boeckella (Antarctic peninsula) were used to provide an estimate of the size of the Adélie penguin rookery Pygocetis adeliae Based on dated subsamples from a sediment core, I conclude that penguins have been present in Hope Bay since 5550 BP, with the exception of a short penod around 5300 BP Their influence on the lake sediment reached a maximum at c 40 BP and has drastically declined since then The rookery started to grow between 850 and 1250 BP due to a climate deterioration The increased amount of food (mainly krill), caused by extensive fur seal hunting in the nineteenth century was probably not enough to affect rookery growth However, the drastic decline m whale stock in the 1930's and 1940's and the subsequent increase m krill abundance may have enhanced rookery growth The increasing disturbance by man in Hope Bay seems only to have changed the shape of the rookery and the penguins paths to the sea, but not to have stopped the growth of the rookery
Reproductive timing in Eurasian otters on the coast of Norway
Authors: Heggberget Thrine Moen , Christensen Hanne
Published: July 2006

The seasonal distribution of reproductive phases in female otters and the recruitment of cubs were studied by using information from carcasses collected along the central and northern coast of Norway Relationships between available prey and female body condition were investigated Conception, partuntion and rearing of cubs, at least up to the age of 5–6 months, occurred successfully at all times of the year However, the main birth peak occurred in summer and autumn The frequency of all phases of the breeding cycle, from follicle enlargement to early stages of cub rearing, vaned consistently between seasons Food availability when the cubs were c 2 months old, and energetic demands on the female assumed to be greatest, was probably the main ultimate cause of the seasonal vananon in the recruitment of cubs Intrautenne mortality, possibly due to the seasonal vanation in body condition of females, and loss of litters, may have been important mechanisms in creaung the seasonal recruitment patterns Although the prey biomass on average showed seasonal vanation, the peak season shifted among years and locations It is argued that the availability of suitable prey for otters tend to be unrelated to the seasonal productivity in aquatic environments, due to species–specific growth and behavior of prey and restnctions on the hunting capability of otters Continuous reproduction with seasonal vanation in birth rates may have been maintained by selection for reproductive riskreduction in a nutritionally unpredictable, although generally seasonal, environment
Experimental gingivitis in man
Authors: Theilade Else , Wright W. H. , Jensen S. Börglum , Löe Harald
Published: July 2006

After 9–21 days without oral hygiene eleven experimental subjects with previously excellent oral hygiene and healthy gingivae developed heavy accumulations of plaque and generalized mild gingivitis. The individual rate of development of gingivitis was closely correlated with the rate of plaque accumulation. Characteristic bacteriological changes were revealed in the plaque along the gingival margin during this experiment. Initially, i.e. when the teeth were clean and the gingiva healthy, the extremely sparse plaque flora consisted almost exclusively of gram‐positive cocci and rods. The first phase of plaque development occurred during the first 2 days without oral hygiene and consisted of a proliferation of the gram‐positive cocci and rods and an addition of about 30 per cent gram‐negative cocci and rods. During the second phase (after 1–4 days) fusobacteria and filaments appeared and increased until they each made up about seven per cent of the flora. During the third phase (after 4–9 days) the flora was supplemented with spirilla and spirochetes, and at the end of the period without oral hygiene each of these two groups of organisms accounted for about two per cent of the plaque flora. In specific areas the gingival condition was correlated with the composition of the plaque and it was found that mild gingivitis could be diagnosed clinically at approximately the same time as the complex flora was established. However, sub‐clinical inflammation started much earlier, probably as a reaction to the first phases of plaque development. When oral hygiene was reinstituted, the plaque in most areas disappeared in 1–2 days and after 7–11 days the Plaque Index for each subject was as low as before the experiment. Correspondingly, after 1–2 days most tooth surfaces only harbored the original sparse flora of gram‐positive cocci and rods. The gingival inflammation in an area usually disappeared one day after the plaque had been removed.
Oxidative enzyme activities in keratinizing and non‐keratinizing epithelium of normal and inflamed gingiva
Authors: Löe Harald , Nuki Klaus
Published: July 2006

Biopsies from normal and inflamed human gingiva were frozen and sectioned and then incubated for the demonstration of DPNH and TPNH diaphorases, succinic, lactic, glutamic, isocitric, malic and glucose‐6‐phosphate dehydrogenases. Aerobic enzyme activity was found to be maximal in the basal cell layer decreasing to the surface of both the keratinizing oral and the non‐keratinizing crevicular epithelium. Anaerobic enzyme activity was found to be maximal in the upper prickle cells. No difference in formazan deposition was seen in the oral and crevicular epithelium of normal and inflamed specimens. The enzyme activity of desquamating cells of the crevicular epithelium, however, showed a slightly different pattern. In addition to a general perinuclear formazan deposition in active epithelial cells, areas at the cell periphery corresponding to desmosomes showed an accentuated formazan deposition with all the enzyme systems investigated. The similarity of this distribution of formazan in sections incubated for endogenous reducing activity was tested. The significance of these findings is discussed.
The blood vessels of the dento‐gingival junction
Authors: Egelberg Jan
Published: July 2006

The arrangement of the blood vessels at the dento‐gingival junction was studied in dogs, after perfusion with a carbon‐gelalin mixture. In clinically healthy gingivae a plexus of blood vessels was observed close to the crevicular epithelium. This plexus extended under the entire surface of the crevicular epithelium, from the gingival margin to the base of the crevice. In chronically inflamed gingivae the layered arrangement of the blood vessels seen in healthy gingivae was replaced by a vascular bed with loop‐like formations.
Permeability of the dento‐gingival blood vessels
Authors: Egelberg Jan
Published: July 2006

The vascular labelling method and gingival fluid measurements were applied to studies of the permeability of the dento‐gingival blood vessels. The fluid measurements reflect one aspect of increased permeability; the increased passage of fluid across the vascular walls. The vascular labelling method reflects alterations in the permeability of the vascular endothelium to intravenously injected carbon particles. Increased permeability of the dento‐gingival blood vessels was experimentally produced. It was found that in situations where labelling of the blood vessels occurred, fluid could also be collected from the gingival crevice. With this combination of methods, observation of both the extent and sites of altered permeability could be made.
Dynamics of the inflammatory reaction
Authors: Schultz‐Haudt Stig D. , Sölna Josrein
Published: July 2006

Regardless of the type of tissue injury, the resulting inflammatory reaction usually follows a regular pattern composed of two distinct phases. The first phase, which occurs immediately upon injury, involves a temporarily increased permeability of the small vessels, mainly the venules. of the afflicted area. This rapidly wanes, whereafter the second phase of the reaction ensues. This comprises a prolonged increase of capillary permeability along with a progressive emigration of leucocytes for quit some hours. The further course of the reaction is determined by the type of the injurious agent as well as by the general status of health of the tissues and their previous experience with the injurious agent in question.

It is generally agreed that the inflammatory reaction is induced and mediated by a number of biologically active substances, called mediators, which become activated or released upon tissue injury. It appears that the liberation of histamine is essential for the first phase of inflammation to take place. The course of the second phase is determined by several mediators, since there is accumulating evidence to the effect that increased capillary permeability and emigration of leucocytes are, at least in part, due to different types of mediator substances.

The available evidence suggests that increased proteolytic activity is intimately involved with the progress of the inflammory reaction and is essential for wound healing.
Configuration of periodontal pockets
Authors: Kumar Vinod , Brown Roscoe C. , Stahl S. Sigmund
Published: July 2006

138 males and 231 females between the ages of 20 and 49 years received periodontal examinations in the Periodontia Clinic of New York University College of Dentistry and were grouped according to age and sex. Periodontal pockets depths were recorded around each individual tooth present. The computation analysis of the measurement at 33.204 periodontal pockets was calculated by establishing the significance of “t” and F's values for the variations in periodontal pocket depths. It was noted that the depth of the periodontal pockets at interproximal areas was significantly different from the depth of the periodontal pockets at buccal and/or lingual areas. Comparisons further indicated the direction of significant difference to be toward deeper interproximal pockets at maxillary and mandibular teeth.
Mast cells of the human gingiva
Authors: Zachrisson Björn U.
Published: July 2006

By way of degranulation, the mast cells release a number of biologically active substances into the connective tissue. The present study is concerned with the relation of the gingival mast cells to the pathogenesis of gingivitis. Following fixation in Newcomer's fluid and non‐aqueous staining at pH 0.5 in acridine orange1, topographically defined zones of sections of normal and inflamed marginal gingiva, histologically classified with regard to degree of inflammation, of 56 different individuals have been studied in the fluorescence microscope. The human gingiva was found to be comparatively rich in mast cells. Three main morphological variants were observed and their topographical distribution within the tissue have been described. Marked differences in stainability between mast cells of different areas of the connective tissue have been recorded, and correlated to the state of inflammation, In spite of individual variations in mast cell density, definite patterns of frequency and distribution were observed. The number of mast cells appeared inversely correlated to the density and distribution of the inflammatory cellular exudate within the pocket area of the connective tissue. Consequently, normal gingivae generally contained more mast cells per tissue unit than the moderately inflamed tissue, which, in turn, contained more than the severely inflamed gingivae. Exceptions were found in some moderately inflamed, fibrous gingiva with evidence of strong fibroblastic activity, where there was an increased number of mast cells. On basis of the distribution, frequency and stainability of the mast cells of the gingiva, it is suggested that the mast cells of the regions adjacent to the tooth are subject to an enzymatic degranulation as elicited by products elaborated by the gingival bacterial plaque or possibly by local antigen‐antibody interactions. Substances released by degranulation may then act as mediators during the course of the inflammatory process as well as contribute to the local resistance against injury.
The oxytalan connective tissue fibres in gingival hyperplasia in patients treated with sodium diphenyl‐hydantoin
Authors: Baratieri Antonio
Published: July 2006

Oxytalan fibres in hyperplastic gingival papillae from 12 young epileptics who had been treated with sodium diphenyl‐hydantoin were studied with modifications of Fullmer and Lillie's (1958) and Löe and Nuki's (1964) staining methods. These fibres were compared with the fibres in clinically normal gin‐givac and in tissue from fibrous epulides.

Fibres reacting with peracetic acid‐aldehyde fuchsin (i.e. oxytalan fibres) were present throughout the connective tissue and were especially numerous near the surface epithelium and in areas of inflammatory infiltration. The oxytalan fibres were especially prominent along the junction with epithelium, between the rete pegs and in the deeper connective tissue near bone where they tended to be arranged in large parallel bundles. In cases of fibrous epulis, however, there were very few oxytalan fibres in the connective tissue adjacent to the surface epithelium.

It is concluded that the connective tissue performs an important supportive function to the epithelium in gingival hyperplasia, and is of special importance in the genesis of gingival hyperplasia in patients under treatment with sodium diphenyl‐hydantoin.
The effect of hypervitaminosis D on the periodontal membrane collagen in lathyritic rats
Authors: Shoshan Shmuel , Pisanti Sarah , Sciaky Ino
Published: July 2006

Toxic doses of vitamin D2 (5 × 100000 U) were administered to lathyritic rats which received aminoacetonitrile in drinking water for 15 days. The peridontal membrane (PDM) of the molars was examined both histologically and biochemically. The PDM collagen of the lathyritic animals could be extracted with cold 0.15 M NaCI, whereas that of the normal controls, or of the animals which received either the vitamin alone or both the lathyrogen and the vitamin was not extractable. Ossification of the PDM and supraalveolar connective tissue was apparent in the lathyritic group which received toxic doses of the vitamin but not in either lathyrism or hypervitaminosis alone. It is concluded that whereas the release of calcium from bone or the increased absorption of the mineral from the intestine is affected by vitamin D, its deposition in the soft connective tissues may depend on the nature of the protein matrix.
Formation of dentin and bone matrix in magnesium‐deficient rats
Authors: Trowbridge Henry O. , Seltzer Judith L.
Published: July 2006

Collagen formation and the sulfation of protein‐polysaccharides in the organic matrix of bone and dentin was studied in young, magnesium‐deficient rats of the Long‐Evans strain. Autoradiography was employed to assess the incorporation of tritiated proline into collagen, and 35S sulfate was utilized to study the sulfation of protein‐polysaccharides. Our observations on the uptake of these radioactive precursors indicate that a deficiency of magnesium interferes both with collagen formation and the sulfation of glycosaminoglycuronoglycans in the organic matrices of bone and dentin. Alkaline phosphatase activity, determined in serum samples and observed histochemically in calcifying tissues, was depressed in the magnesium‐deficient animals as compared with controls. The localization of alkaline phosphatase activity in bone and dentin forming tissues from experimental rats was found to be similar to that of the controls, but the intensity of the staining reaction was reduced in the tissues from the magnesium‐deficient animals. Suppression of enzyme systems known to be activated by magnesium and related to protein and protein‐polysaccharide biosynthesis would, in part, explain the results of this experiment.
Influence of horinonal contraceptives on the gingiva of women
Authors: Lindhe Jan , Bjorn Anna‐Lisa
Published: July 2006

Gestagen hormones commonly used as contraceptive in women, induce a hormonal situation which to some extent simulates pregnancy. The aim of the present investigation was to study the gingival conditions of women before and during 12 months of regular ose of contraceptive preparations. Two kinds of contraceptives were used: Delpregnin® and Gestadydral®. The mesial aspects of the gingiva of 5 maxillary incisors and canines were studied before beginning the experiment and after 2, 6, and 12 montks of hormone therapy. Jntracrevicolar sampling of gingival exudate was performed a.m. Brill (1959).

Both the Delpregnin‐group and the Gestadydral‐groiip showed an increase in amount of exudate during the 12 months. At the use of Delpregnin there was a gradual increase in exudation during tke first six months of hormone therapy. In the group using Gestadydral, no increase in amount of exudate could be noted during the first six months, whereas a significant increase of the gingival exudate occurred between the last two examinations.

The findings are discussed in view of current knowledge of gestagene hormone action on vascular permeability.
Flow of gingival exudate as related to menstruation and pregnancy
Authors: Holm‐Peedersen P. , Löe Harald
Published: July 2006

The gingival condition of i4 young women was studied through 3‐4 consecutive menstrual cycles. The gingivae were scored according to Gingival Index system and gingival exudate was assessed at regular intervals during the experimental period. The results showed that the menstrual cycle was without effects on the state of the clinically normal gingiva. However, pre‐existing gingivitis seemed to aggravate during menstruation. The mean flow of exudate from normal gingiva corresponded to that of a control group consisting of 16 young men, indicating that the menstrual cycle did not affect the flow of gingival fluid from normal gingiva. An additional series of exudate measurements on 42 women during pregnancy and post partum showed that gestation did not influence the flow of fluid from normal gingiva.
Biologically active substances of the mast cell
Authors: Zachrisson Bjørn U. , Schulz‐Haudt Stig D.
Published: July 2006

The mast cells have been shown to contain a number of biologically active substances, some of which may contribute to the various phases of the inflammatory reaction. The present article deals with an evaluation of the potential role of the products of the mast cell metabolism in inflammation in general and in gingivitis in particular. In order for the various substances contained within the mast cells to act, they must be liberated into the connective tissue by degranulation of the cells. Among the released substances, histamine, proteolytic‐esterolytic enzymes, “slow reacting substance”, lysolecithins and heparin have been related to the development and course of inflammation in humans. Other factors, including, serotonin, unsaturated fatty acids and β‐glucaronidase, seem to be of minor importance. The functions of the mast cell ascorbic acid, and phosphatases are not known.
Occurrence of Bacterianema matruchotii and Bacteroides melaninogenicus in gingival plaque from monkeys
Authors: Cock D.J. , Bowen W.H.
Published: July 2006

Differences could not be detected between the populations of total aerobes, total anaerobes, Bacteroides melaninogenicas, or Bmcterionerna matruchotii in plaque from periodontally diseased (PD) monkeys and that taken from normal animals (N). Although all animals were fed the same high carbohydrate diet for more than two years, the PD monkeys had a much greater abundance of plaque than the N monkeys. It is suggested that this difference is due to fibrin and blood coagulum providing a aides for the deposition of plaque and blood or serum from the ulcerated col, and later from the ulcerated crevicular epithelium, promoting the growth of microorganisms at the gingival margin.
Histometric study of age changes in interradicular bone of Wistar rats
Authors: Otero Rodolfo López , Carranza Fermin A. , Cabrini Rómulo L.
Published: July 2006

Age changes in the interradicular bone of rat first molars were studied in mesio‐distal sections by means of a histometric technique based on an integration method with a points system. The lower jaw showed a gradual increase in density while the upper jaw showed an initial increase, a plateau and a reduction in density with age.
Electron microscopic features of the newly formed epithelial attachment after gingival surgery
Authors: Lstgarten Max A.
Published: July 2006

Deciduous first molars with the buccal gingiva in situ were obtained from three year old cynomologus monkeys 2 months and 4 months after gingivectomy. Of the four specimens examined to date, all showed formation of a new epithelial attachment consisting of hemidesmosomes and a basement lamina. In some areas this attachment apparatus connected the cells directly to the tooth surface. In other areas, “cuticular” structures were interposed between the attachment apparatus and the tooth surface. Although the layers intervening between the attachment apparatus and the tooth surface may represent acquired pellicles, they may also be due to denaturation of superficial layers of cementum. Any factor affecting the integrity of the epithelial tissue, the attachment apparatus or these “cuticles” could result in breakdown of the epithelial attachment.
Periodontal microcirculation as revealed by plastic microspheres
Authors: Folke L.E.A. , Stallard R.E.
Published: July 2006

Plastic microspheres 15 ± 5 microns were injected into the right external carotid artery of five Squirrel monkeys. One animal was sacrificed at 1, 24 and 36 hours and two animals at one week. The jaws were removed, fixed, demineraized and sectioned bucco‐lingually. The vascular patterns in the connective tissue beneath the oral epithelium, epithelial attachment, “col” area and within the periodontal membrane were examined. The vascular tree supplying the oral epithelium was visualized as running perpendicular to the outer surface while that in the attachment area paralleled its epithelial surface. The “col” area, on the other hand, demonstrated a combination of both vascular patterns. The diameter of the terminal arterioles just beneath the epithelial basement membrane ranged from 13.6 to 20.4 microns and varied little in the three areas examined. The vessels within the periodontal ligament were connected into a net‐like plexus receiving its primary bloodsupply from vessels penetrating the lamina dura perpendicularly.
The effect of supervised oral hygiene on the gingiva of children. The effect of sodium fluoride
Authors: Koch Göran , Lindhe Jan
Published: July 2006

The effect of sodium fluoride on the gingiva of children was investigated by regularly applying sodium fluoride to the teeth and gingiva for three years in two different ways:

1. In a dentifrice slurry during daily supervised toothbrushing. The concentration of sodium fluoride was approximately 0.05 %.

II. As a mouth rinse with 10 ml of an 0.5 % aqueous solution of sodium fluoride once every second week.

The study included two control groups. The first, supervised by a dental nurse, brushed their teeth daily, using a dentifrice free from the fluoride component. The second rinsed their mouths once every second week with distilled water.

The total number of children was 471 : 236 in the experimental groups and 235 in the control groups. At the time of the clinical examination, all were 12 14 years of age.

The gingival state and the oral hygiene were recorded with the indices proposed by Löe and Silness (1963). and Silness and Löe (1964).

The investigation revealed that:

Sodium fluoride applied by means of a dentifrice slurry did not affect the gingiva.

Sodium fluoride in the concentration of 0.5 % in a mouth rinse proved detrimental to the gingiva.

The GI of the “fluoride rinsing group” was 0.75, whereas that of the “distilled water rinsing group” was 0.61.

These results are discussed in the light of current knowledge of the effect of fluorine in dental plaques and connective tissues.
Spontaneous periodontal disease in the mongolian gerbil
Authors: Moskow Bernard S. , Wasserman Bernard H. , Rennert Morton C.
Published: July 2006

The pathogenesis of periodontal lesions in the Mongolian gerbil (meriones ungiculatus) was studied in sixty‐one animals varying in age from two months to five years. Both gross morphologic and histological techniques were employed. The results of this investigation indicate a slowly progressing, insidious form of inflammatory periodontal breakdown in this animal apparently related to the accumulation of plaque and calculus‐like accretions. Because of the many morphologic similarities of the periodontal lesion in the gerbil to those of the human periodontal problem, it is felt that this animal is ideally suited for periodontal research.
Cell contacts in oral epithelia
Authors: Thilander Holger , Bloom Gunnar D.
Published: July 2006

Biopsies from normal, non‐inflamed buccal gingiva, palatal gingiva, retromolar and upper vestibular mucosa were obtained from 12 adult patients for an electron microscopical investigation of cell contacts in the epithelial layers. The junctional complexes found were desmosomes, tight junctions and intermediate junctions. In parakeratotic or poorly keratinized epithelium (e.g. retromolar and vestibular mucosa, gingiva) the desmosomes maintained their typical appearance in all layers. In highly keratinized epithelium (e.g. palatal gingiva) the structure of the desmosomes changed in the stratum corneum to a three‐layered structure between the thickened cell membranes. The tight junctions were classified as maculac occludentes in the basal layer and the stratum spinosum and as zonulae occludentes in the stratum granulosum and the stratum corneum. The intermediate junctions were rather numerous and of different length. The principal mode of attachment of clear cells to adjoining epithelial cells seemed to be of this type. At the tissue surface the orifices of the intercellular spaces were closed by tight junctions or modified desmosomes. No such junctional complexes were found at the orifices of the intercellular spaces to the basement membrane. In the light of the findings some permeability conditions of oral epithelia are discussed.
Hertwigs sheath in the rat incisor
Authors: Shibata F. , Stern I. B.
Published: July 2006

The histodynamic nature of Hertwig's sheath of the mandibular rat incisor was studied utilizing tritiated thymidine. The epithelial sheath is composed of three distinct cell layers: (1) inner dental epithelium, (2) stellate reticulum, and (3) outer dental epithelium. Incisal to the basal loop area, the outer layers eventually diminish and disappear leaving only the inner dental epithelium. This layer ultimately becomes perforated and is replaced by connective tissue elements. Epithelial rest cells are not identifiable in the periodontal ligament. Autoradiographic study shows labeling to be more frequent in the inner dental epithelium than the other two epithelial layers. At the one hour period, 97 per cent of the labeled cells in the inner dental epithelium are located in the basal two‐thirds of the area between the basal loop and the site of predentin deposition. A study of cell kinetics indicates that the inner dental epithelium is made up of a renewing cell population. The cells have a total generation time of 25.3 hours; a synthesis period of nine hours; a G2 period of two to six hours; a mitotic period of approximately one‐half hour, and a G1 period ranging from 9.8 to 13.8 hours. The rate of cell migration is of the same order as the rate of tooth eruption (358 μ per day).
A reproducible method of evaluating oral hygiene
Authors: Pilot T.
Published: July 2006

A reproducible method of evaluating oral hygiene has been developed for use in blind studies. An erythrosin‐containing disclosing solution is applied and black and white photographs taken of the 12 anterior teeth.

The method was evaluated by one investigator on a group of 35 experimental subjects. The reproducibility of the results were estimated by scoring from the same photographs after intervals of one month and ten months. In addition, reproducibility was tested by re‐photographing the anterior teeth of the same subjects with variations in the position of the camera. Variations of up to 15 degrees in the vertical and horizontal planes were tested.

It was found that errors with this method were small and that it is sufficiently accurate for controlled studies. Also it has shown that focusing with a hand‐held camera, without special equipment to fix the patient/camera relationship, is satisfactory.
Endogenous oxygen consumption rates of bovine attached gingiva
Authors: Lainson Phillip A. , Fisher Alton K.
Published: July 2006

This investigation provided oxygen quotients of slices of bovine whole attached gingiva, the epithelium and the connective tissue. Respiratory measurements were made on an hourly basis for three consecutive hours with Gilmont differential syringe manometers according to the direct Method of Warburg at 37.5 C. Oxygen quotients were calculated on a microliter per milligram of dry tissue per hour basis. Although a very slight but progressive decline in respiratory rate during the 3 hours of observation was noted in the three classes of tissue samples, the values of the oxygen quotients for each hour within each class were remarkably similar. The mean oxygen quotients obtained for slices of whole attached gingiva, epithelium, and connective tissue are 1.56, 2.09 and 0.69, respectively. The oxygen quotient for bovine gingiva is similar to that reported by others for human gingiva but lower than that reported for rat gingiva. The oxygen quotient for the connective tissue is similar to that of bovine slightly dentinogenically active dental pulp. Oxygen quotients calculated on a different basis in another laboratory yielded higher values for human gingival epithelium and connective tissue than are reported here but there is agreement that respiratory activity of the epithelium is about three times as great as that of the connective tissue. The abundance of stroma in the latter could account for the difference, but the oxygen quotients for the two specific types of cells remain to be determined.
Nonbanded fibrils of collagenous nature in human periodontal connective tissue
Authors: Selvig Knut A.
Published: July 2006

Human teeth with adhering periodontal tissues were obtained and processed for electron microscopy. Thin sections were cut through cementum and adjacent soft tissue. An increased occurrence of nonbanded fibrils was observed near the root surface adjacent to marginal areas of chronic inflammation. Bundles of fine filaments protruded from the cementum surface as extensions of cross‐banded matrix fibrils. Nonbanded filaments were seen between collagen fibrils in the periodontal ligament as well as in direct continuation of such fibrils. In areas were beading of the filaments could be distinctly observed, the periodicity of the beading often corresponded to the periodicity of collagen cross banding. The number of filaments present in various sites appeared to be inversely proportional to the amount of intact collagen fibrils remaining. The location and appearance of the nonbanded structures indicate that they to a large extent represent partially decomposed collagen fibrils.
S35‐sulfate utilization and turnover by the connective tissues of the periodontium
Authors: Baumhammers A. , Stallard R. E.
Published: July 2006

The utilization and turnover of injected S35‐sulfate by the connective tissue of the periodontium was studied in 28 IRC strain mice, 14 one month old and 14 one year old. The isotope was administered by intraperiotoneal injection in a dosage of 20 uc of sodium S35‐sulfate per gram of body weight. The animals were sacrificed 1, 4 and 12 hours, 1 and 4 days and 1 and 2 months after the injection. Following fixation and decalcification, the tissues of the head were processed by histrologic, radioautographic and enzymatic digestion techniques:Analysis of the results permitted the drawing of the following conclusions:1) the injected S35‐sulfate did label certain of the sulfated mucopolysaccharides of the amrophous ground substance of the periodontal ligament, cementum, alveolar bone and dentin; 2) the fibroblasts, cementblasts, osteoblasts and odnotoblasts apparently take part in the synthesis of the sulfated mucopolysaccharides; 3) the labeled sulfated mucopolysaccharides in the periodontal ligament turned over rapidly and the rate did not appear to decrease with age; 4) within the mineralized matrix of the alveolar bone, detin or cementum no turnover of the sulfated mucopolysaccharides was detected;and 5) cementoblastic, osteoblastic and odontoblastic synthetic activity in regards to the utilization of S35 sulfate decreased with age except in the case of the continually erupting incisior.
The effect of age on the proliferative activity of certain epithelial tissues
Authors: Lavelle C. L. B.
Published: July 2006

The cellular dynamics of certain epithelial tissues from the oral cavity were compared with those from the ear, in rats aged between ten and seven hundred and fifty one days, using autoradiography. The results indicated that the proliferative activity of these tissues decreased in the initial stages of life, thereafter to remain virtually constant; the tissues from the oral cavity proliferating considerably faster than those from the ear.
Human gingival mast cells
Authors: Shelton L. E. , Hall W. B.
Published: July 2006

The literature concerning changes in mast cell populations in human gingiva associated with inflammation is contradictory. No reports of the effects of therapy on these populations have been published.This study was designed to determine whether gingival mast cell populations are altered by inflammation and whether these populations change following routine therapy. Twenty systemically healthy patients, age 20 to 40, ten with normal gingiva and ten with periodontitis of similar severity bilaterally, were selected for study. Biopsies of interdental papillae from premolar regions were utilized. In the periodontitis group, one papilla was obtained prior to therapy, the second from the ipsilateral quadrant two weeks after root planing and curettage.

Mast cell populations were determined from frozen sections stained with EACNAS‐GBC Hematoxylin (Hall, 1966). Granule estimates were obtained from photographic negatives of frozen sections stained with EACNAS‐GBC alone, using a photoelectric assaying device. Mast cell counts and granule estimates were made separately for beneath col and beneath keratinized tissue. Results show a larger mast cell population and a greater granule estimate under keratinized tissue than beneath the col. Mast cell counts and granule estimates show a decrease during periodontitis and a return to “normal” limits following routine therapy. These results support the concept that mast cell numbers are decreased in the presence of chronic inflammation but return to “normal” levels following resolution of the inflammatory process.
Salivary enzymes and calculus formation
Authors: Draus F.J. , Tarbet W.J. , Miklos F.L.
Published: July 2006

The purpose of this study was to determine if enzymatic activities could be correlated with calculus formation. Subjects were grouped as to their ability or inability to form calculus after a three month “accumulation” period. Saliva samples from each subject were collected and the enzymatic activities of nonspecific esterase, acid phosphatase, pyrophosphatase, neuraminidase, protease, and lactic dehydrogenase were determined by routine analysis. Statistical evaluation of the data using the standard t test indicated that esterase activity has a high correlation to calculus formation, p < .005; pyrophosphatase activity also correlated with calculus formation, p < .02. Acid phosphatase activity correlated to a lesser degree, p < .05. No other significant correlations were found. A possible sequence for salivary calcification is presented.
The epidemiology of chronic periodontal disease in Western Nigerian schoolchildren
Authors: Sheiham Aubrey
Published: July 2006

An epidemiological study of periodontal disease in Ibadan, Ilora, Akufo and Ijebu Ode schoolchildren aged 10 years and older was conducted in 1964. The study involved 1161 Ibadan, 227 Ilora, 85 Akufo and 147 Ijebu Ode schoolchildren. Periodontal disease was assessed using the Periodontal Index and oral cleanliness was assessed using the Oral Hygiene Index. Periodontal disease was highly prevalent, over 99 per cent of the children examined were affected. The periodontal disease was severe, the majority of the children had severe gingivitis or early destructive periodontal disease. There was a regional variation in the severity of periodontal disease. Periodontal pocketing was present in 11 per cent of Ilora, 15 per cent of Akufo, 40 per cent of Ibadan and 72 per cent of Ijebu Ode children aged 10 to 14 years. The P. I. for the Ibadan primary schoolchildren aged 15 to 19 years was higher than the P. I.for Ibadan secondary and grammar schoolchildren of a similar age. In Ibadan grammar schoolchildren the mean P. I. for 15 to 19 year olds was lower than the P. I. for 10 to 14 year olds whereas the P. I.for primary and secondary schoolchildren did not show this decrease with increasing age. The O.H.I. was higher in children aged 10 to 14 than 15 to 19 years and males had poorer oral cleanliness than females. It was concluded that the grammar schoolchildren had less severe periodontal disease and better oral cleanliness than primary and secondary schoolchildren and that there was a regional variation in the severity of periodontal disease which may be associated with variations in diet.
Influence of sex hormones on gingival exudation in gingivitis‐free female dogs
Authors: Lindhe Jan , Attström Rolf , Björn Anna‐Lisa
Published: July 2006

This investigation was undertaken to study the influence of an increased level of estrogen and progesterone upon gingival exudation in gingivitis‐free female dogs. Four female dogs constituted the experimental material. For three weeks prior to the hormone study all were supplied with a hard diet consisting of raw bovine tracheas. In addition, the teeth were cleaned every second day with rubber cups and pumice. During the experimental period gingival fluid was collected from the buccal areas.

The intra‐crevicular method was applied in three quadrants and the extra‐crevicular in one quadrant. A total of seven strips from six teeth were measured in each quadrant. Gingival fluid was sampled five times during the course of this study; once immediately before and once seven days after each of the two hormone periods and twice during the course of hormone administration. During the first hormone period comprising 52 hours, each dog was twice given 1 mg estrogen and 25 mg progesterone. During the second hormone period, which also lasted for 52 hours, the dose of each hormone was doubled. The hormones were injected intramuscularly in the hind leg. The results show that when the intra‐crevicular technique of sampling was used, the administration of estrogen and progesterone induced an increased flow of gingival fluid. The increased gingival exudation was observed in all four dogs and occurred in both of the hormone periods. At the end of the period of sex hormone administration the gingival exudation returned to normal. The present study also showed that no influence of sex hormones on gingival exudation could be demonstrated by the extra‐crevicular sampling method.