Showing papers by "University of Gothenburg published in 1982"

New attachment following surgical treatment of human periodontal disease.

Abstract: The present experiment was undertaken to test the hypothesis that new connective tissue attachment may form on a previously periodontitis involved root surface provided cells originating from the periodontal ligament are enabled to repopulate the root surface during healing. A mandibular incisor with advanced periodontal disease of long standing (the distance between the cemento-enamel junction and the alveolar bone crest was 9 mm) was subjected to periodontal surgery using a technique which during healing prevented the dentogingival epithelium and the gingival connective tissue from reaching contact with the curetted root surface. Preference was hereby given to the periodontal ligament cells to repopulate the previously diseased root surface. After 3 months of healing a block biopsy containing the incisor and surrounding tissue was sampled. The histological analysis revealed that new cementum with inserting principal fibers had formed on the previously diseased root surface. This new attachment extended in coronal direction to a level 5 mm coronal to the alveolar bone crest. This finding suggests that new attachment can be achieved by cells originating from the periodontal ligament and demonstrates that the concept that the periodontitis affected root surface is a major preventive factor for new attachment is invalid.

Female choice selects for extreme tail length in a widowbird

Abstract: Darwin's1 hypothesis that male secondary sexual ornaments evolve through female preferences is theoretically plausible2–7, but there is little experimental field evidence that such preferences exist8–10. I have studied female choice in relation to male tail length in the long-tailed widowbird, Euplectes progne, and report here that males in which the tail was experimentally elongated showed higher mating success than males having normal or reduced tails. The possibility that intrasexual competition among males maintains the long tail was not supported: males with shortened tails held their territories as long as did other males. These results suggest that the extreme tail length in male long-tailed widowbirds is maintained by female mating preferences.

Sexual selection, natural selection and quality advertisement

Abstract: In Darwin's and Fisher's theory of sexual selection, females prefer ornamented males; the evolution of larger ornaments is limited by increased mortality, lor example through predation. An adornment of given size should often raise mortality more in low than in high quality phenotypes. Possible consequences for the evolution and optimal size of ornaments are here examined with mathematical models. Fisher suggested that an ormamem may evolve if it initially improves male survival. Female preference then spreads for adorned males. Their consequent mating advantage furthers propagation of the preferred trail. An alternative, the ‘handicap mechanism’, suggests that only those males best able to survive can do so with a large, handicapping ornament. Choosing adorned males, females might therefore bear offspring with high general survivorship, but sons also inherit the handicapping ornament. When it reduces survival more in low than in high quality phenotypes, the handicap mechanism (in conjunction with the Fisherian mating advantage) becomes powerful with lower heritability of fitness than previously supposed. It still requires that fitness has some heritability, for which there is indirect evidence, but field measurements are lacking. In Darwin's and Fisher's theory, both mating advantage and mortality disadvantage increase with ornament size, and balance at its optimal development. If a given adornment reduces survival most in low quality phenotypes, the optimum increases with phenotypic quality. Ornament size then may provide a measure of fitness, and can be used in mate choice. A male can usually not gain fitness by developing larger adornments than other males of the same quality. Ornaments can probably also evoke through direct competition between males, without female preferences for adorned males. Field experiments are needed to clarify this and other aspects of sexual selection. Sexual ornaments form part of the reproductive effort. Certain predictions from life-history theory should therefore apply. One is that ornaments will increase in size over the first few reproductive seasons; this is the case in many species.

Bacterial leakage around dental restorations: its effect on the dental pulp

Abstract: This study revealed that the quantity of bacteria filtered from the base of Class V cavity restorations were directly related to the type of medicament used. Of the brands studied: composite, amalgam, silicate, and guttapercha – each produced varying numbers of bacterial colonies, whereas zinc oxide and eugenol cement showed none. Histopathology of the pulps correlated directly to the microbiological data.

On the relation between sea‐surface heat flow and thermal circulation in the ocean

Abstract: A theoretical framework for the description of the thermal state and circulation in the ocean is presented. Relations between differential heating, diffusive heat flux and surface drift are derived and discussed in the light of the basic mechanical property of the system, i.e. the tendency for light water to spread on top of heavier water. We find that for low and medium temperatures, the poleward surface drift can be determined directly from a knowledge of the heat flux through the sea surface. Preliminary quantitative estimates indicate that the “Hadley circulation” for the entire ocean involves a volume flux of order 70 ± 30 Sverdrup. For the North Atlantic we find a poleward drift of order 10 Sverdrup which compares well with previous estimates of the southward deep flow. Mean values for the diffusive flux in the ocean are found to be of order 20 W m -2 at 15 °C and 60 W m -2 at 25 °C. DOI: 10.1111/j.2153-3490.1982.tb01806.x

Influence of combinations of oral bacteria on periapical tissues of monkeys.

Abstract: The present study deals with the ability of 11 bacterial strains, in various combinations, to induce periapical reactions. The indigenous oral bacteria were originally isolated from an experimental apical periodontitis in monkey. Eight of the strains were complete collection isolated from one root canal. These strains were inoculated together, in equal proportions, into 12 root canals. In addition, 63 canals were inoculated with other combination or separate strains. At the end of the experimental period it was found that in the mixed infections the Bacteroides oralis strain predominated in most root canals. In contrast, this Bacteroides strain was not reisolated in any of nine root canals when inoculated in a pure culture. Enterococci, however, survived as pure cultures in all canals. The mixed infections showed the greatest capacity of inducing apical periodontitis, as revealed by radiography, and most pronounced was the "eight-strain collection". The facultatively anaerobic streptococci induced only weak periapical reactions.

Predominant indigenous oral bacteria isolated from infected root canals after varied times of closure.

Abstract: The pulps of 24 root canals, eight in each of the three monkeys, were mechanically devitalized and exposed to the mouth flora for about 1 week and thereafter sealed. Microbiologic sampling and analysis was performed in 16 teeth (two of the monkeys) after 7 d of closure (initial samples). The teeth of the three monkeys represented observation times of 90, 180 and 1060 d. At the end of each observation period final samples were taken. Final sampling included samples from the main root canal, the dentin, and the apical region at the same sampling session. All microbiologic analyses were carried out quantitatively. Final root canal samples from the apical region showed a predominance of obligately anaerobic non-sporulating bacteria, in fact 85-98% of the bacterial cells were anaerobic. The most frequently found species were Bacteroides and Gram-positive anaerobic rods. A lower proportion of facultatively anaerobic bacteria was found. This was most pronounced for coliform rods in comparison with strains of B. melaninogenicus.

Induction of a DNA glycosylase for N-methylated purines is part of the adaptive response to alkylating agents.

Abstract: The resistance of Escherichia coli to simple alkylating agents, for example N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), is markedly increased in cells previously exposed to low doses of the agents. This adaptive response seems to reflect improved repair of alkylation lesions in DNA, and cells become less sensitive to both the mutagenic and killing effects of alkylating agents1,2. Adaptation to the former is due largely to the induction of a repair function that removes O6-methylguanine (m6G) from DNA3,4. This activity has been purified from induced cells and is attributed to a protein that transfers the methyl group of an m6G residue in DNA to one of its own cysteine residues5. Consequently, no excision of damaged nucleotide residues seems to be necessary. The adaptive response to killing by alkylating agents, however, is less understood. DNA excision–repair with gap-filling catalysed by DNA polymerase I seems to occur as part of the inducible response, as it depends on the presence of a functional polA+ gene2 and enhanced DNA polymerase I-mediated repair synthesis has been observed in adapted cells challenged with MNNG6. Here we show that the adaptive response involves induction of not only a methyltransferase for m6G, but also a DNA glycosylase that catalyses the release of purines methylated at ring nitrogen atoms. We also identify the minor alkylation product 3-methyl-guanine (m3G) as an important lethal lesion.

“Critical probing depths” in periodontal therapy

Abstract: The present investigation was carried out on 15 individuals who were referred for treatment of moderately advanced periodontal disease. All patients were first subjected to a Baseline examination comprising assessment of oral hygiene and gingival conditions, probing depths and attachment levels. Following case presentation and instructions in oral hygiene measures, the patients were given periodontal treatment utilizing a split mouth design. In one side of the jaw scaling and root planing were performed in conjunction with a modified Widman flap procedure while in the contralateral jaw quadrants the treatment was restricted to scaling and root planing only. The period from initial treatment to 6 months after treatment was considered to be the healing phase and from 6-24 months after treatment the maintenance phase. During the healing phase the patients were recalled for professional tooth cleaning once every 2 weeks. During the maintenance phase the interval between the recall appointments was extended to 3 months. Reexaminations were carried out 6, 12 and 24 months after the completion of active treatment. The results revealed that treatment resulted in loss of clinical attachment in sites with initially shallow pockets, while sites with initially deep pockets gained clinical attachment. With the use of regression analysis "critical probing depths" were calculated for the two methods of treatment used. It was found that the critical probing depth value for scaling and root planing was significantly smaller than the corresponding value for scaling and root planing used in combination with modified Widman flap surgery (2.9 vs 4.2 mm). In addition, the surgical modality of therapy resulted in more attachment loss than the non-surgical approach when used in sites with initially shallow pockets. On the other hand, in sites with initial probing depths above the critical probing depth value more gain of clinical attachment occurred following Widman flap surgery than following scaling and root planing. The data obtained from the reexaminations 12 and 24 months after active treatment demonstrated that the probing depths and the attachment levels obtained following active therapy and healing were maintained more or less unchanged during a maintenance care period which involved careful prophylaxis once every 3 months. However, the data also disclosed that the level of oral hygiene maintained by the patients during healing and maintenance was more critical for the resulting probing depths and attachment levels than the mode of initial therapy used.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibition of experimental ascending urinary tract infection by an epithelial cell-surface receptor analogue

Abstract: It has been shown that the establishment of urinary tract infection by Escherichia coli is dependent on attachment of the bacteria to epithelial cells. The attachment involves specific epithelial cell receptors, which have been characterized as glycolipids. Reversible binding to cell-surface mannosides may also be important. This suggests an approach to the treatment of infections--that of blocking bacterial attachment with cell membrane receptor analogues. Using E. coli mutants lacking one or other of the two binding specificities (glycolipid and mannose), we show here that glycolipid analogues can block in vitro adhesion and in vivo urinary tract infection.

Association between Plasma Level of Growth Hormone and Sex Differentiation of Hepatic Steroid Metabolism in the Rat

Abstract: The hypothesis that the plasma pattern of growth hormone (GH) regulates hepatic steroid metabolism in the rat was studied in two different animal models: 1) different plasma patterns of GH were achieved by the administration of human GH at different frequencies or by infusing the hormone continuously by means of Alzet osmotic minipumps to hypophysectomized female rats and 2) the plasma pattern of GH in animals with an intact pituitary gland was investigated under conditions which lead to feminization of hepatic steroid metabolism. The pattern of GH was determined by studying minimum and maximum plasma GH levels in blood samples taken from the tip of the tail at various times. After continuous administration of human GH to hypophysectomized female rats, the liver microsomal metabolism of 4-[4-14C]androstene-3,17-dione was feminized, e.g. the ratio between 5α-reductase and 16α-hydroxylase activities (5α/16α ratio) increased from 2.45 ± 0.21 to 31.2 ± 1.76. Similar results were observed when the animals were...

Exposure to Anaesthetic Gases and Spontaneous Abortion: Response Bias in a Postal Questionnaire Study

Abstract: A postal questionnaire study on anaesthetic gas exposure and miscarriage rate was performed among women who worked or had previously worked in a Swedish hospital. Results were evaluated in relation to age, smoking habits, work site at the first trimester of pregnancy and clinical accuracy of the reported data. An important part of the study was the collection of information on pregnancies among non-respondents. A higher, although non-significant, miscarriage rate was reported among women who had worked in areas with high exposure during the first trimester compared to unexposed women. A selection was found among the non-respondents with respect to both working site during pregnancy and outcome of pregnancy. All women suffering a miscarriage while working at sites with exposure to anaesthetic gases reported their work site and miscarriage, while one third of all miscarriages occurring to women who were not exposed during pregnancy were not reported in the questionnaire.

5-hydroxytryptamine and cholera secretion. Physiological and pharmacological studies in cats and rats.

Abstract: The intestinal secretion evoked by close intra-arterial infusion of 5-hydroxytryptamine (5-HT) in cats was inhibited by tetrodotoxin, a drug abolishing action potentials. Furthermore, the intestinal secretion produced by placing a 2-mM 5-HT solution in the intestinal lumen of rats was inhibited by hexamethonium, a ganglionic receptor-blocking agent. These observations strongly indicate that 5-HT-induced secretion is, at least in part, neurally mediated. It was also shown that 5-HT receptors are involved in the pathophysiology of choleraic secretion, since the secretion was inhibited by making the experimental animal tachyphylactic against 5-HT. No effects of 5-HT tachyphylaxis were noted on fluid transport in normal intestines. The results are discussed in relation to a new hypothesis for the pathophysiology of cholera secretion.

Effect of longstanding jiggling on experimental marginal periodontitis in the beagle dog.

Abstract: The aim of the present experiment was to study the effect of a prolonged period of jiggling force application on the rate of progression of ligature-induced, plaque-associated marginal periodontitis in the beagle dog. The experiment was performed on eight dogs fed a diet which permitted dental plaque accumulation. On Day 0 a phase of periodontal tissue breakdown was initiated around the mandibular fourth premolars (4P; P4) by the placing of plaque retention ligatures around the neck of the teeth. The ligatures were exchanged once a month throughout the entire study. On Day 60 trauma from occlusion of the jiggling type was produced in the P4 region and maintained for 300 days. The animals were sacrificed on Day 360. Following sacrifice tissue sections comprising 1M, 4P, 3P and P3, P4, M1 were produced and subjected to microscopic analysis. The experiment revealed that in the dog jiggling forces applied to teeth which ae also subjected to ligature-induced and plaque-associated marginal periodontitis, may enhance the rate of destruction of the periodontium.

Sex pheromone components of the turnip moth,Agrotis segetum : Chemical identification, electrophysiological evaluation and behavioral activity.

Abstract: Analysis of female abdominal tips ofAgrotis segetum by means of GC-MS showed the presence of 13 aliphatic acetates and alcohols. (Z)-7-Dodecenyl acetate was found to be the main component in the extracts at amounts of about 1 ng/female. (Z)-9-Tetradecenyl acetate and (Z)-7-dodecenol were present to the extent of 49 and 19%, respectively, of the main component. Minor components could be identified as decyl acetate, (Z)-5-decenyl acetate, dodecyl acetate, (Z)-9-dodecenyl acetate, tetradecyl acetate, a tetradecenyl acetate, hexadecyl acetate, a hexadecenyl acetate, (Z)-5-decenol, and (Z)-9-tetradecenol. The presence and biological activity of decyl acetate, (Z)-5-decenyl acetate, and (Z)-7-dodecenyl acetate in the extracts could be detected by GC-EAD. Tested by EAG (Z)-5-decenyl acetate evoked the highest response among pheromone candidates, followed by (E)-5-decenyl acetate and (Z)-7-dodecenyl acetate. Single-cell recordings from 100 male antennal sensilla trichodea revealed receptorcells highly sensitive to (Z)-5-decenyl, (Z)-7-dodecenyl, (Z)-8-dodecenyl, and (Z)-9-tetradecenyl acetate as well as (Z)-5-decenol. The (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetate receptors were activated significantly also by female extracts. When tested in a tube olfactometer, a blend of decyl, (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetate evoked the same male response as did female glands.

Patterns of breeding behaviour and plasma levels of hormones in a free‐living population of Pied flycatchers, Ficedula hypoleuca

Abstract: Plasma levels of luteinizing hormone (LH) and steroid hormones were measured by radioimmunoassay in a series of plasma samples collected from a free-living population of Pied flycatchers, Ficedula hypoleuca. Both males and females have similar circulating levels of LH and testosterone when they arrive in the breeding area. However, as territories and pair bonds are established, and as courtship and nest-building ensue, the plasma levels of testosterone in males become elevated over those of females, although a lesser peak also occurs in females. As the egg laying phase and incubation begin, plasma levels of LH and testosterone decline sharply in both sexes. On the other hand polyterritorial males, that establish secondary territories, maintain higher levels of LH and testosterone than males remaining in the home-territory, at least until they return to the home-territory, usually at the middle part of the incubation period. By this time polyterritorial males also have basal levels of these hormones. Curiously, females on home-territories show a small, but significant, rise of circulating LH and testosterone at the time the males return. In males, plasma levels of corticosterone are elevated from the time of arrival on the breeding grounds until the end of the nest-building period. Thereafter corticosterone levels decline in males staying on the home-territory but remain elevated in polyterritorial males until the latter return to the home-territory. In contrast, circulating levels of corticosterone in females are only elevated for brief period during egg laying.

Streptococcus mutans, lactobacilli and dental health in 13–14‐year‐old Swedish children

Abstract: The dental health and the prevalence of Streptococcus mutans and lactobacilli were examined in 101 13-114-year-old children. The average number of decayed (incipient caries) and filled surfaces (DFS) was 10.1 and 12.8, respectively. S. mutans was not detected in 11% of the children while 21% had 10(6) or more S. mutans per ml saliva. Lactobacilli were not found in 21% of the children whereas 11% had 10(5) or more lactobacilli per ml saliva. Statistically significant correlations were found between S. mutans and lactobacilli, S. mutans and DFS, lactobacilli and DFS and S. mutans plus lactobacilli and DFS. Increasing numbers of S. mutans and lactobacilli, alone and in combination, were associated with an increased caries frequency.

Susceptibility of Oral Bacteria to Various Fluoride Salts

Abstract: Oral microorganisms were tested for their susceptibility to various fluoride salts. SnF2 and CuF2 had a better antimicrobial effect than did NaF and NH4F. Low pH enhanced the bactericidal effect of the fluoride salts. The results indicate that the cariostatic effect of fluoride is not due to a selective bactericidal effect on cariogenic bacteria.

The capacity of reduced periodontal tissues to support fixed bridgework

Abstract: The total area of periodontal ligament around the abutment teeth in 60 fixed bridges, inserted in patients treated for advanced periodontal disease, was calculated and compared with the total “periodontal ligament area” of the teeth replaced by politics. The calculations revealed that only in 8% of the bridge restorations did the periodontal ligament area of the abutment teeth equal or exceed that of the replaced teeth. In 57% of the bridge material the periodontal ligament area of the abutments was less than 50% of the anticipated normal ligament area of the pontics. Despite the fact that the periodontal support for the restorations was dramatically reduced, all bridges have functioned properly for 8-11 years and the periodontal tissues around the abutment teeth have not suffered further loss of attachment during the period of maintenance care.

The effect of wheat bran on the absorption of minerals in the small intestine.

Abstract: 1. Studies on mineral absorption were carried out in ileostomy patients using the metabolic balance technique. The effect of wheat bran on the absorption of phosphorus, calcium, magnesium, zinc and iron was studied. The extent of digestion of bran phytate in the stomach and small intestine was also investigated. 2. Eight patients with well established conventional ileostomies were studied during two periods while on a constant low-fibre diet. In the second period, 16 g wheat bran/d (American Association of Cereal Chemists) was added to the diet. The amount of phytate-P, non-phytate-P, Ca, Mg, Zn and Fe was determined in the ileostomy contents and in duplicate portions of the diet. 3. Of the added bran phytate-P 24-61% was recovered in the ileostomy contents. In the bran period a significantly decreased amount of Zn was absorbed, while the apparent absorption of Fe and phytate-P increased and that of non-phytate-P, Ca and Mg remained constant. Due to the mineral content of bran, the relative absorption differed in some respects from the absolute absorption, being decreased for Zn, Mg and phytate-P but unchanged for Ca, Fe and non-phytate-P. 4. It is concluded that phytate is partly digested in the stomach and small intestine or possibly absorbed. Addition of 16 g bran/d to the diet does not seem to impair the mineral absorption from the small intestine except that of Zn.

Fieldfare (Turdus pilaris) breeding success in relation to colony size, nest position and association with Merlins (Falco columbarius)

Abstract: Clutch size, nestling production and breeding success were studied in colonial Fieldfares (Turdus pilaris) in a subalpine birch forest during ten breeding seasons. Reproductive success was highest for central pairs in large colonies; such pairs benefited most from communal defence against nest predators. Fieldfares and Merlins (Falco columbarius) usually bred in association. Fieldfares breeding away from Merlins had lower breeding success than pairs associated with Merlins, which also benefited by reduced nest predation. Fieldfares apparently chose to nest near Merlins, which had already laid eggs when the thrushes started nest-building.

Progesterone and Adenosine 3',5'-Monophosphate Formation by Isolated Human Corpora Lutea of Different Ages: Influence of Human Chorionic Gonadotropin and Prostaglandins

Abstract: From each of 34 women undergoing minilaparotomy at various stages of the luteal phase of the cycle, the corpus luteum (CL) was excised in toto, decapsulated, cut into pieces, and incubated for short time periods (5–120 min). Incubations were carried out in the absence and presence of hCG, prostaglandin F2α (PGF2α), and PGE2, both alone and in combination. Dating of the CL was done meticuously using several parameters. After incubation, the tissue levels of cAMP and the media concentrations of progesterone (P) were determined. The basal P production in vitro was highest in CL of the midluteal phase. hCG stimulated cAMP formation in CL of all ages, with the highest levels of cAMP being produced in CL of the midluteal phase. PGE2 was found to increase cAMP formation and potentiate the hCG effect in young CL, but not in CL of the midluteal phase. PGF2α, alone or in combination with hCG, had no effect on cAMP or P formation in either young or old CL, while in CL of the midluteal phase, PGF2α significantly coun...

The effect of chronic ethanol administration on high affinity3H-nicotinic binding in rat brain

Abstract: The effect of chronic ethanol administration on high affinity3H-nicotinic binding in rat brain was investigated. Chronic ethanol administration for 5 months incuded a significant decrease in the number of specific nicotinic binding sites in the hippocampus, whereas a significant increase in the number of nicotinic binding sites both in the hypothalamus and in the thalamus was found. Similar effects were observed both after administration of a lower concentration (8% W/V) ethanol and a higher concentration (16% W/V) indicating that the duration of the administration seems to be of importance for the biochemical changes observed.

Morphometric analyses of human muscle fiber types

Abstract: Fibers from the m. vastus lateralis of 10 middle-aged men were classified at ultrastructural level according to the appearance of the sarcomeric M-band. The Z-band widths had a two-peak distribution. One peak was due to type 1 fibers (mean 125 +/- 11 nm), the other to type 2 fibers. This latter could be separated into type 2A (101 +/- 9 nm) and type 2B (86 +/- 8 nm). About 83% of the fibers would have been correctly classified on the basis of the Z-band width alone. Mitochondrial volumes differed (type 1 5.6 +/- 0.8, 2A 4.0 +/- 0.8, and 2B 2.8 +/- 0.8%). However, only one third (37%) of the fibers would have been correctly classified if sorted according to this parameter. Mitochondrial volumes in the different fibers were correlated to mitochondrial enzymes, while fiber sizes and numbers were correlated to cytoplasmic variables. The correlations appeared mainly after a training program, suggesting that the relationships between structural and functional parameters are more obvious after adaptation to higher functional demands.