Showing papers by "University of Gothenburg published in 1981"

Osseointegrated Titanium Implants: Requirements for Ensuring a Long-Lasting, Direct Bone-to-Implant Anchorage in Man

Abstract: A total of 2895 threaded, cylindrical titanium implants have been inserted into the mandible or the maxilla and 124 similar implants have been installed in the tibial, temporal or iliac bones in man for various bone restorative procedures. The titanium screws were implanted without the use of cement, using a meticulous technique aiming at osseointegration-a direct contact between living bone and implant. Thirty-eight stable and integrated screws were removed for various reasons from 18 patients. The interface zone between bone and implant was investigated using X-rays, SEM, TEM and histology. The SEM study showed a very close spatial relationship between titanium and bone. The pattern of the anchorage of collagen filaments to titanium appeared to be similar to that of Sharpey's fibres to bone. No wear products were seen in the bone or soft tissues in spite of implant loading times up to 90 months. The soft tissues were also closely adhered to the titanium implant, thereby forming a biological seal, preven...

Influence on periapical tissues of indigenous oral bacteria and necrotic pulp tissue in monkeys

Abstract: In nine monkeys (Macaca fascicularis) the pulps of 78 teeth were aseptically necrotized. Twenty-six of the pulp chambers were kept bacteria-free by sealing, while 52 were infected by the indigenous oral flora. The results were recorded clinically, radiographically and microbiologically at the beginning of the experiment and after 6-7 months. The final examination also included histologic recordings. The initially noninfected root canals were all sterile at the final samplings, indicating that the risk of contamination (including hematogenous) of root canals of this animal is very slight. It was shown that noninfected necrotic pulp tissue did not induce inflammatory reactions in the apical tissues. By contrast, teeth with infected pulp tissue showed inflammatory reactions clinically (12/52 teeth) and radiographically (47/52 teeth). Facultatively anaerobic streptococci, coliform rods and obligately anaerobic bacterial strains were most frequently found. In the final samples the number of obligately anaerobic strains increased. Some microorganisms which were isolated in the initial samples were not detected in the final samples. All infected teeth histologically examined showed strong inflammatory reactions in the periapical region.

The significance of maintenance care in the treatment of periodontal disease.

Abstract: The present investigation was performed to assess the efficacy of a maintenance care program to prevent recurrence of disease in patients subjected to treatment of advanced periodontitis. In addition, the periodontal status was monitored of a group of patients who following the end of active treatment were referred back to genera] practitioners for maintenance care. The material consisted of 90 patients who in 1972 were referred for specialist treatment of advanced periodontal disease. The patients were first subjected to an initial examination including assessment of oral hygiene, gingivitis, probing depths and attachment levels. They were on an individual basis given case presentation, instructed how to practice proper tooth-cleaning methods, their teeth were scaled and eventually the periodontal pockets were treated using the modified Widman technique. During the first 2 months following surgery the patients were recalled once every 2 weeks for professional tooth cleaning. Two months after the end of surgical treatment, the patients were reexamined to provide baseline data. Every third patient was thereafter referred back to the general dentist for maintenance care. Two out of three patients were maintained in a carefully designed and controlled maintenance care program at the university clinic. This program involved recalls once every 2–3 months and included instruction and practice in oral hygiene, meticulous scaling and professional tooth cleaning. The patients were reexamined 3 and 6 years after the baseline examination. The results demonstrated that in patients suffering from destructive periodontitis, a treatment program that involved oral hygiene instruction, scaling, root planing and modified Widman flap procedures resulted in the establishment of clinically healthy gingiva and shallow pockets. Patients who were placed on a carefully designed recall program were over a 6-year period able to maintain excellent oral hygiene standards and unaltered attachment levels. In contrast patients who subsequent to active treatment were not maintained in a supervised program showed obvious signs of recurrent periodontitis at the follow-up examinations.

Evolution of reversed sexual size dimorphism and role partitioning among predatory birds, with a size scaling of flight performance

Abstract: To explain the adaptive significance of sex role partitioning and reversed sexual size dimorphism among raptors, owls and skuas, where females are usually larger than males, we combine several previous hypotheses with some new ideas. Owing to their structural and behavioural adaptations for prey capture, predatory birds have better prospects than other birds of defending their offspring against nest predators. This makes sex role partitioning advantageous; one parent guards the offspring while the other forages for the family. Further, among predators hunting alert prey such as vertebrates, two mates because of interference may not procur much more food than would one mate hunting alone. By contrast, two mates feeding on less alert prey may together obtain almost twice as much food as one mate hunting alone. For these reasons, partitioning of breeding labours might be adaptive only in predatory birds. An initial imbalance favours female nest guarding and male foraging: the developing eggs might be damaged if the female attacks prey; their mass might reduce her flight performance; she must visit the nest to lay; and the male feeds her before she lays (‘courtship feeding’). Increased female body size should enhance egg production, incubation, ability to tear apart prey for the young, and, in particular, offspring protection in predatory birds. Efficient foraging during the breeding period then becomes most important for the male. This imposes great demands on aerial agility in males, particularly among predators of agile prey. Flight performance decreases with increasing size in five of six aspects explored. The male must therefore not be too large in relation to the most important prey. For these reasons, he should be smaller than the female. Among predatory birds, size dimorphism increases with the proportion of birds in the diet, which may be explained as follows. Adult birds have mainly one type of predators: other predatory birds. Because almost only these specialists exploit adult birds, they carry out most of the cropping of this prey. A predator of easier prey competes with many other kinds of predators, which considerably reduce prey abundance in its territory. This is not so for predators of adult birds. Further, because birds are extremely agile, the specialized predator can hunt efficiently only within a limited size range of birds, whose flight skill it can match. Increased size dimorphism among these predators therefore should be particularly important for enlarging the combined food base of the pair. A bird specialist may consume much of the available prey in the suitable size range during the breeding period. When the predator's young are large enough to defend themselves, the female aids better by hunting than by guarding the chicks. It is advantageous among bird specialists if she hunts prey of other sizes than does the male, who has by then reduced prey abundance in his prey size class. But among predatory birds hunting easier prey the female gains little by hunting outside the male's prey spectrum, because other kinds of predators will have reduced the prey abundance outside as well as inside the male's preferred size range. Intra-pair food separation through large sexual size dimorphism therefore should be particularly advantageous among predators of birds. This may be the main reason why the degree of size dimorphism increases with the dietary proportion of birds.

Effects of a new type of 5-HT receptor agonist on male rat sexual behavior

Abstract: 8-Methoxy-2-(di-n-propylamino) tetralin (8-OMe-DPAT) and 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) are two new drugs exerting selective actions on brain 5-HT neurotransmission. In the present experiments we have investigated the effects of these two drugs on male rat sexual behavior. It was found that both drugs reduce the number of intromissions preceding ejaculation and shorten the ejaculation latency. These effects are extremely pronounced and several animals ejaculate at the first intromission. In addition 8-OH-DPAT produced a slight reduction of the post-ejaculatory interval. There were no significant effects on latency to initiate copulation or in the number of mounts preceding ejaculation. Finally, sexual behavior was partly or completely restored in castrated male rats after injection with 8-OMe-DPAT or 8-OH-DPAT.

Sedimentation and sulfate reduction under a mussel culture

Abstract: The sedimentation and dissimilatory sulfate reduction under a blue-mussel culture were quantified in order to gain information on the environmental impact of intense mussel farming. The sedimentation rate (3 g C·m-2·d-1) under a culture is nearly three times higher than at a nearby reference station. A build-up of sediment rich in organic material and sulfide takes place under the mussels. At 15°C the sulfate reduction rate was 30.5 mmol SO = 4 ·m-2·-1 in the upper 10 cm of the mussel sediment. The increase in sedimentation under a mussel culture and the consequent effects should be considered when establishing mussel farms.

On the Role of Intramural Nerves in the Pathogenesis of Cholera Toxin-induced Intestinal Secretion

Abstract: Intestinal secretion was produced in anesthetized cats and rats by exposing isolated intestinal segments to cholera enterotoxin. Giving, for example, tetrodotoxin, a nerve-conduction-blocking agent, or adding lidocaine, a local anesthetic agent, to the solution in the intestinal segments markedly inhibited the rate of choleraic secretion, and in most experiments a net absorption of fluid was observed. The results suggest that intramural nervous mechanisms are involved in the pathogenesis of choleraic secretion.

Molecular cloning of the complete Epstein-Barr virus genome as a set of overlapping restriction endonuclease fragments

Abstract: A complete collection of fragments of Epstein-Barr virus DNA, obtained by cleavage with restriction endonuclease Eco RI, has been cloned. Fourteen different internal fragments of the virus genome, derived from linear virion DNA of the B95-8 strain, and sequences corresponding to the terminal regions of virion DNA, derived from intracellular circular EBV DNA isolated from 895-8 cells, were cloned. Sizes of fragments were determined by agarose gel electrophoresis and their sum leads to an estimated molecular weight of 110 x 10(6) for virion DNA. Large Eco RI DNA fragments of special interest were also cloned in cosmids using another source of EBV DNA, that is, to circular viral DNA derived from Raji cells. In order to provide a set of overlapping sequences, all the 29 internal Bam HI fragments of B95-8 virion DNA were cloned in pBR322. The map location within the viral genome of each cloned DNA fragment was identified by hybridizing to blots of virion DNA cleaved with several different restriction endonucleases.

Healing following surgical treatment and root demineralization in monkeys with periodontal disease

Abstract: The aim of the present investigation was to study the potential for new attachment to root surfaces which 1) had become devoid of attachment either by mechanical removal or in conjunction with experimental periodontal tissue breakdown and 2) subsequently had been conditioned with citric acid. Three adult monkeys (Macaca cynomolgus) were used. Periodontal pockets were produced during a 2–6-month period around the maxillary central incisors and first and second premolars and around the mandibular central incisors by the placement of orthodontic elastics. Surgical treatment of the pockets was carried out with the use of a flap procedure. During surgery, the roots of the premolars on the right side of the jaws were first scaled and planed and subsequently treated with citric acid. Citric acid conditioning was not performed on the premolars of the left side. In the front tooth regions the surgical treatment included citric acid conditioning of the mandibular central incisors in two animals and of the maxillary central incisors in one animal. Surgical procedures were also carried out around the mandibular second premolars and first molars which had not been exposed to periodontal tissue breakdown. Folio wing flap elevation, the buccal bone plate was mechanically removed within an area corresponding to that of bone loss produced by the experimental periodontitis model in the maxillary premolars. The cementum layer of the surgically denuded portion of the roots was removed by root planing. In all treated teeth, a notch was prepared in the buccal root surfaces at the level of the alveolar bone crest. Six months following treatment the animals were sacrificed and histologic sections prepared. Linear measurements were made along the root surface from the apical border of the prepared notch to the apical termination of the junctional epithelium and to the crest of the alveolar bone. The results demonstrated that cementum formation and new connective tissue attachment did not occur on root surfaces previously exposed to periodontal pockets and subsequently subjected to scaling and root planing or on root surfaces surgically deprived of their supporting bone and previously “non-exposed” cementum layer. Cementum formation and new connective tissue attachment also failed to occur following citric acid conditioning of root dentin surfaces. In all sections representing all three treatment groups, the attachment between the gingiva and the root was established by epithelium.

Effect of chlorhexidine gel treatment on Streptococcus mutans population in human saliva and dental plaque

Abstract: – The effect of topical application of a 1% chlorhexidine gel on the population of S.mutains in dental plaque and saliva was studied in five subjects highly infected with the organism. After treatment for 5 min daily for 14 d, S. mutans was not detected in three of the subjects and counts of 700 colony-forming units or less per ml of saliva were found in the other subjects. Reappearanceof S. mutans was slow and did not reach pretreatment level until 14 weeks or more after therapy. The proportion of S. saguis in plaque increased temporatrily after chlorhexidine treatment, whereas the population of lactobacilli was unaffected. These observations indicate that short-term use of chlorhexidine is of value in controlling oral infection of bumans by S. mutans.

Streptococcus mutans in plaque and saliva and the development of caries

Abstract: — Plaque samples from 10 different tooth surfaces of 10 schoolchildren with Varied Caries experience (DFS 10-33) were collected five times during 2.5 years. The samples were examined with an immunofluorescent technique for identification and enemeration of Sreptococcus mutans scrotypes C/e/f and d/g. At each sampling occasion the children were scored for caries. A Stimulated saliva sample was also collected and the number of S. mutans per ml salva was determined. The salva level of S. Mutans was Shown to reflect the prevalence and proportion of this microorganism on theselected surfaces. Five surfaces carried S. nutans at each sampling. Four of these surfaces showed progressive caries. S. mutans infection was also found to precede the development of incipient caries on four surfaces. Eighty percent of the surfaces that stayed sound were only transiently carrriers of S. mutans in mainly very low numbers. Serotype c/e/f dominated in prevalence and proportion on the surfaces with a history of caries during the study.

A Model for the Thickness and Salinity of the Upper Layer in the Arctic Ocean and the Relationship between the Ice Thickness and Some External Parameters

Abstract: This paper presents a dynamical model for the salinity and thickness of the upper layer in the Arctic. The parameters are the river runoff to the Arctic, the buoyancy supply through the Bering Strait, the export of ice from the Arctic and a parameter characterizing the vertical mixing. An ice model is formulated, having the following two important properties: 1) the horizontal surface area of the exported ice is essentially determined by external parameters (the wind field over the Arctic); and 2) there is a relationship between the ice thickness and the fraction of open water in the Arctic. The model for the upper layer and the ice model are used together with a heat budget for the Arctic, also including the effect of different albedo for ice and open water. A relationship between the freshwater supply and the ice thickness is derived. Also investigated are the effects on the ice thickness of a changed export of ice area and changed properties of the flow through the Bering Strait. It is found t...

Binding Specificity of Piliated Strains of Escherichia coli and Salmonella typhimurium to Epithelial Cells, Saccharomyces cerevisiae Cells, and Erythrocytes

Abstract: The binding to mammalian cells of piliated enteric bacteria and the inhibition of the binding by antibodies to purified pili were studied. The target cells were epithelial cells from human bucca and human and rat urinary tracts, erythrocytes from various species, and Saccharomyces cerevisiae cells. The strains were selected to represent the two main agglutination patterns of enteric bacteria: mannose-resistant agglutination of human and other erythrocytes and mannose-sensitive agglutination of guinea pig and other erythrocytes. Escherichia coli 3669 caused only mannose-resistant agglutination, E. coli 6013 caused only mannose-sensitive agglutination, and E. coli 3048 caused both types of agglutination simultaneously. Salmonella typhimurium SH6749 exhibited only mannose-sensitive hemagglutination and was included to allow comparison of its pili with those of E. coli strains. The range of epithelial cells to which the bacteria adhered was related to their agglutination patterns. All four strains attached to human buccal cells. Only E. coli strains 3669 and 3048, which caused mannose-resistant agglutination, adhered to human urinary tract epithelial cells, and only those strains that caused mannose-sensitive agglutination adhered to rat urinary tract epithelial cells. The binding of S. typhimurium SH6749, but not of the other strains with mannose-sensitive agglutination, was significantly inhibited by d-mannose. Globotetraosylceramide, a glycolipid present in the human urinary tract epithelium, inhibited attachment to human uroepithelial cells of the two strains with mannose-resistant hemagglutination. As tested by the enzyme-linked immunosorbent assay, cross-reactions between type 1 pili of the E. coli strains were strong, but those between S. typhimurium and E. coli mannose-sensitive pili were weak. The two pili that induced mannose-resistant hemagglutination on E. coli did not cross-react. Significant inhibition of adhesion of all four strains was obtained with the homologous anti-pilus antiserum. The binding of bacteria to mammalian cells may thus be mediated by several types of bacterial pili reacting with different receptors on mammalian cells.

The bone-anchored auricular episthesis.

Abstract: Total ablation of the pinna gives an unsatisfactory cosmetic result which has to be corrected. Plastic surgery procedures are generally not very successful and some sort of episthesis is preferred by many. The attachment of an episthesis is, however, often a problem. This paper is a case report of a new type of episthesis fixation arrangement. In a first session four titanium screws were implanted into the temporal bone above and behind the external meatus with a technique ensuring minimal tissue violation. Three months later when these screws were firmly integrated in the living bone, skin-penetrating titanium abutments were connected and a gold bridge was adapted to the abutments. A silicon rubber episthesis was attached to the bridge with a snap fastener. Behind this new method of episthesis attachment are several years of clinical experience of titanium implants directly anchored into various living bones and allowed to permanently penetrate skin or mucous membrane.

Role of keratinized gingiva for gingival health. Clinical and histologic study of normal and regenerated gingival tissue in dogs.

Abstract: The present study was carried out in the Beagle dog in order to determine if variations of the width of the zone of keratinized gingiva occur in the canine dentition, if the width alters during the development of destructive periodontitis and if, subsequent to surgical excision of the periodontal lesion, the regenerated gingival margin differs from that of a normal, noninflamed gingiva. Five dogs were used. A baseline examination comprised assessments of dental plaque, gingival conditions and width of the zone of keratinized gingiva. Cotton floss ligatures were placed around the teeth on the right side of the jaws and plaque was allowed to accumulate in order to induce periodontal tissue breakdown. After 150 days the inflamed periodontal tissues around the experimental teeth were removed surgically using a “gingivectomy” or a flap procedure. In the “gingivectomy” procedure the entire zone of the keratinized gingiva was excised whereas the main part of the keratinized tissue was maintained with the flap procedure. During a healing period of 120 days plaque control was carried out daily. On the left side of the jaws (control side) a careful toothcleaning program was performed during the entire observation period of 270 days. Clinical examinations of all control and experimental tooth units were repeated on days 150 and 270. Biopsies were sampled from both sides of the jaws on day 270. In histological sections the free gingival tissue was subjected to histometric assessments and a stereologic analysis based on a standardized morphometric point-counting procedure. In addition, the number of leukocytes residing within the junctional epithelium was determined. The results showed that in Beagle dogs the width of the keratinized gingiva (WKG), on the facial aspect of premolars and molars, varies between 2 and 6 mm. During a period of 270 days of careful plaque control, the WKG was maintained unaltered. In comparison, a phase of experimental periodontitis resulted in a substantial decrease of the WKG. Subsequent to the excision of the inflamed periodontal tissues, which in some cases included the entire zone of the keratinized gingiva, a new free gingival unit developed. In most respects the structural composition of this regenerated gingival unit was similar to that of a normal control unit. Furthermore, in the absence of plaque, the regenerated soft tissue was free from signs of inflammation independent of presence or absence or width of the keratinized zone.

A mechanism governing the estuarine circulation in deep, strongly stratified fjords

Abstract: The estuarine circulation in deep, strongly stratified fjords is discussed. It is argued that a two-layer description of the stratification in the fjord is correct in very wide fjords (wide compared to the width of the mouth) and possibly also in narrow fjords with high runoff and/or weak mixing. A theory for the thickness and the salinity of the brackish layer in a wide fjord was earlier developed by the present author (and published in Swedish, 1975) and it is presented here. Among other findings in that theory we may mention that the thickness of the brackish layer is primarily determined by the internal hydraulic control for high specific runoff (runoff/unit horizontal surface area of the fjord) and weak mixing. In the other extreme, with low specific runoff and strong mixing, the thickness of the brackish layer is found to be proportional to the Monin-Obukhov length. The circulation in not very wide fjords is also discussed. It is found that recirculation in the brackish layer may be expected whereby a two-layer description of the flow field breaks down at least locally. A critical Rayleigh number that seems to control the recirculation of brackish water within the fjord is found. A theory for the density difference between the mouth and the head in the brackish layer in the fjord is developed from the critical Rayleigh number condition. It is found that this density difference normally is proportional to the density difference between the brackish water at the mouth and the underlying sea water provided that the river runoff is not too heavy and/or the mixing is not too weak. This prediction is confirmed by extensive measurements from the Nordfjord.

Effect of oral hygiene instruction and professional toothcleaning on caries and gingivitis in schoolchildren.

Abstract: The preset study was performed to assess the effect on caries and gingivitis of plaque control measures such as oral hygiene instruction, toothcleaning practice and professional toothcleaning. 104 children, 13-14 years old, participated in the trial. Prior to the start of the preventive treatment all children were examined regarding oral hygiene, gingivitis and caries. The caries examintion was limited to the proximal surfaces of molars and premolars. Following this baseline examination the children were randomly divided into two treatment groups A, and B. Both groups of children were recalled for professional toothcleaning once every 2 weeks during an 18-month period. In each child the professional toothcleaning was restricted to either the right or the left jaws by random selection. In addition, the children of Group A at each recall appointment received careful oral hygiene instruction and practice in proper toothcleaning methods. In conjunction with the professional toothcleaning an abrasive paste was used including fluoride. The children were re-examined 18 months after the baseline examination. The result of the present investigation demonstrated that professional toothcleaning repeated every second and week is a prophylactic measure which in children substantially improves the oral hygiene status, and effectively reduces clinical signs of gingivitis and caries. It was also observed that while oral hygiene instruction and practice in proper toothcleaning techniques reduced plaque and gingivitis, no such effect could be detected regarding the development of caries.

Fat inhibition of gastric acid secretion in man and plasma concentrations of neurotensin-like immunoreactivity.

Abstract: The effects of intraduodenal administration of oleic acid (5, 10, 20, and 40 ml) on gastric acid secretion stimulated by a submaximal intravenous pentagastrin infusion and on plasma concentrations on neurotensin-like plasma immunoreactivity (NTLI) were studied in 18 healthy subjects. Each volume of oleic acid or saline (controls) was tested in six subjects except the volume of 20 ml, which was given to ten subjects. Gastric acid secretion was studied for a 2-h period at 15-min intervals after intraduodenal infusion. Five milliliters oleic acid evoked a significant inhibition (29%) of gastric acid secretion. Maximal inhibition by oleic acid appeared after 20 ml (43%), which was significantly greater than after 10 ml. In seven duodenal ulcer (DU) patients 20 ml oleic acid evoked an inhibition of 20%, which was significantly lower than in the healthy subjects. Proximal gastric vagotomy (PGV) abolished the fat inhibition in DU patients. Basal and peak NTLI concentrations after 20 ml oleic acid were significan...

Five‐year mortality in a 70‐year‐old urban population in relation to psychiatric diagnosis, personality, sexuality and early parental death

Abstract: In 1971–1972 a systematic, representative sample of 70-year-olds living in Gothenburg, Sweden, was studied. The study included a psychiatric examination, during which the subjects were questioned concerning important aspects of their life history, and mental symptoms during the previous month. Any mental signs observed were recorded. Symptoms and signs were rated on rating scales, and summed up in diagnoses. The subjects also filled in three different personality inventories. The examination was performed in 166 men and 226 women. In 1976–1977 we ascertained from parish records which subjects had died before reaching the age of 75. Thirty-two men and 23 women had died. Associations between the psychiatric variables and mortality were studied. There was a positive association in men between mortality and organic psycho-syndromes. There was a positive, but nonsignificant association with indications of previous alcohol abuse. There was no association with anxiety, depressive and obsessive compulsive neuroses or with personality deviations and few associations with personality dimensions and psychogenic needs. There was a positive association in married men between mortality and early cessation of sexual intercourse. There was also a positive association in men between mortality and loss of parents by death before the age of 16.

Effects of occlusal treatment and intraarticular injections on temporomandibular joint pain and dysfunction.

Abstract: The long-term effect (2 years) of occlusal treatment and intra-articular injections of a mixture of corticosteroid and local anaesthetic was investigated in two groups of patients with pain and dysfunction in the temporomandibular joint (TMJ). Fifteen patients were treated with injections and eighteen patients with occlusal adjustment. The TMJ was tender to palpation in all patients. The intra-articular injections were given once a week for three weeks. The occlusal treatment included splints, grinding on natural teeth and occlusal correction of complete dentures. The severity of the subjective symptoms and clinical signs was estimated before and after treatment. Both sorts of treatment reduced the subjective symptoms and the clinical signs significantly, but the reduction was significantly greater after the intra-articular injections. The effect of the injections was less efficient in patients with radiographic signs of remodelling of the TMJ and general joint symptoms. It was concluded that both intra-articular injections of corticosteroid combined with local anaesthetic and occlusal treatment have a long palliative effect on TMJ pain and dysfunction. The intraarticular treatment, however, had a greater effect on the clinical signs.

Food information in the Black-headed Gull, Larus ridibundus

Abstract: The ‘information-centre’ hypothesis suggests that bird colonies function as sources of information about good feeding sites, to which unsuccessful birds may follow foragers. One assumption of the hypothesis is that unusually successful foragers are followed by other colony members when returning to a newly found, rich food source. We tested this assumption in a colony of Black-headed Gulls (Larus ridibundus). Parents feeding their young from a rich, artificial food source were observed on their return trips to the feeding site. In none of 50 cases did other colony members follow them to the newly found food. However, the gulls were attracted to groups of foraging conspecifics. In experiments with paired food piles and a group of model gulls at one pile in each pair, Black-headed Gulls always alighted first at the piles with models. Hence the information-centre mechanism was refuted, but the gulls did acquire food information from each other in another way.

Fracture of the Capitulum Humeri

Abstract: Fractures of the capitulum humeri are rare and the recommendations for treatment differ. Some authors recommend open reduction of the capitular fragment, while others advocate excising it. Twelve patients with anterior shearing fractures of the capitulum humeri were treated as inpatients in the Departments of Orthopaedic Surgery, Gothenburg, during the years 1973-1977. Ten patients, all treated with open reduction and internal fixation of the capitular fragment, were re-examined. The functional result was estimated as good in nine and poor in one.

Isolation and Partial Characterization of the Lipoprotein Families A and A‐I from High‐Density Lipoproteins of Human Serum

Abstract: Procedures for the isolation of two lipoprotein fractions from plasma high-density lipoproteins (HDL), characterized by apolipoprotein A-I and apolipoprotein A-I together with apolipoprotein A-11, have been elaborated. Apolipoprotein A-I was identified as the protein moiety of one of these fractions (lipoprotein A-I) with polyacrylamide gel electrophoresis (at basic and acidic pH, as well as in the presence of sodium dodecyl sulphate), immuno-double-diffusion, and amino acid analysis. Apolipoproteins A-I and A-I1 were identified as the protein moiety of the other fraction (lipoprotein A) with polyacrylamide gel electrophoresis (basic and acidic pH) and immuno-double-diffusion. Lipoprotein A-I consisted of spherical particles with a diameter similar to that of HDL as judged from negative stains in the transmission electron microscope. The diameter was estimatcd lo be 8.7 nm from gel chromatography. Lipoprotein A-I migrated in the HDL position on crossed immunoelectrophoresis. On iso-electric focusing lipoprotein A-I appeared as multiple bands in the pH range 5.05 - 5.55. Lipoprotein A-I had the density of an HDL-2 fraction (Q : 1.063 - 1.105). Lipoprotein A consisted of spherical particles with a diameter similar to that of HDL, as judged from negative stains in the transmission electron microscope. The diameter was estimated to be 7.9 nm from gel chromatography. The molar ratio between the A-I and A-I1 polypeptides was estimated to 1.3 : 1 with electroimmunoassay and calculations from the amino acid compositions. Lipoprotein A migrated in the position of HDL on crossed immuno-electrophoresis. On isoelectric focusing lipoprotein A appeared as one major and two minor bands in the pH range 5.10-5.30. Lipoprotein A had the hydrated density of an HDL-2 fraction. The protein moiety of the plasma lipoproteins consists of several non-identical polypeptides [l - 61. According to the terminology of the plasma lipoprotein family concept [7] these polypeptides are referred to as apoA-I, A-11, apoB, apoC (composed of the C-I, C-I1 and C-I11 polypeptides), apoD, apoE and apoF and the corresponding lipoprotein families as Lp-A, Lp-A-I, Lp-B, Lp-C, Lp-D, Lp-E and Lp-F. The major apolipoproteins of the high density lipoprotein (HDL) region are apoA-I and A-I1 while apoB, apoC, apoD, apoE and apoF are quantitatively minor protein constituents [6,8]. Several observations indicate that apoA-I and A-I1 occur together on the same lipoprotein particles forming Lp-A [9 - 1 I]. The presence of a lipoprotein particle containing apoA-I as protein moiety has been suggested earlier [I 1 - 131, but no reproducible isolation procedure has been reported so far. In this paper we present reproducible methods for the isolation of lipoprotein particles belonging to the lipoprotein families Lp-A-I (containing apoA-I as protein moiety) and Lp-A (containing apoA-I and A-I1 as protein moiety).