Showing papers by "Aarhus University published in 1975"
TL;DR: The postnatal development of the hard palate was studied by conventional histologic and microradiographic means on autopsy material and indicated the growth in length until the age of 13 to 15 was due to growth in the transverse suture and to apposition on the posterior margin of the palate.
430 citations
TL;DR: In this article, the Ward-Takahashi identities for scalar electrodynamics in Fermi gauges are shown to imply a homogeneous first-order partial differential equation for the effective potential involving only the gauge parameter and the external scalar field.
416 citations
TL;DR: It is concluded that the regions of the large chain exposed in the presence of K+ are distinct from the regions exposed in presence of Na+ and that two conformations of (Na+, K+)-ATPase can be sensed with trypsin, a (T)K-form and a (t)Na-form.
309 citations
TL;DR: The study has revealed that candida infection and poor denture cleanliness are very common in elderly denture wearers.
Abstract: The purpose of this study has been to assess the prevalence of denture stomatitis and candida infection in an elderly Danish population. Ten percent of the population above the age of 65 in a Danish community was selected randomly. The study group consisted of 465 persons wearing a removable maxillary denture, who were examined in their homes. Yeasts were isolated by oral swabs for cultivation and by mucosal and denture scrapings for microscopy. The prevalence of denture stomatitis was 65%. Yeasts, especially C. albicans, were cultivated in most denture wearers with denture stomatitis (Group 1) or with clinically normal palatal mucosa (Group 2). However, large accumulations of hyphae were present in 77% of the patients in Group 1 compared with 47% in Group 2; both hyphae and inflammatory cells were seen in smears in 65% of Group 1 but only in 14% of Group 2. On the other hand, bacterial contamination of the smears was more pronounced in Group 2 than in Group 1. The study has revealed that candida infection and poor denture cleanliness are very common in elderly denture wearers.
276 citations
TL;DR: It is concluded that the destruction ofglomeruli due to diabetic microangiopathy is compensated for some years by hypertrophy of the least affected glomeruli, which might well account for the preservation of renal function in long-term diabetics for a number of years despite the progressive basement membrane lesions of diabetic microANGiopathy.
Abstract: A study of autopsy kidney material from six long-term diabetics and four controls was performed in order to elucidate the mechanism of the glomerular enlargement in long-term diabetics. The volume and the severity of the glomerular lesion were measured in each of a number of randomly selected, open glomeruli. The relative amount of solid material was taken as an expression of the severity of the glomerular lesion. In the long-term diabetics the volume of open glomeruli was almost doubled compared to that of controls and in the individual subject the enlargement was found to be inversely related to the relative amount of solid material in the glomeruli. This indicates that the enlargement of open glomeruli in long-term diabetics is due to a compensatory hypertrophy rather than to the excessive deposition of basement membrane material. The number of nuclei per open glomerulus was increased in long-term diabetics, but nuclear size was unchanged. Most of the long-term diabetics had a large number of occluded glomeruli, and the individual, relative number of such glomeruli correlated closely both with the duration of diabetes above 15 years and the concentration of creatinine in serum. It is concluded that the destruction of glomeruli due to diabetic microangiopathy is compensated for some years by hypertrophy of the least affected glomeruli. This compensatory hypertrophy of glomeruli might well account for the preservation of renal function in long-term diabetics for a number of years despite the progressive basement membrane lesions of diabetic microangiopathy.
250 citations
TL;DR: The size ratio between the coexisting species usually found (1.3–1.5) allows stable coexistence based on food praticles size selectivity alone and Potamopyrgus jenkinsi does not show character displacement when coexisting with, e.g., H. ventrosa.
Abstract: Populations of coexisting and of allopatrically occurring species of hydrobiid snails (Hydrobia ulvae, H. neglecta, H. ventrosa and Potamopyrgus jenkinsi) have been studied in 90 localities within three different areas. When H. ventrosa coexists with H. ulvae they show character displacement, i.e., the average body size of the former is smaller and that of the latter is larger. When these species live alone they are of approximately the same size. It is shown here that the size ratio between the coexisting species usually found (1.3–1.5) allows stable coexistence based on food praticles size selectivity alone. Variation in the degree of character displacement from locality to locality is explained by different degrees of genetical isolation of the populations. Coexisting H. ventrosa and H. ulvae have shorter, more well-defined periods of reproduction than they do when they occur alone. H. neglecta is larger than coexisting H. ventrosa and smaller than coexisting H. ulvae. Due to the patchy distribution and the fluctuating populations of this species, and due to the fact that pure H. neglecta populations are rare, data on this species are difficult to interpret. Potamopyrgus jenkinsi shows a different food particle size selection than the Hydrobia spp. of identical sizes. Competitive interactions between P. jenkinsi and coexisting Hydrobia spp. are therefore probably weak. In accordance with this, P. jenkinsi does not show character displacement when coexisting with, e.g., H. ventrosa.
234 citations
TL;DR: The prominent finding of this extended serologic analysis on American and African Kaposi's sarcoma patients and appropriately matched control groups is the detection of a specific serologic association of cytomegalovirus (CMV) with American KS patients.
Abstract: The prominent finding of this extended serologic analysis on American and African Kaposi's sarcoma (KS) patients and appropriately matched control groups is the detection of a specific serologic association of cytomegalovirus (CMV) with American KS patients. All American KS sera contained CMV antibodies and their geometric mean titers (GMT) were significantly higher than those in sera of melanoma patients (GMT ratio k = 5.3 to 7.7 by complement fixation [CF], k = 8.9 by indirect hemagglutination [IHA]) or in sera of age- and sex-matched healthy controls (k = 12.6 to 16.0 by CF, k = 12.6 by IHA). The result is strongly reminiscent of the data obtained previously for European KS. Although the GMT to CMV of African KS patients were similar to the GMT of the American KS groups, their significance cannot be demonstrated due to the high background of CMV infections in the control groups. Complex mechanisms are hypothesized, by analogy with the Epstein-Barr virus (EBV) involvement in Burkitt's lymphoma (BL), for a CMV involvement in the development of KS.
228 citations
TL;DR: The results support further the concept that there is a basal connection between enlarged kidneys and the elevated GFR of early diabetes.
Abstract: Glomerular filtration rate (GFR), renal plasma flow (RPF) and roentgenographic kidney size were measured in six newly diagnosed male diabetics with a mean age of 25 years. Glomerular filtration rate was elevated before treatment to the same extent as found previously. A significant fall in both kidney size and glomerular filtration rate was found after treatment with insulin for 3 months. These results support further the concept that there is a basal connection between enlarged kidneys and the elevated GFR of early diabetes.
221 citations
TL;DR: The ATPase activities of both the myofibrils and actomyosin preparations are considerably higher than previously described for vertebrate smooth muscle and are sensitive to micromolar Ca2+ ion concentrations to the same degree as comparable skeletal and cardiac muscle preparations, even though troponin-like proteins could not be identified in these smooth muscle preparations.
Abstract: A new technique for obtaining a myofibril-like preparation from vertebrate smooth muscle has been developed. An actomyosin can be readily extracted from these myofibrils at low ionic strength and in yields 20 times as high as previously reported. The protein composition of all preparations has been monitored using dodecylsulfate-gel electrophoresis. By this method smooth muscle actomyosin showed primarily only the major proteins, myosin, actin and tropomyosin, while the myofibrils contained, additionally, three new proteins not previously described with polypeptide chain weights of 60000, 110000 and 130000. The ATPase activities of both the myofibrils and actomyosin preparations are considerably higher than previously described for vertebrate smooth muscle. They are sensitive to micromolar Ca2+ ion concentrations to the same degree as comparable skeletal and cardiac muscle preparations, even though troponin-like proteins could not be identified in these smooth muscle preparations. From the latter observation and the presence of Ca2+-sensitivity in tropomyosin-free actomyosin it is suggested that this calcium sensitivity is, as in some invertebrate muscles, a property of the myosin molecule.
211 citations
TL;DR: It is concluded that the number of coexisting, closely related species is usually small, and that their resource partitioning is probably mainly based on particle-size selectivity, which explains some qualitative differences in the composition of the food of the two forms.
Abstract: The feeding biology of the deposit-feeding amphipod Corophium volutator is compared to that of the coexisting, deposit-feeding prosobranch Hydrobia ulvae. Regarding ingestion of particles, both forms show size selection which alone can explain their coexistence. Particle size-selection also explains some qualitative differences in the composition of the food of the two forms; thus, diatoms play a relatively larger role in the diet of H. ulvae than in the diet of c. volutator, whereas bacteria are probably relatively more important for the latter. Results of experiments with feeding of C-14 labelled microorganisms are in accordance with the findings on particle size-distribution of the gut contents, and show that (1) C. volutator can only utilize bacteria adsorbed to particles within the size range 4 to 63 μ (this is why the presence of clay and silt particles in the sediment are necessary for efficient feeding of this amphipod); (2) C. volutator can utilize bacteria suspended in the water pumped through its burrow for respiration if silt and clay particles are present in the sediment. (3) H. ulvae can utilize large particles, and also browses on surfaces, and some evidence is brought forward that it also utilizes mucus for trapping microorganisms. The coexistence of deposit-feeding animals is discussed. It is concluded that the number of coexisting, closely related species is usually small, and that their resource partitioning is probably mainly based on particle-size selectivity. In the case of unrelated forms (e.g. H. ulvae and C. volutator, a number of behavioural, physiological and morphological differences, and also the widespread ability of deposit feeders to utilize alternative feeding mechanisms may also lead to resource partitioning. Thus, there are often several niche dimensions related to feeding allowing a certain diversity of coexisting deposit feeders.
210 citations
TL;DR: In this paper, a new method for determining the optimal α which computationally has proved more efficient than the Golub-Pereyra scheme was proposed, which can be reduced to a nonlinear least square problem involving α only, and a linear least squares problem involvinga only.
Abstract: Consider the separable nonlinear least squares problem of findinga eR
n
and α eR
k
which, for given data (y
i
,t
i
),i=1,2,...m, and functions ϕ
j
(α,t),j=1,2,...,n(m>n), minimize the functional
$$r(a,\alpha ) = \left\| {y - \Phi (\alpha )a} \right\|_2^2$$
where θ(α)
ij
=ϕ
j
(α,t
i
). Golub and Pereyra have shown that this problem can be reduced to a nonlinear least squares problem involvingα only, and a linear least squares problem involvinga only. In this paper we propose a new method for determining the optimalα which computationally has proved more efficient than the Golub-Pereyra scheme.
TL;DR: In this paper, a mathematical model for the room air concentration of formaldehyde has been established, where the average concentration was 0.62 and the range 0.08-2.
TL;DR: Evidence is reported for the photosystem I-driven CO2 photoassimilation in O. limnetica with H2S serving as sole electron donor through oxidation to elemental sulphur.
Abstract: PROFOUND differences in structure and function separate the prokaryotic cyanobacteria (blue-green algae) from eukaryotic algae and plants, whereas oxygenic photosynthesis is considered to distinguish the cyanobacteria and eukaryotic plants from the other phototrophic bacteria. The prevailing concepts on the cyanobacteria emphasise their prokaryotic nature and oxygenic photosynthesis. This combination of properties, among others, led to the suggestion that the cyanobacteria represent a group of possible progenitors of chloroplasts1. While cyanobacteria typically exhibit oxygenic photosynthesis with two photosystems using electrons from water, it has been demonstrated that photosystem I of certain cyanobacteria can function in vivo independently in supporting virus production2, heterocyst functions3 and even photoheterotrophic growth4. We have demonstrated anoxygenic photosynthesis in a cyanobacterium Oscillatoria limnetica, also capable of oxygenic photosynthesis, which was isolated from the anaerobic H2S rich hypolimnion layer of the monomictic, hypersaline Solar Lake located on the desert margin of the Gulf of Elat, Israel5. During winter stratification, this layer is located below two plates of phototrophic sulphur bacteria (Chromatium violescens and Prosthecochloris sp.), and exhibits a dense cyanobacterial bloom with very high rates of primary production. We report here evidence for the photosystem I-driven CO2 photoassimilation in O. limnetica with H2S serving as sole electron donor through oxidation to elemental sulphur.
TL;DR: It is conjectured that the distribution of the species results from the interaction of habitat selection, dispersal rates, colonizations, interspecific competition and extinctions, as well as the possibility of coexistence between competing species as a result of migrations between different habitats.
Abstract: The distribution patterns of four species of mud snails (Hydrobiidae) in a complex, estuarine environment are described. The species show habitat selection with respect to salinity but the tolerance ranges of the species overlap and it is shown that this factor alone cannot predict the distribution in the field. The found patterns show that the species are subdivided into many, more or less isolated sub-populations. It is conjectured that the distribution of the species results from the interaction of habitat selection, dispersal rates, colonizations, interspecific competition and extinctions. This interpretation explains features of the distribution patterns; e.g., the boundaries between two species in salinity gradients occur at different salinities in different areas, the species with an intermediate position with respect to salinity preference is the least frequent one, and that coexistence between two, and sometimes three species may occur under certain conditions. The possibility that the species may sustain populations within some areas as “fugitive” species is also discussed.
TL;DR: In this paper, the gross theory of β-decay is applied to make improved estimates of the absolute magnitude of βdecay half-lives and related variables in the r-process calculation.
TL;DR: Macoma nasuta Conrad is primarily a deposit-feeding bivalve sucking the top millimeter of the sediment surface, and growth experiments show that surface sediment supports growth better than detritus falling from the water column.
Abstract: Macoma nasuta Conrad is primarily a deposit-feeding bivalve sucking the top millimeter of the sediment surface. Growth experiments show that surface sediment supports growth better than detritus falling from the water column. Gut clearance time is between 1 and 9 h (12°C). Fecal pellets are ejected in a regular rhythm. However, the total amount of feces per unit time shows considerable individual variation. Due to sorting in the mantle cavity, about 97% (dry weight) of the surface material is ejected again as pseudofeces. Selectivity by the bivalve is estimated by comparison of particle size and organic composition of sandy and muddy sediments and compared with feces produced by clams fed these sediments. Fecal pellets are in all cases richer in organic components than the sediment, indicating a high degree of selectivity. Ingestion and digestion of small animals (meiofauna) occur, but many of the ingested specimens survive. It is not possible to estimate the assimilation of organic matter by simple difference between the ingested sediment and the ejected feces. The difficulties in calculating energy budgets which arise from selective feeding and associated bacteria are discussed.
TL;DR: The ultrastructure of the proximal tubule cells was studied during development of the nephrons in the newborn and adult rat kidney and found that the mitochondria were preferentially located closer to the cell membrane as the tubule developed.
TL;DR: Each presubiculum has an orgainzed terminal pathway to the entorhinal cortices of both hemisphers and a similarly organized projection courses via the dorsal psalterium (dorsal hippocambal commissure) to the contralateral entorhal area.
Abstract: This is a detailed report of a previously described projection from the presubiculum to the entorhinal area (Shipley, '74). The terminal degeneration in the entorhinal area is specifically confined to the outer three layers of this cortex. The projection is topogtaphically organized and confined to dorsal and medial parts of the entorhinal area. A similarly organized projection courses via the dorsal psalterium (dorsal hippocampal commissure) to the contralateral entorhinal area. Thus each presubiculum has an organized terminal pathway to the entorhinal cortices of both hemispheres.
TL;DR: In this article, the authors demonstrate the catalytic regeneration of depolarizers by certain substrates by means of cyclic voltammetry using simple aromatic and aliphatic halides, 1,2-and 1,3-dihalides, carbon dioxide, and activated olefins.
TL;DR: Data indicate that the snail fauna represents a dynamic equilibrium sustained by immigration and extinction, and biotic interrelations may be of main importance in governing the diversity of local faunas.
Abstract: The distribution and diversity of Danish freshwater snails is discussed in the light of MacArthur and Wilson's theory of island biogeography. Species-area curves for 86 eutrophic and oligotrophic ponds and lakes are made and the variance to mean ratios of species numbers in lakes of identical sizes calculated. These data indicate that the snail fauna represents a dynamic equilibrium sustained by immigration and extinction. Different properties of small and large bodies of water are discussed with regard to probability of immigration and extinction. Oligotrophic lakes show a steeper species-area curve than eutrophic ones. This is explained by a higher extinction probability in the former but the total species pool is the same for both types of lakes. The freshwater snails are described as a group largely consisting of fugitive species. Physicochemical factors set the ultimative physiological limits to a species but within the main area of distribution biotic interrelations may be of main importance in governing the diversity of local faunas. These considerations probably have a general application to the hololimnic fauna.
TL;DR: Two induced crossed projections were demonstrated to the subcallosal continuation of fascia dentata, the fasciola cinerea and the crossed medial perforant path, corresponding to their similarity in origin, dendritic localization of termination and Timm stainability to the ordinary, uncrossed medial and lateral perforants which arise in the medial and the lateral parts of the entorhinal cortex, respectively.
Abstract: In the rat the perforant pathways from the entorhinal area normally innervate the fascia dentata only ipsilaterally. However, unilateral ablation of the entorhinal area (deentorhination) induces the formation of an anomalous crossed projection from the intact contralateral entorhinal area to the septal portion of the deafferented fascia dentata. After deentorhination of rats aged from 1–30 days the organization of this projection was analyzed (a) by producing secondary lesions in the intact entorhinal area or perforant paths and observing the resulting anterograde degeneration with Fink-Heimer silver impregnation techniques, and (b) by staining with Timm's sulfide silver method which makes the terminal fields of afferent systems stand out in different tones or colors. Both methods showed the crossed entorhino-dentate projection to consist of two separable components. They were named the crossed medial perforant path and the crossed lateral perforant path, corresponding to their similarity in origin, dendritic localization of termination and Timm stainability to the ordinary, uncrossed medial and lateral perforant pathways (MPP and LPP) which arise in the medial and the lateral parts of the entorhinal cortex, respectively. Similarly induced crossed projections were demonstrated to the subcallosal continuation of fascia dentata, the fasciola cinerea.
The heaviest terminal field of the crossed entorhino-dentate projection which was found in the most rostral and medial parts of the deafferented fascia dentata correlated with a lack of expected aberrant extension into the MPP and LPP terminal zones of commissural and ipsilateral hippocampodentate fibers.
In Fink-Heimer preparations there was little variation in the distribution of the aberrant crossed systems over the range of ages studied although the chronic operations performed earliest postnatally (5 days) tended to produce the heaviest representation. This latter observation appeared consistent with changes in the Timm staining pattern of the deafferented fascia dentata, since with an increase in age at the primary lesion from 5 to 14 days there was an increase in the spread into the fascia dentata of Timm stainable axon terminals from CA3, interpreted as a sign of fewer crossed entorhinal afferents succeeding in a presumable competition with the CA3-derived system for available terminal space. The CA3-derived terminals distributed in an intermediate band in the dentate molecular layer beneath the zones occupied by the crossed entorhinal projections.
The appearance of a similarly placed, but less intense intermediate band of Timm staining on the side contralateral to the chronic lesion was observed. This is tentatively interpreted as an indication that a normal crossed entorhinodentate projection does exist, its removal having caused a spread of Timm stainable terminals from the adjacent CA3. Both careful light microscopic analysis of the degeneration picture which followed acute entorhinal lesions of control animals as well as preliminary electron microscopic studies further indicated the existence of a sparse crossed entorhino-dentate projection in normal rats.
In the rabbit the existence of a normal crossed entorhino-dentate projection has been demonstrated by the authors in an accompanying study. The differences in the morphology of the most septal parts of the fascia dentata and fasciola cinerea of the rat and the rabbit provided an excellent opportunity for evaluation of the role of spatial and temporal factors involved in the regulation of the growth of axons of entorhinal origin.
TL;DR: This investigation focuses on the "reverse" response - when the benthic fish Pleuronectes platessa, which occurs locally under hypoxic conditions, is subjected to higher oxygen tensions.
TL;DR: It is concluded that resource partitioning based on differential utilization of micro-organisms cannot play an important role in the co-existence of Hydrobia ventrosa with other deposit-feeders.
TL;DR: In this article, the authors used the beam-foil technique or the zero-field level-crossing method to determine the radiative lifetimes for excited states in the solar photosphere.
Abstract: Radiative lifetimes for excited states in La ii, Ce ii, Pr ii, Nd ii, Sm ii, Yb i, Yb ii, and Lu ii have been determined by means of the beam-foil technique or the zero-field level-crossing method. The lifetimes for La, Ce, Pr, Nd, Sm, and Yb are shorter than those computed by summing the transition probabilities of Corliss and Bozman by a factor of up to ~5. The large discrepancies between the abundance of La, Ce, Pr, Nd, and Sm in the solar photosphere and in meteorites are eliminated or greatly reduced if the abundance determinations of the solar photosphere are based upon the gf values of Corliss and Bozman, corrected for by the present lifetimes.
TL;DR: The microfauna (protozoa and micrometazoa) and bacteria and microalgae of the sediment of an arctic tundrapond at Barrow, Alaska were quantified through the summer and protozoa were found to be important as bacterial grazers, but they consume only a modest fraction of themicroalgae.
Abstract: The microfauna (protozoa and micrometazoa) and bacteria and microalgae of the sediment of an arctic tundrapond at Barrow, Alaska were quantified through the summer. Very small protozoans (i.e. zooflagellates) and burrowing micrometazoans were found to be the most important components of the microfauna, whereas ciliates play a smaller role. This composition of microfauna is attributed to the mechanical property of the detrital sediment.
TL;DR: This chapter discusses the effect of one hormone on one parameter in one cell type, and a series of isolated muscle preparations have been developed in order to obtain more versatile tools for the study of details in the mechanisms of glucose transport and insulin action.
Abstract: Publisher Summary This chapter discusses the effect of one hormone on one parameter in one cell type. The action of insulin on glucose transport is the classical example of metabolism being controlled by the permeability of membranes and many investigations have been rewarding for promoting understanding of basic patterns in structures, functions, and signals related to transport and hormone action. The effect of insulin on glucose consumption in human peripheral skeletal muscle has also been assessed by measurements of the arteriovenous concentration difference in the forearm. This method has yielded clear-cut evidence that glucose uptake is a function of the insulin concentration in the physiological range, but since it is complicated, it has not been used in many laboratories. Although perfused tissues have several advantages with respect to integrity and insulin sensitivity, they are often heterogeneous and technically difficult to work with. A series of isolated muscle preparations have been developed in order to obtain more versatile tools for the study of details in the mechanisms of glucose transport and insulin action. The small and variable effect of insulin on glucose uptake in smooth muscle cells may have been discouraging for the study of this otherwise important tissue element.
TL;DR: Addition of the organic nucleoside triphosphates, ATP and GTP, both occurring in Tilapia grahami red cells, caused a marked increase inP50 as well asn-values, with GTP having an effect nearly twice that of ATP on oxygen affinity.
Abstract: The oxygen binding properties ofTilapia grahami hemoglobins have been investigated. The whole blood hemolysate possesses at 35°C a high oxygen affinity (P
50∼ 4.0 mmHg). The O2Hb equilibrium is moderately affected by the ionic strenght chloride concentration) of the hemoglobin solution, while in contrast the temperature sensitivity of the O2Hb equilibrium was very high (ΔH=−20.0 kcal.mole−1). Tilapia hemoglobin separated into 7 main fractions having nearly similar Bohr factors (−0.42
TL;DR: In this paper, the authors compared Meyerhof's formula with an atomic two-state expansion and showed that it is an analytical fit to the ab initio results of the authors.
Abstract: We have calculated the projectile and target $K$-excitation cross sections and their ratio for a series of ion-target combinations using a basis of exact molecular eigenstates for a model system of one electron in the field of two effective nuclear charges. Except for very asymmetric high-velocity collisions, close agreement is found with Meyerhof's formula, which is based on an atomic two-state expansion. In this range, Meyerhof's formula may be considered an analytical fit to our ab initio results. We indicate that the apparent accuracy of Meyerhof's formula is due to mutual cancellation of effects arising from approximations and model assumptions used in his deduction of the cross-section ratio. The significant deviation found at high velocities results from interference between the coupling processes that govern $K$-vacancy production. This possibility was ruled out in Meyerhof's theory.
TL;DR: In this article, the authors calculated the shear strain in the Nagssugtoqidian mobile belt and transected an area of intricate interference structures, from which it has been formed by high shear strains.