Showing papers by "University of Alabama at Birmingham published in 1974"

Oxytalan connective tissue fibers: a review.

Abstract: Oxytalan connective tissue fibers are a separate and distinct fiber type. Although current histochemical methods cannot distinguish pre-elastic from oxytalan fibers, the two fiber types are readily distinguished by electron microscopy. Oxytalan fibers are found in periodontal membranes of all teeth of man, monkeys, rats, guinea pigs and mice. Increased numbers and size of oxytalan fibers are observed in periodontal membranes of teeth subjected to increased stress, such as those used for bridge abutments. Edwards (1968) observed increased size and number of oxytalan fibers in periodontal membranes of dog incisors subjected to orthodontic forces. Some oxytalan fibers serve to support the blood and lymphatic vessels leading to the teeth. Oxytalan fibers appear to have a protein component and a stainable component digestible with beta-glucuronidase after peracetic acid digestion. Oxytalan fibers develop in repair tissues of the periodontal membrane. Although oxytalan fibers probably develop in relation to tumors developed from dental tissues, electron microscopy must be employed to distinguish oxytalan from developing elastic tissues inasmuch as histochemical methods are inadequate.

An intraoral model used for studies of fluoride incorporation in enamel

Abstract: . The effect of fluoride on experimental cariogenicity in man was investigated by using bovine enamel surfaces mounted in oral prosthetic appliances. Samples of sound and presoftened enamel were exposed to simulated cariogenic or noncariogenic conditions for 1 week. The samples were periodically immersed in vitro in solutions containing 1 ppm fluoride. For the cariogenic condition, the immersion solution was 3% sucrose, for the noncariogenic condition, water. After the experimental period, the sample enamel was assessed for hardness change and fluoride incorporation. Under the non-cariogenic condition, partial remineralization and high fluoride incorporation were found in the presoftened enamel; both hardness change and fluoride incorporation in sound enamel were minor. The cariogenic condition contributed to higher enamel softening and higher fluoride uptake by both types of samples. The findings suggest a mechanism through which intermittent cariogenesis and remineralization in the presence of fluoride may contribute to increased tooth resistance to caries.

Glucose Intolerance in Infants of Very Low Birth Weight I. Incidence of Hyperglycemia in Infants of Birth Weights 1,100 Grams or Less

Abstract: Forty-three of fifty babies with birth weights 1,100 gm or less were hyperglycemic with serum glucose levels exceeding 125 mg/100 ml while receiving parenteral glucose. Serum glucose levels exceeded 300 mg/100 ml in 36 of these 50 babies. Hyperglycemia was most frequent in the 24 hours after birth and was also related to high rates of glucose infusion (> 0.4 gm/kg/hr from birth) as well as parenteral glucose administration in the absence of oral supplement. These data attest to the fragile nature of glucose metabolism in infants of very low birth weight.

In vitro attachment of streptococci to the tooth surface.

Abstract: The ability of Streptococcus strains to adhere to the tooth surface in vitro was investigated. Polished enamel slabs, with and without acquired pellicles, were incubated with buffer suspensions of oral streptococci, and attached bacteria were counted under a microscope using incident light. Low numbers of bacteria adhered to uncoated enamel; the presence of an acquired pellicle significantly enhanced the attachment of all strains tested. The adherence of Streptococcus sanguis was significantly greater than that of Streptococcus salivarius, and both of these strains adhered in greater numbers than did Streptococcus mutans. When bacteria were suspended in whole saliva, the adherence of S. salivarius and S. mutans was inhibited, whereas the adherence of S. sanguis was enhanced in some experiments and inhibited in others. The adherence of S. sanguis and S. salivarius was consistently inhibited by parotid fluid; this inhibitory effect persisted after thorough washing and resonication of the bacterial cells. Incubation in oral fluids was associated with the attachment of bacterial clumps to the pellicle, and parallel investigation revealed agglutination of S. sanguis and S. salivarius by whole saliva and, in particular, parotid fluid. The results are discussed in terms of surface microecology, and are related to the development of dental plaque.

Inhibition of Phagocytosis-Associated Chemiluminescence by Superoxide Dismutase

Abstract: During the process of phagocytosis, human leukocytes emit a burst of luminescence which can be measured in a liquid scintillation spectrometer. The enzyme superoxide dismutase, which removes superoxide anions (O·), inhibited this chemiluminescence by 70% at a concentration of 100 μg/ml. The enzyme did not inhibit phagocytosis. These results support other studies indicating that O· is elaborated by phagocytizing leukocytes. They also indicate that O· plays a major role in phagocytosis-associated chemiluminescence, though not necessarily as the luminescing agent. Catalase and benzoate inhibited the chemiluminescence of phagocytosis to a slight extent, suggesting that hydrogen peroxide and hydroxyl radical, respectively, might also be involved in this phenomenon. The relationship between the mediators of chemiluminescence and those responsible for phagocytic bactericidal activity remains to be defined.

Modification of B Lymphocyte Differentiation by Anti-Immunoglobulins

Abstract: The discovery that in birds and mammals lymphoid cells mediating delayed sensitivity are developmentally and, in part, functionally independent from those involved in antibody production has greatly stimulated research on the cellular aspects of immunity. Recognition that B and T cells are separate populations has led to the definition of morphologic and functional markers for these cell lines. These markers have made it feasible to study the early events of lymphoid differentiation.

Coronary Perfusion Versus Cold Ischemic Arrest During Aortic Valve Surgery A Randomized Study

Abstract: Sixty-four randomized patients undergoing primary, isolated, scheduled, prosthetic aortic valve replacement were studied to determine the safety of coronary perfusion and mild hypothermia (31 patients) and of cold ischemic arrest (33 patients). Cardiac performance, metabolism, and isoenzyme release and the electrocardiogram were studied early postoperatively. No differences greater than expected by chance were found between the two groups; however, the difference between group means of several hemodynamic variables was significantly larger than experimental error. Combined abnormalities of creatine phosphokinase (CPK) and lactic dehydrogenase (LDH) heart-specific isoenzymes, indicative of myocardial necrosis, were found in 33 of 48 patients (68.7%) so studied. The incidence was similar in both study groups. In 14 of 52 (27%) patients with electrocardiographic studies, changes indicative of new infarction or ischemia were demonstrated, but no differences in incidence between the two groups of patients were...

The origin of monomeric and polymeric forms of IgA in man.

Abstract: A distinctive feature of immunoglobulin A is its tendency to occur in different molecular forms. In contrast to that in most mammalian species, the majority (85 to 90%) of the serum IgA in man occurs in a monomeric form. This prompts a question as to where the monomeric and the polymeric serum IgA is formed and by which cells. Peripheral lymph nodes, spleen, and intestinal lymphoid tissue have long been considered the main sources of circulating IgA (1). However, Hijmans et al. (2) have shown that human bone marrow, because it carries such a large number of cells that contain IgA, can be regarded as a major source of the circulating IgA. Test systems at the cellular level which specifically distinguish between the different molecular forms of IgA may help to clarify this problem.

Transferring Management Theory to Practice

Abstract: The perceptions of researchers and managers are examined with regard to various aspects of the knowledge utilization process, adding an empirical dimension to earlier descriptive efforts. Substanti...

Proteins of the periodontium. Biochemical studies on the collagen and noncollagenous proteins of human gingivae.

Abstract: . Insoluble collagen was prepared from gingivae of full term, stillborn infants (SI) and from that of patients exhibiting gingival hyperplasia that was secondary to diphenylhydantoin therapy (DPH). During the preparations only 4 % of the collagen from DPH was extracted and 17 % from SI gingivae was solubilized, by neutral salt and dilute acid extractants. Subsequent amino acid analysis indicated the presence of a relatively large quantity of the noncollagenous protein(s) in the DPH collagen preparation. After collagen samples were converted to soluble cyanogen bromide (CNBr) pep-tides, the noncollagenous protein(s) proved to be insoluble in the dilute citrate buffer routinely used for initial chromotographic separation of the CNBr peptides. This fraction, whether from DPH or SI gingivae, had essentially the same composition. The noncollagenous protein fraction comprised about 7 and 20 %, respectively, of the dry weights of the SI and DPH insoluble collagen preparations. CNBr peptides from gingival collagen have been purified and shown to be identical with those reported for human skin collagen. Thus, the collagen of gingivae is principally of the type with the chain structure [αl(I)]2α2. Preliminary data strongly suggest the presence in gingivae of a lower level of collagen of the [al (III)]s type.

Site of attachment of J chain to human immunoglobulin M

Abstract: IN spite of a remarkable similarity of the general polypeptide chain structure of immunoglobulins, their molecular weights vary from 150,000 to 950,000 because some occur in monomeric (IgG, IgD and IgE) and others in monomeric or polymeric forms (IgA and IgM) (ref. 1). The largest immunoglobulin, IgM, appears in a stellate configuration of five disulphide-linked subunits (IgM8), each consisting of two pairs of covalently linked heavy (μ) and light (κ or λ) chains2. Recent evidence shows that polymeric immunoglobulins, whether composed of dimers, tetramers or pentamers, contain one molecule of an additional polypeptide, termed J chain3–5. Produced within the same cells as immunoglobulins, J chain becomes attached to polymeric IgM and IgA during the final stages of intracellular assembly6–8. Available results indicate that this polypeptide is essential for polymerisation of monomeric immunoglobulins9,10, has a molecular weight of about 15,000 (refs 11–13), and is covalently attached by disulphide bonds to the Fc region of IgM (refs 14–16). Although the covalent structure of μ chain has been determined17, the exact location of the disulphide bond(s) connecting J chain to μ chain has not been known. To investigate this question, we used available information concerning fragmentation of IgM and of μ and J chains by cleavage with cyanogen bromide (CNBr) (refs 17–20). Because this procedure leaves disulphide bridges intact we reasoned that the portion of μ chain(s) linked by these bridges to J chain would be obtainable as a CNBr fragment.

R6K Plasmid Replication: Influence of Chromosomal Genotype in Minicell-Producing Strains of Escherichia coli K-12

Abstract: Alkaline sucrose velocity sedimentation and cesium chloride-ethidium bromide equilibrium centrifugation have been used to determine the number of copies per chromosomal equivalent of the relaxedly replicating R6K plasmid (a conjugative plasmid conferring ampicillin and streptomycin resistance) in two minicell-producing strains of Escherichia coli K-12. In one strain, the average number of covalently closed circular R6K molecules per chromosomal equivalent is 13 in log-phase and 35 in stationary-phase cells. In the other strain, there is an average of six covalently closed circular R6K molecules per chromosomal equivalent in both log- and stationary-phase cells. Selection from this strain of spontaneously occurring mutants resistant to high concentrations of ampicillin has been accomplished and such mutants show a two- to threefold increase in the number of R6K copies per chromosomal equivalent. Relative to the parental strain, mutants display the following properties: (i) elevated streptomycin resistance, (ii) a 10-fold increase in R6K conjugal transfer, (iii) a 10-fold increase in the amount of R6K plasmid deoxyribonucleic acid segregated into minicells, and (iv) a two- to threefold increase in R6K-specified β-lactamase. The mutation(s) responsible for the increase in the number of R6K molecules per chromosomal equivalent is located on the bacterial chromosome. No R6K-linked mutations conferring the above phenotypes have been obtained. The mutations are presumed to be in chromosomal genes which play a role in the regulation of R6K replication in this strain.

Microelectrode studies of fundic gastric mucosa: cellular coupling and shunt conductance.

Abstract: Necturus fundic gastric mucosa was studied to define the magnitude of cellular and shunt conductance. Electrotonic coupling of surface epithelial cells by a low resistance pathway was shown by analysis of current spread within the epithelial sheet. From this analysis cellular conductance was found to be 4.18 ± 1.57 × 10−4 Ω−1 cm−2, and transepithelial shunt conductance was 1.1 × 10−4 Ω−1 cm−2. The ratio of cell-to-shunt conductance was 3.80. These results are confirmed by a second technique in which the Δp. d. across the serosal membrane of surface cells was compared to the transepithelial Δp. d. resulting from a Δ[K+] in the serosal solution. The data were analyzed using an electrical circuit equivalent to a mucosa composed of two highly coupled cell types. By this technique cell conductance was 3.07 × 10−4 Ω−1 cm−2, and transepithelial shunt conductance was 0.830 × 10−4 Ω−1 cm−2. The cell/shunt conductance ratio was 3.70. Thus, by two independent techniques the transepithelial shunt contributes only 1/5 of the conductance ofNecturus fundic gastric mucosa.

The acquired pellicle: enzyme and antibody activities.

Abstract: — Assays for enzyme and antibody activities have been applied to evaluate functional properties of proteins in 2-h, experimental acquired pellicles. Enzyme activity was demonstrated for human salivary lysozyme and amylase in pellicles grown in vivo as well as in vitro, and antibody activity was demonstrated for rabbit immunoglobulins incorporated in pellicles grown in vitro. Desorption of pellicles prior to functional tests variously affected the activity of the proteins under study, thereby implying differences in the tenacity of protein binding to the pellicles.

Studies on the conformations and interactions of elastin. Proton magnetic resonance of the repeating tetramer

Abstract: Proton magnetic resonance studies at 220 MHz were carried out on synthetic polymers of the repeating tetrapeptide of elastin. Temperature dependence and solvent-mixture dependence of peptide proton chemical shifts were determined for both linear polymers, N-formyl-(Val-Pro-Gly1-Gly2)n-Val OMe where n ≃ 8 and 40, and for cyclic polymers (Val-Pro-Gly1-Gly2)n, where n = 3 and 4. The Gly2 NH was found to be solvent shielded. In addition, by studying the polymers Boc-Val-Pro-Gly1-Gly2-OH, H-Pro-Gly1-Gly2-Val OMe, H(Pro-Gly1-Gly2-Val)3OH, and others, it was demonstrated that the Val C–O immediately preceding the Gly2 NH in the sequence was required for solvent shielding. Also the Gly2 NH resonance is found at higher field than the Gly1 NH resonance. This provides the basis for proposing a β turn in which the Pro and Gly1 residues form the corners, i.e., residues i + 1 and i + 2, and in which the Gly2 NH, residue i + 3 hydrogen bonds to the carbonyl of residue i, the Val residue. Studies on methanol–water solvent systems indicated retention of the β turn as a significant conformational feature. This suggests that the β turn occurs in the elastic fiber, which contains about 60% water but which utilizes association of hydrophobic groups as a primary force in fibrogenesis.

Left Ventricular Size and Function and Heart Size in the Year Following Myocardial Infarction

Abstract: Interrelationships among left ventricular (LV) size, LV function, and heart size were investigated in 49 patients studied 2-12 months after myocardial infarction. LV end-diastolic volume (EDV) and ejection fraction (EF) were determined by biplane ventriculography. Heart size was estimated from chest films by the cardiothoracic ratio (CTR) and cardiac volume (CV) methods. Ventricular function (i.e., EF) was related to chamber size (i.e., EDV), but the correlation coefficient was not high ( r = 0.74); thus, chamber size was not an accurate predictor of EF. Because of the close linear relation that exists between LV end-systolic volume and EDV ( r = 0.98), a hyperbola describes the relation between EF and EDV. In general, EF was depressed ( 2 , was 2 ), and was 150 ml/m 2 . Thus relatively small chamber size ( 2 ) was associated with a wide range in ventricular function, while large chamber size was associated with severe dysfunction (EF 0.50 or CV > 540 ml/m 2 ) was not found consistently until EDV exceeded 150 ml/m 2 . Hence normal heart size was often associated with moderate EF depression (0.49-0.30), while cardiomegaly was often associated with severe dysfunction. Clinical heart failure (CHF) was usually accompanied by EF 2 . Primarily because of this variation in chamber size, both normal heart size and cardiomegaly were at times associated with CHF. The poor correlations of EF with CTR ( r = –0.43) and CV ( r = –0.52) preclude use of the heart size indices as accurate predictors of LV function. When the data were analyzed according to the presence or absence of cardiomegaly, the following generalizations could be made regardless of the heart size method used. Cardiomegaly was a reasonable indicator of postinfarction LV function, being associated with depressed function and often with CHF. However normal heart size was associated with either normal LV function, or commonly, with depressed function, often not clinically apparent.

Hemagglutinins: Primitive Receptor Molecules Operative in Invertebrate Defense Mechanisms *

Abstract: In recent years those of us who hold an interest in comparative immunology have witnessed an increased emphasis in deciphering the molecular events operative in invertebrate defense mechanisms. Our own efforts have centered mainly on the role of various hemolymph factors in invertebrate immunity, and whether these factors bear any relationship to components of vertebrate immune mechanisms. From our studies and those of others, there exists several lines of evidence that: (1) hemagglutinins (HA) represent primitive receptor molecules operative in the immune mechanism of invertebrates, and (2) the hemagglutinins of several key invertebrate species are related chemically. In addition, HA is apparently related to other hemolymph factors such as inducible bactericides, naturally occurring hemolysins, and clotting factors. Thus, in this presentation, we would like to present a unifying concept of how these molecules with seemingly diverse functions may be related, and how they may have evolved from a common ancestral gene. We will also question whether analogies exist between invertebrate hemolymph factors and the immunoglobulins, complement and clotting systems of vertebrates. Admittedly, much will be speculative. However, if one closely peruses the literature, tersely reviewed here, it may be obvious that many of our conclusions have substance.