Loss Of Wall Research Articles

ROLE OF PROTOPLASTS IN PATHOGENESIS OF PYELONEPHRITIS.

The present experiments were designed to study the host-parasite-drug relationship in infection. Protoplasts are a form of bacteria characterized by loss of cell wall and consequent increased osmotic fragility. Because of this, protoplasts are not readily cultured on standard bacteriological media unless precautions are taken to osmotically stabilize the media. Protoplasts were isolated from renal tissue, following apparent cure of experimental pyelonephritis. Ureteral ligation, dehydration, or mannitol-induced diuresis did not cause exacerbation of protoplast infection. Erythromycin, an inhibitor of protein synthesis, while ineffective against the bacterial form of infection was successful in killing protoplasts in vivo.

CEPHALOPOD PHYLOGENY AND CLASSIFICATION

Summary1. A mode of origin of cephalopod buoyancy, by withdrawal of the animal from the apex of the shell followed by withdrawal of liquid from the resulting space, is suggested.2. Buoyancy, once evolved, gave cephalopods an immediate advantage over contemporary animals and evolutionary radiation in the early Ordovician was a consequence of this.3. The earliest cephalopods probably had curved (cyrtocone) shells. Tightly coiled shells evolved from cyrtocones in at least two separate lineages and were in the first place adapted to a benthonic existence. Straight shells (orthocones) were adapted for efficient swimming. They usually had apical counterweights to maintain a horizontal position, but in forms without counterweights, liquid‐filled chambers could have served the same purpose.4. Six evolutionary branches are described, which were distinct by the end of the Canadian (Lower Ordovician). Each branch is believed to be monophyletic, and up to a point each is characterized by certain structures or trends.5. Increased efficiency in jet propulsion became possible in one orthocone group, consequent on loss of the ventral wall of the body‐chamber, so that the mantle cavity wall could become muscular and contractile. This group gave rise to the living di‐branchiates, or Coleoidea.6. The primitive septum, which was concave forwards, remained standard in most orthocones and in some coiled shells. Folded septal edges, giving rise to more or less complex septal sutures, evolved independently in a number of coiled lineages. Their significance is unknown.7. The siphuncle is simple and small in all coiled shells and in some orthocones. In some cyrtocones and other orthocones large siphuncles of complex structure were evolved. They usually contain deposits which are interpreted as counterweights.8. Existing classifications of cephalopoda stem from subdivisions recognized in the nineteenth century when knowledge of fossils was inadequate. They are ill‐balanced and should be abandoned.9. A classification based on phylogeny is now possible. The six branches already described may be regarded as major subdivisions. In addition, it may be desirable to subdivide branches on the basis of important evolutionary changes. The strongest case is for the separation of Coleoidea on the grounds of the loss of the shell.

On growth and nutritional comparisons of a group A streptococcus before and after cell wall removal

Major differences in the vitamin requirements were not detected upon conversion of a coccus to a stable L form, i.e., permanent loss of cell wall. A purified protein has been found that successfully replaces the heterogeneous and more complex horse serum hitherto required as a necessary ingredient for growth of the coccal L form. A medium of low vitamin and low lipid content has been compounded that may prove useful for further nutritional as well as lipid studies of reproducing coccal L forms lacking a cell wall.

STREPTOCOCCAL L FORMS V

Edwards, John (University of Illinois College of Medicine, Chicago, and Albert Einstein Medical Center, Philadelphia, Pa.) and Charles Panos. Streptococcal L-forms. V. Acid-soluble nucleotides of a group A Streptococcus and derived L form. J. Bacteriol. 84:1202-1208. 1962.-This report deals with a comparison of the acid-soluble nucleotides from a group A, type 12, beta-hemolytic streptococcus and a derived stable L form. This is the first report of the presence of a cell-wall precursor (uridine diphosphate-muramic acid-peptide) in a stable L form. Cells of each organism were obtained during their logarithmic phases of growth, harvested by centrifugation, and washed with osmotically protective NaCl solutions. The analytical procedures were essentially those of Franzen and Binkley. Calculated values indicated that these results could not be accounted for by dry-weight differences due to loss of the streptococcal cell wall. It was found that both organisms contained the same amount of total nucleotide material. The L form contained no uridine monophosphate (UMP), a large concentration of uridine diphosphate (UDP)-muramic acid-peptide, and a significant increase of UDP-N-acetylglucosamine. A similar nucleotide containing muramic acid-peptide was not demonstrable in the parent coccus. Instead, UMP and an unidentified uridine nucleotide were resolved in this region. Analyses of extracts from this streptococcal L form indicate the probable presence of two of the three nucleotides originally isolated by Park from penicillin-treated Staphylococcus aureus. The presence of the UDP-muramic acid-peptide cell-wall precursor in the L form cultured in the continual absence of penicillin points to an inability of this form to resynthesize the rigid cell wall and indicates that this synthetic mechanism has been permanently impaired.

STREPTOCOCCAL L-FORMS IV

Panos, Charles (University of Illinois College of Medicine, Chicago, and Albert Einstein Medical Center, Philadelphia, Pa.). Streptococcal L-forms. IV. Comparison of the metabolic rates of a Streptococcus and derived L-form. J. Bacteriol. 84:921-928. 1962.-Glycolytic rates of hexoses, amino sugars, pentoses, two-carbon compounds, and certain intermediates of glycolysis and the adaptive response to glucose of a group A Streptococcus and its derived L-form were compared. It was found that removal of the streptococcal cell wall did not result in the loss of the homolactic characteristic of the parent coccus or in a marked increase in the metabolism of certain glycolytic intermediates by the L-form. It was shown that (i) a major difference exists between the coccus and its L-form in the metabolism of glucosamine and N-acetylglucosamine; (ii) apparently, a loss of selectivity and internal control occurred in the transformation to the L-form; and (iii) this form, unlike the parent coccus, displayed an adaptive response to glucose. These data were not the result of an internal loss of essential cofactors or enzymes by diffusion from within the L-form. Nor could they be accounted for by dry-weight differences due to loss of the streptococcal cell wall. Finally, it was observed that the sonically disintegrated L-form in 0.5 m NaCl was capable of a glycolytic activity of 46% of that of the total intact culture. These data suggest that the conversion of a streptococcus to the L-form is accompanied by an alteration in carbohydrate metabolism as well as the loss of the cell wall. Previously reported data are in agreement with these findings and support the conclusion that the resulting form is not merely a bacterial cell without a rigid cell wall.

On the Shielding of Noise Outdoors

Shielding of noise by buildings and walls can serve very usefully in the control of noise in communities. Fehr has reported a method, derived from diffraction theory, for computing the insertion loss of an impervious wall of infinite length and arbitrary height, placed between a point source and point receiver at arbitrary distances from the wall. Hayhurst has reported measurements on shielding by walls up to forty feet high, using stationary aircraft as noise sources. This paper presents further measurements on shielding by structures outdoors and attempts to correlate the available results with theory. In practice one must take into account, in addition to the idealized diffraction from an infinite shield, several factors including (a) finite size and detailed geometry of the shielding structure; (b) radiation from the ground image of the noise source; (c) attenuation contributed by the terrain, with and without the shield interposed; (d) refraction, scattering, and shadow effects caused by wind and temperature gradients and by turbulence. Studies of these effects have been made and procedures for estimating the amount of shielding obtainable in certain practical cases will be reported.

Transmission of Reverberant Sound through Double Walls

The transmission of reverberant sound through a double wall, which consists of two identical single walls coupled by an airspace, is investigated both theoretically and experimentally. A theory is developed which gives good agreement with experiment. In order to compute the transmission loss of a double wall, it is necessary to know the impedance Zw of the single wall. Zw was determined from experiments conducted on the single wall and includes the effects of mass, dissipation, and flexural motion. The treatment shows that it is impossible to get a large improvement in transmission loss for a double wall relative to a single wall under reverberant sound field conditions if the single wall is considered to have only mass reactance. In addition, the customary normal incidence theory is totally inadequate in explaining the behavior of a double wall in a reverberant sound field. For double walls having air-coupling only, very shallow airspaces can produce appreciable increases in transmission loss over a single wall. An absorbent material when inserted in the airspace produces large improvements only when the mass of the walls is relatively light and has but little effect for heavy walls. Honeycomb or other non-absorbent cellular structures having no cell walls in a direction normal to the wall faces do not result in an increase in transmission loss. Air-coupled walls having no solid sound conducting paths between individual septa are extremely effective sound insulators as compared to conventional double wall constructions. The theory indicates that a large improvement in the transmission loss of a double wall can be obtained by using as components single walls with high internal dissipation.

MOTILITY OF THE STOMACH AFTER LOCAL RESECTION FOR GASTRIC ULCER

Gastric ulcer is very frequently treated by local excision with or without gastro-enterostomy. Excision may be accomplished by knife or cautery; the result in either case is dependent on the loss of stomach wall. The present study is not an appeal to economize gastric wall in removing ulcer, but an inquiry into the resulting functional capacity of the stomach after adequate stomach wall with the ulcer has been excised. The pylorectomies and partial gastrectomies are not considered. Gastrectomies are to be discussed in which the segments removed from the stomach are sometimes described as triangular, saddle-shaped, annular, or irregularly circumcized sections. It is conceivable that the removal of such pieces of stomach wall may affect the gastric motility in different ways, and that with some excisions gastro-enterostomy may be indicated and with others it may not. In an ulcerated stomach, the motility is understood to be normal or increased in

The pathology of foot-and-mouth disease

The equine hoof capsule protects the softer, more sensitive, structures within. Failure of the connection between hoof and bone (the lamellar, distal phalangeal attachment apparatus) results in the crippling lameness of laminitis. Dozens of different keratin molecules, with differing biomechanical properties and molecular weights, with varying degrees of hardness and sulfur concentration, are expressed in hoof tissue. Nonstop production of new hoof makes good the continual loss of hoof wall, occurring at the distal ground surface. A new calculation of the proliferative index (PI), for basal cells of the coronet and lamellae of the dorsal hoof wall, shows that active basal cell proliferation occurs only in the coronet and proximal lamellae. The remaining lamellae are virtually nonproliferative and remodeling within the hoof wall lamellae, that must occur as the hoof wall moves past the stationary distal phalanx, is a function of the controlled activation and inhibition of matrix metalloproteinases (MMPs). Proliferating coronet basal cells organize into thin, elongated cylinders (hoof wall tubules) approximately 0.2 mm in diameter. The central hollow medulla of each tubule comprises about 2% of the total hoof wall volume at the toe. The tubules of the stratum medium are arranged into zones based on the density of tubules in the intertubular horn. This tubule density gradient appears to be a mechanism for smooth energy transfer, from the rigid (high tubule density) outer wall to the more plastic (low tubule density) inner wall, and ultimately to the distal phalanx. The gradient in tubule density mirrors the gradient in water content across the hoof wall and together these factors represent an optimum design for equine hoof wall. The lamellar corium derives most of its blood supply from the branches of the terminal arch which perforates the distal phalanx. Numerous anastomoses form an arterial lattice beneath and between the epidermal lamellae and blood can flow proximally to the coronary circumflex artery and distally to the solar circumflex artery. Veins within the foot are valveless and this can be exploited clinically for retrograde venous therapy or contrast radiography (venograms). In the lamellar dermal microcirculation numerous (500/cm2) arteriovenous anastomoses connect the axial arteries to axial veins; their normal role relates to thermoregulation and pressure modulation. On the inner hoof wall (stratum internum) is the stratum lamellatum (layer of leaves) is named after the 550 to 600 epidermal lamellae (primary epidermal lamellae or PEL) which project from the surface of the inner hoof wall (stratum internum) in parallel rows. Each PEL has 150 to 200 secondary lamellae on its surface and normal SELs have a constant histological appearance that only laminitis alters. The basement membrane (BM), a tough, unbroken sheet of extracellular matrix, forms the interface between the lamellar epidermis and the dermis. It is a three-dimensional sheet of fine, anastomosing cords consisting of filaments of collagen IV ensheathed with glycoproteins, in particular laminins 1 and 5. The plasma membrane of each lamellar basal cell is attached to the BM by numerous electron dense adhesion plaques or hemidesmosomes (HDs). The various proteins of each HD occur on both sides of the basal cell plasmalemma and with anchoring filaments (AFs) form a bridge linking the interior of the basal cell to the exterior connective tissue and ultimately the distal phalanx. Importantly, HDs are maintained and assembled by glucose-consuming phosphorylation reactions and perturbations of glucose metabolism may be involved in laminitis pathogenesis. HDs and AFs are essential to normal hoof lamellar integrity and this is illustrated by horses that inherit mutations in the genes expressing these proteins. Failure to correctly express plectin or laminin5 (HD and AF proteins, respectively) results in neonatal, laminitis-like pathology. Laminitis destroys the BM and its components and without an intact, functional, basement membrane, the structure and function of the lamellar epidermis is pathologically compromised. Transcription and activation of MMP-2 occurs in normal hoof lamellae and in increased amounts during laminitis. Accidental triggering of uncontrolled, excessive MMP production of MMPs, present in the cells of the secondary epidermal lamellae, presumably for normal remodeling purposes, appears to be an important player in laminitis pathogenesis.