Photoreactivation in the genus Bacillus

Photoreactivation of ultraviolet radiation-induced DNA damage was examined in exponential-phase cells of six mesophilic species of the genus Bacillus. Under the experimental conditions used, it was observed that the laboratory strains B. cereus strain T and B. thuringiensis var. thuringiensis strain NRRL-B4039 exhibited strong photoreactivation (86-fold and 70-fold respectively). Bacillus licheniformis strain ATCC 8480 exhibited moderate (15-fold) photoreactivation. Weak photoreactivation was observed in B. subtilis strain 168 (4-fold) and B. megaterium strain QM B1551 (3.4-fold). Bacillus amyloliquefaciens strain H demonstrated no detectable photoreactivation.     

Dispersal of non-sporeforming anaerobic bacteria from the skin

Dispersal of non-sporeforming anaerobic bacteria was studied. Skin samples were taken from the subjects, and dispersed from different parts of the body was examined. The number of anaerobic bacteria dispersed was not correlated to their density on the surface of skin area exposed. The highest density of anaerobic bacteria on the skin was found in the face and upper trunk, but the highest yield of anaerobic bacteria dispersed came from the lower trunk. The dominant anaerobic bacteria dispersed were Propionibacterium acnes, but Propionibacterium avidum, Propionibacterium granulosum and Gram-positive cocci were also isolated from the dispersal samples. Peptococcus magnus was the most common coccus isolated. For the less frequently isolated bacteria, the best correlation was found between the perineal flora and airborne bacteria. A comparison was also made of bacterial dispersal by naked and dressed subjects. The dispersal of both aerobic and anaerobic bacteria was higher when the subjects were dressed in conventional operating theatre cotton clothing than when they were naked. The increased dispersal of anaerobic bacteria when the subjects were dressed was mainly due to increased dispersal of Propionibacterium sp.     

Photoreactivation of thymine dimers in UV-irradiated human cells: unique dependence on culture conditions

UV-irradiated human fibroblasts in tissue culture were exposed to photoreactivating light in an attempt to demonstrate a light-dependent loss of thymine dimers from the acid-insoluble fraction of the DNA. The only experimental conditions in which this phenomenon was observed was if the cells were grown for at least 10 days in Dulbecco's modified Eagle's minimum essential medium. Such cells lost a maximum of between 10-30% of the thymine dimers from their DNA during illumination for 1 h. When cells were grown in a variety of other media the phenomenon was not observed. The present experiments do not discriminate between true enzymatic photoreactivation and a medium dependent photosensitization phenomenon that is not enzymatic in nature.     

In vitro activity of levofloxacin against a selected group of anaerobic bacteria isolated from skin and soft tissue infections

The in vitro activity of levofloxacin was compared to the activities of ofloxacin, ciprofloxacin, ampicillin-sulbactam (2:1), cefoxitin, and metronidazole for a selected group of anaerobes (n = 175) isolated from skin and soft tissue infections by using the National Committee for Clinical Laboratory Standards-approved Wadsworth method. Ampicillin-sulbactam and cefoxitin inhibited 99% of the strains of this select group, levofloxacin and ofloxacin inhibited 73 and 50%, respectively, at 2 microg/ml, and ciprofloxacin inhibited 51% at 1 microg/ml. The geometric mean MIC of levofloxacin was lower than those of ofloxacin and ciprofloxacin for every group except Veillonella.     

Differential quantitation of surface and subsurface bacteria of normal skin by the combined use of the cotton swab and the scrub methods

By testing adjacent sites on the hypothenar eminence of the palm, enriched with bacteria by massaging the forehead, we found that the numbers of bacteria recovered from the skin surface by a wet cotton swab in 30 s were not significantly different from the numbers obtained by a brisk scrubbing with a blunted Teflon policeman for 120 s. This was true of aerobes (gram-positive cocci) and anaerobes (propionibacteria). If the same site on the palm was swabbed two times for 15 s each time, 67 to 94% of the total recovered bacteria were obtained on the first swab. Differential localization of bacteria into surface and subsurface populations was accomplished by first swabbing a test skin site to assay the surface flora and then scrubbing the same site to test for subsurface organisms. On the palm the swab yielded more aerobes and anaerobes than did the subsequent scrub. On the forehead the scrub yielded three to eight times as many anaerobes as the preceding swab. In some tests gram-positive cocci were distributed on the forehead like propionibacteria (large excess in scrub specimen); in other tests their numbers were similar in the swab and scrub specimens or there was a large excess in the swab specimen. These results indicate that there was no substantial subsurface flora on the palm. On the forehead propionibacteria were predominantly in deeper locations in all tests; gram-positive cocci were variable: in some test sites they were largely at the surface, whereas at other sites a predominance of cocci was in subsurface locations.     

Intracellular bacteria in protozoa

Intracellular bacteria in humans are typically detrimental, and such infections are regarded by the patients as accidental and abnormal. In protozoa it seems obvious that many bacteria have coevolved with their hosts and are well adapted to the intracellular way of life. Manifold interactions between hosts and intracellular bacteria are found, and examples of antibacterial resistance of unknown mechanisms are observed. The wide diversity of intracellular bacteria in protozoa has become particularly obvious since they have begun to be classified by molecular techniques. Some of the bacteria are closely related to pathogens; others are responsible for the production of toxins.     

Hair cycle-dependent plasticity of skin and hair follicle innervation in normal murine skin

The innervation of normal, mature mammalian skin is widely thought to be constant. However, the extensive skin remodeling accompanying the transformation of hair follicles from resting stage through growth and regression back to resting (telogen-anagen-catagen-telogen) may also be associated with alteration of skin innervation. We, therefore, have investigated the innervation of the back skin of adolescent C57BL/6 mice at various stages of the depilation-induced hair cycle. By using antisera against neuronal (protein gene product 9.5 [PGP 9.5], neurofilament 150) and Schwann cell (S-100, myelin basic protein) markers, as well as against neural cell adhesion molecule (NCAM) and growth-associated protein-43 (GAP-43), we found a dramatic increase of single fibers within the dermis and subcutis during early anagen. This was paralleled by an increase in the number of anastomoses between the cutaneous nerve plexuses and by distinct changes in the nerve fiber supply of anagen vs. telogen hair follicles. The follicular isthmus, including the bulge, the seat of epithelial follicle stem cells, was found to be the most densely innervated skin area. Here, a defined subpopulation of nerve fibers increased in number during anagen and declined during catagen, accompanied by dynamic alterations in the expression of NCAM and GAP-43. Thus, our study provides evidence for a surprising degree of plasticity of murine skin innervation. Because hair cycle-associated tissue remodeling evidently is associated with tightly regulated sprouting and regression of nerve fibers, hair cycle-dependent alterations in murine skin and hair follicle innervation offer an intriguing model for studying the controlled rearrangement of neuronal networks in peripheral tissues under physiological conditions.     

Mechanisms of palmar skin resistance and skin potential.

Attempts to analyze peripheral and central factors responsible for 4 electrical properties of palmar skin: (1) skin-resistance level (SRL), (2) skin-resistance responses (SRRs), (3) skin-potential level (SPL), and (4) skin-potential responses (SPRs), the latter being often diphasic—an initial negative change in potential followed by a positive wave. SRL and SRRs are closely linked with sweat-gland activity, with a possible contribution from epidermal factors. Available data suggest that SPL is largely independent of sweat-gland activity and may relate to certain membrane characteristics of the epidermis. In SPR, the latency of the negative wave seems to correlate closely with the latency of the SRR; both are probably functions of the presecretory activity of sweat glands. The mechanism of the positive wave is in doubt; it is regarded by some as a secondary aspect of sweat-gland activity and by others as being of independent epidermal origin. (2 p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuropeptides in the skin: interactions between the neuroendocrine and the skin immune systems

The interaction between components of the nervous system and multiple target cells in the cutaneous immune system has been receiving increasing attention. It has been observed that certain skin diseases such as psoriasis and atopic dermatitis have a neurogenic component. Neuropeptides released by sensory nerves that innervate the skin and often contact epidermal and dermal cells can directly modulate functions of keratinocytes, Langerhans cells (LC), mast cells, dermal microvascular endothelial cells and infiltrating immune cells. Among these neuropeptides the tachykinins substance P (SP) and neurokinin A (NKA), calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and somatostatin (SOM) have been reported to effectively modulate skin and immune cell functions such as cell proliferation, cytokine production or antigen presentation under physiological or pathophysiological conditions. Expression and regulation of their corresponding receptors that are expressed on a variety of skin cells as well as the presence of neuropeptide-specific peptidases such as neutral endopeptidase (NEP) or angiotensin-converting enzyme (ACE) determine the final biological response mediated by these peptides on the target cell or tissue. Likewise, skin cells like keratinocytes or fibroblasts are a source for neurotrophins such as nerve growth factor that are required not only for survival and regeneration of sensory neurons but also to control responsiveness of these neurons to external stimuli. Therefore, neuropeptides, neuropeptide receptors, neuropeptide-degrading enzymes and neurotrophins participate in a complex, interdependent network of mediators that modulate skin inflammation, wound healing and the skin immune system. This review will focus on recent studies demonstrating the role of tachykinins, CGRP, SOM and VIP and their receptors and neuropeptide-degrading enzymes in mediating neurogenic inflammation in the skin.     

Repression of catabolites in gram-positive and gram-negative bacteria

Analyzes the mechanism of catabolite repression of grampositive and gramnegative bacteria. The role of cyclic adenosine monophosphate and CRP protein, forming a complex, is shown. Contribution of ATP kinase to manifestation of the catabolic repression phenomenon in grampositive bacteria is discussed.     

Disaccharide analysis of human skin glycosaminoglycans in sun-exposed and sun-protected skin of aged people

The negative conduction effect of quinidine on each of the successive phases of the ventricular depolarization was investigated using an original noninvasive method: the spatial velocity electrocardiogram of the QRS complex (SVECG-QRS). We performed a randomized placebo-controlled trial in 10 healthy subjects with a single oral dose of quinidine (330 mg) or placebo. Electrocardiographic acquisition and processing (220 recordings for the complete trial) were performed using the Lyon vectorcardiographic program. For each SVECG-QRS curve, the position of seven specific points from A (onset of QRS) to G (end of QRS) were determined precisely. The six successive time intervals between these points (AB-FG) and five velocity values (B-F) were then calculated. The QRS complex was longer under quinidine than placebo (102.4 +/- 1.6 vs. 100.3 +/- 1.5 ms). The difference was at the periphery of statistical significance (p = 0.05), and this lack of statistical difference may be mainly due to the low serum levels of quinidine obtained at the peak of the concentration (1.46 +/- 0.4 mg/1). All six QRS time intervals were longer under quinidine, but only the BC interval was significantly different (9.3 +/- 1.1 vs. 18.8 +/- 1.1 ms; p < 0.05) suggesting a more pronounced negative conduction effect at the onset of ventricular depolarization. No significant modifications were observed for the velocity values. We conclude that (1) the negative conduction effect of quinidine is heterogeneous, but a further study with a higher dose of quinidine (concentration-dependent effect) is required to confirm this hypothesis and (2) the spatial velocity electrocardiogram of the QRS complex allows a detailed analysis of the ventricular conduction phases. The results of the measurement were found to be reproducible. This noninvasive tool could be used in clinical practice to assess effects of antiarrhythmic drugs on successive ventricular depolarization phases.     

Obligately anaerobic bacteria in biotechnology

New obligately anaerobic bacteria are being discovered at an accelerating rate and it is becoming very evident that the diversity of anoxic biotransformations has been greatly underestimated. Furthermore, among contemporary anaerobes there are many that thrive in extreme environments including, for example, an impressive array of both archaebacterial and eubacterial hyperthermophiles. Free energy for growth and reproduction may be conserved not only via fermentations but also by anoxygenic photophosphorylation and other modes of creating transmembrane proton potential. Thus forms of anaerobic respiration in which various inorganic oxidants (or indeed carbon dioxide) serve as terminal electron acceptors have greatly extended the natural habitats in which such organisms may predominate. Anaerobic bacteria are, however, often found in nature as members of close microbial communities (consortia) that, although sustained by syntrophic and other relations between component species, are liable to alter their composition and character in response to environmental changes, e.g., availability of terminal oxidants. It follows that the biotechnological exploitation of obligately anaerobic bacteria must be informed by knowledge both of their biochemical capacities and of their normal environmental roles. It is against this background that illustrative examples of the activities of anaerobic bacteria are considered under three heads: 1. Biodegradation/Bioremediation, with special reference to the anaerobic breakdown of aromatic and/or halogenated organic substances; 2. Biosynthesis/Bioproduction, encompassing normal and modified fermentations; and 3. Biotransformations, accomplished by whole or semipermeabilized organisms or by enzymes derived therefrom, with particular interest attaching to the production of chiral compounds by a number of procedures, including electromicrobial reduction.     

Structure and distribution of pentapeptide repeats in bacteria

We report the discovery of a novel family of proteins, each member contains tandem pentapeptide (five residue) repeats, described by the motif A(D/N)LXX. Members of this family are both membrane bound and cytoplasmic. The function of these repeats is uncertain, but they may have a targeting or structural function rather than enzymatic activity. This family is most common in cyanobacteria, suggesting a function related to cyanobacterial-specific metabolism. Although no experimental information is available for the structure of this family, it is predicted that the tandem pentapeptide repeats will form a right-handed beta-helical structure. A structural model of the pentapeptide repeats is presented.     

Intracytoplasmic bacteria in Onchocerca volvulus

Ultrastructural studies on Onchocerca volvulus disclosed intracellular organisms within the lateral chords of adult worms and of the larval stages. In the females the organisms were also present in the oogonia, oocytes, developing eggs and microfilariae. The organisms, found within vesicles of host (filarid) membrane and limited to the cytoplasm of infected cells, appeared to have a developmental cycle consisting of three morphologically distinct forms: a small spheroidal form up to 0.3 micronm in size, a bacillary form up to 1.5 micron7 in length and 0.7 micronm in diameter, and a third form, intermediate in size between the former and the latter, characterized by a dense inclusion. The intravesicular location and the developmental cycle consisting of three distinct forms are the two characteristics which suggest that these organisms are more similar to the chlamydiae than to the rickettsiae, in spite of their being transovarially transmitted. The significance of these findings with respect to the host-parasite relationship and pathogenesis of onchocerciasis is presently unknown and will require further study.     

Luminal bacteria and small-intestinal permeability

BACKGROUND: The influence of luminal bacteria on small-intestinal permeability has not been fully assessed. This study addressed this issue. METHODS: Thirty-four subjects (mean age 64 years; range 22-95 years) were investigated for possible small-intestinal bacterial overgrowth (SIBO) with culture of a small-intestinal aspirate. A lactulose/mannitol small-intestinal permeability test was performed, small-intestinal histology assessed and serum vitamin B12 concentrations measured in all subjects. Permeability was also assessed in a control group of 34 asymptomatic volunteers. RESULTS: Urinary lactulose/mannitol ratios were significantly increased in subjects with SIBO with colonic-type flora (P < 0.0005), even in the absence of villous atrophy. Urinary lactulose/mannitol ratios were increased in this group due to significantly increased urinary lactulose concentrations (P < 0.0005) rather than reduced urinary mannitol levels, after correcting for inter-subject variations in renal function. Counts of intraepithelial lymphocytes of CD8 phenotype were significantly increased in this group (P = 0.003). Although a significant correlation was found between intraepithelial lymphocyte counts and small-intestinal permeability overall (P < 0.002), these counts were not significantly different in subjects with SIBO with colonic-type flora whose permeability values were < or = > 0.028, the upper limit of normal in asymptomatic controls. Serum vitamin B12 concentrations did not differ significantly between groups (P > 0.5). Ageing did not independently influence small-intestinal permeability (P > 0.5). CONCLUSIONS: Small-intestinal permeability is increased in subjects with SIBO with colonic-type bacteria. This effect is independent of ageing and not mediated by vitamin B12 deficiency. Although counts of intraepithelial lymphocytes of CD8 phenotype are increased in this disorder, it is also unlikely that these cells play an important causative role in this process. Routine light microscopic assessment underestimates the prevalence of small-intestinal functional disturbance in this disorder.     

Site-specific codon bias in bacteria

Sequences of the gapA and ompA genes from 10 genera of enterobacteria have been analyzed. There is strong bias in codon usage, but different synonymous codons are preferred at different sites in the same gene. Site-specific preference for unfavored codons is not confined to the first 100 codons and is usually manifest between two codons utilizing the same tRNA. Statistical analyses, based on conclusions reached in an accompanying paper, show that the use of an unfavored codon at a given site in different genera is not due to common descent and must therefore be caused either by sequence-specific mutation or sequence-specific selection. Reasons are given for thinking that sequence-specific mutation cannot be responsible. We are unable to explain the preference between synonymous codons ending in C or T, but synonymous choice between A and G at third sites is largely explained by avoidance of AG-G (where the hyphen indicates the boundary between codons). We also observed that the preferred codon for proline in Enterobacter cloacea has changed from CCG to CCA.     

Matrix metalloproteinases in skin

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases collectively capable of degrading essentially all extracellular matrix components. These enzymes can be produced by several different types of cells in skin such as fibroblasts, keratinocytes, macrophages, endothelial cells, mast cells, and eosinophils and their activity can be specifically inhibited by TIMPs (tissue inhibitors of metalloproteinases), which bind to active MMPs with 1:1 stoichiometry. In general, MMPs are not constitutively expressed in skin but are induced temporarily in response to exogenous signals such as various cytokines, growth factors, cell matrix interactions and altered cell-cell contacts. At present, more evidence is accumulating that MMPs play an important role in proteolytic remodeling of extracellular matrix in various physiologic situations, including developmental tissue morphogenesis, tissue repair, and angiogenesis. On the other hand, MMPs play an important pathogenetic role in excessive breakdown of connective tissue components, e.g. in rheumatoid arthritis, osteoarthritis, chronic ulcers, dermal photoageing, and periodontitis, as well as in tumor cell invasion and metastasis. In this review we discuss the role of MMPs and TIMPs in human skin based on new observations on the regulation of the expression of MMPs, on their substrate specificity, and MMP expression in physiologic and pathologic conditions of skin involving matrix remodeling. Furthermore, therapeutic modalities based on regulating MMP activity will be reviewed.     

Esthetics and the skin

The possible role of cyclic nucleotide-dependent protein kinases in mediating the stimulatory actions of Fundulus heteroclitus pituitary extract (FPE) during ovarian steroidogenesis and oocyte maturation in vitro was investigated. Follicle-enclosed oocytes were cultured in the presence of FPE and/or N-[2-Methylamino)ethyl]-5-isoquinolinesulfonamide (H-8), a compound that inhibits protein kinase A (PKA) and cGMP-dependent protein kinase. H-8 alone (0.1-1 mM) promoted oocyte germinal vesicle breakdown (GVBD) in a dose-dependent manner. However, the process of GVBD initiated by H-8 was much slower that that triggered by 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17,20 betaP), the natural inducer of oocyte maturation in F. heteroclitus. Treatment with H-8 also increased 17,20 betaP production by the follicles and the accumulation of this steroid in the media was much slower than that initiated by FPE. However, in contrast to the FPE action on the oocyte, which is mediated by 17,20 betaP, the stimulatory action of H-8 on GVBD appears to be independent of follicular steroid production, since aminoglutethimide (AGI), an inhibitor of steroidogenesis, did not-block H-8-induced GVBD while inhibiting H-8 induced 17, 20 betaP production. Moreover, addition of H-8 to FPE-treated follicles significantly reduced 17,20 betaP secretion and the percentage of GVBD. These results provide further support for the involvement of PKA in the mechanism by which FPE stimulates ovarian steroidogenesis in F. heteroclitus. Furthermore, the fact that H-8 alone increased 17,20 betaP levels may imply that basal follicular production of this steroid could be induced by inactivation of cyclic nucleotide-dependent protein kinases. Data also indicate that inhibition of PKA and/or c-GMP-dependent protein kinase in the oocyte may be involved in the mechanism leading to resumption of meiosis in this species.