[Wound management-biology and wound healing disorders]. / Wundmanagement ­ Biologie und Störung der Wundheilung.

Wound healing is one of the most complex biological processes in an organism. It proceeds in three consecutive stages: the exudative, the proliferative, and the reparative phase. For a better understanding of new treatment possibilities, knowledge of the fundamental principles of these phases is required. Depending on the extent, location, bacterial colonization, and stage of a wound, it is important to find the appropriate treatment modality. In the present article, the basic principles of wound healing and disruptive factors are described in preparation for the next part on modern treatment modalities.

Induction of proliferation of basal epidermal keratinocytes by cold atmospheric-pressure plasma.

BACKGROUND: Over the past few decades, new cold plasma sources have been developed that have the great advantage of operating at atmospheric pressure and at temperatures tolerable by biological material. New applications for these have emerged, especially in the field of dermatology. Recently it was demonstrated that cold atmospheric-pressure plasma positively influences healing of chronic wounds. The potential of cold plasma lies in its capacity to reduce bacterial load in the wound while at the same time stimulating skin cells and therefore promoting wound closure. In recent years, there have been great advances in the understanding of the molecular mechanisms triggered by cold plasma involving signalling pathways and gene regulation in cell culture. AIM: To investigate cold plasma-induced effects in ex vivo treated human skin biopsies. METHODS: Human skin tissue was exposed to cold plasma for different lengths of time, and analysed by immunofluorescence with respect to DNA damage, apoptosis, proliferation and differentiation markers. RESULTS: After cold plasma treatment, the epidermal integrity and keratin expression pattern remained unchanged. As expected, the results revealed an increase in apoptotic cells after 3 and 5 min of treatment. Strikingly, an induction of proliferating basal keratinocytes was detected after cold plasma exposure for 1 and 3 min. As these are the cells that regenerate the epidermis, this could indeed be beneficial for wound closure. CONCLUSION: We investigated the effect of cold plasma on human skin by detecting molecules for growth and apoptosis, and found that both processes are dependent on treatment time. Therefore, this approach offers promising results for further applications of cold plasma in clinical dermatology.

Economic evaluation of the effects of planting date and application rate of imidacloprid for management of cereal aphids and barley yellow dwarf in winter wheat.

The effects of planting date and application rate of imidacloprid for control of Schizaphis graminum Rondani, Rhopalosiphum padi L. (Homoptera: Aphididae), and barley yellow dwarf virus (BYDV) in hard red winter wheat were studied. The first experiment was conducted from 1997 to 1999 at two locations and consisted of three planting dates and four rates of imidacloprid-treated seed. The second experiment was conducted from 2001 to 2002 in Stillwater, OK, and consisted of two varieties of hard red winter wheat seed and four rates of imidacloprid. Aphid densities, occurrence of BYDV, yield components, and final grain yield were measured, and yield differences were used to estimate the economic return obtained from using imidacloprid. In the first study, aphid populations responded to insecticide rate in the early and middle plantings, but the response was reduced in the late planting. Yields increased as insecticide rate increased but did not always result in a positive economic return. In the second study, imidacloprid seed treatments reduced aphid numbers and BYD occurrence, protected yield, and resulted in a positive economic return. The presence of aphids and BYDV lowered yield by reducing fertile head density, total kernel weight, and test weight. Whereas the application of imidacloprid seed treatments often provided positive yield protection, it did not did not consistently provide a positive economic return. A positive economic return was consistently obtained if the cereal aphid was carrying and transmitting BYDV and was more likely to occur if wheat was treated with a low rate if imidacloprid and planted in a "dual purpose" planting date window.

Fixed precision sequential sampling plans for the greenbug and bird cherry-oat aphid (Homoptera: Aphididae) in winter wheat.

The numbers of greenbugs, Schizaphis graminum (Rondani), and bird cherry-oat aphids, Rhopalosiphum padi L., per wheat tiller (stem) were estimated in 189 production winter wheat (Triticum aestivum L.) fields located throughout Oklahoma. Taylor's power law regressions were calculated from these data and used to construct fixed precision sequential sampling schemes for each species. An evaluation data set was constructed from 240 samples taken during three growing seasons from winter wheat fields at four locations in Oklahoma. Wheat cultivar and growth stage were recorded for each field on the day of sampling. Taylor's power law parameters for evaluation fields differed significantly for both species among growing seasons, locations, and plant growth stages. Median precision achieved using the fixed precision sequential sampling schemes for each species departed <20% from expected precision over the range population intensity in the evaluation data. For the 10% of samples with greatest deviation between observed and expected precision, observed precision was 13.8-81.8% greater than that expected precision depending on aphid species and population intensity. For the greenbug, the distribution of the percentage deviation between observed and expected precision was positively skewed, so that the sampling scheme tended to over-predict precision. For the bird cherry-oat aphid, the distribution was more symmetric. Even though precision observed using the sampling schemes frequently varied from expected precision, because of the inevitable consequence of sampling error and environmental variation, the sampling schemes yielded median observed precision levels close to expected precision levels over a broad range of population intensity.

Development of a sampling plan in winter wheat that estimates cereal aphid parasitism levels and predicts population suppression.

From 1998 to 2001, the relationship between the proportion of tillers with >0 mummified aphids (Ptm) and the proportion of cereal aphids parasitized (Pp) was estimated on 57 occasions in fields of hard red winter wheat located in central and western Oklahoma. Both original (57 fields) and validation data (34 fields; 2001-2002) revealed weak relationships between Ptm and Pp, however, when Ptm > 0.1, Pp always exceeded the recommended parasitism natural enemy threshold of 0.2. Based on the relationship between Ptm and Pp, upper (Ptm1) and lower (Ptm0) decision threshold proportions were set at 0.1 and 0.02, respectively. We monitored cereal aphid populations in 16-25 winter wheat fields over time, and based on the upper and lower decision threshold proportions (Ptm1 = 0.1, Ptm0 = 0.02), predicted whether aphid intensities (# per tiller) would increase above or be maintained below selected economic thresholds (3, 9, and 15 aphids per tiller). Results of this validation study revealed that aphid intensity exceeded an economic threshold in only one field when predicted to remain below Ptm > 0.1, but aphid intensity reached a maximum of only four aphids per tiller. The sampling plan developed during this study allowed us to quickly classify Ptm, and independent of initial cereal aphid intensities, very accurately predict suppression of populations by parasitoids. Sequential sampling stop lines based on sequential probability ratio tests for classifying proportions were calculated for Ptm1 = 0.1 and Ptm0 = 0.02. A minimum of 26 tiller samples are required to classify Ptm as above 0.1 or below 0.02. Based on the results of this study, we believe that simultaneous use of aphid and parasitoid sampling plans will be efficient and useful tools for consultants and producers in the southern plains and decrease the number of unnecessary insecticide applications.

Effect of greenbugs (Homoptera: Aphididae) on yield loss of winter wheat.

The effect of greenbug, Schizaphis graminum (Rondani), feeding on the yield of four winter wheat cultivars commonly grown in Oklahoma was studied. Cultivars tested were 'Karl', a recent derivative 'Karl-92', and '2163', all greenbug-susceptible cultivars; and 'TAM-110', a cultivar with resistance to biotype E greenbugs. The objectives were to determine the effect of different greenbug densities during fall and spring on yield of winter wheat, and to develop mathematical models to quantify the effect of greenbugs on yield loss. The intensity of greenbug infestations achieved in plots by artificial infestation varied among years and growing seasons within a year, but was generally sufficient to cause a reduction in yield. Among yield components, the number of heads per square meter and the number of seeds per head were frequently negatively correlated with the accumulated number of greenbug-days per tiller. Seed weight was rarely affected by greenbug infestation. A regression model estimated yield loss for greenbug-susceptible cultivars at 0.51 kg/ha loss of yield per greenbug-day in years with near normal precipitation, and a loss of 1.17 kg/ha under severe drought conditions. The susceptible winter wheat cultivars exhibited similar yield loss in relation to the intensity of greenbug infestation, as indicated by a common slope parameter in the regression model. Results suggest that the model is robust for predicting yield loss for susceptible cultivars.

Ultrasonographic examination of injuries to the achilles tendon in dogs and cats.

The value of ultrasonography in the diagnosis of lesions of the Achilles tendon was Investigated in 42 dogs and seven cats. A standardised four-part ultrasonographic examination was established. Linear transducers with a frequency of more than 7.5 MHz were used. Ultrasonography allowed identification and differentiation of total ruptures and the differentiation of partial ruptures into deep or superficial ruptures, or those comprising muscular tears. The healing process could be monitored and imaged using this technique. Suture material was readily visible in surgically treated cases. Displacement of the superficial digital flexor tendon could be identified. In such cases, the tendon tissue was seen either medially or laterally to the calcaneus. The healing process of the Achilles tendon could also be documented using ultrasonography. However, it was not possible to determine the age of the injury and the exact end of the healing process. Ultrasonography therefore proved to be an excellent diagnostic method for imaging lesions of the Achilles tendon and associated injuries in dogs and cats. After physical examination, the technique should be the next logical step in the evaluation of a suspected injury to the Achilles tendon.

Identification of a cis-acting dendritic targeting element in the mRNA encoding the alpha subunit of Ca2+/calmodulin-dependent protein kinase II.

In mammalian neurons a selected group of mRNAs, including the transcript encoding the alpha subunit of Ca2+/calmodulin-dependent protein kinase II, is found in dendrites. The molecular mechanisms underlying extrasomatic RNA trafficking are not well described. It is thought that dendritic transcripts contain cis-acting elements that direct their selective subcellular sorting. Here we report the identification of an extrasomatic targeting element in the 3' untranslated region of the mRNA encoding the alpha subunit of Ca2+/calmodulin-dependent protein kinase II. In primary hippocampal neurons, this 1200-nucleotide-spanning, cis-acting element is sufficient to mediate dendritic localization of chimeric reporter transcripts. The trafficking signal does not share any striking sequence similarity with a previously characterized dendritic targeting element in transcripts encoding the microtubule-associated protein 2. In dendrites of transfected primary neurons, recombinant RNAs form granules with an average diameter of 0.45 microm that may represent preferential RNA docking sites or multimolecular transport units. These findings imply that extrasomatic sorting of individual dendritic mRNAs involves at least partially distinct molecular mechanisms, as well as large trafficking complexes.

Distribution and abundance of insecticide resistant greenbugs (Homoptera: Aphididae) and validation of a bioassay to assess resistance.

Laboratory bioassays were conducted to determine the toxicity of four insecticides (ethyl parathion, chlorpyrifos, malathion, and carbofuran) to insecticide-susceptible and resistant populations of greenbug, Schizaphis graminum (Rondani). These bioassays were used to develop and validate a discriminating concentration for assessing insecticide resistance in greenbug populations in the field. Samples from wheat and sorghum in two states, Oklahoma and Kansas, indicated that insecticide resistance persists in greenbug populations over a large area at a low level.

Two rat brain staufen isoforms differentially bind RNA.

In neurones, a limited number of mRNAs is found in dendrites, including transcripts encoding the microtubule-associated protein 2 (MAP2). Recently, we identified a cis-acting dendritic targeting element (DTE) in MAP2 mRNAs. Here we used the yeast tri-hybrid system to identify potential trans-acting RNA-binding factors of the DTE. A cDNA clone was isolated that encodes a member of a mammalian protein family that is highly homologous to the Drosophila RNA-binding protein Staufen. Mammalian Staufen appears to be expressed in most tissues and brain areas. Two distinct rat brain Staufen isoforms, rStau+I6 and rStau-I6, are encoded by alternatively spliced mRNAs. Both isoforms contain four double-stranded RNA-binding domains (dsRBD). In the larger rStau+I6 isoform, six additional amino acids are inserted in the second dsRBD. Although both isoforms interacted with the MAP2-DTE and various additional RNA fragments in an in vitro north-western assay, rStau-I6 exhibited a stronger signal of bound radioactively labelled RNAs as compared with rStau+I6. Using an antibody directed against mammalian Staufen, the protein was detected in somata and dendrites of neurones of the adult rat hippocampus and cerebral cortex. Ultrastructural studies revealed that in dendrites, rat Staufen accumulates along microtubules. Thus in neurones, rat Staufen may serve to link RNAs to the dendritic microtubular cytoskeleton and may thereby regulate their subcellular localization.

Intramolecular interactions regulate SAP97 binding to GKAP.

Membrane-associated guanylate kinase homologs (MAGUKs) are multidomain proteins found to be central organizers of cellular junctions. In this study, we examined the molecular mechanisms that regulate the interaction of the MAGUK SAP97 with its GUK domain binding partner GKAP (GUK-associated protein). The GKAP-GUK interaction is regulated by a series of intramolecular interactions. Specifically, the association of the Src homology 3 (SH3) domain and sequences situated between the SH3 and GUK domains with the GUK domain was found to interfere with GKAP binding. In contrast, N-terminal sequences that precede the first PDZ domain in SAP97, facilitated GKAP binding via its association with the SH3 domain. Utilizing crystal structure data available for PDZ, SH3 and GUK domains, molecular models of SAP97 were generated. These models revealed that SAP97 can exist in a compact U-shaped conformation in which the N-terminal domain folds back and interacts with the SH3 and GUK domains. These models support the biochemical data and provide new insights into how intramolecular interactions may regulate the association of SAP97 with its binding partners.

Development and validation of a binomial sequential sampling plan for the greenbug (Homoptera: Aphididae) infesting winter wheat in the southern plains.

From 1997 to 1999, Schizaphis graminum (Rondani), intensity (number per tiller) was estimated on 115 occasions from hard red winter wheat fields located throughout the major wheat growing regions of Oklahoma. A total of 32 and 83 fields was sampled during the fall and spring, respectively. The parameters of linear regressions relating the mean number of greenbugs per tiller (m) and the proportion of infested tillers (PT) differed significantly between fall and spring infestations. The PT-m linear model provided a good fit for data on S. graminum for fall and spring infestations at tally thresholds of 0, 1, 2, and 3. A tally threshold (T) represents the number of greenbugs present on a tiller before the tiller is classified as infested by >T greenbugs. A regression model with a tally threshold of 2 was the most precise for classifying S. graminum populations during fall growth of winter wheat because it explained a greater amount of the variation in the PT-m relationship (97%) than models with other tally thresholds. A separate spring model with a tally threshold of 1 was the most precise for classifying S. graminum populations during spring growth of winter wheat. Sequential sampling stop lines based on sequential probability ratio tests were calculated for economic thresholds of 3 or 6 greenbugs per tiller for fall infestations and 6 or 9 greenbugs per tiller for spring infestations. With the newly developed parameters, the average sample number required to classify greenbug populations near economic thresholds (as above or below the economic threshold) varied from 69 to 207. We expect that the sampling plans for greenbugs in winter wheat developed during this study will be efficient and useful tools for consultants and producers in the southern plains.

Two trans-acting rat-brain proteins, MARTA1 and MARTA2, interact specifically with the dendritic targeting element in MAP2 mRNAs.

Different isoforms of the microtubule-associated protein 2 (MAP2) are somatodendritic components of neurons that seem to regulate the stability of the dendritic cytoskeleton. MAP2 localization into dendrites appears to be a complex multicausal mechanism that involves the specific recruitment of MAP2 mRNAs into dendritic compartments. Recently, we have functionally characterized a 640-nucleotide dendritic targeting element (DTE) in the 3' untranslated region (3' UTR) of MAP2 transcripts that mediates extrasomatic mRNA localization in primary neurons (Blichenberg et al. , 1999). In analogy to molecular mechanisms regulating cytoplasmic RNA translocation in other cell systems, we propose that, in vivo, the cis-acting MAP2-DTE interacts with specific protein factors present in neurons. To identify putative trans-acting DTE-binding proteins, we performed in vitro ultraviolet crosslinking assays. Using this experimental system, two 90-kDa and 65-kDa MAP2-RNA trans-acting proteins, MARTA1 and MARTA2, were identified in rat-brain extracts. Both MARTAs bind with high affinity to the MAP2-DTE, but not to other investigated regions of MAP2 transcripts or the somatically restricted alpha-tubulin mRNA. Moreover, MARTA1 and MARTA2 do not bind significantly to other dendritically localized transcripts encoding vasopressin and arg3.1, nor to a dendritic trafficking element from the mRNA encoding the alpha-subunit of the Ca(2+)/calmodulin-dependent protein kinase II. Binding of MARTA1 and MARTA2 to the MAP2-DTE occurs with an affinity in the nanomolar range. Whereas MARTA1 is clearly detectable in crude lysates, cytosolic and ribosomal salt-wash fractions, and in nuclear extracts, MARTA2 is preferentially found in the ribosomal salt-wash preparation. Neither MARTA is restricted to rat brain, and both are present in a number of other rat tissues. Thus, both proteins may be involved in a variety of nuclear and cytoplasmic events that regulate RNA metabolism in different cell types.

Temporal appearance of the presynaptic cytomatrix protein bassoon during synaptogenesis.

Bassoon is a 420-kDa presynaptic cytomatrix protein potentially involved in the structural organization of neurotransmitter release sites. In this study, we have investigated a possible role for Bassoon in synaptogenesis and in defining synaptic vesicle recycling sites. We find that it is expressed at early stages of neuronal differentiation in which it is selectively sorted into axons. As synaptogenesis begins, Bassoon clusters appear along dendritic profiles simultaneously with synaptotagmin I, sites of synaptic vesicle recycling, and the acquisition of functional excitatory and inhibitory synapses. A role for Bassoon in the assembly of excitatory and inhibitory synapses is supported by the colocalization of Bassoon clusters with clusters of GKAP and AMPA receptors as well as GABA(A) receptors. These data indicate that the recruitment of Bassoon is an early step in the formation of synaptic junctions.

Molecular determinants of presynaptic active zones.

The presynaptic cytoskeletal matrix (cytomatrix) assembled at active zones has been implicated in defining neurotransmitter release sites. Munc13, Rim, Bassoon and Piccolo/Aczonin are recently identified presynaptic cytomatrix proteins. These multidomain proteins are thought to organize the exocytotic and endocytotic machinery precisely at active zones.

Piccolo, a presynaptic zinc finger protein structurally related to bassoon.

Piccolo is a novel component of the presynaptic cytoskeletal matrix (PCM) assembled at the active zone of neurotransmitter release. Analysis of its primary structure reveals that Piccolo is a multidomain zinc finger protein structurally related to Bassoon, another PCM protein. Both proteins were found to be shared components of glutamatergic and GABAergic CNS synapses but not of the cholinergic neuromuscular junction. The Piccolo zinc fingers were found to interact with the dual prenylated rab3A and VAMP2/Synaptobrevin II receptor PRA1. We show that PRA1 is a synaptic vesicle-associated protein that is colocalized with Piccolo in nerve terminals of hippocampal primary neurons. These data suggest that Piccolo plays a role in the trafficking of synaptic vesicles (SVs) at the active zone.