Unconventional GIY-YIG homing endonuclease encoded in group I introns in closely related strains of the Bacillus cereus group

Several group I introns have been previously found in strains of the Bacillus cereus group at three different insertion sites in the nrdE gene of the essential nrdIEF operon coding for ribonucleotide reductase. Here, we identify an uncharacterized group IA intron in the nrdF gene in 12 strains of the B. cereus group and show that the pre-mRNA is efficiently spliced. The Bacillus thuringiensis ssp. pakistani nrdF intron encodes a homing endonuclease, denoted I-BthII, with an unconventional GIY-(X)₈-YIG motif that cleaves an intronless nrdF gene 7 nt upstream of the intron insertion site, producing 2-nt 3′ extensions. We also found four additional occurrences of two of the previously reported group I introns in the nrdE gene of 25 sequenced B. thuringiensis and one B. cereus strains, and one non-annotated group I intron at a fourth nrdE insertion site in the B. thuringiensis ssp. Al Hakam sequenced genome. Two strains contain introns in both the nrdE and the nrdF genes. Phylogenetic studies of the nrdIEF operon from 39 strains of the B. cereus group suggest several events of horizontal gene transfer for two of the introns found in this operon.

A functional homing endonuclease in the Bacillus anthracis nrdE group I intron

The essential Bacillus anthracis nrdE gene carries a self-splicing group I intron with a putative homing endonuclease belonging to the GIY-YIG family. Here, we show that the nrdE pre-mRNA is spliced and that the homing endonuclease cleaves an intronless nrdE gene 5 nucleotides (nt) upstream of the intron insertion site, producing 2-nt 3' extensions. We also show that the sequence required for efficient cleavage spans at least 4 bp upstream and 31 bp downstream of the cleaved coding strand. The position of the recognition sequence in relation to the cleavage position is as expected for a GIY-YIG homing endonuclease. Interestingly, nrdE genes from several other Bacillaceae were also susceptible to cleavage, with those of Bacillus cereus, Staphylococcus epidermidis (nrdE1), B. anthracis, and Bacillus thuringiensis serovar konkukian being better substrates than those of Bacillus subtilis, Bacillus lichenformis, and S. epidermidis (nrdE2). On the other hand, nrdE genes from Lactococcus lactis, Escherichia coli, Salmonella enterica serovar Typhimurium, and Corynebacterium ammoniagenes were not cleaved. Intervening sequences (IVSs) residing in protein-coding genes are often found in enzymes involved in DNA metabolism, and the ribonucleotide reductase nrdE gene is a frequent target for self-splicing IVSs. A comparison of nrdE genes from seven gram-positive low-G+C bacteria, two bacteriophages, and Nocardia farcinica showed five different insertion sites for self-splicing IVSs within the coding region of the nrdE gene.

[Cost-effectiveness in wound care]

INTRODUCTION

In Germany, treatment costs for pressure ulcer, diabetic foot ulcer and ulcus cruris sum up to Euro 5 billion p. a. (cost of materials only). The question is to be answered how much money could be saved to sick funds, if the treatment is switched from traditional wound care, e. g. hydro-colloids to Vacuum Assisted Closure (V.A.C.).

METHODS

Clinical studies are analysed with regard to complication rates and speed of wound healing V.A.C. vs. traditional. Daily costs and the length of treatment are then correlated and compared.

RESULTS

V.A.C. therapy significantly reduces the time for the wound closing process, hospital admissions and complication rates. Despite higher daily treatment costs (cost of material, only), the V.A.C. therapy turns out to be the superior cost-effective method by far. Assumed V.A.C. therapy substitutes other methods by 50 %, sick funds could have saved Euro 0.7 billion p. a.

DISCUSSION

The V.A.C. related saving potential is not available to sick funds because the approval process for home care use is still (Jan 2006) ongoing since 1999. The improvement of the relevant decision making process is strongly required to faster provide better care and savings at the same time.

SegH and Hef: two novel homing endonucleases whose genes replace the mobC and mobE genes in several T4-related phages

T4 contains two groups of genes with similarity to homing endonucleases, the seg-genes (similarity to endonucleases encoded by group I introns) containing GIY-YIG motifs and the mob-genes (similarity to mobile endonucleases) containing H-N-H motifs. The four seg-genes characterized to date encode homing endonucleases with cleavage sites close to their respective gene loci while none of the mob-genes have been shown to cleave DNA. Of 18 phages screened, only T4 was found to have mobC while mobE genes were found in five additional phages. Interestingly, three phages encoded a seg-like gene (hereby called segH) with a GIY-YIG motif in place of mobC. An additional phage has an unrelated gene called hef (homing endonuclease-like function) in place of the mobE gene. The gene products of both novel genes displayed homing endonuclease activity with cleavage site specificity close to their respective genes. In contrast to intron encoded homing endonucleases, both SegH and Hef can cleave their own DNA as well as DNA from phages without the genes. Both segH and mobE (and most likely hef) can home between phages in mixed infections. We discuss why it might be a selective advantage for phage freestanding homing endonucleases to cleave both HEG-containing and HEG-less genomes.

[Indications and safety aspects of vacuum-assisted wound closure]

Problem wounds continue to challenge medical care. In recent times, good results have been achieved through the application of negative pressure wound therapy. This approach, known as vacuum-assisted wound closure (VAC) involves the use of a defined,controlled negative pressure over a polyurethane or polyvinyl sponge placed in the wound. The wound effluent is evacuated continuously. The result is an improvement of microcirculation, and wound healing is enhanced. Animal experiments have confirmed an increase in cell growth. The basis for surgical wound management continues to be appropriate debridement. In this connection, negative pressure therapy, as a supportive measure, has proved to have major advantages over traditional methods of wound management, advantages that need to be further investigated clinically and experimentally. Consideration of the safety aspects and risk factors associated with the procedure can contribute to the optimization of therapeutic safety.

Traumatization in Survivors of Multiple Aids-Related Loss

This article intends to demonstrate that surviving multiple AIDS-related loss can be traumatizing. Certain characteristics of AIDS as a disease combine with the cumulative impact of multiple loss to heighten traumatic stress in a combined environment of helpless uncertainty and ongoing distress. The focused, community wide impact of AIDS, especially in the gay community, fosters both collective and individual traumatization. Classic symptoms of traumatization arise in survivors of multiple AIDS loss including emotional and social withdrawal and disturbing intrusive recollections. Lifton's conceptualization of the “death imprint” and Seligman's theories of learned helplessness are applied. Implications for treatment and recovery are explored.

Threats to identity in survivors of multiple AIDS-related losses

Survivors of multiple AIDS-related losses face threat to their identity because of the extreme disruption to their personal, assumptive, and interpersonal worlds. This article briefly explains the experience of multiple-loss survivors and includes a case history of a survivor. An individual's sense of self is transformed through identification with the disease. In the gay community, a particularly strong identification with AIDS arose. One outcome of the meshing of an AIDS and homosexual identity is the tendency for gays to assume an identity in relation to HIV ("I am HIV positive/negative.") Personality alteration is not uncommon and may include an inability to trust, labile emotionality, and diffuse anger. Erik Erikson's developmental stage model is used to clarify the confusion survivors face in maintaining and forming identity. Many survivors are catapulted into an integrity versus despair task, reporting many similarities with the situation of their grandparents. The survivor's interpersonal connection to the world, especially their connection to a community, is severely shaken. The article does not ignore the potential for positive identity growth arising from this tragedy. Conclusions from this experience may have applicability in other areas of multiple, ongoing losses.

Issues and implications in the counseling of survivors of multiple AIDS-related loss

Survivors of multiple AIDS-related loss face a unique phenomenon for which existing theories and diagnostic criteria regarding grief and trauma are inadequate. Unresolved grief and complicated bereavement are normal responses to multiple loss. This distinctive experience and the resulting symptoms have implications for counselors. Suggestions are offered for counselors to help clients process the aggregate and individual losses arising from this experience. AIDS provides a rare opportunity to analyze concurrent traumatization and complicated bereavement occurring on an ongoing basis. This analysis and its implications may therefore be useful in the future in regard to tragedies that share these characteristics.

[The structure of drug costs. A criticism of monocausal explanation (author's transl)]

Proceeding from the arguments of a recent publication, an attempt is made to establish whether a monocausal assessment is fruitful in the explanation of the development of drug costs in the statutory health insurance. The question is raised whether the price increase for drugs is in fact the decisive variable determining the costs. This is denied on the grounds of a differential analysis of the causative variables involved and it is shown what role, besides price and quantity components, the innovation or structure effect plays in the development of drug costs.

Human mammary cancers in nu/nu-mice. A model for testing in research and clinic

37 (85%) of 44 human breast cancers are successfully transplanted on thymus-aplastic nu/nu-mice without adjunctive immunotherapy. 16 weeks after transplantation 4 rapidly growing tumours are showing human, female karyotypes. Subsequent investigations proved a good correlation between original tumour and transplant: histology, 3H-thymidine marking index and receptors of androgen and estorgen.

[Observations on tumor-associated fibrinolysis in human breast-cancer (author's transl)]

In 30 cases of breast-cancer, including 24 primary cases, the tumor-associted fibrinolysis was investigated using agar plate method. In 60% of the tissue sample fibrinolytic activity was found. No activity could be detected in the remaining 40%. There was evidence of a positive correlation between tumor-associated fibrinolysis and tumor size as well as the rate of axilla metastases. Among the fibrinolytic active cases there was a disproporionate number of adenocarcinoma, whereas in the inactive collective the solid and scirrhous carcinoma prevailed. There was no relation between the tumor-associated fibrinolysis and the percentage of tumor cells in the tissue. The firbinolytic inactive tumors showed a better histopathological adaptation to the surrounding tissue than the active ones. There was less small-cell infiltrate in the stroma of the fibrinolytic active tumors than in the inactive cases. No significant difference was found in the form of growth and the occurence of fibre structure. For clinical assessment a longer period of observation and a larger study are necessary.

[In-vitro testing of the sensitivity of mammary carcinoma cells to cytostatic drugs (author's transl)]

In-vitro sensitivity to cystostatic agents was tested in 137 cases of breast carcinoma, with 125 tests being analysable. Inhibition of in-vitro incorporation of 3H-uridine or 3H-thymidine into RNA or DNA of the original tumour cells after incubation with antineoplastic substances was used as the index for the in-vivo sensitivity of the tumour. 30% of the carcinoma cells were sensitive in-vitro, 70% resistant. About 75% of sensitive cancers were sensitive against several agents. Cyclophosphamide proved to be most effective in-vitro: it was tested via 4-hydroxycyclophosphamide or 4-hydroperoxycyclophosphamide. There was a correlation between histological type and in-vitro sensitivity of the cancer, as well as between proliferative activity and in-vitro sensitivity in that proliferation-active tumours were more frequently sensitive in-vitro than proliferation-poor ones. Primary tumours and metastases of the same patient frequently showed different sensitivity. In some cases the development of resistance against cytostatic drugs was demonstrated during treatment. Testing tumours against combinations of cytostatic drugs demonstrated an additive effect of the antineoplastic substances in-vitro.