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We have found previously that all spontaneous intestinal adenomas from Apc+/ApcMin mice lose the wild type Apc marker on two genetic backgrounds. On the (AKR x B6)F1 background, this event involves loss of the entire homolog of mouse chromosome 18 carrying Apc+. This chromosome carries both the Mcc and Dcc genes, which are homologs of genes that have been implicated in human colorectal cancer. To determine whether the loss of alleles of Mcc and/or Dcc is necessary for the formation of intestinal adenomas, subchromosomal somatic events were induced by gamma-irradiation. The observed spectrum of intrachromosomal somatic genetic losses rules out a requirement for loss of heterozygosity at either locus during adenoma formation. Subchromosomal allelic losses linked to Apc+ occur spontaneously on other genetic backgrounds. In the majority of these events, the Apc+ allele itself was somatically lost, as judged by the wild type marker at the Min site. However, on the [M. musculus castaneous (CAST) x B6-Min]F1 and (129/Sv x B6-Min)F1 backgrounds, spontaneous adenomas were observed in which the wild type marker at the Min site was retained. Further analysis will be required to determine whether these exceptions involve intra-Apc mutations. If not, then these events would illustrate routes to intestinal neoplasia that do not require complete inactivation of wild type Apc function.

Background & Aims: Mutations in the APC gene result in an increased propensity to develop intestinal neoplasia; however, a complete understanding of the mechanisms resulting in tumor formation has remained elusive. Min mice possess a mutation in the APC gene and display a neoplastic phenotype similar to that observed in familial adenomatous polyposis coli in humans. Cyclooxygenase (COX) inhibitors decrease tumor multiplicity in the Min mouse intestine. The present study was designed to determine if there was an increase in COX-2 in adenomas harvested from Min mouse intestine., Methods: COX-2 messenger RNA levels were determined by Northern blots and reverse-transcription polymerase chain reactions of B6Min x 129 mouse-derived tumors. Protein levels and localization were determined by Western blots and immunohistochemical staining., Results: The Northern blots revealed an approximately threefold increase in the level of COX-2 messenger RNA in Min mouse adenoma compared with normal mucosa. COX-2 protein levels in adenomatous tissues were also approximately threefold higher compared with normal mucosa from the same mouse. Immunohistochemical staining with a monospecific COX-2 antibody confirmed that increases in COX-2 immunoreactivity were restricted to dysplastic and neoplastic foci within intestinal mucosa., Conclusions: These data show that COX-2 levels may be increased at an early stage in colorectal neoplasia during polyp formation and before invasion.

About 80% of nosocomial infections are caused by aerobic bacteria. The Pseudomonas aeruginosa is a Gram-negative bacterium pertaining to the Pseudomonadaceae family. P. aeruginosa is responsible for 6-22% of all hospital infections. The aim of this paper is to evaluate the efficacy of both hyperbaric oxygen-therapy (HBO 2 Atm x 35 min/day) alone for 8 days and when associated to the chemoantibiotic therapy (amikacine 15 mg/kg/day for 8 days intraperitoneal), in rats infected through pulmonary and subcutaneous intake. In rats affected by P. aeruginosa, HBO induces a significant reduction in mortality and morbility with bacteria eradication in blood culture findings, bronchial aspirate and skin biopsies. These effects were increased by the use of amikacine which is an antibiotic used for the treatment of Gram-negative bacteria.

Mutation of the APC (adenomatous polyposis coli) gene is an early event in colon tumor development in humans. Mice carrying Min (multiple intestinal neoplasia), a mutant allele of Apc, develop intestinal and mammary tumors as adults. To study the role of the Apc gene in development, we have investigated the phenotype of embryos homozygous for ApcMin (Min). Development of the primitive ectoderm fails prior to gastrulation in homozygous Min embryos. By midgestation, the presumed homozygotes consist of a mass of trophoblast giant cells with an additional cluster of much smaller embryonic cells. These results indicate that functional Apc is required for normal growth of inner cell mass derivatives.

Min (multiple intestinal neoplasia) is a mutant allele of the murine Apc (adenomatous polyposis coli) locus, encoding a nonsense mutation at codon 850. Like humans with germline mutations in APC, Min/+ mice are predisposed to intestinal adenoma formation. The number of adenomas is influenced by modifier loci carried by different inbred strains. One modifier locus, Mom-1 (modifier of Min-1), maps to distal chromosome 4. Intestinal tumours from both B6 (C57BL/6J) and hybrid Min/+ mice show extensive loss of the wild-type allele at Apc. B6 Min/+ female mice are predisposed to spontaneous mammary tumours. The incidence of both intestinal and mammary tumours can be increased in an age-specific manner by treatment with ethylnitrosourea (ENU). Min mice provide a good animal model for studying the role of Apc and interacting genes in the initiation and progression of intestinal and mammary tumorigenesis.

For many years, clinical practice has consolidated the use of both hyperbaric oxygen and oxygen-ozone therapy in the treatment of peripheral occlusive arterial disease (POAD). We investigated the influence of these treatments on hemorrheologic parameters that play an important role in the pathogenesis and the clinical course of arteriosclerosis. Two groups of 15 patients suffering from POAD, assigned at random either to a cycle of HBO therapy or O2-O3 therapy, were evaluated for blood viscosity, erythrocyte filterability, hematocrit value, fibrinogen concentration, and thrombin time. The O2-O3 therapy caused a significant increase of erythrocyte filterability and a significant decrease of blood viscosity. By contrast, HBO therapy did not produce any significant change. The increase of lipid peri-oxidation, proved by raised malonyldialdehyde plasma levels, seems a likely mechanism involved in the hemorrheologic effects of O2-O3 therapy.

Mutation of the APC gene may be a common denominator of all human colon cancer--polypoid and non-polypoid familial cancer as well as sporadic occurrences. Fearon and Vogelstein (1990) have described a series of molecular changes during the progression of human colon cancer, beginning with mutations in APC. Min is a strain of the laboratory mouse carrying a nonsense mutation in Apc, the mouse homologue of APC. The Min strain has been used to test the effect of germline alterations in certain genes identified in the progression pathway of Fearon and Vogelstein. A deficiency in DNA cytosine methylase leads to a reduction in the tumour multiplicity of Min mice contrary to the a priori expectation based on the global hypomethylation of the DNA of early colonic neoplasms. Alterations in Kras had no perceptible effect on the tumour multiplicity of Min mice but may not have been successfully directed to the proliferative cell population. Constitutional mutation of p53 did not influence the multiplicity or histopathology of early Min induced intestinal tumours. The cause and effect analysis of the genetics of colon cancer is clearly in an early phase. An unlinked genetic factor interacting with Min in controlling intestinal tumour multiplicity is Mom1. A central goal for the near future is to identify the Mom1 gene product and to identify other loci that can interact with the Min mutation and affect tumour multiplicity or progression. Mouse chimaeras will permit an analysis of the clonality and cell autonomy of Min induced neoplasms and also of the action of Mom1. The results of these analyses will inform investigators as to what modes of prevention and therapy might be designed for particular tumour types. The Min strain thereby presents an opportunity to discover protective factors against human colon cancer.

Allelic loss at the Apc locus in spontaneously occurring intestinal adenomas from mice heterozygous for the ApcMin nonsense mutation was analyzed using a site-specific quantitative polymerase chain reaction assay. All 97 of the intestinal adenomas analyzed showed extensive loss of the wild-type Apc (Apc+) allele. Quantitative polymerase chain reaction analysis of loci linked to Apc indicated loss of the chromosome carrying Apc+. Only one copy of the homologue carrying ApcMin remained in the intestinal adenomas. Possible reasons for the difference in the mechanism of Apc+ loss between human and Min mouse intestinal adenomas are discussed.

Mutations in the human APC gene caused various familial colon cancer syndromes. The Multiple intestinal neoplasia (Min) mouse provides an excellent model for familial colon cancer: it carries a mutant mouse Apc gene and develops many intestinal adenomas. Here, we analyze how this tumor phenotype is dramatically modified by genetic background. We report the genetic mapping of a locus that strongly modifies tumor number in Min/+ animals. This gene, Mom-1 (Modifier of Min-1), maps to distal chromosome 4 and controls about 50% of genetic variation in tumor number in two intraspecific backcrosses. The mapping is supported by a LOD score exceeding 14. Interestingly, Mom-1 lies in a region of synteny conservation with human chromosome 1p35-36, a region of frequent somatic loss of heterozygosity in a variety of human tumors, including colon tumors. These results provide evidence of a major modifier affecting expression of an inherited cancer syndrome.

The Min (multiple intestinal neoplasia) mutation of the mouse has been mapped by analyzing the inheritance of restriction fragment length polymorphisms and simple sequence length polymorphisms in progeny from two intraspecific crosses segregating for the Min mutation. Min, a mutant allele of Apc, the mouse homolog of the human APC (adenomatous polyposis coli) gene, maps to proximal chromosome 18. The synteny between Apc and Mcc, the mouse homolog of the human MCC (mutated in colorectal cancer) gene, is conserved between mouse and human, although the gene order in the Apc to Mcc interval is different from that in the APC to MCC interval.

Germ-line mutations of the APC gene are responsible for familial adenomatous polyposis (FAP), an autosomal dominantly inherited disease in humans. Patients with FAP develop multiple benign colorectal tumors. Recently, a mouse lineage that exhibits an autosomal dominantly inherited predisposition to multiple intestinal neoplasia (Min) was described. Linkage analysis showed that the murine homolog of the APC gene (mApc) was tightly linked to the Min locus. Sequence comparison of mApc between normal and Min-affected mice identified a nonsense mutation, which cosegregated with the Min phenotype. This mutation is analogous to those found in FAP kindreds and in sporadic colorectal cancers.

Preliminary experience of hyperbaric oxygen (HBO) in the treatment of benign intracranial hypertension (BIH) is reported. Fifty-three patients with BIH were observed. They were treated with antiedema non steroid drugs plus rachicentesis, with steroid drugs plus rachicentesis, with lumbar peritoneal shunt and only 8 with HBO. Each patient underwent HBO with 100% oxygen at 2 atmospheres absolute a day for 15 days. In all patients a gradual disappearance of signs and symptoms of elevated intracranial pressure was observed. No lasting effect of treatment were seen after concluding therapy. The effect of HBO in the treatment of BIH has not yet been clarified, but the results can encourage further experience and studies.

Penetration of membranes by diphtheria toxin in vivo is at least partially triggered by a low pH-induced conformational change occurring within the lumen of an acidic organelle. In order to gain insight into the nature of this change the behavior of the toxin at high pH was characterized and compared to that previously determined at low pH. We find that near pH 10.5 a major conformational change occurs. This change is accompanied by a marked decrease in fluorescence intensity, a red shift in fluorescence emission maximum, and increased susceptibility of protein fluorescence to acrylamide quenching. Differential scanning calorimetry shows that the high pH conformational change involves a cooperative endothermic unfolding transition. These changes at high pH are very similar to those induced by low pH, supporting the conclusion that the changes at low pH also involve a denaturation-like process. In addition, at high pH the toxin gains the ability to bind to model membranes, again similar to its behavior at low pH. On the basis of these studies we conclude that exposure of hydrophobic sequences due to partial unfolding is one dominating component in inducing hydrophobic behavior at both high and low pH, but that at low pH Asp/Glu protonation also contributes to hydrophobicity.

The content of lysine and arginine residues in a number of A-B type protein toxins has been examined. It is found that the A subunit, or its equivalent, often shows a strong bias in the type of basic amino acid residue used tending towards nearly exclusive use of either arginine or lysine rather than use of both, whereas the B subunit or its equivalent shows no such bias. Although arginine codons are GC-rich and lysine codons are AT-rich, the content of GC and AT in the genes coding for the toxins does not adequately explain this bias. Other explanations are discussed, including the possibility that the bias is linked to catalytic function or membrane interaction. Understanding this bias may yield valuable insights into toxin structure and function. Furthermore, identification of bias in sequences may be a useful tool for identifying new toxins and their domains.

Hyperbaric oxygen, useful in treating patients with extensive burns, was used alone in the treatment of three patients with drug-induced toxic epidermal necrolysis. These conditions, although they have different causes, result in a similar biological state of denuded dermis. The therapy was performed in a pressure chamber with pure oxygen at 2 atm for sixty to 120 minutes once a day. Re-epithelialization occurred quickly in all patients and was complete after approximately ten treatments. Our experience, although limited and uncontrolled, points to a beneficial effect of hyperbaric oxygen in the treatment of toxic epidermal necrolysis. Activation of dermal metabolism, enhancement of epidermal regeneration, antishock and antiseptic action, and possibly an immunosuppressive effect are properties of hyperbaric oxygen that may account for its efficacy in the management of toxic epidermal necrolysis.