Predictors and outcomes of disseminated tuberculosis in an intermediate burden setting.

SETTING: University-affiliated hospital located in Porto, North Portugal, an area with a low to intermediate incidence of tuberculosis (TB). OBJECTIVE: To identify predictors and outcomes of disseminated TB (dTB). DESIGN: A cohort of patients diagnosed with TB between 2007 and 2013 was retrospectively analysed. Patients with dTB criteria were characterized and compared to single organ TB cases. Factors independently associated with dTB were determined by multivariate logistic regression analysis. RESULTS: A total of 744 patients were analysed, including 145 with dTB. Independent risk factors for dTB were pharmacological immunosuppression (OR 5.6, 95% CI 2.8-11.3), HIV infection (OR 5.1, 95% CI 3.1-8.3), chronic liver failure or cirrhosis (OR 2.3, 95% CI 1.4-4.1) and duration of symptoms (OR 2.3, 95% CI 1.4-3.8). Compared to single organ TB, the clinical presentation of dTB patients differed by the absence of haemoptysis (OR 3.2, 95% CI 1.3-8.4) and of dyspnoea (OR 1.9, 95% CI 1.2-3.1), presence of weight loss (OR 1.8, 95% CI 1.1-2.9), night sweats (OR 1.7, 95% CI 1.1-2.7) and bilateral lung involvement (OR 4.4, 95% CI 2.8-7.1). Mortality and time until culture conversion were higher for dTB patients, although not reaching statistical significance. CONCLUSION: Immunosuppressive conditions and chronic liver failure or cirrhosis were associated with increased risk of dTB. The haematogenous spread may be dependent on longer symptomatic disease and usually progresses with bilateral lung involvement.

Alkylation-induced colon tumorigenesis in mice deficient in the Mgmt and Msh6 proteins.

O(6)-methylguanine DNA methyltransferase (MGMT) suppresses mutations and cell death that result from alkylation damage. MGMT expression is lost by epigenetic silencing in a variety of human cancers including nearly half of sporadic colorectal cancers, suggesting that this loss maybe causal. Using mice with a targeted disruption of the Mgmt gene, we tested whether Mgmt protects against azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF), against AOM and dextran sulfate sodium (DSS)-induced colorectal adenomas and against spontaneous intestinal adenomas in Apc(Min) mice. We also examined the genetic interaction of the Mgmt null gene with a DNA mismatch repair null gene, namely Msh6. Both Mgmt and Msh6 independently suppress AOM-induced ACF, and combination of the two mutant alleles had a multiplicative effect. This synergism can be explained entirely by the suppression of alkylation-induced apoptosis when Msh6 is absent. In addition, following AOM+DSS treatment Mgmt protected against adenoma formation to the same degree as it protected against AOM-induced ACF formation. Finally, Mgmt deficiency did not affect spontaneous intestinal adenoma development in Apc(Min/+) mice, suggesting that Mgmt suppresses intestinal cancer associated with exogenous alkylating agents, and that endogenous alkylation does not contribute to the rapid tumor development seen in Apc(Min/+) mice.

Heterozygosity for the mouse Apex gene results in phenotypes associated with oxidative stress.

Apurinic/apyrimidinic endonuclease is a key enzyme in the process of base excision repair, required for the repair of spontaneous base damage that arises as a result of oxidative damage to DNA. In mice, this endonuclease is coded by the Apex gene, disruption of which is incompatible with embryonic life. Here we confirm the embryonic lethality of Apex-null mice and report the phenotypic characterization of mice that are heterozygous mutants for the Apex gene (Apex+/-). We show that Apex heterozygous mutant cells and animals are abnormally sensitive to increased oxidative stress. Additionally, such animals manifest elevated levels of oxidative stress markers in serum, and we show that dietary supplementation with antioxidants restores these to normal levels. Apex+/- embryos and pups manifest reduced survival that can also be partially rescued by dietary supplementation with antioxidants. These results are consistent with a proposed role for this enzyme in protection against the deleterious effects of oxidative stress and raise the possibility that humans with heterozygous mutations in the homologous HAP1 gene may be at increased risk for the phenotypic consequences of oxidative stress in cells.

Cancer predisposition in mutant mice defective in multiple genetic pathways: uncovering important genetic interactions.

Mouse models that mimic the human skin cancer-prone disease xeroderma pigmentosum (XP) provide an useful experimental system with which to study the relationship between the DNA repair process of nucleotide excision repair (NER) and ultraviolet- (UV) induced skin carcinogenesis. We have generated Xpc mutant mice and documented their deficiency in the process of NER of UV-induced DNA damage. Xpc mutant mice are highly predisposed to UV-B radiation-induced skin cancer, both in the homozygous and the heterozygous state. The combination of Xpc and Trp53 mutations enhances this predisposition and alters the tumor spectrum observed in single mutant mice. These results suggest a synergism between NER and the function of Trp53 in suppression of cancer. We have examined the mutational spectrum in the Trp53 gene from skin cancers in Trp53+/+ and Trp53+/- mice of all three Xpc genotypes and have found evidence for signature mutations associated with defective NER. In addition, we have demonstrated that Xpc mutant mice are highly predisposed to the induction of lung and liver cancers by treatment with 2-acetylaminofluorene (2-AAF) and N-OH-2-AAF. By combining the Xpc mutation with other mutations in genes involved in repair of DNA damage we have identified additional genetic interactions important in carcinogenesis. The mouse Apex gene is a critical component of the base excision repair (BER) pathway as well as the redox regulation of transcription factors important in growth control and the cellular response to DNA damage. By combining mutations in Xpc, Trp53 and Apex we have obtained genetic evidence for a functional interaction between Apex and Trp53 which probably involves the activation of the Trp53 protein by Apex. Mutations in the mismatch repair (MMR) gene Msh2 also influence the carcinogenesis observed in Xpc Trp53 mutant mice. Our results demonstrate that multiple repair pathways operate in prevention of tumor formation.

Genotype-specific Trp53 mutational analysis in ultraviolet B radiation-induced skin cancers in Xpc and Xpc Trp53 mutant mice.

We have examined the mutational spectrum in the Trp53 gene from UVB radiation-induced skin cancers in Trp53+/+ and Trp53+/- mutant mice of all three possible Xpc genotypes. Mutations were detected in exons 2-10 of the Trp53 coding region in approximately 90% of >80 different skin cancers examined. In contrast to Trp53+/+ mice in which most mutations in the Trp53 gene were located in exons 5-8, the majority of the mutations in Trp53+/- mice were at other exons. We observed a high predilection for C-->T transition mutations at a unique CpG site in codon 122 (exon 4) of the Trp53 gene in Xpc-/- Trp53+/- mice. This site is not part of a pyrimidine dinucleotide. Mutations at this codon, as well as in codons 124 and 210, were observed exclusively in Xpc-/- or Xpc+/- mice. Mutations at the corresponding codons (127 and 213) in the human p53 gene have been reported in skin tumors from human patients with xeroderma pigmentosum. Hence, mutations at codons 122 (125), 124 (127), and 210 (213) may constitute signatures for defective or deficient nucleotide excision repair in mice (humans). In Xpc-/- mice, the majority of mutations were located at C residues in CpG sites, in which the C is presumably methylated. A similar bias can be deduced from studies in human XP individuals.

Ultraviolet B radiation-induced skin cancer in mice defective in the Xpc, Trp53, and Apex (HAP1) genes: genotype-specific effects on cancer predisposition and pathology of tumors.

Mutations in nucleotide excision repair (NER) genes in humans result in the UV-induced skin cancer-prone disease xeroderma pigmentosum (XP). Mouse models that mimic XP have provided an informative experimental system with which to study DNA repair, as well as the molecular pathology of UV radiation-induced skin cancer. We reported previously that mice defective in the Xpc gene (Xpc-/-) are highly predisposed to UVB radiation-induced skin cancer and that the appearance of skin cancer is more rapid in Xpc Trp53 double mutants. Extended studies now demonstrate an increased predisposition to UVB radiation-induced skin cancers in Xpc heterozygous mice compared with normal mice. We also show that Xpc Trp53 double heterozygous mutants are more predisposed to skin cancer than Trp53 single heterozygous mice. No mutations were detected in the cDNA of the remaining Xpc allele, suggesting that haploinsufficiency of the Xpc gene may be operating and is a risk factor for UVB radiation-induced skin cancer in mice. Skin tumors from Xpc-/- mice were exclusively well or moderately well-differentiated squamous cell carcinomas. In Xpc+/+ and Xpc+/- mice, many of the squamous cell carcinomas were less well differentiated. We also documented previously increased predisposition to UV radiation-induced skin cancers in Xpc-/- Apex+/- mice. Here we show the absence of mutations in the cDNA of the remaining Apex allele, a further suggestive indication of haploinsufficiency and its resulting predisposition to skin cancer. The Trp53 and Apex heterozygous conditions altered the skin tumor spectrum to more poorly differentiated forms in all Xpc genotypes.

Defective nucleotide excision repair in xpc mutant mice and its association with cancer predisposition.

Mice that are genetically engineered are becoming increasingly more powerful tools for understanding the molecular pathology of many human hereditary diseases, especially those that confer an increased predisposition to cancer. We have generated mouse strains defective in the Xpc gene, which is required for nucleotide excision repair (NER) of DNA. Homozygous mutant mice are highly prone to skin cancer following exposure to UVB radiation, and to liver and lung cancer following exposure to the chemical carcinogen acetylaminofluorene (AAF). Skin cancer predisposition is significantly augmented when mice are additionally defective in Trp53 (p53) gene function. We also present the results of studies with mice that are heterozygous mutant in the Apex (Hap1, Ref-1) gene required for base excision repair and with mice that are defective in the mismatch repair gene Msh2. Double and triple mutant mice mutated in multiple DNA repair genes have revealed several interesting overlapping roles of DNA repair pathways in the prevention of mutation and cancer.

Mutational inactivation of the xeroderma pigmentosum group C gene confers predisposition to 2-acetylaminofluorene-induced liver and lung cancer and to spontaneous testicular cancer in Trp53-/- mice.

Mice that are genetically engineered to mimic the human hereditary cancer-prone DNA repair-defective disease xeroderma pigmentosum (XP) are highly predisposed to UV radiation-induced skin cancer. It is not clear, however, whether XP mice or humans are predisposed to cancers in other tissues associated with exposure to environmental carcinogens. To test the importance of nucleotide excision repair in protection against chemical carcinogenesis in internal organs, we treated XPC mutant (XPC-/-) mice with 2-acetylaminofluorene and NOH-2-acetylaminofluorene. We observed a significantly higher incidence of chemically induced liver and lung tumors in XPC-/- mice compared with normal and heterozygous littermates In addition, the progression of liver tumors in XPC-/- Trp53+/- mice is accelerated compared with XPC-/- Trp53+/+ animals. Finally, we demonstrate a higher incidence of spontaneous testicular tumors in XPC-/- TrpS3-/- double mutant mice compared with XPC+/+ Trp53-/- mice.

Characterization of defective nucleotide excision repair in XPC mutant mice.

Nucleotide excision repair (NER) is a fundamental process required for maintaining the integrity of the genome in cells exposed to environmental DNA damage. Humans defective in NER suffer from the hereditary cancer-prone disease xeroderma pigmentosum. In order to model this disease in mice a mutation in the mouse XPC gene was generated and used to replace a wild-type XPC allele in mouse embryonic stem cells by homologous recombination. These cells were used to derive XPC mutant mice. Fibroblasts from mutant embryos were more sensitive to the cytotoxic effects of ultraviolet light than wild-type and heterozygous cells. Repair synthesis of DNA following irradiation with ultraviolet light was reduced in these cells, indicating a defect in NER. Additionally, XPC mutant embryo fibroblasts were specifically defective in the removal of pyrimidine (6-4) pyrimidone photoproducts from the non-transcribed strand of the transcriptionally active p53 gene. Mice defective in the XPC gene appear to be an excellent model for studying the role of NER and its interaction with other proteins in the molecular pathogenesis of cancer in mammals following exposure to environmental carcinogens.

Synergistic interactions between XPC and p53 mutations in double-mutant mice: neural tube abnormalities and accelerated UV radiation-induced skin cancer.

The significance of DNA repair to human health has been well documented by studies on xeroderma pigmentosum (XP) patients, who suffer a dramatically increased risk of cancer in sun-exposed areas of their skin [1,2]. This autosomal recessive disorder has been directly associated with a defect in nucleotide excision-repair (NER) [1,2]. Like human XP individuals, mice carrying homozygous mutations in XP genes manifest a predisposition to skin carcinogenesis following exposure to ultraviolet (UV) radiation [3-5]. Recent studies have suggested that, in addition to roles in apoptosis [6] and cell-cycle checkpoint control [7] in response to DNA damage, p53 protein may modulate NER [8]. Mutations in the p53 gene have been observed in 50% of all human tumors [9] and have been implicated in both the early [10] and late [11] stages of skin cancer. To examine the consequences of a combined deficiency of the XPC and the p53 proteins in mice, we generated double-mutant animals. We document a spectrum of neural tube defects in XPC p53 mutant embryos. Additionally, we show that, following exposure to UV-B radiation, XPC p53 mutant mice have more severe solar keratosis and suffer accelerated skin cancer compared with XPC mutant mice that are wild-type with respect to p53.

Psychosocial adaptations of shunted hydrocephalic children.

The personality, psychosomatic symptoms and family characteristics of 55 shunted hydrocephalic children older than four years were studied. Hydrocephalic childrens' self-concept, measured by the Children's Appereception Test, was found to be very significantly poorer than that of the control children. They also frequently showed behaviour disorders of the MBD-type, e.g. concentration difficulties, aggressiveness, fastidious eating and nervousness. The hydrocephalic childrens' families showed very significantly more cohesion and less rigidity, and significantly less authoritarianism than average Finnish families. When examining the parents' attitudes to their sick child, one third of the children were seen to be in a healthy role, with parental expectations realistically related to the child's abilities. One third of the children were seen as "babies", with unnecessarily over-protective attitudes on the part of their parents, and one third as "scapegoats", with accusatory attitudes from their mother and father. Those in the role of "scapegoats" had the poorest perceptual skills, the highest frequencies of behaviour disorders and the poorest self-concept.