Lack of p53 and ras mutations in Helicobacter hepaticus-induced liver tumors in A/JCr mice

Helicobacter hepaticus is a recently discovered bacterium that invades mouse liver causing chronic active hepatitis followed by development of preneoplastic hepatocellular foci, hepatocellular adenomas and carcinomas. This establishes a unique animal model for study of the mechanisms of cancer development due to a chronic bacterial infection. A possible mechanism of bacteria-associated tumorigenesis is mutation of oncogenes or tumor suppressor genes. Since mutations in ras oncogenes have been widely detected in a variety of chemically induced and spontaneous mouse liver tumors and specific mutations in the p53 tumor suppressor gene have been associated with human bladder cancers attributed to chronic schistosomal infection, we studied exons 1 and 2 of the N-, K- and H-ras genes and exons 5-8 of the p53 gene for the presence of point mutations in 25 liver tumors from 10 naturally infected A/JCr mice, ranging in age from 16 to 24 months. The 20 adenomas and five carcinomas varied in size from 0.1 to 2.3 cm and arose in livers characterized by a wide assortment of pathological profiles, including hepatitis, inflammation, hyperplasia, hypertrophy, leukocyte infiltration, necrosis and focal phenotypic alteration. DNA samples extracted from formalin-fixed paraffin-embedded tissues were screened by PCR/SSCP analysis and showed no mutations in the analyzed genes. Complete absence of mutations in ras genes in 25 mouse liver tumors is unusual. Other genes may be targeted or H. hepaticus infection causes liver cancer through other pathways than direct damage to DNA.      

Minor products of reaction of DNA with alpha-acetoxytamoxifen

The drug tamoxifen shows evidence of genotoxicity and induces liver tumours in rats. Covalent DNA adducts have been detected in the liver of rats treated with tamoxifen and these arise, at least in part, from its metabolite alpha-hydroxytamoxifen. This probably undergoes conjugation in the liver tissue to give an ester, which alkylates DNA. We have prepared alpha-acetoxytamoxifen as a model for this reactive intermediate and studied its reaction with DNA in vitro. The products of this reaction were chromatographically identical to DNA adducts found in the liver of rats treated with tamoxifen. We have isolated three of these products as the nucleosides TG1, TG2 and TA1 and identified them by ultraviolet, mass and proton magnetic resonance spectroscopy. TG1 and TG2 were tamoxifen-deoxyguanosine adducts in which the alpha-position of tamoxifen was linked to the amino group of guanine; TG1, (E)-4-[4-[2-(dimethylamino)ethoxy]phenyl]-3,4-diphenyl-2- (9beta-de oxyribofuranosyl-6-oxopurin-2-ylamino)-3-butene; TG2, (Z) isomer of TG1. In TG2, the tamoxifen group had undergone trans-cis isomerization. The minor product TA1 was a tamoxifen-deoxyadenosine adduct, where linkage was through the amino group of adenine: (E)-4-[4- [2-(dimethylamino) ethoxy]phenyl]-3,4-diphenyl-2-(9beta- deoxyribofuranosylpurin -6-ylamino)-3-butene. These three adducts accounted for >90% of the reaction products (approximately 67% TG1, 18% TG2 and 7% TA1); trace products included other stereoisomers of these and dinucleotide adducts which resisted enzymatic digestion.      

Effects of the carcinogen, acrylonitrile, on forestomach cell proliferation and apoptosis in the rat: comparison with methacrylonitrile

Acrylonitrile (AN) and methacrylonitrile (MAN) are two major industrial nitriles used in the production of plastics and acrylic fibers. Whereas AN is a potent acute toxin and carcinogenic in rats, little is known regarding MAN. Current work is part of an overall effort designed to assess the potential toxicity/carcinogenicity of MAN. The present study compares the ability of the two chemicals to induce epithelial proliferation and apoptosis in the forestomach (FS; a target of AN carcinogenicity), liver and glandular stomach (non-targets of AN carcinogenicity) of male F344 rats. AN was administered to rats daily, by gavage, for 6 weeks, at 0.43 and 0.22 mmol/kg. MAN was administered at 0.87 and 0.43 mmol/kg. Both AN and MAN induced a dose-dependent increase in epithelial cell proliferation in the FS of male F344 rats as determined by bromodeoxyuridine (BrdU) incorporation into DNA. In contrast, AN, but not MAN caused a dose-dependent increase in the thickness of the forestomach squamous mucosa. This increased thickness (hyperplasia) was reflected by an increase in the number of total epithelial cells per unit length of mucosa. At doses of AN and MAN which induced a 2.3-fold increase in BrdU incorporation, apoptosis was 5- and 18-fold greater than controls, respectively. Although both MAN and AN caused a similar increase in cell proliferation, the relatively more prominent increase in the apoptotic index of the squamous epithelium of rats exposed to MAN may explain the lack of a detectable increase in the thickness of the mucosa compared to that seen with AN. The disruption of the balance between FS mucosal cell proliferation and apoptosis in favor of a net increase in the number of FS epithelial cells per unit length may contribute to the carcinogenicity of AN. In conclusion, present work demonstrated that AN selectively induced a net enhancement in FS cell proliferation, a site of its carcinogenicity. On the other hand, MAN-induced FS cell proliferation was associated with a parallel increase in apoptosis. The relatively greater increase in apoptosis by MAN may have compensated for the increase in FS mucosal cell proliferation and the lack of observable change in the FS thickness.      

Ciprofloxacin treatment of bacterial endocarditis involving prosthetic material after cardiac surgery

Two children with cyanotic congenital heart disease and Gram negative bacterial infection of prosthetic material after cardiac surgery were treated successfully with oral ciprofloxacin, initially in combination with netilmicin. The use of oral ciprofloxacin allowed prolonged outpatient treatment to be given, avoiding the need for intravenous access and early repeat surgery.     

Transforming growth factor-12 polymorphism and systemic lupus erythematosus

OBJECTIVE: To determine whether transforming growth factor-beta2 (TGF-beta2) gene polymorphism is associated with systemic lupus erythematosus (SLE) susceptibility. TGF-beta is a multifunctional family of cytokines important in tissue repair, inflammation and immunoregulation. SLE is thought to be a T cell dependent autoimmune disorder with T cell dysfunction. Due to its known suppressive effects on interleukin 2 dependent T cell growth, TGF-beta2 is considered to be a candidate SLE susceptibility gene. Furthermore, SLE has been linked with a region to which the TGF-beta2 gene has been mapped. METHODS: Association studies were performed in 3 case-control populations, from Spain. Turkey, and UK, using a TGF-beta2 5'-untranslated region (5'-UTR) 4 base pair (bp) insertion polymorphism. Genotyping was performed using fluorescent labeled polymerase chain reaction product sizing. Results. No significant differences were detected in TGF-beta2 5'-UTR polymorphism allele frequencies between SLE patients and matched controls in the 3 populations studied. CONCLUSION. The 4 bp insertion polymorphism within the TGF-beta2 gene does not appear to be associated with SLE. However, this does not rule out the possible involvement of TGF-beta2 in the disease pathogenesis.     

Osteosarcoma: role of CT in limb-sparing treatment

The computed tomographic (CT) examinations of 17 patients undergoing evaluation for limb-sparing treatment of osteosarcoma were evaluated. In all cases information from CT directly affected the operative approach. The CT findings that helped in planning the operative approach included determination of intramedullary extent and evidence of "skip" metastases, direct extension into an adjacent joint, and neurovascular compromise. Performing CT of the affected bone at 1-cm intervals from the joint above through the joint below and including the contralateral side in the field of view allow precise localization of findings that can direct the operative approach. Close and contiguous scanning intervals allow identification of small intramedullary "skip" metastases that affect the resection margins.     

METALLIC FOREIGN BODY IN LEFT MAIN BRONCHUS (A Case Report)

A child with accidental inhalation of a metallic foreign body into left main bronchus is reported. The foreign body was removed by rigid bronchoscopy. The problems in management are discussed and current literature reviewed.KEY WORDS: Foreign body, Bronchoscopy     

Serum TNF levels in neonatal sepsis and septic shock

Tumor necrosis factor (TNF-alpha) has been implicated as a principal mediator in the pathogenesis of septic shock. TNF-alpha was measured by immunoradiometric assay in serum samples from 23 full-term infants with sepsis (15 with severe infection and 8 with septic shock) and in 20 healthy full-term newborns. Serum TNF-alpha levels were significantly higher in the group with sepsis, at the time of admission to the neonatal intensive care unit, than in the healthy neonates. The highest TNF levels were found in those newborns with septic shock, particularly in those who died. Although the method is far too slow for any clinical routine work, our results suggest that the presence of elevated serum TNF-alpha levels could be considered a sensitive and specific test for predicting septic shock and its clinical outcome.     

Hyperphosphataemia after enemas in childhood: prevention and treatment

The case of a child with severe hyperphosphataemia and symptomatic hypocalcaemia secondary to retention of phosphate administered through an antegrade continence enema is reported. Caution should be exercised with the use of phosphate enemas and prompt action taken to remedy retention. The use of glucose with insulin in the emergency management of acute hyperphosphataemia is discussed.     

Conservative management of azoospermia following steroid abuse

As well as athletes and competitive body builders, recreational body builders attending gymnasia are known to abuse anabolic steroids, using doses from 10- to 40-fold above physiological levels. Androgenic steroids induce hypogonadotrophic hypogonadism with associated azoospermia, leading to infertility. Little literature exists on the treatment of steroid-induced azoospermia following the cessation of abuse. We present four cases of steroid-induced azoospermia, its conservative management and eventual return of normal semen density.