Permanent phenotypic correction of hemophilia B in immunocompetent mice by prenatal gene therapy

Hemophilia B, also known as Christmas disease, arises from mutations in the factor IX (F9) gene. Its treatment in humans, by recombinant protein substitution, is expensive, thus limiting its application to intermittent treatment in bleeding episodes and prophylaxis during surgery; development of inhibitory antibodies is an associated hazard. This study demonstrates permanent therapeutic correction of his disease without development of immune reactions by introduction of an HIV-based lentiviral vector encoding the human factor IX protein into the fetal circulation of immunocompetent hemophiliac and normal outbred mice. Plasma factor IX antigen remained at around 9%, 13%, and 16% of normal in the 3 hemophilia B mice, respectively, until the last measurement at 14 months. Substantial improvement in blood coagulability as measured by coagulation assay was seen in all 3 mice and they rapidly stopped bleeding after venipuncture. No humoral or cellular immunity against the protein, elevation of serum liver enzymes, or vector spread to the germline or maternal circulation were detected.     

Technical limitations of sentinel node biopsy in breast cancer: a single surgeon's experience

Few studies have attempted to critically identify patient- and tumor-related factors that limit sentinel node biopsy (SNB). These studies have been limited by sample size and surgeon variability. The present study attempts to enumerate these limitations in a unique group of patients. One hundred twenty-five SNBs performed by a single surgeon between May 1997 and June 2001 were reviewed. Overall SNB was successful in 96 per cent of patients with a 97 per cent correlation with the axillary node dissection. Sentinel node identification was not affected by age, tumor size, tumor location, prior segmental resection, or neoadjuvant therapy. No false negatives were noted in the neoadjuvant group. The use of blue dye alone significantly understaged patients when compared with isotope alone (P = 0.02). SNB is a highly accurate method to identify axillary metastases and its limitations are not affected by patient or tumor related factors. In the present study SNB detection by both isotope and blue dye has been shown to be superior to blue dye alone. This finding demonstrates that these limitations may be overcome with the standardization of the technique used.     

Immunochemical detection of UV-induced DNA damage and repair

The application of an antiserum to ultraviolet radiation (UVR)-damaged DNA is presented. A novel experimental system was employed to ascertain the limits of detection for this antiserum. Using a DNA standard containing a known amount of dimer, the limits of detection were found to be 0.9 fmol of dimer. This was compared to a limit of 20–50 fmol dimer using gas chromatography-mass spectrometry (GC-MS). Induction of thymine dimers in DNA following UVR exposure, as assessed using this antiserum in an enzyme-linked immunosorbent assay (ELISA), was compared with GC-MS measurements. The ELISA method successfully demonstrated the induction of lesions in DNA irradiated either with UVC or UVB, although despite high sensitivity, no discernible binding was seen to UVA-irradiated DNA. The antiserum was also shown to be applicable to immunocytochemistry, localising damage in the nuclei of UVR exposed keratinocytes in culture. The ability of the antiserum to detect DNA damage in skin biopsies of individuals exposed to sub-erythemal doses of UVR was also demonstrated. Moreover, the subsequent removal of this damage, as evidenced by a reduction in antiserum staining, was noted in sections of biopsies taken in the hours following irradiation.     

Trauma increases extrahepatic arginase activity

BACKGROUND: Although expressed primarily in the liver, arginase activity also is present in extrahepatic tissues and specifically in macrophages, where it may play diverse physiologic roles in wound healing, cellular proliferation, and the regulation of nitric oxide production. Arginase activity in immune cells is upregulated by certain cytokines such as IL-4, IL-10, and TGF-beta and by catecholamines. Since the release of these substances is increased after trauma, we hypothesized that arginase activity would also be increased in immune cells after trauma. The current work tests this hypothesis. METHODS: A model of surgical trauma was created in C3H/HeN mice by performing an exploratory laparotomy. Tissue arginase activity and arginase I protein expression were determined. As a control, arginase activity and expression were also stimulated with the use of endotoxin. In addition, we evaluated the expression of inducible nitric oxide synthase and the accumulation of nitric oxide metabolites in plasma. RESULTS: Surgical trauma was associated with a significant increase in arginase activity in splenic and renal tissues (P < .05). Splenic macrophages from trauma animals exhibited arginase activity levels approximately 10 times those of controls (P < .05). Endotoxin alone increased arginase activity in the spleen, but this increase was less than that of trauma alone (P < .05). Arginase activity remained elevated after trauma for up to 4 days and normalized by day 7. Arginase I expression was upregulated by trauma in both splenic and renal tissue and by endotoxin in the spleen only. Despite upregulation of inducible nitric oxide synthase in trauma animals, circulating nitric oxide metabolites were decreased 2 days after trauma compared with controls (P < .05). Endotoxin-induced nitric oxide metabolites were also reduced in trauma animals compared with endotoxin treatment alone (P < .05), but this normalized by day 4. CONCLUSIONS: Extrahepatic arginase expression and activity is increased after trauma and may provide the necessary precursors for cellular proliferation and repair or may play a regulatory role in the production of nitric oxide.     

Consent for tonsillectomy

Rulings in recent negligence cases reveal a shift towards what the ‘reasonable patient’ would expect in deciding the risks doctors must disclose to patients. This survey aimed to investigate whether the ‘reasonable patient’ and ‘responsible body of medical opinion’ agree about which risks should be discussed regarding tonsillectomy. Using questionnaires, surgeons were asked which of the 10 complications they routinely discussed and patients were asked how seriously they regarded these complications. The results were compared with the Test of Proportions. Most surgeons routinely mentioned otalgia, odynophagia, throat infection and re‐operation. Most patients regarded potentially fatal bleeding, pneumonia and blood transfusion as very serious but only the minority of surgeons mentioned these (P < 0.001). When obtaining consent for tonsillectomy, surgeons do not routinely mention all the risks that the ‘reasonable patient’ would expect. The ‘reasonable patient’ would expect that re‐operation, transfusion, pneumonia and fatal blood loss are discussed.