Severe non-pneumonic necrotising infections in children caused by Panton-Valentine leukocidin producing Staphylococcus aureus strains

Two cases of infection with Panton-Valentine Leukocidin (PVL) producing strains of Staphylococcus aureus are reported. A 15-year-old insulin dependent diabetic developed toxic shock syndrome and an abscess in the deep tissue around his left hip. A 34-day-old infant presented with a right orbital cellulitis with an intra-orbital collection and septicaemia. In both cases PVL-producing strains of Staphylococcus aureus were isolated. Both surgery and prolonged antibiotic combination regimens were required to eradicate the infection. The cases reported here demonstrate the wide range of clinical presentations seen with PVL producing strains, which have so far been mainly associated with furuncles and necrotising pneumonia.

Juvenile thyrotoxicosis; can we do better?

Thyrotoxicosis remains a frustrating condition for the young person, family, and health professionals involved. The associated symptoms do not always suggest thyroid disease and patients can be unwell for many months before the diagnosis is made. The antithyroid drug regimen used to treat children and adolescents with thyrotoxicosis varies from one unit to another and yet the potentially life threatening side effects and remission rates post-treatment may be related to the regimen used. Most patients with thyrotoxicosis will need many years of drug therapy if the thyroid gland is not removed surgically or destroyed by radioiodine. Even "definitive" treatment will typically necessitate thyroxine replacement for life.

Borjeson-Forssman-Lehmann syndrome and multiple pituitary hormone deficiency

We describe two brothers with Borjeson-Forssman-Lehmann syndrome and the 22A-->T (Lys8X) PHF6 mutation, who presented with the symptoms and signs of multiple pituitary hormone deficiency. Biochemical investigations and radiology confirmed growth hormone (GH), thyroid stimulating hormone (TSH) and adrenocorticotrophic hormone (ACTH) as well as gonadotrophin deficiency. They were also found to have optic nerve hypoplasia. This family suggests that the BFL gene product may play an important role in midline neuro-development including the hypothalamo-pituitary axis.

Cardiovascular malformations in infants of diabetic mothers

OBJECTIVE

To compare the prevalence at live birth and the spectrum of cardiovascular malformations in infants born to diabetic mothers with pre-existing diabetes with that in infants of non-diabetic mothers.

DESIGN

Prospective study of all live births in the resident population of one health region, with recording of details of the outcome of all pregnancies of women with pre-existing diabetes and of all live born babies with cardiovascular malformations.

RESULTS

In the six years 1995-2000 there were 192 618 live births in the study population. Cardiovascular malformations were confirmed in 22 of 609 (3.6%) babies with diabetic mothers and in 1417 of 192 009 (0.74%) babies with non-diabetic mothers. The odds ratio for a cardiovascular malformation with maternal diabetes was 5.0 (95% confidence interval 3.3 to 7.8). Combination of these results with previous reports and comparison with the spectrum of cardiovascular malformations in infants of non-diabetic mothers shows a greater than threefold excess of transposition of the great arteries, truncus arteriosus, and tricuspid atresia.

CONCLUSIONS

Pre-existing maternal diabetes is associated with a fivefold increase in risk of cardiovascular malformations. Transposition of the great arteries, truncus arteriosus, and tricuspid atresia are overrepresented to produce a substantial excess of these malformations.

Heat Transfer Ahead of a SAGD Steam Chamber: A Study of Thermocouple Data From Phase B of the Underground Test Facility (Dover Project)

Abstract

Phase B at the Underground Test Facility (Dover Project) is the longest running and most instrumented SAGD pattern in the world and is operated by Devon Canada (formerly Northstar Energy Corporation). Techniques are presented which allow for the interpretation of temperature data from the pilot to better understand the growth of a SAGD steam chamber over time. Calculating the rate and direction of steam chamber movement, the in situ thermal diffusivity and the role of conduction and convection in heat transfer provide a foundation for understanding the interaction between the SAGD recovery process and the reservoir.

Introduction

Over 12 years have passed since the first field test of the classical SAGD recovery process at the Underground Test Facility (UTF) near Fort McMurray, Alberta, Canada. In recent years the level of activity in thermal heavy oil has increased dramatically in Canada. Butler has identified four commercial SAGD projects currently under construction or where construction is to commence soon, and two additional projects were recently announced, all of which could total over one half million barrels per day of production by 2010(1). One of the most striking characteristics of the SAGD technology is that it has undergone relatively little change since its first field trial. Fundamentally, the commercial projects which are currently under construction look very much like the original 50 m Phase A horizontals, placed on production in 1988.

One reason for little change in the SAGD technology is that, so far, it has delivered excellent results. The early piloting of the SAGD process at the UTF has proven that the SAGD process can deliver good rates and reserves from the reservoir at the UTF, which is considered to be inferior to 1/3 of the Athabasca resource(2). In spite of this perception that the UTF reservoir is marginal, the first commercial length wellpairs at Phase B were highly successful, reaching a normalized productivity of 0.2 m3/d per metre of well length(3).

In addition to the success of the SAGD process in recovering oil, SAGD also benefits from the fact that the performance of the early pilots was highly predictable. Butler's equation(4), developed without the benefit of any field data, has been shown to accurately predict the performance of SAGD in the field. The high predictability of the process has meant that the results of early pilots, especially the UTF pilot, have been used to history match simulation models, which have been, in turn, used to predict the performance of SAGD in new reservoirs. In fact, the subject of much of the literature on SAGD is the results of simulation modeling(5–7). At times, the results of simulation modelling are used as a basis for scientific conclusion, typically reserved for real field evidence. Relatively little actual field data is available in the public domain, which exacerbates the situation. Typically, when a new reservoir process is developed and tested in the field, a great effort is required in studying the underlying physics of the process in light of the field data, prior to simulating the process.

Successful radioiodine treatment in a 3 year old child with Graves' disease following antithyroid medication induced neutropenia

A 3 year old child with Graves' disease and mitral valve prolapse became neutropenic on carbimazole therapy. She was switched to propylthiouracil but the neutropenia recurred. She was treated with radioiodine but required two doses of 113 MBq and then 198 MBq five months later before becoming hypothyroid. The mitral valve prolapse resolved when she was euthyroid on thyroxine replacement. Antithyroid drugs, surgery, and radioiodine all have a place in the management of the thyrotoxic child.

Purification and characterization of human cell--cell adhesion molecule 1 (C-CAM1) expressed in insect cells

The cell--cell adhesion molecule 1 (C-CAM1) plays an important role as a tumor suppressor for prostate cancer. Decreased expression of C-CAM1 was detected in prostate, breast, and colon carcinoma. Reexpression of C-CAM1 in prostate and breast cancer cell lines was able to suppress tumorigenicity in vivo. These observations suggest that C-CAM1 may be used as a marker for cancer detection or diagnosis. To generate monoclonal antibodies specific to C-CAM1, we have overexpressed full-length human C-CAM1 in Sf9 cells using a baculovirus expression system. The protein was purified 104-fold using nickel affinity chromatography. About 0.4 mg purified C-CAM1 was obtained from 200 mg of infected cells. When the purified protein was digested with peptidyl-N-glycosidase, the apparent mobility of the protein on SDS--PAGE changed from 90 to 58 kDa, which is close to the molecular weight predicted from the cloned cDNA sequence. This observation suggests that C-CAM1 was glycosylated on asparagine residues when expressed in Sf9 cells. Western blotting and internal protein sequencing analysis confirmed that the purified protein is human C-CAM1. Biochemical and functional assays indicate that this protein expressed in Sf9 cells displays characteristics similar to those of native protein, including adhesion function and glycosylation modification. Using this protocol, sufficient quantity of this protein can be produced with purity suitable for monoclonal antibody generation and biochemical study.

An investigation of the molecular basis for the synergistic interaction of tirapazamine and cisplatin

PURPOSE

To determine if the observed tirapazamine (TPZ)-cisplatin synergistic cell kill was mediated at the cellular level by impairment of upregulation of key proteins involved in repair of DNA interstrand crosslinks. Cisplatin sensitivity has been shown to be dependent on the expression of the two DNA repair proteins ERCC1 and XPA. ERCC1 expression has also been shown to be upregulated by cisplatin exposure. Therefore, these studies were undertaken to determine if hypoxia-activated TPZ pretreatment inhibited the cells' normal protective response to cisplatin via inhibiting the upregulation of ERCC1 and/or XPA expression.

METHODS AND MATERIALS

Two different cell lines, one cisplatin sensitive and one cisplatin resistant, were treated with TPZ, cisplatin, both drugs together (which results in additive cytotoxicity), or TPZ followed by cisplatin (which results in synergistic cytotoxicity). All cells were exposed to 1 h of hypoxia to bioactivate the TPZ. Expression of ERCC1 and XPA were evaluated at the mRNA and protein level at 24 or 48 h after drug exposure.

RESULTS

In the cisplatin-sensitive non-small-cell lung cancer cell line, ERCC1 expression at the mRNA or protein level was not significantly altered in any of the treatment groups. In the cisplatin-resistant ovarian cancer cell line, ERCC1 expression was upregulated by TPZ, but not by cisplatin alone. The change in protein expression was less pronounced than the change in mRNA level. XPA expression was not significantly changed from baseline in either cell line at the mRNA or protein level.

CONCLUSION

In contrast to reports in the literature, this study did not demonstrate cisplatin inducing its own repair by upregulating the DNA crosslink repair proteins ERCC1 or XPA. Therefore, the TPZ-cisplatin synergism cannot be mediated through hypoxia-activated TPZ inhibiting this cellular protective response. TPZ alone, however, was able to alter repair protein expression, which may play a role in mediating its cytotoxicity.

Mutation analysis of BRCA1 and BRCA2 cancer predisposition genes in radiation hypersensitive cancer patients

PURPOSE

The dose intensity of radiotherapy (RT) used in cancer treatment is limited in rare individuals who display severe normal tissue reactions after standard RT treatments. Novel predictive assays are required to identify these individuals prior to treatment. The mechanisms responsible for such reactions are unknown, but may involve dysfunction of genes involved in the sensing and response of cells to DNA damage. The breast cancer susceptibility genes BRCA1 and BRCA2 are implicated in DNA damage repair and the control of genome stability. The purpose of this study was to determine if clinical radiation hypersensitivity is related to mutations of the BRCA1 and BRCA2 genes. Such information is of potential use in the clinical management of BRCA mutation carriers and their families.

METHODS AND MATERIALS

Twenty-two cancer patients who developed severe normal tissue reactions after RT were screened for mutations of BRCA1 and BRCA2, using various methods including protein truncation testing, direct DNA sequencing, and a PCR-based BRCA1 exon 13 duplication test.

RESULTS

No mutations were detected in the 22 patients tested, despite screening for the majority of commonly described types of mutations of BRCA1 and BRCA2.

CONCLUSION

These early results suggest that genes other than BRCA1 and BRCA2 probably account for most cases of clinical radiation hypersensitivity, and that screening for mutations of BRCA1 and BRCA2 is unlikely to be useful in predicting response to radiotherapy. However, it has not been excluded that some BRCA1 or BRCA2 heterozygotes might experience unexpected RT toxicity; further BRCA mutation screening on radiation sensitive individuals is warranted.

Assessment of a 1-year teaching programme in Zanzibar, Tanzania

We assessed whether a 1-year teaching programme in northern Zanzibar would improve prescribing practice. Data on polypharmacy and appropriateness of the treatment of upper-respiratory infection, anaemia, and scabies from the 17 primary health-care units in northern Zanzibar were analysed before and after the teaching programme. There was a significant and sustained reduction in polypharmacy and an improvement in the treatment of upper-respiratory infection, scabies, and anaemia. This teaching programme has been successful in improving prescribing practices in a less-developed country.

Premedication before intubation in UK neonatal units

AIMS

To establish the extent and type of premedication used before intubation in neonatal units in the United Kingdom.

METHODS

A structured telephone survey was conducted of 241 eligible units. Units were subdivided into those that routinely intubated and ventilated babies (routine group) and those that transferred intubated and ventilated babies (transfer group).

RESULTS

Of the units contacted, 239 (99%) participated. Only 88/239 (37%) gave any sedation before intubating on the unit and only 34/239 (14%) had a written policy covering this. Morphine was used most commonly (66%), with other opioids and benzodiazepines used less frequently. Of the 88 units using sedation, 19 (22%) also used paralysis. Suxamethonium was given by 10/19 (53%) but only half of these combined it with atropine. Drug doses varied by factors of up to 200, even for commonly used drugs.

CONCLUSION

Most UK neonatal units do not sedate babies before intubating, despite evidence of physiological and practical benefits. Only a minority have written guidelines, which prohibits auditing of practice.

Localization of a portion of extranuclear ATM to peroxisomes

The gene mutated in the human genetic disorder ataxia-telangiectasia codes for a protein, ATM, the known functions of which include response to DNA damage, cell cycle control, and meiotic recombination. Consistent with these functions, ATM is predominantly present in the nucleus of proliferating cells; however, a significant proportion of the protein has also been detected outside the nucleus in cytoplasmic vesicles. To understand the possible role of extra-nuclear ATM, we initially investigated the nature of these vesicles. In this report we demonstrate that a portion of ATM co-localizes with catalase, that ATM is present in purified mouse peroxisomes, and that there are reduced levels of ATM in the post-mitochondrial membrane fraction of cells from a patient with a peroxisome biogenesis disorder. Furthermore the use of the yeast two-hybrid system demonstrated that ATM interacts directly with a protein involved in the import of proteins into the peroxisome matrix. Because peroxisomes are major sites of oxidative metabolism, we investigated catalase activity and lipid hydroperoxide levels in normal and A-T fibroblasts. Significantly decreased catalase activity and increased lipid peroxidation was observed in several A-T cell lines. The localization of ATM to peroxisomes may contribute to the pleiotropic nature of A-T.

ATM is upregulated during the mitogenic response in peripheral blood mononuclear cells

Patients with the human genetic disorder ataxia-telangiectasia (A-T) are characterized by immunodeficiency and a predisposition to develop lymphoid malignancies. The gene mutated in A-T patients, ATM, codes for a high molecular weight protein that is implicated in DNA damage recognition and cell cycle control. The ATM protein does not change in amount or cellular distribution throughout the cell cycle or in response to DNA damaging agents. Because peripheral blood mononuclear cells (PBMCs) are largely in a state of quiescence and can be readily stimulated to enter a proliferative phase and because A-T cells exhibit growth abnormalities and senescence, indicative of a general intracellular defect in signalling, we chose PBMCs to examine the relationship of ATM to the proliferative status of the cell. We show here that ATM protein is present at low levels in freshly isolated PBMCs and increases approximately 6-fold to 10-fold in response to a mitogenic stimulus, reaching a maximum after 3 to 4 days. A similar, but delayed response, was evident in the presence of serum only. This increase in ATM protein was accompanied by an increase in ATM kinase activity. While expression of ATM protein increased during proliferation, ATM mRNA expression was unchanged in stimulated and unstimulated cells and there was no evidence for increased ATM protein stability in the phytohemagglutinin (PHA)-treated cells. In keeping with the reduced levels of ATM in quiescent cells, the extent of radiation-induction of the p53 pathway was significantly lower than in mitogen-stimulated cells. Basal levels of p21 were elevated in quiescent cells, and the response to radiation was negligible or reduced compared with proliferating cells over a 2-hour period. Overall, the data suggest that the increase in ATM protein in proliferating cells is due to posttranscriptional regulation and points to a role for ATM in more general signalling.

Absence of ATM truncations in patients with severe acute radiation reactions

PURPOSE

Severe acute toxicity limits the effective use of radiotherapy in patients who are radiosensitive, and it is not usually possible to identify these radiohypersensitive (R-H) individuals before treatment commences. Five such R-H patients were detected over a 3-year period. We undertook this study to determine whether the severe acute radiohypersensitivity of these five individuals showed any correlation with cellular and molecular parameters known to be abnormal in radiosensitivity-related syndromes such as ataxia-telangiectasia (A-T).

METHODS AND MATERIALS

Lymphoblastoid cells were isolated from fresh blood from the 5 R-H individuals who had previously demonstrated clinical R-H at least 9 months prior to sampling. Lymphoblastoid cell lines (LCLs) were established to determine the extent of postradiation chromosomal aberrations, cell cycle delay, cell proliferation, and tumor suppressor p53 protein stabilization. The polymerase chain reaction (PCR) and protein truncation (PTT) assays were used to test for the possibility of mutations in the gene mutated in A-T, termed ATM.

RESULTS

LCLs derived from R-H subjects retained a significantly higher degree of radiation-induced chromosomal aberrations when compared to normal control LCLs. p53 stabilization by ionizing radiation appeared normal in all but one R-H subject. There was no evidence of A-T gene truncation mutations in any of the R-H subjects tested.

CONCLUSIONS

All R-H subjects in this study had their cellular radiosensitivity confirmed by the chromosomal aberration assay. Delayed p53 stabilization at 4 hours postirradiation in one R-H subject suggested that different etiologies may apply in the radiohypersensitivity investigated in this study.

Testing for mutations of the ataxia telangiectasia gene in radiosensitive breast cancer patients

BACKGROUND AND PURPOSE

To determine if clinical radiosensitivity in breast cancer patients is related to mutations of the ataxia telangiectasia gene (ATM).

MATERIALS AND METHODS

Fifteen patients who had developed a severe late reaction to a standard radiotherapy schedule were examined for evidence of increased in vitro radiosensitivity using the MTT assay. Mutation analysis was performed using a protein truncation assay.

RESULTS

No mutations were detected in the 15 patients despite evidence of increased in vitro radiosensitivity.

CONCLUSIONS

Testing for the ATM gene is unlikely to be useful for predicting clinical response to radiotherapy in breast cancer patients.

Radiosensitive melanoma cell line with mutation of the gene for ataxia telangiectasia

The human melanoma cell lines MM96L, A2058 and HT144 were examined for sensitivity to ionizing radiation and UVB radiation. HT144 demonstrated a significant increase in sensitivity to ionizing and UVB radiation compared with the MM96L and A2058 cells. Sensitivity to both agents was associated with susceptibility to apoptosis. Using a protein truncation assay, a mutation for the gene for ataxia telangiectasia (ATM) was identified in HT144 cells. This was confirmed to be a homozygous mutation by subsequent sequencing of the abnormal region. Protein truncation assay of the other two cell lines showed no abnormality. The results suggest that somatic mutation of the A-T gene may be important in determining tumour radiosensitivity.

Cellular localisation of the ataxia-telangiectasia (ATM) gene product and discrimination between mutated and normal forms

The recently cloned gene (ATM) mutated in the human genetic disorder ataxia-telangiectasia (A-T) is involved in DNA damage response at different cell cycle checkpoints and also appears to have a wider role in signal transduction. Antibodies prepared against peptides from the predicted protein sequence detected a approximately 350 kDa protein corresponding to the open reading frame, which was absent in 13/23 A-T homozygotes. Subcellular fractionation, immunoelectronmicroscopy and immunofluorescence showed that the ATM protein is present in the nucleus and cytoplasmic vesicles. This distribution did not change after irradiation. We also provide evidence that ATM protein binds to p53 and this association is defective in A-T cells compatible with the defective p53 response in these cells. These results provide further support for a role for the ATM protein as a sensor of DNA damage and in a more general role in cell signalling, compatible with the broader phenotype of the syndrome.

Normal tissue radiosensitivity in breast cancer patients

PURPOSE

To investigate whether in vitro radiosensitivity of lymphocytes derived from a blood sample will predict late effects from radiotherapy in breast cancer patients.

METHODS AND MATERIALS

Blood samples were collected from consenting patients who had received radiotherapy for breast cancer. Lymphocytes were extracted and transformed by the Epstein-Barr virus. The resulting lymphoblastoid cell lines (LCLs) were assessed for in vitro radiosensitivity using a tetrazolium-based colorimetric assay (MTT). Survival curves were generated using doses of 0.5 to 2 Gy. For each analysis an LCL derived from an individual with the radiosensitive condition ataxia-telangiectasia (AT) was run as control. Some patients also consented to give skin biopsies from which fibroblast cultures were derived. Clonogenic assays were performed to generate survival curves using doses in the range of 0.5 to 4 Gy. Comparison was made with the data obtained from LCLs. Late effects of radiotherapy were assessed using the Radiation Therapy Oncology Group (RTOG) scoring scheme and compared with the in vitro radiosensitivity data.

RESULTS

LCLs from 56 breast cancer patients were assessed for in vitro radiosensitivity. Surviving fraction to 2 Gy (SF2) generated from survival curves ranged from 0.04-0.35 with coefficient of variation for the whole group of 41%. None of the LCLs equalled the sensitivity of the AT line, but 16% showed equal or greater sensitivity to a line derived from an AT heterozygote. Comparison of LCL and fibroblast radiosensitivity showed reasonable correlation for 12 paired samples (r = 0.64). The majority of patients showed no or minimal effects after radiotherapy (Grade 0, 1 effects) but seven developed a Grade 2 reaction and four a Grade 3 or 4 reaction. Patients with a Grade 2-4 reaction were found to be more sensitive in vitro than those with a Grade 0-1 reaction (p < 0.02).

CONCLUSIONS

The use of the MTT assay to assess LCL radiosensitivity has demonstrated considerable heterogeneity amongst the breast cancer population. The presence of a proportion of patients showing in vitro sensitivity but normal clinical response to radiotherapy would limit the usefulness of the assay for predictive purposes.

Monoclonal antibodies reactive with the breast carcinoma-associated mucin core protein repeat sequence peptide also recognise the ovarian carcinoma-associated sebaceous gland antigen

The monoclonal antibody (Mab) OM-1, which defines the ovarian carcinoma-associated sebaceous gland antigen (SGA), and Mab F36/22, which defines the ductal carcinoma antigen (DCA), were tested for reactivity against a synthetic peptide representing the repeat twenty amino acid sequence of the human polymorphic epithelial mucin core protein plus four amino acids of the adjacent sequence (p1-24). OM-1 bound strongly to the peptide by direct dot blot assay and ELISA and the minimum epitope for OM-1 was shown to be APDTRP(A) by inhibition assay. F36/22 reacted weakly with the peptide under the same conditions and its affinity for peptide in solution was relatively very low. Mab OC125, which defines the ovarian cancer-associated antigen CA125, did not react with the p1-24 peptide. Five other anti-mucin Mabs (HMFG1, HMFG2, BC1, BC2, BC3), previously shown to bind to the p1-24 peptide, reacted strongly with SGA by direct binding and in a sandwich assay with OM-1 as the capture Mab. F36/22 was weakly positive under the same conditions suggesting that both peptide and SGA do not express the optimal epitope for F36/22 binding. These results indicate that SGA and possibly DCA have the repeat sequence core protein of the breast carcinoma-associated human polymorphic epithelial mucin.