Where should teenagers with cancer be treated?

Cancer in teenagers is relatively uncommon. Few health professionals in oncology are familiar with caring for teenagers, although most would acknowledge them as a characterisable clientele with specific needs different to those of others with cancer, whether younger or older. Many of those diagnosed with cancer between 13 and 20 years of age will be cured, often after intensive, toxic and life-changing treatment. The provision of the highly specialised medical and nursing care needed for cancer treatment must go alongside meeting the specific needs associated with this age group, an age of transition from childhood to adulthood. Care provision for teenagers must therefore address the treatment, information, educational, social and other support requirements of teenagers and their families. This must be done through the work of a highly specialised, experienced multidisciplinary team. A dedicated Teenage Cancer Unit (TCU) provides an appropriate environment in which teenagers may feel comfortable and from which such a multidisciplinary team can function. Such units cannot provide every aspect of a teenager's care throughout their cancer journey so must work in harmony with other agencies, particularly those in the community. TCUs are most successful when they are of sufficient size to ensure a critical mass of staff and experience. Not all teenagers with cancer will be treated on a TCU and other models that can meet both medical and age-specific needs are required.

The products of the mitochondrial orf25 and orfB genes are FO components in the plant F1FO ATP synthase

The F(O) portion of the mitochondrial ATP synthase contains a range of different subunits in bacteria, yeast and mammals. A search of the Arabidopsis genome identified sequence orthologs for only some of these subunits. Blue native polyacrylamide gel electrophoresis separation of Arabidopsis mitochondrial respiratory chain complexes revealed intact F(1)F(O), and separated F(1) and F(O) components. The subunits of each complex were analysed by mass spectrometry and matched to Arabidopsis genes. In the F(1)F(O) complex a series of nine known subunits were identified along with two additional proteins matching the predicted products of the mitochondrial encoded orfB and orf25 genes. The F(1) complex contained the five well-characterised F(1) subunits, while four subunits in the F(O) complex were identified: subunit 9, d subunit, and the orfB and orf25 products. Previously, orfB has been suggested as the plant equivalent of subunit 8 based on structural and sequence similarity. We propose that orf25 is the plant b subunit based on structural similarity and its presence in the F(O) complex. Chimerics of orf25, orfB, subunit 9 and subunit 6 have been associated with cytoplasmic male sterility in a variety of plant species, our additional findings now place all these proteins in the same protein complex.

Trauma as an etiologic factor of primary bone lymphoma: a report of 4 cases

Primary bone lymphoma (PBL) is a rare entity. Nevertheless, very high long-term complete remission and survival rates following adriamycin-based chemotherapy alone or combined with involved-field radiation therapy have been reported. While the etiology is unknown, factors comprising local or general immunocompromised states have been suggested. Sporadic cases of local trauma followed by the emergence of primary bone lymphoma have been described. We describe 4 patients who developed primary bone lymphoma following direct trauma to a specific bone area. All 4 are alive with no evidence of disease after being treated with a combined chemo-radiotherapy regimen.

Dietary polyunsaturated fatty acids and colorectal neoplasia

Epidemiology has implicated dietary fat in mortality associated with some of the most common forms of cancer, including those affecting the intestinal tract, breast and prostate. Polyunsaturated fatty acids, and arachidonate in particular, have been unequivocally linked to experimental colorectal carcinogenesis. Dietary, pharmacologic and genetic manipulation of tissue arachidonic acid and its conversion to bioactive lipids has provided insights into pathogenic mechanisms as well as compelling evidence to support rational preventative and therapeutic methods of disease intervention. While it is clear that conversion of arachidonate to prostaglandins and other bioactive lipids contributes significantly to tumorigenesis in the intestinal tract and other organs, it is also clear that no single metabolic pathway or lipid in this complex biochemical network is solely responsible for dietary or pharmacologic benefits evident in epidemiologic studies. We will review some of these data and provide a summary of our own work showing that conversion of arachidonate to prostaglandin E2 contributes significantly to tumor growth through the modulation of apoptosis and cellular proliferation.

The occurrence of Corynosoma strumosum in the grey seal, Halichoerus grypus, caught off the Atlantic coast of Ireland

The occurrence, location and sex ratio of Corynosoma strumosum (Acanthoceophala: Polymorphidae) from 26 juvenile grey seals, Halichoerus grypus, by-caught from around the Inishkea Islands, Co. Mayo, from March to June 1997 were recorded. The location of C. strumosum within the seal did not vary, with all worms being found in the small intestine. The prevalence of infection was 100%, with no other acanthocephalan species being recorded. The mean abundance was 416 (range 80-846) C. strumosum per seal. There was no significant change in abundance by month. The sex ratio of mature female to mature male parasites was 1.2:1. The lengths of female and male worms did not differ significantly.

Arabidopsis thaliana ferrochelatase-I and -II are not imported into Arabidopsis mitochondria

Using in vitro import assays into purified mitochondria and chloroplasts we found that Arabidopsis ferrochelatase-I and ferrochelatase-II were not imported into mitochondria purified from Arabidopsis (or several other plants) but were imported into pea leaf chloroplasts. Other dual targeted proteins could be imported into purified mitochondria from Arabidopsis. As only two ferrochelatase genes are present in the completed Arabidopsis genome, the presence of ferrochelatase activity in plant mitochondria needs to be re-evaluated. Previous reports of Arabidopsis ferrochelatase-I import into pea mitochondria are due to the fact that pea leaf (and root) mitochondria appear to import a variety, but not all chloroplast proteins. Thus pea mitochondria are not a suitable system to either study dual targeting, or to distinguish between isozymes present in mitochondria and chloroplasts.

Mutagenesis and computer modelling approach to study determinants for recognition of signal peptides by the mitochondrial processing peptidase

Determinants for the recognition of a mitochondrial presequence by the mitochondrial processing peptidase (MPP) have been investigated using mutagenesis and bioinformatics approaches. All plant mitochondrial presequences with a cleavage site that was confirmed by experimental studies can be grouped into three classes. Two major classes contain an arginine residue at position -2 or -3, and the third class does not have any conserved arginines. Sequence logos revealed loosely conserved cleavage motifs for the first two classes but no significant amino acid conservation for the third class. Investigation of processing determinants for a class III precursor, Nicotiana plumbaginifolia F1beta precursor of ATP synthase (pF1beta), was performed using a series of pF1beta presequence mutants and mutant presequence peptides derived from the C-terminal portion of the presequence. Replacement of -2 Gln by Arg inhibited processing, whereas replacement of either the most proximally located -5 Arg or -15 Arg by Leu had only a low inhibitory effect. The C-terminal portion of the pF1beta presequence forms a helix-turn-helix structure. Mutations disturbing or prolonging the helical element upstream of the cleavage site inhibited processing significantly. Structural models of potato MPP and the C-terminal pF1beta presequence peptide were built by homology modelling and empirical conformational energy search methods, respectively. Molecular docking of the pF1beta presequence peptide to the MPP model suggested binding of the peptide to the negatively charged binding cleft formed by the alpha-MPP and beta-MPP subunits in close proximity to the H111XXE114H115X(116-190)E191 proteolytic active site on beta-MPP. Our results show for the first time that the amino acid at the -2 position, even if not an arginine, as well as structural properties of the C-terminal portion of the presequence are important determinants for the processing of a class III precursor by MPP.

The expression of alternative oxidase and uncoupling protein during fruit ripening in mango

The expression of alternative oxidase (Aox) and uncoupling proteins (Ucp) was investigated during ripening in mango (Mangifera indica) and compared with the expression of peroxisomal thiolase, a previously described ripening marker in mango. The multigene family for the Aox in mango was expressed differentially during ripening. Abundance of Aox message and protein both peaked at the ripe stage. Expression of the single gene for the Ucp peaked at the turning stage and the protein abundance peaked at the ripe stage. Proteins of the cytochrome chain peaked at the mature stage of ripening. The pattern of protein accumulation suggested that increases in cytochrome chain components played an important role in facilitating the climacteric burst of respiration and that the Aox and Ucp may play a role in post-climacteric senescent processes. Because both message and protein for the Aox and Ucp increased in a similar pattern, it suggests that their expression is not controlled in a reciprocal manner but may be active simultaneously.

Unraveling the role of mitochondria during oxidative stress in plants

The sedentary habit of plants means that they must stand and fight environmental stresses that their mobile animal cousins can avoid. A range of these abiotic stresses initiate the production in plant cells of reactive oxygen and nitrogen species that ultimately lead to oxidative damage affecting the yield and quality of plant products. A complex network of enzyme systems, producing and quenching these reactive species operate in different organelles. It is the integration of these compartmented defense systems that coordinates an effective response to the various stresses. Future attempts to improve plant growth or yield must consider the complexity of inter-organelle signaling and protein targeting if they are to be successful in producing plants with resistance to a broad range of stresses. Here we highlight the role of pre-oxidant, antioxidant, and post-oxidant defense systems in plant mitochondria and the potential role of proteins targeted to both mitochondria and chloroplasts, in an integrated defense against oxidative damage in plants.

Quantification of the common deletion in human testicular mitochondrial DNA by competitive PCR assay using a chimaeric competitor

The "common" 4977 bp deletion in mitochondrial DNA (Delta4977) is commonly used as an indicator of tissue deterioration in ageing and bioenergetic diseases. Deletion levels are normally measured by a serial dilution polymerase chain reaction (PCR) approach, where test reactions are compared with dilutions of control amplifications of DNA from a similar sized stable region of the mitochondrial genome. The end-point of this assay is the dilution that can just detect any PCR product; however, this is an inherently unstable measure. We constructed a chimaeric DNA construct that binds to both control and deletion primers with similar annealing properties. This was used in a competitive PCR assay to quantify Delta4977 in human testicular tissues that had been well-characterized using the serial dilution approach. We found the competitive assay to be highly replicable as it compares the PCR product of the construct with that of test DNA samples during the linear growth phase of the PCR reaction. Moreover, the serial dilution assay was shown to significantly overestimate the amounts of deleted mitochondrial DNA present. The assay promises to throw new light on the role of mitochondrial DNA deletions in tissue dysfunction and ageing, as such deletions can now be determined with high accuracy and repeatability and is much cheaper to apply than real-time fluorescent quantitative PCR.

Validating facemask use for gas exchange analysis in patients with congestive heart failure

PURPOSE

Functional limitation, often associated with congestive heart failure (CHF), is most accurately assessed with measurement of peak VO2 (VO2peak) during exercise testing. VO2peak strongly predicts survival in CHF patients and is used to triage patients for cardiac transplantation. However, the traditional mouthpiece/noseclip equipment used for gas exchange analysis is often cumbersome and uncomfortable. Several alternative facemask designs tested previously in healthy cohorts were inferior to the mouthpiece for measuring VO2peak. In this study, a series of facemasks designed specifically for VO2peak testing (Hans-Rudolph) was employed. Although previously validated in healthy young adults, this apparatus has not been validated in patients with severe CHF.

METHODS

The Hans-Rudolph facemasks were compared with the mouthpiece apparatus in 30 patients with severe CHF. Each subject completed a cardiopulmonary exercise test with each device. Twelve subjects were randomized to evaluate a possible training effect. To enhance recruitment, 18 additional subjects were recruited after they had completed a test with the mouthpiece.

RESULTS

There was no evidence of a training effect and no differences in gas exchange measurements were found between the two devices. The weight-adjusted VO2peak measurements were 17.1 +/- 5.3 ml O2/kg/min for the mouthpiece group and 17.3 +/- 5.6 ml O2/kg/min for the mask group (P = 0.54).

CONCLUSIONS

The facemask was shown to be equivalent to the mouthpiece for measuring VO2peak in CHF patients. Concerns of hypoventilation and decreased VO2peak associated with previous facemask designs were not substantiated. Since successful exercise testing depends on maximal exertion, providing a choice of equipment may facilitate cooperation without sacrificing accuracy.

Differentially expressed DNA sequences following recovery from unilateral testicular torsion in rat

The molecular response during recovery from torsion-induced stress in the testis is diverse with a variety of mechanisms. In this study, using unilateral testicular torsion in rat as a model, we used subtractive hybridisation to identify differentially expressed DNA sequences in the torsioned and control testes. Three genes were identified as being down regulated in the torsioned testis compared with controls: Control Testis genes 1, 2 and 3 (CT1, CT2 and CT3). Two genes were up regulated in the torsioned testes: Torsioned Testes genes 1 and 2 (TT1 and TT2). Differential expression was confirmed by Reverse Northern blot analysis. An homology search revealed that CT1 had 88% homology with rat metallothionein cDNA; CT2 had 81% homology with rat cell surface antigen in MHC class I, but no homology could be found for CT3. TT1 had 92% identity with rat Rieske iron-sulphur protein mRNA whereas TT2 had 73% identity with a human clone of unknown function (RP 11-252D22). These results indicate that changes in gene expression occur following torsion induced stress, and that identification of differentially expressed genes may provide insights into the mechanisms of cellular tissue damage in this model.

Protein import into plant mitochondria: precursor proteins differ in ATP and membrane potential requirements

The import pathways of the alternative oxidase and the F(A)d subunit of the ATP synthase from soybean were characterised. The F(A)d precursor does not require extramitochondrial ATP for import and this was shown to be a characteristic of the mature protein. The alternative oxidase and F(A)d precursors were shown to differ in their requirement for a membrane potential. The membrane potential was modified using malonate, a competitive inhibitor to complex II. The alternative oxidase could be imported at higher malonate concentrations compared to the F(A)d. This difference could not be ascribed to the number of positive charges in each presequence as would be predicted from similar studies in fungi.

Gaining consent to freeze spermatozoa from adolescents with cancer: legal, ethical and practical aspects

Sperm banking for early adolescent cancer patients requires delicate, sensitive handling and, in the UK, consideration is required of statutory elements. No information at present exists about how adolescents with cancer are normally treated or counselled for sperm banking. Here we highlight the type of issues in relation to fertility preservation faced by clinicians and those faced by adolescents at a sperm storage laboratory. We explore the very real difficulties of bringing together these medical fields of assisted reproduction, oncology and the various pieces of legislation and focus specifically on gaining consent. Attention is paid to counselling and communication to help the patient reach an effective and informed decision to store spermatozoa. The role of parents in contributing towards communication and support, together with the legal constraints in decision making, is acknowledged. How absolute and fully 'informed' consent should be will always remain a contentious issue amongst the various specialists and disciplines. In relation to sperm storage, as a minimum the patients should understand the process that they are undertaking so that it is undertaken freely and without pressure. The practical approach to gaining consent that we are using seems a logical and practical method to help early adolescent patients to store spermatozoa.

Characteristics of patients presenting with central retinal artery occlusion with and without giant cell arteritis

BACKGROUND

In patients with concurrent central retinal artery occlusion (CRAO) and giant cell arteritis (GCA), prompt recognition and early treatment are crucial to prevent further visual loss in the contralateral eye. The objective of this study was to describe a series of patients with CRAO resulting from GCA and to compare them with patients with isolated CRAO.

METHODS

The patient database for a retina service in Philadelphia was searched to identify patients admitted between 1983 and 1993 with a diagnosis of biopsyproven GCA and CRAO. For every patient with CRAO caused by GCA, the next patient admitted for management of acute isolated CRAO was identified; these latter patients constituted the control group. The visual acuity and baseline characteristics of the two groups were compared.

RESULTS

Eleven patients with acute CRAO and GCA were admitted during the study period. In both the case and control groups seven patients (64%) were women and nine patients (82%) were white. Six subjects (54%) in the case group and seven (64%) in the control group had a history of hypertension; the values for diabetes mellitus were two (18%) and zero respectively. Four patients (36%) with CRAO and GCA were cigarette smokers, compared with eight patients (73%) with CRAO alone. None of these differences were statistically significant. Patients with CRAO related to GCA were more likely than those with isolated CRAO to have counting fingers or better vision at presentation (odds ratio 2.22 [95% confidence interval 0.37 to 13.2]), but this trend was not statistically significant.

INTERPRETATION

Patients who presented with CRAO related to GCA were more than twice as likely as those with CRAO alone to have counting fingers or better visual acuity at the time of presentation. However, owing to the small sample, the power of this study to detect a true difference between the two groups was limited.

Torsion-induced injury in rat testes does not affect mitochondrial respiration or the accumulation of mitochondrial mutations

Male rats were subjected to 1 h testicular torsion of the spermatic cord or 1 h torsion followed by detorsion and recovery up to 4 weeks. The extent of tissue damage was evaluated by a testicular biopsy score count and mitochondrial function. Torsion for 1 h followed by detorsion induced significant morphological damage, which became more severe with longer periods of recovery. This morphological damage could not be correlated with mitochondrial damage as assessed by measuring the 4834 bp mitochondrial DNA 'common deletion' using a quantitative competitive polymerase chain reaction (PCR) assay. Mitochondrial respiratory chain activity, as measured by mitochondrial oxygen consumption using an oxygen electrode, did not vary between the treated animals and the controls. We conclude that the common mitochondrial DNA deletion and oxygen consumption are not good indicators of testicular damage induced by torsion.