Dissections of regional lymph nodes for treatment of skin cancer: predicting annual caseloads that will optimise outcomes

IntroductionDissection of regional lymph nodes (RLNs) can lead to significant morbidity and a high prevalence of complications. Published guidance states that these procedures should be carried out by surgeons who are members of a specialist skin multidisciplinary team who carry out a combined minimum of 15 axillary/groin dissections per year. However, there is little evidence to guide this minimum figure of procedures. We report on the burden of service provision and prevalence of complications across the South West of England and Wales.MethodsA 12-month review of dissections of RLNs for skin cancer was undertaken covering five Plastic Surgery Units with a collective catchment of 8.4 million people. Detailed data were collected on patient demographics, pathology, timing of surgery, and prevalence of complications.ResultsA total of 163 dissections were carried out. Forty-three per cent of patients experienced one or more complication. In that 12-month period, an average of 8 axillary/groin dissections was carried out per surgeon. A funnel plot demonstrated that the prevalence of complications for individual surgeons was within the limit of the plot but, in many cases, this was based only on a relatively small number of procedures per consultant. If surgeons carried out 10 procedures per year, the upper and lower limits on the plot were 73% and 11%, respectively.ConclusionsFunnel plots can provide a useful guide as to whether the prevalence of complications for procedures for individual surgeons lies within acceptable limits. Based on these results, 10 procedures per consultant per year should be sufficient to enable meaningful assessment of the prevalence of complications.     

Defects in purine nucleotide metabolism lead to substantial incorporation of xanthine and hypoxanthine into DNA and RNA

Deamination of nucleobases in DNA and RNA results in the formation of xanthine (X), hypoxanthine (I), oxanine, and uracil, all of which are miscoding and mutagenic in DNA and can interfere with RNA editing and function. Among many forms of nucleic acid damage, deamination arises from several unrelated mechanisms, including hydrolysis, nitrosative chemistry, and deaminase enzymes. Here we present a fourth mechanism contributing to the burden of nucleobase deamination: incorporation of hypoxanthine and xanthine into DNA and RNA caused by defects in purine nucleotide metabolism. Using Escherichia coli and Saccharomyces cerevisiae with defined mutations in purine metabolism in conjunction with analytical methods for quantifying deaminated nucleobases in DNA and RNA, we observed large increases (up to 600-fold) in hypoxanthine in both DNA and RNA in cells unable to convert IMP to XMP or AMP (IMP dehydrogenase, guaB; adenylosuccinate synthetase, purA, and ADE12), and unable to remove dITP/ITP and dXTP/XTP from the nucleotide pool (dITP/XTP pyrophosphohydrolase, rdgB and HAM1). Conversely, modest changes in xanthine levels were observed in RNA (but not DNA) from E. coli lacking purA and rdgB and the enzyme converting XMP to GMP (GMP synthetase, guaA). These observations suggest that disturbances in purine metabolism caused by known genetic polymorphisms could increase the burden of mutagenic deaminated nucleobases in DNA and interfere with gene expression and RNA function, a situation possibly exacerbated by the nitrosative stress of concurrent inflammation. The results also suggest a mechanistic basis for the pathophysiology of human inborn errors of purine nucleotide metabolism.     

Disruption of leptin receptor expression in the pancreas directly affects beta cell growth and function in mice

Obesity is characterized by hyperinsulinemia, hyperleptinemia, and an increase in islet volume. While the mechanisms that hasten the onset of diabetes in obese individuals are not known, it is possible that the adipose-derived hormone leptin plays a role. In addition to its central actions, leptin exerts biological effects by acting in peripheral tissues including the endocrine pancreas. To explore the impact of disrupting leptin signaling in the pancreas on beta cell growth and/or function, we created pancreas-specific leptin receptor (ObR) KOs using mice expressing Cre recombinase under the control of the pancreatic and duodenal homeobox 1 (Pdx1) promoter. The KOs exhibited improved glucose tolerance due to enhanced early-phase insulin secretion, and a greater beta cell mass secondary to increased beta cell size and enhanced expression and phosphorylation of p70S6K. Similar effects on p70S6K were observed in MIN6 beta cells with knockdown of the ObR gene, suggesting crosstalk between leptin and insulin signaling pathways. Surprisingly, challenging the KOs with a high-fat diet led to attenuated acute insulin secretory response to glucose, poor compensatory islet growth, and glucose intolerance. Together, these data provide direct genetic evidence, from a unique mouse model lacking ObRs only in the pancreas, for a critical role for leptin signaling in islet biology and suggest that altered leptin action in islets is one factor that contributes to obesity-associated diabetes.     

Characterization and ontogeny of synapse-associated proteins in the developing facial and hypoglossal motor nuclei of the Brazilian opossum

The characterization and ontogeny of synapse-associated proteins in the developing facial and hypoglossal motor nuclei were examined in the Brazilian opossum (Monodelphis domestica). Immunohistochemical markers utilized in this study were the synaptic vesicle-associated proteins synaptophysin and synaptotagmin; a synaptic membrane protein, plasma membrane-associated protein of 25 kDa (SNAP-25); a growth cone protein, growth-associated phosphoprotein-43 (GAP-43); and the microtubule-associated proteins axonal marker τ and dendritic marker microtubule-associated protein-2 (MAP-2). In this study, we have found that during the first 10 postnatal days (1–10 PN), the facial motor nucleus lacked immunoreactivity for synaptophysin, synaptotagmin, GAP-43, τ, and SNAP-25. After 10 PN, immunoreactivity increased in the facial motor nucleus for synaptophysin, synaptotagmin, GAP-43, and τ, whereas immunoreactivity for SNAP-25 was not evident until between 15 and 25 PN. Conversely, immunoreactivity for MAP-2, was present in the facial motor nucleus from the day of birth. In contrast, the hypoglossal motor nucleus displayed immunoreactivity from 1 PN for synaptophysin, synaptotagmin, SNAP-25, GAP-43, τ, and MAP-2. These results suggest that the facial motor nucleus of the opossum may not receive afferent innervation as defined by classical synaptic markers until 15 PN and, further, that characteristic mature synapses are not present until between 15 and 25 PN. These results indicate that there may be a delay in synaptogenesis in the facial motor nucleus compared to synaptogenetic events in the hypoglossal motor nucleus. Because the facial motor nucleus is active prior to completion of synaptogenesis, we suggest that the facial motoneurons are regulated in a novel or distinct manner during this time period. © 1996 Wiley-Liss, Inc.     

Expression of various multidrug resistance-associated protein (MRP) homologues in brain microvessel endothelial cells

Multidrug resistance-associated protein (MRP) actively transports a broad range of anionic compounds out of the cell. To date, six different homologues of MRP (i.e. MRP1-MRP6) have been identified. The current study examines the expression of the various MRP homologues in both primary cultured bovine brain microvessel endothelial cells (BBMEC) and the capillary-enriched fraction from bovine brain homogenates. RT-PCR analysis demonstrated the presence of MRP1, MRP4, MRP5 and MRP6 in both BBMEC and the capillary-enriched fractions of brain homogenates. While low levels of MRP3 were detected in the BBMEC, it was not observed in the capillary-enriched fraction. In addition, RT-PCR and Western blot studies indicated an absence of MRP2 expression in both blood-brain barrier preparations. The presence of several different MRP homologues in the brain microvessel endothelial cells may be important in controlling the permeability of the blood-brain barrier to organic anions.     

Effect of vitamin A adjunct therapy for cerebral malaria in children admitted to Mulago hospital: a randomized controlled trial

Background

Malaria is a leading cause of mortality in Uganda accounting for 25% of deaths among children. Hitherto no adjunct therapy has been identified to improve outcome of cerebral malaria. Retinol suppresses growth of P.falciparum, scavenges free radicals, and exhibits synergistic action with quinine in parasite clearance.

Objective

To determine the effect of vitamin A supplementation on treatment outcome of cerebral malaria

Methods

In this randomised double-blind placebo controlled clinical trial we studied 142 children aged 6–59 months admitted with cerebral malaria in Mulago Hospital, Kampala. Children were randomised to either vitamin A or placebo and followed for 7 days. The main outcome measures were coma recovery time, time for convulsions to stop, and parasite and fever clearance. Secondary outcomes were overall mortality and time taken to start oral feeds.

Results

There was no difference in the coma recovery time (p=0.44), resolution of convulsions (p=0.37), fever clearance (p=0.92), parasite clearance (p=0.12), and starting oral feeds between the two treatment groups. Mortality was higher (16.2%) in the placebo than in the vitamin A group (8.1%): RR 1.4; 95% CI 1.0–2.1.

Conclusions

Vitamin A as adjunct therapy did not significantly reduce coma duration but there were fewer deaths in the vitamin A arm.     

High-fat feeding promotes obesity via insulin receptor/PI3K-dependent inhibition of SF-1 VMH neurons

Steroidogenic factor 1 (SF-1)-expressing neurons of the ventromedial hypothalamus (VMH) control energy homeostasis, but the role of insulin action in these cells remains undefined. We show that insulin activates phosphatidylinositol-3-OH kinase (PI3K) signaling in SF-1 neurons and reduces firing frequency in these cells through activation of K(ATP) channels. These effects were abrogated in mice with insulin receptor deficiency restricted to SF-1 neurons (SF-1(ΔIR) mice). Whereas body weight and glucose homeostasis remained the same in SF-1(ΔIR) mice as in controls under a normal chow diet, they were protected from diet-induced leptin resistance, weight gain, adiposity and impaired glucose tolerance. High-fat feeding activated PI3K signaling in SF-1 neurons of control mice, and this response was attenuated in the VMH of SF-1(ΔIR) mice. Mimicking diet-induced overactivation of PI3K signaling by disruption of the phosphatidylinositol-3,4,5-trisphosphate phosphatase PTEN led to increased body weight and hyperphagia under a normal chow diet. Collectively, our experiments reveal that high-fat diet-induced, insulin-dependent PI3K activation in VMH neurons contributes to obesity development.     

Hepatitis C and blood transfusion among children attending the Sickle Cell Clinic at Mulago Hospital,Uganda

Background

Hepatitis C virus (HCV) accounts for 90% of post-transfusion hepatitis. In Uganda, there has been limited research of prevalence of HCV among sickle cell anaemia (SS) patients, a group at risk for multiple transfusions.

Objectives

To establish prevalence of HCV infection and determine whether blood transfusion increases risk among SS patients.

Methods

244 SS patients aged 1–18 years were recruited by consecutive sampling. Socio-demographic, clinical and transfusion history was collected. Clinical examination done and blood tested for HCV by MEIA.

Results

244 children were recruited. Of these, 159 (65%) had a history of blood transfusion. Among the transfused, five patients were HCV positive. Four of these were over 12 years of age. Among patients with no history of transfusion, one patient aged 14 years was HCV positive. Risk of HCV was higher among the transfused OR 2.7(CI 0.31–24). Patients who received more than two units were more likely to be HCV positive (p=0.03).

Conclusions

HCV prevalence of 2.5% was low but higher than that reported by other investigators in Uganda. Blood transfusion was a major contributing factor in occurrence of HCV. Children who get repeated transfusions should be screened for Hepatitis C and screening of blood for HCV prior to transfusion would help reduce occurrence of the disease.