Dysnatremia in a changing climate: A global systematic review of the association between serum sodium and ambient temperature

OBJECTIVE

Both hyponatremia and hypernatremia have been reported to occur more frequently with higher ambient temperatures, although the underlying mechanisms are not well understood. Global temperatures are rising due to climate change, which may impact the incidence of dysnatremia worldwide. We aimed to identify, collate and critically appraise studies analyzing the relationship between climate measures (outdoor temperature, humidity) and serum sodium concentrations.

DESIGN

Systematic review, reported in accordance with PRISMA guidelines.

METHODS

MEDLINE and Embase were searched with relevant key terms. Studies assessing the effect on serum sodium measurement of elevated temperature or humidity versus a comparator were included.

RESULTS

Of 1466 potentially relevant studies, 34 met inclusion criteria, originating from 23 countries spanning all inhabited continents. The majority (30 of 34, 88%) reported a significant association between outdoor temperature and dysnatremia, predominantly lower serum sodium with increased ambient temperature. Humidity had a less consistent effect. Individuals aged above 65 years, children, those taking diuretics and antidepressants, those with chronic renal impairment or those undertaking physical exertion had increased vulnerability to heat-associated dysnatremia. The risk of bias was assessed to be high in all but four studies.

CONCLUSIONS

Higher ambient temperature is consistently associated with an increased incidence of hyponatremia. We infer that hyponatremia presentations are likely to rise with increasing global temperatures and the frequency of extreme heat events secondary to climate change. Evidence-based public health messages, clinician education and reduction in fossil fuel consumption are necessary to reduce the expected burden on healthcare services worldwide.

Syndrome of Inappropriate Antidiuresis: From Pathophysiology to Management

Hyponatremia is the most common electrolyte disorder, affecting more than 15% of patients in the hospital. Syndrome of inappropriate antidiuresis (SIAD) is the most frequent cause of hypotonic hyponatremia, mediated by nonosmotic release of arginine vasopressin (AVP, previously known as antidiuretic hormone), which acts on the renal V2 receptors to promote water retention. There are a variety of underlying causes of SIAD, including malignancy, pulmonary pathology, and central nervous system pathology. In clinical practice, the etiology of hyponatremia is frequently multifactorial and the management approach may need to evolve during treatment of a single episode. It is therefore important to regularly reassess clinical status and biochemistry, while remaining alert to potential underlying etiological factors that may become more apparent during the course of treatment. In the absence of severe symptoms requiring urgent intervention, fluid restriction (FR) is widely endorsed as the first-line treatment for SIAD in current guidelines, but there is considerable controversy regarding second-line therapy in instances where FR is unsuccessful, which occurs in around half of cases. We review the epidemiology, pathophysiology, and differential diagnosis of SIAD, and summarize recent evidence for therapeutic options beyond FR, with a focus on tolvaptan, urea, and sodium-glucose cotransporter 2 inhibitors.

Diabetes IN hospital - Glucose and Outcomes in the COVID-19 pandemic (DINGO COVID-19): the 2020 Melbourne hospital experience prior to novel variants and vaccinations

BACKGROUND AND AIMS

A relationship between diabetes, glucose and COVID-19 outcomes has been reported in international cohorts. This study aimed to assess the relationship between diabetes, hyperglycaemia and patient outcomes in those hospitalised with COVID-19 during the first year of the Victorian pandemic prior to novel variants and vaccinations.

DESIGN, SETTING

Retrospective cohort study from March to November 2020 across five public health services in Melbourne, Australia.

PARTICIPANTS

All consecutive adult patients admitted to acute wards of participating institutions during the study period with a diagnosis of COVID-19, comprising a large proportion of patients from residential care facilities and following dexamethasone becoming standard-of-care. Admissions in patients without known diabetes and without inpatient glucose testing were excluded.

RESULTS

The DINGO COVID-19 cohort comprised 840 admissions. In 438 admissions (52%), there was no known diabetes or in-hospital hyperglycaemia, in 298 (35%) patients had known diabetes, and in 104 (12%) patients had hyperglycaemia without known diabetes. ICU admission was more common in those with diabetes (20%) and hyperglycaemia without diabetes (49%) than those with neither (11%, P < 0.001 for all comparisons). Mortality was higher in those with diabetes (24%) than those without diabetes or hyperglycaemia (16%, P = 0.02) but no difference between those with in-hospital hyperglycaemia and either of the other groups. On multivariable analysis, hyperglycaemia was associated with increased ICU admission (adjusted odds ratio (aOR) 6.7, 95% confidence interval (95% CI) 4.0-12, P < 0.001) and longer length of stay (aOR 173, 95% CI 11-2793, P < 0.001), while diabetes was associated with reduced ICU admission (aOR 0.55, 95% CI 0.33-0.94, P = 0.03). Neither diabetes nor hyperglycaemia was independently associated with in-hospital mortality.

CONCLUSIONS

During the first year of the COVID-19 pandemic, in-hospital hyperglycaemia and known diabetes were not associated with in-hospital mortality, contrasting with published international experiences. This likely mainly relates to hyperglycaemia indicating receipt of mortality-reducing dexamethasone therapy. These differences in published experiences underscore the importance of understanding population and clinical treatment factors affecting glycaemia and COVID-19 morbidity within both local and global contexts.

Haematological actions of androgens

In this review, we discuss the effects on androgens on the haemopoietic system, focussing largely on the effects of testosterone on erythropoiesis. Stimulation of erythropoiesis is one of the most consistent effects of testosterone treatment observed in clinical trials. In men with anaemia this effect can be beneficial. Conversely, erythrocytosis is one of the most common adverse effects of testosterone treatment with a relative risk of 8.14 (95% CI: 1.87-35.40) estimated by a recent meta-analysis of randomised placebo controlled clinical trials. A reduction in haemoglobin is commonly seen in men receiving androgen deprivation therapy for prostate cancer, and in transwomen receiving gender affirming therapy to reduce serum testosterone. While mechanisms by which androgens regulate erythropoiesis are not fully understood, it is likely that effects on erythropoietic progenitor cells and erythropoietin are involved, with secondary effects on iron metabolism. In contrast, whether androgens exert clinically relevant effects on white blood cells and on platelets requires further study.

Tolvaptan versus fluid restriction in acutely hospitalised patients with moderate-profound hyponatraemia (TVFR-HypoNa): design and implementation of an open-label randomised trial

Background

Current hyponatraemia guidelines are divided on the use of tolvaptan in hospitalised patients with moderate to severe hyponatraemia, due to an uncertain risk-benefit ratio. We will conduct a randomised trial to test the hypothesis that early use of tolvaptan improves the rate of serum sodium correction and clinical outcomes compared with current standard first-line therapy, restriction of fluid intake, without increasing the risk of serum sodium overcorrection.

Methods

We will enrol hospitalised patients with euvolaemic or hypervolaemic hyponatraemia and serum sodium of 115–130 mmol/L at Austin Health, a tertiary care centre in Melbourne, Australia. Participants will be randomised 1:1 to receive either tolvaptan (initial dose 7.5 mg) or fluid restriction (initial limit 1000 ml per 24 h), with titration of therapy based on serum sodium response according to a pre-determined protocol over a 72-h intervention period.

The primary endpoint will be the between-group change in serum sodium over time, from study day 1 to day 4. Secondary endpoints include serum sodium increment in the first 24 and 48 h, proportion of participants with normalised serum sodium, length of hospital stay, requirement for serum sodium re-lowering with intravenous dextrose or desmopressin, cognitive and functional measures (Confusion Assessment Method Short form, Timed Up and Go test, hyponatraemia symptom questionnaire), 30-day readmission rate, treatment satisfaction score and serum sodium 30 days after discharge. The trial will be overseen by an independent Data Safety Monitoring Board. Serum sodium will be monitored every 6–12 h throughout the study period, with pre-specified thresholds for commencing intravenous 5% dextrose if serum sodium rise targets are exceeded.

Discussion

We seek to inform future international guidelines with high-quality data regarding the utility and safety of tolvaptan compared to standard therapy fluid restriction in patients with moderate-severe hyponatraemia in hospital. If tolvaptan use in this patient group is endorsed by our findings, we will have established an evidence-based framework for tolvaptan initiation and monitoring to guide its use.

Trial registration

Australia and New Zealand Clinical Trials Registry ACTRN12619001683123. Registered on December 2 2019

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06237-5.

Bilateral atypical femoral fractures during denosumab therapy in a patient with adult-onset hypophosphatasia

SUMMARY

Hypophosphatasia (HPP) is a rare and under-recognised genetic defect in bone mineralisation. Patients presenting with fragility fractures may be mistakenly diagnosed as having osteoporosis and prescribed antiresorptive therapy, a treatment which may increase fracture risk. Adult-onset HPPhypophosphatasia was identified in a 40-year-old woman who presented with bilateral atypical femoral fractures after 4 years of denosumab therapy. A low serum alkaline phosphatase (ALP) and increased serum vitamin B6 level signalled the diagnosis, which was later confirmed by identification of two recessive mutations of the ALPL gene. The patient was treated with teriparatide given the unavailability of ALP enzyme-replacement therapy (asfotase alfa). Fracture healing occurred, but impaired mobility persisted. HPP predisposes to atypical femoral fracture (AFF) during antiresorptive therapy; hence, bisphosphonates and denosumab are contraindicated in this condition. Screening patients with fracture or 'osteoporosis' to identify a low ALP level is recommended.

LEARNING POINTS

Hypophosphatasia (HPP) is a rare and under-recognised cause of bone fragility produced by impaired matrix mineralisation that can be misdiagnosed as a fragility fracture due to age-related bone loss. Antiresorptive therapy is contraindicated in HPP. Low serum alkaline phosphatase (ALP) provides a clue to the diagnosis. Elevated serum vitamin B6 (an ALP substrate) is indicative of HPP, while identification of a mutation in the ALPL gene is confirmatory. Enzyme therapy with recombinant ALP (asfotase alfa) is currently prohibitively costly. Treatment with anabolic bone agents such as teriparatide has been reported, but whether normally mineralized bone is formed requires further study.

The challenges of post-bariatric surgery hypocalcaemia in pre-existing hypoparathyroidism

SUMMARY

Conventional treatment of hypoparathyroidism relies on oral calcium and calcitriol. Challenges in managing post-parathyroid- and post-thyroidectomy hypocalcaemia in patients with a history of bariatric surgery and malabsorption have been described, but postoperative management of bariatric surgery in patients with established hypoparathyroidism has not. We report the case of a 46-year-old woman who underwent elective sleeve gastrectomy on a background of post-surgical hypoparathyroidism and hypothyroidism. Multiple gastric perforations necessitated an emergency Roux-en-Y gastric bypass. She was transferred to a tertiary ICU and remained nil orally for 4 days, whereupon her ionised calcium level was 0.78 mmol/L (1.11-1.28 mmol/L). Continuous intravenous calcium infusion was required. She remained nil orally for 6 months due to abdominal sepsis and the need for multiple debridements. Intravenous calcium gluconate 4.4 mmol 8 hourly was continued and intravenous calcitriol twice weekly was added. Euthyroidism was achieved with intravenous levothyroxine. Maintaining normocalcaemia was fraught with difficulties in a patient with pre-existing surgical hypoparathyroidism, where oral replacement was impossible. The challenges in managing hypoparathyroidism in the setting of impaired enteral absorption are discussed with analysis of the cost and availability of parenteral treatments.

LEARNING POINTS

Management of hypoparathyroidism is complicated when gastrointestinal absorption is impaired. Careful consideration should be given before bariatric surgery in patients with pre-existing hypoparathyroidism, due to potential difficulty in managing hypocalcaemia, which is exacerbated when complications occur. While oral treatment of hypoparathyroidism is cheap and relatively simple, available parenteral options can carry significant cost and necessitate a more complicated dosing schedule. International guidelines for the management of hypoparathyroidism recommend the use of PTH analogues where large doses of calcium and calcitriol are required, including in gastrointestinal disorders with malabsorption. Approval of subcutaneous recombinant PTH for hypoparathyroidism in Australia will alter future management.

Successful medical management of insulinoma with diazoxide for 27 years

SUMMARY

Despite improvements in localisation techniques and surgical advances, some patients with insulinoma will not be cured by surgery or may not be suitable for surgery. Medical management with diazoxide is an option for such cases. This case report details 27 years of successful management of insulinoma using diazoxide. It has been effective and safe, with only minor adverse effects.

LEARNING POINTS

Long term diazoxide use can be a safe, effective option for insulinoma when it cannot be localised or removed surgically. Common adverse effects include peripheral oedema, hyperuricaemia, and hirsutism. 68Ga-NOTA-exendin-4 PET/CT scan should be considered for insulinoma localisation when other modalities have been unhelpful.

Effects of Oral Contraceptive Androgenicity on Visuospatial and Social-Emotional Cognition: A Prospective Observational Trial

Oral contraceptives (OCs) containing estrogen and progesterone analogues are widely used amongst reproductive-aged women, but their neurocognitive impact is poorly understood. Preliminary studies suggest that OCs improve verbal memory and that OCs with greater androgenic activity may improve visuospatial ability. We sought to explore the cognitive impact of OCs by assessing performance of OC users at different stages of the OC cycle, and comparing this performance between users of different OC formulations according to known androgenic activity. We conducted a prospective, observational trial of OC users, evaluating cognitive performance with CogState software on two occasions: days 7-10 of active hormonal pill phase, and days 3-5 of the inactive pill phase (coinciding with the withdrawal bleed resembling menstruation). Thirty-five OC users (18 taking androgenic formulations, 17 taking anti-androgenic) were assessed. Analysis by androgenic activity showed superior performance by users of androgenic OCs, as compared to anti-androgenic OCs, in visuospatial ability and facial affect discrimination tasks. A growing understanding of cognitive effects of OC progestin androgenicity may have implications in choice of OC formulation for individuals and in future OC development.

Outcomes following detection of low level plasma HIV RNA in HIV-infected patients previously virologically suppressed on antiretroviral therapy: a retrospective observational study

BACKGROUND

Progressively sensitive assays for plasma HIV RNA have led to increased detection of plasma HIV RNA between 20 and 200 copies/ml, known as low level viremia (LLV) when recurrent or persistent, in HIV-infected patients on antiretroviral therapy (ART). The aim of this study was to determine outcomes following initial detection of LLV in an Australian cohort.

METHODS

A retrospective study using the HIV Service Database (Alfred Hospital) included all patients on ART who recorded plasma HIV RNA 20-200 copies/mL following prior virological suppression (viral load (VL) HIV RNA <20 copies/mL) over 2 years (2010 to 2012), with follow-up to June 2013. Factors associated with subsequent virological outcome were assessed via univariate and multivariate analysis.

RESULTS

Of 919 patients managed by The Alfred HIV service, 207 (22.5%) met inclusion criteria. Mean age was 48.8 years, 91.3% were male. During follow-up, 54% patients recorded no further HIV RNA 20-200 copies/mL (viral blip); 39% had recurrent or persistent VL 20-200 copies/mL (LLV); and 7% progressed to virological failure with VL >200 copies/mL. Factors associated with LLV included co-morbid type 2 diabetes, shorter prior virological suppression and lower nadir CD4 cell count. Clinician management of VL 20-200 copies/mL was generally conservative, with infrequent requests for genotypic analysis (3.3% cases) or change in ART (<1% cases).

CONCLUSIONS

LLV following virological suppression is common, and occurred as an isolated viral blip in half the patients. Those patients with persistent or recurrent LLV had higher rates of type 2 diabetes, shorter prior virological suppression and lower nadir CD4 cell count.

Diabetic nephropathy: an insight into molecular mechanisms and emerging therapies

Introduction: Diabetic kidney disease (DKD) is a major cause of morbidity and mortality in diabetes and is the most common cause of proteinuric and non-proteinuric forms of end-stage renal disease (ESRD). Control of risk factors such as blood glucose and blood pressure is not always achievable or effective. Significant research efforts have attempted to understand the pathophysiology of DKD and develop new therapies. Areas covered: We review DKD pathophysiology in the context of existing and emerging therapies that affect hemodynamic and metabolic pathways. Renin-angiotensin system (RAS) inhibition has become standard care. Recent evidence for renoprotective activity of SGLT2 inhibitors and GLP-1 agonists is an exciting step forward while endothelin receptor blockade shows promise. Multiple metabolic pathways of DKD have been evaluated with varying success; including mitochondrial function, reactive oxygen species, NADPH oxidase (NOX), transcription factors (NF-B and Nrf2), advanced glycation, protein kinase C (PKC), aldose reductase, JAK-STAT, autophagy, apoptosis-signaling kinase 1 (ASK1), fibrosis and epigenetics. Expert opinion: There have been major advances in the understanding and treatment of DKD. SGLT2i and GLP-1 agonists have demonstrated renoprotection, with novel therapies under evaluation. Addressing the interaction between hemodynamic and metabolic pathways may help achieve prevention, attenuation or even reversal of DKD.

Examining the relationship between obesity and mental health outcomes among individuals admitted to a level I trauma centre

The increased incidence of obesity in the general population translates into clinicians caring for an increased number of trauma patients with obesity. Previous research has documented the unique anatomical and physiological challenges that clinicians face when caring for trauma patients with obesity; however, little is known about psychological challenges that trauma patients with obesity may also experience in the months following injury. The aim of this study is to determine the relationship between obesity and (i) mental health, (ii) demographic and injury-related variables and (iii) quality-of-life outcomes among trauma patients between hospitalization and 3-months post-injury. This is a prospective, longitudinal study conducted between March 2012 and May 2014 at a single, level I trauma centre in the southwest United States. Inclusion criteria for this convenience sample consisted of patients who were admitted to the trauma or orthopaedic trauma service ≥24 h, medically stable, spoke English or Spanish and ≥18 years of age. In total, 455 eligible patients were consented and enrolled; 343 (70.87%) completed 3-month follow-up. The objective of this study is to investigate the relationship between obesity and mental health among trauma patients in the months following injury. Demographic and injury-related data were also collected; patients' height and weight were used to determine body mass index. Health outcomes were assessed during initial hospitalization and at 3-month follow-up and included depression, post-traumatic stress symptoms, pain and return to work. Prior to data collection, it was hypothesized that obesity would have a negative effect on mental health outcomes among patients 3 months post-injury. The final sample consisted of 343 participants; average age was 46.4 ± 17.3 years; majority male (n = 213, 63%) and Caucasian (n = 231, 69%). Patients with obesity had higher odds of screening positive for depression (odds ratio [OR] = 2.36, P = 0.02) and overweight patients had lower odds of returning to work (OR = 0.31, P = 0.01) 3 months post-injury compared to patients of normal weight (65% vs. 40%). No other significant differences were found. Results of the current study are novel in that they identify psychological challenges that overweight and trauma patients with obesity may experience. These results demonstrate the need for mental health professionals to be involved in follow-up care to extending in the months following injury.

First live birth after uterus transplantation in the United States

Uterus transplantation has proven to be a successful treatment for women with absolute uterine infertility, caused either by the absence of a uterus or the presence of a nonfunctioning uterus. We report the first birth of a healthy child following uterus transplantation in the United States, from a recipient of a uterus allograft procured from an altruistic living donor. Two major modifications from the previously reported live births characterized this uterus transplant. First, the transplanted uterus relied upon and sustained the pregnancy while having only the utero-ovarian vein as venous outflow. The implication is a significantly simplified living donor surgery that paves the way for minimally invasive laparoscopic or robot-assisted techniques for the donor hysterectomy. Second, the time from transplantation to embryo transfer was significantly shortened from prior protocols, allowing for an overall shorter exposure to immunosuppression by the recipient and lowering the risk for potential adverse effects from these medications.

Live nondirected uterus donors: Psychological characteristics and motivation for donation

Emerging research suggests that uterus transplantation is a viable option for women without a uterus who want to become pregnant and carry a child to term. Currently, no knowledge exists regarding nondirected uterus donors. This study (NCT 02656550) explored the baseline psychological characteristics of nondirected uterus donors at a single study site. Of the 62 potential donors who underwent initial screening, 6 nondirected donors were chosen and participated in uterus donation. Participants received a comprehensive evaluation, which included clinical history and psychological assessments. The mean age of the donors was 42 years; most (83%) were white/not Hispanic, and all had a college degree. Current depression was reported by 2 participants, past depression was reported in 2 participants, and past anxiety was reported in 3 participants. Based on several different psychological measures, donors had a higher general well-being than the normative sample, and none of the participants' scores indicated psychological distress. All 6 women indicated that giving another woman an opportunity to carry her own child was a motivation for pursuing uterus donation. Further research on potential psychological motives and gains for the donor as well as long-term effects on donors is crucial for ethical practice.

Living Donor Uterus Transplantation: A Single Center's Observations and Lessons Learned From Early Setbacks to Technical Success

Uterus transplantation is a vascularized composite allograft transplantation. It allows women who do not have a uterus to become pregnant and deliver a baby. In this paper, we analyze the first five cases of living donor uterus transplantation performed in the United States. The first three recipients lost their uterus grafts at days 14, 12, and 6, respectively, after transplant. Vascular complications, related to both inflow and outflow problems, were identified as the primary reason for the graft losses. Two recipients, at 6 and 3 mo, respectively, after transplant, have functioning grafts with regular menstrual cycles. Ultimate success will be claimed only after a live birth. This paper is an in-depth analysis of evaluation, surgical technique, and follow-up of these five living donor uterus transplants. The lessons learned were instrumental in allowing us to evolve from failure to technical and functional success. We aim to share our conclusions and build on knowledge in the evolving field of uterus transplantation.

Zebedee: a novel copia-Ty1 family of transposable elements in the genome of the medically important mosquito Aedes aegypti

We have utilised PCR to directly identify a novel family of copia-Ty1 retrotransposable elements (RTPs) in the genome of the mosquito Aedes aegypti. Two members of the family have been sequenced in their entirety and their structural characteristics determined. ZebedeeI is 3505 bp long and appears to be flanked by 21bp direct repeat sequences. A single open reading frame (ORF) of 972 amino acids has the coding potential for a polyprotein with homology corresponding to the conserved amino acid motifs of Long Terminal Repeat (LTR) retrotransposon protease, integrase and reverse transcriptase. ZebedeeII likewise shares significant homology with these regions and also appears to be flanked by short direct terminal repeat sequences of 22 bp. Fifty copies of the 22 bp repeat sequence are present abutting the 5' end of ZebedeeII, with two (partial) representatives of this repeat sequence being present at the 3' end. The Zebedee family appears to have a low middle repetitive copy number in different strains of Ae. aegypti; and transcripts of the elements have been detected in cultured mosquito cells by RT-PCR. Despite the lack of a gag homologue or the LTR hallmarks of previously characterised copia-Ty1 RTPs, phylogenetic analyses place Zebedee within this group, showing considerable homology to copia from Drosophila melanogaster.

Altered family processes related to an ill family member: a validation study

The purpose of this retrospective descriptive survey was to validate the defining characteristics for altered family processes related to an ill family nursing diagnosis. Using Ferhing's (1987) Diagnostic Cantent Validation Model, data were collected from 58 registered nurses. Clinical nurses submitted 14 defining characteristics not identified by NANDA nor found in the literature. Many of these characteristics expressed the same concepts in different terms from those used by NANDA. The results of this study give credibility to NANDA's conceptually stated defining characteristics and suggest further clinical research.

Adolescents and colposcopy: the use of different procedures to reduce anxiety

OBJECTIVE

Two consecutively occurring studies examined whether using a video colposcope to view this procedure or allowing the female adolescent to watch music videos would reduce anxiety and related body movements.

STUDY DESIGN

Female adolescents who underwent colposcopy were randomly assigned to one of two groups, experimental and control. In study 1, 27 female adolescents were randomly assigned either to view the procedure on a television monitor or to be part of a control group (no visual distraction). In study 2, 30 female adolescents were randomly assigned either to a music video group or to a control group. Studies were completed in a consecutive manner and used the same measures, colposcopic equipment, and professional staff, including physician. Multiple measures of anxiety were used (heart rate, behavior observation, and paper and pencil) before, during, and after the procedure. During each colposcopy the subject's behavior across 10 dimensions was observed and coded. Data were analyzed by chi 2, analysis of variance, and Student t tests.

RESULTS

Study 1 found no significant differences in body movements and anxiety ratings between the video colposcope group and controls. In study 2, subjects who were allowed to watch the music videos demonstrated significantly fewer body movements indicative of pain, required less physician reassurance, and received fewer procedural explanations (p < 0.05).

CONCLUSION

Results suggest that allowing a female adolescent to watch music videos during a colposcopic examination appears to decrease body movements associated with discomfort.

Mariner: Its prospects as a DNA vector for the genetic manipulation of medically important insects

Originally described in Drosophila mauritiana, the mariner transposable element has very recently been identified in 63 other insect species, representing ten insect orders, and including the malaria-vector mosquito, Anopheles gambiae. Ann Warren and Julian Crampton here discuss how transposable elements can be exploited as valuable research tools for the molecular characterization of genomes and as DNA vectors for genome manipulation and the 'creation' of transgenic organisms.

The Aedes aegypti genome: complexity and organization

We describe the use of DNA reassociation kinetics to determine the total genome size and complexity together with the individual complexity and copy number of the single copy, middle repetitive and highly repeated DNA fractions of cell line and larval DNA from the mosquito, Aedes aegypti. The genome of Ae. aegypti is both large and complex, being one third the size of the human genome, and exhibits a short period interspersed repeat pattern. The implications of patterns of sequence arrangement and genome complexities for experiments aimed at isolating specific classes of DNA sequences, such as mobile genetic elements, are discussed.

Pinch grafts--applications in podiatric wound closure

Pinch grafts were initially described in the late nineteenth century as a technique that could be utilized, under selected conditions, to promote wound healing. This procedure remains a viable component of the podiatric surgical armamentarium. There has been relatively little information on this subject in the literature: podiatric, orthopedic, or general medical, during the past several decades. A review of the historic development of the procedure, and case presentations, for examples of current applications, are presented.

Verrucous squamous cell carcinoma

Verrucous squamous cell carcinoma involving the plantar aspect of the foot is a relatively rare and generally slow growing tumor that is capable of great local destruction. Diagnosis is based on history, clinical appearance and, most importantly, deep biopsy. A case report is presented, along with a literature review of the history, treatment and prognosis of this rare entity.

Fibrolipomatous hamartoma of nerve

Fibrolipomatous hamartomas of nerve are rare, benign, fibrofatty malformations of peripheral nerves, most commonly affecting the median nerve. Lower extremity cases are extremely rare. The authors present a very rare case of a fibrolipomatous hamartoma involving the superficial peroneal nerve, and review the literature regarding its clinical presentation and surgical management.

Current therapy for subungual melanoma

Malignant subungual melanoma is an infrequently encountered but often misdiagnosed clinical entity. The podiatric surgeon plays a major role in the early diagnosis and surgical management. An illustrative case report of its clinical presentation and a thorough review of current therapeutic modalities are presented.