The abdomen of <Emphasis Type="Italic">Drosophila</Emphasis>: does planar cell polarity orient the neurons of mechanosensory bristles?

Background

In the adult abdomen of Drosophila, the shafts of mechanosensory bristles point consistently from anterior to posterior. This is an example of planar cell polarity (PCP); some genes responsible for PCP have been identified. Each adult bristle is made by a clone of four cells, including the neuron that innervates it, but little is known as to how far the formation or positions of these cells depends on PCP. The neurons include a single dendrite and an axon; it is not known whether the orientation of these processes is influenced by PCP.

Results

We describe the development of the abdominal mechanosensory bristles in detail. The division of the precursor cell gives two daughters, one (pIIa) divides to give rise to the bristle shaft and socket cell and the other (pIIb) generates the neuron, the sheath and the fifth cell. Although the bristles and their associated shaft and socket cells are consistently oriented, the positioning and behaviour of the neuron, the sheath and the fifth cell, as well as the orientation of the axons and the dendritic paths, depend on location. For example, in the anterior zone of the segment, the axons grow posteriorly, while in the posterior zone, they grow anteriorly. Manipulating the PCP genes can reverse bristle orientation, change the path taken by the dendrite and the position of the cell body of the neuron. However, the paths taken by the axon are not affected.

Conclusion

PCP genes, such as starry night and dachsous orient the bristles and position the neuronal cell body and affect the shape of the dendrites. However, these PCP genes do not appear to change the paths followed by the sensory axons, which must, therefore, be polarised by other factors.

     

Sinonasal lymphomas. Case report

In the field of Otorhinolaryngology sinonasal lymphomas are relatively uncommon and represent less than 1% of all head and neck malignancies. Nowadays, they are regarded as consisting of two distinct subgroups, characterised by phenotype, location, prognosis and treatment. Lymphomas of the B-Cell phenotype are the most frequent type found in the paranasal sinuses. They are less aggressive and carry a relatively better prognosis. T/NK-Cell lymphomas are mostly found in the nasal cavity. They are more aggressive and carry a relatively worse prognosis. We present a case of a 65-year-old patient, who complained with unilateral right-sided nasal obstruction associated with a sensation of right aural fullness. CT scan demonstrated opacity of the posterior ethmoid and sphenoid sinuses on the right side, with evidence of erosion of the anterior wall of the sphenoid. Nasal endoscopy revealed a smooth purple mass, arising from the right superior meatus, which bled on contact, and which was subsequently shown to be, on histological assessment, a malignant high grade lymphoma, non-Hodgkin's B-cell phenotype. Following a discussion of the case we will present a review of these tumours, which have a poor overall prognosis, focusing on epidemiology, sites of origin, symptoms, investigation and management.     

Hyperpolarized 13C magnetic resonance evaluation of renal ischemia reperfusion injury in a murine model

Acute kidney injury (AKI) is a major risk factor for the development of chronic kidney disease (CKD). Persistent oxidative stress and mitochondrial dysfunction are implicated across diverse forms of AKI and in the transition to CKD. In this study, we applied hyperpolarized (HP) ¹³C dehydroascorbate (DHA) and ¹³C pyruvate magnetic resonance spectroscopy (MRS) to investigate the renal redox capacity and mitochondrial pyruvate dehydrogenase (PDH) activity, respectively, in a murine model of AKI at baseline and 7 days after unilateral ischemia reperfusion injury (IRI). Compared with the contralateral sham‐operated kidneys, the kidneys subjected to IRI showed a significant decrease in the HP ¹³C vitamin C/(vitamin C + DHA) ratio, consistent with a decrease in redox capacity. The kidneys subjected to IRI also showed a significant decrease in the HP ¹³C bicarbonate/pyruvate ratio, consistent with impaired PDH activity. The IRI kidneys showed a significantly higher HP ¹³C lactate/pyruvate ratio at day 7 compared with baseline, although the ¹³C lactate/pyruvate ratio was not significantly different between the IRI and contralateral sham‐operated kidneys at day 7. Arterial spin labeling magnetic resonance imaging (MRI) demonstrated significantly reduced perfusion in the IRI kidneys. Renal tissue analysis showed corresponding increased reactive oxygen species (ROS) and reduced PDH activity in the IRI kidneys. Our results show the feasibility of HP ¹³C MRS for the non‐invasive assessment of oxidative stress and mitochondrial PDH activity following renal IRI.     

Assessing high‐intensity focused ultrasound treatment of prostate cancer with hyperpolarized 13C dual‐agent imaging of metabolism and perfusion

The goal of the study was to establish early hyperpolarized (HP) ¹³C MRI metabolic and perfusion changes that predict effective high‐intensity focused ultrasound (HIFU) ablation and lead to improved adjuvant treatment of partially treated regions. To accomplish this a combined HP dual‐agent (¹³C pyruvate and ¹³C urea) ¹³C MRI/multiparametric ¹H MRI approach was used to measure prostate cancer metabolism and perfusion 3–4 h, 1 d, and 5 d after exposure to ablative and sub‐lethal doses of HIFU within adenocarcinoma of mouse prostate tumors using a focused ultrasound applicator designed for murine studies. Pathologic and immunohistochemical analysis of the ablated tumor demonstrated fragmented, non‐viable cells and vasculature consistent with coagulative necrosis, and a mixture of destroyed tissue and highly proliferative, poorly differentiated tumor cells in tumor tissues exposed to sub‐lethal heat doses in the ablative margin. In ablated regions, the intensity of HP ¹³C lactate or HP ¹³C urea and dynamic contrast‐enhanced (DCE) MRI area under the curve images were reduced to the level of background noise by 3–4 h after treatment with no recovery by the 5 d time point in either case. In the tissues that received sub‐lethal heat dose, there was a significant 60% ± 12.4% drop in HP ¹³C lactate production and a significant 30 ± 13.7% drop in urea perfusion 3–4 h after treatment, followed by recovery to baseline by 5 d after treatment. DCE MRI K^trans showed a similar trend to HP ¹³C urea, demonstrating a complete loss of perfusion with no recovery in the ablated region, while having a 40%–50% decrease 3–4 h after treatment followed by recovery to baseline values by 5 d in the margin region. The utility of the HP ¹³C MR measures of perfusion and metabolism in optimizing focal HIFU, either alone or in combination with adjuvant therapy, deserves further testing in future studies.     

In-111-labeled white blood cell uptake in noninfected closed fracture in humans: prospective study

Since indium-111 white blood cell (In-111 WBC) scintigraphy is often used to evaluate for osteomyelitis in bone fractures, it is important to know if noninfected fractures have In-111 WBC uptake. Twenty-seven noninfected closed fracture sites in 19 patients were prospectively evaluated with technetium-99m methylene diphosphonate bone scintigraphy and In-111 WBC scintigraphy. In-111 WBC uptake was present in 41% of the 27 sites. In the 11 positive sites, the In-111 WBC uptake was 1+ (definite but minimal) in 55%, 2+ (moderate) in 36%, and 3+ (marked) in 9%. The visual intensity of the radioactive uptake on In-111 WBC scintigrams relative to that on bone scintigrams was less in 82%, equal in 9%, and greater in 9%. The visual size of the area of uptake on In-111 WBC scintigrams and bone scintigrams was smaller in 36%, equal in 55%, and greater in 9%. Factors that may help distinction of In-111 WBC uptake due to fracture alone from infection associated with fracture are discussed.     

Protectiveness of species sensitivity distribution hazard concentrations for acute toxicity used in endangered species risk assessment

A primary objective of threatened and endangered species conservation is to ensure that chemical contaminants and other stressors do not adversely affect listed species. Assessments of the ecological risks of chemical exposures to listed species often rely on the use of surrogate species, safety factors, and species sensitivity distributions (SSDs) of chemical toxicity; however, the protectiveness of these approaches can be uncertain. We comprehensively evaluated the protectiveness of SSD first and fifth percentile hazard concentrations (HC1, HC5) relative to the application of safety factors using 68 SSDs generated from 1,482 acute (lethal concentration of 50%, or LC50) toxicity records for 291 species, including 24 endangered species (20 fish, four mussels). The SSD HC5s and HCls were lower than 97 and 99.5% of all endangered species mean acute LC50s, respectively. The HC5s were significantly less than the concentrations derived from applying safety factors of 5 and 10 to rainbow trout (Oncorhynchus mykiss) toxicity data, and the HCls were generally lower than the concentrations derived from a safety factor of 100 applied to rainbow trout toxicity values. Comparison of relative sensitivity (SSD percentiles) of broad taxonomic groups showed that crustaceans were generally the most sensitive taxa and taxa sensitivity was related to chemical mechanism of action. Comparison of relative sensitivity of narrow fish taxonomic groups showed that standard test fish species were generally less sensitive than salmonids and listed fish. We recommend the use of SSDs as a distribution-based risk assessment approach that is generally protective of listed species.     

Limp as unusual presentation of Langerhans' cell histiocytosis

An isolated eosinophilic granuloma involving the posterior elements of a lumbar vertebra is reported in a 3-year-old boy presenting with progressive limp. Radiological investigations revealed osteolysis of the L5 right pedicle. MRI showed a well-defined homogeneous mass with nonspecific signal intensity. An unusual feature was the paravertebral muscular location of the largest part of the tumour indicating a possible soft tissue origin. Immunohistochemical studies were typical for Langerhans' cell histiocytosis. Conclusion A limp can be due to lumbar and paravertebral muscular location of Langerhans' cell histiocytosis. Received: 16 June 1998 / Accepted in revised form: 7 October 1998     

Non-Epstein-Barr virus-associated T-cell lymphoma following cardiac transplantation for Barth syndrome

Barth syndrome is a metabolic disease characterized by infantile cardiomyopathy, neutropenia and organic aciduria. We report disease evolution in one of the first affected boys to undergo successful cardiac transplantation. CONCLUSION: Although cardiac status stabilized, he developed disabling skeletal myopathy, protracted lymphopenia and--5 y after transplant--fatal Epstein Barr (EBV)-negative T-cell non-Hodgkin's lymphoma.     

Focal nodular hyperplasia in association with spontaneous intrahepatic portosystemic venous shunt

We report a case of focal nodular hyperplasia in an adolescent with a spontaneous intrahepatic portosystemic venous shunt. Diagnosis was established by duplex and color Doppler ultrasound, computed tomography, magnetic resonance imaging, and histology. This association further supports the hypothesis that focal nodular hyperplasia is a response to a preexisting vascular abnormality.     

Tricuspid valve repair for biopsy-induced regurgitation in a heart transplant recipient

Tricuspid regurgitation (TR) is a frequent complication after heart transplantation. The etiology of TR is multifactorial, but biopsy-induced flail leaflet is one of the most important mechanisms. A 61-year-old woman underwent heart transplant, but experienced several rejection episodes which required multiple surveillance endomyocardial biopsies. At three months after transplant, she required tricuspid valve repair due to symptomatic severe TR. The anterior leaflet was flail, with rupture of primary and secondary chordae. Valve repair was performed with a triple leaflet edge-to-edge technique. The procedure consisted of suture fixation of the prolapsed anterior leaflet joining to the septal and posterior leaflets, and placement of a 30-mm annuloplasty ring. The patient was uneventfully discharged home on day 7 with trivial TR. At a four-years post-transplant evaluation, she was in NYHA functional class I, with preserved ventricular function and trivial TR. She has been followed closely because of post-transplant coronary artery disease.