Inferring Size-Based Functional Responses From the Physical Properties of the Medium

First derivations of the functional response were mechanistic, but subsequent uses of these functions tended to be phenomenological. Further understanding of the mechanisms underpinning predator-prey relationships might lead to novel insights into functional response in natural systems. Because recent consideration of the physical properties of the environment has improved our understanding of predator-prey interactions, we advocate the use of physics-based approaches for the derivation of the functional response from first principles. These physical factors affect the functional response by constraining the ability of both predators and prey to move according to their size. A physics-based derivation of the functional response should thus consider the movement of organisms in relation to their physical environment. One recent article presents a model along these criteria. As an initial validation of our claim, we use a slightly modified version of this model to derive the classical parameters of the functional response (i.e., attack rate and handling time) of aquatic organisms, as affected by body size, buoyancy, water density and viscosity. We compared the predictions to relevant data. Our model provided good fit for most parameters, but failed to predict handling time. Remarkably, this is the only parameter whose derivation did not rely on physical principles. Parameters in the model were not estimated from observational data. Hence, systematic discrepancies between predictions and real data point immediately to errors in the model. An added benefit to functional response derivation from physical principles is thus to provide easy ways to validate or falsify hypotheses about predator-prey relationships.

[Inherited kidney stones: A nephrology center experience]

INTRODUCTION

Genetic factors must be considered in etiological diagnosis of urinary lithiasis. The aim of this study was to determine clinical, metabolic characteristics and the progression of hereditary urinary lithiasis in our patients.

METHODS

A retrospective study was conducted between 2008 and 2018 and 60 patients were included. Patients were referred to our department from pediatrics departments to be followed-up in adulthood in 9 cases, for etiological investigation in 42 cases and for chronic renal failure in 9 cases.

RESULTS

Thirty-five men and twenty-five women were enrolled in this study with a M/F sex ratio equal to 1.4. The mean age at the time of diagnosis of the hereditary character of the urinary lithiasis was 28.6years (3months-63years). The average delay between the onset of the lithiasis disease and the etiological diagnosis was 8years (0-42years). We noted 31 cases of cystinuria, 18 cases of primary hyperoxaluria type 1 with two mutations (I244T in 14 cases, 33-34 Insc in 23 cases) and 11 cases of renal tubulopathy. Fourteen patients were affected with chronic renal failure, of which five were in the end-stage renal disease. Crystalluria was positive in 62% of cases. The morpho-constitutional analysis of stones was performed in 37 cases and it contributed to the diagnosis in 29 cases. After an average follow-up of 16years, we noted normal renal function in 42 cases, chronic renal failure in 7 cases, hemodialysis in 10 cases all with primary hyperoxaluria and transplantation in 1 case.

CONCLUSION

The etiological diagnosis of hereditary urinary lithiasis in our study was made with considerable delay. Cystinuria was the most frequent etiology and primary hyperoxaluria was the most serious affection.

LEVEL OF EVIDENCE

4.

Global change-driven effects on dissolved organic matter composition: Implications for food webs of northern lakes

Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial-aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)-the messenger between terrestrial and lake ecosystems-with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.

Retro-peritoneal paraganglioma, diagnosis and management

INTRODUCTION

Paragangliomas, defined as extra-adrenal chromaffin-cells tumors, are rarely located in the retro-peritoneum. Clinical presentation is similar to pheochromocytoma, and mainly depends on the producing character of the tumor. Positive diagnosis requires plasmatic and urinary hormonal assays. Radiological and isotopic explorations are essential before surgery. The only curative therapeutic strategy is surgical, associated to peri-operative prevention and monitoring of the frequently reported hemodynamic and cardiovascular disorders. Outcome depends of the metastatic character of the tumor, the presence of tumor remnant after surgical resection. Genetic study is recommended; the risk of recurrence and association to other neoplasm is more described in genetic forms.

MATERIAL AND METHODS

Authors report 5cases of retro-peritoneal paraganglioma, operated in the department of urology of Hospital, between 2013 and 2017. Observations are about 2men and 3women. Clinical presentation is not always specific and paraganglioma may be discovered fortuitously. Two patients have been operated by coelioscopic approach, midline incision was performed in two other cases, and dorsal lumbotomy associated to a Rutherford-Morrison incision in a patient.

RESULTS

Two patients presented resistant hypertension and palpitation associated to suspect retro-peritoneal masses in imagery and elevated urinary methoxylated derivates before surgery. One patient was asymptomatic and the tumor was discovered in imagery. Per-operative hypertensive crisis and sinus tachycardia occurred in a case. The average follow-up period is 22.8months. Hypertension and palpitation disappeared after surgery. There was no recurrence for all the operated patients.

CONCLUSION

Retro-peritoneal paraganglioma is a rare condition. Symptoms are not specific and clinical presentation may be similar to pheochromocytoma. Abdominal CT-scan and MRI, in association with MIBG scintigraphy are strongly evocative. Histological examination ensures diagnosis. Per-operative cardio-vascular disorders are to consider and must prevented and managed by anesthesiologists. Complete surgical resection is the only curative treatment and avoids recurrences.

Splenogonadal fusion - a rare cause of scrotal swelling: a case report

Background

Splenogonadal fusion is a rare and benign condition. Diagnosis is challenging for clinicians. Despite its indolence, diagnosis is often confirmed after orchidectomy. Surgery is mandatory, particularly to rule out the extremely rare association with malignancy.

Case presentation

We report a case of splenogonadal fusion in a 38-year-old North African man presenting a palpable scrotal mass. We describe clinical aspects, pathogenic hypothesis, radiological features, as well as surgical management principles.

Conclusions

Splenogonadal fusion is rarely suspected and diagnosed preoperatively. A diagnosis is made once an ectopic testicular mass is associated with cryptorchidism and suggestive radiological signs. A better knowledge of the clinical and radiological features of splenogonadal fusion provides an opportunity for conservative surgery.

Maximal power training induced different improvement in throwing velocity and muscle strength according to playing positions in elite male handball players

This study was designed to assess the effect of strength and power training on throwing velocity and muscle strength in handball players according to their playing positions. Twenty-two male handball players were assigned to either an experimental group (n=11) or a control group (n=11) (age: 22.1 ± 3.0 years). They were asked to complete (i) the ball throwing velocity test and (ii) the one-repetition maximum (1-RM) tests for the half-back squat, the pull-over, the bench press, the developed neck, and the print exercises before and after 12 weeks of maximal power training. The training was designed to improve strength and power with an intensity of 85-95% of the 1RM. In addition to their usual routine handball training sessions, participants performed two sessions per week. During each session, they performed 3-5 sets of 3-8 repetitions with 3 min of rest in between. Then, they performed specific shots (i.e., 12 to 40). Ball-throwing velocity (p<0.001) was higher after the training period in rear line players (RL). The training programme resulted in an improvement of 1RM bench press (p<0.001), 1RM developed neck (p<0.001) and 1RM print (p<0.001) in both front line (FL) and RL. The control group showed a significant improvement only in ball-throwing velocity (p<0.01) and 1RM bench press (p<0.01) in RL. A significantly greater improvement was found in ball-throwing velocity (p<0.001), 1RM bench press (p<0.001), and 1RM half-back squat exercises in players of the central axis (CA) compared to the lateral axis (LA) (p<0.01). The power training programme induced significantly greater increases in ball-throwing velocity and muscle strength in FL than RL and in CA than LA axis players.

Transitional Bladder Cell Carcinoma Spreading to the Skin

Cutaneous metastases from bladder malignancies are rare. We report the case of a 74 year old man who underwent cysto-prostatectomy and adjuvant chemotherapy for a pT3b N+ bladder transitional cell carcinoma. Four months later, he presented with skin disseminated pigmented lesions. Skin biopsy confirmed cutaneous metastasis from urothelial carcinoma.

Potential for Local Fertilization: A Benthocosm Test of Long-Term and Short-Term Effects of Mussel Excretion on the Plankton

Mussel aquaculture has expanded worldwide and it is important to assess its impact on the water column and the planktonic food web to determine the sustainability of farming practices. Mussel farming may affect the planktonic food web indirectly by excreting bioavailable nutrients in the water column (a short-term effect) or by increasing nutrient effluxes from biodeposit-enriched sediments (a long-term effect). We tested both of these indirect effects in a lagoon by using plankton-enclosing benthocosms that were placed on the bottom of a shallow lagoon either inside of a mussel farm or at reference sites with no history of aquaculture. At each site, half of the benthocosms were enriched with seawater that had held mussels (excretion treatment), the other half received non-enriched seawater as a control treatment. We monitored nutrients ([PO43-] and [NH4+]), dissolved oxygen and plankton components (bacteria, the phytoplankton and the zooplankton) over 5 days. We found a significant relationship between long-term accumulation of mussel biodeposits in sediments, water-column nutrient concentrations and plankton growth. Effects of mussel excretion were not detected, too weak to be significant given the spatial and temporal variability observed in the lagoon. Effects of mussels on the water column are thus likely to be coupled to benthic processes in such semi-enclosed water bodies.

First Report of Mature Citrus Trees Being Affected by Fusarium Wilt in Tunisia

Citrus is an important crop in Tunisia and over 98% of trees of all varieties are grafted on sour orange rootstock. Since September 2010, unusual wilt symptoms have been observed in Takilsa, Bni-Khaled, and Manzel Bouzalfa fields that eventually caused tree death. The disease was observed on 10- to 25-year-old trees of sweet orange (Citrus sinensis) 'Washington Navel' and on 'Clementine' tangerines (C. tangerina) 'Cassar,' 'Hernandina,' and 'MA3,' all grafted on sour orange (C. aurantum) 'Bigarade Gou Tou.' The most conspicuous symptoms were wilting of sections of the canopy, chlorosis and epinasty of young leaves, and discoloration of vascular tissue. No root rot was observed. The problem was widespread with a disease incidence of 45 to 67%. Similar symptoms were described by Timmer et al. (2) on Mexican lime (C. aurantiifolia) nursery plants and some other species of citrus. Three representative isolates of Fusarium oxysporum Schlechtend.:Fr. from crown were single-spored and identified by the production of characteristic, three- to five-celled, sickle-shaped macroconidia with foot-shaped basal cells, ellipsoid microconidia borne in false heads on short monophialides, and chlamydospores in culture (1). The internal transcribed spacer (ITS) region of rDNA and the elongation factor (TEF 1-α) were amplified with primers ITS1/ITS4 and (TEF1/TEF2), respectively. GenBank accessions of ITS region are KC282838, KC282839, and KC282840, for TEF 1-α region are KF531633, KF537336, and KF537337, showed 99% homology with isolates of F. oxysporum in Fusarium-ID data. Pathogenicity tests were conducted on 7-month-old seedlings of sour orange using 10 plants for each of the three isolates. Prior to inoculation, roots were scraping with a sterile scalpel and plants were dipped in a conidial suspension of F. oxysporum (10⁶ conidia ml^-1) for 10 min. Each seedling was planted in a separate pot containing 0.7 liter of sterile soil. Non-inoculated plants with scraped roots dipped in sterile distilled water served as controls. Plants were irrigated and placed in a greenhouse at 24 ± 2°C and 12-h photoperiod. One month after inoculation, leaf chlorosis was observed and 2 months later, 90% of inoculated plants presented a severe wilt. Symptoms on infected plants were similar to those observed in the field. F. oxysporum was successfully re-isolated from the stems, thereby completing Koch's postulates. Genomic DNA was isolated from the re-isolations and PCR amplification of the ITS region was performed with the same primers. There was 100% nucleotide identity with sequences of the original isolates. To our knowledge, this is the first report of fusarium wilt of citrus trees in Tunisia. The pathogen may represent a new form species because previously, the disease was only reported from lime and lemon. References: (1) J. F. Leslie and B. A. Summerell. Page 256 in: The Fusarium Laboratory Manual. Blackwell Publishing Professional, Hoboken, NJ, 2006. (2) L. W. Timmer et al. Phytopathology 72:698, 1982.

Plant-herbivore-decomposer stoichiometric mismatches and nutrient cycling in ecosystems

Plant stoichiometry is thought to have a major influence on how herbivores affect nutrient availability in ecosystems. Most conceptual models predict that plants with high nutrient contents increase nutrient excretion by herbivores, in turn raising nutrient availability. To test this hypothesis, we built a stoichiometrically explicit model that includes a simple but thorough description of the processes of herbivory and decomposition. Our results challenge traditional views of herbivore impacts on nutrient availability in many ways. They show that the relationship between plant nutrient content and the impact of herbivores predicted by conceptual models holds only at high plant nutrient contents. At low plant nutrient contents, the impact of herbivores is mediated by the mineralization/immobilization of nutrients by decomposers and by the type of resource limiting the growth of decomposers. Both parameters are functions of the mismatch between plant and decomposer stoichiometries. Our work provides new predictions about the impacts of herbivores on ecosystem fertility that depend on critical interactions between plant, herbivore and decomposer stoichiometries in ecosystems.

[Ileocolic intussusception from metastatic renal cell carcinoma]

The lung, the liver, the bone tissue and the brain are the most frequent sites for renal cell carcinoma metastasis. Small bowel metastasis from renal cell carcinoma is rare, with only few cases published. We report the case of ileal metastasis from operated kidney cancer revealed by ileocolic intussusception and causing intestinal obstruction in a 32-year-old woman.

[Cardiac metastasis of renal cell carcinoma, a rare location]

The renal carcinoma is situated in the third rank of the urologic cancers. It is metastatic in a third of the cases, when we made the diagnosis of the cancer. Lungs, bone, the liver, the suprarenal gland and the brain stay metastatic sites of preference. Some metastatic locations are anecdotal and made the object of some publications. We report the case of a cardiac metastasis of renal carcinoma at an old patient 81 years old operated for cardiac tumor.

Short- and long-term outcomes of living donors in Tunisia: a retrospective study

Despite initiatives to increase cadaveric donation, there is still a shortfall in donor organs. Kidneys from living donors now makes a significant contribution to increasing the number of organs available for transplantation in Tunisia. We performed a retrospective study of 405 kidney transplantations, including 321 (79.3%) from living donors performed from June 1986 to December 2007. We obtained information on only 162 (50.4%), namely, 64 men (39.5%) and 98 women (60.5%), whose mean age at the time of donation was 42.3 ± 12.2 years. Twelve (8.22%) perioperative complications occurred: wound infections (n = 4), pneumothorax (n = 4), phlebitis (n = 1), hematomas (n = 2), and urinary infection (n = 1). The mean follow-up period was 117.4 ± 74.4 months. Hypertension occurred in 42 donors (25.9%) with mean values of 134 ± 20 for systolic and 79 ± 10 for diastolic blood pressure. Twelve donors (7.4%) developed proteinuria (mean proteinuria, 0.08 ± 1.25 g/d). Renal insufficiency was found in 28 donors (19.44%), 2 of whom developed chronic renal failure requiring dialysis at intervals of 36 and 84 months. In both cases, we diagnosed a familial form of focal segmental glomerulosclerosis. Two donors (1.2%) died within 10 years after kidney donation due to senility. The relatively favorable outcomes suggest that living-donor kidney transplantation is an acceptable approach, in view of the superior results it yields in recipients. However, efforts to increase the number of cadaveric donors in Tunisia should be made. It is also important to develop a registry of long-term kidney function after kidney donation.

Kidney transplantation: Charles Nicolle Hospital experience

The aim of our retrospective study was to analyze the short- and long-term follow-up of 298 renal transplantations performed between June 1986 and May 2005. All were first transplantations except 4 cases, with 54 from cadaveric and 244 from living donors. The recipients included 196 males and 102 females of overall mean age of 31.21 +/- 8.9 years (range, 16-61 years). A combination of prednisolone and azathioprine was presented for 212 patients or mycophenolate mofetil for 86 patients. Polyclonal or monoclonal antibodies were used as induction therapy in 183 cases. Cyclosporine was administered to 188 cases and tacrolimus only to 16. HLA matching was 0 mismatches (MM) in 65 cases; 1 or 2 MM in 113; 3 MM in 99; and > or =4 MM in 21. Acute tubular necrosis occurred in 45 cases. One hundred eighteen patients experienced at least 1 acute rejection episode: 102 cases (41.8%) among living and 16 (29.6%) among cadaveric kidneys donor (P = .0007). The actuarial patient and graft survival rates at 1, 5, 10, 15, and 20 years were 95.9%, 87.4%, 77.5%, 65.6%, and 60.8%, and 94.9%, 84.5%, 75.4%, 65.4%, and 53%, respectively. Sixty-three patients died and 72 patients returned to dialysis. Our results were comparable to experienced centers. However, the member of kidney transplantations does not match the increased number of patients on renal replacement therapy. It is advisable to promote obtaining organs from brain-dead donors.

When microbes and consumers determine the limiting nutrient of autotrophs: a theoretical analysis

Ecological stoichiometry postulates that differential nutrient recycling of elements such as nitrogen and phosphorus by consumers can shift the element that limits plant growth. However, this hypothesis has so far considered the effect of consumers, mostly herbivores, out of their food-web context. Microbial decomposers are important components of food webs, and might prove as important as consumers in changing the availability of elements for plants. In this theoretical study, we investigate how decomposers determine the nutrient that limits plants, both by feeding on nutrients and organic carbon released by plants and consumers, and by being fed upon by omnivorous consumers. We show that decomposers can greatly alter the relative availability of nutrients for plants. The type of limiting nutrient promoted by decomposers depends on their own elemental composition and, when applicable, on their ingestion by consumers. Our results highlight the limitations of previous stoichiometric theories of plant nutrient limitation control, which often ignored trophic levels other than plants and herbivores. They also suggest that detrital chains play an important role in determining plant nutrient limitation in many ecosystems.

Renal histopathological lesions after lung transplantation in patients with cystic fibrosis

We have analyzed the evolution of renal status beyond the perioperative period in patients with cystic fibrosis (CF) undergoing lung transplantation and presented histological analysis of 15 patients biopsied for an episode of accelerated renal function loss (RFL). Episodes of accelerated RFL after the perioperative period occurred in 32.5% of patients and significantly raised the risk of end-stage renal disease (ESRD) (p < 0.001). The histologic lesions associated with these episodes differed according to the time of onset. Early onset (10 cases) was associated with tubulointerstitial lesions in the form of oxalate nephropathy (50%) and/or a pigmented tubulopathy (80%). This latter was correlated with treatment with antiviral agents (p = 0.002) and aminoside and glycopeptide antibiotics (p = 0.03) administered in the month preceding biopsy. Lesions in late episodes of accelerated RFL (5 cases) were principally vascular: arteriosclerosis and arteriolosclerosis (p = 0.007, p = 0.00002), correlated with diabetic glomerulosclerosis or focal segmental glomerulosclerosis in the absence of prominent diabetic changes. Specific calcineurin-inhibitor nephrotoxicity was present in 93.3% of biopsies associated with thrombotic microangiopathy in 46.7% of cases. The identification of specific etiologies of progressive kidney disease in patients with CF after lung transplantation should permit more effective post-transplant care of these patients.

Avascular osteonecrosis after renal transplantation

Avascular osteonecrosis (AVN) is a serious osseous complication after renal transplantation. Its prevalence clearly decreased from 20% to 4% after introduction of cyclosporine and reduction of steroid doses. The aim of our study was to evaluate the frequency of AVN among kidney transplant recipients and to determine the risk factors by comparing them with a population without AVN. Among 326 kidney transplant recipients between June 1986 and December 2004, 15 patients developed AVN with mean age of 40.86 years, including 11 men and 4 women. Fifteen kidney transplant recipients without AVN were selected to be matched for age, gender, and date of transplantation (control group). Cases of symptomatic AVN were diagnosed by hip X-ray, radioisotope bone scan, or magnetic resonance imaging. AVN was diagnosed at a mean of 3.5 years after transplantation (range, 0.5-13 years). The main localization of AVN was the femoral head in 12 cases and the femoral condyle in 3 cases. We studied the following risk factors: the type of donor (cadaver or living donor), the duration on dialysis before transplantation, the cumulative steroid dose, the acute rejection rate, and the posttransplantation weight gain. Statistical analysis showed that the cumulative steroid dose and the acute rejection rate were higher among the AVN group than the control group (P=.04 and P=.058, respectively). The prevalence of AVN in our population is 4.6%, which is probably an underestimate since these were symptomatic cases. The reduction or early withdrawal of steroids remains the only efficient preventive treatment for AVN.

Stoichiometric constraints on resource use, competitive interactions, and elemental cycling in microbial decomposers

Heterotrophic microbial decomposers, such as bacteria and fungi, immobilize or mineralize inorganic elements, depending on their elemental composition and that of their organic resource. This fact has major implications for their interactions with other consumers of inorganic elements. We combine the stoichiometric and resource-ratio approaches in a model describing the use by decomposers of an organic and an inorganic resource containing the same essential element, to study its consequences on decomposer interactions and their role in elemental cycling. Our model considers the elemental composition of organic matter and the principle of its homeostasis explicitly. New predictions emerge, in particular, (1) stoichiometric constraints generate a trade-off between the R* values of decomposers for the two resources; (2) they create favorable conditions for the coexistence of decomposers limited by different resources and with different elemental demands; (3) however, combined with conditions on species-specific equilibrium limitation, they draw decomposers toward colimitation by the organic and inorganic resources on an evolutionary time scale. Moreover, we derive the conditions under which decomposers switch from consumption to excretion of the inorganic resource. We expect our predictions to be useful in explaining the community structure of decomposers and their interactions with other consumers of inorganic resources, particularly primary producers.

Impact of initial blood pressure on the mortality of diabetics undergoing renal replacement therapy

The aim of this study was to determine the blood pressure (BP) profiles and their impact on mortality among a cohort of uremic diabetics treated by hemodialysis. The studied population includes all type II diabetics starting hemodialysis for end-stage renal disease between 1990 and 1996. There were 221 patients (144 men, 77 women) aged from 37 to 78 years, were all followed until death or December 2003 without any censored data. Survival analysis to identify predictors of death was performed using the actuarial method, Cox proportional model, including systolic, diastolic, mean, and pulse blood pressures (SBP, DBP, MBP, PP). One hundred seventy-eight patients (80.5%) were hypertensive at the start of dialysis. Hypertension preceded the diagnosis of diabetes in eight cases (4.5%); 154 patients (86.5%) received antihypertensive drugs and only 23 (14.9%) had well-controlled hypertension. Our population was subdivided into four groups according to their BP levels at the time of beginning of dialysis; G1 (19.5%): normal BP (SBP [90 to 140] and DBP [60 to 90]); G2 (30.3%): Hypertension stage 1 (SBP [140 to 160] and/or DBP [90 to 100]); G3 (32.1%): hypertension stage 2 (SBP [160 to 180] and/or DBP [100 to 110]); G4 (18.1%) hypertension stage 3 (SBP [180 to 220] and/or DBP [110 to 120]). Mean age and comorbidities were similar among the four groups. During a cumulative follow-up period of 872 patient-years, 191 patients died, representing a rate of 21.9 per 100 patient-years; 20.42% of these deaths occurred during the first 3 months of dialysis. Normotensive patients showed lower survival rates without any significant difference in comparison with those of other hypertensive groups. None of the initial BP parameters (SBP, DBP, PP, MBP, hypertension stages) seemed to influence early or global mortalities, which were rather related to the urgent onset of renal replacement therapy, to age, to serum albumin, and to the score of associated morbidities. We conclude that mortality of our hemodialyzed diabetics was not influenced by the blood pressure parameters recorded at the onset of dialysis.