Steroid treatment in ocular tuberculosis: A double-edged sword?

INTRODUCTION: We report the case of a Caribbean patient with an atypical presentation of bilateral tuberculous chorioretinopathy. PATIENT AND METHODS: A 57-year-old woman, with hypertension and non-insulin dependent diabetes, was referred to our center for a sudden loss of vision in the right eye to hand motions. Ophthalmic examination revealed only right papilledema. Brain magnetic resonance imaging was normal. Laboratory examination revealed no signs of inflammation. A right non-arteritic acute anterior ischemic optic neuropathy was first suspected. One week later, the visual acuity (VA) in the left eye dropped from 10/10 to 5/10 with the appearance of papilledema on fundoscopic exam. This bilaterality led us to begin intravenous corticosteroids followed by transition to oral. This improved the left eye VA to 10/10. Numerous bilateral white patches in the posterior pole appeared secondarily, hypofluorescent in the intermediate and late phases of angiography. RESULTS: The research of the etiology of uveitis showed a positive tuberculin skin test without any prior vaccination. The vitreous humor sample was negative on direct examination, by culture and by polymerase chain reaction (PCR). DISCUSSION: Systemic corticosteroid therapy for ocular tuberculosis is not well described. It may theoretically treat the inflammatory portion of the lesions due to type IV hypersensitivity reaction as in meningeal and pericardial involvement. CONCLUSION: The clinical spectrum of ocular tuberculosis is wide and the diagnosis should be considered in any intraocular inflammatory condition of a chronic or acute recurrent nature, whether or not responsive to steroids.

Lagrangian model of copepod dynamics: Clustering by escape jumps in turbulence.

Planktonic copepods are small crustaceans that have the ability to swim by quick powerful jumps. Such an aptness is used to escape from high shear regions, which may be caused either by flow perturbations, produced by a large predator (i.e., fish larvae), or by the inherent highly turbulent dynamics of the ocean. Through a combined experimental and numerical study, we investigate the impact of jumping behavior on the small-scale patchiness of copepods in a turbulent environment. Recorded velocity tracks of copepods displaying escape response jumps in still water are here used to define and tune a Lagrangian copepod (LC) model. The model is further employed to simulate the behavior of thousands of copepods in a fully developed hydrodynamic turbulent flow obtained by direct numerical simulation of the Navier-Stokes equations. First, we show that the LC velocity statistics is in qualitative agreement with available experimental observations of copepods in turbulence. Second, we quantify the clustering of LC, via the fractal dimension D_{2}. We show that D_{2} can be as low as ∼2.3 and that it critically depends on the shear-rate sensitivity of the proposed LC model, in particular it exhibits a minimum in a narrow range of shear-rate values. We further investigate the effect of jump intensity, jump orientation, and geometrical aspect ratio of the copepods on the small-scale spatial distribution. At last, possible ecological implications of the observed clustering on encounter rates and mating success are discussed.

Multifractal anisotropic swimming: the optimal foraging behaviour of grouper larvae.

It was hypothesized that the Malabar grouper Ephinephelus malabaricus larvae have developed search patterns adapted to the distribution of their prey to maximise their net energy intake per unit time. Analysis of the swimming behaviour of E. malabaricus larvae in both the presence and absence of Artemia sp. nauplii is presented to test this hypothesis. A method derived from turbulence studies (the moment function of the displacements) was used to characterize the behaviour. The results revealed that larval swimming pattern was multifractal (intermittent and long-range-correlated) and isotropic (i.e. uniform in all directions) in the presence of prey, but multifractal and anisotropic (i.e. more frequent long displacement on the vertical axis) in the absence of prey. It is suggested that the search behaviour observed in the absence of prey is an adaptive response to prey distribution pattern, which is often characterised by multifractality and anisotropy (i.e. larger patches on the horizontal axes). In the presence of prey, E. malabaricus shifted to intensive search behaviour. Other possible contributors to the observed patterns are discussed. It is concluded that multifractality and anisotropy of swimming patterns observed in the experiment are mainly explained in an optimal foraging theory framework.

Role of kairomones in host location of the pennellid copepod parasite, Lernaeocera branchialis (L. 1767).

The life cycle of the parasitic copepod Lernaeocera branchialis involves 2 hosts, typically a pleuronectiform host upon which development of larvae and mating of adults occurs and a subsequent gadoid host, upon which the adult female feeds and reproduces. Both the copepodid and adult female stages must therefore locate and identify a suitable host to continue the life cycle. Several mechanisms are potentially involved in locating a host and ensuring its suitability for infection. These may include mechano-reception to detect host movement and chemo-reception to recognize host-associated chemical cues, or kairomones. The aim of this study was to identify the role of kairomones in host location by adult L. branchialis, by analysing their behaviour in response to fish-derived chemicals. Experiments demonstrated that water conditioned by immersion of whiting, Merlangius merlangus, elicited host-seeking behaviour in L. branchialis, whereas cod- (Gadus morhua) conditioned water did not. Lernaeocera branchialis are considered a genetically homogeneous population infecting a range of gadoids. However, their differential response to whiting- and cod-derived chemicals in this study suggests that either there are genetically determined subspecies of L. branchialis or there is some form of environmental pre-conditioning that allows the parasite to preferentially recognize the host species from which it originated.

Tidal influence on the distribution of hydrophobic organic contaminants in the Seine Estuary and biomarker responses on the copepod Eurytemora affinis.

To elucidate tidally related variations of hydrophobic organic contaminant (HOC) bioavailability and the impact of these contaminants on estuarine ecosystems, both PCB and PAH concentrations were investigated in the dissolved phase and in the suspended particulate material (SPM) of the Seine Estuary. Both PAH and PCB highest levels were observed in surface and bottom water when SPM remobilizations were maximum, in relation to higher speed currents. In parallel, acetylcholinesterase (AChE) and glutathione-S-transferase (GST) activities were investigated in the copepod Eurytemora affinis. Significant decreasing AChE levels were measured during the tidal cycle and between surface and bottom copepods related to salinity and to HOC concentration variations. Significant increasing GST levels were also observed when HOC concentrations in the water column were the highest. This study underlined the need to standardize sampling procedures for biomonitoring studies in order to avoid interfering factors that could modify biomarker responses to chemical exposure.

Seasonal variations of hydrophobic organic contaminant concentrations in the water-column of the Seine Estuary and their transfer to a planktonic species Eurytemora affinis (Calanoïda, copepoda). Part 1: PCBs and PAHs.

Hydrophobic organic contaminants (HOC) (i.e. PAHs and PCBs) were measured in the water column and in Eurytemora affinis samples from the Seine Estuary collected from November 2002 to February 2005. Results showed seasonal variations of both total PCB and PAH levels in the suspended particulate matter (SPM) and in the copepods with maximum levels during winter times. PAH and PCB concentrations in the SPM ranged from 499 to 5819ngg(-1) and from 58 to 463ngg(-1), respectively. Phenanthrene, pyrene and benzo[b+j+k]fluoranthene (B[b+j+k]F) were the predominant PAH compounds in the water column, while CB 101, 118, 153 and 138 were the most abundant PCB congeners. PCBs and PAHs bioaccumulated by E. affinis (EA) varied between 383 and 1785ngg(-1) and 165-3866ngg(-1). CB101, 153, 138 and B[b+j+k] were, respectively, the major compounds of PCB and PAH fingerprints in EA. Thereby, the copepods could reach high accumulation factor (ACF) (91000 for PCBs and 17000 for PAHs). The principal component analyses of contaminant concentrations and environmental parameter datasets distinguished two groups of copepods. The winter time cluster, with high percentage of adult copepods, which bioaccumulated the highest PCB and PAH body-burdens, and the second cluster with juveniles showing the lowest HOC concentrations. Thus, PAH and PCB concentrations in EA exhibited significant correlations with the percentage of adults making up the samples.

Seasonal variation of hydrophobic organic contaminant concentrations in the water-column of the Seine Estuary and their transfer to a planktonic species Eurytemora affinis (Calanoïd, copepod). Part 2: Alkylphenol-polyethoxylates.

The occurrence and fate of alkylphenols in various matrices of the Seine River Estuary were studied. Nonylylphenols (NP) and nonylphenol polethoxylates (NPEs) were monitored in surface dissolved water, suspended particulate matter (SPM) and in a copepod, Eurytemora affinis from November 2002 to January 2004. NPs, nonylphenol mono and diethoxylates (NP1EO, NP2EO) and nonylphenol-ethoxy-acetic-acid (NP1EC) were detected and measured in all dissolved water and SPM samples whereas nonylphenoxy-acetic-acid (NP2EC) was only found sporadically in dissolved water samples. Seasonal variation of total concentrations of NPs and NPEs, ranging, respectively from 399 to 2214ngl(-1) and from 405 to 9636ngg(-1), were measured in the dissolved water and in the SPM. Significant decreases were observed in the water-column during the maximum biological activity periods in spring and autumn. Furthermore, increasing levels were observed in the SPM during the winter period. High concentrations of NP1EO and NP were detected in all copepod samples, ranging from 3423 to 6406ngg(-1). This study is the first to report high levels of endocrine disruptors in estuarine copepods.

Effects of salinity and temperature on the expression of enzymatic biomarkers in Eurytemora affinis (Calanoida, Copepoda).

In order to establish effective enzymatic biomarkers that could provide in situ early warning of contaminant exposure in estuarine ecosystems, the potential effects of the principal abiotic factors (temperature and salinity) were investigated on common biomarkers, the acetylcholinesterase (AChE) and the glutathione S-transferase (GST) in Eurytemora affinis. Short term salinity stress effects simulated during an experimental tide indicated that enzymatic activities of this species are characterized by maximum expression related to an optimal salinity range (between 5 and 15 psu). Moreover, longer time exposure to various salinity tanks confirmed the effects of this factor on both AChE and GST activities. Therefore, optimal AChE activity was measured at 10 psu, while optimal GST activity was measured at 5 psu. Furthermore, significant effects of temperature were also recorded, particularly for AChE expression (slight effects were measured on GST expression) with an optimal condition at 11 degrees C. These experiments indicated a more pronounced effect of salinity over temperature especially on the AChE expression and confirmed the need to standardize sampling procedures in relation with environmental parameters for biomonitoring studies based on enzymatic analyses.

Insulin secretion and sensitivity in children on cyclic total parenteral nutrition.

BACKGROUND: Some children receiving total parenteral nutrition (TPN) have abnormal glucose tolerance. METHODS: Insulin secretion and sensitivity were studied in 12 patients, aged 5.7 to 19.4 years, receiving cyclic nocturnal TPN. Insulin secretion was measured during an IV glucose tolerance test (IVGTT; 0.5 g/kg) followed by a hyperglycemic clamp (plasma glucose at 10 mmol/L). Insulin sensitivity was assessed by hyperinsulinemic euglycemic clamp (insulin infusion = 1 mU/kg/min). RESULTS: Patients with normal glucose tolerance receiving TPN had an insulin response to IVGTT similar to that of normal children of the same age. Insulin levels of TPN patients were higher than those in healthy young adults during the hyperglycemic clamp. Whole body glucose disposal was greater in younger than in older children (range, 7.1 to 25.2 mg/kg/min), and this inverse correlation with age was statistically significant (p < .01). Two patients with abnormal glucose tolerance showed a decreased capacity to release insulin, whereas insulin sensitivity was unchanged in one of these two patients. Two patients treated with prednisone or octreotide had insulin levels similar to those of normal TPN children. CONCLUSIONS: The insulin response to sustained hyperglycemia was stronger in children with normal glucose tolerance on cyclic TPN. Patients with a limited capacity to release insulin, either constitutional or acquired, may not be able to produce enough insulin in these conditions and develop glucose intolerance during TPN. Insulin sensitivity was not a key factor in the alteration of glucose tolerance.

Insulin resistance and excess weight in adolescent insulin-dependent diabetic girls.

Insulin dependent diabetic adolescent girls show a tendency towards excess weight. The relationship between insulin resistance and body mass index (BMI) was investigated in 23 Type 1 adolescents aged 13-20 yr. These patients body mass indexes spanned from 19.8 to 30.5. Excess weight was evaluated using Z-scores, corrected for age with reference to french standards. 9 patients with a Z-score greater than 2 were considered as obese. Insulin sensibility was measured using the hyperinsulinaemic euglycaemic clamp (insulin infusion rate, 1 mU kg-1 min-1). The mean glucose infusion rate during the clamp was low in the diabetic girls (2.29 +/- 1.35 mg kg-1 min-1), confirming the existence of insulin resistance. However, the degree of insulin resistance was not correlated with the excess in weight (glucose infusion rate, 2.23 +/- 1.24 vs 2.33 +/- 1.46 mg kg-1 min-1 in the obese and the non-obese patients, respectively). None of the factors which influence on insulin sensitivity could explain this lack of correlation, the obese patients showing greater daily insulin doses (1.36 +/- 0.22 vs 1.22 +/- 0.25 unit kg-1 day-1) and worse metabolic control (Hba1C, 10.9 +/- 1.4 vs 10.2 +/- 2.0%). Insulin resistance was significantly correlated with free fatty acid levels during the clamp.