Anaphylactic reaction to polyethylene‐glycol conjugated‐asparaginase: Premedication and desensitization may not be sufficient

In hypersensitive reactions to native L‐asparaginase, either premedication and desensitization or substitution with polyethylene glycol conjugated asparaginase (PEG‐ASP) is preferred. Anaphylaxis with PEG‐ASP is rare. An 8‐year‐old girl and a 2.5‐year‐old boy, both diagnosed as having acute lymphoblastic leukemia, presented with native L‐asparaginase hypersensitivity and substitution with PEG‐ASP was preferred. They received a premedication (methylprednisolone, hydroxyzine and ranitidine) followed by desensitization with PEG‐ASP infusion. Both patients developed anaphylaxis with peg‐asparaginase. These are the first reported cases of anaphylactic reaction to PEG‐ASP, despite the application of both premedication and desensitization. Anaphylaxis with PEG‐ASP is very rare and premedication and desensitization protocols may not prevent these hypersensitive reactions.     

Effects of Different Over – the - Counter Whitening Products on the Microhardness,Surface Roughness,Color and Shear Bond Strength of Enamel

ObjectiveThe purpose of this in vitro study was to evaluate the effects of four over-the-counter (OTC) whitening products on the microhardness, surface roughness, color, shear bond strength (SBS) and surface charecteristics of human enamel compared with a product used for dentist-supervised home whitening.Materials and methodsSeventy eight enamel specimens allocated into 6 groups (n=13): 1-Opalescence PF 10% (OP) dentist prescribed home whitening product, 2-Opalescence Go prefilled tray (PT), 3-Opalescence Whitening Toothpaste (WT), 4-Listerine Healthy White whitening mouth rinse (WMR), 5-Cavex Bite&White whitening pen (WP) and 6- no treatment (Con). The microhardness (VHN), surface roughness (Ra) and color of the specimens were measured (T₀). The specimens were then subjected to whitening protocols for 14 days (T₁.) followed by artificial saliva storage for 14 days (T₂). The measurements were repeated at T₁ and T₂. The SBS test was done after the application of 35% phosphoric acid (Scotchbond Universal Etchant), followed by a universal adhesive (G-Premio Bond) and a micro hybrid/universal resin composite (Essentia) into a Teflon tube attached to the enamel surface (p<0.05). Surface morphologies of the enamel surfaces were examined by SEM. p value was set at 0.05ResultsApplication of OP, PT and WP decrased the microhardness of enamel specimens (p<0.05) whereas, no significant changes were seen in the microhardness of enamel specimens treated with WT and WMR (p>0.05). Ra values of enamel specimens increased with the application of OP, PT and WT (p<0.05); whereas no changes were observed after the applications of WMR and WP (p>0.05). OP, PT, WMR, and WP changed the color of the enamel(p<0.05). There were not any significant differences among the SBSs groups, apart from OP applied enamel specimens. OP showed the least SBS values (p=0.001). SEM observations revealed smooth enamel surfaces.ConclusionsThe whitening products affected the microhardness, surface roughness, color of enamel differently. Only OP decreased the SBS of the enamel.     

Calculating small-angle scattering intensity functions from electron-microscopy images

We outline procedures to calculate small-angle scattering (SAS) intensity functions from 2-dimensional electron-microscopy (EM) images. Two types of scattering systems were considered: (a) the sample is a set of particles confined to a plane; or (b) the sample is modelled as parallel, infinitely long cylinders that extend into the image plane. In each case, an EM image is segmented into particle instances and the background, whereby coordinates and morphological parameters are computed and used to calculate the constituents of the SAS-intensity function. We compare our results with experimental SAS data, discuss limitations, both general and case specific, and outline some applications of this method which could potentially complement experimental SAS.

We outline procedures to calculate small-angle scattering (SAS) intensity functions from 2-dimensional electron-microscopy (EM) images for two types of scattering systems.

The structures of nanoparticulate systems are commonly characterized by various forms of electron microscopy (EM) and small-angle scattering (SAS) methods. The size and shape of nanoparticles, as well as their spatial-distribution functions, are of particular interest since they govern their structure–function relationships and thus their nanotechnological prospects.^1–6 EM and SAS data are highly complementary. For example, the former images a specific section of a nanomaterial, while the latter realizes its bulk structure by averaging signals obtained from a larger overall area and depth reflective of the sample thickness and beam size. There exists a high degree of overlap in the length scale that is interrogated by EM and SAS data on the same nanomaterial. Yet, these data are necessarily acquired separately and they are analyzed independently. Nevertheless, if suitably processed, the data from one metrology could be used to reconstruct the other. This could draw out the maximum possible structural information about a nanomaterial, or allow data from both sources to be fused to obtain more accurate insights or even highlight processes that result in discrepancies between data from the two methods.This work presents two case studies in which we calculate SAS data from 2-D EM images where (1) the particles being characterized exist on a plane; (2) the sample being imaged can be modelled as parallel, infinitely long cylinders that extend into the image plane. In both cases, we discuss limitations that result in discrepancies between image-obtained SAS intensities and those obtained experimentally. Despite these limitations, we discuss how this method can be complementary to small-angle scattering measurements, by informing experimental design decisions and aiding in model selection. The second case that we present was partially explored by Worthington and Inouye,⁷ and later Meek and Quantock⁸ as well as Quantock et al.⁹ They studied the interfibril distance of collagen fibres in animal corneas by calculating an interference function from pairwise distances of points obtained from an EM image. Their interference function is related to the structure factor which we include in our calculation of SAS intensities, along with form factors which we additionally compute from images. Grubb et al.¹⁰ studied the effect of the orientation of lamellar stack structures on SAXS patterns. The authors did this by generating synthetic images of arrays of lamellar stacks and simulating SAXS data using the 2-D Fourier transform, where they use the Fourier Slice theorem to obtain a 2-D slice of the 3-D transform.¹¹ Afsari et al.¹² and Kim et al.¹³ outline a procedure for calculating small-angle X-ray scattering (SAXS) data from cryo-EM images. Their work makes use of the fact that averaging the correlation functions of many cryo-EM images is equivalent to the Abel transform of SAXS data. Their work is complementary to ours as both methods can be applied under different circumstances. Our work is relevant in situations where image-processing and computer-vision techniques can be employed to segment single EM images and determine morphological and structural information about the scatterers; theirs is relevant when one has numerous cryo-EM images of the same sample.     

Vein of Galen and sinus thrombosis with bilateral thalamic infarcts in sickle cell anaemia: CT follow-up and angiographic demonstration

A 2-year-old boy with known sickle cell disease presented in acute coma. CT revealed bilateral thalamic infarcts and incomplete sinus thrombosis. Angiography confirmed thrombosis of the straight sinus and vein of Galen.     

The effects of long-term oral administration of L-arginine on the erectile response of rabbits with alloxan-induced diabetes

OBJECTIVE: To investigate the effects of the long-term oral administration of L-arginine on the impaired neurogenic and endothelium-dependent relaxation responses of corpus cavernosum smooth muscle from alloxan-induced diabetic rabbits. MATERIALS AND METHODS: Thirty-two New Zealand white rabbits were used in four groups of eight each. In group 1, the rabbits received no treatment after the induction of diabetes with alloxan hydrochloride given intravenously; in group 2, L-arginine (1 mg/mL) was administered orally after the induction of diabetes; in group 3, 6 U/day of insulin was injected subcutaneously; group 4 was maintained with no treatment (as litter-mate controls) for 8 weeks. Thereafter, the rabbits were killed by exsanguination and the penis removed en bloc. The reactivity of corpus cavernosum strips from the penis was then assessed in organ chambers. RESULTS: Relaxation and contraction responses of corpus cavernosum strips to sodium nitroprusside and potassium chloride, respectively, were similar in all groups. Relaxation responses of corpus cavernosum strips elicited by electrical field stimulation and carbachol from rabbits in group 1 were less than in controls; the responses to carbachol were not significantly impaired in group 2 and 3, whereas responses to electrical field stimulation were impaired in both groups when compared with the control group. CONCLUSION: The impairment of endothelium-dependent and nerve-mediated relaxation by diabetes appears to involve an alteration in nitric oxide/cyclic GMP pathway. Administration of oral L-arginine increased endothelium-dependent relaxation, probably through activating nitric oxide synthase. Additionally, decreasing elevated blood glucose concentration and advanced glycosylation products by insulin treatment protected endothelium-dependent relaxation, whereas neither L-arginine nor insulin treatment restored impaired neurogenic relaxation.     

Ultrastructural changes in pneumocyte type II cells following traumatic brain injury in rats.

OBJECTIVE: We aimed to demonstrate the time-dependent ultrastructural changes in pneumocyte type II cells following brain injury, and to propose an electron microscopic scoring model for the damage. METHODS: Forty Wistar-Albino female rats weighing 170-200 g were used. The rats were allocated into five groups. The first group was the control and the second was the craniotomy without trauma. The others were trauma groups. Weight-drop method was used for achieving head trauma. Samples were obtained from the right and left pulmonary lobes at 2-, 8-, and 24-h intervals after transcardiac perfusion. An electron microscopic scoring model was used to reveal the changes. RESULTS: There were no ultrastructural pathological findings pointing to lung injury in any rat of the control groups. There was intense intracellular oedema in type II pneumocyte and interstitial oedema in the adjacent tissue in trauma groups. Oedema in mitochondria and dilatation in both smooth endoplasmic reticulum and Golgi apparatus was more evident in the 8- and 24-h trauma groups. The chromatin dispersion was disintegrated in the nucleus in all trauma groups. Scores of all trauma groups were significantly different from the controls (P<0.05). All trauma groups were different from each other at significant levels (P<0.05 for each trauma groups). CONCLUSIONS: The data suggested that ultrastructural damage is obvious at 2 h and deteriorates with time. The electron microscopic scoring model worked well in depicting the traumatic changes, which were supported by lipid peroxidation. Further experiments are needed to determine the exact outcome after brain death model.     

Effects of Stamm gastrostomy on gastric emptying rate in rats

AIM: Although frequency of gastroesophageal reflux (GER) increases after gastrostomy, the role of gastric emptying in GER has not been evaluated. In this study, we examined the effects of Stamm gastrostomy on gastric emptying rate in rats and whether Stamm gastrostomy induces GER or not. METHODS: Sprague-Dawley rats were divided into three groups. Stamm gastrostomy was done in the first group (SG). Sham operation was carried out in group 2 and the 3rd group served as control. Gastric emptying was assessed using both liquid and solid meals in each group at postoperative 14th day. For solid meal emptying, after fasting of 16 h, the rats were fed for 3 h and gastric emptying rate was measured at the fifth hour. Methylcellulose was used for emptying of liquids and it was given after the animals were fasted for 16 h and gastric emptying rate was measured 30 min later. Histological evaluation for GER was performed in all groups. RESULTS: GER was observed pathophysiologically in 5 of the 7 rats in SG group. Gastric emptying rates of liquid and solid meals were found to be similar in control, SG or sham groups. CONCLUSION: Surgical gastrostomy does not affect the gastric emptying of solid and liquid meals in rats. Other mechanisms should be considered in the development of GER observed following gastrostomy.