Exploring the protease mediated conformational stability in a trypsin inhibitor from Archidendron ellipticum seeds

A Kunitz proteinase inhibitor from Archidendron ellipticum seeds (AeTI) was purified and complexed with bovine trypsin and chymotrypsin. The stoichiometric stability of AeTI with its interacting proteinases was then investigated using spectrophotometric, size exclusion chromatography (HPLC system), Western blotting and circular dichroism (CD) studies. All the methods were remarkably similar in revealing the preference of trypsin over chymotrypsin by AeTI for complex formation. Both Western blotting as well as spectrophotometry based assays for competition experiments indicated that trypsin displaces chymotrypsin from a previously formed AeTI-chymotrypsin complex. Chemical modification of lysine and arginine by TNBS and CHD treatments, respectively, suggested a lysine as the active site residue and also indicated the presence of a single protease-binding site for AeTI. CD of native AeTI showed a sharp minimum at 200 nm and deconvolution of the CD spectra revealed it to be an unordered protein possessing high beta-sheet content. Complex formation of AeTI with trypsin induces a fractional switchover of its unordered structure towards the beta-sheet fraction but lacked any such conversion in the presence of chymotrypsin. Prolonged exposure of excess trypsin generates conformational modifications both in the secondary and the tertiary structures.

Separation of Am3+ and Eu3+ using an extraction chromatographic resin containing bis(2,4,4-trimethylpentyl)dithiophosphinic acid as the stationary phase

Sorption of Am3+ and Eu3+ onto an extraction chromatographic resin material, prepared by impregnating purified bis(2,4,4-trimethylpentyl)dithiophosphinic acid (commercially available as Cyanex 301) into Chromosorb W, was investigated. Separation factor (S.F. = K(d,Am)/K(d,Eu)) values tend to increase in the presence of complexing agents such as thiocyanate and nitrate. In presence of 1 M NaNO3 in the aqueous phase, a S.F. value of approximately 1000 was obtained. The nature of extracted species was ascertained by carrying out the sorption studies at different aqueous phase pH. A column made from 300 mg of the resin material was used for the separation of Am3+ and Eu3+. A synthetic solution containing 1x10(5) cpm each of Am3+ and Eu3+ when loaded on to the column, >99% Eu was eluted out in 60 mL of 1 M NaNO3 at a pH of 3.2 while Am was eluted out using 5 mL of 1 M HNO3. The performance of the resin material was found to be reasonably good even after three cycles.

Evaluation of calix-crown ionophores for selective separation of radio-cesium from acidic nuclear waste solution

Extraction of Cs-137 from nitric acid was carried out using nitrobenzene solutions of calix-crowns such as calix[4]arene-bis(crown-6) (CC-A), calix[4]arene-bis(benzo crown-6) (CC-B) and calix[4]arene-bis(napthocrown-6) (CC-C). CC-C was found to be superior extractant for Cs(I) as compared to the other two calix-crown ligands used in the present study. The effect of diluent on the extraction of Cs(I) indicated the trend: nitrobenzene>dichloroethane>chloroform>decanol>>carbon tetrachloride approximately n-hexane approximately toluene. Subsequently, the studies were carried out with nitrobenzene solutions of the calix-crown ligands (mainly CC-C) on the effects of (a) aqueous phase acidity, (b) ligand concentration, and (c) cesium concentration on Cs extraction from nitric acid media. Conditions for quantitative extraction and stripping were optimized and the extracted species conformed to {[CsL]+.[NO3]-.nH2O}. Selectivity studies were carried out using an irradiated natural U target involving tracer amount of fission products activities. Extraction of Cs(I) from a synthetic high level waste solution was also carried out. The promising results obtained in the present studies indicate possible use of the calix-crown ligand for Cs(I) recovery from the acidic high level waste.

Demonstration of an expedited breast care (EBC) clinic

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Background: Women report waiting for a breast biopsy result as a time of psychological distress. Waiting also delays entry into definitive oncology care, and patients in underserved communities may be lost to follow up. In this proof-of-concept demonstration, an Expedited Breast Care (EBC) clinic was developed to give patients the opportunity to receive same-day biopsy results. Methods: Patients requiring core breast biopsy at a community hospital were approached sequentially to participate. Following surgical biopsy, tissue underwent ultra-rapid fixation and processing. After paraffin sections were prepared and stained, the glass histopathology slides were imaged with a virtual slide scanner. Digital images were stored on a server and viewed on the Internet by a telepathologist at a tertiary care center. Light microscopy review was concurrently performed as the gold standard. After telepathology review and light microscopy confirmation, patients presented to the telemedicine suite to receive biopsy results. A teleoncologist at the tertiary care center presented all pathology results to the patient, whether benign or malignant. Time and patient satisfaction data were collected. Results: Nine patients have participated. Within 2 hours from the time the tissue arrived at the laboratory, digital images were available to the telepathologist. The teleoncologist presented results to patients within 3–5 hours after the biopsy procedure. Patients reported satisfaction with the same-day service, and stated they would seek EBC again in the event of a future breast biopsy. Many patients expressed relief at receiving results so promptly and felt they had avoided the stress of waiting longer for results. The elapsed time from mammogram to definitive oncology care was shorter for EBC patients compared to a control group of patients at a clinic not offering EBC, although the results did not reach statistical significance (Mann-Whitney U: Z = −1.804, p = 0.0713). Conclusions: These data indicate EBC can be successfully accomplished. Current studies to assess EBC’s role in facilitating prompt entry into definitive oncology care are underway. By incorporating rapid tissue processing with telepathology and teleoncology, EBC can improve access to breast care in underserved areas.

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Inflammatory focal myositis of the sternomastoid muscle: is there an absolute indication for biopsy? A case report and review of the literature

Focal myositis is a localised inflammatory process affecting skeletal muscles belonging to the pathological group of inflammatory pseudo tumours of soft tissue that includes myositis ossificans, proliferative myositis and nodular pseudosarcomatous fasciitis. Very rarely, it may affect one of the neck muscles and present as a neck lump, in which case both the clinical and pathological picture can mimic a sarcoma. We describe a case of focal myositis of the sternocleidomastoid muscle, present a review of this rare condition and debate the necessity of biopsy.

Steroid withdrawal syndrome after successful treatment of Cushing's syndrome: a reminder

Steroid withdrawal syndrome (SWS) usually refers to relapse of the disease being treated after withdrawal of glucocorticoid therapy, or the symptoms of adrenal insufficiency which occur when glucocorticoids are rapidly reduced or stopped. A less well-recognised form of SWS is that which develops when patients experience a symptom complex similar to that of adrenal insufficiency despite acceptable cortisol levels. We describe three patients who presented with this form of SWS following surgical treatment for endogenous Cushing's syndrome. All responded well to a short-term increase in the dose of glucocorticoid replacement therapy, with the median duration of the syndrome being 10 months (range 6-10 months). Trough serum cortisol levels above 100 nmol/l, with peaks between 460 and 750 nmol/l were documented in the first two patients at presentation with SWS. It is thought that the syndrome may result from development of tolerance to glucocorticoids, and mediators considered to be important in its development include interleukin-6, corticotrophin-releasing hormone, vasopressin, and central noradrenergic and dopaminergic systems. The exact underlying mechanism for SWS remains unclear. However, with increasing recommendations for use of lower doses of replacement glucocorticoids, its incidence may increase. Physicians need to be aware of this condition, which is self-limiting and easily treated by a temporary increase in the dose of glucocorticoid replacement therapy. It is possible that a slower glucocorticoid tapering regimen than that used in the standard postoperative management of patients undergoing pituitary surgery may reduce the risk of development of SWS.

New measurement of the cosmic-ray positron fraction from 5 to 15 GeV

We present a new measurement of the cosmic-ray positron fraction at energies between 5 and 15 GeV with the balloon-borne HEAT-pbar instrument in the spring of 2000. The data presented here are compatible with our previous measurements, obtained with a different instrument. The combined data from the three HEAT flights indicate a small positron flux of nonstandard origin above 5 GeV. We compare the new measurement with earlier data obtained with the HEAT-e(+/-) instrument, during the opposite epoch of the solar cycle, and conclude that our measurements do not support predictions of charge sign dependent solar modulation of the positron abundance at 5 GeV.