Tetrahymena extract protects Paramecium from oxygen-free radicals

Cells of Paramecium tetraurelia will age and die, while cells of Tetrahymena thermophilia are immortal. Both are free-living, ciliated protozoa. Whole cells and homogenates of both Paramecium and Tetrahymena were treated with iron(+2) to induce peroxidation of membrane lipids and other cellular constituents. Paramecium is far more susceptible to such peroxidative damage than Tetrahymena. Indeed, addition of Tetrahymena extract protects Paramecium from peroxidative damage. Tetrahymena’s protective molecules block the initial attack of oxygen-free radicals on Paramecium constituents. A portion of the protective molecules are high molecular weight and temperature sensitive, but others are of small size. Some of the protective molecules are tightly bound to membranes or cytoskeletal elements pelleted from Tetrahymena sonicates.     

Quantitative proton MR spectroscopic imaging of the human brain

Multislice proton MR spectroscopic images (SI) of the brain were quantitated, using the phantom replacement technique. In 16 normal volunteers, ranging in age from 5 to 74 years, average “whole brain” concentrations of choline (Cho), creatine (Cr), and N-acetylaspartate (NAA) were found to be 2.4 ± 0.4, 7.9 ± 1.3, and 11.8 ± 1.0 (mM, mean ± SD), respectively. These values are in good general agreement with those previously determined by single-voxel localization techniques. Cortical gray matter was found to have lower Cho and NAA levels, compared to those of white matter, corpus callosum, and basal ganglia. Cho was also found to increase significantly with age in several locations. Quantitative multislice proton SI is feasible in the clinical environment, and regional and age-dependent variations occur that must be accounted for when evaluating spectra from pathological conditions.     

Nonrhinologic headache in a tertiary rhinology practice.

OBJECTIVE: Our goal was to determine the etiology of headache in patients who were referred for sinus evaluation but were found to have no evidence of rhinosinusitis on computed tomography (CT) of the sinuses and on endoscopic examination. METHODS: Data were collected prospectively from 100 patients with headache but with normal sinus CT and endoscopic examination. Headache and 20-Item Sino-Nasal Outcomes Test (SNOT-20) scores of patients with the chief complaint of headache and who requested further neurologic evaluation (group I) were compared with the scores of patients who did not list headache as a significant symptom (group II) and with the scores of patients without headache (group III). RESULTS: The most common neurologic diagnosis for group I patients (n = 36) was migraine headaches (58%). These patients also had higher mean SNOT-20 scores (24 +/- 3.3) compared to group II patients with mild headache (14.6 +/- 2.3) or group III patients without headache (12.4 +/- 2.1). CONCLUSION: Migraine was the most common type of headache in patients with normal sinus CT treated for presumed rhinosinusitis as the cause of the headache. Patients with headache as their chief complaint that required further neurologic evaluation had overall higher SNOT-20 scores than nonheadache patients, indicating greater disability of their overall quality of life index.     

Endothelial Vascular Function in Hypertensive Patients After Renin—Angiotensin System Blockad

It is unclear whether single and combined pharmacologic inhibition of the renin-angiotensin-aldosterone system have similar effects on endothelial function and blood pressure (BP). The authors evaluated 63 hypertensive patients divided into 4 groups (hydrochlorothiazide 25 mg/d; irbesartan [IRBE] 150 mg/d; quinapril [QUIN] 20 mg/d; or IRBE 150 mg/d + QUIN 20 mg/d) and 25 healthy normotensive subjects (normal) followed for 12 weeks. Endothelium-dependent dysfunction measured as flow-mediated dilation at Weeks 0 and 12 were: normal, 11.5%±2.4% vs 13.5%±2.0%; hydrochlorothiazide, 7.3%±2.0% vs 12.8%±3.1%; QUIN, 7.2%±2.8% vs 13.2%±2.1%; IRBE, 7.1%±2.8% vs 13.0%±2.9%; and IRBE + QUIN, 7.5%±1.9% vs 12.8%±3.0%. Nitroglycerin-mediated responses were: normal, 26.0%±1.9% vs 24.0%±2.5%; hydrochlorothiazide, 17.0%±2.2% vs 18.3%±2.6%; QUIN, 17.8%±3.2% vs 23.4%±3.0%; IRBE, 16.8%±3.6% vs 24.7%±2.0%; and IRBE + QUIN, 17.3%±3.0% vs 25.1%±2.5%. Antihypertensive therapy restored BP to normal and improved the endothelium-dependent and -independent dysfunction after renin-angiotensin-aldosterone system blockade. In a further finding, the combined effect of angiotensin-converting enzyme inhibition and angiotensin II type 1 receptor blockade was not superior to the action of either of these treatments separately.     

A REPRODUCIBLE MODEL OF CHRONIC REJECTION IN RAT RENAL ALLOGRAFTS

A reproducible animal model is essential for the study of the pathogenesis of chronic rejection. This study investigates: (i) the optimal pre-transplant blood transfusion conditions to induce tolerance in a strongly rejecting rat kidney allograft model (Dark Agouti to Albino-Surgery) and avoiding post-transplant immunosuppression; (ii) the functional and histological changes that occur in long-term surviving kidneys and their similarity to chronic rejection; and (iii) the maintenance of tolerance. Prolonged survival occurred after administration of at least two donor blood transfusions with concomitant cyclosporin A (5 mg/kg per day). The time-span between transfusions appeared to be critical: 4 days was more effective than 2 or 7 days. Ineffective treatment led to death within the first 2 weeks post-transplant with histological evidence of acute graft rejection. Seventy-five per cent of long-term survivors experienced impaired renal function in the first week which improved spontaneously and remained stable in 93% of the surviving animals after 100 days and in 668 after 200 days. The morphology of long-term allografts was extremely variable from minor to extensive tubular atrophy, interstitial fibrosis, glomerular hypertrophy, focal and segmental glomerulosclerosis and vascular changes. Glomerular hypertrophy occurred in uninephrectomized controls and probably denoted a response to uninephrectomy. Glomerulosclerosis increased with time and was absent in controls. Although chronic damage was evident, the rats remained tolerant to fresh donor skin. Replacement of the original kidney allograft with a fresh donor kidney resulted in 70% survival. These second grafts showed less severe renal dysfunction and morphological damage than the original allografts in the long-term follow up.     

Tumor targeting by an aptamer.

Aptamers are small oligonucleotides that are selected to bind tightly and specifically to a target molecule. We sought to determine whether aptamers have potential for in vivo delivery of radioisotopes or cytotoxic agents. METHODS: TTA1, an aptamer to the extracellular matrix protein tenascin-C, was prepared in fluorescent and radiolabeled forms. After in vivo administration, uptake and tumor distribution of Rhodamine Red-X-labeled aptamer was studied by fluorescence microscopy. In glioblastoma (U251) and breast cancer (MDA-MB-435) tumor xenografts, biodistribution and imaging studies were performed using TTA1 radiolabeled with (99m)Tc. Tenascin-C levels and tumor uptake were studied in a variety of additional human tumor xenografts. To assess the effect of radiometal chelate on biodistribution, mercapto-acetyl diglycine (MAG(2)) was compared with diethylenetriaminepentaacetic acid and with MAG(2)-3,400-molecular-weight PEG (PEG(3,400)). RESULTS: Intravenous injection of fluorescent aptamer TTA1 produced bright perivascular fluorescence in a xenografted human tumor within 10 min. In the ensuing 3 h, fluorescence diffused throughout the tumor. Labeled with (99m)Tc, TTA1 displayed rapid blood clearance, a half-life of less than 2 min, and rapid tumor penetration: 6% injected dose (%ID)/g at 10 min. Tumor retention was durable, with 2.7 %ID/g at 60 min and a long-lived phase that stabilized at 1 %ID/g. Rapid tumor uptake and blood clearance yielded a tumor-to-blood ratio of 50 within 3 h. Both renal and hepatic clearance pathways were observed. Using the (99m)Tc-labeled aptamer, images of glioblastoma and breast tumors were obtained by planar scintigraphy. Aptamer uptake, seen in several different human tumors, required the presence of the target protein, human tenascin-C. Modification of the MAG(2) radiometal chelator dramatically altered the uptake and clearance patterns. CONCLUSION: TTA1 is taken up by a variety of solid tumors including breast, glioblastoma, lung, and colon. Rapid uptake by tumors and rapid clearance from the blood and other nontarget tissues enables clear tumor imaging. As synthetic molecules, aptamers are readily modified in a site-specific manner. A variety of aptamer conjugates accumulate in tumors, suggesting imaging and potentially therapeutic applications.