Protective effect of sucrose on spray drying of oxyhemoglobin

As far as we know, spray drying has previously not been applied to oxyhemoglobin, undoubtedly because of the sensitivity of oxyhemoglobin to temperature and oxidation. Our experience with freeze drying encouraged us to perform spray-drying trials in order to compare the results of the two methods, in the absence and the presence of protective compounds. Spray drying of hemoglobin without a protective compound led, as in freeze drying, to formation of a percentage of methemoglobin (50%) that makes it unsuitable for transporting oxygen. In the presence of 0.25 M sucrose (optimum) and at 80-100 degrees C, the functional properties of the hemoglobin were well preserved (methemoglobin approximately 4%), and the residual humidity was limited to approximately 3%. Structural investigation by optical circular dichroism confirmed the results obtained by freeze drying: in the presence of an effective protector, the spectra were similar to those of control hemoglobin and the immediate environment of the heme did not undergo any major change. Electron spin resonance absorption bands in all samples were similar for each value of the spectral decomposition factor, g. This suggests that the structure of the heme is not altered by desiccation and that the protector does not penetrate into the heme pocket since it would have disturbed the symmetry of the crystalline field. Fundamentally, these results are equivalent or similar to those observed with freeze drying; since spray drying is a different process of dehydration, the results indicate a lack of specificity in the phenomena of oxidation or of protection affecting hemoglobin.     

Effects of various osmolarity on human red blood cells in terms of potassium efflux and hemolysis induced by free radicals

Objectives

To study in an in vitro model of erythrocytes exposed to free radicals the effects of hyperosmolarity and hypoosmolarity on the induced potassium efflux and hemolysis.

Design setting

Erythrocytes were separated from plasma and suspended in 3 different phosphate buffer solutions (HYPO, ISO, and HYPER) containing, respectively, 100, 150 and 200 mmol/l of Na. Free radicals were generated from 2,2′-azobis(2-amidinopropane) hydrochloride (AAPH). Potassium efflux (flame photometry) and hemolysis (Drabkin method) were measured. Measurements were expressed in % (versus total) and area under % versus time curves were calculated (% min). An ANOVA was used for statistical analysis.

Results

In presence of AAPH, hemolysis was significantly greater in HYPO (732.45 ± 40 % min) and lower in HYPER (578.97 ± 15 % min) as compared to ISO (608.30 ± 42 % min). Potassium efflux was significantly increased in HYPER (7508.04 ± 85 % min) as compared with HYPO (5308.74 ± 62 % min) and ISO (6561.39 ± 62 % min).

Discussion

Our data suggest that hyperosmolarity increases the resistance of the red blood cells when exposed to free radicals as shown by the decreased hemolysis. In such conditions, the potassium efflux analysis appears to be inappropriate to evaluate the free radical effects on erythrocytes.     

Accuracy of urine output measurement with regular disposable nappies

Evaporation of urine from four types of disposable absorbent infant nappies (A, B, C, D) was assessed under a radiant warmer or in an incubator, with or without phototherapy. Each nappy was weighed dry and then 5, 10, 15 or 30 ml of urine were added. The nappy was immediately reweighed, placed in its study environment and then weighed 5, 15, 30, 60 and 120 min later. Unter all conditions, the percentage evaporation from each type of nappy increased during the 120 min and was inversely correlated with urine volume. Without phototherapy, the maximum evaporation at 120 min with a 5-ml urine sample was 15.9%±6.1% for nappy B in the incubator and 20.8%±4.0% for nappy A in the radiant warmer. Phototherapy was associated with slight but significant changes in evaporation in the incubator and the radiant warmer. Nappy D allowed the lowest percentage evaporation in the incubator with or without phototherapy and in the radiant warmer with phototherapy (8.8%±4.4%, 2.4%±1.8% and 16.0%±10%, respectively for a 5-ml urine sample).     

In vitro and in vivo antimalarial activity of derivatives of 1,10-phenanthroline framework

A series of trisubstituted 1,10-phenanthrolines was prepared. These compounds exhibited mild to high biological activities in vitro both toward chloroquino-resistant FcB1-Columbia and FcM29-Cameron strains and Nigerian chloroquino-sensitive strain of Plasmodium falciparum. Cytotoxicity of the most active compounds was estimated showing that one compound (10) exhibited a selective activity against malaria parasite (selectivity indexes of 52 and 144). Antiplasmodial activity of this derivative was optimized by N-10 alkylation and the phenanthrolinium salt (15) submitted to an in vivo study using mice infected by P. vinckei petteri showing an ED50 of 7.86 mg/kg/day.     

Caracteres de l'inhibition de la glutamate,de l'isocitrate et de l'alcool deshydrogenases par les analogues formique,acetique et proprionique de la triiodo-3,5,3'-l-thyronine

3,5,3'-Triiodo-thyroformic (TF₃), 3,5,3'-triiodo-thyroacetic (TA₃) and 3,5,3'-triiodo-thyropropionic (TP₃) acids, which are structural analogs of 3,5,3'-triiodo-L-thyronine (LT₃), have been found to inhibit beef liver glutamate dehydrogenase (GlDH), horse liver alcohol dehydrogenase (ADH) and pig heart isocitrate dehydrogenase (ICDH), but different mechanisms are involved. TF₃, TA₃ and TP₃ inhibit GlDH non competitively with respect to NADP, but competitively with ADP-ribose, an activator of GlDH. For the inhibition of ADH, the three iodinated derivatives compete with NAD and ADP-ribose; ADP-ribose being itself competitive with NAD. So, it appears that TF₃, TA₃ and TP₃ interfere with the coenzyme binding by blocking the binding site of the ADP-ribose portion of the coenzyme. These iodinated inhibitors quench the enhanced fluorescence which originates from the enzyme-coenzyme binding. However, in the case of the GlDH, TP₃ exhibit an opposite effect. E.s.r. studies showed that ICDH inhibition by TA₃, did not result from the chelation of Mn²⁺, but that TA₃ impaired binding of Mn²⁺ to the enzyme and coenzyme.     

Detection of residual packets in cocaine body packers: low accuracy of abdominal radiography—a prospective study

Objective

To evaluate the accuracy of abdominal radiography (AXR) for the detection of residual cocaine packets by comparison with computed tomography (CT).

Methods

Over a 1-year period unenhanced CT was systematically performed in addition to AXR for pre-discharge evaluation of cocaine body packers. AXR and CT were interpreted independently by two radiologists blinded to clinical outcome. Patient and packet characteristics were compared between the groups with residual portage and complete decontamination.

Results

Among 138 body packers studied, 14 (10 %) had one residual packet identified on pre-discharge CT. On AXR, at least one reader failed to detect the residual packet in 10 (70 %) of these 14 body packers. The sensitivity and specificity of AXR were 28.6 % (95 % CI: 8.4–58.1) and 100.0 % (95 % CI: 97.0–100.0) for reader 1 and 35.7 % (95 % CI: 12.8–64.9) and 97.6 % (95 % CI: 93.1–99.5) for reader 2. There were no significant patient or packet characteristics predictive of residual portage or AXR false negativity. All positive CT results were confirmed by delayed expulsion or surgical findings, while negative results were confirmed by further surveillance.

Conclusion

Given the poor performance of AXR, CT should be systematically performed to ensure safe hospital discharge of cocaine body packers.

Key Points

? Both abdominal radiography and computed tomography can identify gastrointestinal cocaine packets. ? Ten per cent of body packers had residual packets despite two packet-free stools. ? Seventy per cent of these residual packets were missed on AXR. ? No patient or packet characteristics predicted residual packets or AXR false negativity. ? CT is necessary to ensure safe medical discharge of body packers.     

The medicinal leech Hirudo medicinalis: clinical use of the animal and therapeutic prospects of hirudin

Blood sucking leech, Hirudo medicinalis, used in Medicine for very long, knew an intensive employment during early 18e century but its excess was responsible of the temporary disparition of the animal from the therapeutics. Leech has currently recovered a clinical use, especially in microsurgery. On the other hand, hirudin, main active compound isolated from leech extract and also known and used for long, offers interesting outlooks by its anticoagulant and antithrombic properties. This explains the great interest of hirudin preparation by molecular genetics.     

Hsp70, an immunological actor playing with the intracellular self under oxidative stress

Heat shock proteins (HSPs) have originally been studied at cellular and molecular levels for their role in resistance to stress. More recently, HSPs have received the attention of immunologists for their ability to stimulate the adaptive and innate immune system. However, the immunological consequences mediated by their expression under stress have not been fully explored. Recent studies on the inducible Hsp70 have promoted the emergence of a new link between oxidative stress and immune response. This view is based on the observation that (i) the stress inducible Hsp70, but not the constitutive Hsc70 co-segregates with immunogenicity of tumour cells in vivo , (ii) the stresses that induce Hsp70 expression also give rise to cellular oxidation, and (iii) an active immune response is a source of oxidative stresses. Here, one explores the hypothesis that, under oxidative stress, Hsp70 is more efficient in discriminating intracellular 'non-self polypeptides' than Hsc70, leading to a more efficient stimulation of the immune system.     

Isopropyldiiodothyronine and α-methylthyroxine: Comparison of their in vitro and in vivo effects with those of thyroid hormones

The in vivo and din vitro effects of the two thyroid hormone analogs 3,5-diiodo-3′-isopropyl-L-thyronine (IPT₂) and of α-methyl-DL-thyroxine (MT₄) have been compared to those of the thyroid hormones 3,5,3′-triiodo-L-thyronine (T₃) and thyroxine (T₄).Against purified glutamate, isocitrate and alcohol dehydrogenases IPT₂ and MT₄ exert inhibitory effects which are quite similar to those exerted by T₃ and T₄. The effects of the analogs on isolated mitochondria follow closely those of the hormones i.e. they uncouple phosphorylations and inhibit electron transfer along the respiratory chain.When thyroidectomized animals are treated with analogs (5 nmoles/100 g/day for 15 days) their effects on two accepted parameters of thyromimetic activity, metabolic rate (BMR) and α-glycerophosphate (GPD) induction, are quite different. After IPT₂-treatment, the rise in MR and GPD indicates a hyperthyroid state, whereas MT₄-treatment results in very incomplete compensation of th hypothyroid state. However, treatment of the thyroidectomized animal with IPT₂ or MT₄ has the same effect on hepatic mitochondrial glutamate dehydrogenase as treatment with T₄.A relation between thyroid state and adrenal tyrosine hydroxylase (TH) activity has been established; TH activity which decreases in the thyroidectomized animal, is brought back to normal by administration of T₄ and above normal by that of IPT₂.