Variability in the Spatial Structure of the Central Loop in Cobra Cytotoxins Revealed by X-ray Analysis and Molecular Modeling

Cobra cytotoxins (CTs) belong to the three-fingered protein family and possess membrane activity. Here, we studied cytotoxin 13 from Naja naja cobra venom (CT13Nn). For the first time, a spatial model of CT13Nn with both “water” and “membrane” conformations of the central loop (loop-2) were determined by X-ray crystallography. The “water” conformation of the loop was frequently observed. It was similar to the structure of loop-2 of numerous CTs, determined by either NMR spectroscopy in aqueous solution, or the X-ray method. The “membrane” conformation is rare one and, to date has only been observed by NMR for a single cytotoxin 1 from N. oxiana (CT1No) in detergent micelle. Both CT13Nn and CT1No are S-type CTs. Membrane-binding of these CTs probably involves an additional step—the conformational transformation of the loop-2. To confirm this suggestion, we conducted molecular dynamics simulations of both CT1No and CT13Nn in the Highly Mimetic Membrane Model of palmitoiloleoylphosphatidylglycerol, starting with their “water” NMR models. We found that the both toxins transform their “water” conformation of loop-2 into the “membrane” one during the insertion process. This supports the hypothesis that the S-type CTs, unlike their P-type counterparts, require conformational adaptation of loop-2 during interaction with lipid membranes.     

In Memoriam

This paper summarizes the results on the epidemiology and molecular basis of thalassemias and other hemoglobinopathies in the Republic of Macedonia. Over the past 40 years, population surveys of more than 22,000 participants (school children and workers) from all over the country, have shown that the average incidence of β-thalassemia (thal) trait is 2.6%, ranging from less than 1% in the northeast to 10% in the south. The frequency of δβ-thal is 0.2%, while the frequency of the Swiss type of hereditary persistence of fetal hemoglobin (HPFH) is 0.3%. Screening of 9,619 newborns has shown that the frequency of α-thal trait is 1.5%, of which α-thal-2 is 1.45% and α-thal-1 is 0.05%. The molecular basis of the different forms of β-thal and other hemoglobinopathies has been completely defined. Among the Macedonians, over 450 β-thal chromosomes have been studied. Fifteen different β-thal mutations have been detected, four of which [IVS-I-110 (G→A), IVS-I-6 (T→C), IVS-I-1 (G→A), codon 39 (C→T)] account for 85% of all β-thal chromosomes. Among the Albanians, 48 β-thal chromosomes have been studied. Eight different mutations have been detected, four of which [codon 39, ?30 (T→A), IVS-I-110, IVS-I-1] account for 85% of all β-thal chromosomes. Four new mutations [?101 (C→A), ?87 (C→G), ?30, polyadenylation signal (poly A) (AATAAA→AATGAA)] have been characterized. Molecular analyses of DNA from over 20 unrelated cases with δβ-thal have shown that this condition is caused by a 13 kb deletion (Sicilian type); in two families a deletion of 18 to 23 kb (Macedonian type of δβ-thal) was discovered. Molecular analyses of α-thal in the Republic of Macedonia have shown the following types of molecular defects: 20.5 kb deletion, 17.5 kb deletion, 3.7 kb deletion, poly A mutation (AATAAA→AATGAA), and Hb Icaria [α142, Term→Lys, TAA→AAA (α2)]. The incidence of abnormal hemoglobins (Hbs) in the Republic of Macedonia is 0.4%. Three different α chain variants among 10 families, seven different β chain variants among 33 families, two γ chain variants in two newborns, one variant with an extended α chain, and Hb Lepore among 105 families, have been observed. Structural analysis of numerous cases with Hb Lepore showed that the variant was of the Washington-Boston type.     

Ultrastructural and Stereological Analysis of Walker 256 Carcinosarcoma Cells at Various Stages of Their Differentiation

Ultrastructural and stereological study of Walker 256 carcinosarcoma cells implanted into the femoral muscle of Wistar rats was performed. Two types of Walker 256 carcinosarcoma cells were distinguished and their ultrastructural analysis was carried out. Five differentiation stages were described for each of the two cell types. Differentiation of carcinosarcoma cells was associated with a decrease of the nucleus/cytoplasm ratio, enlargement of the cell, and hyperplasia of granular cytoplasmic reticulum elements, fixed ribosomes, and mitochondria. Differences in the ultrastructure of the two cell types at similar differentiation stages were detected.     

Uterine artery embolization for symptomatic fibroids with imaging follow up

The aim of this study was to determine the effectiveness of uterine artery embolization (UAE) as a primary treatment method in treatment of symptomatic fibroids, whether there are any preembolization MRI characteristics of fibroid predictive of reduction in volume and assess reduction in uterine and dominant fibroid volumes using ultrasound (US) and MRI. Study was carried out in total of 32 patients aged 25–49 years (mean 40.9 years). Uterine and dominant fibroid volume were determined using US and MRI before UAE, MRI and US at 3 months and US alone at 6 and 12 months post‐UAE, supplemented by clinical evaluation at interval of 3, 6 and 12 months. Procedure was carried out through unilateral femoral puncture using poly vinyl alcohol (PVA) particles 355–500 μm in size. All 32 patients had successful procedures. Overall, 25 patients responded, giving a clinical success rate of 78.12%. Mean reduction in volume of uterus and fibroid was 33 and 59.7% and 48.9 and 75.5% on US at 3 and 12 months respectively, and 33.3 and 58.6% on MRI at 3 months. Volume reduction on US and MRI at 3 months was highly correlative. There was no statistical difference in size reduction in volume of fibroids, which were hypointense or hyperintense on T2‐weighted image (T2WI) on pre‐UAE MRI. Uterine artery embolization leads to good technical success and fibroid volume reduction. Ultrasound alone may be used for follow up of patients post‐UAE. Preprocedure signal characteristics on T2WI are not predictors of volume reduction after UAE.     

Hormone level and metabolism of xenobiotics in rats with various phenotype of resistance to hypoxia

The blood of rats with initially low (LR) and high (HR) resistance to hypoxia was characterized with respect to the levels of testosterone, corticosterone, insulin and the activity of liver monooxygenase system enzymes. In response to the acute hypoxia model induction, the level of corticosterone in LR rats was significantly greater than that in HP rats (179 and 24%, respectively). The increase in the blood corticosterone level was accompanied by an increase in the activity of enzymes involved in the metabolism of xenobiotics. Animals with the high corticosterone level were also characterized by more intensive metabolism of testosterone and erythromycine. The metabolism of these substrates depends on the activity of isoforms of the cytochrome P-450 3A family. The high corticosterone concentrations in the plasma of LR rats, appearing in response to the acute hypoxia, exhibit a pronounced stimulating action upon the enzyme 11 beta-hydroxysteroiddehydrogenase, which is accompanied by a more pronounced increase in the corticosterone concentration in liver tissues as compared to that in HR animals. The higher content of corticosterone in LR rats leads to an increase in the concentration of cytochrome P-450 and stimulates the enzymatic activity of 3A isoforms in the liver tissues.     

A comparative assessment of modern suture materials in stomach resection

Results of stomach resection by Bilrot-II in 30 experimental animals and 369 patients with gastric and duodenal ulcers were analyzed. Gastroenteroanastomoses were created with various sutures: capron, polysorb, titanium clips. Pneumopression, bacteriologic and morphologic examinations of anastomosis, fibroesophagogastroduodeno- and intestinoscopy, peripheral computed electrogastroenterography were used. It was revealed that mechanical suture with titanium clips was the best. Polysorb thread is inferior in tissue reaction to mechanical suture but superior to capron. Use of polysorb reduced rate of complications in immediate postoperative period 4 times. Taking into consideration high cost of suture devices it is reasonable to introduce polysorb in practice of abdominal surgery.     

Tissue reactions to biodegradable suture materials from polyoxyalkanoates

The paper presents data on the materials, methods, and results of a study of tissue responses in the postoperative period to implanted suture threads made of the polymer fatty acid derivatives (polyoxyalkanoates). These suture threads have been shown to have the required strength and meet a number of other requirements for currently available materials.     

Colour duplex Doppler ultrasonography evaluation of non‐vasculogenic male erectile dysfunction: An Indian perspective

We present the study of colour duplex Doppler ultrasonography on Indian patients with non‐vasculogenic erectile dysfunction. Patients with a history suggestive of psychogenic impotence along with a normal clinical response to intracavernosal papaverine were presumed to have non‐vasculogenic erectile dysfunction. In our patients, the incidence of psychogenic impotence was much higher and the mean age of patients presenting with erectile dysfunction was lower as compared to patients from developed countries reported in research. The Doppler flowmetry showed much higher mean peak systolic velocities (PSVs) with a negative correlation between age and PSV. End diastolic velocity, resistive index and acceleration time values conformed to the literature.     

Pulmonary microembolism with particles of synthetic polymer "Polysorb"in the treatment of postpartum endometritis

A case of fatal massive pulmonary microembolism with particles of the synthetic polymer preparation in a female of 26 early after delivery is reported. The case is interpreted as a maternal death of the 1st group due to occasional damage in the process of uterine cavity washing with a suspension of a synthetic polymer preparation polysorb in the treatment of purulent postpartum endometritis.     

Establishing good practices in continuing care: a descriptive study of community nursing services for people with HIV infection

This paper presents findings from a 2-year study of community nursing services for people affected by HIV infection in six health authorities in England The research, commissioned by the Department of Health, England, aimed to identify the main bridges and barriers to effective home nursing care, focusing on discharge co-ordination, district nursing and multi-agency collaboration Using a triangulated, case study approach, the main methods of data collection included non-participant observation, case note analysis, semi-structured staff interviews, a postal questionnaire of district nurses and a series of focus groups with service users Study sites included three cities and surrounding districts in the north west, north and south east of England Findings suggest there is considerable room for improvement in discharge planning and that good practice is not the preserve of specialist units District nurses are shown to be willing providers of the majority of home nursing care to this client group, but there is a need for more focused training, greater use of care co-ordinators and more emotional and managerial support