Membrane depolarization is the initial action of crotoxin on isolated murine skeletal muscle.

Although much is known about the pathogenesis of crotoxin-induced muscle damage, the initial site and action of the toxin is still not clear. In this study we used an electrochromic fluorescent dye, Di-4-ANEPPS, to measure the changes in membrane potential of isolated murine omohyoid muscle to determine if depolarization could be one of the initial effects of crotoxin. Omohyoid isolates were pre-loaded with 1 microM Di-4-ANEPPS, exposed to various crotoxin treatments, and the change in fluorescence was recorded using either a dual-wavelength spectrofluorometer or digital imaging. Spectrofluorometry indicated that crotoxin depolarized isolated omohyoid muscles within 4 min as indicated by an increase in fluorescence to 122% of control values. Crotoxin also induced depolarization of extensor digitorum longus and soleus muscles as indicated by an increase in fluorescence of 140 and 110% of the control, respectively. Fluorescent images obtained from omohyoid muscle preparations exposed to crotoxin and Di-4-ANEPPS revealed localized areas of increased fluorescence, muscle contractions, derangement of myofibrils, and differing sensitivity to crotoxin of different muscle cells. Light microscopy results confirmed this variable disruption of muscle cell integrity and differing sensitivity to crotoxin. An increase in creatine kinase release rates confirmed damage to the plasma membrane. We conclude that plasma membrane depolarization is most likely the earliest indicator of cell damage from crotoxin and is quickly followed by hypercontraction of myofilaments, disruption of the plasma membrane, release of creatine kinase and necrosis.     

Early lens aging is accelerated in subjects with a high risk of ischemic heart disease: an epidemiologic study

Background  

Ischemic heart disease (IHD) is one of the most important causes of mortality and morbidity in the Western world. There is a relationship between aging of the lens of the human eye and cardiovascular disease. The present study was conducted to examine if the risk of ischemic heart disease could be estimated by fluorophotometric assessment of lens aging.     

Female adolescents' perceptions of male partners' pregnancy desire

Our objective was to examine the relationship between pregnancy desire among female adolescents and their perception of desire for pregnancy in their male partners. This is an observational cross-sectional study which examined 92 surveys administered to adolescent women between the ages of 14 to 19 years at two obstetrical care services serving a population from limited socioeconomic backgrounds. Participants were all pregnant or awaiting pregnancy test results. Participants were asked about their levels of pregnancy happiness and desire and their partners' levels of pregnancy happiness and desire. Spearman's correlation coefficient was calculated and discordant pairs were examined with McNemar's test. Logistic regression was utilized to examine the relationship between male and female pregnancy happiness and desire. We found that there was a significant correlation between the adolescents' feelings about pregnancy and their perceptions of their male partners' feelings about pregnancy (0.326; P = .004). McNemar's test indicated that male partners were significantly more likely to be reported to feel positively about the pregnancy than female partners (P = .017). Female adolescents who reported male partners who felt positively about the pregnancy were four times as likely to report having desired their pregnancy now or sooner (odds ratio [OR] = 4.35). We conclude that male partners may impact adolescent pregnancy desire. Further prospective studies are needed and male-focused adolescent pregnancy interventions should be developed.     

Structural characterization and cytotoxic properties of a 4-O-methylglucuronoxylan from castanea sativa. 2. Evidence of a structure-activity relationship

Xylans were purified from delignified holocellulose alkaline extracts of Castanea sativa (Spanish chestnut) and Argania spinosa (Argan tree) and their structures analyzed by means of GC of their per-trimethylsilylated methylglycoside derivatives and (1)H NMR spectroscopy. The structures deduced were characteristic of a 4-O-methylglucuronoxylan (MGX) and a homoxylan (HX), respectively, with degrees of polymerization ranging from 182 to 360. In the case of MGX, the regular or random distribution of 4-O-methylglucuronic acid along the xylosyl backbone--determined by MALDI mass spectrometry after autohydrolysis of the polysaccharide--varied and depended both on the botanical source from which they were extracted and on the xylan extraction procedure. The MGX also inhibited in different ways the proliferation as well as the migration and invasion capability of A431 human epidermoid carcinoma cells. These biological properties could be correlated with structural features including values of the degree of polymerization, 4-O-MeGlcA to xylose ratios, and distribution of 4-O-MeGlcA along the xylosyl backbone, giving evidence of a defined structure-activity relationship.     

The relation between bundle branch block and cardiac enlargement

The size of the heart was ascertained at necropsy or by roentgenologic examination in 100 consecutive cases of typical bundle branch block.The clinical diagnoses were: arteriosclerotic heart disease, 58 per cent; coronary artery occlusion, 25 per cent; chronic rheumatic valvular disease, 9 per cent; and miscellaneous conditions, 8 per cent.The heart was enlarged in all cases in which it was examined post mortem; the average cardiac weight was 586 Gm., the lowest, 375 Gm.Of the cases in which there was only a roentgenographic examination, the heart was increased in size in 91 per cent. In three of the six cases in which there was no enlargement, the diagnosis was Graves' disease.Left bundle branch block was present in 90 per cent of the cases. In 71 per cent of these the left ventricle was larger than the right, and in none was the right ventricle preponderant. Hypertensive heart disease was almost invariably associated with left bundle branch block.Of the ten cases of right bundle branch block, the right ventricle was predominant in four, and the left ventricle in one. Both ventricles were enlarged in five cases of coronary artery occlusion.Diffuse myocardial involvement was found in all cases in which a necropsy was performed.It is concluded that, in most instances, chronic bundle branch block is the result of an increase in the size of the heart, and of myocardial damage, with diffuse involvement of the bundle branch system. The type of bundle branch block depends on which ventricle is predominantly enlarged.     

Brief Report: Dynamic calcium signals mediate the feeding response of the carnivorous sundew plant

Some of the most spectacular examples of botanical carnivory—in which predator plants catch and digest animals presumably to supplement the nutrient-poor soils in which they grow—occur within the Droseraceae family. For example, sundews of the genus Drosera have evolved leaf movements and enzyme secretion to facilitate prey digestion. The molecular underpinnings of this behavior remain largely unknown; however, evidence suggests that prey-induced electrical impulses are correlated with movement and production of the defense hormone jasmonic acid (JA), which may alter gene expression. In noncarnivorous plants, JA is linked to electrical activity via changes in cytoplasmic Ca²⁺. Here, we find that dynamic Ca²⁺ changes also occur in sundew (Drosera spatulata) leaves responding to prey-associated mechanical and chemical stimuli. Furthermore, inhibition of these Ca²⁺ changes reduced expression of JA target genes and leaf movements following chemical feeding. Our results are consistent with the presence of a conserved Ca²⁺-dependent JA signaling pathway in the sundew feeding response and provide further credence to the defensive origin of plant carnivory.     

Exploring the Utility of Recombinant Snake Venom Serine Protease Toxins as Immunogens for Generating Experimental Snakebite Antivenoms

Snakebite is a neglected tropical disease that causes high rates of global mortality and morbidity. Although snakebite can cause a variety of pathologies in victims, haemotoxic effects are particularly common and are typically characterised by haemorrhage and/or venom-induced consumption coagulopathy. Despite polyclonal antibody-based antivenoms being the mainstay life-saving therapy for snakebite, they are associated with limited cross-snake species efficacy, as there is often extensive toxin variation between snake venoms, including those used as immunogens for antivenom production. This restricts the therapeutic utility of any antivenom to certain geographical regions. In this study, we explored the feasibility of using recombinantly expressed toxins as immunogens to stimulate focused, pathology-specific, antibodies in order to broadly counteract specific toxins associated with snakebite envenoming. Three snake venom serine proteases (SVSP) toxins, sourced from geographically diverse and medically important viper snake venoms, were successfully expressed in HEK293F mammalian cells and used for murine immunisation. Analyses of the resulting antibody responses revealed that ancrod and RVV-V stimulated the strongest immune responses, and that experimental antivenoms directed against these recombinant SVSP toxins, and a mixture of the three different immunogens, extensively recognised and exhibited immunological binding towards a variety of native snake venoms. While the experimental antivenoms showed some reduction in abnormal clotting parameters stimulated by the toxin immunogens and crude venom, specifically reducing the depletion of fibrinogen levels and prolongation of prothrombin times, fibrinogen degradation experiments revealed that they broadly protected against venom- and toxin-induced fibrinogenolytic functional activities. Overall, our findings further strengthen the case for the use of recombinant venom toxins as supplemental immunogens to stimulate focused and desirable antibody responses capable of neutralising venom-induced pathological effects, and therefore potentially circumventing some of the limitations associated with current snakebite therapies.