Gender differences in smallholders' socioeconomic networks and acquisition of seed of improved wheat varieties in Ethiopia

Enhancing farmers' access to improved seeds is essential to increase productivity and ensure food security in the Global South. However, for many socially marginalized groups, seed access is constrained by the weak institutions governing the input supply chains and the dissemination of information. Using cross-sectional survey data collected from 1,088 farming households in three major wheat-growing regional states of Ethiopia in 2021, this paper assesses empirically how participation in different socioeconomic institutions by men and women farmers shapes their access to and acquisition of seed of improved wheat varieties. The results show that the seed market in the study area is largely informal, where the recycling of wheat seeds from the previous season is a common practice among both male- and female-headed households. However, a significant difference exists between male- and female-headed households regarding patterns of varietal use, with male farmers growing newer wheat varieties more frequently. Men are also more active than women in local social and economic institutions, and their participation is positively associated with the adoption of new wheat varieties. Thus, strengthening the local social and economic institutions and supporting equitable participation of both male- and female-headed households in these institutions could facilitate the diffusion of quality seeds of improved and recently released wheat varieties in countries where the informal seed system plays a major role in seed acquisition.

Presumed Arterial Gas Embolism After Breath-Hold Diving in Shallow Water

Dive-related injuries are relatively common, but almost exclusively occur in recreational or scuba diving. We report 2 children with acute central nervous system complications after breath-hold diving. A 12-year-old boy presented with unilateral leg weakness and paresthesia after diving beneath the water surface for a distance of ∼25 m. After ascent, he suddenly felt extreme thoracic pain that resolved spontaneously. Neurologic examination revealed right leg weakness and sensory deficits with a sensory level at T5. Spinal MRI revealed a nonenhancing T2-hyperintense lesion in the central cord at the level of T1/T2 suggesting a spinal cord edema. A few weeks later, a 13-year-old girl was admitted with acute dizziness, personality changes, confusion, and headache. Thirty minutes before, she had practiced diving beneath the water surface for a distance of ∼25 m. After stepping out, she felt sudden severe thoracic pain and lost consciousness. Shortly later she reported headache and vertigo, and numbness of the complete left side of her body. Neurologic examination revealed reduced sensibility to all modalities, a positive Romberg test, and vertigo. Cerebral MRI revealed no pathologic findings. Both children experienced a strikingly similar clinical course. The chronology of events strongly suggests that both patients were suffering from arterial gas embolism. This condition has been reported for the first time to occur in children after breath-hold diving beneath the water surface without glossopharyngeal insufflation.

Synergistic apoptosis induction by proteasome and histone deacetylase inhibitors is dependent on protein synthesis

Proteasome inhibitors are able to efficiently induce apoptosis in many tumor cells while leaving quiescent, untransformed cells largely unharmed. Here we investigated the further enhancement of proteasome inhibitor-mediated apoptosis induction in Bcr-Abl positive K562 CML cells by simultaneous treatment with different histone deacetylase inhibitors (HDIs). Combining proteasome and HDIs resulted in rapid hyperacetylation of histone H3 and accumulation of polyubiquitinated proteins and the synergistic induction of apoptosis. Apoptosis induction was associated with caspase 8, 3 and 9 activation, Bid processing, destruction of the mitochondrial membrane potential, cleavage of PARP and lamin B and extensive DNA fragmentation. The pan-caspase inhibitor Z-VAD-FMK and the caspase-8 inhibitor Z-IETD-FMK could inhibit K562 cell apoptosis. Apoptosis was also delayed by overexpression of Bcl-xL, as well as by crmA, a known inhibitor of caspases 1 and 8. Caspase 8 activity could still be detected in the presence of ectopic Bcl-xL, but not in crmA transfected cells. The most striking anti-apoptotic effect though was obtained by the translational inhibitor cycloheximide, which abolished caspase 8 processing, blocked Bid cleavage and maintained the mitochondrial transmembrane potential. Apoptosis by the combination treatment occurred independently from CD95/Fas receptor stimulation. These results demonstrated that transcriptional activation by HDIs combined with proteasome inhibitor mediated posttranslational stabilization of protein(s) results in significantly enhanced CML apoptosis which was striktly dependent on uninterrupted protein synthesis.

Characterization of the distribution of matter in hybrid liver support devices where cells are cultured in a 3-D membrane network or on flat substrata

Bioreactors for liver assist tested on small animal models are generally scaled-up to treat humans by increasing their size to host a given liver cell mass. In this process, liver cell function in different culture devices is often established based on the metabolite concentration difference between the bioreactor inlet and outlet irrespective of how matter distributes in the bioreactor. In this paper, we report our investigation aimed at establishing whether bioreactor design and operating conditions influence the distribution of matter in two bioreactors proposed for liver assist. We investigated a clinical-scale bioreactor where liver cells are cultured around a three-dimensional network of hollow fiber membranes and a laboratory-scale bioreactor with cells adherent on collagen-coated flat substrata. The distribution of matter was characterized under different operating modes and conditions in terms of the bioreactor residence time distribution evaluated by means of tracer experiments and modeled as a cascade of N stirred tanks with the same volume. Under conditions recommended by the manufacturers, matter distributed uniformly in the clinical-scale bioreactor as a result of the intense backmixing (N=1) whereas axial mixing was negligible in the laboratory-scale bioreactor (N=8). Switching from recycle to single-pass operation definitely reduced axial mixing in the clinical-scale bioreactor (N=2). Increasing feed flow rate significantly enhanced axial mixing in the laboratory-scale bioreactor (N=4). The effects of design, operating mode and conditions on matter distribution in bioreactors for liver cell culture suggest that characterization of the distribution of matter is a necessary step in the scale-up of bioreactors for liver assist and when function of liver cells cultured in different bioreactors is evaluated and compared.

Classification of cutaneous malignant melanoma: a reassessment of histopathologic criteria for the distinction of different types

BACKGROUND

Human cutaneous malignant melanoma currently is classified into four principle types: nodular, superficial spreading, lentigo maligna, and acral lentiginous. The criteria for the histopathologic diagnosis of these types are not applied consistently. Nevertheless, the classification has become the foundation of many clinical, histopathologic, epidemiologic, and molecular studies. The results of those studies can have validity only if the classification itself is valid. For this reason, the authors reassessed histopathologic criteria advocated for the distinction of the different types of melanoma and searched for other repeatable constellations of findings that may serve to define distinct subsets of the neoplasm.

METHODS

Nine hundred fifteen melanomas were examined with regard to 72 parameters that are considered to be important for histopathologic diagnosis. The results were analyzed statistically with special attention to findings that have been reported to be characteristic of the four principle types of melanoma.

RESULTS

The histopathologic criteria advocated for the distinction of different types of melanoma were found not to correlate with one another. A logistic regression analysis did not detect any other repeatable constellation of morphologic findings that may reflect a distinct biologic subgroup.

CONCLUSIONS

The validity of the current classification of cutaneous malignant melanoma into four principle types could not be substantiated. Malignant melanoma may present with many different forms, but these forms appear to be part of a continuous spectrum rather than examples of distinct biologic entities.

Capture of anti-(Galalpha1-3Gal) antibodies by immobilized Galalpha1-3Gal oligomers derived from carrageenan

An immobilized Galalpha1-3Gal-bearing affinity ligand was prepared as a possible prophylactic binding site of human anti-(Galalpha1-3Gal) antibodies for the prevention of hyperacute rejection of pig xenografts. lambda-Carrageenan, a natural polysaccharide known to possess alternately alpha1-3 and beta1-4-linked D-galactopyranose sulphate residues, was selectively degraded by acetolysis and subsequently deacetylated to obtain lambda-carrageenan oligosaccharides. The resulting syrup was ultrafiltered to remove higher polymers and chromatographed on Sephadex G-15 to produce a series of sized oligosaccharide fractions. An immuno-dot-blot method was established on the basis of the competition between the lambda-carrageenan oligosaccharides in solution and bovine thyroglobulin (BTG), a glycoprotein known to express the Galalpha1-3Gal marker, as the solid-phase antigen. Increasing amounts of lambda-carrageenan fractions added to normal human plasma resulted in a progressive decrease in Galalpha1-3Gal-specific human IgM and IgG binding to BTG. Complete inhibition of Galalpha1-3Gal-specific human immunoglobulin was attained at concentrations less than 0.6 mg of carbohydrate/ml of human plasma with the more active fractions. These bioactive lambda-carrageenan oligosaccharides were immobilized on hydrazide-modified microporous nylon membranes, yielding capacities between 2.18 and 2.86 mg/ml of membrane. A subsequent decrease in the human anti-(Galalpha1-3Gal) antibody level in normal human plasma was demonstrated and proved with the established immuno-dot-blot procedure.

The chemistry of defense and apparency in the corollas ofNicotiana attenuata

The morphological and chemical characteristics of flowers which attract pollinators present a dilemma for plants; advertising may increase the "apparency" of plants to their predators and some pollinators are also predators. We explore how a self-compatible disturbance species,Nicotiana attenuata, copes with this potential dilemma by examining the changes in emission of chemicals from flowers in response to pollination and herbivory. We propose that chemical changes induced by herbivory and pollination reflect the function of the chemicals in the plant. The emission of a single compound, benzyl acetone (BA, 4-phenyl-2-butanone), by flowers increases dramatically (50x) in the evening, peaking just after dark -a pattern of emission characteristic of moth-pollinated flowers. Pools of BA were found only in the outer lip of the corolla where pollinators come in contact with the flower, and diurnal changes in the size of the corolla pool closely paralleled the amount emitted by intact flowers throughout the day, as determined by headspace sampling. Pollination dramatically decreases both the pools of BA in the corolla and its emission from flowers. Similarly, nicotine, a broadly biocidal defense metabolite and an induced defense in vegetative and reproductive tissues, is also found in the headspace of flowers and is principally localized in the basal parts of the corolla below the attachment of the filaments and the nectar reward. Moreover, the dynamics of the corolla pools of BA and nicotine throughout the day are consistent with their roles in advertisement and defense, respectively. The corolla pools of nicotine are stable throughout the day except during the period of peak BA production and emission when nicotine pools decrease significantly. The coordinated increase in BA emission and decline in nicotine pools are not inexorably linked, because herbivory or mechanical damage to corolla tissue rapidly increases corolla nicotine pools without affecting the increase in BA pools. Similarly, leaf damage results in a slower, systemic increase in corolla nicotine pools during reproductive growth but again does not affect BA pools. Excised flowers emitted BA in a manner similar to that of intact flowers, and excision of a majority of flowers from a plant did not alter the BA emission patterns of the remaining flowers. We conclude that althoughN. attenuata's defensive and advertisement chemistries respond synchronously to some environmental stimuli, the flowers' chemical responses to pollinators and herbivoresare distinct and the differences reflect their ecological roles. We propose that the cost-benefit framework of the optimal defense and apparency theories can be fruitfully applied to the allocation of defense metabolites and floral volatiles that function in pollinator attraction, and that this framework can be readily tested by manipulating the patterns of the emissions of plants in the field.

Far-field cochlear microphonics in man and their relation to cochlear integrity

Far-field cochlear microphonics (CM) in man have been measured as a function of frequency by phase-sensitive detection. CM amplitude, dispersion and input-output functions vary periodically with frequency and exhibit certain frequency windows, where responses are approximately frequency specific, in contrast to the commonly accepted model of basal turn CM generators as main sources. Pathological cochleae show abnormal amplitude and phase functions. The results offer new diagnostic possibilities, because haircell function can be evaluated by a routine non-invasive procedure down to the low frequency speech range.

Frequency-following potentials in man by lock-in technique

Frequency-following responses (FFR) from continuous tone stimulation were investigated by lock-in analysis. The technique is superior to conventional tone-burst stimulation, because it allows continuous registration of the response parameters with sweeping frequency. The scalp recorded FFR consists of at least two components separable from each other by their phase/frequency relationship. The microphonic component that dominates in ipsilateral records shows latencies of about 0.5 msec with negligible dispersion and must therefore originate in the basal cochlear turn. The neural component exhibits considerable dispersion, reflecting the travelling wave delay up to the region of best frequency. These long cochlear time delays are consistent with an apical FFR origin, and brain stem sources of the continuous tone response appear to be questionable. The present FFR analysis technique opens up a very direct and comprehensive way to assess the integrity of the entire inner ear for high frequency basal and low frequency apical cochlear regions as well.