Exudate Flow Research Articles

A robotic venous leg ulcer system reveals the benefits of negative pressure wound therapy in effective fluid handling.

We applied a market-leading, single-use negative pressure wound therapy device to a robotic venous leg ulcer system and compared its fluid handling performance with that of standard of care, superabsorbent and foam dressings and compression therapy. For each tested product, we determined a metrics of retained, residual, evaporated and (potential) leaked fluid shares, for three exudate flow regimes representing different possible clinically relevant scenarios. The single-use negative pressure wound therapy system under investigation emerged as the leading treatment option in the aspects of adequate fluid handling and consistent delivery of therapeutic-level wound-bed pressures. The superabsorbent dressing performed reasonably in fluid handling (resulting in some pooling but no leakage), however, it quickly caused excessive wound-bed pressures due to swelling, after less than a day of simulated use. The foam dressing exhibited the poorest fluid handling performance, that is, pooling in the wound-bed as well as occasional leakage, indicating potential inflammation and peri-wound skin maceration risks under real-world clinical use conditions. These laboratory findings highlight the importance of advanced robotic technology as contemporary means to simulate patient and wound behaviours and inform selection of wound care technologies and products, in ways that are impossible to achieve if relying solely on clinical trials and experience.

Device for Negative Pressure Wound Therapy in Low-Resource Regions: Open-Source Description and Bench Test Evaluation.

Background: Negative (vacuum) pressure therapy promotes wound healing. However, commercially available devices are unaffordable to most potential users in low- and middle-income countries (LMICs), limiting access to many patients who could benefit from this treatment. This study aimed to design and test a cheap and easy-to-build negative pressure device and provide its detailed open-source description, thereby enabling free replication. Methods: the negative pressure device was built using off-the-shelf materials available via e-commerce and was based on a small pump, a pressure transducer, and the simplest Arduino controller with a digital display (total retail cost ≤ 75 US$). The device allows the user to set any therapeutic range of intermittent negative pressure and has two independent safety mechanisms. The performance of the low-cost device was carefully tested on the bench using a phantom wound, producing a realistic exudate flow rate. Results: the device generates the pressure patterns set by the user (25–175 mmHg of vacuum pressure, 0–60 min periods) and can drain exudate flows within the clinical range (up to 1 L/h). Conclusions: a novel, low-cost, easy-to-build negative pressure device for wound healing displays excellent technical performance. The open-source hardware description provided here, which allows for free replication and use in LMICs, will facilitate the application and wider utilization of this therapy to patients.

Adhesive-Free, Stretchable, and Permeable Multiplex Wound Care Platform.

The wound healing process remains a poorly understood biological mechanism. The high morbidity and mortality rates associated with chronic wounds are a critical concern to the health care industry. Although assessments and treatment options exist, these strategies have primarily relied on static wound dressings that do not consider the dynamic physicochemical microenvironment and can often create additional complications through the frequent dressing changing procedure. Inspired by the need for engineering "smart" bandages, this study resulted in a multifaceted approach to developing an adhesive-free, permeable, and multiplex sensor system. The electronic-extracellular matrix (e-ECM) platform is capable of noninvasively monitoring chemical and physical changes in real-time on a flexible, stretchable, and permeable biointegrated platform. The multiplex sensors are constructed atop a soft, thin, and microfibrous substrate of silicone to yield a conformal, adhesive-free, convective, or diffusive wound exudate flow, and passive gas transfer for increased cellular epithelization and unobstructed physical and chemical sensor monitoring at the wound site. This platform emulates the native epidermal mechanics and physical extracellular matrix architecture for intimate bio-integration. The multiple biosensor array can continuously examine inflammatory biomarker such as lactate, glucose, pH, oxygen, and wound temperature that correlates to the wound healing status. Additionally, a heating element was incorporated to maintain the optimal thermal conditions at the wound bed. The e-ECM electrochemical biosensors were tested in vitro, within phosphate-buffered saline, and ex vivo, within wound exudate. The "smart" wound bandage combines biocompatible materials, treatments, and monitoring modalities on a microfibrous platform for complex wound dynamic control and analysis.

Wound coverage by the linen dressing accelerates ulcer healing.

IntroductionChronic ulcers are the main cause of morbidity and mortality, and the incidence of chronic wounds is expected to increase given that people live longer and that there are civil diseases.AimMuch attention in the treatment of wounds concerns a dressing that involves wound cleansing, bacterial balance, exudate management and local tissue in a wound environment. These important elements of the evaluation led to the development of an interactive dressing based entirely on flax raw materials.Material and methodsThe complete dressing for wound coverage was prepared from plant (flax) row products: seedcakes, oil, fiber. The content of bioactive compounds (qualitatively and quantitatively) was tested using chromatographic techniques, and their biological activity during tests on fibroblast cell cultures (NHDF). As a final step the clinical trial were performed.ResultsThe dressings, which help control the microenvironment, combining with exudate using hydrophilic fibre, controlling the flow of exudate from the wound to the dressing were generated. They stimulate the activity in the healing cascade and accelerate the healing process by combining lignocellulose fibre with higher amounts of phenolic compounds, sterols, cannabidiol and unsaturated fatty acids simultaneously with the 3-hydroxybutyrate polymer. All constituents of linen dressing are natural, originate from two types of the engineered flax plant. Pre-clinical data reveal a reasonable reduction in wound size in patients with chronic leg ulcers treated with a linen dressing.ConclusionsFor the first time, a successful application of the innovative interactive linen dressing in the treatment of chronic wounds was noted.

Advanced Wound Dressing for Real-Time pH Monitoring.

The rapid evolution of wearable technologies is giving rise to a strong push for textile chemical sensors design targeting the real-time collection of vital parameters for improved healthcare. Among the most promising applications, monitoring of nonhealing wounds is a scarcely explored medical field that still lacks quantitative tools for the management of the healing process. In this work, a smart bandage is developed for the real-time monitoring of wound pH, which has been reported to correlate with the healing stages, thus potentially giving direct access to the wound status without disturbing the wound bed. The fully textile device is realized by integrating a sensing layer, including the two-terminal pH sensor made of a semiconducting polymer and iridium oxide particles, and an absorbent layer ensuring the delivery of a continuous wound exudate flow across the sensor area. The two-terminal sensor exhibits a reversible response with a sensitivity of (59 ± 4) μA pH–1 in the medically relevant pH range for wound monitoring (pH 6–9), and its performance is not substantially affected either by the presence of the most common chemical interferents or by temperature gradients from 22 to 40 °C. Thanks to the robust sensing mechanism based on potentiometric transduction and the simple device geometry, the fully assembled smart bandage was successfully validated in flow analysis using synthetic wound exudate.

Flexible sensors for real-time monitoring of moisture levels in wound dressings

Few studies have investigated methods to monitor the moisture distribution and filling percentage of dressings during wound management. In this study, a new system allowing moisture monitoring across the wound dressing to be measured is examined. The system is composed of a wound bed model with a fluid injection system to mimic exudate flow, a flexible sensor array and data acquisition software. The sensor is composed of 14 flexible electrode arrays, screen-printed on a flexible support and placed on the top of a wound dressing. The system is used to evaluate the performance of a foam-based dressing model. During constant injection of fluid, the wound dressing absorbed moisture at the wound interface throughout the experiment, and expanded as the fluid spread from the wound bed to the edging areas of the foam. The in-time monitoring by the use of the screen-printed electrodes allowed a mapping of the dressing wet surface and estimation of the foam saturation (filling percentage) based on a simple acquisition method without the need to remove the dressing from the wound bed. The findings of this study propose a non-invasive method to monitor the filling of the wound dressing and consequently, a potential solution for determining the optimal dressing change during wound management without causing irritation or further damage to the periwound skin.

Peritumoral tissue compression is predictive of exudate flux in a rat model of cerebral tumor: an MRI study in an embedded tumor.

MRI estimates of extracellular volume and tumor exudate flux in peritumoral tissue are demonstrated in an experimental model of cerebral tumor. Peritumoral extracellular volume predicted the tumor exudate flux. Eighteen RNU athymic rats were inoculated intracerebrally with U251MG tumor cells and studied with dynamic contrast enhanced MRI (DCE-MRI) approximately 18 days post implantation. Using a model selection paradigm and a novel application of Patlak and Logan plots to DCE-MRI data, the distribution volume (i.e. tissue porosity) in the leaky rim of the tumor and that in the tissue external to the rim (the outer rim) were estimated, as was the tumor exudate flow from the inner rim of the tumor through the outer rim. Distribution volume in the outer rim was approximately half that of the inner adjacent region (p < 1 × 10(-4)). The distribution volume of the outer ring was significantly correlated (R(2) = 0.9) with tumor exudate flow from the inner rim. Thus, peritumoral extracellular volume predicted the rate of tumor exudate flux. One explanation for these data is that perfusion, i.e. the delivery of blood to the tumor, was regulated by the compression of the mostly normal tissue of the tumor rim, and that the tumor exudate flow was limited by tumor perfusion.

Very low dose gamma irradiation stimulates gaseous exchange and carboxylation efficiency, but inhibits vascular sap flow in groundnut (Arachis hypogaea L.)

Purpose: An experiment was carried out to determine the effect of low dose gamma radiation on germination, plant growth, nitrogen and carbon fixation and carbon flow and release characteristics of groundnut.Materials and methods: Dry seeds of groundnut variety Trombay groundnut 37A (TG 37A), a radio mutant type developed by Bhabha Atomic Research Centre (BARC), Mumbai, India, were subjected to the pre-sowing treatment of gamma radiation within low to high dose physiological range, i.e., 0.0, 0.0082, 0.0164. 0.0328, 0.0656, 0.1312, 5, 25, 100, 500 Gray (Gy) from a cobalt source (60Co). Observations were recorded for the radiation effect on percentage germination, vigour, gas exchange attributes such as photosynthetic rate, stomatal conductance and transpiration rate, chlorophyll content, root exudation in terms of 14C release, vascular sap flow rate and activities of rate defining carbon and nitrogen assimilating enzymes such as ribulose-1,5-bisphosphate carboxylase (rubisco) and nitrate reductase (NR).Results: Seed germination was increased by 10–25% at the lower doses up to 5 Gy while the improvement in plant vigour in the same dose range was much higher (22–84%) than the unirradiated control. For radiation exposure above 5 Gy, a dose-dependent decline in germination and plant vigour was measured. No significant effect was observed on the photosynthesis at radiation exposure below 5 Gy but above 5 Gy dose there was a decline in the photosynthetic rate. Stomatal conductance and transpiration rate, however, were only inhibited at a high dose of 500 Gy. Leaf rubisco activity and NR activities remained unaffected at all the investigated doses of gamma irradiation. Mean root exudation and sap flow rate of the irradiated plants, irrespective of the dose, was reduced over the unirradiated control more so in a dose-dependent manner.Conclusions: Results indicated that a very low dose of gamma radiation, in centigray to gray range, did not pose any threat and in fact stimulated metabolic functions in such a way to aid growth and development of groundnut plants. It further showed that the radiation threshold for the gas exchange traits and rubisco activity, which ultimately determine the plant health and yield, were higher than compared to the other metabolic attributes and were well beyond 500 Gy and that the dose range above 500 Gy should be targeted to measure lethal effects of radiation on carbon assimilation attributes in leguminous crops, in general, and groundnut in particular.

Comparative analysis of masticatory apparatus features in neonatal common marmosets (Callithrix jacchus) and cotton‐top tamarins (Saguinus oedipus)

Marmosets are unique among callitrichids in habitually gouging trees with their anterior teeth to stimulate exudate flow. Previous analyses suggest that the masticatory apparatus of adult marmosets displays features facilitating relatively large jaw gapes, but decreased load‐resistance ability relative to closely‐related non‐gouging tamarins. We analyzed masticatory apparatus features of neonatal marmosets and tamarins to determine if the morphological differences observed between adults are present at birth. If marmoset infants show similar morphological divergence as adults, then the early appearance of these features suggest they are potential adaptations for tree gouging at wide gapes.We examined six stillborn common marmosets (Callithrix jacchus) and six cotton‐top tamarins (Saguinus oedipus). We microCT scanned the jaws, quantified fiber architecture of masticatory muscles and estimated symphyseal strength in simulated in vitro loading.We found few differences in mandibular cross‐sectional geometry, symphyseal strength or jaw‐muscle architecture between marmoset and tamarin neonates. Collectively, these findings suggest that at least some of the postnatal changes in the marmoset mandible and jaw‐muscle architecture that facilitate wide gapes, but reduced load‐resisting abilities compared to tamarins, arise from phenotypic plasticity related to gouging at wide gapes.Grant Funding Source: This work was funded by grants from the National Science Foundation (BCS‐0959438; BCS‐0412153).

The functional morphology of the anterior masticatory apparatus in tree‐gouging marmosets (cebidae, primates)

Although all genera of Callitrichinae feed on tree exudates, marmosets (Callithrix and Cebuella) use specialized anterior teeth to gouge holes in trees and actively stimulate exudate flow. Behavioral studies demonstrate that marmosets use large jaw gapes but do not appear to generate large bite forces (relative to maximal ability) during gouging. Nonetheless, the anterior teeth of marmosets likely experience different loads during gouging compared to nongouging platyrrhines. We use histological data from sectioned teeth, μCTs of jaws and teeth, and in vitro tests of symphyseal strength to compare the anterior masticatory apparatus in Callithrix to nongouging tamarins (Saguinus) and other cebids. We test the hypotheses that (1) marmoset anterior teeth are adapted to accommodate relatively high stresses linked to dissipating gouging forces and (2) the mandibular symphysis does not provide increased load resistance ability compared with closely related nongouging platyrrhines. Differences in decussation between Callithrix and Saguinus are greatest in the anterior teeth, suggesting an increased load resistance ability specifically in incisor and canine enamel of Callithrix. Callithrix lower incisor crowns are labiolingually thicker suggesting increased bending resistance in this plane and improved wedging ability compared with Saguinus. Anterior tooth roots are larger relative to symphyseal bone volume in Callithrix. Anterior tooth root surface areas also are larger in marmosets for their symphyseal volume, but it remains unclear whether this relative increase is an adaptation for dissipating dental stresses versus a growth-related byproduct of relatively elongated incisors. Finally, simulated jaw loading suggests a reduced ability to withstand external forces in the Callithrix symphysis. The contrast between increased load resistance ability in the anterior dentition versus relatively reduced symphyseal strength (1) suggests a complex loading environment during gouging, (2) highlights the possibility of distinct loading patterns in the anterior teeth versus the symphysis, and (3) points to a potential mosaic pattern of dentofacial adaptations to tree gouging.

Heterochrony of cranial features associated with wide jaw gapes in common marmosets (Callithrix jacchus)

Marmosets are unique among platyrrhines for habitually gouging trees with their anterior teeth to stimulate exudate flow. We previously demonstrated that marmosets exhibit cranial features that facilitate biting at wide jaw gapes during gouging, as compared to skulls of non‐gouging tamarins. Here we examine the role of heterochronic shifts during the ontogeny of cranial features facilitating wide gapes.Three cranial dimensions associated with wide gapes were measured, as well as three dimensions related to load resistance in ontogenetic series from neonates to adults of marmosets (Callithrix jacchus, N=129) and tamarins (Saguinus fuscicollis, N=135). All specimens were captive individuals housed at Oak Ridge Associated Universities' Colony with known ages at death.Marmosets exhibit a complex pattern of heterochronic shifts in cranial features linked to wide gape throughout ontogeny relative to tamarins. The relatively elongated anteroposterior glenoid, condyle and mandible of marmosets consistently appear peramorphic during ontogeny. Corporal and symphyseal dimensions associated with load resistance consistently appear paedomorphic in marmosets.Results support a hypothesis that the shape differences facilitating wide jaw gapes are the result of multiple heterochronic shifts in ontogenetic trajectories between gouging marmosets and non‐gouging tamarins.Supported by NSF (BCS‐0412153, BCS‐0094666).Grant Funding Source: Supported by NSF (BCS‐0412153, BCS‐0094666)

The morphology of the masticatory apparatus facilitates muscle force production at wide jaw gapes in tree-gouging common marmosets (Callithrix jacchus)

Common marmosets (Callithrix jacchus) generate wide jaw gapes when gouging trees with their anterior teeth to elicit tree exudate flow. Closely related cotton-top tamarins (Saguinus oedipus) do not gouge trees but share similar diets including exudates. Maximizing jaw opening theoretically compromises the bite forces that marmosets can generate during gouging. To investigate how jaw-muscle architecture and craniofacial position impact muscle performance during gouging, we combine skull and jaw-muscle architectural features to model muscle force production across a range of jaw gapes in these two species. We incorporate joint mechanics, resting sarcomere length and muscle architecture estimates from the masseter and temporalis to model muscle excursion, sarcomere length and relative tension as a function of joint angle. Muscle excursion from occlusion to an estimated maximum functional gape of 55 deg. was smaller in all regions of the masseter and temporalis of C. jacchus compared with S. oedipus except the posterior temporalis. As a consequence of reduced muscle excursion distributed over more sarcomeres in series (i.e. longer fibers), sarcomere length operating ranges are smaller in C. jacchus jaw muscles across this range of gapes. This configuration allows C. jacchus to act on a more favorable portion of the length-tension curve at larger gapes and thereby generate relatively greater tension in these muscles compared with S. oedipus. Our results suggest that biting performance during tree gouging in common marmosets is improved by a musculoskeletal configuration that reduces muscle stretch at wide gapes while simultaneously facilitating comparatively large muscle forces at the extremes of jaw opening.

Bioreactor for Application of Subatmospheric Pressure to Three-Dimensional Cell Culture

Vacuum-assisted closure (VAC) negative pressure wound therapy (NPWT) is a highly successful and widely used treatment modality for wound healing, although no apparatus exists to monitor the effects of subatmospheric pressure application in vitro. Such an apparatus is desirable to better understand the biological effects of this therapy and potentially improve upon them. This article describes the development and validation of a novel bioreactor that permits such study. Tissue analogues consisting of 3-dimensional fibroblast-containing fibrin clots were cultured in off-the-shelf disposable cell culture inserts and multi-well plates that were integrated into the bioreactor module. Negative pressure dressings, commercialized for wound therapy, were placed on top of the culture, and subatmospheric pressure was applied to the dressing. Cultures were perfused with media at controlled physiologic wound exudate flow rates. The design of this bioreactor permits observation of the culture using an inverted microscope in brightfield and fluorescence modes and sustained incubation of the system in a 5% carbon dioxide atmosphere. This closed-system mimics the wound micro-environment under VAC NPWT. Matrix compression occurs as the subatmospheric pressure draws the dressing material down. At the contact zone, surface undulations were clearly evident on the fibroblast-containing tissue analogues at 24 h and appeared to correspond to the dressing microstructure. The bioreactor design, consisting of sterilizable machined plastics and disposable labware, can be easily scaled to multiple units. Validation experiments show that cell survival in this system is comparable with that seen in cells grown in static tissue culture. After application of VAC NPWT, cell morphology changed, with cells appearing thicker and with an organized actin cytoskeleton. The development and validation of this new culture system establishes a stable platform for in vitro investigations of subatmospheric pressure application to tissues.

Real-time monitoring of moisture levels in wound dressings in vitro: An experimental study

Retaining an appropriate level of moisture at the interface between a healing wound and an applied dressing is considered to be critical for effective wound healing. Failure to control exudate at this interface can result in maceration or drying out of the wound surface. The ability to control moisture balance at the wound interface is therefore a key aspect of wound dressing performance. To date it has not been possible to monitor in any effective manner the distribution of moisture within dressings or how this varies with time. A new measurement system is presented based on sensors placed at the wound/dressing interface which are capable of monitoring moisture levels in real time. The system comprises a model wound bed and sensor array complete with fluid injection path to mimic exudate flow. Eight monitoring points, situated beneath the test dressing, allow the moisture profile across the complete dressing to be measured both during and after fluid injection. The system has been used to evaluate the performance of four foam dressings, a composite hydrofibre dressing and a film dressing. Stark contrasts in the performance of the wound contact layer were found between the different wound dressing types. The composite hydrofibre dressing retained moisture at the wound interface throughout the experiments while areas of the foam dressing quickly became dry, even during constant injection of fluid. The abundance of sensors allowed a moisture map of the surface of the wound dressing to be constructed, illustrating that the moisture profile was not uniform across several of the dressings tested during absorption and evaporation of liquid. These results raise questions as to how the dressings behave on a wound in vivo and indicate the need for a similar clinical monitoring system for tracking wound moisture levels.

Effect of oral hygiene measures on gingival status clinical and histopathological study

Background: Epidemiological studies have demonstrated a direct correlation between severity of the inflammatory periodontal diseases and plaque mass. Some investigations have corralled the histologic parameters with the clinical manifestation of inflammation such as gingival index and gingival exudate flow rate scores. The aim of this study was to correlate between the histological parameters, the gingival clinical status and gingival exudate flow rate (GEFR) and dental plaque. Materials and methods: Seven dental students precipitated in this study. Experimental gingivitis was induced. GI, PlI and GEFR were scored at day 0, 7, 14, 21 and 28. Buccal biopsy excised on day 0, 7, 14, 21 and 28, stained and inflammatory cells were counted. Results: The results of the cohort study demonstrated an increase in all clinical indices during development of the experimental gingivitis and these tend to decrease following the reinstitution of oral hygiene. This study also showed a strong correlation between the clinical and histological parameters. Conclusion: Microbial plaque initiates inflammatory destructive response in the gingiva. This can be reduced by maintenance of good oral hygiene.

Long-term impacts of stand management on ponderosa pine physiology and bark beetle abundance in northern Arizona: A replicated landscape study

Ponderosa pine ( Pinus ponderosa Dougl. ex Laws.) forests in northern Arizona have degraded due to overgrazing, logging, and fire suppression that accompanied Euro-American settlement in the late 1800s. Overstocked stands of suppressed trees with low structural diversity dominate the landscape. These conditions create high risk of catastrophic fires and insect outbreaks. We investigated long-term effects (8–16 years post-treatment) of thinning and thinning + prescribed burning on ponderosa pine water stress, leaf carbon isotope discrimination and nitrogen concentration, oleoresin exudation flow, phloem thickness, radial growth, and bark beetle abundance relative to unmanaged control stands over 2 years of measurement in 12 stands replicated across the landscape. Predawn water potential in late June, phloem thickness, and basal area increment were lower in unmanaged than managed stands. Oleoresin exudation flow in July was greater in unmanaged and thinned + burned stands than thinned stands, and greater in a warm year than a cooler year. Leaf nitrogen concentration differed between years, but not among treatments. Tree competition and water stress were positively correlated, and tree competition was negatively correlated with radial growth and phloem thickness. Pheromone-baited trap catches of Dendroctonus spp. ( D. brevicomis Leconte pooled with D. frontalis Zimmerman) were higher in unmanaged than managed stands, whereas catches of Ips spp. did not differ among treatments. We conclude that thinning with and without prescribed burning can have long-term effects on ponderosa pine water stress, growth, phloem thickness, resin flow, and bark beetle abundance. Low levels of tree mortality from bark beetles at our study sites suggest remarkable resistance of ponderosa pine in mid-elevation forests in northern Arizona, even at high tree densities.

Alveolar Bone Necrosis and Tooth Exfoliation Following Herpes Zoster Infection: A Review of the Literature and Case Report

Herpes zoster (HZ) presents as a cutaneous vesicular eruption in the area innervated by the affected sensory nerve, usually associated with severe pain. Oral manifestations of HZ appear when the mandibular or maxillary divisions of the trigeminal nerve are affected. This is a case report of a 63-year-old woman with HZ infection with trigeminal nerve involvement that led to a rapid loss of alveolar bone and exfoliation of two teeth. The initial intraoral examination showed redness of the alveolar mucosa and gingiva of the lower right quadrant with multiple well-delimited and painful erosive lesions affecting the attached gingiva around the teeth. Two weeks later, teeth number 27 (lower right canine) and 28 (lower right first premolar) had class III mobility, flow of purulent exudate from the gingival sulcus, and deep pockets (>11 mm). The radiological examination showed advanced alveolar bone loss around both teeth. The prognosis for teeth number 27 and 28 was considered hopeless, and they were extracted. Due to extensive necrosis there was no interdental alveolar bone. The case is presented with a review of clinical data from patients with trigeminal HZ infection associated with osteonecrosis or exfoliation of teeth previously reported in the literature. The mechanisms by which the HZ infection leads to the alveolar bone necrosis are discussed. Extensive osteonecrosis and exfoliation of teeth in the area innervated by the nerve affected by HZ has been reported after HZ infection. Clinicians should be aware of this possible outcome after a trigeminal HZ infection.

Comparative functional analysis of skull morphology of tree-gouging primates.

Many primates habitually feed on tree exudates such as gums and saps. Among these exudate feeders, Cebuella pygmaea, Callithrix spp., Phaner furcifer, and most likely Euoticus elegantulus elicit exudate flow by biting into trees with their anterior dentition. We define this behavior as gouging. Beyond the recent publication by Dumont ([1997] Am J Phys Anthropol 102:187-202), there have been few attempts to address whether any aspect of skull form in gouging primates relates to this specialized feeding behavior. However, many researchers have proposed that tree gouging results in larger bite force, larger internal skull loads, and larger jaw gapes in comparison to other chewing and biting behaviors. If true, then we might expect primate gougers to exhibit skull modifications that provide increased abilities to produce bite forces at the incisors, withstand loads in the skull, and/or generate large gapes for gouging. We develop 13 morphological predictions based on the expectation that gouging involves relatively large jaw forces and/or jaw gapes. We compare skull shapes for P. furcifer to five cheirogaleid taxa, E. elegantulus to six galagid species, and C. jacchus to two tamarin species, so as to assess whether gouging primates exhibit these predicted morphological shapes. Our results show little morphological evidence for increased force-production or load-resistance abilities in the skulls of these gouging primates. Conversely, these gougers tend to have skull shapes that are advantageous for creating large gapes. For example, all three gouging species have significantly lower condylar heights relative to the toothrow at a given mandibular length in comparison with closely related, nongouging taxa. Lowering the height of the condyle relative to the mandibular toothrow should reduce the stretching of the masseters and medial pterygoids during jaw opening, as well as position the mandibular incisors more anteriorly at wide jaw gapes. In other words, the lower incisors will follow a more vertical trajectory during both jaw opening and closing. We predict, based on these findings, that tree-gouging primates do not generate unusually large forces, but that they do use relatively large gapes during gouging. Of course, in vivo data on jaw forces and jaw gapes are required to reliably assess skull functions during gouging.

Horizontal and vertical movement of Pseudomonas fluorescens toward exudate of Macrophomina phaseolina in soil: influence of motility and soil properties

The role of motility and cell surface hydrophobicity in transport and dispersal of Pseudomonas fluorescens strains LAM1-hydrophilic, LAM2-hydrophobic and LAM(NM) (non-motile mutant of LAM2) under different soil conditions was studied. Maximum adhesion was recorded for LAM2 in clay loam (70%), followed by sandy loam (68%) and sandy soil (40%). Vertical migration of P fluorescens isolates in soils was recorded at 5 and 25 cm flow of wafer or M. phaseolina exudate. In all the treatments, LAM1 exhibited maximum migration followed, by LAM2 and LAM(NM). The rate of migration of such isolates was lowered in water irrigated soils compared to those irrigated with M. phaseolina exudate. In sandy soil, cells of LAM1 migrated up to 13 cm in comparison to LAM2 (11 cm) and LAN(NM) (9 cm) at 5 cm flow of fungal exudate. Population of LAM1, LAM2 and LAM(NM) was 5.7, 5.68 and 5.61 log cfu g(-1) soil at 1 cm depth, but it decreased to 2.56, 2.21 and 1.99 log cfu during migration up to 11 cm in sandy soil at 5 cm flow of fungal exudate. Greater motility was observed in sandy soil irrigated with water or fungal exudate, followed by sandy loam and clay loam. In general, filtration coefficient (lambda) of P. fluorescens was higher in soils irrigated with 5 cm of water or exudate than with 25 cm of irrigation. The horizontal movement of P. fluorescens strains in sandy soil adjusted at different psi m showed marked reduction with decrease in psi m. The non-motile LAN(NM) did not show chemotactic response and migrated up to a maximum of 3 mm in saturated soils (0 kPa). After 96 h, LAM1 and LAM2 migrated upto 35 and 29 mm respectively in sandy soil. Motile isolates had significantly greater colonization of M. phaseolina sclerotia over the non-motile mutant.

The mid-pericarp cell layer in soybean pod walls is a multicellular compartment enriched in specific lipoxygenase isoforms.

Specific lipoxygenase isoforms immunolocalize to the cytosol of a single cell layer in the soybean (Glycine max L.) pod wall. The cells of this layer, termed the mid-pericarp layer (MPL), are larger than adjacent cells and are highly branched. The entire MPL appears to form an elaborate interdigitated network within the pod wall. A particularly striking feature of the MPL is the presence of extensive regions of very thin, approximately 30 nm, cell wall, which connect the cells of the MPL. It was demonstrated that after mechanical wounding of the pod wall, 40-kD fluorescein-dextran was able to move throughout the MPL. In addition, when pod walls are cut, an exudate flows from the MPL that is highly enriched in lipoxygenase isoforms (approximately 40% of the total protein). The MPL of soybean pod walls may represent a novel multicellular compartment involved in defense of leguminous plants.