Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests.

Implementation of wildfire- and climate-adaptation strategies in seasonally dry forests of western North America is impeded by numerous constraints and uncertainties. After more than a century of resource and land use change, some question the need for proactive management, particularly given novel social, ecological, and climatic conditions. To address this question, we first provide a framework for assessing changes in landscape conditions and fire regimes. Using this framework, we then evaluate evidence of change in contemporary conditions relative to those maintained by active fire regimes, i.e., those uninterrupted by a century or more of human-induced fire exclusion. The cumulative results of more than a century of research document a persistent and substantial fire deficit and widespread alterations to ecological structures and functions. These changes are not necessarily apparent at all spatial scales or in all dimensions of fire regimes and forest and nonforest conditions. Nonetheless, loss of the once abundant influence of low- and moderate-severity fires suggests that even the least fire-prone ecosystems may be affected by alteration of the surrounding landscape and, consequently, ecosystem functions. Vegetation spatial patterns in fire-excluded forested landscapes no longer reflect the heterogeneity maintained by interacting fires of active fire regimes. Live and dead vegetation (surface and canopy fuels) is generally more abundant and continuous than before European colonization. As a result, current conditions are more vulnerable to the direct and indirect effects of seasonal and episodic increases in drought and fire, especially under a rapidly warming climate. Long-term fire exclusion and contemporaneous social-ecological influences continue to extensively modify seasonally dry forested landscapes. Management that realigns or adapts fire-excluded conditions to seasonal and episodic increases in drought and fire can moderate ecosystem transitions as forests and human communities adapt to changing climatic and disturbance regimes. As adaptation strategies are developed, evaluated, and implemented, objective scientific evaluation of ongoing research and monitoring can aid differentiation of warranted and unwarranted uncertainties.

The promise and pitfalls of composite endpoints in sepsis and COVID-19 clinical trials.

Composite endpoints reveal the tendency for statistical convention to arise locally within subfields. Composites are familiar in cardiovascular trials, yet almost unknown in sepsis. However, the VITAMINS trial in patients with septic shock adopted a composite of mortality and vasopressor-free days, and an ordinal scale describing patient status rapidly became standard in COVID studies. Aware that recent use could incite interest in such endpoints, we are motivated to flag their potential value and pitfalls for sepsis research and COVID studies.

Oxyacetylene torch testing and microstructural characterization of tantalum carbide.

Tantalum carbide samples have been subjected to high-temperature testing at ∼2300°C using an oxyacetylene torch to evaluate their potential for ultra-high temperature applications. While large samples cracked during the rapid heating, indicating their inability to withstand thermal shock, small samples survived the severe test conditions. The oxidation products formed were characterized and found to comprise different phases of Ta2 O5 . The ultra-high temperature experienced by the samples resulted in the formation of many interesting microstructures, including the formation of submicron sized grains, which has not been reported previously in the literature, as well as the expected evidence of melting.

The indications for and timing of haemodialysis in critically ill patients with acute kidney injury in Johannesburg, South Africa.

Background: Acute kidney injury (AKI) is common among patients admitted to the intensive care unit (ICU). It is an independent risk factor for morbidity and mortality. The optimal timing of renal replacement therapy (RRT) remains unknown, resulting in a wide variation in observed current practices. There is a paucity of data on current practices within ICUs in South Africa. Objectives: To describe current practices in the timing of RRT in patients with AKI admitted to the ICU. The secondary objectives were to describe the patient characteristics, severity of illness scores, staging at initiation of RRT, outcome at ICU discharge, and to estimate and describe delays in the initiation of RRT. Methods: A retrospective, descriptive study was conducted in an adult academic ICU in Soweto from 1 January 2014 to 31 December 2015. Results: There were 2 152 ICU admissions over the 2 years. Less than a tenth of the patients (3.5%; n=76) required RRT and the majority had sepsis (83%). The most common indication for RRT was oliguria/anuria (50%; n=38), followed by worsening urea/creatinine (29%; n=22), metabolic acidosis (11.8%; n=9), refractory hyperkalaemia (5.3%; n=4), fluid overload (2.6%; n=2) and other (1.3%; n=1). More than half of the patients (55%; n=42) had RRT instituted on admission day (D0 ), while 45% (n=34) had RRT initiated after D0 (D1-21). RRT was initiated at stage 3 AKI in 90% and 94% of D0 RRT group and D1-21 RRT group, respectively. The median (interquartile range (IQR)) time to starting RRT was 4 (4) hours once the decision to initiate RRT was made. The composite outcome of death, RRT dependence and diuretic dependence at ICU discharge was 21% and there was no difference between the two groups (p=0.22). The ICU mortality was 3%. Conclusion: The sampled population was young, predominantly male and had post emergency surgery with a high burden of sepsis and HIV. The observed current threshold for RRT was late (stage 3 AKI with classic/emergent indications) with outcomes comparable with the reviewed literature. Contributions of the study: The present study adds insight into the practice of initiating RRT in patients admitted to the ICU with AKI. These data have previously not been described in the South African context. The patient population differed from the literature in that they were young, predominantly male and had post-emergency surgery with a high burden of sepsis and HIV.

LOPP chemotherapy as a first-line treatment for dogs with T-cell lymphoma.

BACKGROUND: The aim of this study was to describe the use of a lomustine (CCNU), vincristine, procarbazine and prednisolone (LOPP) protocol used for treatment of chemotherapy naive T-cell lymphoma patients and to describe the response rate, toxicity and disease-free interval compared historically to CHOP chemotherapy. MATERIALS AND METHODS: Retrospective case study of 31 dogs with naïve T-cell lymphoma treated with a lomustine (CCNU), vincristine, procarbazine and prednisolone (LOPP) protocol. RESULTS: Thirty-one dogs with T cell lymphoma were treated. The overall response rate was 97%. Of the 30 dogs that had a response to LOPP chemotherapy, the median disease free interval was 176 days (range 0-1745 days). The median overall survival time for this study group was 323 days (range 51-1758 days). All deaths in this study were attributable to lymphoma. CONCLUSION: LOPP chemotherapy for T cell lymphoma is well tolerated with a low toxicity profile and an excellent overall response rate. This protocol showed minimal toxicity and comparable disease free interval and survival times for canine high grade T cell lymphoma treated with CHOP.

Spread of a model invasive alien species, the harlequin ladybird Harmonia axyridis in Britain and Ireland.

Invasive alien species are widely recognized as one of the main threats to global biodiversity. Rapid flow of information on the occurrence of invasive alien species is critical to underpin effective action. Citizen science, i.e. the involvement of volunteers in science, provides an opportunity to improve the information available on invasive alien species. Here we describe the dataset created via a citizen science approach to track the spread of a well-studied invasive alien species, the harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae) in Britain and Ireland. This dataset comprises 48 510 verified and validated spatio-temporal records of the occurrence of H. axyridis in Britain and Ireland, from first arrival in 2003, to the end of 2016. A clear and rapid spread of the species within Britain and Ireland is evident. A major reuse value of the dataset is in modelling the spread of an invasive species and applying this to other potential invasive alien species in order to predict and prevent their further spread.

Negative pressure wound therapy using a portable single-use device for free skin grafts on the distal extremity in seven dogs.

OBJECTIVE: Retrospective study to describe clinical experience with a portable single-use negative pressure wound therapy device after application of full-thickness meshed skin grafts to wounds on the distal extremities of seven dogs. METHODS: Seven dogs were treated with portable NPWT after receiving skin grafts; six as the result of tumour resection and one for traumatic injury. Medical records were reviewed and data recorded on patient signalment, cause and location of wound, surgical technique, application and maintenance of portable NPWT, graft survival and outcome, and complications encountered with the system. CLINICAL OUTCOMES: NPWT was provided for between 4 and 7 days. Five patients were discharged from hospital during the treatment period. Application and maintenance of the portable device was technically easy and no major complications were encountered. Minor complications consisted of fluid accumulation in the evacuation tubing. All dogs achieved 100% graft survival. CONCLUSIONS: Application and maintenance of the portable device was technically straightforward. All dogs receiving portable NPWT after transfer of a free skin graft to the distal extremity had a successful outcome.

Mechanisms of delivery of liposome-encapsulated cytosine arabinoside to CV-1 cells in vitro. Fluorescence-microscopic and cytotoxicity studies.

Fluorescence microscopy and assays of the cytotoxicity of liposome-encapsulated cytosine arabinoside (araC) have been used to examine the interactions of CV-1 cells with pH-sensitive liposomes, combining phosphatidylethanolamine (PE) with oleic acid or with double-chain protonatable amphiphiles, and with pH-insensitive liposomes combining phosphatidylcholine (PC) and phosphatidylglycerol (PG). Fluorescence-microscopic observations indicate that double-chain protonatable amphiphiles remain tightly associated with pH-sensitive liposomes during incubations with CV-1 cell monolayers, and that cellular uptake of liposomes is strongly promoted by transferrin coupled to the liposome surface. Liposome-encapsulated araC showed much greater cytotoxicity toward CV-1 cells than did the free drug at equivalent concentrations under the same conditions. The cytotoxicity of encapsulated araC was strongly enhanced by liposome-conjugated transferrin and was maximal using pH-sensitive liposomes combining PE with the double-chain protonatable amphiphile N-(N'-oleoyl-2-aminopalmitoyl)serine. However, the drug was also markedly more cytotoxic when encapsulated in other types of transferrin-conjugated liposomes, including pH-insensitive PC/PG/cholesterol liposomes, than in the free form. The cytotoxicity of liposome-encapsulated araC is significantly attenuated by the nucleoside transport inhibitor nitrobenzothioinosine, and fluorescence microscopy using calcein-containing liposomes provides no evidence for efficient fusion between cellular membranes and any of the types of liposomes examined here. Based on these observations, we suggest that the major mechanism for cytoplasmic delivery of liposome-encapsulated araC is the carrier-mediated transport of drug that has been released from liposomes into the endosomal and/or the lysosomal compartments.

Stability and fusion of lipid vesicles containing headgroup-modified analogues of phosphatidylethanolamine.

We have used lipid mixing, contents mixing and contents-leakage assays to characterize the divalent cation-mediated interactions of vesicles composed of various headgroup-modified analogues of phosphatidylethanolamine, PE (N- and C-2-alkylated derivatives, and analogues with increased separations of the phosphoryl and amino groups) together with a low mole percentage of phosphatidylserine (PS). Vesicles containing different structural analogues of PE exhibit marked differences, both in the threshold divalent cation concentrations that are required to initiate vesicle-vesicle interactions and in the rates of contents mixing and leakage observed at suprathresholds divalent cation concentrations. The efficiencies of divalent cation-promoted contents leakage, and to a slightly lesser extent those of contents mixing, for PS/PE (analogue) vesicles show a marked inverse correlation with the lamellar-to-hexagonal II transition temperature (TH) of the PE (analogue) component. However, the destabilization kinetics for such vesicles show no abrupt changes over the temperature range around the equilibrium TH value measured for the vesicle lipids. Vesicles combining PS with different PE analogues exhibit divalent cation thresholds for aggregation that are not correlated with the TH values of the PE (analogue) components but appear instead to be correlated with the equilibrium interbilayer separations measured in multilamellar dispersions of these species. We have identified headgroup-modified analogues of PE that can be used to prepare vesicles that fuse more rapidly under a given set of conditions, or that show a bette ratio of fusion-to-contents-leakage rates, than do PE-containing vesicles. These results may be useful both for understanding better the bases for the high fusion-supporting ability of PE and for the preparation of lipid vesicles 'tailored' for particular practical applications.

Minor groove binding ligands alter the rotational positioning of DNA fragments on nucleosome core particles.

We have used hydroxyl radical and DNase I footprinting to examine the interaction of four AT-selective minor groove binding ligands (Hoechst 33258, distamycin, netropsin and berenil) with DNA fragments which have been reconstituted with nucleosome core particles. Hydroxyl radical footprints of reconstituted tyrT DNA show that all four ligands induce changes in the phased cleavage pattern, consistent with the suggestion that they cause the DNA to rotate by 180 degrees on the nucleosome surface. This observation was confirmed by a series of hydroxyl radical and DNase I footprinting experiments on a synthetic DNA fragment containing five different (A/T)4 sites spaced ten bases apart, in phase with the nucleosomal repeat. This fragment produces a phased cleavage pattern when bound to the nucleosome cores, with minima in the AT regions, suggesting that these regions are positioned with their narrow minor grooves facing towards the protein surface. In the presence of the minor groove binding ligands the hydroxyl radical cleavage maxima are shifted by about five base-pairs. It appears that the ligands have caused the DNA to rotate by about 180 degrees on the protein surface; those DNA regions which were facing out are turned in and vice versa. Regions to which the ligands are bound are turned away from the protein surface, thereby minimising electrostatic repulsion between the cationic charges on the ligand and protein. The absence of any observable footprints in the AT-regions suggests that these changes are induced at low levels of occupancy.

Are adjuvant therapies for tonsillectomy evidence based?

Our aim was to ascertain the current practice of adjuvant therapy for tonsillectomy and to determine whether it is evidence based. Anonymized postal questionnaires were sent to all UK otolaryngology consultants registered with the specialty association, and a literature search was performed using relevant search terms in all possible combinations. Among the responders there was little enthusiasm for routine intra-operative local anaesthesia, post-operative topical benzydamine hydrochloride (Difflam) spray or post-operative antibiotics. This is consistent with the lack of robust evidence to support any of these practices. Paracetamol (acetaminophen) is prescribed by almost 90 per cent for post-operative analgesia, and the current literature supports its efficacy and safety. Further, most practitioners combine paracetamol with opioids and/or non-steroidal anti-inflammatory drugs (NSAIDs). Evidence to support the additional use of these agents is, however, non-existent or limited. Some aspects of tonsillectomy care are uniform and evidence based. Others are heterogeneous and suffer from lack of adequate data in the literature.

Glucose turnover in type I diabetic subjects during exercise. Effect of selective and nonselective beta-blockade and insulin withdrawal.

OBJECTIVE: To assess the effect of selective beta 1-blockade (atenolol and betaxolol) and nonselective beta-blockade (propranolol) on glucose turnover in subjects with insulin-dependent (type I) diabetes mellitus during moderate exercise. RESEARCH DESIGN AND METHODS: Five subjects with type I diabetes were infused with insulin and then exercised for 1 h, after pretreatment with each of the three drugs or saline and, on a separate day, after withdrawal of insulin. Glucose turnover was measured using tritiated glucose. RESULTS: Plasma glucose, initially 9.2 +/- 0.5 mmol/L (mean +/- SE) when insulin infused and 14.0 +/- 0.8 when insulin was withdrawn, fell on exercise by 3.4 +/- 1.1 mmol/L (P < 0.05) saline, 4.0 +/- 0.8 mmol/L (P < 0.01) with betaxolol, 3.8 +/- 0.7 mmol/L (P < 0.01) with atenolol, 5.0 +/- 0.6 mmol/L (P < 0.005) with propranolol, and 1.7 +/- 1.0 mmol/L (NS) when insulin was withdrawn. Propranolol, but not the other beta-blockers, caused a significantly greater fall in glucose on exercise than during the control study. Glucose appearance rate (Ra) was similar basally and rose to an almost identical level in all five groups during exercise. Glucose disappearance rate (Rd) rose similarly during exercise, except after propranolol when the rise was significantly greater than with saline (P < 0.01). Failure of glucose to change significantly during exercise when insulin had been withdrawn was associated with the smallest rise in Rd and the highest nonesterified fatty acid concentrations. Propranolol and betaxolol, but not atenolol, reduced nonesterified fatty acids. CONCLUSIONS: We conclude that the greater fall in glucose on exercise after beta-blocking drugs is probably largely a direct effect of beta 2-blockade on muscle, increasing the exercise-induced rise in Rd glucose. This offers support to the use of beta 1-specific drugs, where beta-blockade is necessary in type I diabetes.

Extension of the therapeutic window for recombinant tissue plasminogen activator with argatroban in a rat model of embolic stroke.

BACKGROUND AND PURPOSE: Argatroban, a specific thrombin inhibitor, has been shown to reduce ischemic lesion size after focal cerebral ischemia in rats. In addition, recombinant tissue plasminogen activator (rtPA) has been shown to reduce ischemic lesion size in both rats and humans if given within 3 hours of symptom onset. We tested the hypothesis that the administration of argatroban with rtPA could extend the treatment window of stroke to 4 hours without increasing gross cerebral hemorrhage rates or reducing efficacy. METHODS: Male Wistar rats were subjected to middle cerebral artery (MCA) occlusion by a single fibrin-rich clot. After embolization, rats were administered argatroban at the following dose levels: 2.08, 6.25, and 18.75 microgram . kg(-1). min(-1). In a second experiment, rats received argatroban (6.25 microgram . kg(-1). min(-1)) or argatroban in combination with rtPA 4 hours after MCA occlusion. Tissue sections were then analyzed for lesion volume, gross hemorrhage and fibrin deposition. RESULTS: The 6.25 microgram. kg(-1). min(-1) dose demonstrated a significant reduction (P<0.05) in lesion volume after 48 hours (27.2+/-6.3%) compared with controls (35.3+/-3.7%). A significant reduction (P<0.05) in lesion volume was observed in the argatroban-plus-rtPA group (17.1+/-10.4%) compared with controls (35.3+/-3.7%). No increase in hemorrhagic transformation was observed. Fibrin deposition in the ipsilateral cortical microvasculature was significantly decreased in the 4-hour combination argatroban-plus-rtPA group compared with the controls (P<0.05). CONCLUSIONS: This study demonstrates that the combination of argatroban and rtPA extends the window of opportunity for treatment of stroke to 4 hours without increasing hemorrhagic transformation.

Gastroepiploic-coronary anastomosis. A viable alternative bypass graft.

Although increasing use is being made of arterial grafts (the internal mammary arteries) for direct myocardial revascularization, it is frequently not possible to reach the posterior surface of the heart with the internal mammary as either a pedicle or a free graft. Since June 1984 we have used the right gastroepiploic artery in nine patients as a pedicle graft to the distal right coronary artery (four patients), the posterior descending artery (three patients), and the distal circumflex branches (two patients). Eight patients survived the operation. Celiac axis opacification confirmed patency in six and coronary angiography strongly suggested patency in the remaining two. All survivors are functionally in New York Heart Association Class I or II. The early angiographic and clinical results demonstrate the feasibility of using the right gastroepiploic artery as a bypass graft to coronary vessels on the posterior surface of the heart when traditional conduits are unsuitable. If its long-term patency as a living arterial graft is similar to that of the internal mammary arteries, the gastroepiploic artery may become the coronary bypass graft of choice for the distal right coronary and circumflex systems.

The difficulty of quantifying the severity of carotid stenosis.

The problems of quantifying internal carotid stenoses were studied by analyzing 119 arteriograms. The normal carotid artery diameters, corrected for arteriographic magnification, are reported. Using these measurements, a theoretical comparison is made between the different methods that have been used for defining the severity of a carotid stenosis. Also, in the 119 arteriograms, the minimum residual lumen diameter of the stenosis was compared with the calculated percentage area of stenosis, the percentage diameter of stenosis, and the qualitative estimates of stenosis made by radiologists. Based on these data and other theories, it is concluded that the measurement of the minimum residual lumen diameter is the preferred method for quantifying the severity of carotid stenoses and that its use will avoid some of the current confusion in interpreting the results of noninvasive and clinical studies.

Intraoperative MIDCABG arteriography via the left radial artery: a comparison with Doppler ultrasound for assessment of graft patency.

BACKGROUND: Minimally invasive direct coronary artery bypass grafting involving beating heart left internal mammary artery to left anterior descending coronary artery anastomoses are performed with increasing frequency. Controversy exists regarding the need for intraoperative assessment of graft patency. METHODS: We designed a technique to perform arteriography of the left internal mammary artery by using left radial artery access and standard fluoroscopy to evaluate patency in the operating room. The last 50 of 87 minimally invasive direct coronary artery bypass grafting operations were evaluated by intraoperative arteriography and Doppler ultrasound. Angiograms were performed by the surgeon and involved cannulation and direct injection of contrast medium into the origin of the left internal mammary artery via the left radial artery. RESULTS: Total procedure time was less than 15 minutes. No injuries to the left internal mammary artery were identified. Anastomotic occlusions were identified in 4 cases (8%), 2 of which involved sequential diagonal and left anterior descending anastomoses. These were corrected at the time of surgery with 2 cases requiring conversion to standard coronary artery bypass grafting. Qualitative assessment of grafts with Doppler ultrasound failed to definitively identify these occlusions. There were no deaths and no perioperative infarctions. CONCLUSION: Intraoperative arteriography of the left internal mammary artery can be performed by the surgeon, and a significant number of anastomotic problems may be identified and corrected by using this technique. Therefore, a 100% early graft patency rate may be attainable.

Immunopathogenesis of hepatitis C viral infection: Th1/Th2 responses and the role of cytokines.

Hepatitis C virus is a common cause of hepatocellular injury that is associated with complex and vigorous immunologic mechanisms. Both humoral and cell-mediated immune responses participate in the host defense against hepatitis C viral infection, but there is increasing recognition of the roles played by the cell-mediated response, and in particular the cytokine system, in the immunopathogenesis of chronic hepatitis C. The cell-mediated response depends on cytotoxic and helper T-cell activity, and functions through the actions of cytokines to regulate macrophages, natural killer cells, and antiviral cellular proteins. Cytokines produced in the liver are essential in defending the host against hepatitis C invasion, but they have also been implicated in the hepatocellular injury seen in the majority of chronically infected patients. Cytokines are thought to be involved in the pathogenesis of hepatitis C under conditions where the virus can mutate effectively and evade T-cell immune defense mechanisms. Persistent infection upsets the balance between immunostimulatory and inhibitory cytokines which can prolong inflammation and lead to necrosis, fibrosis, and chronic liver disease.

CYP2E1-mediated modulation of valproic acid-induced hepatocytotoxicity.

OBJECTIVES: To determine the cytotoxicity of valproic acid (VPA) and its metabolite, 4-ene-valproic acid (4-ene-VPA) in human hepatoblastoma cells (Hep G2), and to study the modulatory effect of cytochrome P450 2E1 induction in this model. METHODS: Cells were exposed to VPA or 4-ene-VPA in the presence of either ethanol (EtOH), or EtOH combined with disulphiram (DS). Some cells were exposed to alpha-fluoro-VPA or to alpha-fluoro-4-ene-VPA in the absence of CYP2E1 inducers. Apoptosis and necrosis were measured by analyzing 6000 cells per sample using transmission electron microscopy, while cytokine release and apoptosis were quantitated by ELISA. RESULTS: VPA + EtOH increased VPA cytotoxicity. 4-ene-VPA + EtOH significantly increased toxicity, while DS + EtOH significantly reduced this toxicity. Alpha-fluorinated analogues reduced cytotoxicity compared to the corresponding VPA compounds. Neither VPA nor alpha-fluorinated VPA increased the release of IL-6 or TNF-alpha in media. A significant increase in the release of TNF-alpha was observed in cells exposed to 4-ene-VPA that further increased with EtOH exposure. CONCLUSIONS: Cells exposed to 4-ene-VPA experience greater cytotoxicity than those treated with VPA. Cytochrome P450 2E1 inducers enhance toxicity in VPA-exposed cells, while alpha-fluorination of VPA diminishes cytotoxicity by directly interfering with the beta-oxidation of the 4-ene-VPA metabolite.

Occult fever in surgical intensive care unit patients is seldom caused by sinusitis.

Febrile intensive care unit (ICU) patients were evaluated prospectively for sinusitis. Of 598 admissions, 26 patients with transnasal cannulas, ICU stays over 48 hours, and occult fevers were identified. These 26 underwent physical examinations and sinus computed tomographic (CT) scans. Maxillary centeses and cultures were done in patients with CT abnormalities. Patients with positive scans had nasal tubes removed and received decongestants. Scans were abnormal in 19 (73%). All patients with major CT changes had positive maxillary taps. Most infections were polymicrobial; enteric bacilli were common. Fever resolved with nonoperative care in 18 (95%) patients; in only 1 patient was fever primarily from sinusitis. Sinus CT scans are often abnormal in ICU patients with occult fevers and transnasal cannulas. Pneumatic otoscopy can serve as a screening tool. Most patients respond to nonoperative management. Remote infections are often present. Although radiographic nosocomial ICU sinusitis is common, it is seldom the sole source of fever or the proximate cause of significant morbidity.

A study of the fate of gum karaya in the rat.

Rats were fed a diet containing 5% gum karaya for 24 h and faeces and urine were collected over 72 h. Faeces were examined, after methanolysis, by gas chromatography--mass spectometry and the quantity and monosaccharide composition of the faecal polysaccharide were compared with the dose and original composition of the gum polysaccharide. Gum-derived rhamnose was not found in the urine. Indications of minor quantitative changes in composition but no evidence of extensive degradation or absorption of gum polysaccharide, were found.