The Salutary Effects of Diminazene, Lisinopril or Valsartan on Cisplatin - Induced Acute Kidney Injury in Rats: A Comparative Study

Nephrotoxicity as a cause of acute kidney injury (AKI) induced by cisplatin (CP), limits its usefulness as an anticancer agent. Diminazene, an angiotensin converting enzyme 2 activator, exhibited renoprotective properties on rat models of kidney diseases. This research aims to investigate the salutary effect of diminazene in comparison with lisinopril or valsartan in CP-induced AKI. The first and second groups of rats received oral vehicle (distilled water) for 9 days, and saline injection or intraperitoneal CP (6 mg/kg) on day 6, respectively. Third, fourth, and fifth groups received intraperitoneal injections of CP on day 6 and diminazene (15 mg/kg/day, orally), lisinopril (10 mg/kg/day, orally), or valsartan (30 mg/kg/day, orally), for 9 days, respectively. 24h after the last day of treatment, blood and kidneys were removed under anesthesia for biochemical and histopathological examination. Urine during the last 24 h before sacrificing the rats was also collected. CP significantly increased plasma urea, creatinine, neutrophil gelatinase-associated lipocalin, calcium, phosphorus, and uric acid. It also increased urinary albumin/creatinine ratio, N-Acetyl-beta-D-Glucosaminidase/creatinine ratio, and reduced creatinine clearance, as well the plasma concentrations of inflammatory cytokines [plasma tumor necrosis factor-alpha, and interleukin-1beta], and significantly reduced antioxidant indices [catalase, glutathione reductase , and superoxide dismutase]. Histopathologically, CP treatment caused necrosis of renal tubules, tubular casts, shrunken glomeruli, and increased renal fibrosis. Diminazine, lisinopril, and valsartan ameliorated CP-induced biochemical and histopathological changes to a similar extent. The salutary effect of the three drugs used is, at least partially, due to their anti-inflammatory and antioxidant effects. Keywords: Cisplatin, Diminazene, ACE2 activator, Lisinopril, Valsartan, Acute kidney injury.

Post-operative complications rates in patients undergoing emergency laparotomy in tertiary care hospital

Background: Post-operative complication may occur after explorative laparotomy whether elective or emergency. This study was aimed to evaluate the cause in which emergency laparotomy has been done, the frequency of different types of surgical complications after laparotomy in KR hospital, Mysore Medical college and Research Institute, Mysore, Karnataka. Aims and Objective: This study aims to evaluate the post-operative complications in patients undergoing emergency laparotomies at K R Hospital, Mysore Medical College and Research Institute, Mysore. Materials and Methods: This prospective observational study was carried out at the Department of General Surgery in Mysore Medical College, Mysore, Karnataka, during the period of October 2020–June 2021. All the patients who underwent emergency laparotomy were included in the study. They were followed up in the post-operative period and all the complications/sequelae developed were recorded. Results: The primary indications for an exploratory laparotomy are perforation peritonitis constituted (58.8%) cases followed by intestinal obstruction (13%), gallbladder perforation (10%), blunt and penetrating trauma abdomen (9.2%), and appendicular abscess/perforation (4.8%). In this study, most of the patients (77.2%) were between 21 and 50 years of age. Out of these, maximum cases (age) were found in the 4th decade, that is, 107 cases (42.8%). In this study local complication, surgical site infection (47.2%) was the most common complication followed by respiratory infection (30%), fever (38%), nausea and vomiting (14%), paralytic ileus (12.8%), UTI (10%), and thrombophlebitis (10.8%). Mortality was 6%. Conclusion: Post-operative complications are more common after emergency laparotomy as compared to elective laparotomies. Post-operative surgical site infection, nausea and vomiting, and fever are the most common complications which need adequate management and post-operative care.

Ameliorative effect of sesamin in cisplatin-induced nephrotoxicity in rats by suppressing inflammation, oxidative/nitrosative stress, and cellular damage

Nephrotoxicity of cisplatin (CP) involves renal oxidative stress and inflammation, and sesamin (a major liganin in many plants) has strong antioxidant and antiinflammatory actions. Therefore, we investigated here the possible mitigative action of sesamin on CP nephrotoxicity in rats. Sesamin was given orally (5 mg/kg/day, 10 days), and on the 7th day, some of the treated rats were injected intraperitoneally with either saline or CP (5 mg/kg). On the 11th day, rats were sacrificed, and blood and urine samples and kidneys were collected for biochemical estimation of several traditional and novel indices of renal damage in plasma and urine, several oxidative and nitrosative indices in kidneys, and assessment of histopathological renal damage. CP significantly and adversely altered all the physiological, biochemical and histopathological indices of renal function measured. Kidneys of CP-treated rats had a moderate degree of necrosis. This was markedly lessened when CP was given simultaneously with sesamin. Sesamin treatment did not significantly alter the renal CP concentration. The results suggested that sesamin had ameliorated CP nephrotoxicity in rats by reversing the CP-induced oxidative stress and inflammation. Pending further pharmacological and toxicological studies sesamin may be considered a potentially useful nephroprotective agent.

Ischemic monomelic neuropathy

Ischemic monomelic neuropathy is an uncommon complication associated with the creation of arteriovenous (AV) fistula for hemodialysis. After placement of an arteriovenous fistula, there can be shunting of arterial blood away from the distal extremity resulting in damage to distal nerve fibers with acute neurologic symptoms. It can present with global muscle pain, weakness, and a warm hand with palpable pulses starting within the 1 st h after the creation of the AV fistula. It is a devastating complication and can result in permanent disability. We hereby report two cases of ischemic monomelic neuropathy associated with the creation of a brachiocephalic AV fistula for hemodialysis access.

Fourier transform infrared spectroscopy (FTIR) analysis, chlorophyll content and antioxidant properties of native and defatted foliage of green leafy vegetables

FTIR analysis for five selected green leafy vegetables (GLVs) viz., Hibiscus cannabinus L., (kenaf), H. sabdariffa L., (roselle), Basella alba L., (vine spinach), B. rubra L. (malabar spinach) and Rumex vesicarius L., (sorrel) confirmed the presence of free alcohol, intermolecular bonded alcohol, intramolecular bonded alcohol, alkane, aromatic compounds, imine or oxime or ketone or alkene, phenol and amine stretching. The chlorophyll content was higher in native leaves of B. alba (2.96 g/kg) than defatted samples (1.11 g/kg). Total phenolic content (TPC) in H. sabdariffa native methanol extractives is more (17.6 g/kg) than defatted leaves (9.67 g/kg). Native B. rubra methanol extractives exhibited highest total flavonoid content (TFC) (21.59 g/kg), while that of R. vesicarius was lowest (3.21 g/kg). In general, antioxidant activities showed a significant reduction in retention of antioxidants in both native and defatted GLVs samples of ethanol and methanol extractives. Methanol extractives showed significantly stronger antioxidant activity probably due to greater solubility of phenolics and destruction of cellular components.

Characterization of major betalain pigments -gomphrenin, betanin and isobetanin from Basella rubra L. fruit and evaluation of efficacy as a natural colourant in product (ice cream) development

Basella rubra L. (Basellaceae) commonly known as Malabar spinach is a leafy vegetable which accumulates pigments in its fruits. To find out the feasibility of utilizing pigment rich extracts of its fruit as natural food colourant, fruits at different stages were analysed for pigment profiling, carbohydrate content, physical dimensions and weight. Total betalains content increased rapidly from early (green) through intermediate (half-done red-violet) to matured stage (red-violet). Maximum pigment content was observed in ripened fruits (143.76 mg/100 g fresh weight). The major betalain pigment characterized was gomphrenin I in ripened fruits (26.06 mg), followed by intermediate fruits (2.15 mg) and least in early fruits (0.23 mg) in 100 g of fresh deseeded fruits. Total carbohydrates content and the chroma values (redness) were also increased during ontogeny of B. rubra fruits. The textural characters of developing fruits showed the smoothness of green fruits with lower rupture force (0.16 N/s) than ripe ones (0.38 N/s). The pigment-rich fruit extract was used as natural colourant in ice-cream, to evaluate its effect on physicochemical properties and acceptability of the product. After six months of storage at -20 °C, 86.63 % colour was retained in ice-cream. The ice-cream had good overall sensorial quality and was liked by consumers indicating that addition of B. rubra fruit extract did not alter the sensory quality of the product. The colour values also indicate that there was no significant decrease of this pigment-rich extracts of fruits for its incorporation in food products.

A Tale of Deviation

Unilateral isolated Hypoglossal nerve palsy may result due to neoplasia, trauma, infections, autoimmune or vascular causes. We report a 52 year old male who presented with right hypoglossal nerve palsy and on evaluation was diagnosed to have prostatic malignancy with metastasis to the base of skull. Unilateral hypoglossal nerve palsy as the presenting feature of carcinoma prostate is rarely described.To the best of our knowledge, this is the third case report of unilateral hypoglossal palsy as a manifestation of prostatic carcinoma.

Inflammatory myofibroblastic tumor of the lung: unusual imaging findings

Inflammatory myofibroblastic tumor (IMT) is a rare neoplasm, most commonly seen in children and adolescents. It can occur in nearly every part of the body. Imaging properties and the clinical presentation of IMT can mimic malignant process. A 41-year-old female presented with cough of 3 months duration. Chest X-ray showed a coin shadow in the right upper lobe. Positron emission tomography/computed tomography scan showed a 3.2 × 2.4 cm lesion with homogeneous appearance with a very high fluorodeoxyglucose uptake value, suggesting a neoplastic process. She underwent lobectomy and the final diagnosis was IMT.

Dietary iron supplements and Moringa oleifera leaves influence the liver hepcidin messenger RNA expression and biochemical indices of iron status in rats

In this study, the effects of iron depletion and repletion on biochemical and molecular indices of iron status were investigated in growing male Wistar rats. We hypothesized that iron from Moringa leaves could overcome the effects of iron deficiency and modulate the expression of iron-responsive genes better than conventional iron supplements. Iron deficiency was induced by feeding rats an iron-deficient diet for 10 weeks, whereas control rats were maintained on an iron-sufficient diet (35.0-mg Fe/kg diet). After the depletion period, animals were repleted with different source of iron, in combination with ascorbic acid. Iron deficiency caused a significant (P < .05) decrease in serum iron and ferritin levels by 57% and 40%, respectively, as compared with nondepleted control animals. Significant changes in the expression (0.5- to100-fold) of liver hepcidin (HAMP), transferrin, transferrin receptor-2, hemochromatosis type 2, ferroportin 1, ceruloplasmin, and ferritin-H were recorded in iron-depleted and iron-repleted rats, as compared with nondepleted rats (P < .05). Dietary iron from Moringa leaf was found to be superior compared with ferric citrate in overcoming the effects of iron deficiency in rats. These results suggest that changes in the relative expression of liver hepcidin messenger RNA can be used as a sensitive molecular marker for iron deficiency.

Droplet digital PCR technology promises new applications and research areas

Digital Polymerase Chain Reaction (dPCR) is used to quantify nucleic acids and its applications are in the detection and precise quantification of low-level pathogens, rare genetic sequences, quantification of copy number variants, rare mutations and in relative gene expressions. Here the PCR is performed in large number of reaction chambers or partitions and the reaction is carried out in each partition individually. This separation allows a more reliable collection and sensitive measurement of nucleic acid. Results are calculated by counting amplified target sequence (positive droplets) and the number of partitions in which there is no amplification (negative droplets). The mean number of target sequences was calculated by Poisson Algorithm. Poisson correction compensates the presence of more than one copy of target gene in any droplets. The method provides information with accuracy and precision which is highly reproducible and less susceptible to inhibitors than qPCR. It has been demonstrated in studying variations in gene sequences, such as copy number variants and point mutations, distinguishing differences between expression of nearly identical alleles, assessment of clinically relevant genetic variations and it is routinely used for clonal amplification of samples for NGS methods. dPCR enables more reliable predictors of tumor status and patient prognosis by absolute quantitation using reference normalizations. Rare mitochondrial DNA deletions associated with a range of diseases and disorders as well as aging can be accurately detected with droplet digital PCR.

A method for red-violet pigments extraction from fruits of Malabar spinach (Basella rubra) with enhanced antioxidant potential under fermentation

Basella rubra fruit juice with a total soluble solids content of 5 to 9 (0)Brix was fermented using the wine yeast Saccharomyces cerevisiae. An 87.5 % of conversion of fermentable sugar was achieved. The TSS ((0)Brix) reduced from 0.60 (0)Brix to 0.17 (0)Brix (71.67 % decrease in TSS) upon performing fermentation of fruit juice water extract with Saccharomyces cerevisiae strain 2. There was 8 folds reduction in pigment quality as evidenced from fermentation. Besides, the potential increase of phenolics, thanks to a higher content of total betalains in general and betacyanins in particular when fermentation was carried out with S. cerevisiae strain 3. The DPPH (2, 2 -diphenyl-1-picrylhydrazyl hydrate) free radical scavenging potential (IC50) of fermented juice (1.9 mg.ml(-1)) was significant over control (2.4 mg.ml(-1)) extracts of B. rubra. The reducing power of fermented extracts was significantly high compared to control samples. The multiple antioxidant activity of fermented extract was also evident by significant reducing power assay when compared to its control samples.

Reactions of hydrated electrons with triazine derivatives in aqueous medium

A study is made of the kinetics and mechanism of the reaction of radiolytically produced hydrated electron (e-(aq)) with some triazine derivatives [1,3,5-triazine (T), 2,4,6-trimethoxy-1,3,5-triazine (TMT), 2,4-dioxohexahydro-1,3,5-triazine (DHT), 6-chloro N-ethyl N-(1-methylethyl)-1,3,5-triazine 2,4-diamine (atrazine, AT), and cyanuric acid (CA)] in aqueous medium using pulse and steady-state radiolysis techniques. The second-order rate constants were determined from the pseudo first-order decay of e(-)(aq) in the presence of triazines at 720 nm, and the values obtained with T, TMT, AT, and CA are in the order of 10(9) dm(3) mol(-1) s(-1) and that of DHT was 10(8) dm(3) mol(-1) s(-1) at pH 6. The transient absorption spectra from the reaction of e(-)(aq) with T and TMT are characterized by their lambda(max) at 310 nm, and those of DHT and CA are around 280 and 290 nm, respectively. However, a very weak and featureless absorption spectrum is obtained from AT. On the basis of the spectral evidence and on the quantitative electron transfer from the transient intermediates to the oxidant, methyl viologen (MV(2+)), the intermediate radicals are assigned to N-protonated electron adducts (with the unpaired spin density at carbon) of triazines. The degradation profiles, monitored as the disappearance of parent triazine concentrations as a function of dose, obtained with AT, TMT, CA, and DHT, highlight the potential use of e-(aq) in the degradation of triazines.

Reaction of Hydroxyl Radicals with Azacytosines: A Pulse Radiolysis and Theoretical Study

Pulse radiolysis and density functional theory (DFT) calculations at B3LYP/6-31+G(d,p) level have been carried out to probe the reaction of the water-derived hydroxyl radicals (*OH) with 5-azacytosine (5Ac) and 5-azacytidine (5Acyd) at near neutral and basic pH. A low percentage of nitrogen-centered oxidizing radicals, and a high percentage of non-oxidizing carbon-centered radicals were identified based on the reaction of transient intermediates with 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate), ABTS2-. Theoretical calculations suggests that the N3 atom in 5Ac is the most reactive center as it is the main contributor of HOMO, whereas C5 atom is the prime donor for the HOMO of cytosine (Cyt) where the major addition site is C5. The order of stability of the adduct species were found to be C6-OH_5Ac*>C4-OH_5Ac*>N3-OH_5Ac*>N5-OH_5Ac* both in the gaseous and solution phase (using the PCM model) respectively due to the additions of *OH at C6, C4, N3, and N5 atoms. These additions occur in direct manner, without the intervention of any precursor complex formation. The possibility of a 1,2-hydrogen shift from the C6 to N5 in the nitrogen-centered C6-OH_5Ac* radical is considered in order to account for the experimental observation of the high yield of non-oxidizing radicals, and found that such a conversion requires activation energy of about 32 kcal/mol, and hence this possibility is ruled out. The hydrogen abstraction reactions were assumed to occur from precursor complexes (hydrogen bonded complexes represented as S1, S2, S3, and S4) resulted from the electrostatic interactions of the lone pairs on the N3, N5, and O8 atoms with the incoming *OH radical. It was found that the conversion of these precursor complexes to their respective transition states has ample barrier heights, and it persists even when the effect of solvent is considered. It was also found that the formation of precursor complexes itself is highly endergonic in solution phase. Hence, the abstraction reactions will not occur in the present case. Finally, the time dependent density functional theory (TDDFT) calculations predicted an absorption maximum of 292 nm for the N3-OH_5Ac* adduct, which is close to the experimentally observed spectral maxima at 290 nm. Hence, it is assumed that the addition to the most reactive center N3, which results the N3-OH_5Ac* radical, occurs via a kinetically driven process.

Childhood acute disseminated encephalomyelitis presenting as Foix-Chavany-Marie syndrome

A 10-year-old boy presented with anarthria and bilateral central faciolinguovelopharyngeomasticatory paralysis with "automatic voluntary dissociation" suggestive of Foix-Chavany-Marie syndrome or anterior opercular syndrome following a nonspecific upper respiratory infection. Brain magnetic resonance imaging revealed bilateral subcortical perisylvian demyelination in addition to multiple subcortical white-matter demyelination. The clinicoradiologic picture suggested acute disseminated encephalomyelitis. The child recovered completely following intravenous methylprednisolone and intravenous immunoglobulin therapy. This is the first report of anterior opercular syndrome in childhood acute disseminated encephalomyelitis.

Fat emulsification measured using NMR transverse relaxation

This paper presents a novel method of measuring the droplet size in oil-in-water emulsions. It is based on changes in the NMR transverse relaxation rate due to the effect of microscopic magnetic susceptibility differences between fat droplets and the surrounding water. The longitudinal and transverse relaxation rates of a series of emulsions with constant oil volume fraction and five different mean droplet sizes, in the range 0.4-20.9 microm, were measured in vitro at 37 degrees C using EPI. While the longitudinal relaxation rate 1/T(1) did not change significantly, 1/T(2) was observed to increase with mean droplet size. The measured changes in 1/T(2) were found to be in good agreement with results predicted from proton random walk simulations, and were also consistent with analytical solutions based on an outer sphere relaxation model. Measurements of 1/T(2) on emulsions with a higher oil volume fraction, and on emulsions of a fixed size where the water phase was doped with gadolinium to modulate the susceptibility difference between the phases, also showed the predicted behavior. As part of this study the susceptibility difference between olive oil and water was measured to be 1.55 ppm.

Effect of meal viscosity and nutrients on satiety, intragastric dilution, and emptying assessed by MRI

The relationship between the intragastric distribution, dilution, and emptying of meals and satiety was studied using noninvasive magnetic resonance imaging techniques in 12 healthy subjects with four polysaccharide test meals of varying viscosity and nutrient content as follows: 1) low-viscosity nonnutrient, 2) low-viscosity nutrient, 3) high-viscosity nonnutrient, and 4) high-viscosity nutrient. Increasing the nutrient content of the high-viscosity meal delayed gastric emptying from 46 +/- 9 to 76 +/- 6 min (P < 0.004), whereas increasing viscosity had a smaller effect. The volume of secretions within the stomach 60 min after ingestion was higher for the high-viscosity nutrient meal (P < 0.04). A simple model to calculate the total volume of secretion added to the test meal is presented. Color-coded dilution map images showed the heterogeneous process of progressive gastric dilution of high-viscosity meals, whereas low-viscosity meals were uniformly diluted. Fullness was found to be linearly related to total gastric volumes for the nutrient meals (R(2) = 0.98) and logarithmically related for the nonnutrient meals (R(2) = 0.96). Fullness was higher for high- compared with low-viscosity meals (P < 0.02), and with the nutrient meals this was associated with greater antral volumes (P < 0.05).

Assessment of antral grinding of a model solid meal with echo-planar imaging

Mathematical modeling of how physical factors alter gastric emptying is limited by lack of precise measures of the forces exerted on gastric contents. We have produced agar gel beads (diameter 1.27 cm) with a range of fracture strengths (0.15-0.90 N) and assessed their breakdown by measuring their half-residence time (RT(1/2)) using magnetic resonance imaging. Beads were ingested either with a high (HV)- or low (LV)-viscosity liquid nutrient meal. With the LV meal, RT(1/2) was similar for bead strengths ranging from 0.15 to 0.65 N but increased from 22 +/- 2 min (bead strength <0.65 N) to 65 +/- 12 min for bead strengths >0.65 N. With the HV meal, emptying of the harder beads was accelerated. The sense of fullness after ingesting the LV meal correlated linearly (correlation coefficient = 0.99) with gastric volume and was independently increased by the harder beads, which were associated with an increased antral diameter. We conclude that the maximum force exerted by the gastric antrum is close to 0.65 N and that gastric sieving is impaired by HV meals.

NMR diffusometry of oil-in-water emulsions

The diffusion propagator of the continuous aqueous phase of concentrated oil-in-water emulsions is used to probe the relationship between emulsion microstructure and bulk rheological properties. This is done by expanding the stimulated echo amplitude, S(q,Delta), as a multiple exponential time series expansion in Delta, with wavevector dependent expansion coefficients. These coefficients are compared with predictions from several theoretical models for three types of stable emulsion, each differing in microstructure. Empiric relationships between the wavevector expansion coefficients and bulk rheology are established.

Characterization of a Polydisperse Depletion-Flocculated Emulsion

The addition of nonadsorbing polymer to an alkane-in-water emulsion causes the droplets to flocculate into a space-spanning, stress-bearing network. We report rheological measurements of an emulsion of 1-bromohexadecane-in-water flocculated by hydroxy-ethylcellulose. Small-deformation oscillatory measurements allowed characterization of the structure during formation and an indication of the strength of the resulting network. Emulsions without polymer, and polymer solutions alone, showed essentially viscous behavior, with dominant viscous modulus over the whole frequency range (0.01-10 Hz). However, the emulsion containing polymer demonstrated a significant elastic modulus, dependent on the oil and polymer concentrations, attributable to interdroplet depletion interactions. Power-law relationships were observed between the elastic modulus, elastic strain limit, and oil volume fraction, but the indices were lower than those predicted by fractal models, giving unrealistic fractal dimensionalities. The modulus increased exponentially with polymer concentration, but the elastic strain limit was independent of added polymer. The rate of formation of the network was not consistent with diffusion-controlled aggregation. Copyright 2000 Academic Press.

Comparison of heat and pressure treatments of skim milk, fortified with whey protein concentrate, for set yogurt preparation: effects on milk proteins and gel structure

Heat (85 degrees C for 20 min) and pressure (600 MPa for 15 min) treatments were applied to skim milk fortified by addition of whey protein concentrate. Both treatments caused > 90 % denaturation of beta-lactoglobulin. During heat treatment this denaturation took place in the presence of intact casein micelles; during pressure treatment it occurred while the micelles were in a highly dissociated state. As a result micelle structure and the distribution of beta-lactoglobulin were different in the two milks. Electron microscopy and immunolabelling techniques were used to examine the milks after processing and during their transition to yogurt gels. The disruption of micelles by high pressure caused a significant change in the appearance of the milk which was quantified by measurement of the colour values L*, a* and b*. Heat treatment also affected these characteristics. Casein micelles are dynamic structures, influenced by changes to their environment. This was clearly demonstrated by the transition from the clusters of small irregularly shaped micelle fragments present in cold pressure-treated milk to round, separate and compact micelles formed on warming the milk to 43 degrees C. The effect of this transition was observed as significant changes in the colour indicators. During yogurt gel formation, further changes in micelle structure, occurring in both pressure and heat-treated samples, resulted in a convergence of colour values. However, the microstructure of the gels and their rheological properties were very different. Pressure-treated milk yogurt had a much higher storage modulus but yielded more readily to large deformation than the heated milk yogurt. These changes in micelle structure during processing and yogurt preparation are discussed in terms of a recently published micelle model.

NMR Q-space microscopy of concentrated oil-in-water emulsions

The pulsed field gradient stimulated echo technique with selective excitation is used to probe the diffusion of water in the continuous phase of concentrated oil-in-water emulsions. The dependence of the echo amplitude, S(q,Delta), on wavevector, q, and diffusion time, Delta, shows that the water diffusion propagator is sensitive to emulsion microstructure. This is analyzed using a multiple exponential time series expansion of S(q,Delta) in Delta, with wavevector dependent expansion coefficients. These coefficients are compared with predictions from several theoretical models for three types of stable emulsion, each differing in microstructure. The relationship between the nuclear magnetic resonance q-space measurements and bulk rheology for all three types of emulsion is also explored.

Gastric response to increased meal viscosity assessed by echo-planar magnetic resonance imaging in humans

Normal meals are highly viscous, and viscosity is a key factor in influencing gastric emptying of food. However, the process of meal dilution and mixing is difficult to assess with the use of conventional methods. The aim of this study was to validate an in vivo, novel, noninvasive, echo-planar magnetic resonance imaging (EPI) technique, capable of monitoring the viscosity of a model meal, and to use this to investigate the effects of viscosity on gastric emptying, meal dilution and satiety. Healthy volunteers (n = 8) ingested 500 mL of locust bean gum (0.25, 0.5, 1.0 or 1.5 g/100 g), nonnutrient, liquid meals of varying viscosities, and labeled with a nonabsorbable marker, phenol red. Meal viscosity was calibrated against the water proton transverse relaxation rate (T(2)(-1)) in vitro before ingestion, thus viscosity was measured in vivo via EPI measurements of T(2)(-1). Viscosity and dilution were also measured directly using nasogastric aspirates. Gastric volumes as measured by EPI, fullness, appetite and hunger were also assessed serially. Before ingestion, the log of initial meal viscosity was linearly related to T(2)(-1) (n = 8, r(2) = 0.95). Similarly, T(2)(-1) measured in vivo was also linearly related to the viscosity of the aspirates (r(2) = 0.88). All meals underwent rapid dilution, leading to a reduction in viscosity, which was greatest for the most viscous meal (P < 0.01). Surprisingly, despite the fact that the initial meal viscosity varied 1000-fold, there was only a small delay in gastric emptying (P for trend < 0.05). The area under the curve for satiety increased with initial meal viscosity, whereas that for hunger decreased (P < 0.05). In conclusion, the viscosity of a meal in vivo can be measured noninvasively using EPI. The stomach responds to meal ingestion by rapid intragastric dilution, causing a reduction of meal viscosity, and gastric emptying is minimally delayed. However, increased viscosity is associated with more prolonged satiety.

II. Steady-State Rheological Investigations

Depletion flocculation of an alkane-in-water emulsion has previously been found to induce phase separation and, above certain polymer and oil concentrations, a delay period prior to the onset of creaming. In this paper the steady-state viscometry of an emulsion of 1-bromohexadecane-in-water has been investigated in the presence of hydroxyethylcellulose as the depletion flocculant. We have sought to characterize the flow behavior of this emulsion system and determine the characteristic rheology during the delay period. The use of this near-density-matched system eliminates the effect of creaming, and we have, therefore, characterized the delay period by reference to the behavior of a related system, differing only in oil composition. At oil and polymer concentrations conducive to the presence of a delay period, the emulsions were found to be shear thinning, whereas the emulsion system in the absence of polymer and the isolated continuous phases were Newtonian. The structure formation influencing the rheology of the emulsions at high polymer concentrations was attributed entirely to interdroplet depletion interactions. The concept of dynamic yield stress for such a system is discussed and the consequences for the structure of a buoyancy-resisting space-spanning phase or "transient gel." Copyright 1998 Academic Press.

I. Creaming Behavior

We report an experimental investigation on the creaming behavior of flocculated, polydisperse, oil-in-water emulsions. Flocculation is by addition of a depletion flocculant, the polymer hydroxyethylcellulose (HEC), at a range of concentrations. The creaming behavior is dependent on the oil volume fraction and polymer concentration. At low concentrations of HEC, the droplets cream either individually or in two populations, a flocculated phase, and a coexistent phase of individual droplets. At higher HEC concentrations, the droplets appear to cream as a single entity, with a sharp lower boundary, separating the region with droplets from a clear serum at the base of the container. In these emulsions, and in some of the coexistent ones, there is a significant delay before creaming starts. Once started they cream at a constant rate. We have identified the continuous phase viscosity as a major factor. The aim of this work is to elucidate the mechanisms underlying the delay before creaming. We propose that as soon as they flocculate, the emulsions form space-filling structures, which slowly rearrange until channels are formed that allow the flow of bulk continuous phase to the base of the container. Scaling arguments are presented that suggest the delay could be related to the single-droplet diffusion rate. Copyright 1998 Academic Press.

Echo-planar imaging relaxometry to measure the viscosity of a model meal

A method for measuring noninvasively the viscosity of a polysaccharide model meal using the known relationship between relaxation times and polysaccharide concentration in solution in vitro is presented. The aim is to develop a method for monitoring digesta viscosity in vivo, using EPI to capture the motion of the gastrointestinal lumen. The transverse relaxation rate T-12 of locust bean gum solutions was calibrated against the zero-shear viscosity at 37 degreesC. Differences in viscosity were distinguished significantly using T-12 measurements. T-12 and viscosity were insensitive to exposure to gastric juice and changes in pH, and the model meal was well received by volunteers and provided good contrast in vivo in EPI images. Therefore it would be possible to use this method to monitor the changes in meal viscosity within the gastric lumen in vivo.