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PubMed1981

Analysis of moisture sorption hysteresis in hard gelatin capsules, maize starch, and maize starch: drug powder mixtures.

Moisture sorption and desorption isotherms at 25 degrees C for hard gelatin capsules, maize starch and 50:50 mixes of maize starch: barbitone and maize starch: sodium barbitone have been measured. The sorption hysteresis observed in all four systems studied has been analysed according to the hypothesis of Young & Nelson (1967a) which distinguishes three locations for moisture--monolayer adsorbed moisture, normally condensed moisture and absorbed moisture. Hysteresis is explained by a separation of absorption and desorption isotherms for absorbed moisture and different patterns of moisture distribution are demonstrated in the four systems examined.

Adsorption↗

PubMed2000

Introduction of raw starch-binding domains into Bacillus subtilis alpha-amylase by fusion with the starch-binding domain of Bacillus cyclomaltodextrin glucanotransferase.

We constructed two types of chimeric enzymes, Ch1 Amy and Ch2 Amy. Ch1 Amy consisted of a catalytic domain of Bacillus subtilis X-23 alpha-amylase (Ba-S) and the raw starch-binding domain (domain E) of Bacillus A2-5a cyclomaltodextrin glucanotransferase (A2-5a CGT). Ch2 Amy consisted of Ba-S and D (function unknown) plus E domains of A2-5a CGT. Ch1 Amy acquired raw starch-binding and -digesting abilities which were not present in the catalytic part (Ba-S). Furthermore, the specific activity of Ch1 Amy was almost identical when enzyme activity was evaluated on a molar basis. Although Ch2 Amy exhibited even higher raw starch-binding and -digesting abilities than Ch1 Amy, the specific activity was lower than that of Ba-S. We did not detect any differences in other enzymatic characteristics (amylolytic pattern, transglycosylation ability, effects of pH, and temperature on stability and activity) among Ba-S, Ch1 Amy, and Ch2 Amy.

Amino Acid Sequence↗

PubMed1983

A study of 'starch blockers' in man using 13C-enriched starch as a tracer.

It is claimed that commercial preparations of an alpha-amylase inhibitor, taken in tablet form 10 min before a meal, will inhibit the digestion of up to 100 g starch in the following meal. This was tested by giving five obese women three meals each containing cornflour enriched with 13C after a tablet of 'Starchex' or 'Calorex' or a placebo, in randomized sequence. The response to the meal in the rate of evolution of 13CO2, the increase in plasma insulin and the increase in blood sugar did not differ with the type of tablet which preceded the meal. We conclude that these starch-blocker tablets do not affect starch digestion or absorption in vivo.

Adult↗

PubMed1997

A new generation starch product as excipient in pharmaceutical tablets. III. Parameters affecting controlled drug release from tablets based on high surface area retrograded pregelatinized potato starch.

This paper describes the general applicability of a new pregelatinized starch product in directly compressible controlled-release matrix systems. It was prepared by enzymatic degradation of potato starch followed by precipitation (retrogradation), filtration and washing with ethanol. The advantages of the material include ease of tablet preparation, the potential of a constant release rate (zero-order) for an extended period of time and the possibility to incorporate high percentages of drugs with different physicochemical properties. Constant release profiles are the result of solvent penetration into the tablet. For theophylline as test drug, constant release profiles could be realized up to a drug content of 75%. This illustrates the possibility to control the release of highly dosed drugs. Release rates from retrograded pregelatinized starch tablets can be enhanced or decreased to the desired profile by different parameters, like geometries of the tablet, compaction force and the incorporation of additional excipients. For procaine HCl it is demonstrated that larger tablets show slower release rates. The incorporation of soluble excipients like lactose and mannitol results for paracetamol in enhanced release rates. The delivery of bases and their salts can be modified by the incorporation of organic acid or alkaline excipients, as is demonstrated for lidocaine and procaine HCl.

Journal Article↗

PubMed2004

The structure of starch can be manipulated by changing the expression levels of starch branching enzyme IIb in rice endosperm.

When the starch branching enzyme IIb (BEIIb) gene was introduced into a BEIIb-defective mutant, the resulting transgenic rice plants showed a wide range of BEIIb activity and the fine structure of their amylopectins showed considerable variation despite having the two other BE isoforms, BEI and BEIIa, in their endosperm at the same levels as in the wild-type. The properties of the starch granules, such as their gelatinization behaviour, morphology and X-ray diffraction pattern, also changed dramatically depending on the level of BEIIb activity, even when this was either slightly lower or higher than that of the wild-type. The over-expression of BEIIb resulted in the accumulation of excessive branched, water-soluble polysaccharides instead of amylopectin. These results imply that the manipulation of BEIIb activity is an effective strategy for the generation of novel starches for use in foodstuffs and industrial applications.

Journal Article↗

PubMedDate not supplied

Does hydroxyethyl starch cause lichen planus? Lichen planus in a long-time routine blood donor never exposed to hydroxyethyl starch.

A case of lichen planus attributed to exposure to hydroxyethyl starch has been reported previously. In this report, a case of lichen planus in a healthy blood donor never exposed to hydroxyethyl starch is presented, the statistical incidence of lichen planus in healthy leukapheresis donors is approximated, and a description of the Koebner phenomenon, which could falsely lead to incorrect conclusions regarding cause and effect in this disease, is discussed.

Adult↗

PubMed1979

In vitro comparison of the erythrocyte sedimenting properties of dextran, hydroxyethyl starch and a new low-molecular-weight hydroxyethyl starch.

A low-molecular-weight preparation of hydroxyethyl starch (LMW-HES) may serve as a desirable substitute for the erythrocyte sedimenting agents presently employed to improve neutrophil yields in centrifugation and gravity leukapheresis. The cell-separating and erythrocyte-sedimenting properties of LMW-HES, assessed in vitro by the recovery of various blood cells in plasma supernatant fluids, were similar to those of the higher-molecular-weight hydroxyethyl starch in current use and to dextran under a variety of conditions. These data predict success for LMW-HES as a sedimenting agent in leukapheresis and recommend that it be evaluated in clinical trials.

Blood Platelets↗

PubMed1975

Intragranular starch: comparison of starch USP and modified cornstarch.

Incorporation of starch USP or a modified cornstarch within the granules of several drug formulations was investigated. In general, the formulation containing the modified starch exhibited improved processing characteristics as well as improved tablet properties. A comparison of a granulated and a direct compression formulation of the same ingradients indicated that granulation of an active ingredient is not necessarily detrimental to its (pharmaceutical) availability.

Acetaminophen↗

PubMed1988

Starch-induced overeating and overweight in rats: influence of starch type and form.

In Experiment 1, adult female rats were fed, in addition to chow and water, a carbohydrate source that consisted of pure amylopectin corn starch or hydrolyzed corn starch (Polycose) in either a dry powder form or a hydrated gel form. Over the 30-day test periods, carbohydrate intake, total food intake, and body weight gain were greater with the Polycose than with the amylopectin, and greater with the gel form than with the powder form of the carbohydrates. The amylopectin gel produced overeating and overweight relative to a chow-fed control group, although the effects were less than that obtained with the Polycose gel. In a second experiment, test meals of the carbohydrate gels produced larger postmeal increases in plasma glucose than did the carbohydrate powders. There was no effect of carbohydrate type (amylopectin vs. Polycose) on the plasma glucose response. In Experiment 3, the addition of amylopectin to a Polycose gel reduced carbohydrate and total caloric intake. Both orosensory and postingestive factors may contribute to the differential food intake and body weight gains produced by the different types (Polycose vs. amylopectin) and forms (gel vs. powder) of carbohydrates.

Amylopectin↗

PubMed2000

[Comparison of hydroxyethyl starch solutions derived from potato and corn starch] .

OBJECTIVE: The study was designed to investigate the effects of hydroxyethyl starch (HES) solutions derived from potato (p) compared to HES derived from corn (c) starch on the colloidosmotic pressure, plasma viscosity, and to measure the plasma and urine concentration. METHODS: After approval by the Ethics Committee, and having obtained informed consent, we recruited 20 patients undergoing lumbar disc surgery who received either 1000 ml of p-HES or c-HES (MW 200,000 DS 0.5) in a randomized, single-blind way. Colloidosmotic pressure, plasma viscosity and the plasma concentration were measured before and 30, 90, 240 min and one day after the infusion. Statistical analysis was performed using chi-square and Mann-Whitney test. There were no differences between the two groups in regard to demographics and anesthesia. RESULTS: Plasma viscosity and colloidosmotic pressure did not change significantly during that time. There were no differences in plasma concentration and excretion of both solutions. The peak plasma concentration was reached after 30 min in both groups (8.57 +/- 3.92 g/l c-group and 7.67 +/- 4.68 g/l p-group) and declined thereafter. Within 6 h 38% (c-group 23.0 +/- 3.2 g HES) and 28% (p-group 16.8 +/- 1.6 g HES) of the infused HES were found in the urine. 12 h later about 50% was excreted. CONCLUSION: The present study demonstrated that there was no clinically apparent effect on hematorheology and pharmacokinetics between these two solutions.

Adult↗

PubMed2000

[Hydroxyethyl starch accumulation in the skin with special reference to hydroxyethyl starch-associated pruritus].

BACKGROUND AND OBJECTIVE: Hydroxyethyl starch (HES) is a colloidal infusion fluid that has for a long time been used in emergency situations and to improve impaired blood perfusion. In the last few years there have been numerous reports about treatment resistant pruritus, often persisting for months, after HES infusion. We investigated the intracellular uptake of HES in the skin, special attention being focused on associated pruritus. PATIENTS AND METHODS: Skin biopsies were obtained from 120 patients (120 men, 35 women) and examined immunohistochemically and for their ultrastructure. Three patients had received various HES preparations, while 22 had been given dextran. Five patients who had received no infusions served as controls. RESULTS: All patients given HES had lysosomal deposits in the histiocytes, some of them also in cutaneous epithelium and endothelium. The extent of lysosomal storage correlated with the amount of infused HES and the interval between biopsy and last HES infusion. Consecutive biopsies in some cases demonstrated a definite decrease over the years of HES deposits in the vacuoles. This suggests that HES is regularly metabolized in the skin. Pruritus after high cumulative doses of HES was closely correlated with HES deposition in cutaneous nerves. CONCLUSIONS: These results emphasize the need for starch derivatives that can be better metabolized and for better adapted infusion schedules to reduce the high incidence of pruritus.

Adolescent↗

PubMed1998

Compromised blood coagulation: an in vitro comparison of hydroxyethyl starch 130/0.4 and hydroxyethyl starch 200/0.5 using thrombelastography.

UNLABELLED: We compared the effects of progressive in vitro hemodilution (30% and 60%) on blood coagulation in 80 patients receiving one of two different 6% hydroxyethyl starch (HES) solutions using thrombelastography (TEG). The newly developed solution has a mean molecular weight of 130 kD and a degree of substitution, defined as the average number of hydroxyethyl groups per glucose moiety, of 0.4 (HES 130/0.4); the conventional solution has a mean molecular weight of 200 kD and a degree of substitution of 0.5 (HES 200/0.5). Both HES solutions significantly compromised blood coagulation, as seen by an increase in reaction time and coagulation time and a decrease in angle alpha, maximal amplitude, and coagulation index (all P < 0.05). There was no difference between HES 130/0.4 and HES 200/0.5 diluted blood (P > 0.05 for all TEG variables). When analyzing the intrinsic HES effect by taking hemodilution with 0.9% saline into account, progressive hemodilution with both HES solutions resulted in an increasing clot lysis (P < 0.05 after 60 min). Again, there was no difference between HES 130/0.4 and HES 200/0.5 diluted blood. We conclude that HES 130/ 0.4 and HES 200/0.5 compromise blood coagulation to the same degree. IMPLICATIONS: Progressive in vitro hemodilution using hydroxyethyl starch (HES) compromises blood coagulation. We observed similar effects of a new HES solution with a mean molecular weight of 130 kD and a degree of substitution of 0.4 (HES 130/0.4), compared with the conventional HES 200/0.5.

Blood Coagulation↗

PubMed2006

Hydroxyethyl starch 130 kd/0.4 and albumin improve CVVH biocompatibility whereas gelatin and hydroxyethyl starch 200 kd/0.5 lead to adverse side effects of CVVH in anesthetized pigs.

UNLABELLED: Both fluid management and renal replacement therapies play a fundamental role in the treatment of critically ill patients. In a recent in vitro study, we have shown specific interactions of different colloids and the hemocompatibility of hemofilters. The present study was performed to compare the five most common fluids for volume resuscitation, i.e., normal saline (SAL), hydroxyethyl starch 130 kd/0.4 (HES130), hydroxyethyl starch 200 kd/0.5 (HES200), albumin (ALB), and gelatin (GEL) with respect to their interaction with continuous venovenous hemofiltration (CVVH) in anesthetized domestic pigs. METHODS: Animals (n = 63) were allocated randomly to the fluid type and the respective subgroups, which were divided into control and CVVH groups (n = 6 ndash; 7 per group). Bolus infusion of group specific fluid was followed by a bolus of heparin and the initiation of hemofiltration in CVVH groups. Thereafter, fluids were infused at constant rates, and heparin application was adjusted to keep the activated clotting time at 200 to 250 s. Hemodynamics, airway pressures, pulmonary gas exchange, diuresis, creatinine clearance, and blood cell counts were investigated during the entire procedure (10 ndash; 12 hours). RESULTS: Basics of in vivo effects of SAL, HES130, and ALB were not altered during CVVH. HES130 and ALB enabled stable hemocompatibility, diuresis, and hemodynamics in the respective groups. In contrast, organ functions were significantly different between control and CVVH groups when animals were treated with GEL or HES200. In particular, during CVVH, HES200 led to reduced platelet counts, deteriorated hemodynamics, and increasing airway pressures during CVVH. GEL led to increasing airway pressures, a decrease in pulmonary gas exchange, deteriorated hemodynamics, altered renal histomorphology, reduced platelet counts, and reduced hemoglobin. CONCLUSIONS: Direct in vivo effects of colloids in anaesthetized and ventilated pigs are not predictable for their effects during CVVH. Interaction between CVVH and every volume substitute occur in a highly specific manner. This observation could be helpful to explain contradictory study results and should be considered for future study designs.

Albumins↗

PubMed2000

Structural and immunochemical homologies between foxtail millet glutelin 60 kDa and starch granule-bound starch synthase proteins from rice, barley, corn and wheat grains.

Foxtail millet glutelin 60 kDa (MG60) was purified by preparative SDS-PAGE, and the N-terminal amino acid sequence was determined within 20 residues. The result demonstrated that the primary structure at N-terminal of MG60 was almost identical to those of the granule-bound starch synthase (GBSS) proteins from rice, barley, corn, wheat and potato. The existence of common epitopes among MG60 and GBSS proteins from these starch-storing cereals were corroborated by immunoblot analysis using antisera raised against MG60. These facts strongly suggest a close relationship between MG60-like glutelins and GBSS proteins.

Amino Acid Sequence↗

PubMed1991

Promotive and inhibitory effects of raw starch adsorbable fragments from pancreatic alpha-amylase on enzymatic digestions of raw starch.

The enzymatically inactive but raw-starch-adsorbable peptide fragments designated as Gp-pan P and Gp-pan I were obtained from a tryptic digest of heat-inactivated hog pancreatic alpha-amylase. These two glycopeptide fragments were purified with Sephadex G-75, DEAE-Sephadex A-50, and HPLC and were found to be homogeneous on disc gel electrophoresis. Gp-pan P and I had molecular weights of 20,000 and 30,000 with SDS-PAGE, carbohydrate contents of 10% and 7%, N-terminal amino acids Gly-Trp and Ala-Val, and C-terminal amino acids Gly-Arg and Ile-Lys. Gp-pan P had promotive but Gp-pan I inhibitory effects on raw starch digestion by Aspergillus awamori var. kawachi glucoamylase I and Bacillus subtilis 65 alpha-amylase.

Adsorption↗

PubMed1994

Bioavailability of starch in bread products. Postprandial glucose and insulin responses in healthy subjects and in vitro resistant starch content.

Attempts to reduce glycaemia to bread were evaluated in healthy subjects. The contents of in vitro resistant starch (RS) were also measured in the bread products. The potential of including intact barley kernels at different concentrations (80% and 40%) was tested in two products (SCB-80 and SCB-40). Three variants of barley bread made from wholemeal were also studied: ordinary (WMB), sourdough fermented (WMB-s) and one made from scalded flour (SWMB). A commercial pumpernickel bread (PB) based on sourdough fermented rye kernels was included for comparison and a white wheat bread (WWB) used as reference for calculation of glycaemic index. The glycaemic and insulinaemic indices for SCB-80 were 33 and 39, and for PB 69 and 61, respectively. The glycaemic index was lowered also in case of SCB-40 (66). No differences in indices were found between the WMB products or versus WWB. A high content of RS (8% starch basis) was found in the PB product, compared with the remaining bread products (0.8-1.7%).

Adult↗

PubMed2000

The structure and expression of the wheat starch synthase III gene. Motifs in the expressed gene define the lineage of the starch synthase III gene family.

The endosperm of hexaploid wheat (Triticum aestivum [L.]) was shown to contain a high molecular weight starch synthase (SS) analogous to the product of the maize du1 gene, starch synthase III (SSIII; DU1). cDNA and genomic DNA sequences encoding wheat SSIII were isolated and characterized. The wheat SSIII cDNA is 5,346 bp long and contains an open reading frame that encodes a 1,628-amino acid polypeptide. A putative N-terminal transit peptide, a 436-amino acid C-terminal catalytic domain, and a central 470-amino acid SSIII-specific domain containing three regions of repeated amino acid similarity were identified in the wheat gene. A fourth region between the transit peptide and the SSIII-specific domain contains repeat motifs that are variable with respect to motif sequence and repeat number between wheat and maize. In dicots, this N-terminal region does not contain repeat motifs and is truncated. The gene encoding wheat SSIII, designated ss3, consists of 16 exons extending over 10 kb, and is located on wheat chromosome I. Expression of ss3 mRNA in wheat was detected in leaves, pre-anthesis florets, and from very early to middle stage of endosperm development. The entire N-terminal variable repeat region and the majority of the SSIII-specific domain are encoded on a single 2,703-bp exon. A gene encoding a class III SS from the Arabidopsis genome sequencing project shows a strongly conserved exon structure to the wheat ss3 gene, with the exception of the N-terminal region. The evolutionary relationships of the genes encoding monocot and dicot class III SSs are discussed.

Amino Acid Sequence↗

PubMed1970

Starch Synthesis Studies in Zea mays: II. Molecular Distribution of Radioactivity in Starch.

The amylose and amylopectin fractions from kernel starch synthesized shortly after exposure of intact Zea mays L. plants to (14)CO(2) had similar specific radioactivities (counts per min per mg of carbohydrate). In both fractions the radioactivity was distributed throughout the molecules. These data are consistent with a model in which the polysaccharides are synthesized in the matrix of the amyloplast followed by crystallization of the completed molecules onto the starch granule.

Journal Article↗