Search PubMed⌕ Search

Biomedical subjects

H Heymann

Publications and source records attributed to H Heymann.

At least 19 recordsLinked to original sources
PubMed2000

Effect of milk fat, cocoa butter, and whey protein fat replacers on the sensory properties of lowfat and nonfat chocolate ice cream.

Lowfat and nonfat chocolate ice creams were made with 2.5% of milk fat, cocoa butter, or one of two whey protein-based fat replacers, Dairy Lo or Simplesse. Polydextrose was added as required so that all formulations contained the same amount of total solids. Ice cream was stored at a control temperature of-30 degrees C. Hardness, viscosity, and melting rate were measured by physical methods. Trained panelists conducted descriptive sensory analyses of the samples at 0, 6, and 12 wk. Attribute ratings were analyzed by analysis o variance with least significant difference mean separation and orthogonal contrasting. Data were also analyzed by multivariate analysis of variance with canonical variate analysis. Consumer acceptance (n = 50) did not differ among the fresh ice creams (wk 0). Ice cream containing milk fat had less intense cocoa flavor and was more resistant to textural changes over time compared with the other ice creams. Simplesse was more similar to milk fat than was Dairy Lo in its effect on brown color, cocoa flavor, cocoa character, and textural stability but was less similar in terms of thickness and mouthcoating.

Analysis of Variance↗
PubMed1998

Di- and oligosaccharide substrate specificities and subsite binding energies of pig intestinal glucoamylase-maltase.

The substrate specificity of pig intestinal glucoamylase-maltase was investigated. The alpha-1, beta-2-glycosidic bond of the disaccharide sucrose was not hydrolyzed. Various substrates with alpha-1,4-glycosidic bonds (maltose, maltooligosaccharides) were hydrolyzed with high maximal reaction velocities. Reduction lowered the rate of hydrolysis drastically: k'0 decreases from 75 s-1 for maltose to 3 s-1 for maltitol while the K(m) value increases from 4.2 to 50 mM. Leucrose with alpha-1,5-glycosidic bond was hydrolyzed with a k'0 value of 8 s-1 and a K(m) value of 74 mM. Disaccharides with alpha-1,6-glycosidic bonds were hydrolyzed with extremely low rates: for isomaltose and isomaltulose k'0 values of 5 and 3 s-1, respectively, and K(m) values of 90 and 42 mM, respectively, were observed. Again reduction lowers the k'0 values: The corresponding disaccharide alcohols alpha-D-glucopyranosyl-1,6-sorbitol and alpha-D-glucopyranosyl-1,6-mannitol, like isomaltooligosaccharides, were not hydrolyzed. Regarding the conformation of sucrose, leucrose, and maltose previously determined by molecular dynamics simulations, a reasonable explanation for the different rates of hydrolysis could be postulated. Based on the enzyme kinetic parameters for the series of maltooligosaccharides, subsite affinities (A1) according to the subsite theory were calculated as 7.5 (A1), 17 (A2), 3.4 (A3), and 1.3 kJ/mol (A4) for subsites 1, 2, 3, and 4, respectively. The intrinsic rate constant k'int was estimated at 76 s-1.

Animals↗
PubMed1998

Sensory and physical properties of ice creams containing milk fat or fat replacers.

The purpose of this research was to determine the relative effects of milk fat, nonfat milk solids, or each of three whey protein type fat replacers on the flavor and texture attributes of vanillin-flavored ice cream. Descriptive sensory analyses disclosed that ice creams containing 4.8% of any of the fat replacers in place of milk fat had no demonstrable effect on vanillin flavor but increased the intensities of whey flavor, syrup flavor, and cooked milk flavor. Compared with each substitute, milk fat significantly reduced the syrup, whey, and cooked milk flavors and increased the fresh milk and cream flavors of the ice cream. Results emphasized the importance of fat as a flavor modifier and the importance of certain fat replacers as aids in improving texture.

Animals↗
PubMed1997

Acarbose and 1-deoxynojirimycin inhibit maltose and maltooligosaccharide hydrolysis of human small intestinal glucoamylase-maltase in two different substrate-induced modes.

The inhibition of the glucoamylase-maltase-catalyzed maltose and maltooligosaccharide hydrolysis by acarbose and 1-deoxynojirimycin has been demonstrated. Acarbose and 1-deoxynojirimycin act as potent competitive inhibitors with Ki = 0.8 microM for the hydrolysis of maltose and with Ki values of 0.4 and 0.3 microM, respectively, for the hydrolysis of maltooligosaccharides. In a previous work (Günther et al., Arch. Biochem. Biophys. 327, 295-302, 1996) using maltitol and maltobionate as inhibitors we were able to discriminate two different binding modes for glucoamylase-maltase: a maltose and an oligosaccharide binding mode. Here we found that structurally quite different substances, namely, the pseudotetrasaccharide acarbose and the monomeric glucose analog 1-deoxynojirimycin, act as competitive inhibitors for maltose and maltooligosaccharide hydrolysis. The Ki values for all used maltooligosaccharides are nearly equal, but for maltose hydrolysis the Ki values are significantly higher by a magnitude factor of two. The differences concerning Ki values can be explained by means of the two-binding-mode model.

1-Deoxynojirimycin↗
PubMed1997

Effect of milk fat content on flavor perception of vanilla ice cream.

The effects of milk fat concentration on flavor perception of vanilla ice cream (with 0.5 to 10% fat) were studied by sensory analyses. The percentage of free vanillin in the ice cream was determined by HPLC. The HPLC data showed that the amount of free vanillin decreased when fat content increased. Perceptions of vanilla flavor and sweetness were evaluated by a trained panel using time-intensity methodology. No significant difference was found in sweetness perception. Among 11 time-intensity parameters for vanilla flavor perception, the panel found a significant difference only in the time required to reach maximum vanilla intensity. However, free-choice profiling and a consumer preference panel showed, respectively, that, as fat content was increased, sensory quality improved, and overall preference increased.

Animals↗
PubMed1996

Maltitol and maltobionate act differently on maltose- and maltooligosaccharide hydrolysis by human small intestinal glucoamylase-maltase indicating two different enzyme binding modes.

The hydrolysis of maltose and maltotriose at the same catalytic site of glucoamylase-maltase has been demonstrated. Maltitol acts as a competitive inhibitor, Ki = 69 (+/-10) mM, of the maltose hydrolysis and as a noncompetitive inhibitor of the hydrolysis of maltotriose, Ki = Kii = 29 (+/-4) mM, and maltotetraose, Ki = Kii = 30 (+/-3) mM. Maltobionate was not hydrolyzed by the enzyme and did not influence the maltose hydrolysis. In contrast, in hydrolysis of maltooligosaccharides it acts as an uncompetitive inhibitor. For the hydrolysis of maltotriose, Kii = 25(+/-8) mM, and maltotetraose, Kii = 30(+/-4) mM was found. According to a characteristic of this rare inhibition pattern a simultaneous decrease of the apparent Km and the apparent Vmax of maltooligosaccharide hydrolysis with increasing maltobionate concentrations was observed. We were able to discriminate two different binding modes for glucoamylase-maltase. Maltitol binds to the free enzyme (maltose binding mode) as well as to the maltooligosaccharide-enzyme complex, whereas maltobionate binds only to the oligosaccharide-enzyme complex (oligosaccharide binding mode). This could be shown by the different inhibition behaviors of maltitol and maltobionate depending on the substrate: maltose or maltooligosaccharides.

Binding Sites↗
PubMed1995

Human small intestinal sucrase-isomaltase: different binding patterns for malto- and isomaltooligosaccharides.

The hydrolysis of maltose and isomaltose and of sucrose and isomaltose at two different catalytic sites of sucrase-isomaltase has been demonstrated. Maltose and sucrose are competing for the same catalytic center. This competing can be described by alternative substrate kinetics. Steady-state kinetic parameters Km and k0 (maximal reaction velocity per mol enzyme) for linear alpha-1,4 and alpha-1,6 glucosyloligosaccharides has been determined. Using these parameters subsite affinities for the catalytic sites of sucrase and isomaltase were computed. The different numbers of subsites for sucrase (2 subsites) and isomaltase (4 subsites) indicate, that the binding patterns for maltooligosaccharides and isomaltooligosaccharides are different. That means that for sucrase unproductive enzyme-maltooligosaccharide complexes are definitely less probable than the productive one. As in human small intestinal glucoamylase-maltase in the isomaltase moiety four subsites can be evaluated with affinity values (Ai): A1 = 2.6 (+/- 0.91), A2 = 13.8 (+/- 0.70), A3 = 1.1 (+/- 0.13) and A4 = 1.5 (+/- 0.13) kJ/mol using isomaltooligosaccharides. The two subsites of sucrase are evaluated to be A1 = 4.9 (+/- 0.70) and A2 = 16.7 (+/- 0.51) kJ/mol using maltooligosaccharides. The four subsite model for isomaltase and glucoamylase-maltase is an indication that these two enzymes are mechanistically homologous in binding linear glucosyl-oligosaccharides.

Catalysis↗
PubMed1994

[Results of surgical management of unstable pertrochanteric femoral fractures with the dynamic hip screw and T-plate].

The dynamic hip screw (DHS) is a widely used method of osteosynthesis. Nevertheless, supplying instable pertrochanteric fractures is problematic because the gliding screw may cause a considerable dislocation of fragments in lateral direction. Is there any alternative method disposable, bearing stability of DHS- osteosynthesis can be improved by adding a lateral T-plate. We reached full bearing stability in four cases.

Aged↗
PubMed1994

Calculation of subsite affinities of human small intestinal glucoamylase-maltase.

Several years ago, Hiromi et al. (1973) Biochim. Biophys. Acta 302, 362-375 proposed a theory for the action patterns of glucoamylases, based on data from steady-state kinetics. The Michaelis-Menten constants (Km) and the turnover number for maltooligosaccharides were used to evaluate the subsite affinities. We have now used this method for evaluating the subsite affinities for glucoamylases(EC 3.2.1.3)-maltase (EC 3.2.1.20) from human intestinal mucosa. For calculation of the subsite affinities, A1 and A2, and the intrinsic rate constant kint, we use a modified algorithm and a computer program for nonlinear least square fitting. Considerable substrate inhibition was shown by maltotriose, minor inhibition by maltotetraose, and no inhibition by maltose and the other maltooligosaccharides. This indicates a more complex kinetic behaviour of the enzyme with respect to maltotriose. Evaluation of the subsites reveals that A2 is the main binding site (18.1 kJ/mol), whereas the other affinities, with the exception of A1, are lower than 2.5 kJ/mol.

Glucan 1,4-alpha-Glucosidase↗
PubMed1993

Improving survival of culture bacteria in frozen desserts by microentrapment.

Lactobacillus bulgaricus cells were entrapped in beads of calcium alginate and evaluated for their ability to survive freezing processes. Cells survived freezing (without agitation) in ice milk mix much better than in distilled water, and more entrapped cells survived than did cells that were not entrapped. Glycerol and mannitol were cryoprotective, but glucose was not, when each was added (6%) separately to the beads. Entrapment protected the lactobacilli in batch frozen and continuously frozen ice milk mixes. The percentage of survival for entrapped and unentrapped cells in continuously frozen ice milk approximated 90 and 40%, respectively. Lactobacilli survived better in beads with mean diameters > 30 microns than in those averaging 15 microns. Addition of entrapped lactobacilli had no measurable effect on the sensory characteristics of the ice milk.

Alginates↗
PubMed1992

[Cemented bipolar prosthesis in multimorbidity patients with coxarthrosis. Short- and intermediate-term results].

The treatment of coxarthrosis with the cemented Duopleet prosthesis represents an efficient alternative to total hip prosthesis in elderly and polymorbid patients. The early results show a tolerable rate of complications. The patients can be mobilized early. The mortality seems to be low. Medium-term results are satisfactory. The rate of protrusions is lower than in patients with common femoral head prosthesis. Paraarticular ossifications are seen frequently. In numerous patients we found pain with projection to the operated hip.

Aged↗
PubMed1992

[Ender nailing versus dynamic hip screw--a comparison of early postoperative results].

Proximal fractures of femur may be alternatively treated by implantation of dynamic hip screws or Ender-nails. Estimation of the value of both measures is to be done by analysis of the early postoperative course. Full load bearing capability was obtained in 83% of all cases with Ender-nails as against 68% of all cases after implantation of hip screws. Duration of operation was clearly shorter and the need for blood transfusions was reduced by implantation of Ender-nails. The amount of specific technical complications was equal in both procedures. There were no differences in the postoperative ability to walk.

Aged↗
PubMed1991

[Results of cryosurgery in the treatment of inoperable tumor stenoses of the anus and rectum].

Inoperable tumor stenosis of anus and rectum may be treated surgically only by implantation of artificial anus. Cryosurgery proves to be a feasible alternative in order to maintain free passage of the gut. The cryoprobe is introduced through a rectoscopy under direct view. Visible tumor is touched with the tip of the cryoprobe and subsequently temperature is lowered to approximately -19 degrees C. Usually anesthesia is not required. From 1976 to 1989, 213 patients had been treated by cryosurgery in our department. In 23 cases the use of an artificial anus became inevitable afterwards.

Anus Neoplasms↗
PubMed1991

[The value of serum endotoxin determination after gastrointestinal interventions].

Serumendotoxins were measured in 11 patients after gut surgery and compared with healthy people as a standard. In cases of uncomplicated course 3 to 4-fold raised serumendotoxin levels were observed in a typical two-peak pattern. It was not before the fifth day following operation that serum levels declined constantly. In contrast to these findings, patients suffering from septic complications showed a permanently raised endotoxin level, which correlated well with their clinical course. Therefore single peaks of serumendotoxin measured after operation should not be overvalued. Constantly raised levels following operation, however, may indicate some kind of septic complication.

Aged↗
PubMed1990

[Insulinoma. Results of surgical treatment].

The insulinoma is the most common pancreas tumour with endocrine activity, with more than 2,000 cases being described in the literature worldwide. The first successful extirpation was performed by Graham in 1928. Clinical appearance is characterized by severe paroxysmal hypoglycaemia together with inadequately increased serum insulin levels. Surgery is indicated in such situations because of limited effectiveness of medicamentous therapy. Surgical approach and long-time results are discussed in this paper, with reference being made to 13 cases of the authors.

Adenoma, Islet Cell↗
PubMed1989

The serum activities of AP, gamma-GT, GLDH, GPT and CHE after complete biliary obstruction and choledochocaval fistula in the rat.

The activities in serum of alkaline phosphatase, gamma-glutamyltransferase, glutamate dehydrogenase, glutamic pyruvic transaminase and cholinesterase were compared after complete biliary obstruction (CBO) and choledochocaval fistula (CCF) in the rat. CCF was used as a model of complete biliary retention without bile stasis and without increased pressure in the biliary tract. The increases in AP, GLDH and gamma-GT within 24-h post-op. show no difference between the two experimental groups. The conclusion is that the retention of biliary constituents alone is responsible for the increase in the levels of serum activity and that other conditions like bile stasis and increased pressure in the biliary tract do not play an important role in the pathogenesis of these alterations. The rise of GPT activity in CCF is of a lesser degree than in CBO.

Alanine Transaminase↗
PubMed1989

Effect of fasting and transportation on various physiological parameters and meat quality of slaughter hogs.

Forty-nine slaughter hogs were transported and fasted or fasted with no transport for 0 (no transport), 24, 48 and 72 h. Blood samples were taken before treatments were imposed and again prior to slaughter. Soft tissues of the ham were chemically analyzed and loin samples were evaluated by a sensory panel. Fasting and transportation decreased plasma triiodothyronine and hematocrit and increased plasma osmolality. Preslaughter treatment did not affect juiciness or desirability of cooked chops or percentage of fat in the ham soft tissues. These data suggest that although fasting and transporting of slaughter hogs may disrupt homeostasis of pigs, such physiological changes do not negatively affect meat quality.

Animals↗