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H Weingarten

Publications and source records attributed to H Weingarten.

10 recordsLinked to original sources
PubMed2001

[Evaluation of applied kinesiology in nutritional intolerance of childhood].

BACKGROUND: Because nutritional intolerances generally are difficult to be diagnosed, Applied Kinesiology (AK) often is discussed as an alternative in this field. AIM: The uncertain scientific situation makes it necessary to assess the diagnostic value of AK. The method was compared with established laboratory tests such as RAST, lactose breath hydrogen test and a specific IgG test (Cytolisa). METHODS: 315 children and adolescents, 0-17 years old, with different chronic diseases such as headache, abdominal pain, chronic eczema, hyperactivity, and bronchial asthma were studied by means of AK for 2 years. RESULTS: We found a moderate test-retest reliability (intraclass-kappa 0.62) but no inter-tester reliability (intraclass-kappa -0.01). Moreover, there was no statistically significant agreement with either RAST and Cytolisa (sensitivity 73.6%, specificity 45.2%) or lactose breath hydrogen test (sensitivity 77.1%, specificity 43.2%). CONCLUSIONS: In general, AK cannot be recommended for diagnosing nutritional intolerance. However, due to its high sensitivity, it could be a valuable tool to give some preliminary results.

Adolescent↗
PubMed1990

Cleavage specificity of human skin type IV collagenase (gelatinase). Identification of cleavage sites in type I gelatin, with confirmation using synthetic peptides.

Type IV collagenase (gelatinase) readily cleaves denatured collagen into very small peptides. Large cyanogen bromide fragments (25 kDa) of type I collagen are degraded at the same rate as the complete alpha-chain. A number of the gelatinolytic cleavage sites of alpha 1(I)CB7 and alpha 1(I)CB8, representing 50% of the collagen alpha-chain, were determined by sequence analysis of product peptides. In addition to the expected cleavage between glycine and hydrophobic residues, several other cleavage sites were identified. These sites were Gly-Glu, Gly-Asn, and Gly-Ser. Basic residues were found adjacent to the cleavage site in several cases. Hexapeptides containing these unexpected cleavage sites were synthesized, and Km and kcat values were determined. All but one of the Km values were in the submillimolar range, and turnover numbers for the peptides uncharged at the carboxyl terminus were on the order of 10,000/h. Of particular significance was the finding that hydroxyproline occurs 5 residues from the cleavage site in all carboxyl-terminal product peptides and also occurs 5 residues from the cleavage site in seven of nine amino-terminal product peptides. A requirement for hydroxyproline may be of importance in determining the specificity of this enzyme for denatured collagenous substrates.

Amino Acid Sequence↗
PubMed1989

Cleavage specificity of type IV collagenase (gelatinase) from human skin. Use of synthetic peptides as model substrates.

Type IV collagenase (gelatinase) has a marked substrate specificity for denatured collagen (gelatin). Cleavage site specificity of type IV collagenase from human skin was determined using small collagenous peptides with varied sequences around Gly-Leu or Gly-Ile. Type IV collagenase showed essentially the same order of preference for the peptide substrates as did interstitial collagenase. Both required a peptide with a minimum of six amino acid residues to demonstrate significant gelatinolytic activity and were able to cleave uncharged molecules more rapidly than charged molecules. the repeating Gly-X-Y-Gly sequence of collagen is not an absolute requirement for either enzyme since both digested AcPro-Leu-Gly-Ile-Leu-Ala-Ala-OC2H5 at 70% of the rate of the best substrate peptide, AcPro-Leu-Gly-Leu-Leu-Gly-OC2H5. Km and kcat (Vmax) values were determined for several of the peptides and for the native substrate. Turnover numbers with type IV collagenase were similar to those with interstitial collagenase (Weingarten, H., Martin, R., and Feder, J. (1985) Biochemistry 24, 6730-6734). However, the Km for all peptides investigated was approximately 10-fold lower for type IV collagenase than for interstitial collagenase. Because type IV collagenase does not cleave helical interstitial collagens, the data support the conclusion that secondary structure determines whether the peptide bond can be hydrolyzed at any potential cleavage site.

Amino Acid Sequence↗
PubMed1989

Stimulus-induced eating when satiated.

Two studies investigated factors that promote the desire for food when people are not energy depleted. In Study 1, 20 male and female subjects, tested under conditions of either hunger or satiety, were exposed to one of two palatable foods (pizza or ice cream) and then given more of that food to eat. Operationally-satiated subjects still ate pizza or ice cream, and the sight of these foods enhanced reported desire for them. The amount of these foods consumed was predicted by the subjects' self-reported desire for the food. In Study 2, 28 male subjects were fed to satiety, then primed with either pizza or ice cream (or not primed at all) and then given both pizza and ice cream to eat. Results showed that a brief taste of a desirable food enhanced its intake relative to the other, equally-preferred food. The data are discussed in the context of the effects of priming as a form of appetite whetting. Also, it is suggested that our operations for eliciting stimulus-induced eating in sated subjects may be useful for future examinations of the psychological properties of craving.

Adolescent↗
PubMed1987

Eriochrome black T inhibition of human skin collagenase, but not gelatinase, using both protein and synthetic substrates.

The intracellular degradation of interstitial collagen is accomplished by two neutral metalloproteases, collagenase and gelatinase. Both enzymes are inhibited by metal chelating agents, by certain sulfhydryl reagents, and by similar protein inhibitors. Here, we demonstrate that the dye eriochrome black T (EBT) appears to be unique in its capacity to inhibit collagenase but not gelatinase. Using native reconstituted helical collagen in gel form at 37 degrees C, half-maximal inhibition of collagenase activity by EBT occurs at approximately 45 microM. EBT more effectively inhibits the breakdown of native collagen in solution, with a KI of approximately 8 microM. Using a newly-developed spectrophotometric substrate, AcProLeuGly-S-LeuLeuGly-OC2H5, a KI of 1.4 microM was calculated for EBT on collagenase. Although this same thiopeptolide serves as a substrate for gelatinase with kinetics similar to those of collagenase, no inhibition by EBT was observed. EBT also did not inhibit the gelatinase-mediated breakdown of the natural substrate, gelatin. The data suggest that EBT may have significant potential for allowing the differentiation in biological fluids of two metalloproteases with similar cleavage site specificities.

Azo Compounds↗
PubMed1986

Cleavage site specificity of vertebrate collagenases.

A series of synthetic peptide substrates for vertebrate collagenase having the structure Ac-Pro-Leu-Gly-X-Leu-Gly-OC2H5, where X is Leu, Ile, Val, Phe and Ala, have been prepared. Collagenolytic enzymes from various sources cleave these substrates with differing relative rate patterns. This series of peptides should be valuable for characterization of collagenases.

Amino Acid Sequence↗
PubMed1985

Synthetic substrates of vertebrate collagenase.

The active site specificity of vertebrate collagenase was mapped with the synthesis of a variety of peptides, peptolides, and peptide esters. The enzyme was found to prefer very lipophilic sequences, and it was also found to be an esterase. The thio peptolide Ac-Pro-Leu-Gly-SCH[CH2CH(CH3)2]CO-Leu-Gly-OC2H5 was found to be an exceptional substrate. High-performance liquid chromatography and tandem mass spectrometry were used to unambiguously establish the cleavage site in several peptide substrates.

Animals↗
PubMed1985

Spectrophotometric assay for vertebrate collagenase.

Collagenase from normal human skin fibroblasts was found to catalyze the hydrolysis of esters and thio esters. This observation led to the development of a rapid, sensitive, continuous spectrophotometric assay for vertebrate collagenase using the thio peptolide Ac-ProLeuGly-S-LeuLeuGly-OC2H5 as substrate in the presence of 4,4'-dithiodipyridine or Ellman's Reagent. A Km of 0.004 M and a kcat of 370,000 h-1 were determined for the thio peptolide-enzyme reaction. The method is able to detect collagenase at concentrations as low as 2 ng/ml.

Fibroblasts↗