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PubMedDate not supplied

[Activity of carbohydrate-metabolizing enzymes and content of carbohydrate and nitrogen compounds in muscles of young cattle depending on breed and sex].

The activity of glycolysis and glyconeogenesis enzymes, content of carbohydrate and nitrogen compounds were studied in muscles of 15-month cattle of different sex of the black-piebald breed and its crosses with bulls of two meat breeds Hereford and Limousine. In the muscles of bulls the activity of phosphoglucomutase, phosphohexoisomerase, aldolase and fructose-1,6-diphosphatase is considerably higher (except of the activity of phosphoglucomutase and phosphohexoisomerase in the muscles of pure-bred black-piebald animals for which difference is not statistically reliable) and the content of glycogen, glucose, fructose, lactic acid, free and phosphorylated pentoses of nonadenylic compounds is essentially lower than in the muscle tissue of heifers of analogous breed groups. A higher activity of carbohydrate metabolism enzymes (especially aldolase and fructose-1,6-diphosphate) and a higher content of total pentoses, the adenylic system pentoses, ATP phosphorus in the muscles of the cross Limousine and Hereford bulls and Limousine heifers as compared to the pure-bred black-piebald animals of the corresponding sex coincide with a greater increase in the muscular tissue and more intensive synthesis of proteins in it. A considerably lower level of glycogen, glucose, fructose and a relatively high activity of carbohydrate metabolism enzymes in the muscles of cross young cattle show that disintegration of these carbohydrates is in excess of their synthesis, that is due to an increase in the energy demand connected with a more intensive synthesis of proteins in the muscular tissue. Therefore, in the authors opinion the performed kill of the cross Limousine and Hereford bulls as well as Limousine heifers, is somewhat untimely and unreasonable. At the same time the activity of all the studied enzymes in the muscles of the cross Hereford heifers, vice versa, is considerably lower as compared to the black-piebald heifers and coincides with a low gain in live weight and muscular tissue, a more rapid accumulation of glycogen and lipids and a more delayed--of proteins in the muscular tissue, that evidences for their early maturity. Therefore the further raising of the cross Hereford heifers in the farm for obtaining meat is economically less profitable. The data obtained give grounds to recommend determination of the activity of carbohydrate metabolism enzymes, especially of aldolase and fructose-1,6-diphosphate, as a test for checking the muscular tissue growth and for prognosing the meat productivity in the growing pure-bred and cross young cattle of different sex.

Adenosine Triphosphate↗
PubMed1979

Carbohydrate inhibitors of concanavalin A that inhibit binding of insulin-sepharose to fat cells and antagonize and mimic insulin's bioactivity. A possible role for membrane carbohydrate in insulin's action.

A consistent pattern of insulin-like properties is expressed by a variety of glycoside inhibitors of concanavalin A (Con A), and is suggestive of a common mechanism of action to explain these effects. Various exogenously added glycoside derivatives inhibit the binding of insulin-Sepharose beads to insulin receptors on isolated intact rat fat cells with a specificity resembling that for Con A-Sepharose binding to these cells. A more limited number of glycosides tested were also found to inhibit the binding of 125I-insulin, although some enhancement of binding that preceded the inhibition was observed for some of these saccharides. The glycosides also antagonize insulin-stimulated glucose utilization by the cells, but in some cases also mimic the hormone by stimulating glucose utilization. A few glycosides mimic insulin without appearing to antagonize its bioactivity. Radiolabeled glycoside inhibitors fail to bind to insulin in equilibrium dialysis experiments although they readily bind to Con A, indicating that the glycosides act directly on the cell rather than on the insulin molecule. The latter observation is consistent with the ability of those glycosides that act like insulin to do so independent of the hormone. In view of the known insulin-like properties of Con A, the effects of the glycosides seen in the present study suggest roles for a membrane carbohydrate and a carbohydrate binding site in the mechanisms of action of both insulin and Con A. In addition to various alternative explanations, a working hypothesis is presented to rationalize the present observations. It proposes that the effects of the exogenously added glycosides (and Con A) may reflect the presence on the membrane of a native carbohydrate moiety by either mimicking or competitively inhibiting its ability to interact reversibly with a lectin-like carbohydrate binding site associated with the function of the insulin receptor.20

Adipose Tissue↗
PubMedDate not supplied

[Various changes in carbohydrate and lipid metabolism and the state of the islands of Langerhans in female rabbits after long-term feeding with food rich in carbohydrates and ovariectomy].

Experiments were conducted on 21 female rabbits. Prolonged excessive feeding with food rich in readily assimilated carbohydrates (bisquits) started at immature age caused hypertrophy and hyperplasia of the insular apparatus of the pancreas, particularly in ovariectomy. The average blood sugar level on fasting stomach displayed a significant reduction in ovariectomized female rabbits. Some female rabbits displayed signs of "exhaustion" of beta-cells of the islets of the pancreas, with the development of latent diabetes mellitus in one of them. Prolonged excessive feeding with food rich in readily assimilated carbohydrates led to the intensification of atherogenesis, most pronounced in the animals with signs of "exhaustion" of beta-cells of the islets of the pancreas.

Animals↗
PubMed1979

Periodate oxidation analysis of carbohydrates. XIII. Simultaneous gas chromatographic determination of the aldehydes in the periodate oxidation products of non-dialyzable urinary carbohydrate materials as diethyl dithioacetals.

The aldehydes in the periodate oxidation products of non-dialyzable urinary carbohydrate materials were determined simultaneously by gas chromatography of their diethyl dithioacetal derivatives. The yields of aldehydes for normal male urine varied considerably among subjects, but their molar ratios were almost constant. The average values for glyceraldehyde/glyoxal and lactaldehyde/glyoxal molar ratios were 0.41 and 0.27, respectively. The average amount of L-fucose at the non-reducing terminals of carbohydrate chains, as estimated from the yield of lactaldehyde, was about 5 mg/day.

Aldehydes↗
PubMed1979

[Carbohydrate-reduced diet and metabolism: about the influence of a 4-weeks isocaloric fat-rich, carbohydrate-reduced diet on body weight and metabolism (author's transl)].

The influence of a 4-weeks carbohydrate-reduced, fat-rich diet on 9 slightly overweighted men was investigated. Caloric and protein intake remained unchanged. 70% were fat, 20% carbohydrates. Glucose, cholesterol, triglycerids, serumproteins, urea, uric acid, sodium and potassium were measured in rest. At a 60 minutes bicycle ergometer test glucose, triglycerids, free fatty acids and glycerol were registrated before and after 20 and 60 minutes work. The intensity was 70% of the maximal oxygen uptake. These were the most important results: (1) Body weight decreased continuously. One of the causes is an elevated heat production. (2) Serum-protein and -glucose remained unchanged. Cholesterol and triglycerides were reduced. Serum-urea, -sodium and -potassium diminished continually. On the contrary, uric acid raised over the normal range. (3) Work performance was reduced for 20%. (4) Hypoglycemic values did not appear. The oxidation of fat by the working muscles, and fat mobilisation increased by a fat-rich diet.

Adult↗
PubMed1975

Possible intervention of insulin, cyclic AMP, and glucocorticoids in protein-sparing action of dietary carbohydrate in rats.

The present study was carried out to examine the possible intervention of some hormones in the "protein-sparing/actions of dietary carbohydrate and fat. Administration of either a carbohydrate meal or a fat meal to fasted rats caused a reduction in the urinary output of urea and total nitrogen with a concomitant decrease in rate of urogenesis in liver. as well as the activities of some amino acid-catabolizing enzymes in liver. The sparing action of carbohydrate but not that of fat was abolished in alloxan-diabetic rats. Feeding rats a carbohydrate meal caused a marked reduction in the amount of cyclic AMP in liver. The change was coincident with a reduction in the level of plasma urea and the urinary output of urea and total nitorgen. Administration of dibutyryl cyclic AMP abolished the carbohydrate-induced depression of urinary output of urea and total nitrogen as well as partially the activity of serine dehydratase in liver. Feeding a carbohydrate meal resulted in a significant reduction in the level of corticosterone in plasma. However, the possible intervention of glucocorticoids in the protein-sparing action of carbohydrate was ruled out inasmuch as the action of carbohydrate was also observed in the adrenalectomized rats. The overall results suggest that the protein-sparing action of dietary carbohydrate may be exerted in a different fashion from that of fat, that is, through depression of cyclic AMP in liver and thus the reduction of the degradation of amino acids in liver

Adrenal Glands↗
PubMed1975

Immunochemical and chemical studies on streptococcal group-specific carbohydrates.

Structural studies on the carbohydrates of Groups A, C, and A-variant (AV) streptococci have utilized periodate oxidation, permethylation analysis, and immunochemical comparison of intact and periodate-oxidized polysaccharides. The data indicate that a similar 1,2- and 1,3-linked rhamnose chain is present in both the A and AV carbohydrates. The group A carbohydrate contains in addition N-acetylglucosamine residues at nonreducing terminals, whereas the AV is a homopolymer of rhamnose. There is some evidence that Group Ccarbohydrate contains the same rhamnose chain, but structural comparisons to the A and AV carbohydrates are complicated by the presence of intrachain N-acetylgalactosamine residues. Periodate oxidation and permethylation analysis show that while approximately 50% of the N-acetylgalactosamine of the Group C carbohydrate occupies terminal positions, the remainder is present as 1,3-linked units. Removal of the nonreducing terminal hexosamine units from the Group A carbohydrate by periodate treatment significantly enhanced its cross-reactivity with AV antiserum, whereas no enhancement was observed after similar treatment of the Group C carbohydrate. The data indicate the presence of an alpha-1,3-linked N-acetylgalactosamine disaccharide at the nonreducing terminal of the Group C carbohydrate.

Amino Acids↗
PubMed2026

Hybrid genome assembly and phenotypic assays reveal carbohydrate metabolism diversity in Lacticaseibacillus strains.

Investigation of carbohydrate metabolism in lactic acid bacteria is essential for the rational selection of strains for fermentation processes, particularly in emerging applications involving non-conventional substrates or building of synthetic microbial consortia. However, establishing robust genotype-phenotype relationships remains challenging, as gene presence alone often fails to explain observed metabolic traits without considering the genomic context and regulatory architecture. In the present study, we combined hybrid genome assembly (Illumina and Oxford Nanopore) with high-throughput phenotype profiling (Biolog GENIII and PM2A) to investigate carbohydrate utilization in five Lacticaseibacillus strains. Phenotypic assays revealed clear intra- and inter-specific variability in substrate utilization. We therefore investigated whether such differences could be attributed to the organization and regulatory context of carbohydrate-associated loci, rather than to gene presence alone. Functional annotation based on COG and CAZyme databases revealed candidate genomic regions potentially involved in carbohydrate metabolism. Comparative analysis between predicted and experimentally observed substrate usage highlighted specific loci associated with carbohydrate utilization profile. The trehalose (tre) operon was conserved across all strains, while at least two distinct cellobiose-associated loci were detected in each genome. Despite the presence of these loci, L. paracasei strains were unable to metabolize cellobiose, a phenotype likely linked to the presence of a downstream TetR-type transcriptional repressor within the cellobiose (cel) operon. Additionally, a genomic region uniquely found in L. rhamnosus strains was associated with gentiobiose utilization, consistent with phenotypic observations. Overall, these findings highlight the importance of integrating phenotypic validation with complete genome context to support the identification of candidate structural and regulatory determinants of carbohydrate utilization in lactic acid bacteria. KEY POINTS: • Phenotype microarrays reveal metabolic traits of interest in isolated strains. • Regulatory context is key to understanding carbohydrate metabolism differences. • Basis of subspecies-dependent cellobiose metabolism in L. paracasei is provided.

Carbohydrate Metabolism↗
PubMed1979

Dietetic treatment of obesity with low and high-carbohydrate diets: comparative studies and clinical results.

In spite of numerous studies in the literature, it is still questionable as to whether the isocaloric exchange of carbohydrate and fat, in the form of a diet, leads to different degrees of weight loss. In comparative studies, obese patients given a low-carbohydrate (4.14 MJ [1000 kcal]) formula diet (diet Ia) lost 14.0 +/- 1.4 kg and those given an iso-energetic high-carbohydrate diet (diet Ib) 9.8 +/- 0.9 kg. The degree of weight loss was significantly different. Daily weight losses were 362 g and 298 g respectively. Comparative studies of high and low-carbohydrate (7.83 MJ [1900 kcal]) formula diets (diets IIa and b) with a greater number of calories did not show any significant difference. However, there was a greater mean weight loss with the low-carbohydrate diet (351 g/day) compared with that under the high-carbohydrate diet (296 g/day). Evaluation of 117 patients treated with formula diets resulted in a weight loss of over 9 kg in 102 obese patients and over 18 kg in 52 patients. The good response to the low-carbohydrate diet was partly responsible for the successful therapy.

Adult↗
PubMed2026

Dietary approaches for glycemic management in type 1 diabetes: A systematic review of Mediterranean and low-carbohydrate diets.

BACKGROUND/OBJECTIVES: Specific dietary approaches for better management of type 1 diabetes (T1D) have not been thoroughly investigated. We conducted a systematic review to evaluate the Mediterranean and low-carbohydrate diets for glycemic management in people with T1D. METHODS: We examined longitudinal studies (cohort studies and clinical trials) including individuals with T1D who followed low-carbohydrate diets (<26% calories from carbohydrates and/or <130&#x202f;g of carbohydrates per day) and/or a Mediterranean diet, while hemoglobin A1c (HbA1c) and/or time in range (TIR) were measured. Additional eligibility criteria included publication in English and availability of a full-text primary research article. Non-longitudinal studies, abstracts, and studies published in languages other than English were excluded. Results were synthesized narratively, and the GRADEpro Guideline Development Tool was used to assess article quality. RESULTS: A total of 565 studies were identified from PubMed, the Web of Science, and citation chasing. After removal of duplicates and further evaluation, 22 studies (6 cohort studies and 16 clinical trials; total n&#x202f;=&#x202f;3284) were included in this review. The search was initially completed in May 2024, and updated February 2026. Low-carbohydrate diets were associated with better glycemic management when compared to usual diets or baseline glycemic parameters. Studies using CGM were overall underpowered. The impact of Mediterranean diets was less clear, but generally appeared to be less effective at improving glycemic management than low-carbohydrate diets. DISCUSSION: Although structured dietary interventions for T1D hold promise for improving glycemic outcomes, further research is needed to determine exactly which dietary intervention is most beneficial for this population. The evidence provided by included studies is limited by small sample sizes and short durations; better powered, longer-term studies are required to inform clinical recommendations.

Humans↗
PubMed2026

Low Carbohydrate Availability in Energy Balance Alters Bone Turnover and Muscle Proteomic Response With Limited Endocrine Disruption.

Training with low carbohydrate availability (LCA) has been proposed as an independent determinant of physiological perturbations commonly attributed to low energy availability (LEA) and to increase skeletal muscle oxidative machinery, yet the effects of LCA in isolation from LEA remain unclear. We examined whether short-term carbohydrate restriction under energy balance alters endocrine and metabolic markers associated with LEA and skeletal muscle proteomic response. In a randomized crossover design, eight trained males completed 4&#x2009;days of either a low-carbohydrate high-fat diet (LOW; 12% carbohydrate, 69% fat, 19% protein) or a normal-carbohydrate diet (NORM; 62% carbohydrate, 19% fat, 19% protein), while undertaking daily cycloergometer exercise (15&#x2009;kcal kg FFM-1 day-1) and maintaining energy availability at 45&#x2009;kcal kg FFM-1 day-1. LOW induced a clear metabolic shift consistent with LCA, evidenced by elevated circulating free fatty acids, glycerol and &#x3b2;-hydroxybutyrate, in fasting conditions and fat oxidation at rest and during exercise, alongside reduced exercise glucose concentrations. Despite these responses, LOW did not alter insulin, testosterone, triiodothyronine, leptin, hepcidin, or P1NP. In contrast, &#x3b2;-CTX increased and IGF-1 decreased relative to NORM. Muscle glycogen concentration decreased only in LOW (40%&#x2009;&#xb1;&#x2009;14%). Proteomic analysis identified 671 proteins; 57 differentially expressed in LOW relative to NORM were limited to fatty acid metabolism pathways and suppression of ribosomal, sarcomeric, and extracellular matrix proteins. These findings indicate that isolated LCA exerts limited endocrine disruption but may selectively compromise bone turnover and muscle anabolic response, suggesting that without acute LEA, LCA has limited influence on muscle oxidative phenotype.

Male↗
PubMed1979

Effects of differences in amount and kind of dietary carbohydrate on plasma glucose and insulin responses in man.

The effect of variations in kind and amount of dietary carbohydrate on plasma glucose and insulin responses was studied in normal subjects and in patients with chemical diabetes. Plasma glucose and insulin responses fell when the proportion of total calories given as carbohydrate were decreased by 15% (coincidental with a comparable increase in dietary fat). Associated with the lower plasma glucose and insulin concentrations was a fall in fasting and postprandial triglyceride levels. Plasma glucose and insulin responses were also lower when equivalent carbohydrate challenges were given as part of a mixed meal, as compared to a drink. Furthermore, carbohydrate given as starch also led to an attenuated glucose and insulin response when compared to an equivalent amount of glucose administered as either dextrose or sucrose. Finally, significant differences were also seen after the ingestion of different kinds of starch, with potato being the most like dextrose, and rice the least. These results indicate that differences in amount and kind of ingested carbohydrate can modify ensuing plasma glucose and insulin responses, and raise the possibility that such dietary manipulation may have some therapeutic utility in patients with abnormal carbohydrate and lipid metabolism.

Blood Glucose↗
PubMed1976

Protein-carbohydrate-lipid complex isolated from the cell envelopes of Chlamydia psittaci in alkaline buffer and ethylenediaminetetraacetate.

Exposure of isolated cell envelopes from purified infectious elementary (EB) of Chlamydia psittaci to sodium carbonate-bicarbonate buffer at pH 10 plus ethylenediaminetetraacetate (EDTA) results in partial solubilization of the total protein. The released materials represent 20% of the dry weight, 16% of the total protein, 40% of the total carbohydrate, and 9% of the total lipid of the cell envelopes. Sucrose density gradient centrifugation, and Sephadex G-200, Sepharose 4B, or diethylaminoethyl-cellulose column chromatography, reveal a protein-carbohydrate-lipid complex of several hundred thousand molecular weight that contains 50% protein. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the isolated EB cell envelopes reveals two major protein bands, A and B, with estimated molecular masses of approximately 85,000 and 53,000, respectively, both of which also stain for the presence of carbohydrate and lipid. Gel electrophoresis of the protein-carbohydrate-lipid complex reveals two protein bands, C and D, with estimated molecular weights of approximately 17,000 and 13,000, respectively, which contain lipid and a small amount of carbohydrate; bands A and B are not present in the complex. Gel electrophoresis of the cell envelope residues after extraction of the complex with alkali and EDTA shows a single main band, corresponding to the position of band B, which contains protein, carbohydrate, and lipid; band A is completely missing. B and A is believed to be a component of the complex, which is split into two subunits on alkali solubilization.

Bacterial Proteins↗
PubMed1978

Subclass restriction of murine anti-carbohydrate antibodies.

Examination of the subclass distribution of murine antibodies directed against groups A and C streptococcal carbohydrate, alpha-(1 leads to 3) dextran and phosphocholine yields the surprising observation that these carbohydrate antigens stimulate IgG responses largely restricted to the rare IgG3 subclass. This subclass restriction is particularly impressive in light of the low circulating levels of IgG3 in nonimmune mouse serum and the failure of a variety of other antigens including proteins and aromatic haptens to stimulate IgG3 antibody production. Attempts to alter the subclass restriction of antibodies with carbohydrate specificity by immunization with carbohydrate-coupled protein have been unsuccessful and indicate that immunoregulation of subclass expression probably occurs at the level of the antibody forming (B) cell. It is therefore conceivable that VH regions of murine immunoglobulins may be restricted to particular IgG subclasses. A similar type of subclass restriction has been reported in human and rat anti-carbohydrate antibodies. This recruitment of a minor immunoglobulin isotype by carbohydrate antigens in several species further supports the concept of immunoregulation at the level of subclass, and suggests that these and other mammals may share a structurally similar isotype with perhaps a common evolutionary origin.

Animals↗
PubMed1978

Nonsecreting myeloma variants with heavy-chain carbohydrate deficiencies.

Light- and heavy-chain synthesis was studied in six previously isolated S194-2 mouse myeloma variant lines and in the parent from which they were derived. Serological data and comparative analysis of the cyanogen bromide fragments obtained from variant and parent intracellular immunoglobulin showed that five variants which failed to secrete detectable amounts of IgA synthesized both heavy- and light-chain subunits. Whereas at least two heavy-chain populations were resolved in the parent line, one containing carbohydrate and one devoid of carbohydrate, only the heavy-chain fraction devoid of carbohydrate was detected in the variant lines. The correlation between carbohydrate deficiencies on the heavy chains and lack of immunoglobulin secretion in five independent subclones is discussed in terms of possible primary lesions and the role of carbohydrate in secretion.

Carbohydrate Metabolism↗