Effect of age and dietary histidine on histamine metabolism of the growing chick

Causal associations of histidine and 12 site-specific cancers: a bidirectional Mendelian randomization study

An increasing number of studies indicate that cancer patients' histidine (HIS) circulating levels have changed. However, the causality between HIS and cancer is still not well established. Thus, to ascertain the causal link between HIS and cancers, we performed a bidirectional Mendelian randomization (MR) analysis. Summary-level data are derived from publicly available genome-wide association studies (GWAS). The causal effects were mainly estimated using the inverse-variance weighted method (IVW). The weighted-median (WM) method and MR-Egger regression were conducted as sensitivity analyses. In the forward-MR, we found malignant neoplasm of respiratory system and intrathoracic organs (OR: 1.020; 95% CI: 1.006-1.035; pIVW = 0.007) genetically associated with circulating HIS. And there was no significant genetic correlation between HIS and another 11 site-specific cancers using IVW method. In the reversed-MR, we did not observe the causal relationship between HIS and 12 site-specific cancers. Our findings help clarify that HIS, as a biomarker for malignant neoplasms of respiratory system and intrathoracic organs, is causal rather than a secondary biomarker of the cancerous progression. The mechanism between histidine and cancer progression deserves further investigation.

Potential Benefits and Pitfalls of Histidine Supplementation for Cancer Therapy Enhancement

Dietary supplementation of the amino acid histidine has demonstrable benefits in various clinical conditions. Recent work in a pediatric leukemia mouse model exposed a surprising potential application of histidine supplementation for cancer therapy enhancement. These findings demand a deeper reassessment of the physiological effects and potential drawbacks of histidine supplementation. As pertinent to this question, we discuss the safety of high doses of histidine and its relevant metabolic fates in the human body. We refrain from recommendations or final conclusions because comprehensive preclinical evidence for safety and efficacy of histidine supplementation is still lacking. However, we emphasize the incentive to study the safety of histidine supplementation and its potential to improve the clinical outcome of pediatric blood cancers through a simple dietary supplementation. The need for comprehensive preclinical testing of histidine supplementation in healthy and tumor-bearing mice is fundamental, and we hope that this review will facilitate such studies.

Safety and efficacy of l-histidine monohydrochloride monohydrate produced by fermentation with Escherichia coli (NITE BP-02526) for all animal species

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on l-histidine monohydrochloride monohydrate produced by fermentation with Escherichia coli (NITE BP-02526) when used as a nutritional additive or as a feed flavouring compound in feed and water for drinking for all animal species. The product under assessment is l-histidine HCl H2O produced by fermentation with a genetically modified strain of E. coli (NITE BP-02526). The production strain and its recombinant DNA were not detected in the final products. l-Histidine HCl H2O does not give rise to any safety concern to the production strain. The use of l-histidine HCl H2O is safe for the target species when used to supplement the diet in appropriate amounts. It is safe at the proposed use level of 25 mg/kg when used as a flavouring compound for all animal species. The use of l-histidine HCl H2O in animal nutrition raises no safety concerns for consumers of animal products. The additive is not irritating to the skin or eyes and is not a skin sensitiser. There is a risk for persons handling the additive from the exposure to endotoxins by inhalation. The use of l-histidine as a feed additive does not represent a risk to the environment. The additive l-histidine HCl H2O is regarded as an effective source of the amino acid l-histidine when used as a nutritional additive. For the supplemental l-histidine to be as efficacious in ruminants as in non-ruminant species, it requires protection against degradation in the rumen. It is also considered efficacious as a feed flavouring compound under the proposed conditions of use.

From Tryptophan to Hydroxytryptophan: Reflections on a Busy Life

Given the very difficult odyssey of my early years, who could have imagined the incredible and successful journey that constituted my life path after age 13? I was born into a Jewish family in Breslau, Germany, right before the rise of Nazism and Hitler's election. After Kristallnacht, when my father was taken to Buchenwald Concentration Camp, we had to leave Germany as soon as possible. The first opportunity came in May of 1939, when we boarded the SS St. Louis bound for Havana, Cuba. Almost all passengers were denied entrance into Cuba, and the ship had to go back to Europe, where I ended up in France. In December of 1939, during World War II, I was fortunate to be able to leave France. This time I made it to Cuba, where my father was already in residence. A year later, my entire family was allowed into the United States. I took advantage of all the educational resources in this land of opportunity. I graduated valedictorian of my high school class and earned a four-year scholarship to Rutgers University, where I obtained a Bachelor of Science degree. I went on to earn a Master's degree from the University of Connecticut and finally a PhD from the University of Illinois. Within two months after graduating from Illinois, I was hired as an assistant professor of nutritional biochemistry at Rutgers, where I enjoyed a most productive research and teaching career. My PhD research involved tryptophan and niacin metabolism in the chick, and upon arrival at Rutgers I continued amino acid studies with the goal of assessing the essential amino acid requirements for egg production. This research was crowned with success and was followed with amino acid requirement studies for maintenance and for growth in rabbits, and ultimately with a reevaluation of requirements in adult humans. An outgrowth of the maintenance requirements led to a series of investigations into the metabolism of histidine, histamine, and carnosine (a histidine-containing dipeptide). Histamine, we found, plays an important role in wound healing and stress management. Pyridoxal phosphate is the cofactor for the enzyme histidine decarboxylase required for histamine synthesis and similarly serves as a cofactor for hydroxytryptophan decarboxylase, the enzyme that is part of the pathway to serotonin synthesis. Investigations into these pathways led to interesting findings: brain concentrations of serotonin could be increased by supplementing the diet of rats with tryptophan and pyridoxine; the elevated brain serotonin levels had behavioral consequences. Alcohol craving, addiction, and withdrawal symptoms are affected by serotonin concentrations in the brain, and alleviation of these conditions can be achieved with simultaneous administration of serotonin and dopamine agonists. In the midst of our early amino acid studies, we serendipitously also became involved with lipid metabolism in relation to atherosclerosis and blood cholesterol in a chicken model. This work led to the recognition that soluble fibers, like pectin, had strong cholesterol-lowering properties that were beneficial in lowering the incidence of coronary plaque formation. The research success that I have enjoyed has been coupled with the gift of three accomplished children who are making important contributions as professionals in their fields of endeavor. My wife and I are also blessed with 10 wonderful grandchildren, our pride and joy!

Regional distribution of histamine in the brain of non-mammalian vertebrates

The histamine contents in the brains of various species of non-mammalian vertebrates were determined by an HPLC-fluorometric method. The whole brain contents of histamine in birds (200-500 pmoles/g) were comparable to those in mammals, but were higher in reptiles (1000-13500 pmoles/g) and amphibia (1600-2200 pmoles/g) and lower in teleosts (10-50 pmoles/g). In all species, histamine was unevenly distributed, being present at highest concentrations in the diencephalon, except in teleosts, in which its content was highest in the telencephalon. The brain histamine contents were proportional to the reported densities of histamine-immunoreactive fibers.

Dietary pyridoxine interaction with tryptophan or histidine on brain serotonin and histamine metabolism

We studied the metabolic effects of high dietary intakes of pyridoxine and of the substrate-cofactor interaction between dietary histidine or tryptophan and pyridoxine in rat brain. In the substrate-cofactor interaction study, histamine and serotonin levels were determined in rats fed elevated or requirement levels of substrate (histidine: 0.3% and 0.8%, tryptophan: 0.15% and 0.6%) and excess or requirement levels of pyridoxine HCl (7 mg vs. 3,000 mg/kg). Excess pyridoxine intake caused a differential effect on brain histamine concentration--inhibitory with the requirement level of histidine (-29%), and stimulatory (+21%) with the elevated level of histidine. When dietary tryptophan was fed at the requirement level, excess pyridoxine caused essentially no changes in hypothalamic serotonin and 5HIAA (-2%, -2%). With elevated tryptophan intake, excess pyridoxine significantly increased serotonin and 5HIAA (+32%, +20%) in the hypothalamus. These results indicate a clear interaction between substrate and coenzyme precursor which influences brain metabolism of histamine and serotonin.

Comparative effects of polymyxin B and compound 48/80 on histamine metabolism in rat muscle and gastric tissue

Polymyxin B, administered in vivo, increased histidine decarboxylase (HDC) activity and histamine (HM) concentrations in muscle tissue homogenates and supernatants. When administered in vitro it increased HDC activity and HM concentrations in both muscle and gastric tissue. The stimulatory effect on muscle was similar to that obtained with compound 48/80, but 48/80, unlike polymyxin B, did not affect gastric tissue. In vitro additions of alpha-fluoromethylhistidine inhibited both in vivo and in vitro stimulatory effects of polymyxin B. The results of these studies show that the action of compound 48/80 and of polymyxin B are similar, and that both affect HM synthesis in a manner that requires further elucidation.

Diamine oxidase in the hen

In adult hens diamine oxidase (histaminase) activity was found in gastrointestinal tract (with the highest value in ileum), liver and spleen. Intestinal diamine oxidase is predominantly a particle-bound enzyme. In the intestine oxidation of putrescine leads to delta 1-pyrroline formation, in liver both delta 1-pyrroline and gamma-aminobutyric acid are formed. The inhibitor properties of hen intestinal and rat intestinal diamine oxidases are very similar and differ from pea seedling diamine oxidase. The natural dipeptides carnosine and anserine are relatively potent inhibitors of hen intestinal diamine oxidase.

Influence of dietary histidine on tissue histamine concentration, histidine decarboxylase and histamine methyltransferase activity in the rat

Three-week-old male rats were fed for two weeks diets supplying inadequate, adequate, or excess amounts of histidine. After the 2-week feeding of the experimental diets, the rats were killed. Brain, gastrocnemius muscle, kidney and stomach were removed and analyzed for histamine and free-histidine as well as for the degradative enzyme, HMT, and the histamine-synthesizing enzyme HDC. The following results were obtained: As the levels of dietary histidine increased, (1) tissue concentrations of free-histidine and of histamine increased in all the tissues analyzed. (2) The increase of histamine was greatest in brain and stomach (5- and 4-fold, respectively), but less in kidney and muscle (2-fold). (3) HDC activity was not detected in muscle, but doubled from the lowest to the highest histidine intake in brain and increased almost 6-fold between the lowest and the highest histidine levels in stomach. (4) Kidney HDC decreased from the lowest to the two higher levels of dietary histidine. (5) HMT activity increased nominally in brain and not significantly in kidney; none was detected in either muscle or stomach. (6) Brain and kidney, tissues with considerable HMT activity, had almost no histamine. The increases in tissue histamine concentrations observed in the tissues analyzed generally reflected the changes and magnitudes of enzyme activities for HMT and HDC. The results in the rat differ in important ways from those previously observed in chickens as follows: (1) Histamine concentrations as a function in dietary histidine decreased in the chick. (2) Both HDC and HMT activities were present in chick muscle tissue. (3) HDC activity in chick stomach decreased sharply as a function of dietary histidine.