Koumiss Consumption Alleviates Symptoms of Patients with Chronic Atrophic Gastritis:A Possible Link to Modulation of Gut Microbiota

Intestinal dysbiosis is closely related to a variety of medical conditions,especially gastrointestinal diseases.The present study aimed to investigate the effects of koumiss on chronic atrophic gastritis(CAG)in an outpatient clinical trial(n=10;all female subjects aged 41-55;body mass index ranging from 19.5 to 25.8).Each patient consumed three servings of koumiss per day(i.e.250 ml daily before each of 3 meals)for a 60-day period.The improvement of patients'symptoms was monitored by comparing the total scores of symptoms before and after the treatment.Meanwhile,the changes in the patients’fecal microbiota composition and specific blood parameters were determined.After the 60-day koumiss administration,significant symptom improvements were observed,as evidenced by the reduction of the total symptoms score,and changes in blood platelet and cholesterol levels.The changes in patients’fecal microbiota composition were found.The patients’fecal microbiota fell into two distinct enterotypes,Bacteroides dorei/Bacteroides uniformis(BB-enterotype)and Prevotella copri(P-enterotype).Significant less Bacteroides uniformis was found in the BB-enterotype patient group,while significant more butyrate-producing bacteria(e.g.Eubacterium rectale and Faecalibacterium prausnitzii)were found in the P-enterotype patient group,following koumiss administration.After stopping koumiss consumption,the relative abundance of some biomarker taxa returned to the original level,suggesting that the gut microbiota modulatory effect was not permanent and that continuous koumiss administration was required to maintain the therapeutic effect.In conclusion,koumiss consumption could alleviate the symptoms of CAG patients.Our results may help understand the mechanism of koumiss in alleviating CAG disease symptoms,facilitating the development of such products with desired therapeutic functions.

Maximizing the Minimum and Maximum Forcing Numbers of Perfect Matchings of Graphs

Let G be a simple graph with 2n vertices and a perfect matching.The forcing number f(G,M) of a perfect matching M of G is the smallest cardinality of a subset of M that is contained in no other perfect matching of G.Among all perfect matchings M of G,the minimum and maximum values of f(G,M) are called the minimum and maximum forcing numbers of G,denoted by f(G) and F(G),respectively.Then f(G)≤F(G) ≤n-1.Che and Chen(2011) proposed an open problem:how to characterize the graphs G with f(G)=n-1.Later they showed that for a bipartite graph G,f(G)=n-1 if and only if G is complete bipartite graph K_(n,n).In this paper,we completely solve the problem of Che and Chen,and show that f(G)=n-1 if and only if G is a complete multipartite graph or a graph obtained from complete bipartite graph K_(n,n) by adding arbitrary edges in one partite set.For all graphs G with F(G)=n-1,we prove that the forcing spectrum of each such graph G forms an integer interval by matching 2-switches and the minimum forcing numbers of all such graphs G form an integer interval from [n/2] to n-1.