Supplementation of pancreatic digestive enzymes alters the composition of intestinal microbiota in mice

Although pancreatic enzyme replacement therapy (PERT) is effective in the alleviation of pancreatic exocrine insufficiency (PEI)-related symptoms in patients with chronic pancreatitis, its mechanism of action is poorly understood. Recent studies suggest that the intestinal microbiota is associated with the pathogenesis of chronic pancreatitis. Therefore, we hypothesized that PERT exerts its effect by modifying the intestinal microbiota in addition to its presumed role in promoting fat and protein absorption. To explore the mechanism of action of PERT, we analyzed the intestinal microbiotas of two groups of mice treated with either pancrelipase or tap water by using 16S rRNA amplicon sequencing. The results revealed that the bacterial compositions of the pancrelipase-treated mice were significantly different from those of the control samples. Akkermansia muciniphila, a key beneficial bacterium in the intestinal tract, showed a higher relative abundance in the pancrelipase-treated samples than in the control samples. Lactobacillus reuteri, a widely used probiotic bacterium known to relieve intestinal inflammation, also showed a higher relative abundance in the pancrelipase-treated samples. These results suggested that PERT induces the colonization of beneficial bacteria, thereby contributing to the attenuation of PEI-associated symptoms in addition to improvement of the nutritional state.     

Chronic kidney disease after 5/6 nephrectomy disturbs the intestinal microbiota and alters intestinal motility

Organ–organ crosstalk is involved in homeostasis. Gastrointestinal symptoms are common in patients with renal failure. The aim of this study was to elucidate the relationship between gastrointestinal motility and gastrointestinal symptoms in chronic kidney disease. We performed studies in C57BL/6 mice with chronic kidney disease after 5/6 nephrectomy. Gastrointestinal motility was evaluated by assessing the ex vivo responses of ileum and distal colon strips to electrical field stimulation. Feces were collected from mice, and the composition of the gut microbiota was analyzed using 16S ribosomal RNA sequencing. Mice with chronic kidney disease after 5/6 nephrectomy showed a decreased amount of stool, and this constipation was correlated with a suppressed contraction response in ileum motility and decreased relaxation response in distal colon motility. Spermine, one of the uremic toxins, inhibited the contraction response in ileum motility, but four types of uremic toxins showed no effect on the relaxation response in distal colon motility. The 5/6 nephrectomy procedure disturbed the balance of the gut microbiota in the mice. The motility dysregulation and constipation were resolved by antibiotic treatments. The expression levels of interleukin 6, tumor necrosis factor-α, and iNOS in 5/6 nephrectomy mice were increased in the distal colon but not in the ileum. In addition, macrophage infiltration in 5/6 nephrectomy mice was increased in the distal colon but not in the ileum. We found that 5/6 nephrectomy altered gastrointestinal motility and caused constipation by changing the gut microbiota and causing colonic inflammation. These findings indicate that renal failure was remarkably associated with gastrointestinal dysregulation.     

Susceptibility dynamics in neonatal BALB/c mice infected with Cryptosporidium parvum.

BALB/c Mice were infected as neonates and at different ages to study the susceptibility dynamics in this animal model to Cryptosporidium parvum. When 4-day-old animals were infected with 10(5) C. parvum oocysts, parasites were detected in the terminal ileum when the mice became 14-25 days old (10-21 days post-infection [PI]). The percentage of animals positive for parasites was 100% up to the age of 19 days (15 days PI) but decreased immediately thereafter until no parasites were detected in 26-day-old (22 days PI) or older mice. Parasite load also decreased in these animals from 184.7 parasites per high power field in 14-day-old animals (10 days PI) to 0.22 in 25-day-old (21 days PI) mice. In a second study, some neonatal mice became resistant to C. parvum when infection was attempted at day-10 of age (day-15 of age at sacrifice). The susceptibility to C. parvum decreased until 14 days of age (19 days of age at sacrifice) when mice could no longer be infected. Parasite load also decreased in infected mice from 235.6 parasites per high power field (9 days of age at sacrifice) to 0.25 (18 days of age at sacrifice).     

High-fat diet alters gut microbiota physiology in mice

The intestinal microbiota is known to regulate host energy homeostasis and can be influenced by high-calorie diets. However, changes affecting the ecosystem at the functional level are still not well characterized. We measured shifts in cecal bacterial communities in mice fed a carbohydrate or high-fat (HF) diet for 12 weeks at the level of the following: (i) diversity and taxa distribution by high-throughput 16S ribosomal RNA gene sequencing; (ii) bulk and single-cell chemical composition by Fourier-transform infrared- (FT-IR) and Raman micro-spectroscopy and (iii) metaproteome and metabolome via high-resolution mass spectrometry. High-fat diet caused shifts in the diversity of dominant gut bacteria and altered the proportion of Ruminococcaceae (decrease) and Rikenellaceae (increase). FT-IR spectroscopy revealed that the impact of the diet on cecal chemical fingerprints is greater than the impact of microbiota composition. Diet-driven changes in biochemical fingerprints of members of the Bacteroidales and Lachnospiraceae were also observed at the level of single cells, indicating that there were distinct differences in cellular composition of dominant phylotypes under different diets. Metaproteome and metabolome analyses based on the occurrence of 1760 bacterial proteins and 86 annotated metabolites revealed distinct HF diet-specific profiles. Alteration of hormonal and anti-microbial networks, bile acid and bilirubin metabolism and shifts towards amino acid and simple sugars metabolism were observed. We conclude that a HF diet markedly affects the gut bacterial ecosystem at the functional level.     

Orally administered heat-killed Lactobacillus gasseri TMC0356 alters respiratory immune responses and intestinal microbiota of diet-induced obese mice

Aims: To investigate the influence of heat‐killed Lactobacillus gasseri TMC0356 on changes in respiratory immune function and intestinal microbiota in a diet‐induced obese mouse model. Methods and Results: Male C57BL/6J mice were fed a high‐fat diet for 16 weeks. After 8 weeks, the high‐fat‐diet‐induced obese mice (DIO mice) were randomly divided into two 0067roups, the DIO and DIO0356 groups. DIO0356 group mice were orally fed with heat‐killed TMC0356 every day for 8 weeks, while DIO group mice were exposed to 0·85% NaCl over the same time period as controls. After intervention, the pulmonary mRNA expression of cytokines and other immune molecules in DIO0356 mice compared to those in DIO group mice was significantly increased (P < 0·05, P < 0·01). In faecal bacterial profiles, analysed using the terminal restriction fragment length polymorphism (T‐RFLP) method, T‐RFLP patterns in 75% of the DIO0356 group mice were apparently changed compared with those in control group mice. Conclusion: These results suggest that inactive lactobacilli may stimulate the respiratory immune responses of obese host animals to enhance their natural defences against respiratory infection, partially associating with their potent impact on intestinal microbiota. Significance and Impact of the Study: We have demonstrated that oral administration of inactive lactobacilli may protect host animals from the lung immune dysfunction caused by obesity.     

铁皮石斛对脾虚便秘小鼠肠道菌群多样性的影响

探讨铁皮石斛对脾虚便秘小鼠肠道菌群的影响,为铁皮石斛对脾虚便秘的疗效机制及临床组方提供依据。

选取12只SPF级昆明小鼠随机分为正常组、模型组、铁皮石斛组和枳术汤组,每组3只。造模阶段正常组灌胃无菌水,模型组和治疗组采用番泻叶水煎液灌胃7 d后,限制饮食饮水8 d,建立脾虚便秘模型。造模成功后,正常组和模型组灌胃无菌水,治疗组分别以铁皮石斛和枳术汤水煎液干预5 d。治疗结束后,收集各组小鼠盲肠内容物样本进行16S rDNA高通量测序。

脾虚便秘小鼠排便量减少,粪便细小,干燥,质硬,呈黄色。铁皮石斛和枳术汤分别治疗后,小鼠排便量增加,粪便软硬适中,呈黑褐色。测序分析发现,正常组与铁皮石斛组的共有OTU数最多,与枳术汤组的共有OTU数最少。α−多样性指数与PCA结果表明,铁皮石斛组菌属结构较其余两组更接近正常组小鼠。物种相对丰度及组成结果表明,铁皮石斛增加了脾虚便秘小鼠双歧杆菌属相对丰度,抑制了乳杆菌属、拟杆菌属相对丰度,但对菌群丰度的调节作用不及枳术汤;LEfSe分析与随机森林分析鉴定出布劳特菌属和活泼瘤胃球菌是铁皮石斛组与其他组别的差异菌群。

铁皮石斛能恢复脾虚便秘小鼠肠道菌群的多样性,可调节肠道菌群相对丰度,布劳特菌属和活泼瘤胃球菌可能是铁皮石斛干预脾虚便秘小鼠的肠道关键指示菌。

     

蜂蜜对洛哌丁胺诱导的便秘小鼠肠道微生态的影响

目的 观察蜂蜜对洛哌丁胺诱导的便秘小鼠肠道微生态的影响。方法 雄性Balb/c小鼠30只,随机分成两组：正常对照组（10只）、模型组（20只）,同时模型组再分为自然恢复组（10只）、蜂蜜组（10只）。应用洛哌丁胺制备便秘小鼠模型,分别于造模后、给蜂蜜后第5天对每只小鼠进行称重、采便;之后于第12天称重、采便,处死小鼠,进行小肠推进率、结肠组织血管活性肠肽（VIP）、P物质（SP）、5-羟色胺（5-HT）测定和肠道菌群检测。结果 洛哌丁胺造模后的第5天,模型组小鼠粪便含水量及体质量下降;蜂蜜组小鼠体质量下降,但粪便含水量无明显变化。蜂蜜治疗至第12天时,蜂蜜组小鼠与模型组比SP增加,粪便含水量及小肠推进率增加,蜂蜜组小鼠与模型组比VIP、5-HT变化不明显。此外蜂蜜干预后便秘小鼠肠道中拟杆菌属和厚壁菌属的细菌丰度有所降低,Alistipes obesi的含量增加。结论 蜂蜜对小鼠5-HT分泌水平无明显影响;可以提高便秘小鼠结肠组织中SP含量、增加粪便含水量、加快小肠推进率;调节肠道微生态失衡,对便秘发挥一定的治疗作用。     

番泻叶造模对小鼠肠道微生物及酶活性的影响

目的 探讨灌胃番泻叶脾虚腹泻造模方法对小鼠肠道微生物及酶活性的影响。方法 采用灌胃番泻叶水煎液进行小鼠脾虚造模。12只小鼠随机分为模型组和正常组,模型组灌胃番泻叶水煎液,正常组灌胃等量无菌水,期间观察小鼠的一般情况变化。灌胃7 d后称重、无菌采集肠道内容物,分析肠道菌群及酶活性。结果 与正常组相比,模型组小鼠肠道内容物的淀粉酶活性升高极显著（t=-53.0671,P=0.0000）,纤维素酶活性和木聚糖酶活性下降显著（t=23.1230,P=0.0000;t=12.3900,P=0.0410）,而蛋白酶活性变化不明显（t=1.3120,P=0.0521）;模型组小鼠细菌总数显著减少（t=73.1601,P=0.0000）,而大肠埃希菌、乳杆菌、双歧杆菌和真菌总数变化均不明显（t=2.3580,P=0.1432;t=2.2089,P=0.1127;t=2.2813,P=0.1037;t=9.3210,P=0.0510）。结论 脾虚造模会使细菌总数减少,纤维素酶和木聚糖酶活性下降,淀粉酶活性升高。     

葛根芩连汤对肠道湿热证泄泻小鼠肠道微生物的影响

目的探讨葛根芩连汤对肠道湿热证泄泻小鼠肠道微生物的影响。方法造模:10只KM雄性小鼠随机分为正常组5只和模型组5只,采用"高糖高脂+高温高湿+白酒复合灌胃冰水"的方法制备肠道湿热证泄泻小鼠模型。治疗:15只KM雄性小鼠随机分为正常组5只和模型组10只,造模成功后将模型组小鼠分为自愈组和治疗组,治疗组小鼠运用葛根芩连汤进行治疗,分别在造模和治疗后无菌采集小鼠肠道内容物进行微生物培养。结果造模后,小鼠出现懒动、肛温升高、体重增长缓慢、黄褐色稀便、肛门污秽等湿热泄泻症状,肠道乳杆菌数高于正常组,而细菌总数、肠杆菌、双歧杆菌、B/E值降低,其中细菌总数以及双歧杆菌数与正常组相比差异有统计学意义(t=14.182,P0.001;t=2.797,P=0.049)。经葛根芩连汤治疗后,小鼠肠道乳杆菌和双歧杆菌数高于正常组,而细菌总数、肠杆菌数低于正常组,且乳杆菌数和肠杆菌数与正常组相比差异有统计学意义(t=-5.210,P=0.033;t=-11.160,P=0.008),B/E值与正常组差异无统计学意义(t=-1.427,P=0.227)。结论造模使小鼠肠道双歧杆菌数显著降低,B/E值下降;葛根芩连汤可促进肠道湿热证泄泻小鼠肠道乳杆菌和双歧杆菌的增生,提高B/E值。     

痛泻要方对肝气乘脾泄泻小鼠肠道微生物的影响

目的 探讨痛泻要方对肝气乘脾泄泻小鼠肠道微生物的影响,为肝气乘脾泄泻及中医经典药方治疗泄泻的机制提供实验依据。 方法 SPF级昆明小鼠随机分为正常组10只和模型组15只,造模成功后,取正常组和模型组各5只,将剩余模型组小鼠随机分为自然恢复组和痛泻要方干预组各5只,痛泻要方干预组灌胃痛泻要方治疗3 d,分别在造模成功和治疗后取肠道内容物进行微生物培养,然后记录内容物中各种菌的数量。 结果 造模后,模型组小鼠细菌总数、大肠埃希菌、双歧杆菌、乳杆菌的数量均有上升趋势,与正常组相比只有细菌总数[(23.9±3.51)vs(1.35±0.30),108 CFU/g]差异有统计学意义(t=-11.061,P=0.008)。治疗后,痛泻要方干预组小鼠恢复了肝气乘脾泄泻引起的肠道微生物失衡,其中与自然恢复组相比痛泻要方治疗对大肠埃希菌的影响最明显[(1.63±1.19)vs(8.47±0.84),106 CFU/g;t=8.124,P=0.001],细菌总数、双歧杆菌、乳杆菌数量均受影响,但差异无统计学意义(P>0.05)。肝气乘脾造模组小鼠的肠道微生物定植抗力(B/E值)降低,而痛泻要方干预组的趋近于正常组。 结论 肝气乘脾泄泻小鼠肠道细菌总数、大肠埃希菌、双歧杆菌、乳杆菌等的数量增加,B/E值降低,痛泻要方干预能够恢复肝气乘脾泄泻引起的肠道微生物失衡,并通过调节肠道微生物以提高B/E值来治疗泄泻。     

口服肝素与小鼠肠道菌群的相互作用

口服肝素药物的开发需要系统地理解口服肝素与肠道菌群之间的互作过程。通过荧光体视镜观察荧光素标记的肝素经小鼠口服后在体内的分布情况,利用高效液相色谱法检测肝素在模拟胃肠液中的稳定性和体外培养肠道菌群模拟肠道菌对肝素的降解作用,发现口服肝素主要分布在小鼠胃肠道内,在体外模拟胃肠液条件下肝素结构稳定,但能够被添加肝素的厌氧培养基培养后的肠道菌群降解。为了进一步揭示口服肝素对健康小鼠肠道菌群的影响,利用Illumina MiSeq高通量测序技术测定口服肝素后C57BL/6J小鼠粪便菌群的16S rRNA序列,与口服生理盐水的小鼠粪便菌群进行对比,发现口服肝素的小鼠粪便菌群的生物多样性降低;在门水平上,菌群结构差异不显著;而在属水平上,别样杆菌属Alistipes、副萨特氏菌属Parasutterella和艾克曼菌属Akkermansia相对丰度增高,而嗜胆菌属Bilophila、肠杆菌属Enterorhabdus、瘤胃梭菌属Ruminiclostridium、普雷沃氏菌科Prevotellaceae_UCG_001、瘤胃梭菌属Ruminiclostridium-9、拟杆菌属Bacteroides、Lachnoclostridium、Candidatus_Saccharimonas、Intestinimonas和Dubosiella的相对丰度减少,表明口服肝素能够影响小鼠肠道菌群结构。此外,实验发现口服肝素对小鼠无明显毒副作用,具有较高安全性。研究结果将为开发肝素口服递送策略提供新的思路,为口服肝素类药物的开发提供参考。     

Osteosarcomas in BALB/c female mice

Osteosarcomas were found in 16 of 24,192 (0.066%) BALB/c female mice, 14 were in 21,816 (0.064%) 2-acetylaminofluorene-treated mice, and two were in 2,376 (0.084%) untreated controls. The osteosarcomas were classified into osteoblastic, fibroblastic, and mixed types. Seven of the osteosarcomas metastasized to the lungs. The osteosarcomas in control and 2-acetylaminofluorene-treated mice showed little or no difference in the incidence, type, size, or site of origin, indicating that 2-acetylaminofluorene did not affect the development of osteosarcomas in BALB/c female mice.U     

四磨汤口服液对脾虚便秘小鼠肠道微生物及酶活性的影响

目的探讨四磨汤对脾虚便秘疗效、肠道微生物和酶活性的影响。方法将18只实验小鼠随机分成模型组、正常对照组和治疗组,每组6只。对模型组和治疗组采用灌胃番泻叶水煎液7 d后控制饮食,饥饱失常8 d,进行小鼠脾虚便秘造模。造模结束后,模型组和正常对照组均用无菌水灌胃,治疗组用四磨汤口服液灌胃,共7 d,然后采集肠道内容物,分析肠道菌群及酶活性。结果模型组自然恢复后,肠道微生物(细菌总数、大肠埃希菌、乳酸菌、双歧杆菌和真菌)、纤维素酶活性、木聚糖酶活性、淀粉酶活性和蛋白酶活性与正常对照组比较差异有统计学意义(P0.01或P0.05)。治疗组大肠埃希菌数和真菌数与正常对照组比较差异无统计学意义(P0.05),达到正常对照组水平。细菌总数显著增加(P0.01),乳酸菌显著减少(P0.05),双歧杆菌数目显著增加(P0.01),治疗组纤维素酶和木聚糖酶活性极显著低于正常对照组(P0.01),淀粉酶活性极显著高于正常对照组(P0.01),蛋白酶活性与正常对照组比较差异无统计学意义(P0.05)。结论四磨汤通过调控肠道菌群平衡,调整肠道酶活性来治疗脾虚便秘。     

加味甘麦大枣汤对气血两虚型产后抑郁症患者肠道菌群和血清5-HT的影响

观察加味甘麦大枣汤对气血两虚型产后抑郁症（PPD）患者肠道菌群和血清5-羟色胺（5-HT）水平的影响。

选取2022年10月至2023年8月就诊于甘州区妇幼保健院且符合纳入标准的气血亏虚型产后抑郁症患者60例作为研究对象,按其就诊顺序随机分为观察组、对照组,每组各30例。对照组给予西医常规治疗,观察组在西医常规治疗基础上联合加味甘麦大枣汤治疗,疗程4周。分别于治疗前和治疗后采用中医证候积分和汉密尔顿抑郁量表（HAMD）评价治疗疗效。通过高通量测序法检测两组患者治疗前后粪便中的菌群多样性和各分类学水平分布。采用酶联免疫吸附测定（ELISA）检测两组患者血清5-HT水平。

与本组治疗前比较,治疗后两组患者中医证候积分和HAMD评分均明显下降,差异具有统计学意义（P＜0.05）。治疗后,与对照组比较,观察组的中医证候积分和HAMD评分显著下降（P＜0.05）。观察组临床有效率为96.7%,高于对照组的76.7%（χ²=8.967,P=0.030）。观察组肠道菌群在治疗后的Simpson指数和Shannon指数较治疗前升高（P＜0.05）,拟杆菌门（Bacteroidetes）、瘤胃菌科（Ruminococcaceae）、拟杆菌属（Bacteroides）和双歧杆菌属（Bifidobacterium）相对丰度显著高于对照组（P＜0.05）,变形菌门（Proteobacteria）、肠杆菌科（Enterobacteriaceae）、粪球菌属（Coprococcus）和志贺菌属（Shigella）相对丰度显著低于对照组（P＜0.05）。两组患者血清5-HT水平治疗后均明显升高（P＜0.05）,观察组5-HT水平升高的更明显（P=0.010）。

加味甘麦大枣汤可辅助临床治疗改善PPD患者的临床症状,调节患者肠道菌群,提高血清5-HT水平。

     

Denaturing gradient gel electrophoresis of neonatal intestinal microbiota in relation to the development of asthma

Background  

The extended 'hygiene hypothesis' suggests that the initial composition of the infant gut microbiota is a key determinant in the development of atopic disease. Several studies have demonstrated that the microbiota of allergic and non-allergic infants are different even before the development of symptoms, with a critical time window during the first 6 months of life. The aim of the study was to investigate the association between early intestinal colonisation and the development of asthma in the first 3 years of life using DGGE (denaturing gradient gel electrophoresis).     

咖啡摄入量对小鼠肠道微生物及酶活性的影响

目的 研究摄入不同咖啡浓度对小鼠酶活性、肠道微生物、体重的影响,从分析肠道四种微生物变化和四种酶的活性变化来讨论摄入咖啡对健康的影响。方法 SPF级昆明小鼠随机分为4组,即低、中、高咖啡浓度组和正常对照组,所有实验组小鼠日常给予蒸馏水饮用,实验低、中、高浓度组每天2次分别灌胃给予0.0045 g/mL、0.0090 g/mL、0.0180 g/mL的咖啡溶液0.4 mL/（只•次）,对照组给予蒸馏水灌胃,实验时间为1个月,测小鼠体重、肠道微生物和酶活性等指标并进行分析。结果 与对照组相比,低浓度咖啡摄入组乳杆菌、双歧杆菌、大肠埃希菌数显著增加（P＜0.01或P＜0.05）,需氧和厌氧细菌数显著降低（P＜0.01）;中浓度咖啡摄入组乳杆菌、双歧杆菌数显著低于对照组和低浓度组（P＜0.01）,大肠埃希菌显著高于对照组（P＜0.05）;高浓度咖啡摄入组乳杆菌和大肠埃希菌总数显著低于对照组（P＜0.01或P＜0.05）;低浓度摄入组的木聚糖酶、纤维素酶、淀粉酶、蛋白酶的活性均显著高于（Ps＜0.01）对照组和中浓度咖啡摄入组;各组小鼠体重差异无统计学意义（P＞0.05）。结论 适当摄入咖啡小鼠肠道双歧杆菌和乳杆菌等益生菌数量增加显著,小鼠肠道中具有代表性的淀粉酶、纤维素酶、蛋白酶、木聚糖酶的活性均显著增加,但咖啡摄入对小鼠体重影响不显著。     

西芹提取液对高脂小鼠肠道菌群平衡的影响

目的应用PCR-DGGE技术评价西芹对昆明小鼠肠道菌群平衡的影响。方法给予小鼠高脂饲料,复制高脂模型,模型复制成功后,每日给予小鼠西芹提取液灌胃,连续28 d。分别在实验的0、14和42 d,收集每只小鼠粪便,提取基因组DNA,应用PCR-DGGE(聚合酶链式反应——变性梯度凝胶电泳)技术获得肠道菌群分子指纹图谱,针对相似性、多样性分析及优势条带的序列进行分析。结果高脂饲料喂养后肠道益生菌约氏乳杆菌等趋近消失,出现了特异菌真杆菌,而西芹灌胃组和食用基础饲料组真杆菌数量显著减少,且西芹灌胃组作用大于食用基础饲料自然恢复组。结论西芹对高脂小鼠肠道菌群的平衡有显著的恢复作用。     

Infant formula ingestion is associated with the development of diabetes in the BB/Wor rat

The association between early exposure to cow's milk products in infancy and risk for insulin dependent diabetes mellitus (IDDM) is controversial. We examined whether the ingestion of cow's milk-based infant formula altered the expression of the diabetic syndrome in the BB/Wor rat, an animal model of IDDM. Pregnant BB/Wor dams were obtained from the NIH contract colony at the University of Massachusetts and housed under semi-barrier conditions. Rat pups were intubated with 1 to 2 ml of commercially available cow's milk-based infant formula (Enfamil or Nutramigen) or sham intubated (controls) daily from day 12 to day 25 of life. Pups were weaned at day 25 and monitored for glucosuria daily through 120 days of life. All rats including dams consumed a milk-free rat chow and acidified water ad libitum throughout the study. The mean age of disease onset was 4 to 10 days earlier in Nutramigen-fed and Enfamil-fed rats relative to controls (84+/-3, 78+/-2 and 88+/-4 days, respectively); the mean age of disease onset was significantly different between controls and Enfamil-fed animals (p<0.05). At 120 days, 60% (12/20) of control rats developed diabetes versus 100% of animals fed either type of infant formula prior to weaning (15/15:Enfamil-fed; 19/19:Nutramigen-fed) (p<0.05). These data indicate that direct, early ingestion of cow's milk-based formula was related to the expression of diabetes in the BB/Wor rat.     

The frequency of para-azophenylarsonate and dimethylaminonapthalene-sulfonyl-specific B cells in neonatal and adult BALB/c mice.

The limiting cell dilution splenic focus technique has been used to determine the frequency of p-azophenylarsonate (Ars) and 5-dimethylaminonaphthalene-sulfonyl (Dansyl)-specific B cells in neonatal and adult mice. The adult frequencies for Ars and Dansyl in conventionally reared BALB/c mice are 1.5 +/- 0.3/10(5) B cells and 9.4 +/- 3.3/10(5) Bcells, respectively. Dansyl-specific precursor cells are present in high frequencies at birth and reach adult precursor frequency levels during the first week of life. This finding mirrors the ontogenetic development previously described fro dinitrophenyl (DNP) and trinitrophenyl (TNP), but contrasts with the results obtained fro fluorescein (FL) and phosphorylcholine (PC), for which precursors arise later in development. On the other hand, the kinetics of appearance of B cells specific for Ars is unique in that the precursor frequency appears to decrease during the first week of life. The data presented remain consistent with a highly ordered, rigorously predetermined acquisition of the specificity repertoire during ontogeny. By increasing the flexibility of the splenic focus technique to allow analysis of other, chemically diverse haptens, results have been obtained that confirm and extend observations made with DNP, TNP, FL, and PC.