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Presented is an in vivo animal model of necrotizing enterocolitis (NEC) in which we used an isolated loop of rabbit colon. Changes in mucosal perfusion and macroscopic and microscopic appearances were studied after exposure of the mucosa to different intraluminal tensions and pHs. Mucosal perfusion was reduced with increasing intraluminal tension and decreasing pH. Histologic changes consistent with NEC were identified after five hours when the mucosa had been exposed to both increased intraluminal tension and decreased pH. Factors affecting intraluminal tension and pH could influence the development of NEC in the neonate.

In a previous study of the excretion of components in the urine of normal subjects, marked variations were observed in responce to daily foods and conditions in the body.The effect of dosed various acidee and bases on the excretion of urinary substances was investigated in this report.The administration of HCl, NH4Cl and NaCl increased total base and Cl after 3 hours in the urinary excretion, respectively, but that of NaHCO3 increased total base only.HCl, organic acids and sugared water decreased pH and produced increases in the excretion of NH3, H3PO4 and titratable acidity.

With a decreased pH of milk the fouling process became faster, especially below pH 5.6. Also the final relatively steady flux was appreciably lower with lower pH. It seemed that aggregation of casein with decreasing pH enhanced fouling of the membrane. Presence of fat caused faster fouling, however, the extent of fouling was not significantly influenced. Decrease in flux was appreciably faster with skimmilk than with whey.

We have investigated the responses of two closely related human colon tumour lines (clone A and clone D) to hyperthermic cell killing in vitro under two conditions of environmental acidity (pH values 7.40 and 6.75). At pH 7.40, under prolonged exposure to 42.5 degrees C, both lines exhibited biphasic response curves with thermotolerance appearing at about 4 h of continuous heating. It was found that the clone D human tumour line was more resistant to hyperthermic inactivation than the clone A line. At pH 6.75, both lines exhibited increased sensitivity to heating killing at 42.5 degrees C, but it was found that the effect was unequally demonstrated by the two human tumour lines (i.e. decreased pH was not acting simply as a dose modifying agent). Specifically, clone A exhibited a much greater hyperthermic sensitivity in the thermotolerant region of survival (i.e. a heating time of 4 h or more) than did clone D. Clinically, this result would suggest that although potential pH sensitization of heterogeneous tumours to hyperthermic cell killing may vary in a random manner among tumour cell subpopulations within a given tumour, the increased heat sensitivity found may produce isosurvival results for equal heating times for the different subpopulations.

Amniotomy is done frequently for the purpose of shortening labor or applying an internal fetal monitor electrode. To determine if amniotomy is warranted as a routine procedure, a systematic review of literature on the subject was done. Studies pertaining to the length of labor showed either no consistent effect of amniotomy, or a shorter labor by a maximum of 61.5 min with early amniotomy. Studies pertaining to the condition of the fetus showed increased incidence of caput succedaneum, skull bone disalignment, and early decelerations with early amniotomy. A small controlled study showed decreased pH of newborns with early amniotomy. There was no significant difference in Apgar score or neurological examination of the newborn with early amniotomy. The author concluded that early amniotomy should be reserved for use with specific indications, and should not be used routinely in the low-risk parturient.

The influence of pH and 3-hydroxybutyrate on insulin binding and action has been studied in cultured human fibroblasts. When the pH of the incubation medium was decreased from 7.6 to 6.8, insulin stimulation of glycogen synthase and total glucose uptake was decreased. The decreased pH induced both an increase in the insulin concentration for half-maximal response, and a decrease in maximal responsiveness. When insulin binding was measured at lower pH, receptor affinity was decreased. The effect of 3-hydroxybutyrate on insulin binding and action was assessed at pH 7.4 and 6.9. In the presence of 3-hydroxybutyrate, insulin binding increased, but insulin action on glycogen synthase and total glucose uptake was unaffected. The data show that insulin action is impaired at lower pH. The decreased sensitivity is probably related to the decrease in insulin binding affinity at lower pH, but decreased maximal responsiveness implies that postreceptor components are also affected by lower pH. The results also suggest that 3-hydroxybutyrate induced a dissociation between binding and response, since an increase of insulin binding was not accompanied by changes in the regulation of glycogen synthase and total glucose uptake.

Substantial variations are reported for egg production and hatching rates of copepods exposed to elevated carbon dioxide concentrations (pCO2). One possible explanation, as found in other marine taxa, is that prior parental exposure to elevated pCO2 (and/or decreased pH) affects reproductive performance. Previous studies have adopted two distinct approaches, either (1) expose male and female copepoda to the test pCO2/pH scenarios, or (2) solely expose egg-laying females to the tests. Although the former approach is more realistic, the majority of studies have used the latter approach. Here, we investigated the variation in egg production and hatching success of Acartia tonsa between these two experimental designs, across five different pCO2 concentrations (385–6000 µatm pCO2). In addition, to determine the effect of pCO2 on the hatching success with no prior parental exposure, eggs produced and fertilized under ambient conditions were also exposed to these pCO2 scenarios. Significant variations were found between experimental designs, with approach (1) resulting in higher impacts; here >20% difference was seen in hatching success between experiments at 1000 µatm pCO2 scenarios (2100 year scenario), and >85% at 6000 µatm pCO2. This study highlights the potential to misrepresent the reproductive response of a species to elevated pCO2 dependent on parental exposure.

In order to confirm that the flat sour spoilage of canned shiruko (a sweet bean drink) is the same as the new type of flat sour spoilage (O. A. flat sour spoilage) of canned coffee, investigations were carried out on commercial canned shiruko.Samples of canned shiruko were taken from a lot which had suffered from flat sour spoilage. The samples were incubated at 55°C and examined microbiologically. Six and thirty spoiled cans were found after 10 days and 30 days, the spoilage rates being 20% and 100%, respectively.The contents of the spoiled cans were reddish or yellowish, and had a slight smell of hydrogen sulfide and a slight bitterness. The spoiled cans of shiruko showed decreased pH values but not decreased vacuum levels. Though this is a difference from the spoilage of canned coffee, the 16 isolated strains have the same principal characteristics as the causative bacteria of O. A. flat sour spoilage of canned coffee.Therefore, sugar, which is the only common ingredient used in both canned shiruko and coffee, is likely to be the source of the causative bacteria.

GLIC is a pentameric proton-gated ion channel with an EC50 at pH of 5.0. It remains unclear which regions of GLIC are responsible for channel activation. In this study, we explore two potential regions by combining mutagenesis/functional experiments with computations using the Perturbation-based Markovian Transmission (PMT) model. The first region involves inter-subunit salt bridges between the C-loop (E177 and D178) and β5 (D91) of the complementary side. The second region (N152, D153, and D154) was part of the cavity identified crystallographically for anesthetic ketamine binding (Pan, Chen, et.al, Structure, 20, 1463, 2012). Mutations in the first region (D91N, E177Q, D178N) removed salt bridges and resulted in an increase of the EC50 (decreased pH to 4.8), suggesting the importance of the salt bridges in stabilizing the open-channel conformation, as confirmed by the less closed C-loop in the X-ray crystal structure. The mutation in the second region (N152C) resulted in a decreased of the EC50 (increased the pH to 5.4), presumably due to more flexibility for the protonation of D153 and D154. Using the PMT model, which provides time dependent information on the pathway of signal propagation, we found that perturbations to the first and second regions propagated through two different paths to the pore-lining TM2. The perturbation to the first region travels mainly from loop C, down β10 and β7 to the Cys-loop, and on to TM1 and TM3, which together affect TM2. The perturbation in the second region starts in the middle of the F-loop, travels down along the F-loop into the TM2-TM3 linker, and then to TM2. Taken together, our results reveal residues important to channel activation and allosteric signal pathways. Supported by NIH (R01GM066358, R01GM056257, R37GM049202, and T32GM075770).