Mechanism and timing of nasopharyngeal closure during swallowing and belching

The mechanism(s) of nasopharyngeal closure (NPC) and its temporal relationship with other biomechanical events during swallowing and belching were studied in seven healthy volunteers, aged 26-39 yr, by concurrent videoendoscopic, videofluoroscopic, and manometric technique. Analysis of the videoendoscopic recordings showed that deglutitive NPC consisted of elevation of the soft palate and adduction of the superior pharyngeal constrictor muscle. Videofluoroscopy identified only the palatal elevation clearly. During belching, however, only palatal elevation occurred. Deglutitive NPC ranged between 0.73 and 0.94 s (0.8 +/- 0.04 SE), with a tendency to be longer with larger swallowed volumes. Onset of NPC was identified earlier endoscopically than as seen fluoroscopically. Complete NPC preceded the arrival of barium bolus into the pharynx, and this pattern was seen for all volumes tested. Manometric onset of upper esophageal sphincter (UES) relaxation was seen before the onset of NPC, but the physical opening of the UES as seen fluoroscopically occurred after complete closure of the nasopharynx. We conclude the following: 1) The mechanism of NPC during swallowing and belching is different. During swallowing, NPC has two tiers of closure, palatal elevation and superior pharyngeal muscle adduction; during belching only palatal elevation occurs. 2) NPC is tightly coordinated with other biomechanical events during swallowing and belching.

Manometric and Electrode-Probe Determination of CO2 in Fish Flesh

A rapid electrometric method for determining endogenous and added CO2 in fish products was studied using an Orion CO2 probe and Orion ionalyzer model #801. Analytical results were compared to those using the standard Warburg manometric technique. Comparisons showed a ± 20.8% mean difference for low concentrations of CO2 (<350 ppm) and a ± 10.7% mean difference for high concentrations of CO2 (>800 ppm). The probe technique was found to be easier to use and required less time for operating and cleanup procedures than the manometric method. Based on recovery studies, the specific ion probe was more accurate at all levels of CO2 evaluated than the manometric device.

Production of Tyrosine and Histidine Decarboxylase by Dairy-Related Bacteria

Manometric and radiometric procedures were used to determine the ability of 38 dairy-related bacteria and four commercial starter preparations to produce tyrosine and histidine decarboxylase. All of the cultures had slight ability to cause release of 14CO2 from carboxyl 14C-tyrosine and most released 14CO2 from labeled histidine; however, because of inherent errors of the assay in detecting low levels of specific decarboxylase activity, the CO2 release was not considered positive for specific decarboxylase activity unless the results were verified by the manometric technique. One strain of Streptococcus lactis, a Micrococcus luteus strain, and two Leuconostoc cremoris strains had active tyrosine decarboxylase systems. Only Clostridium perfringens and an Escherichia coli strain were found to produce histidine decarboxylase. None of the commercial starter cultures produced the enzymes. It was not determined whether tyramine or histamine was produced by the nonspecific decarboxylase activity.

EFFECT OF PHOSPHORUS AND SULPHUR FERTILIZATION ON THE NUTRITIVE VALUE OF SUBTERRANEAN CLOVER (TRIFOLIUM SUBTERRANEUM)

Phosphorus or sulphur applied alone to a soil deficient in P and S did not increase subterranean clover (Trifolium subterraneum) yields; but when the two elements were applied together, a five-fold ,increase was obtained. The nutritive value of the clover was evaluated by measuring sheep rumen microbial activity using an anaerobic manometric technique. Subterranean clover fertilized with P alone increased the microbial activity about 6%. In contrast, the clover fertilized with S alone decreased activity about 5%. When P and S were applied together, microbial activity was increased 20 to 30%, depending on the rates applied. There was a positive correlation between the level of reducing sugars in the clover and the degree of rumen microbial activity.