24-H pharyngeal pH monitoring in healthy volunteers: a normative study.

BACKGROUND: Gastropharyngeal reflux has been associated with disorders of the upper and lower airways. It may be shown by pharyngeal pH-metry, but reports on normality in healthy volunteers are scarce. No definite consensus has been reached considering the upper limit of normality (ULN). The aim of the present study was therefore to quantify the occurrence of pharyngeal acid exposure (pH < 4) in healthy volunteers and, further, to examine its relation to acid exposure of the oesophagus and oesophageal motility and its occurrence in relation to age, sex, and body position. METHODS: Forty healthy volunteers underwent ambulatory 24-h pH-metry, using antimony electrodes positioned 2 cm above the upper oesophageal sphincter and 5 cm above the lower oesophageal sphincter on the basis of manometry. Technical artefacts were excluded before calculation of all results. RESULTS: Gastropharyngeal reflux occurred in most healthy volunteers without any significant relation to age, sex, or body weight. Pharyngeal acid reflux occurred mainly in the upright position. The ULN for pharyngeal acid exposure time was assessed to 0.9% (0.2% after exclusion of mealtimes). The ULN for the number of acid events in the pharynx was 18 (6.1). The corresponding ULNs for the oesophagus were 7% and 84. CONCLUSION: Gastropharyngeal reflux may be effectively monitored by ambulatory pH-metry. The present study provides reference limits, a prerequisite for evaluating the pathophysiologic importance of the phenomenon.

Thermal oral-pharyngeal stimulation and elicitation of swallowing.

The influence of thermal stimulation of the oral and pharyngeal mucosa on the elicitation of swallowing was studied in 14 healthy volunteers. The Repeated Dry Swallowing Test was used to study the ability to elicit swallows. The test consists of 11 manometrically recorded dry swallows performed at maximum speed. The time between swallows 1 and 11 (Swallowing Test Time) is considered a measure of the ease of eliciting the swallowing reflex. The study includes two controlled experiments, each consisting of an active test done immediately after a cold stimulus and a control done after a stimulus at body temperature. In one experiment the stimulus consisted of stimulation of the fauces with a laryngeal mirror and in the other of swallowing water. Each subject served as his or her own control. The order of the tests was randomized and the results read blindly. In the mirror experiment, the swallowing test times obtained after application of a cold laryngeal mirror did not differ significantly from those obtained after stimulation at body temperature. In the water experiment, swallowing test times were shorter after swallowing cold water compared to those after swallowing water at body temperature in 11 of the 14 volunteers (n.s.). The concept that swallowing is significantly facilitated by cold applied to the oral-pharyngeal mucosa was thus not supported by the present study. The importance of these findings is discussed.

Neurotoxic effect on two fish species and a PC12 cell line of the supernate of Vibrio alginolyticus and Vibrio anguillarum.

The biological effects of supernates obtained from different strains of Vibrio alginolyticus and Vibrio anguillarum isolated from diseased fish have been studied by inoculation on two fish species, eel and rainbow trout, and two fish cell lines. These supernates possess neuroexcitatory properties, and so, when they are injected into both fish species, they trigger convulsions, wriggling, contortive swimming and respiratory arrest coupled with increased respiratory reflex. Furthermore, after the application of the supernates on cultures of noradrenergic pheochromocytoma PC12 cells, an increase of acetylcholine, released from the cells was obtained. The amount of released acetylcholine depends on the source of assayed supernates and on the dose applied to the cells. On the basis of the results obtained with PC12 cells, we suggest that the supernates from pathogenic Vibrio strains injected into fish may elicit an increased release of acetylcholine in the motor endplate of some muscles related to locomotion and ventilation of the inoculated fish.

Detection of aerolysin gene in Aeromonas strains isolated from drinking water, fish and foods by the polymerase chain reaction.

A polymerase chain reaction (PCR) technique was used to assay the presence of the aerolysin gene in a total of 89 Aeromonas hydrophila and A. sobria strains isolated from drinking water, fish and foods. These strains were also characterized for the production of virulence factors such as haemolysin, protease and cytotoxin. The primers used in the PCR targeted a 209-bp fragment of the aer gene coding for the beta-haemolysin and detected template DNA only in haemolytic A. hydrophila strains. The cell-free culture supernatants of these aerolysin-positive A. hydrophila strains were also cytotoxic to the HeLa and McCoy cells. The haemolytic A. sobria and non-haemolytic A. hydrophila were consistently negative in the PCR assay. Primer specificity was determined in the PCR by using a control haemolytic Escherichia coli, Streptococcus pyogenes and a restriction endonuclease assay. The PCR clearly identified the aerolysin-producing strains of A. hydrophila and may have application as a rapid species-specific virulence test.

Detection of potential virulence markers of Vibrio vulnificus strains isolated from fish in Sweden.

A variety of potential virulence markers such as the production of cytotoxin, haemolysin, exoenzymes, bactericidal action of sera, presence of capsule and adhesion to human intestinal cells were investigated on Vibrio vulnificus strains isolated from eels in Sweden. The strains had the capacity of producing all or some of the above-mentioned virulence markers, to varying degrees though none of the strains produced any capsule. The strains also bound specifically to human intestinal cells in vitro with maximum adhesion levels of 30 bacteria/cell. The results on binding of V. vulnificus cytotoxin to HeLa cells, showed that a very short exposure time (30 min) was required for inducing the cytotoxic effects. V. vulnificus is a relatively new addition to the list of bacteria pathogenic for humans, and since there are increasing reports on its isolation from aquatic environments and seafood (e.g. raw oysters, crabs and shellfish), the results on virulence profiles of V. vulnificus strains presented above emphasize the importance of these organisms in public health and epidemiological studies.

Scintigraphic detection of gastro-pulmonary aspiration in patients with respiratory disorders.

The scintigraphic detection of small nocturnal aspirations of radio-labelled gastric contents is difficult in the presence of high remaining activity in the abdomen, causing a non-uniform background activity. This problem was examined in phantom experiments and a technique for interpolative background correction was further developed. The accuracy of this technique was found to be influenced by the distance between the lung and the abdominal source of activity, and the minimum detectable 'aspirated' activity was determined as 0.1 MBq at a distance of 15 cm and 1 MBq at 5 cm. The interpolative technique for background correction was evaluated on healthy volunteers and laryngectomized patients, examined 10 h after intragastric instillation of 200 MBq of 99Tcm-pertechnetate. After background subtraction, their calculated pulmonary mean net count value was comparable to that registered before the radioactive tracer was administered. No localized accumulation of activity was found in any of these controls. The technique was then applied clinically to 55 patients with chronic respiratory disorders and symptoms of gastroesophageal reflux. Aspiration was detected in 11 patients (20%). Five aspirators had asthma, two a chronic cough of unknown origin, two recurrent pulmonary infections, and one chronic bronchitis and chronic laryngitis respectively. Aspiration was detected among patients with and without demonstrated pathological gastroesophageal reflux.

Quantitative assessment of esophageal transport with normalized condensed images.

Scintigraphy is one of several diagnostic procedures used to investigate dysphagia. Several different methods to present the bolus transport have been presented. The normalized condensed image enables quantitative assessments of patterns of bolus transport and a descriptive nomenclature of these patterns: the "L-h-S-E-m-system", based on results of 25 subjects without dysphagia, is suggested. Aberrant patterns were found in 40% of the swallows.

Fibronectin binding by Salmonella strains: evaluation of a particle agglutination assay.

Thirty-five Salmonella strains isolated from human cases of salmonellosis were tested and compared for their fibronectin (fn) binding capacities by using two fn-particle agglutination assays (fn-PAAs) prepared by coating with human fn either (i) latex beads (Difco; 0.81-micron diameter) (L-fn-PAA) or (ii) heat-killed formalin-treated Staphylococcus aureus Cowan 1 cells (C-fn-PAA). Six S. aureus strains were also included in this study as controls. The strains were cultured on colonization factor antigen agar and blood agar and in tryptic soy broth and brain heart infusion broth. The Salmonella and S. aureus strains were cultured at 33 and 37 degrees C, respectively, for optimal expression of fn-binding proteins. Bacterial cells (approximately 10(10) cells per ml) harvested from growth in various culture media and suspended in 0.02 M potassium phosphate buffer (pH 6.8) agglutinated the fn-PAA reagents. These reactions were scored semiquantitatively from + to + depending on the speed or intensity of the reactions within 2 min. Maximum agglutination in fn-PAA systems was observed when the cells were grown in brain heart infusion broth, while tryptic soy broth proved to be least suitable media for culturing cells for fn-PAAS. Although a statistically highly significant correlation was obtained between results of assays of radiolabeled fn and 29-kDa fragment binding, no significant correlation was observed (i) between the results of strains cultured in different media or (ii) when semiquantitative score results of the two fn-PAA systems were compared with those of the conventional radiolabeled fn assay. To enhance the efficiency of the test system, the C-fn-PAA reagent was stained with methylene blue (2% in 0.17 M glycine-NaOH buffer [pH 6.8]). This facilitated easy interpretation of results, which could be performed on hydrophobic paper instead of glass slides. The results obtained with both unstained C-fn-PAA and stained C-fn-PAA were comparable to each other and reproducible. Although the fn-PAAs are simple and easy to perform, the results did not differentiate between negative, low, moderate, and high binding abilities when Salmonella strains were evaluated for fn binding, and the results were not comparable to those obtained by the conventional radiolabeling method.

Growth of and toxin production by Aeromonas hydrophila and Aeromonas sobria at low temperatures.

The effects of different temperatures on the growth and toxin production of Aeromonas hydrophila and Aeromonas sobria were studied. The results showed that these Aeromonas species are not only able to grow at low temperatures (e.g. at 4 and 10 degrees C) but may also produce cytotoxin, hemolysin and enterotoxin under suitable growth conditions.

Infection of rabbit mammary glands with ovine mastitis bacterial strains.

An experimental model was developed in rabbits to study ovine mastitis. A total of 19 ovine mastitis bacterial strains (seven Staphylococcus aureus, four Staph. chromogenes, four Staph. hyicus and four Escherichia coli) were used for mammary gland infections. The histopathological results showed that the ovine mastitis types corresponded to experimental infections produced in the rabbit with the ovine strains. These results helped the grading of the bacterial species tested according to the severity of their effects on the mammary gland. The most pathogenic species was Staph. aureus, followed by E. coli, Staph. hyicus and Staph. chromogenes, in that order. There was, however, variation among strains within a given species (e.g. one out of seven Staph. aureus strains gave rise to a mild infection in sheep and rabbits). The procedure was simple and consisted of introducing bacterial suspensions through alternate teat ducts of does with the help of a cannula. It helped minimize the number of animals required in the experiments.

The prevalence of symptoms suggestive of esophageal disorders.

A questionnaire study was conducted to assess the prevalence and severity of symptoms suggestive of esophageal disorders in a general population. The study included 407 randomly selected subjects, evenly distributed in terms of sex and age, within the age span of 20-79 years. A total of 337 subjects replied (85%). Symptoms suggestive of gastroesophageal reflux were found among 25% of the participants. Cough on swallowing was common (27%), as was globus (16%) and chest pain (13%). In addition, dysphagia was reported by 10% and vomiting by 9%. The symptoms were usually mild, and moderate to severe symptoms were reported only occasionally (1-4%). No statistical correlation was found between esophageal symptoms and age, sex, or the reported consumption of tobacco, alcohol, or non-steroidal anti-inflammatory drugs. The frequency of heartburn and/or acid regurgitation was twice as common among those with symptoms of respiratory disease as among those with no respiratory complaints. A stepwise logistic regression analysis showed that a chronic cough and/or breathing difficulties were significantly related to the presence of symptoms suggestive of gastroesophageal reflux.

Enterotoxigenicity and drug sensitivity of Aeromonas hydrophila isolated from well water in Sweden: a case study.

A large number of Aeromonas spp. have been found in drinking water from a drilled well in Sweden. Isolates identified as A. hydrophila were tested for production of enterotoxin, hemolysin, enzymes and for resistant patterns to different antibiotics. The enterotoxin-producing A. hydrophila could be responsible for the long-term diarrhoeal case of a 1 1/2 year old child who consumed the contaminated water.

Delivery circumstances in relation to adult septum deviation.

The present study elucidates whether factors correlated to septum dislocation in newborns have quantitative significance for septum deviation demanding surgery in adults. The delivery circumstances of 95 patients operated upon for septum deviation were compared to those of 79 control subjects with straight septa. Patients and control subjects were born in the same area and at the same period of time. Eleven possible nose traumatizing factors were analyzed. No difference was found. There was, however, a male overrepresentation by 3:1 amongst the operated patients which may be explained by postnatal nose trauma. It is concluded that delivery circumstances have only minor influence on the number of adults demanding septum surgery.