Assessment of orocoecal transit time by means of a hydrogen (H2) breath test as compared with a radiologic control method

Emerging trends in nano-based antidiabetic therapeutics: a path to effective diabetes management

This review aims to provide an overview of nanoparticles for diabetes mellitus therapy. It explores the properties, synthesis and/or functionalization, mechanistic aspects, and therapeutics for diabetes and its complications.

Versatile Oral Insulin Delivery Nanosystems: From Materials to Nanostructures

Diabetes is a chronic metabolic disease characterized by lack of insulin in the body leading to failure of blood glucose regulation. Diabetes patients usually need frequent insulin injections to maintain normal blood glucose levels, which is a painful administration manner. Long-term drug injection brings great physical and psychological burden to diabetic patients. In order to improve the adaptability of patients to use insulin and reduce the pain caused by injection, the development of oral insulin formulations is currently a hot and difficult topic in the field of medicine and pharmacy. Thus, oral insulin delivery is a promising and convenient administration method to relieve the patients. However, insulin as a peptide drug is prone to be degraded by digestive enzymes. In addition, insulin has strong hydrophilicity and large molecular weight and extremely low oral bioavailability. To solve these problems in clinical practice, the oral insulin delivery nanosystems were designed and constructed by rational combination of various nanomaterials and nanotechnology. Such oral nanosystems have the advantages of strong adaptability, small size, convenient processing, long-lasting pharmaceutical activity, and drug controlled-release, so it can effectively improve the oral bioavailability and efficacy of insulin. This review summarizes the basic principles and recent progress in oral delivery nanosystems for insulin, including physiological absorption barrier of oral insulin and the development of materials to nanostructures for oral insulin delivery nanosystems.

Colonic transit studies: normal values for adults and children with comparison of radiological and scintigraphic methods

The sitz or plastic marker study for colonic transit has been around for many years. It is applicable where an X-ray machine exists, is widely used and is accepted as the gold standard for diagnosing constipation. Recently, radiopharmaceutical methods have been developed. The theme of this review is their possible roles in the assessment of paediatric bowel motility disorders in patients presenting to paediatric surgeons. This review presents data on total and segmental transit in normal adults and children and comparing the two techniques in adults. Reliability and reproducibility are presented. Normative data for colonic transit in adults and children are discussed and parameters for assessing abnormal transit are reviewed. Normal colonic transit takes 20-56 h. Plastic marker studies are more readily accessible, but the assessment may be misleading with current methods. Plastic markers show faster transit than scintigraphy. It is difficult to compare the two techniques because methods of reporting are different. Using scintigraphy, repeatability is good. Separation of normal from slow transit in the ascending colon is apparent at 24 and 48 h, but the determination of transit through the distal colon/rectum in adults may require studies of more than 7 days. In conclusion, plastic marker studies and scintigraphy show similar transit rates in young adults and children. However, scintigraphy has advantages of allowing transit through the stomach and small intestine to be measured and has proved useful in the diagnostic workup of children with intractable constipation.

Breath hydrogen test after a bean meal demonstrates delayed oro-cecal transit time in children with chronic constipation

OBJECTIVE

To evaluate oro-cecal transit time in children with chronic constipation.

METHODS

34 patients with chronic functional constipation age 3 to 13 years and 15 controls without constipation. Oro-cecal transit time was evaluated using the hydrogen breath test after ingestion of lactulose and after a standard meal of cooked beans. Total and segmental colonic transit times were measured with radiopaque markers.

RESULTS

Of 34 patients with chronic constipation 61.8% had increased total colonic transit time (>62 hours). Oro-cecal transit time measured with lactulose as substrate was similar (p=0.727) in constipated patients with increased colonic transit time (63.8+/-16.3 minutes), in constipated patients with normal colonic transit time (66.9+/-22.9 minutes), and in controls (65.3+/-15.5 minutes). Using a test meal of beans, the hydrogen breath test showed that oro-cecal transit time of constipated patients with increased total colon transit time was higher (252.4+/-23.2 minutes) than oro-cecal transit time of constipated patients with normal colonic transit time (227.7+/-39.6 minutes) or controls (205.3+/-23.3 minutes) (p<.05).

CONCLUSION

Hydrogen excretion in breath after a bean test meal showed delayed oro-cecal transit time in children with chronic constipation with abnormal total colonic transit time.

Measurement of gastrointestinal transit

An abnormality in transit is commonly considered to account for unexplained gastrointestinal (GI) symptoms. Since the symptoms of delayed transit overlap with those of accelerated transit, direct measurement of GI transit is needed to establish an accurate diagnosis. Similarly, since symptoms originating from one part of the gut may overlap with symptoms from another, localizing transit abnormality to one organ vs. another using direct measurement is an important part of diagnostic evaluations. Consequently, noninvasive tests of GI transit should be done early in the evaluation to guide therapy. We now have tools to measure transit accurately; results of transit tests often depend on the conditions selected for the test, so test results will match clinical expectations most closely when test conditions are selected to reproduce the circumstances for symptom production. This review describes the most commonly used methods for the measurement of GI transit including the gastric emptying test for some dyspeptic symptoms, small bowel transit test for dyspeptic symptoms and diarrhea, colonic transit test for constipation, and factors that influence the result of these studies. As we make progress in our understanding of the pathophysiology of transit disorders, the clinical usefulness of these diagnostic tests will be further enhanced.

No inhibition of gastro-intestinal propulsion after propofol- or propofol/ketamine-N2O/O2 anaesthesia. A comparison of gastro-caecal transit after isoflurane anaesthesia

BACKGROUND

Gastrointestinal motility may be considerably reduced by anaesthesia and or surgery resulting in postoperative ileus. Inhibition of propulsive gut motility is especially marked after an opioid-based technique. Little, however, is known of the gastrointestinal effects of the hypnotic propofol when given continuously over a longer period of time, which is the case in total intravenous anaesthesia (TIVA) and in intensive care sedation. We therefore set out to study the effects of a propofol-based nitrous oxide/oxygen anaesthesia (group PO) on gastro-caecal transit time. The results were compared with a propofol-ketamine technique (group PK) and an isoflurane-based anaesthesia (group I; each group n = 20).

METHODS

Gastro-caecal transit was determined by measurement of endexpiratory hydrogen concentration (ppm). Following gastral installation of lactulose at the end of the operation, the disaccharide was degraded by bacteria in the caecum, resulting in the liberation of hydrogen which was expired. A 100% increase in endexpiratory hydrogen concentration compared to the preinduction period was considered the end-point of gastro-caecal transit.

RESULTS

There was no significant difference with regard to gastro-caecal transit in the three groups of patients. In the propofol group mean gastro-caecal transit was 119 (+/- 50.6 SD) min, in the propofol-ketamine group it was 147 (+/- 57.4 SD) min, and in the isoflurane group transit time was 122 (+/- 48.6 SD) min.

CONCLUSION

The data suggest that propofol, even when given as a continuous infusion, does not alter gastrointestinal tract motility more than a standard isoflurane anaesthesia. The data may be particularly relevant to patients who are likely to develop postoperative ileus. They also suggest that in an ICU setting propofol does not alter gut motility more than a sedation technique with the analgesic ketamine.

Propofol sedation and gastric emptying in volunteers

BACKGROUND

The purpose of this study was to evaluate the effects of light propofol sedation on gastric emptying and orocecal transit time (OCT).

METHODS

Ten healthy male volunteers were studied on 2 occasions separated by at least 1 week and were randomly allocated to receive either propofol sedation or i.v. saline as a control. During propofol sedation the volunteers were sedated to grade 2-3 on a 5-grade scale. This was achieved by a propofol infusion of 5 mg kg(-1) h(-1) initially, which was then titrated down to a dose of 2.4+/-0.7 mg kg(-1) h(-1). Paracetamol absorption was used as an indirect measure of the rate of gastric emptying and OCT was determined by use of the hydrogen breath test after ingestion of raffinose. Student's t-test for paired samples was used and the results are presented as means+/-SD.

RESULTS

During propofol sedation the maximum concentration of paracetamol (Cmax) was 115+/-26.8 micromol/L, time to peak concentration (Tmax) 50+/-38.8 min, and the area under the curve during the first 60 min (AUC60) 4793+/-1538 micromol x min/L, versus Cmax 99+/-20.8, Tmax 69+/-41.9 and AUC60 3897+/-1310 during saline infusion. These differences were not statistically significant. OCT was significantly shorter during the control study, 180+/-32.4 min, than during propofol sedation, 217+/-64.9 min (P<0.05).

CONCLUSION

This study in volunteers has shown that gastric emptying of liquids seems uninfluenced by light propofol sedation. OCT was slightly prolonged during light propofol sedation.

Colonic transit time in constipated children: does pediatric slow-transit constipation exist?

In adults, slow-transit constipation is a well-established form of constipation with abdominal pain and an empty rectum on examination. Marker studies in these patients, mainly women, show a markedly slowed transit time in all colonic segments. No studies in constipated children are available that assess the existence of slow-transit constipation. In a prospective study, a total of 94 referred constipated pediatric patients, 63 boys and 31 girls (median age, 8.0 years), underwent colonic-transit-time measurements using radioopaque markers to evaluate the pattern of transit. In addition, orocecal-transit-time measurements using the hydrogen breath (lactulose) test, anorectal manometry, and behavior studies using the Child Behavior Checklist were performed in all children. Based on the upper limit (mean + 2 SD) of total colonic transit time (CTT) in constipated children, we arbitrarily separated patients into two groups. Children with CTTs > 100 h were said to have pediatric slow-transit constipation (PSTC), while patients with CTTs < 100 h were said to have normal- or delayed-transit constipation (NDTC). In 94 constipated children, PSTC was found in 24 children; in 70 children, total CTT was < 100 h (NDTC). Total and segmental CTTs were significantly prolonged in PSTC (median, 189 h; range, 104.4-384) versus NDTC (median, 46.8 h; range, 3.6-99.4) hours. No significant differences were found in orocecal transit time. Significant clinical differences in children with PSTC versus those with NDTC existed regarding nighttime soiling (71 vs. 11%); daytime soiling episodes (14 vs. 7 each week, median), and nighttime soiling episodes (5 vs. 0 each week, median); absent urge to defecate (33 vs. 14%); and palpable abdominal (71 vs. 39%) and/or rectal (71 vs. 13%) masses. All manometric parameters were comparable in the two groups, except for a significantly lower maximal squeeze pressure with PSTC. Using the Child Behavior Checklist, both groups differed significantly from controls (26 and 43%, respectively), with no significant differences in behavior problems found between the NDTC and the PSTC groups. In conclusion, based on objective marker studies, our findings suggest the existence of pediatric slow-transit constipation. This entity can be recognized by clinical features, most importantly nighttime soiling and a palpable rectal mass. The probability of PSTC with both of these symptoms was 0.82; in the absence of these two symptoms, it was 0.07. It is of interest that CTTs in PSTC are comparable with CTTs in adults with slow-transit constipation, although the clinical presentation is clearly different. Further studies are needed to investigate whether the prolonged CTT characterizes a distinct form of constipation in children or is an epiphenomenon of the underlying constipation itself. The mechanisms responsible for the slow transit in these children and the appropriate therapeutic approach need to be studied.

Nutrient malassimilation following total gastrectomy

BACKGROUND

The aim of the study was to elucidate the degree and the pathophysiology of abdominal symptoms, malnutrition and malassimilation after total gastrectomy.

METHODS

In 174 consecutive patients, with potentially curative total gastrectomy for gastric malignancy, subjective symptoms and objective parameters of malassimilation were evaluated.

RESULTS

Abdominal symptoms were present in 86% of the patients. In spite of a high daily calorie intake (median 37.8 kcal/kg body weight) mean body mass index had been decreasing since good health. Anaemia was found in 46%, sideropenia in 31% and oesophagitis in 26%. Mean faecal fat excretion was 17.4 (1.4) g/day and mean fat malassimilation 14.8% (1.1) of the intake. A shortened small-bowel transit was measured in 21.7% of the patients, and bacterial overgrowth was present in 37.7%.

CONCLUSIONS

Malassimilation post total gastrectomy seems to be multifactorial. Shortened small-bowel transit and subsequent dyssynchrony of pancreatic enzyme supply seem to be of major importance.

Lactulose hydrogen breath test in orocecal transit assessment. Critical evaluation by means of scintigraphic method

Orocecal transit time can be studied easily using the hydrogen breath test with lactulose, but the method has some important limitations. The orocecal transit time of 10 patients suffering from irritable bowel syndrome was measured twice, at a one-week interval, by breath test and scintigraphy simultaneously using an aqueous solution of 20 g lactulose containing 74 MBq of [99mTc]DTPA. Abdominal radioactivity and alveolar hydrogen values obtained every 5 min were noted and used to obtain the following: orocecal transit time by the two methods; ileocecal lactulose flow; total and per gram of lactulose hydrogen production; mean hydrogen concentration during the right colon filling; and measurement error of the breath test with respect to the scintigraphy. In the case of the breath test, the orocecal transit time intrapatient reproducibility was better (coefficient of variation = 13.5%) when a hydrogen threshold increment of 5 ppm was used; the best correlation with the scintigraphic measurement was observed at this threshold (r = 0.90, P < 0.001). The breath test overestimated orocecal transit time with the error correlating negatively and significantly with the total hydrogen production and, particularly, the mean hydrogen concentration (r = 0.79, P < 0.01): for a mean hydrogen concentration of more than 15 ppm, the error was negligible, while within this value there was a noticeable overestimation. To conclude, the lactulose hydrogen breath test is capable of giving an accurate measurement of orocecal transit time if a hydrogen threshold increment of 5 ppm is chosen and if the mean hydrogen concentration in the first 30 min of the right colon filling is taken into account.

Decreased orocaecal transit time, as measured by the exhalation of hydrogen, in hyperthyroid cats

Orocaecal transit time was assessed in healthy cats and cats with hyperthyroidism by means of the breath hydrogen test using a standard liquid meal with lactulose. The median transit time in 10 healthy cats was 98 minutes (range 60 to 150 minutes) and 90 minutes (range 75 to 150 minutes) in a repeated assessment. The median transit time in 10 cats with hyperthyroidism was 53 minutes (range 45 to 150 minutes) which was significantly more rapid (P < 0.05) than in the healthy cats.

The effect of short-term dietary fibre administration on oro-caecal transit time in dogs

The effect on oro-caecal transit time of addition of soluble (guar gum) and insoluble (wheat bran) fibre to diets fed to seven healthy dogs at levels that have been shown to reduce post-prandial hyperglycaemia was assessed. Oro-caecal transit time was measured by sequential analysis of exhaled breath hydrogen levels. Median oro-caecal transit times were 105 min (range: 45 to 135), 113 min (range: 53 to 203) and 105 min (range: 75 to 195) after administration of a 770 g standard meal of canned food alone, or with the addition of 7.7 g wheat bran or guar gum, respectively. There was no significant difference between the oro-caecal transit times (p = 0.964) for the different diets when the results for all the dogs were pooled. The difference between diets was statistically significant for both maximal post-prandial hyperglycaemia (p = 0.035) and area of post-prandial hyperglycaemia under the post-prandial glucose curve (p = 0.006).

Gastrointestinal pH and transit times in healthy subjects with ileostomy

Gastrointestinal pH in 11 healthy subjects with ileostomy was determined with a pH-sensitive, radiotransmitting capsule. Median pH was 7.0 in duodenum, dropped to pH 6.3 in the proximal part, but rose to 7.3 in the distal part of the small intestine. In five subjects the pH of the ileostomy effluents was determined with the pH capsule as well as with a pH meter. Median pH was 7.2 measured with the capsule and 7.4 with the pH meter. The difference between the results obtained with the two methods ranged from 0.1 to 0.3 pH units. The median gastrointestinal transit time of the capsule was 10.5 h (range 6.2-12.8 h). Gastric residence time was 0.6 h (range 0.2-3.8 h), and small intestinal transit time was 10.3 h (range 5.6-11.9 h). Thus the small intestinal transit time in ileostomates is slightly increased compared with values reported from studies on subjects with intact gut. However, no statistically significant correlation was found between the small intestinal transit time and the time elapsed after the creation of the ileostomy. We conclude that colectomy does not alter small intestinal pH but seems to increase the small intestinal transit time of single units.

Small bowel transit time measured by hydrogen breath test in patients with anorexia nervosa

The gastrocecal transit time was measured in 10 patients suffering from anorexia nervosa, using a lactulose hydrogen breath test, and was compared with the orocecal transit time in 11 healthy controls. One of the 10 patients and one of the 11 controls were excluded from this study because of no discernible increase in hydrogen excretion. The transit time was significantly prolonged in patients with anorexia nervosa compared with controls (117 min +/- 31 SD vs 81 min +/- 33 SD, P less than 0.02). In addition to delayed gastric emptying, which has hitherto been well known, the small bowel transit time was considered to be prolonged in patients with anorexia nervosa. Both these abnormalities seem to contribute to the development of various gastrointestinal symptoms in patients with anorexia nervosa.

pH-profile and regional transit times of the normal gut measured by a radiotelemetry device

The pH of the gut lumen was measured in 39 healthy persons using a pH-sensitive, radiotransmitting capsule. Thirteen persons were studied twice. The location of the capsule was determined by X-ray. The pH rose from 6.4 in the duodenum to 7.3 in the distal part of the small intestine. In 17 persons the pH dropped by 0.1-0.8 pH units during the last hours of the small intestinal transit. The pH was 5.7 in the caecum, but rose to 6.6 in the rectum. Gastric residence time was 1.1 h, small intestinal transit was 8 h, and colonic transit time was 17.5 h (median values). The results provide a firmer basis for prediction of the level, and the rate of release of active substance from pH-dependent sustained-release oral preparations.

The benefit of pancreatic enzyme substitution after total gastrectomy

The aim of the present study was to evaluate the effect of the pancreatic enzyme preparation Kreon on abdominal symptoms, bowel habits, faecal fat excretion and oro-caecal transit time in patients after total gastrectomy for carcinoma of the stomach with Roux-en-Y anastomosis. A hydrogen breath test was carried out in each patient to detect bacterial overgrowth. In a double-blind crossover trial, 15 patients were treated with either Kreon or placebo (3.6 g/day) in two test-periods each of seven days. During treatment with the active substance, the stool consistency became more solid (P less than 0.05). The number of bowel movements and the abdominal symptoms, however, remained statistically unchanged. Treatment with Kreon did not influence the oro-caecal transit time. Faecal fat excretion did not significantly decrease in the whole group of patients. However, in those patients with massive steatorrhoea (free and esterified fatty acids greater than 350 mmol/72 h; upper reference limit 60 mmol/72 h) a significant (P less than 0.05) reduction from a median excretion of 643 mmol/72 h to 501 mmol/72 h was seen. Such a decrease in faecal fat excretion did not occur in patients with steatorrhoea below this limit. Bacterial overgrowth or rapid upper intestinal transit were not over-represented in patients with a high-degree of steatorrhoea. We conclude that after total gastrectomy pancreatic enzyme substitution reduces massive steatorrhoea and improves stool consistency.

Measurement of small intestinal transit time in children

The lactulose hydrogen breath-test provides a non-invasive measure of mouth to caecum transit-time. Its use, particularly in children has not been thoroughly investigated. We have studied the effects on transit time of altering the lactulose concentration of the test solution, and of administering it in a liquid nutrient preparation. Concentration markedly affected transit-time; studies with an isotonic solution may be least affected by delayed gastric emptying, and so may reflect small bowel transit-time. Day-to-day variation was large, and was not reduced by altering lactulose concentration, or by using the liquid nutrient based test solution. There was no correlation between age and transit-time.

Orocoecal transit time in healthy and constipated children

Orocoecal transit time (OCTT), assessed by means of H2 breath test after lactulose and/or after a semisolid standard meal, was studied in normal and constipated children. Both control subjects and patients with constipation showed a significantly longer OCTT after a standard meal than after lactulose ingestion (p less than 0.01). Whereas the OCTT after lactulose did not differ in the two groups, the constipated patients had a significantly longer transit time after a standard meal when compared to controls (p less than 0.05). No correlation was observed within each group between the OCTT after a standard meal or after lactulose ingestion (r = -0.077; p greater than 0.01). These findings suggest that 1) measurement of the transit of a standard meal instead of a lactulose solution may offer more direct insight into the role of small intestinal transit of food, both in physiological and pathological conditions, 2) gastrointestinal segments other than colon may play a role in chronic non organic constipation of childhood.

Hydrogen (H2) breath excretion in peptic disease before and during treatment with ranitidine

Gastric juice pH, bacterial flora, and the H2 breath excretion were studied in patients treated with 150 mg ranitidine twice daily. The intragastric pH and bacterial contents rose during therapy. Before treatment upper respiratory tract bacteria were found in 4 of 23 patients and after 4 weeks of medication in 15 of 23. The median bacterial concentration was increased (p less than 0.01) and in five patients included bacteria normally found in the colon. Prolonged therapy for up to 12 weeks (n = 8) did not further change the bacteriologic pattern. Prophylactic treatment for 1 year (n = 3) showed gastric bacteria in high concentration, including Pseudomonas, in one patient. Postprandial H2 production remained unchanged after 4 (n = 23) and 12 (n = 7) weeks of therapy. In two of three patients treated prophylactically H2 excretion was increased after 1 year of medication. We conclude that acid reduction with ranitidine causes changes of the intragastric bacterial flora similar to those with other acid-reducing drugs in equipotent doses. The unchanged H2 breath test result after 4 and 12 weeks of treatment contradicts small-intestinal bacterial overgrowth. The elevated H2 excretion in two of the three patients after 1 year of treatment suggests the importance of a time factor in small-intestinal bacterial colonization.