Utilization of short-chain fatty acids by colonic mucosal tissue strips. A new method of assessing colonic mucosal metabolism

BACKGROUND

Previous metabolic studies of the colonic mucosa have been done using isolated cells or small biopsy specimens.

METHODS

A new method for assessing the utilization of short-chain fatty acids in human colonic mucosal tissue strips considerably larger than routine samples was evaluated and compared with the method of isolated colonocytes. Human colonic mucosal strips and isolated human and rat colonocytes were incubated with acetate (C2), butyrate (C4), and hexanoate (C6), and oxidation rates obtained by quantifying the production of CO2.

RESULTS

The wet weight of strips was highly correlated with the production of CO2, and intersample coefficient of variance was <10%. The production of CO2 from the oxidation of C2, C4, and C6 was in the order of C2 > C4 > C6 for both strips and isolated human and rat colonocytes. The production of adenosine triphosphate (ATP) in strips and isolated human and rat colonocytes was in the order of C2 < or = C4 < or = C6. The Km value for the oxidation of butyrate to CO2 in strips (1.8 mmol/l) was several times higher than previously reported for isolated human and rat colonocytes (0.1-0.3 mmol/l).

CONCLUSIONS

This new method is highly reproducible and able to assess the metabolic activity of the colonic mucosa. The high Km value of butyrate oxidation in mucosal strips seems to reflect the in vivo Km value of colonocytes and shows the importance of a preserved anatomic structure in metabolic studies of the colonic epithelium. The low Km value for isolated colonocytes probably reflects the intracellular ability to oxidize butyrate. We propose that both isolated colonocytes and mucosal strips be used in studies of colonic mucosal metabolism. This method is relevant in disease states of the colon in which a disagreement prevails as to the ability to oxidize butyrate by colonocytes, such as in ulcerative colitis.

[Medicine and literature--interpretation and discussion of literary texts in medical education]

BACKGROUND

In medical education, using literary texts as a starting point for discussion and reflection, is now quite common. Lectures and seminars in literature and medicine have been given at the University of Oslo since 1996. We describe our pedagogical approach as a "thematic interpretation and discussion of literary texts", theoretically grounded in reader-oriented criticism and problem-based learning (PBL). This article describes the kind of learning taking place during analysis and discussion of literary texts among medical students.

MATERIAL AND METHODS

We evaluated a series of four elective seminars for first and second year students in the autumn 1998. We used qualitative approaches based on analysis of material from observations during seminars, reflections written by participants, and notes from a group interview at the end of the seminars.

RESULTS

Analysis and discussion of literary texts may give medical students: A better understanding of communicative aspects in the doctor-patient-relationship. Experience with interpretation of narratives and insight into how differently we may interpret a story. Awareness of aspects and dilemmas related to being a doctor. Understanding of how people may experience illness and health.

INTERPRETATION

Lectures and seminars on literary texts might be an important supplement to other practical or theoretical teaching for medical students.

The Danish National Hospital Register. A valuable source of data for modern health sciences

The Danish National Hospital Register (LPR) has collected nationwide data on all somatic hospital admissions since 1977, and since 1995 data on outpatients and emergency patients have been included as well. Numerous research projects have been undertaken in the national Danish context as well as in collaboration with international teams, and the LPR is truly a valuable source of data for health sciences, especially in epidemiology, health services research and clinical research. Nearly complete registration of somatic hospital events in Denmark is combined with ideal conditions for longterm follow-up due to the existence of a national system of unique person identification in a population of relative demographic stability. Examples of studies are provided for illustration within three main areas: I: Using LPR for surveillance of the occurrence of diseases and of surgical procedures, II: Using the Register as a sampling frame for longitudinal population based and clinical research, and III: Using the Register as a data source for monitoring outcomes. Data available from the Register as well as studies of the validity of the data are mentioned, and it is described how researchers may get access to the Register. The Danish National Hospital Register is well suited to contribute to international comparative studies with relevance for evidence-based medicine.

Interrater reliability of a Danish version of the Morgan Russell scale for assessment of anorexia nervosa

OBJECTIVE

To study the interrater reliability of a Danish version of the Morgan Russell scale for assessment of patients with anorexia nervosa, and subsequently to clarify the existing rating instructions.

METHOD

Ten patients undergoing treatment for anorexia nervosa at a regional center participated and had their interview videotaped. Two interviews were reserved for a training phase only. The group of raters comprised eight clinicians, and measures of interrater reliability were computed using intraclass correlation coefficient (ICC).

RESULTS

The ICC for the total score was good (0.79), while reliability for the single items varied from poor to excellent (0.14-0.99). Internal consistency as expressed by Cronbach's coefficient alpha was acceptable (0.74).

DISCUSSION

The Morgan Russell scale stands out as an easily applied and reliable measure of severity of anorexia nervosa, though the rating instructions need clarification in some items.

Reference values and biological variation for tumor marker CA 19-9 in serum for different Lewis and secretor genotypes and evaluation of secretor and Lewis genotyping in a Caucasian population

The concentration of the tumor marker CA 19-9 is influenced by the patient's secretor status and Lewis genotype. The aim of this study was to establish novel reference intervals for CA 19-9 in serum based on secretor and Lewis genotypes, to investigate the biological variation of CA 19-9, and to evaluate the utility of Lewis and secretor genotyping on a group of individuals with serologically defined Lewis phenotypes. CA 19-9 was measured in serum of 500 healthy individuals. Secretor and Lewis genotypes were determined by sequencing and PCR-cleavage methods. Significant differences were found between subgroups with different Lewis and secretor genotypes. Genotype-based reference intervals for CA 19-9 are presented. The upper reference limit for all individuals was 28.7 kilounits/L; for secretors and nonsecretors, the upper reference limits were 12.4 and 61.2 kilounits/L, respectively. The analytical imprecision (CVA) was 9.8%, the within-subject variability (CVI) was 15.8%, and the between-subject variability (CVG) was 102.2%. Good agreement was found between Lewis and secretor genotyping and conventional blood grouping. Genotype-based reference intervals may be a way to increase the clinical utility of CA 19-9. On the basis of the calculation of a critical difference for sequential values (significant at P Collapse

Key Words Collapse

MESH Headings

• Adult
• Aged
• Biomarkers, Tumor/blood
• CA-19-9 Antigen/blood
• Female
• Fucosyltransferases/genetics
• Genotype
• Humans
• Lewis Blood Group Antigens/genetics
• Male
• Middle Aged
• Point Mutation
• Polymerase Chain Reaction
• Reference Values
• Reproducibility of Results
• Sensitivity and Specificity
• White People/genetics
• Galactoside 2-alpha-L-fucosyltransferase

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Grants Collapse

Comparison of diarrhea induced by ingestion of fructooligosaccharide Idolax and disaccharide lactulose: role of osmolarity versus fermentation of malabsorbed carbohydrate

Whether carbohydrate malabsorption causes diarrhea probably depends on the balance between the osmotic force of the carbohydrate and the compensatory capacity of the colon to dispose of the carbohydrate by bacterial fermentation. The present study evaluated the specific role of the osmolarity by comparing the severity of diarrhea after ingestion of two nonabsorbable carbohydrates, the fructooligosaccharide Idolax and the disaccharide lactulose. Both carbohydrates are readily fermented by the colonic flora but differ in osmolarity, the osmotic force being twice as high for lactulose as for Idolax. Twelve subjects were given increasing doses (0, 20, 40, 80, 160 g/d) of Idolax and lactulose in a crossover design. Every dose level was administered for three days with intervals of one week. Stools were collected on the third day to determine 24-hr volume, concentrations of short-chain fatty acids, L- and D-lactate, residues of Idolax or lactulose, sodium, potassium, pH, osmolarity, and in vitro productions of organic acids. Measured by short-chain fatty acid and lactate formation in a fecal incubation system, the fermentation of Idolax and lactulose was identical and very rapid compared with a range of reference carbohydrates. A laxative effect of both Idolax and lactulose was demonstrated. The increment in fecal volume as a function of the dose administered was twice as high for lactulose (slope of the regression line = 7.3, r = 0.64, P< 10(-5)) as for Idolax (slope = 3.7, r = 0.51, P<10(-3)), i.e., isosmolar doses of lactulose and Idolax had the same effect on fecal volume. The variation in fecal volume was substantial (lactulose 80 g/day: 110-1360 g/day; Idolax 160 g/day: 130-1440 g/day). High responders had earlier and larger fecal excretions of the saccharide compared with low-responders. Fecal volume in carbohydrate-induced diarrhea is proportional to the osmotic force of the malabsorbed saccharide, even though all or the majority of the saccharide is degraded by colonic bacteria. The capacity to modify the diarrhea varies considerably from person to person and is associated with colonic saccharide disposal, whereas the variation in response to isosmolar amounts of different saccharides is small within the same individual.

Calibration of a reflectance pulse oximeter in fetal lambs for arterial oxygen saturations below 70%

OBJECTIVE

To calibrate a reflectance pulse oximeter developed at the Division of Perinatal Physiology, University Hospital of Zurich, for monitoring of oxygen saturations below 70%.

METHODS

Oxygen saturation measured noninvasively with the reflectance pulse oximeter in fetal sheep was compared with oxygen saturation of arterial blood samples measured by a conventional two-wavelength oximeter. Oxygen saturation was varied by stepwise reduction of the inspired oxygen concentration of the ewe.

RESULTS

A total of 58 data pairs was obtained from five fetuses, with a range of 10.9-73.5% for the reference method and 6.8-69.2% for the pulse oximetry oxygen saturation values. There was good correlation between the results obtained by the two methods (r2 = .89, P < .0001), with a 95% confidence interval of +/- 12.5%. The pulse oximeter showed a precision of 6.2% oxygen saturation.

CONCLUSION

The Zurich reflectance pulse oximeter offers valid measurements of oxygen saturation levels down to 10% oxygen saturation, and is therefore suitable for monitoring the fetus during delivery.

Human rectal absorption of short- and medium-chain C2-C10 fatty acids

BACKGROUND

Current knowledge on the colonorectal absorption of medium-chain fatty acids is limited. The purpose of the present study was to evaluate and compare the human rectal absorption of short- and medium-chain C2-C10 fatty acids in healthy volunteers.

METHODS

Dialysis bags containing 20 mmol x l(-1) of the fatty acids acetate, butyrate, hexanoate, octanoate, or decanoate in a phosphate-buffered (pH neutral) isoosmotic electrolyte solution were placed in the rectum for 30 min in 14 healthy volunteers. Absorption rates were calculated for all fatty acids, sodium, potassium, and water.

RESULTS

Absorption rates of the fatty acids acetate, butyrate, hexanoate, octanoate or decanoate were the same (1.9 +/- 0.1 = 2.5 +/- 0.2 = 1.7 +/- 0.2 = 1.9 +/- 0.2 = 2.2 +/- 0.1 micromol x cm(-2) x h(-1) (mean +/- standard error of the mean), respectively; P = 0.24).

CONCLUSIONS

Medium-chain fatty acids were absorbed in the human rectum at a rate similar to that for short-chain fatty acids. If results can be applied to the human colon, colonic absorption of medium-chain fatty acids could possibly become an important secondary site of absorption in abnormal intestinal conditions such as massive small-intestinal resection or malabsorption syndromes.

Standardized mortality in eating disorders--a quantitative summary of previously published and new evidence

Ten eating disorder (ED) populations were reviewed using the standardized mortality ratio (SMR) presenting new evidence for several studies. In eight of the ten samples, strong evidence (in one sample weak evidence and in one sample no evidence) supports an hypothesis of elevated SMR. We found strong evidence for an increase in SMR for anorexia nervosa (AN), whereas no firm conclusions could be drawn for bulimia nervosa (BN). Bias caused by loss to follow-up was quantified and found non-negligable in some samples (possible increase in SMR from 25% to 240%). We did not find a significant effect of gender or time period on SMR. Survival analysis showed a significant difference among the life-tables for males and females; female risk of death averaged 0.59% per year, whereas all male deaths occurred within the first 2 years after presentation. Weight at presentation had a highly significant effect on SMR, and lower weight at presentation was associated with higher SMR. Age at presentation exerted a significant unimodal effect on SMR; aggregate overall SMR was 3.6 for the youngest age group (< 20 years), 9.9 for those aged 20-29 years, and 5.7 for those aged > or = 30 years at presentation. Length of follow-up had a highly significant inverse effect on SMR; maximal SMR was 30 for female AN patients in the first year after presentation. A statistically significant increase in SMR was documented for at least up to 15 years after presentation. One study indicated a treatment effect on SMR. New evidence on causes of death suggests there are more deaths from suicide and other and unknown causes and fewer deaths related to ED than previously reported. Our findings have both research and clinical implications, with the most important clinical implication being the need for vigorous and well-directed treatment efforts from the initial presentation for treatment. An important research implication is that no single measure of mortality is sufficient; that is, only a combination of different statistics will maximize the available information.

Mycoplasma in urine and blood following catheterisation of patients undergoing vascular surgery

OBJECTIVES

The purpose of this investigation was to determine if mycoplasmas enter the bloodstream after urinary tract catheterisation in patients undergoing vascular surgery in order to evaluate the efficiency of the routine prophylactic antibiotic treatment.

DESIGN

Prospective study.

MATERIALS AND METHODS

A total of 100 patients (63 men and 37 women) undergoing elective vascular surgery had urine and blood cultures performed for mycoplasmas. Blood cultures were taken preoperatively after urinary tract catheterisation and the urine was collected during catheterisation. The median age of the patients was 67 years (range 42-87).

RESULTS

A total of 12 (12%), 5 men and 7 women, had a positive urine culture for mycoplasmas (One patient had Mycoplasma hominis and 11 had Ureaplasma urealyticum isolated). Their median age was 60 years (range 42-76). No blood cultures were positive for Mycoplasma.

CONCLUSIONS

Mycoplasmas do not enter the blood-stream after catheterization in sufficient amounts and sufficiently often to be detected by blood-cultures in this small patient sample. The number of vascular patients harbouring mycoplasmas in the urine was low and we found no indication for changes in the prophylactic antibiotic treatment based on these findings.

[Resectability of papillary and pancreatic cancer assessed by ultrasonography and computer tomography]

A retrospective study of 65 patients with postoperatively verified pancreatic or peripancreatic cancer was conducted. Before surgery all patients had ultrasonography (US) performed, and 46 patients had computed tomography (CT) performed as well. After operation description of pre-operative radiological findings has been compared to description of operative and pathological findings. Three of the 65 patients were excluded either because of lacking radiological descriptions (two patients) or uncertain operative findings (one patient). When both investigations were performed, they were carried out independently by two skilled radiologists without knowledge of the result of the other investigations. The following criteria were used for non-resectability encasement of splanchnic vessels, liver metastases, peritoneal thickening with ascites, and glandular enlargement. As assessed by US, 15 of 16 (94%) were truly predicted to be non-resectable, whereas only 21 of 38 (55%) were truly predicted resectable. CT was performed in 46 patients of which 19 of 21 (90%) were truly predicted non-resectable, and 17 of 21 (81%) were truly predicted resectable. It was not possible to perform a conclusive radiological investigation in eight of 62 (13%) cases by US, and four of 46 (9%) cases by CT. One patient was falsely predicted non-resectable by US and an additional one by CT. Both were falsely predicted non-resectable on suspicion of vessel involvement. Overall, invasion of vessels was the most common cause for non-resectability, at the same time this was the index of non-resectability that was most often not detected pre-operatively. US is reliable when predicting non-resectability. When resectable tumour is detected by US, supplementary investigations such as CT should be applied, and when necessary endoscopic procedures or laparoscopy as well. Hereby unnecessary laparotomies may be avoided. Care should be taken when suspecting papillary tumour; only 66% of these were detected by either of the two methods.

Markers of haemostatic activation before and after blood donation and plasmapheresis

BACKGROUND AND OBJECTIVES

Previous studies have reported signs of haemostatic activation after haemorrhage. The aim of this study was to measure sensitive markers for haemostatic activation after blood donation or plasmapheresis in healthy donors.

MATERIALS AND METHODS

Blood samples were drawn before as well as 5 min and 1 h after donation in 40 male donors, of whom 29 gave 1 unit of blood and 11 underwent plasmapheresis. Standard assays were used.

RESULTS

Plasma concentrations of the activation markers prothrombin fragment 1 + 2, thrombin-antithrombin complexes, and von Willebrand factor did not increase after blood or plasma donation.

CONCLUSIONS

In our opinion, these procedures are safe.

Diagnosing renal artery stenosis: a comparison between conventional renography, captopril renography and ultrasound Doppler in a large consecutive series of patients with arterial hypertension

The purpose of the study was to compare the positive and negative predictive values of conventional renography (Reno-A), captopril renography (Reno-B) and ultrasound Doppler (UD) with regard to the diagnosis renal artery stenosis. These three tests, and in addition a renal angiography, were performed in consecutively admitted patients with arterial hypertension, owing to either suspicion of renovascular hypertension or refractoriness to treatment. Patients with occlusion of a renal artery or a serum creatinine level higher than 300 mumol/l, or a previous investigation for renovascular hypertension at another hospital, were excluded from the analysis. The European Multicenter Study (EMS) criteria and local criteria for abnormal renography were compared. Of 131 patients, 28 had a renal artery stenosis (RAS) exceeding 50% reduction in diameter of the artery and 19 exceeding 70%. Using the EMS criteria for renography the predictive values of a negative test for a RAS more than 50% were 0.88 for Reno-A, 0.90 for Reno-B, 0.86 for changes from Reno-A to Reno-B, 0.92 for abnormalities either in Reno-A, Reno-B or changes from Reno-A to Reno-B, and 0.91 for UD. The corresponding values for a RAS more than 70% were 0.94, 0.97, 0.93, 0.98 and 0.96, respectively. The predictive values of a positive test were clearly lower, ranging from 0.20 to 0.75, but best when changes from Reno-A to Reno-B were used, 0.69-0.75. Using local criteria for renography the predictive values of a negative test were almost equal to those obtained by using the EMS criteria, but the predictive values of a positive test were slightly lower. It is concluded that conventional renography, captopril renography and ultrasound Doppler all are very good screening tests for renal artery stenosis, but the positive predictive values are clearly highest when using changes from conventional renography to captopril renography. It is suggested that captopril renography always should be performed when conventional renography is abnormal and vice versa to obtain the highest positive predictive value, on the assumption that total renal function is normal or almost normal, and that renal function is not absent in the affected kidney.

Use of neural networks to diagnose acute myocardial infarction. I. Methodology

We investigated several aspects of using neural networks as a diagnostic tool: the design of an optimal network, the amount of patients' data needed to train the network, the question of training the network optimally while avoiding overfitting, and the influence of redundant variables. The specific clinical problem chosen for illustration was the diagnosis of acute myocardial infarction, given only the electrocardiogram and the concentration of potassium in serum at the time of admission. We found that, in contrast to usual practice, the termination of the training process should be based on the generalization performance and not on the training performance. We also found that a principal component analysis can be used to eliminate redundant variables, thereby reducing the data space. The diagnostic performance of the neural network we used was 78%--superior to that of linear discriminant function analysis but similar to that of quadratic discriminant function analysis.

Use of neural networks to diagnose acute myocardial infarction. II. A clinical application

We investigated the ability of neural networks to diagnose acute myocardial infarction (AMI) from laboratory data only. Several networks were trained with different combinations of data obtained at admission and within the first 12 h and 24 h after admission. The data used included the electrocardiogram (ECG) and the concentrations in serum of potassium, creatine kinase B-subunit (CKB), and lactate dehydrogenase isoenzyme 1 for 250 patients with suspected AMI. Based on admission data, the correct diagnosis was predicted for 76% of the patients in the test group from the ECG data only, and the best combination of ECG results with other variables yielded correct diagnoses for 85% of the test group. Using all of the data available within 24 h, the network predicted the correct diagnosis for 99% of the test data. Almost the same high predictability was obtained by using only two CKB values-recorded at admission and within 12 h after admission-or by using just the latter one. Neural networks and quadratic discriminant analysis performed similarly, but the neural networks were more robust for combinations with many laboratory data.

Use of neural networks to diagnose acute myocardial infarction. II. A clinical application

We investigated the ability of neural networks to diagnose acute myocardial infarction (AMI) from laboratory data only. Several networks were trained with different combinations of data obtained at admission and within the first 12 h and 24 h after admission. The data used included the electrocardiogram (ECG) and the concentrations in serum of potassium, creatine kinase B-subunit (CKB), and lactate dehydrogenase isoenzyme 1 for 250 patients with suspected AMI. Based on admission data, the correct diagnosis was predicted for 76% of the patients in the test group from the ECG data only, and the best combination of ECG results with other variables yielded correct diagnoses for 85% of the test group. Using all of the data available within 24 h, the network predicted the correct diagnosis for 99% of the test data. Almost the same high predictability was obtained by using only two CKB values-recorded at admission and within 12 h after admission-or by using just the latter one. Neural networks and quadratic discriminant analysis performed similarly, but the neural networks were more robust for combinations with many laboratory data.

Use of neural networks to diagnose acute myocardial infarction. I. Methodology

We investigated several aspects of using neural networks as a diagnostic tool: the design of an optimal network, the amount of patients' data needed to train the network, the question of training the network optimally while avoiding overfitting, and the influence of redundant variables. The specific clinical problem chosen for illustration was the diagnosis of acute myocardial infarction, given only the electrocardiogram and the concentration of potassium in serum at the time of admission. We found that, in contrast to usual practice, the termination of the training process should be based on the generalization performance and not on the training performance. We also found that a principal component analysis can be used to eliminate redundant variables, thereby reducing the data space. The diagnostic performance of the neural network we used was 78%--superior to that of linear discriminant function analysis but similar to that of quadratic discriminant function analysis.

[Compression stockings as prevention of hypotension in Cesarean section during spinal anesthesia]

Inflatable splints and wrapping of the legs have been shown to be effective against hypotension during spinal anaesthesia for Caesarean section. The aim of this study was to investigate if compression stockings could have a similar effect. Thirty healthy mothers scheduled for elective Caesarean section were randomised to have either compression stockings or no stockings on before spinal anaesthesia. The stockings had a pressure effect of 54 mmHg. The women were preloaded with 20 ml isotonic NaCl one hour preoperatively. Hypotension was defined as either a decrease in systolic blood pressure to 80% of preoperative values or systolic blood pressure under 100 mmHg. Blood pressure was measured every second minute, and ephedrine 5 mg was given in the presence of hypotension. Two patients were excluded in the control group. There were no differences in demographic data, extension of blockade, and spinal injection to delivery time. Nine patients in the group with stockings had either no fall in blood pressure or a fall in blood pressure corrected with only 5 mg ephedrine. In the control group the corresponding number was four patients (p < 0.12). Ephedrine dose between zero and 20 minutes and total ephedrine dose was significantly lower in the group with stockings than in the control group (p < 0.038). Five patients in the control group experienced nausea, no patients in the study group had nausea (p < 0.013). In conclusion, compression stockings stabilised the blood pressure during Caesarean section in spinal anaesthesia and led to a significant smaller need for ephedrine.

[Percutaneous lumbar diskectomy]

The results after percutaneous lumbar discectomy were evaluated in 52 patients with low back pain corresponding to the L5 or S1 root. All patients were examined with a median follow-up time of 14 weeks. The patients were divided in two groups. Group 1: patients with an obvious indication for surgery (29 patients) and group 2: patients with a relative indication for surgery (23 patients). The follow-up results for patients in group 1 were comparable with the results after conventional discectomy. The results concerning follow-up low back pain in groups 1 and 2 were good or excellent in 69% and 43% of the patients respectively. The corresponding results for sciatica were 69% and 65% respectively. It is concluded that percutaneous lumbar discectomy is a possible alternative to conventional discectomy in selected patients.