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Biomedical subjects

A M Drewes

Publications and source records attributed to A M Drewes.

At least 37 records · Page 2Linked to original sources
PubMed2001

Sensitivity and distensibility of the rectum and sigmoid colon in patients with irritable bowel syndrome.

BACKGROUND: Hyperalgesia to visceral stimuli is a biological marker of the irritable bowel syndrome (IBS). Abnormal pain processing is probably of most importance, but biomechanical abnormalities of the gut wall may also contribute to the findings. In the current study, we investigated the sensation of the gut to electrical stimuli as well as the distensibility of the rectum and sigmoid colon in IBS patients and a control group. METHODS: Nine patients with IBS and 11 controls entered the study. The pain threshold to electrical stimuli at the rectosigmoid junction was determined with bipolar electrodes integrated on the biopsy forceps for the endoscope. Subsequently, controlled distensions of the sigmoid colon and rectum were performed with a balloon integrated on a probe for impedance planimetry, providing the possibility to measure the cross-sectional area (CSA), wall tension and strain to different pressures together with the sensation ratings. RESULTS: The pain detection thresholds to electrical stimuli at the rectosigmoid junction were 12.5 (range 7-39) mA in controls and 7.5 (range 0.75-12) mA in IBS patients (P = 0.03). The calculated pressures at the pain detection threshold in the sigmoid colon were lower in the IBS patients (31.5 (range 5-58) versus 5 cm (range 5-25) water; P = 0.03), otherwise no differences were seen in sensation rating to the different distension pressures. The CSA was slightly higher in controls to the different pressures, whereas no differences between the groups were seen in strain and tension of the rectum and sigmoid colon. CONCLUSION: The visceral hypersensitivity in IBS seems to be related to alterations in the nervous system rather than biomechanical parameters such as the tension and strain of the gut wall. Treatment of pain in IBS should therefore be based on drugs with documented action on the nociceptive pathways in the central nervous system.

Adult↗
PubMed2001

Sensory and biomechanical responses to distension of the normal human rectum and sigmoid colon.

BACKGROUND: Visceral pain is a major clinical problem. The aim of the present study was to compare the pain and biomechanical responses to standardized distension of the human colon. METHODS: The relation between pain intensity and pressure, cross-sectional area (CSA) and tension-strain relations of the rectum and sigmoid colon were studied in 11 normal subjects following standardized distension using impedance planimetry. The bag was inflated stepwise with pressures up to 6 kPa. The subjects, who were blinded for the distension procedure, rated their pain intensity using an aggregate visual analogue score (VAS) combining the intensity of the feeling of air, urge to defecate and pain. RESULTS: The distensions produced an initial rapid increase in CSA followed by a phase of slow increase until a steady state CSA was reached after 0.5-1 min. Several phasic contractions (observed as short-term decreases in the CSA) were recorded in the rectum from the end of the rapid phase to the end of distension at pressures from 1 to 5 kPa. The CSA in the rectum and sigmoid colon was 3,706 +/- 426 mm(2) and 2,305 +/- 426 mm(2) at the maximum bag pressure of 6 kPa (F = 52.4, p < 0.001). The tension-strain relation did not differ between the normal rectum and sigmoid colon. The VAS score for every modality (air, defecation and pain) revealed an increase in intensity as a function of pressure. The VAS score in the rectum and the sigmoid colon as a function of tension and strain did not show any differences. CONCLUSIONS: The biomechanical properties in the sigmoid colon and rectum were alike. For a given wall tension and circumferential strain the sensibility seems equal in the rectum and the sigmoid colon. The observed difference in perception between the two segments was related to the greater CSA in the rectum.

Abdominal Pain↗
PubMed2000

Duration and distribution of experimental muscle hyperalgesia in humans following combined infusions of serotonin and bradykinin.

The present study examined distribution and duration of muscle hyperalgesia to pressure stimuli after intramuscular bolus-infusions of serotonin (5-HT, 20 nmol) and bradykinin (BKN, 10 nmol) in 10 volunteers. Infusions were given into the tibialis anterior (TA) muscle over 20 s with an inter-infusions interval of 3 min. Infusions of isotonic saline (NaCl, 0.9%) were given as control. Pain intensity was continuously scored on a visual analogue scale (VAS), and subjects drew the distribution of the pain areas on an anatomical map. Pressure pain thresholds (PPTs) were assessed with an electronic algometer at the injection site (10 cm below the patella), 2, 5, and 10 cm distal from the injection site, and at the ankle. Control assessments of PPTs were done at the contralateral TA and ankle. Skin sensibility was assessed with a Von Frey hair at the same sites. All measurements were done before and 5, 20, 40, and 60 min after infusions. The VAS-peak after BKN was significantly higher (P<0.05) compared with 5-HT and the second infusion of NaCl. The duration of the increase in VAS after 5-HT+BKN was significantly longer (P<0.05) compared with the infusions of NaCl. The local pain area after infusion of BKN was significantly larger (P<0.05) compared with 5-HT and control infusions. Cutaneous sensibility to tactile stimuli was not affected by any of the combinations. PPTs at the injection site and 2 cm (5, 20, and 40 min) were significantly decreased (P<0.05) after 5-HT+BKN compared with baseline and isotonic saline. In addition, PPTs were significantly decreased (P<0.05) after 5-HT+BKN at 5 cm (5 and 20 min) and 10 cm (5 min). Serotonin may enhance the effect of bradykinin in producing experimental muscle pain and muscle hyperalgesia to mechanical stimuli. The combination of serotonin and bradykinin can produce muscle hyperalgesia, lasted for up to 40 min and located within the muscle. No widespread hyperalgesia to the ankle and other leg (tested at 10 cm below the patella and ankle) was observed suggesting a predominant peripheral origin of the experimentally induced hyperalgesic stage.

Adult↗
PubMed1999

Pain produced by electric stimulation of the rectum in patients with irritable bowel syndrome: further evidence of visceral hyperalgesia.

BACKGROUND: Visceral hyperalgesia is most likely a phenomenon of substantial clinical importance and may also play a role in the pathophysiology of the irritable bowel syndrome (IBS). We investigated the manifestation of visceral hyperalgesia in IBS patients by nociceptive electric stimulation of the rectosigmoid junction and rectum. METHODS: Twelve IBS patients fulfilling the Rome criteria and 9 healthy controls were studied. Visceral single and repeated electric burst stimuli were applied with a bipolar electric stimulator inserted through the sigmoidoscope. The sensation (ST) and pain detection (PDT) thresholds were determined in response to single and repeated stimuli at the rectosigmoid junction, and PDT to repeated stimuli at four different positions in the rectum. Cutaneous single and repeated electric stimuli were applied to the lateral aspect of the foot, determining ST and PDT. RESULTS: Cutaneous stimulation showed no significant differences for ST and PDT between patients and controls. The rectosigmoid junction showed significantly lower ST for single stimuli (P<0.01) and a significantly lower PDT for single and for repeated stimuli (P<0.05 and P<0.02) in IBS patients. In the rectum the IBS patients had a significantly lower PDT than controls (P<0.001). CONCLUSIONS: For cutaneous electric stimulation no differences in the pain thresholds between the two groups were found, showing that there is no generalized hyperalgesia in IBS patients. The IBS patients had a specific decrease of the pain thresholds in the rectum and rectosigmoid junction, indicating visceral hyperalgesia. These results point to central visceral hyperexcitability as an important factor in the pathophysiology of IBS.

Abdominal Pain↗
PubMed1999

An experimental pain model based on electric stimulations of the colon mucosa.

BACKGROUND: Pain intensity and distribution related to diseases of the gut are important diagnostic indicators in gastroenterology. Experimental pain models provide a unique possibility for standardized activation of the nociceptive system, but only few human models exist. METHODS: An experimental pain model based on electric stimuli in the human colon was developed and applied. Eleven patients who were referred for surveillance colonoscopy due to earlier polyps in the colon were included. None had any abdominal pain complaints. The following areas were stimulated with 'single', 'repeated', or 'continuous' electric current: the cecum, the hepatic and splenic flexures, and the rectosigmoid junction. RESULTS: All subjects felt deep, diffuse pain during the stimulation, with referral to localized somatic structures. The pain detection thresholds after repeated stimuli were similar in the four areas. The threshold for single stimulation was higher than the threshold for repeated stimulation. Most reported pain in the lower and left site of the abdominal wall during stimuli at the splenic flexure and rectosigmoid junction. Stimuli at the right colon, however, resulted mostly in pain at the contralateral site of the abdomen. CONCLUSIONS: The presented model was robust and suitable for eliciting pain in different regions of the large intestine. The importance of temporal summation in visceral pain was shown. Mapping of the referred pain areas mimics clinical observations and has ontogenetic and anatomic consistency. The model may therefore improve the evaluation of pain in patients with diseases of the colon.

Abdominal Pain↗
PubMed1998

A quantitative HCV-PCR test for routine diagnostics.

The aim of this study was to develop a reliable and simple method for hepatitis C virus (HCV)-PCR using standard, automated laboratory equipment. HCV-RNA was extracted from serum and amplified in a single PCR with an internal standard. The PCR product was detected using fluoroimmunoassay. Quantification was based on external and internal standards. Linearity was observed over a wide range (10-10(7) geq). Mean inter and intra serial coefficients of variation were 35% and 23%, respectively. The limit of quantification was 1000 geq/ml based on intra and inter serial variations, while levels of 110 geq/ml were always detectable. Lower concentrations were intermittently positive. The ability to separate HCV-signals in healthy and infected persons was good, based on the distribution of HCV-signals from 353 random blood donors and 191 patient samples. To illustrate the applicability of the test, HCV-RNA quantification was performed in 11 patients during treatment with interferon alpha-2b. Ten of 11 patients showed a decline in HCV-RNA within the first few weeks of treatment. After four weeks most patients were still HCV-RNA positive but below the limit of quantification. The present method for quantification of HCV-RNA was shown to have sensitivity at the level of nested PCR techniques. Until now HCV-PCR has been complicated, time-consuming and costly, and therefore not suitable for routine diagnostics. The PCR method described here is easy to perform, fast and cost-effective.

Base Sequence↗
PubMed1998

Zopiclone as night medication in rheumatoid arthritis.

Sleep disturbances and related daytime complaints are frequent in rheumatoid arthritis (RA). The aim of the current study was therefore to evaluate the effect of a newer hypnotic on sleep structure and clinical parameters in RA. Forty outpatients were randomized to a two week treatment regimen with either 7.5 mg zopiclone or placebo at bedtime. Clinical examinations were performed before and after treatment and the degree of pain, fatigue, sleepiness, morning stiffness, and activities of daily living were assessed. Two sleep questionnaires were also completed weekly. Polysomnography was performed before the study and after 14 days of treatment. Recordings were evaluated using conventional sleep scoring as well as frequency analysis of the electroencephalography (EEG). Patients in the zopiclone group had subjective improvement of sleep, but otherwise no differences in pain score or the other clinical parameters were found. Conventional sleep assessments showed only minor changes during treatment, but frequency analysis demonstrated a shift from the lower towards the higher EEG frequencies in the active treatment group. Although the modulation of the EEG can represent a non-specific pharmacologic epiphenomenon, it might also reflect a disturbance of sleep microstructure. In conclusion, treatment with zopiclone may be of value for subjective sleep complaints in selected patients with RA, but it is doubtful whether hypnotics improve daytime symptoms in this patient group.

Adult↗
PubMed1998

Sleep in rheumatoid arthritis: a comparison with healthy subjects and studies of sleep/wake interactions.

Sleep complaints are frequent in patients with rheumatoid arthritis (RA) and sleep disturbances may contribute to pain and other daytime complaints. The aims of the current study were to compare ambulatory sleep recordings from consecutively selected patients with RA to those obtained in healthy controls, and to study the relationships between sleep structure and clinical symptoms. Sleep recordings were obtained from 41 out-patients with RA and 19 matched controls. All had clinical examinations and completed different questionnaires. Recordings were scored traditionally and, moreover, the electroencephalography (EEG) was subjected to frequency analysis. For the study of sleep-wake interactions in the patients, a graphical chain model was used. The patients had many sleep-related complaints. An increase in the number of periodic movements of the legs (PML) during sleep was seen in comparison with controls, but otherwise only minor differences were observed in classical sleep stages. Data from frequency analysis showed an increase in alpha (8-12 Hz)-EEG activity in sleep stages non-rapid eye movement (NREM) 2-4 in most sleep cycles. The statistical model demonstrated a complex but independent correlation between morning stiffness, pain and joint tenderness on the one hand, and awakenings, stage NREM2, slow-wave sleep and stage REM on the other, probably reflecting a relationship between sleep patterns and pain in RA. In conclusion, only the increase in PML and alpha-EEG activity distinguished the sleep in RA patients from that of healthy controls. However, the demonstrated interaction between daytime complaints and sleep patterns may increase the understanding and treatment of the disease. In future research, graphical chain models may improve our understanding of complex relationships between multiple variables.

Adult↗
PubMed1998

Performance of hepatitis C virus (HCV) antibody test systems in relation to HCV-RNA detection in the diagnosis of HCV infection.

BACKGROUND: Hepatitis C virus antibody (anti-HCV) test systems for screening and confirmation of blood donations have proved their value. The systems were later adopted for diagnosing patients suspected of hepatitis C. OBJECTIVES: 1) to study the clinical value of the recombinant immunoblot assay (RIBA) in routine diagnostics of patients suspected of HCV infection using HCV-PCR as the most definitive test and 2) to compare the performance of RIBA-2 with RIBA-3. MATERIALS: From May 1991 to August 1996 more than 4300 patients were tested for anti-HCV. All anti-HCV (EIA) positive patients were tested with RIBA-2 or RIBA-3 and HCV-PCR. RESULTS: We found no difference in the overall performance of RIBA-2 compared to RIBA-3. There was a tendency to fewer indeterminate results using RIBA-3 compared to RIBA-2 (5% vs. 9%), but this was not statistically significant. The NS5 band in RIBA-3 did not improve sensitivity or predictive value. Of RIBA-2 and RIBA-3 positive patients, 71% and 66% respectively were found to be HCV-RNA positive. Two samples that were negative using RIBA were HCV-RNA positive. CONCLUSION: RIBA testing in anti-HCV (EIA) positive patients added no clinically useful information to the screening results. We have therefore changed the diagnostic strategy so that all anti-HCV (EIA) positive patients are tested for HCV-RNA.

Hepacivirus↗
PubMed1997

The effect of cutaneous and deep pain on the electroencephalogram during sleep--an experimental study.

The interaction between sleep and pain has been insufficiently studied, and no experiments have investigated whether pathologic sleep patterns as seen in pain patients can be replicated experimentally by well-defined pain stimuli. An experimental model would therefore be valuable for further studies on the interaction between pain and sleep. In this study, three well-defined experimental stimuli (muscle, joint, and cutaneous pain) were applied during sleep, and the electroencephalogram (EEG) pattern was quantified. The pain stimuli were applied during slow-wave sleep in 10 healthy subjects. Using nine surface recordings, the EEG was sampled before and during pain stimuli. Frequency analysis was performed, resulting in 10 EEG features describing the responses to pain. During the muscle-pain stimulus an arousal effect was observed and a decrease in delta (0.5-3.5 Hz) and sigma (12-14 Hz) as well as increases in alpha 1 (8-10 Hz) and beta (14.5-25 Hz) activities were seen. During joint pain, however, more universal EEG changes were seen with a decrease in the lowest frequency bands [delta, theta (3.5-8 Hz) and alpha 1] and an increase in the higher frequencies [alpha 2 (10-12 Hz), sigma and beta bands]. No background EEG changes were observed during the cutaneous stimulus. There were several differences in the responses from the nine EEG channels, but no derivation seemed especially sensitive to detect the evoked changes. The study highlights the complexity of pain on the sleep EEG. The experimental model has shown that pain from different body structures, as well as signals from various EEG derivations, may give different responses in sleep microstructure.

Adult↗
PubMed1997

Experimental pain in the stomach: a model based on electrical stimulation guided by gastroscopy.

BACKGROUND: Abdominal pain is often variable in intensity and difficult to characterise due to its referred pain pattern. Clinical pain is furthermore confounded by various emotional and cognitive factors. AIMS: To develop and apply an experimental model to induce localised gastric pain. SUBJECTS: Twelve healthy male volunteers. METHODS: Stimulating electrodes were mounted on a biopsy forceps and electric stimuli were delivered during gastroscopy. Single, five repeated, and continuous stimuli were given at four locations in the stomach. Pain detection thresholds and pain intensities were assessed together with localisation of the referred pain area. RESULTS: Pain detection thresholds were higher in the prepyloric region compared with those obtained at the lesser and greater curvature. Increasing stimulus intensity resulted in augmented pain perception and repeated stimuli elicited pain at a lower stimulus intensity than single stimuli. Continuous stimuli evoked constant (33%), increasing (33%), or decreasing (33%) pain. The localisation of referred pain varied considerably in the subjects. CONCLUSIONS: The model seems relevant to study basic pain mechanisms elicited by localised stimuli in the stomach. The experimental data support the premise that a gastric focus should always be suspected in patients referred with different kinds of abdominal pain.

Abdominal Pain↗
PubMed1996

Ambulatory polysomnography using a new programmable amplifier system with on-line digitization of data: technical and clinical findings.

A new system for polysomnographic recording at home is presented. It consists of a 12 to 24-channel amplifier system with direct digitization of the polygraph signals using a portable computer. Sampling frequency, amplification and filter settings can be defined by the user, and the signals are evaluated at bedside. Technical testing proved a high signal/noise ratio, linear amplification and a good signal quality. Clinical testing of the first 100 recordings showed that they were acceptable for conventional sleep scoring in 98 cases. A comparison of two consecutive recordings was done in 9 healthy subjects and 11 patients with rheumatic disorders. Using conventional sleep staging, only a slight "first night effect" (FNE) was demonstrated in the sleep architecture. Power spectral analysis using autoregressive modeling demonstrated only a difference of power between the 2 nights in the beta (14.5-25 Hz) band. In conclusion, the usability and technical advantages make the system very suitable for ambulatory recordings and only a minimal FNE should be considered when results are evaluated.

Adult↗
PubMed1995

[Chronic lymphocytic and myeloid leukemia in the same patient].

A patient with chronic lymphocytic leukemia (CLL) treated with chlorambucil and prednisone developed chronic myelocytic leukemia (CML) five years later. An association between the two chronic leukemias has only rarely been reported. In the majority of cases the CLL preceded CML after which the malignancies coexisted morphologically in bone marrow and peripheral blood. In this case we report a suppression of CLL related symptoms and blood findings after the emergence of CML. However, immunophenotypic studies demonstrated a minor remaining population of CLL cells in the peripheral blood.

Aged↗
PubMed1995

Clustering of sleep electroencephalographic patterns in patients with the fibromyalgia syndrome.

Several electroencephalographic (EEG) abnormalities have been observed during sleep in patients suffering from the fibromyalgia syndrome (FMS). In this study, 12 patients with fibromyalgia and 14 control subjects had two polysomnographic recordings obtained at home. Data from the second night were subjected to blinded manual scoring as well as signal processing using linked or 'step-wise clustering for pattern recognition. In this procedure, a common learning set was generated using the spectral information in three 2 min EEG samples from each of the sleep stages selected from five patients with FMS and five controls. In this way, 17 characteristic EEG classes were defined. All 2 s EEG segments from the whole night from all subjects were then assigned to one of these classes. Five of the classes (dominated by 0.5-4.5 Hz activity) were more frequent in the control group, whereas three other classes (dominated by 8-11 Hz activity) were prevalent in the patient group. This trend was consistent in all sleep stages, although most striking in non-rapid eye movement (NREM) sleep. The predominance of these classes in the patient group may correspond to the alpha-EEG sleep anomaly previously reported in subjects with FMS. More importantly, as the EEG power in the lowest frequency range (prevalent in controls) probably is a marker for restorative sleep, the findings may reflect important aspects of sleep disturbances n subjects suffering from FMS, thereby contributing to some of the daytime symptoms in these patients.

Adult↗