Biomedical subjects

Lin Chang

Publications and source records attributed to Lin Chang.

49 records · Page 3Linked to original sources

PubMed2003

Brain responses to visceral and somatic stimuli in patients with irritable bowel syndrome with and without fibromyalgia.

OBJECTIVE: Symptoms of irritable bowel syndrome (IBS) and fibromyalgia (FM) commonly coexist. We hypothesized that one of the mechanisms underlying this comorbidity is increased activation of brain regions concerned with the processing and modulation of visceral and somatic afferent information, in particular subregions of the anterior cingulate cortex (ACC). METHODS: Regional cerebral blood flow (rCBF) was assessed in age-matched female IBS (n = 10) and IBS + FM (n = 10) subjects using H(2)(15)O positron emission tomography during noxious visceral (rectal) and somatic pressure stimuli. RESULTS: GI symptom severity was significantly higher in the IBS patients compared with the IBS + FM patients (p < 0.05). In addition, IBS + FM patients rated somatic pain as more intense than their abdominal pain (p < 0.05). Whereas the somatic stimulus was less unpleasant than the visceral stimulus for IBS patients without FM, the somatic and visceral stimuli were equally unpleasant in the IBS + FM group. Group differences in regional brain activation were entirely within the middle subregion of the ACC. There was a greater rCBF increase in response to noxious visceral stimuli in IBS patients and to somatic stimuli in IBS + FM patients. CONCLUSION: Chronic stimulus-specific enhancement of ACC responses to sensory stimuli in both syndromes may be associated with cognitive enhancement of either visceral (IBS) or somatic (IBS + FM) sensory input and may play a key pathophysiologic role in these chronic pain syndromes.

Adult↗

PubMed2003

Impact of sex and gender on irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a common functional bowel disorder characterized by abdominal pain and change in defecation pattern. This review addresses the topic of possible sex (genetic, biological) and gender (experiential, perceptual) differences in individuals with and without IBS. Several observations make the topic important. First, there is a predominance of women as compared to men who seek health care services for IBS in the United States and other industrialized societies. Second, menstrual cycle-linked differences are observed in IBS symptom reports. Third, women with IBS tend to report greater problems with constipation and nongastrointestinal complaints associated with IBS. Fourth, serotonin (5-HT3) receptor antagonist and 5-HT4 partial agonist drugs appear to more effectively diminish reports of bowel pattern disruption in women with IBS as compared to men. This review examines sex and gender modulation of gastrointestinal motility and transit, visceral pain sensitivity, autonomic nervous system function, serotonin biochemistry, and differences in health care-seeking behavior for IBS.

Autonomic Nervous System↗

PubMed2003

Effect of ghrelin on septic shock in rats.

AIM: To study the role of ghrelin in the late stage of septic shock in rats. METHODS: The rat model of septic shock was made by caecal ligation and perforation. At the time of operation ghrelin 10 nmol/kg was infused through femoral vein followed by a sc injection at 8 h after operation. Hemodynamic parameters including heart rate (HR), mean arterial blood pressure (MABP), LVdp/dtmax, and left ventricular end-diastolic pressure (LVEDP) in survival rats were measured at 18 h after surgery. Plasma glucose and lactate concentrations, plasma ghrelin level and myocardial ATP content were assayed. The mortality rate in rats with septic shock was also observed. RESULTS: Compared to that of septic shock group, MABP of rats in ghrelin-treated group increased by 33 % (P <0.01). The values of +LVdp/dtmax and -LVdp/dtmax increased by 27 % and 33 %, respectively (P <0.01), but LVEDP decreased by 33 % (P < 0.01). The plasma glucose concentration and myocardial ATP content increased by 53 % and 22 %, respectively, but plasma lactate concentration decreased by 40 % in ghrelin-treated rats (P < 0.01). The plasma ghrelin level in rats with septic shock was 51 % higher than that of rats in sham group, and was negatively correlated with MABP and blood glucose concentration (r=-0.721 and -0.811, respectively, P <0.01). The mortality rates were 47 % (9/19) in rats with septic shock and 25 % (3/12) in rats of ghrelin-treated group, respectively. CONCLUSION: Treatment with ghrelin could correct partly the abnormalities of hemodynamics and metabolic disturbance in septic shock of rats.

Adenosine Triphosphate↗

PubMed2002

Irritable Bowel Syndrome.

Because treatment of irritable bowel syndrome (IBS) patients can be frustrating to the clinician and patient as well, the physician should strive to gain the patient's confidence with a concise, appropriate work-up and by offering reassurance and education that IBS is a functional disorder without significant long-term health risks. First-line treatment should be aimed at treating the most bothersome symptom. Tricyclic antidepressants are superior to placebo in reducing abdominal pain scores, as well as improving global symptom severity. Loperamide is superior to placebo in managing IBS-associated diarrhea. Whereas fiber has a role in treating constipation, its value for IBS or, specifically, in the relief of abdominal pain or diarrhea associated with IBS is controversial. Although certain antispasmodics have demonstrated superiority over placebo in managing abdominal pain, none of these agents are available in the United States. Probiotic therapy using Lactobacillus plantarum has demonstrated superiority to placebo in improving pain, regulating bowel habits, and decreasing flatulence. As studied in a recent placebo-controlled prospective study, Chinese herbal medicines significantly improved bowel symptom scores and global symptom profile, and reduced IBS-related quality of life impairment. Some of the most promising emerging therapies in IBS revolve around targeted pharmacotherapeutic modulation of serotonin receptors (ie, 5-HT3 and 5-HT4 subtypes), which are involved in sensory and motor functions of the gut. Other investigational agents that are also being explored include cholecystokinin antagonists, alpha2-adrenergic agonists (eg, clonidine), serotonin reuptake inhibitors (eg, citalopram), and neurokinin antagonists. IBS is best understood through the biopsychosocial paradigm, and therefore, its effective management requires a comprehensive multidisciplinary approach based on patient education and reassurance, enhanced by diet recommendations and lifestyle modifications, and complemented by pharmacotherapy and psychosocial intervention in more severe cases.

Journal Article↗

PubMed2002

Condition-specific deactivation of brain regions by 5-HT3 receptor antagonist Alosetron.

BACKGROUND & AIMS: The 5-HT3 receptor (5-HT3R) antagonist Alosetron (Alos) reduces the symptoms of female patients with diarrhea-predominant irritable bowel syndrome (IBS); yet, the mechanism(s) underlying this effect remains incompletely understood. We determined the effect of Alos on regional cerebral blood flow (rCBF) in the absence and presence of rectal or sigmoid stimulation to evaluate 2 hypothesized mechanisms of therapeutic action: peripheral antinociception and inhibition of emotional motor system (EMS) regions in the brain. METHODS: Forty-nine nonconstipated irritable bowel syndrome (IBS) patients (26 female) received H(2)(15)O positron emission tomography (PET) brain scans before a randomized, placebo-controlled, 3-week trial with Alos (1-4 mg twice daily). PET scans were repeated after treatment in 37 completers. We assessed rCBF during baseline, rectal distention, and anticipation of undelivered rectal distention. The 3 conditions were repeated after a series of noxious sigmoid distentions. Rectal (45 mm Hg) and sigmoid (60 mm Hg) distentions were performed with a computer-controlled barostat device. RESULTS: Alos treatment, as compared with placebo, improved IBS symptoms and reduced rCBF in 5-HT3R containing regions of the EMS, but not in areas activated by pain. Reduction of rCBF appeared greatest in the absence of visceral stimulation, and was partially reversed by rectal or sigmoid distention. Symptom improvement across sessions was significantly correlated with rCBF decreases in the 5-HT3R-rich amygdala, ventral striatum, and dorsal pons. CONCLUSIONS: Reduction in IBS symptoms correlated with a drug-induced reduction in the activity of central autonomic networks mediating emotional expression that was maximal in the absence of nociceptive input.

Adult↗

PubMed2002

Gender differences in irritable bowel syndrome.

In the United States and other Western cultures, a greater number of women seek health care services for symptoms of functional pain disorders, including irritable bowel syndrome, than men. Recent clinical trials indicate that gender differences in responsiveness to drug therapy also occur. Several lines of inquiry have focused on explaining this gender-related difference due to the higher prevalence of these disorders in women. Evidence of a physiologic component is based on gender differences in gastrointestinal transit time, visceral sensitivity, central nervous system pain processing, and specific effects of estrogen and progesterone on gut function. Additional factors may play a role, including gender-related differences in neuroendocrine, autonomic nervous system, and stress reactivity, which are related to bowel function and pain. However, the link between these measures and gut motility or sensitivity remains to be clarified. Psychological characteristics, including somatization, depression, and anxiety as well as a history of sexual abuse, may also contribute to gender-related differences in the prevalence of irritable bowel syndrome. Although gender differences in the therapeutic benefit of serotonergic agents have been observed, less is known about potential differences in responsiveness to nondrug therapies for irritable bowel syndrome.

Colonic Diseases, Functional↗

PubMed2002

Enhanced preattentive central nervous system reactivity in irritable bowel syndrome.

OBJECTIVE: Irritable bowel syndrome (IBS) is a common functional disorder characterized by enhanced perceptual sensitivity and hypervigilance toward afferent signals from the viscera. We hypothesize that the increased responsiveness of IBS patients is a generalized phenomenon applying to stimuli other than visceral and attempt to demonstrate increased responsiveness to sounds as measured by the P1 scalp potential. METHODS: Event-related potentials were recorded from IBS patients and control subjects in an auditory task requiring detection of rare pitch targets in a designated ear. Visual words served as targets in an additional block. RESULTS: Compared to control subjects, IBS patients displayed a robust increase in the amplitude of the P1 scalp potential elicited by both attended and unattended sounds. CONCLUSIONS: Enhanced P1 indicates preattentive central nervous system dishabituation in response to repeated sounds. A generalized preattentive increase in central nervous system reactivity may be a feature that IBS shares with several anxiety disorders that frequently co-occur in these patients.

Acoustic Stimulation↗

PubMed2002

Utility of the Rome I and Rome II criteria for irritable bowel syndrome in U.S. women.

OBJECTIVES: Using interview data from a large, community-based sample of American women, we assessed the lifetime prevalence of irritable bowel syndrome (IBS) using questions consistent with the Rome II criteria, determined the sensitivity of Rome I and II in women diagnosed with IBS by their community physician, and identified whether there are differences in the patients identified by Rome I versus II. METHODS: A geographically diverse national probability sample of women diagnosed with IBS was identified and interviewed by telephone screening of a national, random digit dialing sample of households. A parallel national survey of adult females was conducted to determine the lifetime prevalence of IBS in U.S. women. Screening and interviews were conducted by experienced, female interviewers. IBS was defined by variations on the Rome I/II criteria. RESULTS: In the national community sample, lifetime IBS prevalence was 5.4% using Rome II. Full interviews were completed in 1,014 IBS patients. In the IBS sample, Rome I was significantly more sensitive than Rome II (84% vs 49%, p < 0.001). There was 47% agreement between Rome I and II. Of patients with IBS by Rome I, 58% met Rome II. Only 17.7% did not meet either Rome I or II. CONCLUSIONS: Rome I was more sensitive than Rome II in this community sample of female IBS patients. Rome I/II do not necessarily identify the same IBS patients. These findings have important implications for clinical research in IBS patients and raise questions about whether the Rome II criteria are sensitive enough to be useful in clinical practice.

Adult↗

PubMed2002

Is there a difference between abdominal pain and discomfort in moderate to severe IBS patients?

OBJECTIVES: The aims of this study were to: 1) determine the relative prevalence of self-reported pain-predominant and discomfort-predominant symptom patterns in irritable bowel syndrome (IBS) patients; and 2) test the hypotheses that pain-predominant patients report higher GI symptom severity, show higher psychological symptom severity, show worse quality of life, and demonstrate higher health care use. METHODS: A total of 256 consecutive ROME I-positive IBS patients with moderate to severe symptoms were classified according to whether they rated their predominant IBS symptoms as pain (n = 52), or as nonpainful discomfort (n = 128) on the Irritable Bowel Syndrome Quality of Life questionnaire. The validity of this classification scheme was confirmed by interview in a subsample of 45 patients. IBS-specific symptom patterns, psychometric assessment, and health-related quality of life measures were obtained using validated survey instruments. RESULTS: Contrary to the generally accepted notion that pain is the most predominant symptom in IBS, twice as many patients self-classified their symptoms as abdominal discomfort rather than abdominal pain. The classifications based on questionnaire data were shown to be valid in a subsample of subjects (n = 45) who underwent classification based on an independent, blinded, clinical interview (r = 0.77, p < 0.05). Pain and discomfort subgroups were similar in age, gender, predominant bowel habit, and overall GI symptom severity. In addition, the subgroups reported similar degrees of psychological distress, impaired quality of life, and increased patterns of health care use. CONCLUSIONS: Subgroups of moderate to severe IBS patients do report their predominant GI symptoms in terms of pain or nonpainful discomfort, regardless of severity of their overall GI symptoms or psychological symptoms. These findings are most consistent with a cognitive labeling bias of visceral sensations as either pain or discomfort.

Abdominal Pain↗

PubMed2002

[Study on forensic expertise of medical tangle].

OBJECTIVE: To study the characteristics of forensic expertise of medicial tangle, and explore the emphases and difficuties of forensic expertise. METHODS: The medical defect was classflied into the negliget defect, the technical defect, the administive defect, the learned defect and other defect. The 36 cases were analised according to the above-mentioned way. RESULTS: 86.11% of the 36 cases has the technical defect, 25% has the negliget defect and the administive defect. There were significant different between the our expertise opinion and Medical Tangle Expertise Committee's conclusion (P < 0.05, P < 0.01). CONCLUSION: The forensic expertise of medical tangle play the positive role in deal with the medical tangle cases, but there are many problems to further explore in forensic expertise.

Adolescent↗

PubMed2002

[Study on consistency of assessed results according to the Standard of Evaluated Injured Severity].

OBJECTIVE: To explore the consistency of assessed results according to Standard of Evaluated Injured Severity, finding out some factors that influenced appraisal conclusion. METHODS: 102 cases examined by Beijing Institute of Forensic Medicine and Science in 1998 were re-evaluated respectively by nine appraisers. RESULTS: The results showed that distinction of appraisal conclusion between appraisers in the same institute was small, but in different institute was big. The work experience and professional train were important to reduce errors. CONCLUSION: Standard of Evaluated Injured Severity strong take on character of profession. Veracity of assessed injured severity is related with unitive authoritative explanation, training and experience of appraiser.

Analysis of Variance↗

PubMed2002

Evolving pathophysiological model of functional gastrointestinal disorders: implications for treatment.

The physiological effects of psychological and physical stressors on gut function and brain-gut interactions are mediated by outputs of the emotional motor system in terms of autonomic, neuroendocrine, attentional, and pain modulatory responses. IBS patients with irritable bowel syndroms show an exaggerated responsiveness of this system manifesting itself in altered modulation of gastrointestinal motility and epithelial function, in alterations in the perception of visceral events, and in the associated conscious emotional responses. Animal models are being developed with high face and construct validity for functional visceral disorders that affect the gastrointestinal and urogenital tracts. These animal models suggest plausible targets for future drug development both in the periphery and in the central nervous system.

Animals↗

PubMedDate not supplied

The effect of life stress on symptoms of heartburn.

OBJECTIVE: Psychosocial stressors have been associated with exacerbations of symptoms in functional and inflammatory disorders of the gastrointestinal tract. The present longitudinal study tests the general hypothesis that life stressors can exacerbate symptoms in patients with chronic heartburn. METHODS: Sixty subjects with current heartburn symptoms were recruited by community advertisement and assessed for presence of stressful life events retrospectively over the preceding 6 months and prospectively for 4 months. Symptom severity by daily diary, quality of life, and psychological symptoms of anxiety, depression, and vital exhaustion were also measured. RESULTS: The presence of a severe, sustained life stress during the previous 6 months significantly predicted increased heartburn symptoms during the following 4 months. In addition, symptoms showed a strong, independent correlation with vital exhaustion. Affective and subjective stress ratings were not strongly related to heartburn severity; however, anxiety showed the strongest relationship to impaired quality of life and depression to heartburn medication use. CONCLUSIONS: As with other chronic conditions such as irritable bowel syndrome (IBS), heartburn severity appears to be most responsive to major life events and not an accumulation of more minor stressors or fluctuations in mood. In addition, vital exhaustion, which may in part result from sustained stress, may represent the psychophysiological symptom complex most closely associated with heartburn exacerbation. Potential mechanisms for these results include increased level and frequency of esophageal acid exposure, inhibition of gastric emptying of acid, or stress-induced hypersensitivity.

Adult↗