Evaluation of bidirectional gut-brain axis and anorectal function in Parkinson's disease with constipation

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative movement disorder with prodromal and highly prevalent gastrointestinal (GI) symptoms, especially constipation. Although PD models suggest gut-brain axis dysfunction, the mechanistic underpinnings and their correlation with GI symptoms are poorly understood.

AIM

To examine the bidirectional gut-brain axis function in PD and correlate it with constipation severity, PD duration, and severity.

METHODS

Rectal sensory thresholds and afferent cortical evoked potentials (CEP) were assessed using a 4-ring EMG electrode probe. Efferent anal and rectal motor evoked potentials (MEPs) were obtained following transcranial and lumbosacral magnetic stimulation. Bowel symptoms were assessed by prospective stool diary. The CEP and MEP latencies, rectal sensory thresholds, and anorectal sensorimotor data were compared between PD subjects and age-adjusted healthy subjects.

KEY RESULTS

Twenty-five PD subjects with constipation (F/M = 6/19) and 20 healthy subjects (F/M = 14/6) were enrolled. The first and pain sensation thresholds were higher in PD subjects than healthy subjects (p < 0.002) but lost significance after adjustment for age. Age-adjusted rectal CEP and right-sided cortico-anal MEP latencies were prolonged in PD subjects compared to healthy subjects (p < 0.04). Also, half (4 of 8) age-adjusted spino-anal and rectal MEP latencies in PD subjects were significantly longer. In multivariate linear analysis, first rectal sensation and right-sided MEP latencies showed moderate correlation with constipation severity.

CONCLUSIONS & INFERENCES

Parkinson's disease is associated with significant bidirectional gut-brain axis dysfunction as evidenced by prolonged afferent and efferent neuronal signaling. Constipation severity in PD is correlated to abnormal rectal sensation and lateralized disturbance of efferent brain-gut signaling.

Diagnosis of amebic liver abscess and intestinal infection with the TechLab Entamoeba histolytica II antigen detection and antibody tests

A noninvasive diagnostic test for amebic liver abscess is needed, because amebic and bacterial abscesses appear identical on ultrasound or computer tomography and because it is rarely possible to identify Entamoeba histolytica in stool specimens from patients with amebic liver abscess. Here we report a method of detection in serum of circulating E. histolytica Gal/GalNAc lectin to diagnose amebic liver abscess, which was used in patients from Dhaka, Bangladesh. The TechLab E. histolytica II test (which differentiates the true pathogen E. histolytica from Entamoeba dispar) detected Gal/GalNAc lectin in the sera of 22 of 23 (96%) amebic liver abscess patients tested prior to treatment with the antiamebic drug metronidazole and 0 of 70 (0%) controls. After 1 week of treatment with metronidazole, 9 of 11 (82%) patients became serum lectin antigen negative. The sensitivity of the E. histolytica II antigen detection test for intestinal infection was also evaluated. Antigen detection identified E. histolytica infection in 50 samples from 1, 164 asymptomatic preschool children aged 2 to 5 years, including 16 of 16 (100%) culture-positive specimens. PCR analysis of stool specimens was used to confirm that most antigen-positive but culture-negative specimens were true-positive: PCR identified parasite DNA in 27 of 34 (79%) of the antigen-positive, culture-negative stool specimens. Antigen detection was a more sensitive test for infection than antilectin antibodies, which were detected in only 76 of 98 (78%) amebic liver abscess patients and in 26 of 50 (52%) patients with intestinal infection. We conclude that the TechLab E. histolytica II kit is a sensitive means to diagnose hepatic and intestinal amebiasis prior to the institution of metronidazole treatment.