Failure of rectal ornithine decarboxylase to identify adenomatous polyp status.

Rectal mucosal ornithine decarboxylase (ODC) activity has been reported to distinguish between patients with and without adenomatous polyps (AP). In the present investigation, ODC activity has been measured in 28 patients with AP and 34 patients without AP. To assess the intraindividual variation in ODC activity, repeat biopsies were performed on 11 patients. In addition, the effect of postbiopsy sample handling was investigated by storage of samples on either dry or wet ice during transport to the laboratory. The mean rectal mucosal ODC activity in patients with AP was 196.0 +/- 195.5, whereas that in AP negative patients was 182.2 +/- 320.5. The rectal mucosal ODC activity in patients with colorectal cancer was 388.2 +/- 581. Repeat samples in individuals were generally within the same range as the original samples. The method of sample transport did not significantly affect the level of ODC measured in a particular biopsy. Because of high variability in rectal mucosal ODC activity within the population, there was wide overlap in ODC values between those patients with and without AP in an unselected general population. Thus, the measurement of flat rectal mucosal ODC activity is not a good predictor of the presence or absence of AP. Additional studies of the factors affecting mucosal ODC activity are necessary before the potential clinical utility of the method can be realized in the general population.     

Improvement of cervical dystonia: possible role of transcranial magnetic stimulation simulating sensory tricks effect

Idiopathic cervical dystonia (ICD) is the most common form of focal dystonia. A characteristic and unique diagnostic feature is the presence of "sensory tricks", for example, a finger placed on the chin to neutralize the spasm. Although approximately 70% of patients with ICD experience effective sensory tricks, the exact mechanism of these tricks is still unknown. However, recent evidence suggests that higher sensorimotor integration processes are involved. A study using H2(15)O positron emission tomography demonstrated that the application of sensory trick stimulus, resulting in a near-neutral head position, led to an increased activation mainly of the superior and inferior parietal lobules (ipsilateral to head turn) and bilateral occipital cortex and to a decreased activity of the supplementary motor area and the primary sensorimotor cortex (contralateral to head turn). Since transcranial magnetic stimulation (TMS) is an experimental device with the ability to excite or depress the neural circuits, we hypothesize that the use of TMS of specific parameters to specific brain areas (as above) may produce an effect similar to sensory tricks resulting in the relief of spasms and the improvement of cervical dystonia.     

Dissecting the twin-arginine translocation pathway using genome-wide analysis

A recently discovered route for protein export, known as the twin-arginine translocation (Tat) pathway, has received much attention owing to several atypical characteristics that distinguish it from other transport mechanisms. For instance, recent evidence has clearly established that this pathway only transports folded polypeptides. Moreover, several studies have demonstrated a vital role for the Tat pathway in bacterial pathogenesis. In this review, we discuss genomic approaches that have been employed to determine the prevalence and capacity of the Tat system and how the information generated from these approaches is helping to connect Tat transport to bacterial physiology and virulence.     

Oscillopsia of peripheral vestibular origin. Central and cervical compensatory mechanisms

Eight patients with absent vestibular function categorized into four grades according to the disability they suffered from oscillopsia have been studied with a view to correlating its severity with the development of gaze stabilizing compensatory mechanisms. Eye movements were recorded while the following sinusoidal rotational stimuli were delivered: 1) trunk on head oscillation in the dark (COR); 2) head on trunk oscillation in the dark; 3) head on trunk and whole body (head and trunk) oscillation in the light in the presence of optic fixation. The COR was potentiated in all the patients regardless of their clinical status. Velocity gains (peak slow phase eye velocity/peak head velocity) during whole body rotation were significantly lower than head on trunk gains in the light in the better compensated patients. Since in the absence of vestibular function whole body rotation involves only the otokinetic system (OKN), this finding implies a depression of the OKN in these patients which can be corrected during head on trunk movements by virtue of a dynamic input from the neck. The results suggest that the processes of recovery from oscillopsia are dependent, in the main, upon the development of central mechanisms by means of which undesirable image movement across the retina is perceptually suppressed. Depression of OKN may be secondary to this perceptual rearrangement.     

Effects of morphine treatment on pro-opiomelanocortin systems in rat brain

In previous studies to determine whether chronic opiate administration might negatively feedback upon endogenous opioid systems in the CNS, investigators found no changes in steady-state concentrations of opioid peptides following morphine pelleting. However, since only steady-state levels were measured, it was still not clear whether morphine treatment altered the release and/or biosynthesis of opioid-containing neurons. The goal of the present study was to assess the effects of chronic morphine pelleting on the dynamics of β-endorphin (βE) biosynthesis in rats. Hence, at several times during a 7-day morphine treatment, concentrations of total βE-immunoreactivity (-ir), as well as chromatographically sieved forms of βE, were determined by RIA, and mRNA levels of pro-opiomelanocortin (POMC) were measured by a solution phase protection assay using a mouse or rat POMC³²P-labelled riboprobe. Concentrations of total βE-ir or different forms of βE-ir peptides (i.e. β-lipotropin,βE_1–31,orβE_1–27/βE_1–26) in the hypothalamus or midbrain following either 1 or 7 days of treatment were similar in morphine- and placebo-pelleted animals. However, a significant increase in total hypothalamic βE-ir was observed following 3 days of morphine pelleting; chromatographic analyses indicated that this was primarily due to a selective increase in the opiate inactive forms of βE, i.e.βE_1–27/βE_1–26. After 7 days of pelleting, morphine-treated animals tended to have lower POMC mRNA levels than those of placebo controls (20 to 50% decrease in different studies). The accumulation of hypothalamic βE-ir at 3 days, and the apparent decline in POMC mRNA levels at 7 days, lend support to the hypothesis that morphine negatively feeds back upon POMC neurons in the brain by inhibiting βE release and biosynthesis.     

The effect of eye/head deviation and visual conflict on visually evoked postural responses

Three interrelated experiments on visually evoked postural responses (VEPR) are presented to investigate the effect of lack of coplanarity between retinal and body coordinates (Experiment I) and the effect of directionally conflicting information in the visual stimulus. Experiment I showed that the direction of VEPR is modified by eye-in-orbit and head-on-trunk position signals, presumably of proprioceptive origin. Experiments II and III showed that VEPR can be critically suppressed by the presence of conflict within the visual stimulus (Experiment II: a linear, tagential component of visual motion acting in the opposite direction to the main angular component of a roll-motion display; Experiment III: a non congruent “improbable” visual motion parallax linear motion stimulus). A conceptual model of the postural system is presented, incorporating a gain control unit for the visuo-postural loop with inputs from the ocular/cervical proprioceptive system and from intra- and intersensory conflict detectors (comparators).     

Screening for depression among neuro-otology patients with and without identifiable vestibular lesions

The experience of depression and anxiety among a sample of 91 patients with complaints of vertigo or dizziness was assessed using a widely available screening instrument, the Hospital Anxiety and Depression Scale (HADS). Questionnaires to assess reported symptoms, self-esteem and social support were also administered. On the basis of clinical vestibular testing, 53% of participants were classified as having a labyrinthine disorder (canal paresis or positional vertigo), 22% as having a vestibular imbalance (spontaneous nystagmus or directional preponderance), and 251% as having no identifiable vestibular abnormality (negative test results). Based on the self-report measures using the screening instrument, 17% of the sample could be classified as depressed, and 29% as anxious. The presence of a vestibular lesion (based on clinical findings) was not associated with reported depression (F (3, 72) = 0.98, p = 0.41). The variables were entered into a hierarchical multiple regression analysis with depression as the dependent variable. A model emerged which accounted for 50% of the variance. Three variables comprised the final model: anxiety (beta = 0.44, p < 0.001), self-esteem (beta = 0.27, p < 0.01), and satisfaction with social support (beta = 0.25, p < 0.01). The results demonstrate the value of identifying psychosocial factors, as well as disease characteristics, among patients presenting at neurootology clinics. In particular, the findings highlight the importance of screening for emotional distress in this patient group, regardless of clinical test results or severity of self-reported symptoms.     

Children's service use during the transition to PCCM in two states

This study examines whether use of primary, preventive, or emergency care changed as primary care case management (PCCM) programs for children were implemented in Alabama and Georgia. Using claims data we track the same children over time, and control for geographic availability of Medicaid providers, which also changed over this period. A decline in use of all three types of care was found to be associated with PCCM implementation, with use of primary and preventive care falling below national averages and recommended use rates. Family difficulties in shifting to exclusive use of unfamiliar providers is the primary reason for the decline in use rates.