R2 Response Research Articles

SU-FF-T-236: Dose Response of Ion Exchange Resin Beads

Purpose: To investigate the x-ray dose versus 1H NMR spin lattice relaxation (T1) response of ion exchange resin beads, with and without ferrous ions. Method and Materials: Strong acid cation exchange resin beads (Rohm and Haas, Amberlyst 15 Wet) were rinsed in distilled water and packed in plastic vials. Similar beads were treated to produce a 1 mM ferrous ion concentration inside the beads, then rinsed with distilled water, and finally packed in plastic vials. Sample vials were placed in a water phantom and exposed to 6 MV x-rays from 0 to 100 Gy. The T1 for each sample was measured in a 1.5 Tesla MRI unit. Beads from two manufacturing lots, Lot 1 and 2, were tested. Density of the bead samples was 1.10 g/cm3. Results: Vials with beads containing ferrous ions exhibited a linear dose versus R1 (i.e., 1/T1) response with slopes of 0.102 and 0.093 sec −1 Gy−1 for respectively Lot 1 and Lot 2 beads. Vials of Lot 1 beads containing no ferrous ions exhibited a linear dose versus R1 response with a slope of 0.083 sec−1 Gy−1. Vials of Lot 2 beads containing no ferrous ions showed an exponential increase in R1 of 2.4 sec−1 from 0 to 50 Gy with minimal increase in R1 from 50 to 100 Gy. Conclusion: For both bead lots, the beads containing ferrous ions exhibited similar linear dose versus R1 responses. Beads containing no ferrous ions exhibited significant, but different dose versus R1 responses. When the ferrous ions are present in the beads, a ferrous oxidation reaction appears to dominate the dose response. The results support the concept of using strong acid cation exchange resin beads containing ferrous ions to create a three dimensional dosimeter which can be evaluated using MRI.

Dose Response Of Pro-inflammatory Cytokines And Cytokine-inhibiting Reactions In Long Distance Running

Long distance running has been shown to increase pro-inflammatory cytokines and cytokine-inhibiting reactions, which also effects metabolism and cardiovascular regulation. However, the dose-responses of such processes are not sufficiently understood yet. PURPOSE To compare the immediate impact of distinct bouts of long distance running on TNF-α, TNF-α receptor 1 (TNF-α R1), TNF-α receptor 2 (TNF-α R2), and the ratio TNF-α R2: TNF-α R1. METHODS 6 male runners were randomly assigned to a trail-marathon (M) (44 ± 11.5 yrs, 176.8 ± 9.8 cm, 69 ± 10 kg) and a trail-10 km (K) (43 ± 10 yrs, 179.2 ± 1.5 cm, 77 ±2.7 kg). Venous blood samples were collected before and immediately after the run for measurements of TNF-α, TNF-α R1, and TNF-α R2, haemoglobin and haematocrit. Heart rate was monitored throughout the race. RESULTS Average running time was 4.5 times longer in the M compared to the K (270 ± 77 vs. 59 ± 1 min, t = 4.7, p <0.005), however running intensity as indicated by average heart rate was not significantly different between the M and the K (143 ± 8.3 vs. 139 ± 24 bpm, p >0.05). There was no significance differences in pre and post-race levels of haemoglobin in M (137.7 ± 9.1 vs. 145.7 ± 3 g.l−1, p >0.05), or K (145.7 ±11.2 vs. 149 ± 9.5 g.l−1, p >0.05). There was no significance difference in the pre and post-race haematocrit in M (41.7 ±2.1 vs. 41±1.7%, p>0.05), or K (41.3 ±1.1 vs. 41.7 ± 1.5 %, p >0.05). There was a significant reduction in TNF-α between pre and post samples among M (100.6 ± 17.2 vs. 93 ± 19.5 pg·ml−1, t = 2.9, p <0.05), but not among K (103.6 ± 94.3 vs. 105 ± 136 pg·ml−1, p >0.05). There was a significant increase in TNF-α R1 between pre and post samples among M (0.74 ± 0.25 vs. 1.7 ± 0.41 ng.ml−1, t = −10.4, p <0.005), and among K (0.67 ±0.04 vs. 1.07 ±0.05 ng.ml−1, t =−7.9, p <0.01). There was a significant increase in TNF-α R2 between pre and post samples among K (1.55 ± 0.39 vs. 1.84±0.45 ng.ml−1, t = −7.4, p <0.01), but not among M (1.47 ± 0.15 vs. 1.9 ± 0.22 ng.ml−1, p >0.05). There was a significant reduction in the ratio TNF-α R2: TNF-α R1 between pre and post samples among M (2.09 ±0.45 vs. 1.17 ± 0.35, t= 14.1, p <0.005), and among K (2.33 ± 0.69 vs. 1.71 ± 0.36, p <0.05). CONCLUSIONS The present results extend previous findings of different time courses in exercise related changes of the TNF-α R1, and TNF-α R2. They may serve as a hint for differences in the dose response of the TNF-a R1 and the TNF-α R2 with respect to the volume and the intensity of exercise.

Sensorimotor integration in patients with parkinsonian type multisystem atrophy

Sensorimotor integration is an essential feature of the central nervous system that contributes to the accurate performance of motor tasks. Some patients with multiple system atrophy with parkinsonian features (MSAp) exhibit clinical signs compatible with an abnormal central nervous system excitability to somatosensory inputs, such as action myoclonus or enhanced cutaneo-muscular reflexes. To investigate further the site where such dysfunction in sensorimotor integration takes place, we examined the inhibitory effects of a cutaneous afferent volley at two different levels of the motor system in 10 MSAp patients and in 10 age-matched healthy volunteers. Electrical digital nerve stimuli were given as the conditioning stimulus for the motor evoked potentials (MEP) elicited by transcranial magnetic stimulation in hand muscles, and for the blink reflex responses obtained in the orbicularis oculi muscles by supraorbital nerve stimulation. Intervals for the conditioning were 20 to 50 ms for the MEP and 90 to 110 ms for the blink reflex. The MEP was significantly inhibited in test trials in healthy volunteers, reaching a mean of 32% of the baseline values at the ISI of 35 ms. Significant inhibition occurred also in the blink reflex, in which the R2 response was a mean of 12% of baseline values at the ISI of 100 ms. The inhibitory effects were abnormally reduced in 8 patients on the MEP, and in 7 patients on the blink reflex. There were significant group differences between patients and control subjects in the size of the conditioned MEP and blink reflex. These results suggest that sensorimotor integration is abnormal in patients with MSAp in at least two central nervous system sites: the sensorimotor cortex, and the brainstem reticular formation.

Blink Reflex R2 Recovery Curves in Patients with Facial Palsy within Ten Days after Onset

The purpose of this study was to investigate the acute changes in blink reflex responses in patients with facial palsy. We used the blink reflex R2 recovery curves as an index of the excitability of the blink reflex neural circuit and evaluated the excitability of the blink reflex within 10 days after onset. Twelve patients with peripheral facial palsy were selected on condition that the degree of facial palsy was so mild that R2 responses of the blink reflex were measurable on the affected side, and they were compared with 12 healthy volunteers. Conditioning and test electrical stimuli were delivered on the affected side of the supraorbital nerve. Ipsilateral R2 response (iR2) of the blink reflex in patients was significantly enhanced at interstimulus intervals (ISIs) between conditioning and test stimuli from 100 to 1,000 ms, in comparison with the control subjects. These findings suggested hyperexcitability of the blink reflex neural circuit in patients with facial palsy. In addition to iR2, contralateral R2 response (cR2) in the patients was also significantly increased at ISIs of 100–1,000 ms to the same extent as the enhancement of iR2. All these findings suggested that the hyperexcitable changes developed in a common pathway of iR2 and cR2, but not in the ipsilateral facial motor neurons. It is suggested that the hyperexcitability of the neural circuit of the blink reflex during an acute period of facial palsy is an adaptive response to compensate for impaired facial motor function.

Brainstem reflex circuits revisited

Our current understanding of brainstem reflex physiology comes chiefly from the classic anatomical-functional correlation studies that traced the central circuits underlying brainstem reflexes and establishing reflex abnormalities as markers for specific areas of lesion. These studies nevertheless had the disadvantage of deriving from post-mortem findings in only a few patients. We developed a voxel-based model of the human brainstem designed to import and normalize MRIs, select groups of patients with or without a given dysfunction, compare their MRIs statistically, and construct three-plane maps showing the statistical probability of lesion. Using this method, we studied 180 patients with focal brainstem infarction. All subjects underwent a dedicated MRI study of the brainstem and the whole series of brainstem tests currently used in clinical neurophysiology: early (R1) and late (R2) blink reflex, early (SP1) and late (SP2) masseter inhibitory reflex, and the jaw jerk to chin tapping. Significance levels were highest for R1, SP1 and R2 afferent abnormalities. Patients with abnormalities in all three reflexes had lesions involving the primary sensory neurons in the ventral pons, before the afferents directed to the respective reflex circuits diverge. Patients with an isolated abnormality of R1 and SP1 responses had lesions that involved the ipsilateral dorsal pons, near the fourth ventricle floor, and lay close to each other. The area with the highest probabilities of lesion for the R2-afferent abnormality was in the ipsilateral dorsal-lateral medulla at the inferior olive level. SP2 abnormalities reached a low level of significance, in the same region as R2. Only few patients had a crossed-type abnormality of SP1, SP2 or R2; that of SP1 reached significance in the median pontine tegmentum rostral to the main trigeminal nucleus. Although abnormal in 38 patients, the jaw jerk appeared to have no cluster location. Because our voxel-based model quantitatively compares lesions in patients with or without a given reflex abnormality, it minimizes the risk that the significant areas depict vascular territories rather than common spots within the territory housing the reflex circuit. By analysing statistical data for a large cohort of patients, it also identifies the most frequent lesion location for each response. The finding of multireflex abnormalities reflects damage of the primary afferent neurons; hence it provides no evidence of an intra-axial lesion. The jaw jerk, perhaps the brainstem reflex most widely used in clinical neurophysiology, had no apparent topodiagnostic value, probably because it depends strongly on peripheral variables, including dental occlusion.

Relaxation enhancing properties of MnDPDP in human myocardium

To assess magnitude and duration of changes in myocardial longitudinal relaxation rate (R1) in humans following infusion of the manganese (Mn) releasing contrast agent MnDPDP (Mn-dipyridoxyl-diphosphate). Fifteen healthy volunteers were divided into three groups. After initial myocardial and liver R1 measurements using an inversion recovery (IR) turbo fast low-angle shot (FLASH) sequence at 1.5 Tesla, the groups were given different doses of intravenous MnDPDP: 5, 10 and 15 micromol/kg body weight, respectively, over 30 minutes. R1 measurements were then repeated at 1, 2, 4, 8, and 24 hours after the infusion ended. The left ventricular wall R1 prevalue was 0.98 second(-1) (+/-0.04). R1 increased on average (all 15 subjects) 0.41 second(-1) (+/-0.09). The increase was present one hour after the end of the infusion, remained relatively constant the next two hours, and then declined gradually. After 24 hours, there was still a moderate R1 elevation present, with an average R1-value of 1.16 (+/-0.05). There were only small differences in myocardial R1 responses between the three doses investigated, which was contrasted by a marked dose-response in liver tissue. MnDPDP gave a significant and prolonged rise in myocardial R1 even at a dose of 5 micromol/kg. The R1-values in the myocardium did not increase linearly with higher doses.

Blink reflex discloses CNS dysfunction in neurologically asymptomatic patients with systemic sclerosis

Objective: To investigate trigeminal-nerve, brain-stem, and brain function, in order to disclose a possible nervous system involvement in neurologically asymptomatic systemic sclerosis (SSc) patients. Methods: Using a standard electromyographic (EMG) technique, we recorded the early (R1) and late (R2) components of the blink reflex in 35 SSc patients with no history or signs of cranial-nerve impairment and 20 control subjects. SSc patients were classified as limited or diffuse SSc and also evaluated for disease duration, autoantibody pattern (ANA, ACA, Scl70) and skin score (by Rodnan modified method). Results: Whereas no SSc patients had an abnormal R1, six (18%) had delayed R2 responses. We found no correlation between R2 latency and clinical or laboratory data. Conclusions: Whereas previous studies reported both R1 and R2 abnormalities (reasonably due to trigeminal neuropathy) in symptomatic SSc patients, we found selective abnormalities of the R2 components in asymptomatic patients. The selective R2 abnormality is secondary to a central dysfunction, either because of a direct impairment of the polysynaptic circuits in the medulla, or because of a decreased cortico-reticular drive on these circuits. The lack of overt trigeminal symptoms in our patients favours a suprasegmental dysfunction, possibly due to microvascular lesions disseminated in the subcortical white matter.

Imaging of muscarinic acetylcholine receptor signaling in hippocampal neurons: evidence for phosphorylation-dependent and -independent regulation by G-protein-coupled receptor kinases.

We used the inositol 1,4,5-trisphosphate (IP3) biosensor, the pleckstrin homology (PH) domain of PLCdelta1 (phospholipase C) tagged with enhanced green fluorescent protein (eGFP-PH(PLCdelta)), to examine muscarinic acetylcholine (mACh) receptor regulation of phospholipase C/IP3 signaling in intact single hippocampal neurons in "real time." Initial experiments produced a pharmacological profile consistent with the presence of a predominant M1 mACh receptor population coupled to the IP3 response. To investigate M1 mACh receptor regulation, neurons were stimulated with approximate EC50 concentrations of the mACh receptor agonist methacholine before (R1) and after (R2) a short (60 sec) exposure to a high concentration of agonist. This resulted in a marked attenuation in the R2 relative to R1 response. Inhibition of endogenous GRK6 (G-protein-coupled receptor kinase) activity, by the introduction of catalytically inactive (K215R)GRK6, partially reversed the attenuation of agonist-induced responsiveness, whereas overexpression of wild-type GRK6 increased receptor desensitization. Manipulation of endogenous GRK2 activity through introduction of either wild-type or catalytically inactive GRK2 ((K220R)GRK2) almost completely inhibited agonist-stimulated IP3 production, implying a phosphorylation-independent regulation of M1 mACh receptor signaling, most probably mediated by a GRK2 N-terminal RGS-like (regulator of G-protein signaling) domain interaction with GTP-bound Galpha(q/11). Together, our data suggest a role for both phosphorylation-dependent and -independent regulation of M1 mACh receptors in hippocampal neurons.

Blepharospasm associated with multiple system atrophy: a case report and review of the literature

Although blepharospasm has been occasionally associated with parkinsonism, it has rarely been reported in patients with multiple system atrophy (MSA). We report a 65-year-old woman with MSA who developed blepharospasm seven years after onset, rendering her functionally blind. Clinical course and the findings of magnetic resonance imaging indicated cerebellar type MSA. The blink reflex studies showed prolonged R2 response and enhanced recovery cycle, indicating an increased excitability of the brainstem interneurons. These results suggest that pathophysiology of blepharospasm in MSA is similar to that of essential blepharospasm. Recognition of blepharospasm in MSA patients is important, as blepharospasm is a treatable feature in this otherwise intractable disorder.

The effect of water molecular self-diffusion on quantitative high-resolution MRI polymer gel dosimetry

In polymer gel dosimetry, magnetic resonance imaging (MRI) is used to determine the spin–spin relaxation rate (R2) which in turn can be correlated with absorbed dose to provide a map of the spatial distribution of the absorbed dose in the irradiated dosimeter. High accuracy, precision and reproducibility of these dose maps are essential. Moreover, for dose verification around brachytherapy sources used for intravascular brachytherapy, a high spatial resolution is required (typically 0.01–0.1 mm). To achieve these microscopic resolutions, strong imaging gradients are applied. The Brownian motion of water molecules in the presence of these strong magnetic field gradients causes an attenuation of the MR signal. When using a multiple spin–echo sequence, this may result in a significant deviation in the measured R2. The diffusion-related change in R2 at high resolutions was investigated experimentally and correlated with predictions that were obtained numerically and algebraically. Diffusion weighting is determined by the self-diffusion coefficient D, and imaging parameters, quantified by the b-factor. The b-factor was calculated for a multiple spin–echo sequence for different gradient strengths and gradient pulse durations. The variations in R2 that were observed when changing the matrix size and slice thickness are explained. It is shown that a linear correlation between the matrix size and the variation in R2 is based on the diffusion weighting caused by the read-out gradients and slice selective gradients. In conclusion, the essence of taking into account molecular self-diffusion to quantify variations in the measured dose–R2 response when using high-resolution MRI in polymer gel dosimetry is emphasized.

Investigation and analysis of ferrous sulfate polyvinyl alcohol (PVA) gel dosimeter

Ferrous sulfate (Fe(SO4)2) PVA gels were investigated for a range of absorbed doses up to 20 Gy using both magnetic resonance imaging (MRI) and spectrophotometry to determine R1 and optical density (OD) dose responses and G values. It was found that R1- and OD-dose sensitivities increased with O2 saturation or by the introduction of a freeze–thaw cycle during preparation of the PVA gel. The storage temperature of the Fe(SO4)2 PVA gel at −18 °C increased R1-dose sensitivity above that of gels stored at 5 °C. The addition of sucrose to the formulation was found to result in the largest increase in both R1- and OD-dose sensitivities. Fe(SO4)2 PVA gel with and without the addition of xylenol orange was demonstrated to have a G value of ∼20 ions/100 eV and with sucrose ∼24 ions/100 eV.

Selective suppression of late laryngeal adductor responses by N-methyl-D-aspartate receptor blockade in the cat.

Laryngeal adductor responses to afferent stimulation play a key role in airway protection. Although vital for protection during cough and swallow, these responses also must be centrally controlled to prevent airway obstruction by laryngospasm during prolonged stimulation. Our purpose was to determine the role of N-methyl-D-aspartate (NMDA) receptors in modulating early R1 responses (at 9 ms) and/or later more prolonged R2 responses (at 36 ms) during electrical stimulation of the laryngeal afferent fibers contained in the internal branch of the superior laryngeal nerve in the cat. The percent occurrence, amplitude, and conditioning of muscle responses to single superior laryngeal nerve (SLN) stimuli presented in pairs at interstimulus intervals of 250 ms were measured in three experiments: 1) animals that had ketamine as anesthetic premedication were compared with those who did not, when both were maintained under alpha-chloralose anesthesia. 2) The effects of administering ketamine in one group of animals were compared with increasing the depth of alpha-chloralose anesthesia without NMDA receptor blockade in another group of animals. 3) The effects of dextromethorphan (without anesthetic effects) were examined in another group of animals. In the first experiment, the occurrence of R2 responses were reduced from 95% in animals without ketamine premedication to 25% in animals with ketamine premedication (P = 0.015). No differences occurred in the occurrence, amplitude, latency, or conditioning effects on R1 responses between these groups. In the second experiment, the occurrence of R2 responses was reduced from 96 to 79% after an increase in the depth of anesthesia with alpha-chloralose in contrast with reductions in R2 occurrence from 98 to 19% following the administration of ketamine to induce NMDA receptor blockade along with increased anesthesia (P = 0.025). In the third experiment, R2 occurrence was reduced from 89 to 27% (P = 0.017) with administration of dextromethorphan while R1 response occurrence and amplitude did not change. In each of these experiments, NMDA receptor blockade did not have significant effects on cardiac or respiratory rates in any of the animals. The results demonstrate that NMDA receptors play an essential role in long latency R2 laryngeal responses to laryngeal afferent stimulation. On the other hand, early R1 laryngeal adductor responses are likely to involve non-NMDA receptor activation.

Bulbocavernosus muscle responses after suprapubic stimulation: Analysis and measurement of suprapubic bulbocavernosus reflex latency

Our objective was to describe pelvic floor responses with measurement of reflex latency after suprapubic mechanical stimulation. Twenty-one patients without neurological disease were studied. They were 14 women and seven men. The mean age was 51 (SD = 14.2). Motor responses were recorded with a needle electrode inserted in the left bulbocavernosus muscle. Stimulation was delivered with an electromechanical hammer, tapping directly on the suprapubic area. A polyphasic muscular response was always easily elicited in all patients. The man latency was 67.5 milliseconds (SD = 14.7). The reproducibility between the first and second mechanical responses was good with no statistical difference (r=0.966;P = 0.0001). In three patients who underwent cystometry, no rise in detrusor pressure was observed during mechanical stimulation of the suprapubic area. Our study clearly demonstrates a suprapubic bulbocavernosus reflex (SBR). Tapping the suprapubic area is a strong stimulus, reflexively mediated, used in the management of neurogenic bladder to determine a bladder contraction. However, the reflex consisting of pelvic floor muscle contraction after suprapubic stimulation was not specifically studied in humans. Many arguments can be put forth for a polysynaptic reflex (polyphasic response, habituation and short latency of the reflex, mean latency in the habitual values of R2 responses after electrical stimulation of the dorsal nerve of the penis). We hypothesize that the true stimulus is the stimulation of the bladder wall tensoreceptors, the integration level of the SBR is the sacral segments and the efferent limb the pudendal nerve, and afferent pathways could be conducted by pelvic nerve fibers. Competition between a preponderant (or exaggerated) SBR and a bladder contraction after suprapubic tapping may constitute an equivalent of detrusor-sphincter dyssynergia in some suprasacral bladders.

The stimulus intensity modifies the blink reflex recovery cycle in healthy subjects and in blepharospasm

Objective: The excitability of human brainstem interneurons is measured by the blink reflex recovery cycle and is abnormal in blepharospasm. We wondered whether the results of this paradigm depend on the stimulus intensity. Methods: We investigated the blink reflex recovery cycle in 13 healthy control subjects and in 13 patients with blepharospasm (7 of them treated with botulinum toxin) using 4 levels of stimulus intensity (5, 12, 19 and 26 mA) and two interstimulus intervals (ISIs, 150 or 250 ms). Results: In all groups the inhibition of the second R2 response was reduced with strong stimulus intensities: In controls, the inhibition of the second R2 decreased significantly (e.g. young controls, ISI 150 ms, from 89.6±15.6% at 5 mA to 21.9±49.7% at 26 mA, mean±standard deviation). In patients the R2 inhibition found at 5 mA was converted in an R2 facilitation at 26 mA, irrespective of the status of treatment. In addition, the patients’ results at 5 mA did not differ significantly from the controls’ results at 26 mA. Conclusions: The R2 inhibition and its sensitivity to detect abnormal interneuronal excitability depend on the stimulus intensity, which may act by modifying the excitability of the R2 interneurons.

Temperature dependence of polymer-gel dosimeter nuclear magnetic resonance response.

The purpose of this study was to find a physical-mathematical description capable to correct a polymer-gel dosimeter relaxation rate R2-dose response for different temperatures. Four different modifications of polymer-gel dosimeters were used in this study. Samples with polymer-gel dosimeter in glass test vessels were homogeneously irradiated by 60Co gamma photons. A multi-echo sequence with 16 equidistant echoes was used for evaluation of irradiated polymer-gel dosimeters. The sequence parameters were as follows: TR 2000 ms, TE 22.5-360.0 ms, slice thickness 5 mm, FOV 255 mm, one acquisition. The proposed description recommends to subtract R2 response of the nonirradiated dosimeter from the total R2-dose response. The relaxation rate for the irradiated dosimeter can be expressed as a function of temperature and dose. The temperature dependence has an exponential behavior in the measured range. The proposed description allows to correct the measured NMR R2-dose responses for different temperatures.

Le réflexe pubo-caverneux. Démonstration électrophysiologique

INTRODUCTION: In spinal cord injuries patients, tapping the suprapubic aera is a strong stimulus to ellicit detrusor contraction and can be used in the management of neurogenic bladder. This stimulation also determines a perineal muscles contraction. This striated response was mentionned in animal studies but never specifically analysed in men especially in normal subjects. AIMS OF THE STUDY: Our objective was to describe pelvic floor responses with measurement of reflex latency following suprapubic mechanical stimulation. METHODS: 21 patients without neurological disease were studied. They were 14 women and 7 men. Mean age was 51 (SD=14,2). Motor responses were recorded with a needle electrode inserted in the left bulbocavernosus muscle. Stimulation was delivered with an electromechanical hammer, tapping directly on the suprapubic aera. RESULTS: A polyphasic muscular response was always and easily elicited in all patients. Mean latency was 67,5 ms. (SD = 14,7). The reproducibility between the first and second mechanical responses was good with no statistical difference ( r=0,966 ; p=0,0001). DISCUSSION: Our study clearly demonstrates a suprapubic bulbocavernosus reflex (SBR). Many arguments can be retained for a polysynaptic reflex (polyphasic response, habituation and short latency of the reflex, mean latency in the habitual values of R2 responses following electrical stimulation of the dorsal nerve of the penis). We hypothetize that: the true stimulus is the stimulation of the bladder wall tenso-receptors; integration level of the SBR is the sacral segments and the efferent limb the pudendal nerve; afferent pathways could be vehicled by pelvic nerve fibers. CONCLUSION: Competition between a preponderant (or exaggerated) SBR and a bladder contraction following suprapubic tapping, may constitute a real functional outlet obstruction giving incomplete or complete retention in some suprasacral bladders. In normal subjects, SBR can be considered as a continence reflex with increase of perineal tone following the stimulation of the bladder wall tenso-receptors during stress.

Features of the blink reflex in individuals at risk for Huntington's disease.

The aim of the study was to correlate the features of the blink reflex (BR) with the genetic abnormalities and the clinical findings in patients with Huntington's disease (HD) and asymptomatic gene carriers. Twenty patients with HD and 20 relatives were studied. Mutation analysis was performed for the CAG expansion within the HD gene using HD 333-HD 447 as oligonucleotide primers. The BR was elicited transcutaneously by electrical stimulation of the right supraorbital nerve. The recovery curve of the R2 and R3 responses after a conditioning stimulus was evaluated. R2 latency and duration and R3 duration were significantly increased in HD patients and in presymptomatic carriers in comparison with controls; reduced R2 recovery was also clear in both HD and gene-carrier relatives. In HD patients, the R2 latency increase correlated significantly with the severity of facial chorea. The R2 abnormalities are probably caused by impaired suprasegmental control by the basal ganglia over brainstem interneurons, which may precede the onset of involuntary movements, probably conditioning the severity of facial chorea during development of the disease.

Influence of potassium on growth and yield of pigeon pea (Cajanus cajan)

An experiment was conducted during the rainy season of 1991 and 1992 to study gl.owlh i~lld yield pigeonpea [Cajanus cajan Millsp] to potassium application (0.25. 50 i111d 75 response of R1 (L.) kg/ ha). Application of K significantly increased the shoot dry weight, leaf-area indcx (I.AI). Ici~l-area duration and crop-growth rate. It also significantly increased the podslplant, 1,000-sccd wcighl, Ilarvest index and seed yield (qha). Application of 50 kg I(/l~a proved optimum tor growth ; I I I ~ yicltl I3;a;lmclers and the seed yield.

Iatrogenic trigeminal sensorimotor neuropathy resulting from local anesthesia: A case report

Chang WK, Mulford GJ. Iatrogenic trigeminal sensorimotor neuropathy resulting from local anesthesia: a case report. Arch Phys Med Rehabil 2000;81:1591-3. Trigeminal neuropathy resulting from local anesthetic injection has not been reported in the literature. We present a 49-year-old man with 8 months of unilateral facial sensorimotor deficits in the distribution of the trigeminal nerve, following a local anesthetic injection. His medical history was significant for resection of an ipsilateral tongue carcinoma 4 years earlier with only postsurgical dysarthria and no other neurologic deficits. Magnetic resonance imaging of the head and face showed postsurgical changes and ipsilateral atrophic muscles of mastication without evidence of infection or tumor recurrence. Electrodiagnostic evaluation revealed prolonged ipsilateral R1, ipsilateral and contralateral R2 responses of the blink reflex, and neurogenic electromyographic changes in ipsilateral masseter and temporalis muscles, consistent with ipsilateral trigeminal nerve injury. Although trigeminal neuropathies from various etiologies have been reported, this unique case offers another etiology to consider: iatrogenic trigeminal neuropathy secondary to local anesthetic injection. © 2000 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Laryngeal reflexomyographic responses in rabbits: a neurolaryngological study of glottal movement.

The role of the laryngeal reflex in glottal movement has been reported, but its mechanism remains unclear. To further investigate the neurophysiological characteristics of glottal movement, we recorded the laryngeal reflexomyographic responses (LRMRs) to electrical stimulation of the superior laryngeal nerve (SLN) in rabbits. The procedure involved simultaneous recording of the LRMRs from the thyroarytenoid muscles by means of bipolar hooked wire electrodes after electrical stimulation to the SLN. The results demonstrated characteristic patterns of the responses, consisting of R1 and R2, similar to those found in humans. The R1 response was obtained with a latency of 10.7 +/- 0.78 ms. The ipsilateral R2 response was obtained with a latency of 43.76 +/- 4.67 ms in all rabbits, and the contralateral R2 response with a latency from 42.6 to 50.2 ms in 4 rabbits. It was concluded that LRMRs may serve as a potential central laryngeal function test in the investigation of glottal movement control.