Assessing noise sources at synchrotron infrared ports.

Today, the vast majority of electron storage rings delivering synchrotron radiation for general user operation offer a dedicated infrared port. There is growing interest expressed by various scientific communities to exploit the mid-IR emission in microspectroscopy, as well as the far infrared (also called THz) range for spectroscopy. Compared with a thermal (laboratory-based source), IR synchrotron radiation sources offer enhanced brilliance of about two to three orders of magnitude in the mid-IR energy range, and enhanced flux and brilliance in the far-IR energy range. Synchrotron radiation also has a unique combination of a broad wavelength band together with a well defined time structure. Thermal sources (globar, mercury filament) have excellent stability. Because the sampling rate of a typical IR Fourier-transform spectroscopy experiment is in the kHz range (depending on the bandwidth of the detector), instabilities of various origins present in synchrotron radiation sources play a crucial role. Noise recordings at two different IR ports located at the Swiss Light Source and SOLEIL (France), under conditions relevant to real experiments, are discussed. The lowest electron beam fluctuations detectable in IR spectra have been quantified and are shown to be much smaller than what is routinely recorded by beam-position monitors.

Hindbrain GABA receptors influence parasympathetic outflow to the stomach.

Blockade of gamma-aminobutyric acid receptor function by direct microinjection of bicuculline into the nucleus ambiguous in cats produced a marked increase in gastric motility which was mediated by the vagus nerve. This effect was reversed by muscimol. These data indicate that the nucleus ambiguous may be an important brain site influencing gastric function and that the neurotransmitter controlling parasympathetic overflow from this nucleus to the stomach is gamma-aminobutyric acid.

Antroduodenal manometry in the evaluation of chronic functional gastrointestinal symptoms.

Intraluminal pressure in the gastric antrum and duodenum was studied in 44 children and adolescents referred for evaluation because of functional symptoms, including vomiting, abdominal distension, and abdominal pain. Manometric abnormalities were found in 39 patients (89%). Abnormalities during fasting included absence of the migrating motor complex; retrograde, phase 3-like episodes; increased frequency, decreased duration, and decreased amplitude of phase 3 episodes; tonic duodenal contractions; nonpropagated bursts of duodenal contractions; and consistently low-amplitude or absent contractions. Postprandial abnormalities included a phase 1-like pattern (postprandial hypomotility) and phase 3-like episodes (failure to induce a fed pattern). The presence or absence of the migrating motor complex was a predictor of disability. Parenteral alimentation was needed by only 4 of 28 patients with the migrating motor complex, but by 13 of 16 patients without the migrating motor complex (P less than .001). In 15 of 18 patients studied on consecutive days, oral cisapride was associated with increases in the number and amplitude of duodenal contractions after a complex-liquid meal (P less than .02). It is concluded that antroduodenal manometry is a useful technique that elucidates the underlying gastrointestinal motility disorder present in the majority of children and adolescents with severe functional symptoms.

Pharmacodynamics of racemic and S(-)-atenolol in humans.

The cardiovascular actions of racemic atenolol (RSATN) have been well characterized in humans, but the actions of S(-)-atenolol (SATN) when administered alone are unknown. In this study, responses of heart rate (HR) and Doppler-derived aortic blood flow profiles to upright treadmill exercise were compared after oral administration of 50 mg SATN and 100 mg RSATN in eight healthy, adult, male volunteers. After a single-blind, placebo run-in period, subjects were randomly allocated in a double-blind, crossover fashion to receive SATN and RSATN. Each study period was separated by a 7-day washout period. Multiple submaximal exercise tests were performed and data were collected over the 24 hours after each treatment. Both SATN and RSATN significantly (P < .05) blunted peak exercise HR by 38 +/- 3 and 37 +/- 3 beats/min, respectively. Aortic blood flow acceleration measured during peak exercise decreased after SATN and RSATN, by 13 +/- 4 and 13 +/- 3 m/sec2, respectively (P < .05). No difference in hemodynamic effect was observed between treatments. Pharmacodynamic parameters derived from plasma S(-)-atenolol concentration-effect (HR) curves after SATN, RSATN, and total atenolol plasma concentrations after RSATN did not differ significantly. Predicted maximum reductions in heart rate (Emax) and EC50 for S(-)-atenolol after SATN were 39.6 +/- 5.8 beats/min and 38.4 +/- 40.9 ng/ml versus 34.5 +/- 8 beats/min and 25.9 +/- 29.9 ng/ml for RSATN, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory and cardiovascular effects of intraventricular cholecystokinin.

Cholecystokinin (1-300 ng) was administered into the lateral brain ventricle of chloralose-anesthetized cats while monitoring tracheal airflow, arterial blood pressure, and heart rate. Dose-related increases in respiratory activity occurred in each animal tested, and were due to an increase in tidal volume. When 300-1000 ng of cholecystokinin was administered intravenously, no respiratory stimulant effect was observed. These results indicate that cholecystokinin acts in the brain to stimulate respiration.

Cervical diskography: analysis of provoked responses at C2-C3, C3-C4, and C4-C5.

BACKGROUND AND PURPOSE: Previous authors have described the locations of provoked responses to cervical diskography from C3-C4 to C6-C7, but we have found no description of the findings at C2-C3. This study was undertaken to analyze the sensations provoked during cervical diskography at C2-C3 and to compare the results with those provoked at C3-C4 and C4-C5. METHODS: The locations of diskographically provoked responses from 40 consecutive patients who had undergone C2-C3, C3-C4, and C4-C5 diskography were analyzed. Only intensely painful (> or = 7/10) and concordant responses were considered. Disk morphology on MR images and diskograms was also compared with the provoked responses. RESULTS: Eighteen subjects described either unilateral (n = 10) or bilateral (usually asymmetric) (n = 8) concordant pain at the craniovertebral junction in response to C2-C3 diskography. Nine subjects described either unilateral (n = 5) or bilateral (n = 4) neck pain during injection. Cephalalgia or head pain was provoked in 19 subjects, seven bilaterally. Four subjects described either unilateral (n = 3) or bilateral (n = 1) trapezius muscle and/or shoulder pain. Preliminary MR studies were not helpful, as most C2-C3 disks either appeared normal or exhibited nonspecific signs of degeneration. All disks exhibited either fissuring or extradiskal leakage of contrast material at diskography, regardless of the response provoked. CONCLUSION: Diskography at C2-C3 and C3-C4 frequently produces pain sensations in the head, craniovertebral junction, and neck. There is no correlation between C2-C3 disk morphology and the diskographically provoked response.

Magnetic resonance imaging of the thoracic spine. Evaluation of asymptomatic individuals.

We reviewed magnetic resonance imaging studies of the thoracic spines of ninety asymptomatic individuals to determine the prevalence of abnormal anatomical findings. This group included sixty individuals who had no history of any thoracic or lumbar pain and thirty individuals who had a history of low-back pain only. In addition, we reviewed imaging studies of eighteen patients who had an operatively proved herniation of a thoracic disc and studies of thirty-one patients who had been seen with thoracic pain. Sagittal T1-weighted spin-echo and axial multiplanar gradient refocused images at each disc level were interpreted by us (two neuroradiologists and two orthopaedic spine surgeons); we had no clinical information about the patients. Sixty-six (73 percent) of the ninety asymptomatic individuals had positive anatomical findings at one level or more. These findings included herniation of a disc in thirty-three subjects (37 percent), bulging of a disc in forty-eight (53 percent), an annular tear in fifty-two (58 percent), deformation of the spinal cord in twenty-six (29 percent), and Scheuermann end-plate irregularities or kyphosis in thirty-four (38 percent). This study documents the high prevalence of anatomical irregularities, including herniation of a disc and deformation of the spinal cord, on the magnetic resonance images of the thoracic spine in asymptomatic individuals. We emphasize that these findings represent roentgenographic abnormalities only, and any clinical decisions concerning the treatment of pain in the thoracic spine usually require additional studies.

Operative compared with nonoperative treatment of a thoracolumbar burst fracture without neurological deficit. A prospective, randomized study.

BACKGROUND: To our knowledge, a prospective, randomized study comparing operative and nonoperative treatment of a thoracolumbar burst fracture in patients without a neurological deficit has never been performed. Our hypothesis was that operative treatment would lead to superior long-term clinical outcomes. METHODS: From 1994 to 1998, forty-seven consecutive patients (thirty-two men and fifteen women) with a stable thoracolumbar burst fracture and no neurological deficit were randomized to one of two treatment groups: operative (posterior or anterior arthrodesis and instrumentation) or nonoperative treatment (application of a body cast or orthosis). Radiographs and computed tomography scans were analyzed for sagittal alignment and canal compromise. All patients completed a questionnaire to assess any disability they may have had before the injury, and they indicated the degree of pain at the time of presentation with use of a visual analog scale. The average duration of follow-up was forty-four months (minimum, twenty-four months). After treatment, patients indicated the degree of pain with use of the visual analog scale and they completed the Roland and Morris disability questionnaire, the Oswestry back-pain questionnaire, and the Short Form-36 (SF-36) health survey. RESULTS: In the operative group (twenty-four patients), the average fracture kyphosis was 10.1 degrees at the time of admission and 13 degrees at the final follow-up evaluation. The average canal compromise was 39% on admission, and it improved to 22% at the final follow-up examination. In the nonoperative group (twenty-three patients), the average kyphosis was 11.3 degrees at the time of admission and 13.8 degrees at the final follow-up examination after treatment. The average canal compromise was 34% at the time of admission and improved to 19% at the final follow-up examination. On the basis of the numbers available, no significant difference was found between the two groups with respect to return to work. The average pain scores at the time of the latest follow-up were similar for both groups. The preinjury scores were similar for both groups; however, at the time of the final follow-up, those who were treated nonoperatively reported less disability. Final scores on the SF-36 and Oswestry questionnaires were similar for the two groups, although certain trends favored those treated without surgery. Complications were more frequent in the operative group. CONCLUSION: We found that operative treatment of patients with a stable thoracolumbar burst fracture and normal findings on the neurological examination provided no major long-term advantage compared with nonoperative treatment.

Fungal infections of the spine. Report of eleven patients with long-term follow-up.

BACKGROUND: Fungal infections of the spine are noncaseating, acid-fast-negative infections that occur primarily as opportunistic infections in immunocompromised patients. We analyzed eleven patients with spinal osteomyelitis caused by a fungus, and we developed suggestions for treatment. METHODS: All patients with a fungal infection of the spine treated by the authors over a sixteen-year period at three teaching institutions were evaluated. There was a total of eleven patients. Medical records and roentgenograms were available for every patient. Long-term follow-up of the nine surviving patients was performed by direct examination by the authors or by the patient's primary physician. RESULTS: For ten of the eleven patients, the average delay in the diagnosis was ninety-nine days. Nine patients were immunocompromised secondary to diabetes mellitus, corticosteroid use, chemotherapy for a tumor, or malnutrition. The sources of the spinal infections included direct implantation from trauma (one patient), hematogenous spread (four patients), and local extension (two patients). The infection followed elective spine surgery in three patients, and the cause was unknown in one. Paralysis secondary to the spine infection developed in eight patients. Ten patients were treated with surgical debridement. All eleven patients were treated with systemic antifungal medications for a minimum of six weeks. One patient died of generalized sepsis at thirty-three days, and another patient died of gastrointestinal hemorrhage at five months. After an average of 6.3 years of follow-up, the infection had resolved in all nine surviving patients. CONCLUSIONS: Treatment of fungal spondylitis is often delayed because of difficulty with the diagnosis. Delay in the diagnosis led to poorer results in terms of neurologic recovery in our study. Performing fungal cultures whenever a spinal infection is suspected might hasten the diagnosis. Patients should be given a guarded prognosis and informed of the many possible complications of the disease.

A prospective, randomized, double-blind evaluation of trigger-point injection therapy for low-back pain.

The efficacy of trigger-point injection therapy in treatment of low-back strain was evaluated in a prospective, randomized, double-blind study. The patient population consisted of 63 individuals with low-back strain. Patients with this diagnosis had nonradiating low-back pain, normal neurologic examination, absence of tension signs, and lumbosacral roentgenograms interpreted as being within normal limits. They were treated conservatively for 4 weeks before entering the study. Injection therapy was of four different types: lidocaine, lidocaine combined with a steroid, acupuncture, and vapocoolant spray with acupressure. Results indicated that therapy without injected medication (63% improvement rate) was at least as effective as therapy with drug injection (42% improvement rate), at a P value of 0.09. Trigger-point therapy seems to be a useful adjunct in treatment of low-back strain. The injected substance apparently is not the critical factor, since direct mechanical stimulus to the trigger-point seems to give symptomatic relief equal to that of treatment with various types of injected medication.

Anterior decompression, structural bone grafting, and Caspar plate stabilization for unstable cervical spine fractures and/or dislocations.

Fourteen patients who sustained acute cervical spine fractures and/or dislocations with associated posterior ligamentous disruption had anterior decompressions, structural bone grafting, and anterior Caspar plate stabilization. With an average 30-month follow-up, no patient has had loss of fixation. Despite criticism raised from biomechanical testing, the Caspar anterior plate system (Aesculape, Tuttlingen, Germany) may be added to structural bone grafting of unstable cervical fractures and/or dislocations, yielding an in vivo solid construct, which obviates the need for simultaneous posterior stabilization.

Thoracic discography in healthy individuals. A controlled prospective study of magnetic resonance imaging and discography in asymptomatic and symptomatic individuals.

STUDY DESIGN: A prospective case-control investigation. OBJECTIVES: To determine the responses to thoracic discography of asymptomatic individuals. SUMMARY OF BACKGROUND DATA: Literature regarding lumbar and cervical discography reveals that even morphologically abnormal discs often are not painful, whereas painful discs typically exhibit anular or endplate disruption. METHODS: Ten adult lifelong asymptomatic volunteers, ages 23 to 45 years, underwent magnetic resonance imaging of the thoracic spine, followed by four-level discography. Provocative responses were graded on a scale of 0 (no sensation) to 10 (extreme pain or pressure), and filmed discs were graded using a modified Dallas scheme. Concomitantly, 10 nonlitigious adults (6 men and 4 women, ages 31 to 55 years) experiencing chronic thoracic pain were similarly studied as a control group. RESULTS: The mean pain response in the asymptomatic volunteers was 2.4/10. Three discs were intensely painful (scores of 7/10, 8/10, 10/10), with all three exhibiting prominent endplate irregularities and anular tears typical of thoracolumbar Scheuermann's disease. On discography, 27 of 40 discs were abnormal, with endplate irregularities, anular tears, and/or herniations. Ten discs read as normal on magnetic resonance imaging showed anular pathology on discography. In the group with chronic thoracic pain, the average pain response was 6.3/10 (P < 0.05). Of the 48 discs studied, 24 were concordantly painful, with a pain response of 8.5/10 (P < 0.05); 17 had nonconcordant pain/pressure, with an average pain of 4.8/10 (P < 0.05); and 5 had no response. On magnetic resonance imaging 21 of the 48 discs appeared normal. However, on discography, only 10 were judged as normal. CONCLUSIONS: On discography, thoracic discs with prominent Schmorl's nodes may be intensely painful, even in lifelong asymptomatic individuals, but the pain is unfamiliar or nonconcordant. Thoracic discography may-demonstrate disc pathology not seen on magnetic resonance imaging.

Nonoperative management of stable thoracolumbar burst fractures with early ambulation and bracing.

Eighteen neurologically intact patients with burst fractures at the thoracolumbar junction were treated with early ambulation in a total contact orthosis. No attempt was made to reduce the associated deformity. Selection criteria excluded patients with posterior column disruption. Hospital stay averaged 10 days. Follow-up averaged 19 months. Mean kyphosis was 19 at time of injury and 20 at follow-up. At follow-up, 15 patients rated their pain as little or none. Seventeen patients had little or no restriction of activity. Follow-up computed tomography (CT) scans obtained in eight patients showed significant resorption of retropulsed bone. No deterioration of neurologic function developed in any patient. In patients with intact posterior elements and thoracolumbar burst fractures, early mobilization in a total contact TLSO can lead to satisfactory functional results. Prolonged bed rest was not required in this series. The authors attribute the good results of nonoperative management to the exclusion of patients with posterior column disruption.

Biomechanical analysis of facet and graft loading in a Smith-Robinson type cervical spine model.

OBJECTIVE: This study determined the effect of change in graft height on the forces across a Smith-Robinson graft as well as across the posterior elements of the same motion segment. STUDY DESIGN: The study utilizes a strain gauge technique for the measurement of facet joint loading and a subminiature load cell for the measurement of graft loads. SUMMARY OF BACKGROUND DATA: A number of cases of Smith-Robinson procedures have had some form of collapse of the interspace and graft material after surgery. Some patients with collapse of the graft go on to have prolonged sclerotomal-type pain or pseudarthrosis. The appropriate amount of distraction is not well defined in the literature and may affect the outcome. METHODS: Cervical spines (C5-C6) were instrumented by placing strain gauges bilaterally on the pedicles of C6 (to measure the forces across the posterior elements). A miniature load cell with matching metallic shims was used to measure the force across the graft site and to distract the segment. Forces across the posterior elements and the graft site were measured, during flexion loading, and compared as the disc space was distracted. RESULTS: The ratio of posterior element load to graft load with increasing disc space distraction significantly decreased from 1.06 +/- 0.65 (1.4 mm distraction) to 0.30 +/- .13 (4.6 mm distraction) (P < .03). The posterior element load decreased significantly after the same distraction, from 46.1 +/- 22.0 to 18.7 +/- 9.7 N/Nm (P < .05). CONCLUSIONS: In spondylotic specimens (4-5 mm disc heights) disc space distraction in excess of 3.0 mm from preoperative height caused a significant decrease in both the ratio of posterior element to graft loading and posterior element loads. These findings may help explain recent clinical reports of a limit of effective disc space distraction.

The natural history of asymptomatic thoracic disc herniations.

STUDY DESIGN: Magnetic resonance imaging was used to determine the natural history of asymptomatic thoracic disc herniations. OBJECTIVES: To determine whether thoracic disc herniations change in size over time. SUMMARY OF BACKGROUND DATA: Based on previous work by the authors of the present study, the incidence of asymptomatic thoracic disc herniations is approximately 37%. The natural history of thoracic disc herniations is unknown. The natural history of lumbar and cervical disc herniations in symptomatic individuals who become asymptomatic has been shown in multiple studies frequently to result in a decrease in size of the herniation. METHODS: Twenty patients with 48 asymptomatic thoracic herniations previously diagnosed with magnetic resonance imaging underwent repeat magnetic resonance imaging using sagittal T1-weighted spine echo and axial multiplanar gradient refocused images at each thoracic disc level from T1 to T12 for a mean follow-up period of 26 months. Midsagittal canal diameter was recorded, and disc herniation square area was measured using a computer-assisted digitizing program. Disc herniations were categorized according to percentage of canal compromise. The change in size of the disc herniations over time was analyzed. RESULTS: All patients remained asymptomatic during the follow-up period. A total of 48 disc herniations were identified from the original magnetic resonance images. There were 21 small (0-10% canal compromise) disc herniations, 20 medium (> 10-20%) disc herniations, and seven large (> 20%) disc herniations. Of the 21 small disc herniations, 18 showed no significant change in size, whereas three showed a measurable increase in size. Of the 20 medium-sized disc herniations, 16 showed either a small or no change in size, one showed a significant increase in size, and three showed a significant decrease in size. Of the seven large disc herniations, three demonstrated no change in size, and four demonstrated a significant decrease in size. In addition, five new disc herniations were detected in four patients; one was small, and four were moderate in size. CONCLUSIONS: Based on the results of this study, the authors believe that asymptomatic disc herniations may well exist in a state of relative flux, yet exhibit little change in size and remain asymptomatic. There was a trend, however, for small disc herniations either to remain unchanged or increase in size and for large disc herniations often to decrease in size.

Lumbar fusion results related to diagnosis.

STUDY DESIGN: Pain outcome and functional outcome after primary lumbar fusion surgery were determined by a self-assessment questionnaire. The responses were correlated with various clinical parameters. OBJECTIVES: To determine the result of fusion surgery among patients in various diagnostic groups using semiquantitative outcome scales. SUMMARY OF BACKGROUND DATA: Most previous studies on the results of primary lumbar fusion have reported the presence of pain, but few have addressed function outcomes. Results of a literature review were inconclusive as to whether a patient's diagnosis is a predictor of improved results. METHODS: During the 3-year period from 1988 to 1990, 165 patients underwent a primary lumbar fusion procedure. They had a chart and radiograph review and were categorized into five major diagnostic groups: 1) pediatric, 2) grade I-II spondylolisthesis (low-slip), 3) grade III-IV spondylolisthesis (high-slip), 4) degenerative disc disease, and 5) postdiscectomy. At a follow-up period of 5 years (mean) after the fusion, patients were mailed a questionnaire in which they described their pain and functional status before and after their lumbar fusion surgery. Questionnaires were returned by 92% of the patients. The questionnaire scores, complications, and revision procedures were grouped by patient diagnosis and analyzed. RESULTS: Patient satisfaction with the results of primary lumbar fusion ranged from 69% (for the postdiscectomy group) to 100% (for the pediatric and high-slip groups). For all diagnostic groups, lumbar fusion resulted in a significant decrease in back pain and leg pain (visual analog scale), which was maintained throughout the follow-up period. For back pain, the pediatric and high-slip groups showed significantly more improvement than the degenerative disc disease or postdiscectomy groups. Leg pain among patients in the pediatric and high-slip groups was significantly more improved than leg pain among patients in the low-slip, degenerative disc disease, or postdiscectomy groups. There was no deterioration of pain scores during the follow-up period. After fusion, all groups had a significant decrease in Oswestry disability scores; patients in the pediatric and high-slip group had significantly more improvement than patients in the degenerative disc disease or postdiscectomy groups. High- and low-slip groups had a significant improvement in their pain drawing score. Medication use was substantially reduced in all groups. After fusion, a lack of improvement in back pain score or disability score was significantly correlated with pseudarthrosis. CONCLUSIONS: The outcome of primary lumbar fusion surgery was decreased pain and increased function for the majority of patients in all five diagnostic categories. The amount of improvement varied by diagnostic group. Patients with developmental conditions showed greater improvement than patients with degenerative conditions.

Tobacco and the institutionalized mentally retarded: usage choices and ethical considerations.

Patterns of tobacco use were observed among 749 people diagnosed with mental retardation residing in a state-operated facility. Specifically, individual preference for tobacco products and frequency of use were documented. Subjects were observed using several types of tobacco products: cigarettes, cigars, chewing tobacco, snuff, and cigarette butts. Approximately 7% (n = 52) used at least one form of tobacco; ten individuals used more than one tobacco product. Interestingly, 20.5% of the individuals diagnosed with mild or moderate mental retardation (n = 122) consumed tobacco products, a pattern of behavior that closely approximates that of the general population (20-24%). Ethical considerations pertaining to the availability of tobacco products to this special population are presented.

Pica: a peculiar behavior with oral involvement.

Pica is a behavior commonly displayed by children, pregnant females, and individuals with mental retardation. A population of institutionalized adults with mental retardation was assessed for pica. Of this population, 10.8% were identified with this behavior. Also, this article discusses aspects of pica and describes how this behavior can affect the mouth.