Predictive control of muscle responses to arm perturbations in cerebellar patients

OBJECTIVES: To examine changes in predictive control of early antagonist responses to limb perturbations in patients with defined lesions of the cerebellum. METHODS: Eight cerebellar patients and eight sex and age matched control subjects participated. Subjects held a handle that was rotated around the elbow joint. They were instructed to hold the forearm at 90 degrees flexion against a mechanical perturbation. Extensor torque (5 Nm) was applied for 140 ms (pulse), or for 1400 ms (step) through an external motor. Motor responses were tested under two different conditions of anticipatory information. In the expected condition, subjects anticipated and received a pulse. Under the unexpected condition, subjects expected steps, but received unexpected pulses. Biceps and triceps EMG as well as angular kinematics were compared between expected and unexpected pulse perturbations to quantify possible effects of prediction. RESULTS: In all healthy subjects, the degree of overshoot in the return flexion movement was significantly less in expected pulse perturbations compared with unexpected trials. The degree of amplitude reduction was significantly smaller in the patient group than in the control group (22.8% v 40.0%). During the expected trials, latency of peak triceps activity was on average 20% shorter in the control group, but 4% larger in the cerebellar patients. CONCLUSIONS: In the expected condition, controls achieved a significant reduction in angular amplitude by generating triceps activity earlier, whereas the ability to use prediction for adjusting early antagonist responses after limb perturbation was impaired in cerebellar patients.     

Neuroanatomical correlates of the near response: voluntary modulation of accommodation/vergence in the human visual system

This study identifies brain regions participating in the execution of eye movements for voluntary positive accommodation (VPA) during open-loop vergence conditions. Neuronal activity was estimated by measurement of changes in regional cerebral blood flow (rCBF) with positron emission tomography and 15O-water. Thirteen naive volunteers viewed a checkerboard pattern with their dominant right eye, while a lens interrupted the line of gaze during alternate 1.5 s intervals. Three counterbalanced tasks required central fixation and viewing of a stationary checkerboard pattern: (i) through a 0.0 diopter (D) lens; (ii) through a -5.0-D lens while avoiding volitional accommodation and permitting blur; and (iii) through a -5. 0-D lens while maintaining maximal focus. The latter required large-amplitude, high-frequency VPA. As an additional control, seven of the subjects viewed passively a digitally blurred checkerboard through a 0.0-D lens as above. Optometric measurements confirmed normal visual acuity and ability to perform the focusing task (VPA). Large-amplitude saccadic eye movements, verified absent by electro-oculography, were inhibited by central fixation. Image averaging across subjects demonstrated multifocal changes in rCBF during VPA: striate and extrastriate visual cortices; superior temporal cortices; and cerebellar cortex and vermis. Decreases in rCBF occurred in the lateral intraparietal area, prefrontal and frontal and/or supplementary eye fields. Analysis of regions of interest in the visual cortex showed systematic and appropriate task dependence of rCBF. Activations may reflect sensorimotor processing along the reflex arc of the accommodation system, while deactivations may indicate inhibition of systems participating in visual search.     

Put more "bite" into health promotion: a campaign to revitalize health promotion in the Army Dental Care System. Part I. The mouthguard, sealant, and nursing caries initiatives

During the course of 1998, the Army Dental Care System launched "Put More 'Bite' into Health Promotion," a campaign to revitalize health promotion in the Army Dental Care System. In this paper, we discuss the content, rationale, and evidence base for three of five health promotion initiatives that are part of the campaign: mouthguard fabrication and counseling, sealant placement and education, and nursing caries education.     

Proliferative activity in primary ovarian carcinoid tumors.

The proliferative potential of six primary ovarian carcinoids with different clinical outcome and histogenetic origin was examined immunohistochemically. The results showed that two cases with extremely high level of proliferative activity were associated with metastatic spread. In the remaining tumors, the examined factor was found to be at low level comparable with excellent prognosis of typical carcinoids in other locations. The preliminary results showed a possibility of a prognosis prediction according to typing of the ovarian carcinoids into two categories, i.e., tumors of low and intermediate malignancy. Topoisomerase II-alpha and Ki-67 are suitable markers giving valuable information about this phenomenon.     

Serious adverse effects of amifostine during radiotherapy in head and neck cancer patients

Background and purpose: Amifostine has been shown to protect against xerostomia induced by radiotherapy for head and neck cancer, but its impact on the therapeutic index is unknown. This is the first report focusing on amifostine related adverse effects leading to discontinuation of amifostine treatment.

Patients and methods: Thirty-nine patients from two centers irradiated for head and neck cancer received i.v.-infusions of amifostine prior to each radiation fraction. In a phase III study, two daily amifostine doses, 200 mg/m² (n=21) and 340 mg/m² (n=18), were compared for protection against radiation induced toxicity. Total radiation dose was 60–70 Gy (2 Gy per fraction), nine patients received concurrent chemotherapy with cisplatin/5-FU. amifostine was usually discontinued after >1 episode of serious toxicity during subsequent treatment sessions.

Results: In 16/39 patients (41%) amifostine was discontinued due to severe adverse effects, which led to discontinuation of the phase III study. In four of 16 patients radiotherapy was delayed due to amifostine related adverse effects for 1–3 days. Discontinuation occurred more often in patients receiving chemotherapy. The results led to a literature review for amifostine treatment during radiotherapy in head and neck cancer patients. Regarding our series and published series using an amifostine schedule comparable to ours, total discontinuation rate was 27% (57/214). Discontinuation was significantly influenced by chemotherapy (P=0.007), but not by amifostine dose (P=0.156).

Conclusion: Daily i.v. administration of amifostine during radiotherapy in head and neck cancer is associated with a high rate of serious adverse effects leading to discontinuation of amifostine treatment and sometimes delay of radiotherapy.     

Effect of warm ischemia time and organ perfusion technique on liver microvascular preservation in a non-heart-beating rat model

BACKGROUND: Current organ shortage has led to a reconsideration of non-heart-beating cadaveric donation. METHODS: We assessed the effectivity of dual, i.e., arterial and portal-venous versus exclusive, arterial gravity perfusion for procurement of rat livers after 30 min and 60 min of cardiac arrest, analyzing the rate and homogeneity of microvascular perfusion by in situ fluorescence microscopy. RESULTS: After 30 min of cardiac arrest, a nearly 100% recovery of acinar perfusion with a sinusoidal density not significantly different from that of normal, nonischemic livers was achieved by dual gravity perfusion. Prolongation of cardiac arrest to 60 min caused an almost 50% deficit of acinar and sinusoidal perfusion (P<0.05) with a concomitant 2-3-fold increase of heterogeneity of hepatic microperfusion. Regardless of the warm ischemic time period, dually perfused livers exhibited significantly (P<0.05) higher rates of both acinar and sinusoidal perfusion with increased homogeneity of microcirculation when compared with exclusive arterial perfusion. CONCLUSION: These data underline the need and benefit of dual perfusion as well as the limitation of warm ischemic tolerance to 30 min for safe liver procurement of non-heart-beating donors.     

The nature of the myenteric infiltrate in achalasia: an immunohistochemical analysis

Achalasia is an esophageal motor disorder characterized by abnormal relaxation of the lower esophageal sphincter and absence of progressive peristalsis in the esophageal body. Previous studies evaluating esophagomyotomy and esophageal resection specimens have shown the presence of myenteric inflammation to be a consistent and early pathologic change in patients with achalasia. Thus, the goal of this study was to determine the immunohistochemical characteristics of the inflammatory infiltrate within the myenteric plexus in patients with clinically early and end-stage achalasia. Using formalin-fixed tissue, we analyzed the immunohistochemical features of the myenteric lymphocytes using antibodies that recognize B cells (CD20), T cells (CD3), T cell subsets (CD8), and the activation state of T cell subpopulations (TIA-1 and granzyme B) in nine patients with clinically early achalasia who underwent esophagomyotomy and 13 patients with clinically endstage achalasia who underwent esophageal resection. The myenteric infiltrate in all nine esophagomyotomy specimens was composed predominantly of T cells (CD3-positive), the majority of which also stained for CD8. In five of nine specimens, the majority of CD8-positive cells stained for TIA-1. In the esophageal resection specimens, the myenteric infiltrate was composed predominantly of CD3-positive T cells in seven of 13 cases. In three cases, there was a predominance of CD20-positive B cells, and in the remaining three cases there were relatively equal numbers of T and B cells. In eight of 13 cases, the majority of T cells stained for CD8. TIA-1 immunoreactivity was found in the majority of CD8-positive cells in nine of 13 cases. In all esophagomyotomy and esophageal resection specimens studied, rare granzyme B-positive cells were detected. In conclusion, the majority of myenteric inflammatory cells in patients with achalasia are CD3-positive T cells, most of which are also CD8-positive, although the relative percentage of such cells appears to decrease with disease progression. Furthermore, many of the CD3-positive/CD8-positive myenteric lymphocytes also express TIA-1, suggesting they are resting or activated cytotoxic T cells. The immunohistochemical demonstration of granzyme B in a subpopulation of these cells supports the contention that achalasia is an immune-mediated disease, although the inciting antigen remains an enigma.     

Operative Behandlung von geburtstraumatischen Läsionen des Plexus brachialis

Zusammenfassung Fragestellung: Geburtstraumatische L?sionen des Plexus brachialis treten in 0,6–2,5‰ aller Geburten auf. 80–95% dieser L?sionen bilden sich spontan zurück. Sollte keine spontane Funktionsrückkehr innerhalb der ersten 6 Monate eintreten, mü?te nach entsprechender Diagnostik, wie elektrophysiologische und myelocomputertomographische Untersuchungen eine operative Freilegung des Plexus brachialis erfolgen. Methode: In einem Zeitraum von 5 Jahren haben wir 7 Kinder mit postpartaler Plexusl?sion unter 99 operativ versorgten Plexusl?sionen behandelt. 6/7 Kindern zeigten pr?operativ Wurzelausrisse. Bei 2 Kindern wurde eine Neurotisation, bei 4 eine autologe Transplantation und beim letzten eine ?u?ere Neurolyse des Plexus brachialis vorgenommen. Ergebnisse: Bisher wurden nur 3/7 Kindern über einen l?ngeren Zeitraum (26–42 Monate) nachuntersucht. Alle transplantierten Nerven zeigten klinisch eine Reinnervation. Eine Wiederherstellung der normalen Funktion war durch begleitende Wurzelausrisse limitiert. Schlu?folgerungen: Wir empfehlen als optimalen Zeitpunkt für die Operation den Zeitraum zwischen dem 6. und 9. Monat. Um optimale Ergebnisse bei diesen Kindern zu erzielen, mu? sich zun?chst eine intensive krankengymnastische Behandlung anschlie?en und sp?ter sollte die Option für Muskeltransfers und orthop?dische Operationen gew?hrleistet sein.