Rolle der Winkelstabilität bei der intramedullären Stabilisierung

Zusammenfassung Winkelstabile Plattenfixateur-interne-Systeme haben in den letzten 20 Jahren zunehmend an Bedeutung gewonnen. Die aus der Winkelstabilität resultierende flächenhafte Krafteinleitung und gleichmäßigere Kraftverteilung führen zu einer besseren Knochenbruchheilung insbesondere im metaphysischen Bereich und bei Osteoporose. Bei Marknagelsystemen ist die Winkelstabilität bislang nur partiell verwirklicht. Der vorgestellte winkelstabile Tibiamarknagel realisiert an jedem einzelnen Bolzen eine Winkelstabilität mit dem einliegenden intramedullären Kraftträger. Von Februar 2002–August 2004 wurden 21 Patienten mit ihm behandelt. In 13 Fällen wurden Frakturen stabilisiert, 6 Patienten hatten Fehlstellungen, 2 Patienten Pseudarthrosen. Zum Nachuntersuchungszeitpunkt waren alle Behandlungen abgeschlossen. Postoperative Komplikationen traten nicht auf. In allen Fällen wurde eine vollständige Durchbauung erreicht. In 6 Fällen fand sich radiologisch eine verzögerte Knochenbruchheilung. Die ersten klinischen Erfahrungen mit dem winkelstabilen Tibiamarknagel zeigen, dass dieser aufgrund der höheren Primärstabilität insbesondere im metaphysären Knochenbereich mit kurzen Fragmenten sowie bei Osteoporose Vorteile gegenüber anderen nichtwinkelstabilen oder nur partiell winkelstabilen Marknagelsystemen erbringt. Die verzögerten Knochenbruchheilungen bedürfen weiterer klinischer und biomechanischer Untersuchungen.     

5'-Nucleotidase activity increases in aging rat brain.

The enzyme 5'-nucleotidase is present in glial and neuronal membranes, and catalyzes the formation of adenosine, which in turn can act as a neuromodulator or neurotransmitter. The present study found marked increases in histochemically demonstrated 5'-nucleotidase activity in most regions of rat brain from young adulthood (3-4 months) to middle age (12-18 months), with smaller or no changes between middle and old age (24-32 months). The aging adult cerebellum showed alterations in the histochemical pattern, with declines in the molecular layer and increases in the Purkinje layer. Both myelin and synaptic plasma membrane fractions from forebrain showed increases in enzyme activity. Assays of various other body tissues suggested that the increases are fairly specific to brain, and thus apparently do not represent a ubiquitous cellular mechanism of aging. Changes in brain 5'-nucleotidase activity during aging probably reflect the increasing number and size of glial cells, and perhaps also affect synaptic transmission through regulation of adenosine.     

[I]Vasoactive intestinal peptide binding in rodent suprachiasmatic nucleus: Developmental and circadian studies

The suprachiasmatic nucleus (SCN) of rat and hamster have been studied extensively and shown to play critical roles in circadian rhythmicity. [¹²⁵I]Vasoactive intestinal peptide (VIP) binding levels are high in the rat SCN, suggesting that VIP receptors may be an important component of SCN function. In contrast to previously demonstrated diurnal variations in VIP immunoreactivity and VIP mRNA, the present study found [¹²⁵I]VIP binding to be stable across the light-dark cycle in both rat and hamster SCN. High [¹²⁵I]VIP labeling appeared to be coextensive with the rat SCN but extended somewhat beyond the cytoarchitectonic boundaries of the hamster SCN. Binding density in hamster SCN was slightly higher than in rat. In the developing rat SCN, [¹²⁵I]VIP binding levels distinguished the SCN on embryonic day 18, and appeared to increase to postnatal day 10 before declining to adult levels. The early presence of [¹²⁵I]VIP binding suggests possible involvement of VIP receptors in fetal entrainment of circadian rhythms.     

In vitro activity of ceftriaxone and other cephalosporins against 602 clinical isolates of staphylococci from geographically diverse medical centers

The in vitro activity of ceftriaxone and six additional antimicrobial agents (ceftizoxime, cefoperazone, cefuroxime, fleroxacin, ciprofloxacin, and trimethoprim/sulfamethoxazole) was assessed or 602 recent clinical isolates of staphylococci from six geographically distinct medical centers in North America. All seven antimicrobial agents were active (90–100% of strains susceptible) against oxacillin-susceptible (OS) strains of Staphylococcus aureus (OSSA) and coagulase-negative staphylococci (OSCNS) but had limited activity against oxacillin resistant (OR) staphylococci. Our assessment of the in vitro antistaphylococcal activity of ceftriaxone against contemporary isolates of Staphylococcus aureus and coagulase-negative staphylococci indicates that the activity versus OS staphylococci has not changed over the past decade despite widespread use of the drug. It appears that these agents will continue to be useful for empiric therapy in those centers in which OR strains are uncommon.Corresponding author.     

Assessment of renal artery stenosis by phase-contrast magnetic resonance angiography

Three-dimensional (3D) phase-contrast magnetic resonance angiography (MRA) and velocity-encoded cine magnetic resonance (VEC-MR) imaging were performed in 23 subjects to assess the severity of renal artery stenosis. MRA was used for detection of stenosis, demonstrating a sensitivity of 100% and a specificity of 80%; the severity of stenosis was overestimated in 33%. VEC-MR was used to quantify the renal flow oattern and was successful in 11 subjects. Mean blood flow of normal renal arteries (420 +- 107 ml/min) was significantly higher (P < 0.01) than mean blood flow of stenotic arteries (131 +- 46ml/min). The flow profile displayed both systolic and diastolic peaks in 75% of the normal arteries, while the flow in stenotic arteries showed only a single systolic peak in all cases. The systolic peak in stenotic arteries occurred significantly later (32 +- 3% of the period of one cardiac cycle) than in normal subjects (21 +- 7%) (P < 0.05). Phase-contrast MR is likely to gain considerable importance in the noninvasive aetection and quantification of renal artery stenosis. Correspondence to: C. S. Richter     

Effect of chronic vincristine treatment on mechanical withdrawal response and pre-pulse inhibition in the rat

Chemotherapeutic agents are associated with a number of serious side-effects. In addition to the development of peripheral neuropathy, patients often complain of additional symptoms related to attentional mechanisms. Although a great deal of interest is directed towards understanding the mechanisms underlying the development of peripheral neuropathy, there is a paucity of research that has examined the extent of impairment of attention in animals receiving chemotherapeutic agents. Therefore, the purpose of this experiment was to examine attentional mechanisms using the method of pre-pulse inhibition in animals that were chronically treated with vincristine. Although vincristine treated animals developed signs of peripheral neuropathy, there was no associated alteration of pre-pulse inhibition relative to vehicle treated animals. These results highlight the importance of continuing to develop methodology to model symptom burden in patients receiving chemotherapy.     

Human herpesvirus 8 infection among various population groups in southern Israel

OBJECTIVE: To compare the prevalence of antibodies to human herpesvirus 8 (HHV-8) or Kaposi sarcoma-associated herpesvirus among Israeli and Ethiopian subjects. METHODS: Serum samples were obtained from 98 Israeli Jewish students aged 18-30 years, 100 HIV-1-seronegative Ethiopian immigrants to Israel of the same age, and 100 HIV-1-seronegative Ethiopian children 1-12 years old upon their arrival in southern Israel. Plasma samples were obtained from 3 hospitalized patients with multicentric Castleman disease (MCD) as positive controls. All serum samples were tested for antibodies to both latent and lytic antigens. Antibodies to the lytic antigens and the latency-associated nuclear antigen (LANA) of HHV-8 were detected by enzyme linked immunosorbent assay and by immunofluorescence assay. HHV-8 DNA from serum or plasma samples was detected by polymerase chain reaction analysis. RESULTS: Antibodies to HHV-8 LANA were detected in 2.9% of the Israeli subjects aged 18-30 years and in 26% of the Ethiopian subjects from both age groups tested. Antibodies to the lytic antigens were detected in all 3 MCD patients, in 4% of the Ethiopian children, and in 2% of the 18- to 30-year-old Ethiopians. No antibodies to the lytic antigens were detected in the Israeli students. HHV-8 DNA was detected in all 3 MCD patients and in 2 of 4 of the Ethiopian children positive for the lytic antigens. CONCLUSIONS: HHV-8 is highly prevalent in Ethiopian immigrants to Israel as compared with Israeli students. Antibodies to HHV-8 in Ethiopia are acquired before puberty. The results of this study indicate the association of HHV-8 with MCD, as has been documented by many other researchers.     

Gaze-stabilizing deficits and latent nystagmus in monkeys with brief, early-onset visual deprivation: eye movement recordings

The normal development and the capacity to calibrate gaze-stabilizing systems may depend on normal vision during infancy. At the end of 1 yr of dark rearing, cats have gaze-stabilizing deficits similar to that of the newborn human infant including decreased monocular optokinetic nystagmus (OKN) in the nasal to temporal (N-T) direction and decreased velocity storage in the vestibuloocular reflex (VOR). The purpose of this study is to determine to what extent restricted vision during the first 2 mo of life in monkeys affects the development of gaze-stabilizing systems. The eyelids of both eyes were sutured closed in three rhesus monkeys (Macaca mulatta) at birth. Eyelids were opened at 25 days in one monkey and 40 and 55 days in the other two animals. Eye movements were recorded from each eye using scleral search coils. The VOR, OKN, and fixation were examined at 6 and 12 mo of age. We also examined ocular alignment, refraction, and visual acuity in these animals. At 1 yr of age, visual acuity ranged from 0.3 to 0.6 LogMAR (20/40-20/80). All animals showed a defect in monocular OKN in the N-T direction. The velocity-storage component of OKN (i.e., OKAN) was the most impaired. All animals had a mild reduction in VOR gain but had a normal time constant. The animals deprived for 40 and 55 days had a persistent strabismus. All animals showed a nystagmus similar to latent nystagmus (LN) in human subjects. The amount of LN and OKN defect correlated positively with the duration of deprivation. In addition, the animal deprived for 55 days demonstrated a pattern of nystagmus similar to congenital nystagmus in human subjects. We found that restricted visual input during the first 2 mo of life impairs certain gaze-stabilizing systems and causes LN in primates.     

Discharge patterns and recruitment order of identified motoneurons and internuclear neurons in the monkey abducens nucleus

1. Single neurons in the abducens nucleus were recorded extracellularly in alert rhesus macaques trained to make a variety of eye movements. An abducens neurons was identified as a motoneuron (MN) if its action potentials triggered an averaged EMG potential in the lateral rectus muscle. Abducens internuclear neurons (INNs) that project to the oculomotor nucleus were identified by collision block of spontaneous with antidromic action potentials evoked with a stimulating electrode placed in the medial rectus subdivision of the contralateral oculomotor nucleus. 2. All abducens MNs and INNs had qualitatively similar discharge patterns consisting of a burst of spikes for lateral saccades and a steady firing whose rate increased with lateral eye position in excess of a certain threshold. 3. For both MNs and INNs the firing rates associated with different, constant eye positions could be described accurately by a straight line with slope, K (the eye position sensitivity in spikes.s-1.deg-1), and intercept, T (the eye position threshold for steady firing). For different MNs, K increased as T varied from more medial to more lateral values. In contrast, the majority of INNs already were active for values of T more medial than 20 degrees and showed little evidence of recruitment according to K. 4. During horizontal sinusoidal smooth-pursuit eye movements, both MNs and INNs exhibited a sinusoidal modulation in firing rate whose peak preceded eye position. From these firing rate patterns, the component of firing rate related to eye velocity, R (the eye velocity sensitivity in spikes.s-1.deg-1.s-1), was determined. The R for INNs was, on average, 78% larger than that for MNs. Furthermore, R increased with T for MNs, whereas INNs showed no evidence of recruitment according to R. If, as in the cat, the INNs of monkeys provide the major input to medial rectus MNs and if simian medial rectus MNs behave like our abducens MNs, then recruitment order, which is absent in INNs, must be established at the MN pool itself. 5. Unexpectedly, the R of MNs decreased with the frequency of the smooth-pursuit movement. Furthermore, the eye position sensitivity, K, obtained during steady fixations was usually less than that determined during smooth pursuit. Therefore, conclusions about the roles of MNs and premotor neurons based on how their R and K values differ must be viewed with caution if the data have been obtained under different tracking conditions.(ABSTRACT TRUNCATED AT 400 WORDS)     

Fastigial nucleus activity in the alert monkey during slow eye and head movements

1. Single units were recorded extracellularly from the fastigial nucleus of three macaque monkeys. Two untrained animals were subjected to whole-body yaw rotations in the light and dark and to full-field horizontal optokinetic stimuli provided by a drum with vertical stripes. The third also was subjected to sinusoidal yaw rotations but, in addition, was trained to follow a small spot, which moved in various ways relative to the animal, to reveal possible smooth pursuit and vestibular sensitivities. 2. On the basis of their responses to vestibular and optokinetic stimuli and their responses during smooth pursuit, fastigial neurons could be divided functionally into a rostral and a caudal group. 3. Most rostral neurons exhibited an increased firing for contralateral head rotations and ipsilateral optokinetic stimuli. A few had the opposite combination of directional preferences. The average firing rates increased monotonically both with contralateral head velocity and ipsilateral drum velocity and decreased monotonically for the oppositely directed movements. There was no change in firing rate for either spontaneous saccades or smooth pursuit of a small moving spot. 4. In contrast, neurons in the caudal fastigial nuclei not only have a robust vestibular sensitivity, but respond during smooth pursuit as well. Most discharge during contralateral head velocity and contralateral smooth pursuit so that they exhibit very little modulation during the vestibuloocular reflex (VOR) or when the rotating animal is fixating a target stationary in the world (SIW). The remaining neurons discharge during contralateral head rotations but ipsilateral eye rotations; these units exhibit their greatest modulation during the SIW condition. 5. Because they respond during quite different behavioral situations, it seems likely that rostral fastigial neurons are involved with descending control of the somatic musculature, whereas the caudal neurons are involved in oculomotor control. The sparse anatomic and lesion data that is available is consistent with this idea.