Hyperactive vestibulo-ocular reflex in cerebellar degeneration: pathogenesis and treatment

We studied a patient with a cerebellar degeneration and hyperactive vestibulo-ocular reflex (VOR). He complained of oscillopsia and blurred vision with head movement. A twofold increase in VOR gain (peak eye velocity/peak head velocity) at high frequencies was associated with a VOR time constant of 6 seconds (low normal). Visual cancellation ("suppression") of the VOR and smooth pursuit were also abnormal. We hypothesized that his high VOR gain was due to dysfunction of olivocerebellar projections. Physostigmine reduced his VOR gain, consistent with the hypothesis that these projections are cholinergic.     

Clinical and ocular motor analysis of congenital nystagmus in infancy.

PURPOSE: The purpose of this study was to identify the clinical and ocular motility characteristics of congenital nystagmus and to establish the range of waveforms present in infancy. BACKGROUND: The clinical condition of congenital nystagmus usually begins in infancy and may or may not be associated with visual sensory system abnormalities. Little is known about its specific waveforms in infancy or their relationship to the developing visual system. METHODS: Forty-three infants with involuntary ocular oscillations typical of congenital nystagmus were included in this analysis. They were evaluated both clinically and with motility recordings. Eye movement analysis was performed off line from both chart recordings and computer analysis of digitized data. Variables analyzed included age, sex, vision, ocular abnormalities, head position, null-zone or neutral-zone characteristics, symmetry, conjugacy, waveforms, frequencies, foveation times, and responses to convergence and to monocular cover. RESULTS: Patient ages ranged from 3 to 18 months (average, 9.2 months). Seventeen patients (40%) had abnormal vision, 3 had a positive family history of nystagmus, 11 had strabismus, 16 (37%) had a head posture, 26 (60%) had null and neutral positions, 14 (33%) had binocular asymmetry, and all were horizontally conjugate. Average binocular frequency was 2.8 Hz, and average monocular frequency was 4.6 Hz. The waveforms were both jerk and pendular; average foveation periods in patients with normal vision were more than twice as long as those in patients with abnormal vision. CONCLUSIONS: Common clinical characteristics and eye-movement waveforms of congenital nystagmus begin in infancy, and waveform analysis at this time helps with both diagnosis and visual status.     

Variable waveforms in downbeat nystagmus imply short-term gain changes

A patient with downbeat nystagmus subsequent to ankylosing spondylitis was studied. His nystagmus was found to exhibit both increasing- and decreasing-velocity exponential slow phases as well as the linear form more often reported. Alternation between waveforms sometimes occurred on a beat-to-beat or even intrabeat basis. Possible explanations for all three waveforms are presented in terms of short-term gain changes in cerebellar compensation for leaky brainstem neural integrators. A computer model was developed and its results are discussed.     

Paroxetine in Parkinson's disease: effects on motor and depressive symptoms

Selective serotonin reuptake inhibitors have been used in the treatment of depression in patients with PD. Conflicting data as to whether selective serotonin reuptake inhibitors worsen parkinsonian motor symptomatology have been reported. In this study, the additional 6 months therapy with paroxetine 20 mg/d in a group of depressed patients with PD did not modify parkinsonian motor function (Unified Parkinson's Disease Rating Scale scores); however, in one patient, fully reversible worsening of tremor was observed. Depression, as evaluated by Beck Depression Inventory and Hamilton Depression Rating Scale, improved from baseline to final visit (p < 0.05 by analysis of variance).     

Expression of fibrinogen receptors during activation and subsequent desensitization of human platelets by epinephrine

Epinephrine causes platelet aggregation and secretion by interacting with alpha 2-adrenergic receptors on the platelet surface. Platelet aggregation requires the binding of fibrinogen to a specific receptor on the membrane glycoprotein IIb-IIIa complex. Although the IIb-IIIa complex is identifiable on the surface of resting platelets, the fibrinogen receptor is expressed only after platelet activation. The current studies were designed to examine the effect of occupancy of platelet alpha 2-adrenergic receptors by epinephrine on the expression of fibrinogen receptors and on the aggregation of platelets. The ability of epinephrine to induce the expression of fibrinogen receptors was studied under two different conditions: acute stimulation (less than 1 min) and prolonged stimulation (50 to 90 min), the latter of which is associated with a reduction or "desensitization" of the platelet aggregation response. Expression of the fibrinogen receptor was monitored with 125I-fibrinogen as well as with 125I-PAC-1 (PAC-1), a monoclonal antibody that binds to the glycoprotein IIb-IIIa complex only after platelets are activated. Epinephrine caused an immediate increase in PAC-1 and fibrinogen binding that was dependent on occupancy of the alpha 2-receptor by epinephrine and on the presence of extracellular free Ca (KCa = 30 mumol/L). By itself, 1 mmol/L Mg was unable to support induction of the fibrinogen receptor by epinephrine. However, it did decrease the Ca requirement by about two orders of magnitude. Prolonged stimulation of unstirred platelets by epinephrine led to a 70% decrease in the aggregation response when the platelets were subsequently stirred. Despite their decreased aggregation response, desensitized platelets bound PAC-1 and fibrinogen normally, indicating that the loss of aggregation was not due simply to a decrease in fibrinogen receptor expression. Although desensitization was not affected by pretreatment of the platelets with aspirin, it was partially prevented when extracellular Ca was chelated by EDTA during the long incubation with epinephrine. These studies demonstrate that once platelet alpha 2-adrenergic receptors are occupied by epinephrine, extracellular Ca is involved in initiating the aggregation response by supporting the induction of the fibrinogen receptor and the binding of fibrinogen. Furthermore. Ca-dependent reactions subsequent to fibrinogen binding may be necessary for maximal platelet aggregation and are impaired when platelets become desensitized to epinephrine.     

Chlorambucil therapy in hairy cell leukemia: effects on lipid composition and lymphocyte subpopulations

Two patients with progressive hairy cell leukemia following splenectomy were treated with low-dose daily chlorambucil. Both had an objective hematologic response as determined by a return to normal hematocrit and platelet count. This was also reflected in the mononuclear cell fraction by the normalization of cholesterol content, cholesterol/phospholipid ratio, and the lymphocyte subpopulations. This article confirms previous reports on the efficacy of chlorambucil in this setting and describes some morphological, and biochemical concomitant events.     

Trastuzumab-induced cardiotoxicity in elderly women with HER-2-positive breast cancer: a meta-analysis of real-world data

Background: We conducted a meta-analysis to assess the overall risk of cardiac toxicity associated with trastuzumab treatment in elderly breast cancer patients.

Methods: We searched databases from PubMed, EMBASE and Cochrane Central Registry of Controlled Trials to identify relevant studies. Statistical analyses were conducted to calculate the incidence rate, overall hazard ratio (HR) and 95% CIs using a fixed effects model.

Results: A total of 116,342 and 360 elderly patients from five cohort studies and two randomized clinical trials (RCTs) were included for analysis. The pooled incidences of symptomatic congestive heart failure (CHF) and CHF/HF/CM were 6.4% (95% CI 4.1% – 9.4) and 16.4% (95% CI 16.19% – 16.61) in patients with median age of 67.5 years from two RCTs and in patients with median age of 67.5 (60 – 75), 71 (66 – 80+), 74.5 (65 – 89), 75 (66 – 81+) and 79.5 (60 – 99) from five cohort studies, respectively. Trastuzumab was significantly correlated with an increased risk of defined cardiac toxicities in five cohort studies (HR = 1.89, 95% CI 1.72 – 2.07, p < 0.00001) and two RCTs (HR = 3.00, 95% CI 1.71, 5.26, p < 0.00001). Sub-group analysis showed that the anthracycline-based chemotherapy increased the risk of CHF/HF and CM in patients among five cohort studies (HR = 2.16, 95% CI: 1.8 – 1.87, p < 0.00001).

Conclusion: Trastuzumab is likely associated with an increased risk of cardiac toxicity in elderly patients with HER-2-positive breast cancer. Carefully monitoring cardiac function in elderly patients receiving trastuzumab, particularly with concurrent use of anthracycline, is warranted.