Tilt suppression of vestibulo-ocular reflex in patients with cerebellar lesions

The effect of tilt on the time constant of post-rotatory nystagmus was determined in a group of normal subjects and patients with cerebellar lesions. The normal subjects showed a vestibular response that decayed with a time constant of 19.6 s when upright and 7.2 s after tilt prone. Patients with midline cerebellar lesions near the uvula and nodulus had time constants that were normal in the upright position but were unaffected by head tilt. Patients with cerebellar lesions due to the Arnold-Chiari malformation showed behavior that was intermediate between that of normal subjects and the patients with midline lesions. These results provide evidence that in humans, the midline cerebellum regulates a neural network in the brainstem that perseverates peripheral vestibular input.     

Influence of eye and head position on the vestibulo-ocular reflex

Summary For the vestibulo-ocular reflex (VOR) to function properly, namely to ensure a stable retinal image under all circumstances, it should be able to take into account varying eye positions in the orbit and varying orientations of the head with respect to the axis about which it is rotating. We tested this capability by quantifying the gain and the time constant of the horizontal component of the VOR during rotation about an earth vertical axis when the line of sight (optical axis) was moved out of the plane of head rotation — either by rotating the eyes up or down in the orbit or by pitching the head up or down with respect to earth-horizontal. In either case the gain of the horizontal component of the VOR was attenuated precisely by the cosine of the angle made between the optical axis and the plane of head rotation. Furthermore, if the head was pitched up or down but the eye rotated oppositely in the orbit so as to keep the line of sight in the plane of head rotation the gain of the horizontal component of the VOR was the same value as with the head and eyes both straight ahead. In contrast, the time constant of the VOR varied only as a function of the orientation of the head and not as a function of eye position in the orbit. During rotation about an earth vertical axis, the time constant was longest (about 18 s) when the head was pitched forward to place the lateral canals near earth-horizontal and shortest (about 11 s) when the head was pitched backward to place the vertical canals near earth-horizontal. Finally, since during rotation in yaw the pattern of stimulation of the lateral and vertical semicircular canals varies with different head orientations one can use measurements of the horizontal component of the VOR, under varying degrees of pitch of the head, to calculate the relative ability of the lateral and vertical semicircular canals to transduce head velocity.Dr. Fetter is a visiting scientist from the Neurologische Universitätsklinik, Eberhard-Karls-Universität, Liebermeisterstr. 18-20, D-7400 Tübingen, Federal Republic of Germany     

Comparative genomic analysis for the presence of potential enterococcal virulence factors in the probiotic Enterococcus faecalis strain Symbioflor 1

Enterococci are members of the natural microbiota of animal and human intestinal tracts and are capable of causing opportunistic infections. They are also used as starter cultures in the food industry as well as in health supplements and probiotics by the pharmaceutical industry. This Janus-faced status requires a careful evaluation on the basis of pathogenic traits to ensure the safety of the strain used to produce food and pharmaceuticals. We performed gapped-genome sequencing of a probiotic strain Enterococcus faecalis Symbioflor 1 and present initial results deriving from comparative genome analysis with that of the previously sequenced pathogenic clinical isolate E. faecalis V583. There was strong overall conservation of synteny between both strains and a detailed analysis revealed the absence of large genomic regions from the chromosome of the probiotic strain, indicating gene loss. Genes absent from the Symbioflor 1 strain included those encoding the enterococcal cytolysin, enterococcal surface protein, and gelatinase (coccolysin) as well as hyaluronidase and the peptide antibiotic AS-48. This data was confirmed using PCR primers specific for the respective genes. However, other enterococcal determinants such as aggregation substance, collagen adhesion protein, the ability to resist oxygen anions as well as capsule formation were detected. The presence of these traits may be advantageous for the strain Symbioflor 1 since they potentially enable colonization and proliferation of the bacterium on mucosal surfaces thereby conferring on it probiotic traits.     

Effects of predictive mechanisms on head stability during forward trunk perturbation

While much is known about reflex and mechanical contributions to the control of head stability, little is known about predictive control. The goal of this experiment was to determine the contribution of predictive mechanisms to head stability in space, in the pitch plane, during forward trunk perturbations. Eleven standing healthy subjects had their trunk pulled forward by a load-pulley apparatus. The perturbation was either self-triggered or imposed (triggered by the experimenter). Subjects were exposed to two loads: 2% and 4% of their body weight. The contributions of torques acting on the head-neck system were inferred from head and trunk kinematics, neck muscle EMG, and the torques acting on the head, which were computed using inverse dynamics. The results showed that both the head and trunk moved less during the self-triggered than imposed condition during both loads for most of the participants. There was no evidence of predictive neck countertorque or increased neck muscle co-contraction during the self-triggered condition. These findings suggest that most of the subjects improved head stability in the self-triggered condition by reducing trunk motion and the associated interactive torque that perturbed the head. Electronic Publication     

Chemotherapy of non-small cell bronchial cancer with mitomycin C, vindesine and cisplatin. Results of a phase II study

Forty-five patients (39 male, 6 female) with inoperable non-small-cell lung cancer were treated with combined mitomycin C, vindesine and cisplatin. All patients had measurable disease and had no previously received chemotherapy. The performance status of all patients was over 60%. Twenty-one patients had limited, 24 extensive disease. The overall remission rate was 53.3% (3 complete and 21 partial remissions) with a median remission duration of 9 months. Adeno- and squamous cell carcinoma responded to the chemotherapy with a remission rate of 63% (7 out of 11 patients) and 58% (14 out of 24 patients), but there were only 30% responders in large cell carcinoma (3 out of 10 patients). The median survival time for responders was 12 months, for those with no change and for patients with progressive disease 6 months. Myelosuppression and renal toxicity of the combination was generally not a treatment problem; subjective tolerance, however, (gastrointestinal upset) was poor.     

A randomized, double-blind trial of nystatin therapy for the candidiasis hypersensitivity syndrome

BACKGROUND. Candida albicans infection has been proposed to cause a chronic hypersensitivity syndrome characterized by fatigue, premenstrual tension, gastrointestinal symptoms, and depression. Long-term antifungal therapy has been advocated as treatment for the syndrome, which is most often diagnosed in women with persistent or recurrent candida vaginitis. METHODS. To determine the efficacy of nystatin therapy for presumed candidiasis hypersensitivity syndrome, we conducted a 32-week randomized, double-blind, cross-over study using four different combinations of nystatin or placebo given orally or vaginally in 42 premenopausal women who met present criteria for the syndrome and had a history of candida vaginitis. The outcomes studied were the changes from base line in scores for vaginal, systemic, and overall symptoms and in the results of standardized psychological tests. RESULTS. The three active-treatment regimens (oral and vaginal nystatin, oral nystatin and vaginal placebo, and oral placebo and vaginal nystatin) and the all-placebo regimen significantly reduced both vaginal and systemic symptoms (P less than 0.001), but nystatin did not reduce the systemic symptoms significantly more than placebo. On average, the scores for systemic symptoms improved 25 percent with the three active-treatment regimens and 23 percent with the all-placebo regimen, a difference of only 2 percent (95 percent confidence interval, -3 to 7 percent). As expected, the three active-treatment regimens were more effective than placebo in relieving vaginal symptoms (P less than 0.001). All four regimens reduced psychological symptoms and global indexes of distress; there were no significant differences among the treatment regimens. CONCLUSIONS. In women with presumed candidiasis hypersensitivity syndrome, nystatin does not reduce systemic or psychological symptoms significantly more than placebo. Consequently, the empirical recommendation of long-term nystatin therapy for such women appears to be unwarranted.     

Positron emission tomography in cancer of the head and neck

The use of positron emission tomography (PET) has increased in oncology and in the assessment of head and neck tumours, where it is most useful for recurrent disease. It has good sensitivity and specificity for diagnosis and staging but is generally not necessary except in difficult cases. Quantitative measures of uptake on PET at diagnosis and after treatment do seem to have prognostic value independent of other information about the tumour and so PET may influence management. It also has a role in the identification of an unknown primary site and of synchronous primaries and metastases (often missed by other imaging). Fusion imaging with magnetic resonance (MRI) or computed tomography (CT) adds a new dimension with improved value for each technique.     

Strategies to prevent recurrence of benign paroxysmal positional vertigo

OBJECTIVE: To determine if a daily routine of Brandt-Daroff exercises increases the time to recurrence and reduces the rate of recurrence of benign paroxysmal positional vertigo (BPPV). DESIGN: Random sample of convenience and retrospective case review. SETTING: Tertiary referral center and outpatient clinic. PATIENTS: One hundred sixteen patients diagnosed with BPPV involving the posterior semicircular canal (BPPV-PC) who were successfully treated with the canalith repositioning procedure. INTERVENTIONS: Patients in the treatment group (n = 43) performed daily Brandt-Daroff exercises, while patients in the no-treatment group (n = 73) performed no exercises. MAIN OUTCOME MEASURES: Follow-up was as long as 2 years. Every 2 months patients were mailed a questionnaire. If BPPV had recurred, patients contacted the principal investigator within 24 hours. Within 1 to 2 weeks, patients were evaluated in the clinic with the Dix-Hallpike maneuver or, if unable to travel to the clinic, interviewed by telephone. RESULTS: Symptoms recurred in 50 (43%) of the 116 subjects, 34 (47%) of 73 in the no-treatment group and 16 (37%) of 43 in the treatment group. There was no significant difference in the frequency of recurrence (Pearson chi(2), P = .33) or time to recurrence (survival analysis, log-rank test, P = .92). A history of recurrent BPPV-PC did not affect frequency of recurrence (Pearson chi(2), P = .33) or time to recurrence (survival analysis, log-rank test, P = .72). CONCLUSION: Our results suggest that a daily routine of Brandt-Daroff exercises does not significantly affect the time to recurrence or the rate of recurrence of BPPV-PC.     

Delayed quick spins after vestibular nerve section respond to anticonvulsant therapy.

OBJECTIVE: To describe the clinical features of patients with failed vestibular nerve section that have a response to anticonvulsant medication. STUDY DESIGN: Retrospective case review. SETTING: Ambulatory tertiary referral center. PATIENTS: We report three patients who were afflicted with frequent brief spinning spells, or "quick spins," after vestibular neurectomy for Meniere's disease. INTERVENTION: Treatment with anticonvulsants. MAIN OUTCOME MEASURE: Relief of vertigo. RESULTS: All cases had an excellent therapeutic response to carbamazepine or oxcarbazepine, agents conventionally used for neuralgia, suggesting that these symptoms are caused by a hyperexcitable vestibular nerve. CONCLUSION: Treatment of neuralgia should be considered when the symptom of quick spins arises after vestibular neurectomy.     

Nausea and vomiting associated with cancer chemotherapy: drug management in theory and in practice

The function of cytotoxics is to damage cells, and it makes teleological sense for the body to expel them as soon after ingestion as possible. Ideally, from the body's point of view, they should simply be avoided, and it is not surprising that the experience of chemotherapy induced nausea and vomiting (CINV) is powerfully aversive. Nausea and vomiting were once among the most intractable and unpleasant experiences of a child undergoing treatment for cancer.