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D Dressler

Publications and source records attributed to D Dressler.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Botulinum toxin--the dose controls the poison. A historical sketch].

Botulism, a potentially lethal form of paralytic food poisoning, was described as early as 1793. Basic research, especially in the late nineteenth and early twentieth centuries, revealed that botulism is caused by exotoxins. Further biochemical work around and after the Second World War gave insight into the molecular structure of seven different serotypes of botulinum toxin (BT/A-G) as well as into its acetylcholine blocking mode of action. In 1977, Scott treated patients with strabism by injecting minute amounts of purified BT/A. In short sequence, BT proved effective in blepharospasm, cervical dystonia, and various off-label indications. In the near future, registration of these new indications, marketing of new serotypes (BT/B), and availability of more practical antibody tests can be expected. The first applications of BT were performed by Roggenkaemper, Dressler, and Benecke in Germany and by Poewe and Auff in Austria. According to a worldwide trend, a rapid expansion regarding BT users and indications followed. Formation of BT competence centers in both countries aims at maintaining high standards in BT research and education.

Austria↗
PubMed2002

Substantia nigra echogenicity is normal in non-extrapyramidal cerebral disorders but increased in Parkinson's disease.

Transcranial sonography (TCS) revealed substantia nigra (SN) hyperechogenicity in idiopathic Parkinson's disease (IPD). To further evaluate specificity of this finding, we examined 30 IPD patients and 30 age-matched subjects with non-extrapyramidal cerebral disorders (NED). All IPD patients showed a SN hyperechogenicity, in 17 it was bilateral and in 13 unilateral. 7 NED patients had a SN hyperechogenicity, in all it was unilateral, confirming previous results in healthy subjects. Bilateral SN hyperechogenicity indicates IPD and normal SN echogenicity indicates NED. In 30% of patients TCS does not distinguish between IPD and NED. Data further support the assumption that bilateral SN hyperechogenicity is specific for IPD.

Aged↗
PubMed2001

Improvement in quality of life outcomes 2 weeks after left ventricular assist device implantation.

BACKGROUND: The successful use of left ventricular assist devices (LVADs) as a bridge to heart transplantation has prompted our examination of quality of life (QOL) outcomes. The purposes of this study are to describe QOL in patients 1 to 2 weeks after LVAD implantation and to compare QOL in a smaller cohort of patients from before to 1 to 2 weeks after surgery. METHODS: Data were collected from a convenience sample of 81 patients who completed booklets of questionnaires that measure domains of QOL 1 to 2 weeks after LVAD insertion and from 30 of 81 patients who completed booklets at both the pre-implantation and post-implantation periods. Patients completed booklets of 6 to 8 self-reporting instruments, with acceptable reliability and validity. Data were analyzed using descriptive and comparative statistics (chi-square, Mann-Whitney U and Wilcoxon signed ranks tests) with p = 0.01 considered statistically significant. RESULTS: One to 2 weeks after LVAD implantation, patients were quite satisfied with their lives, experienced moderately low amounts of stress, coped well, and perceived themselves as having good health and QOL, low symptom distress, and moderately low functional disability. Patients reported significantly better QOL, more satisfaction with health and functioning, and were significantly less distressed by symptoms from immediately pre-operatively to post-operatively. However, patients reported significantly more self-care disability and more dissatisfaction with socioeconomic areas of life from before to immediately after surgery. Psychological distress was low and did not change with time. CONCLUSION: Given that QOL improved from before to after LVAD implantation, our findings provide a springboard for investigation of the impact of LVADs on long-term QOL outcomes.

Adult↗
PubMed2001

The pharmacokinetics and metabolic disposition of tacrolimus: a comparison across ethnic groups.

OBJECTIVE: Our objective was to compare the intravenous and oral pharmacokinetics of tacrolimus among subjects of three different ethnic backgrounds, African American, white, and Latin American. METHODS: Ten African American, 12 white, and 12 Latin American subjects received intravenous and oral tacrolimus in an open-label, two-period, parallel group study. All of the subjects received intravenous tacrolimus (0.015 mg/kg) as a constant infusion over 4 hours and oral tacrolimus capsules (5 mg) as single doses in randomized order. Concentrations of tacrolimus and its metabolites were measured in whole blood with the use of a validated HPLC-mass spectrometry assay. RESULTS: There were no significant differences in pharmacokinetic parameters among the three study groups after intravenous administration of the drugs. After oral administration, the tacrolimus maximum concentration was significantly lower (P < .01) in the African American subjects (20.8 microg/L) than in the white subjects (37.8 microg/L) and Latin American subjects (33.0 microg/L). Absolute bioavailability was significantly lower (P = .01) in the African American subjects (11.9%) and in the Latin American subjects (14.4%) than in the white subjects (18.8%). After the oral dose, the area under the plasma concentration-time curve was lower in the African American subjects (179 microg/L x h, geometric mean) than in the white (293 microg/L x h) and Latin American subjects (239 microg/L x h, differences not statistically significant). Maximum concentration (P < .02) and area under the plasma concentration-time curve (not statistically significant) of the main tacrolimus metabolite 13-O-desmethyl tacrolimus was lower in the African American subjects than in the white and Latin American subjects. CONCLUSIONS: Significant differences in tacrolimus pharmacokinetics exist among the three different ethnic groups. Our results indicate that this may result from differences in intestinal CYP3A or P-glycoprotein activities.

Adult↗
PubMed2001

Abnormal interaction between vestibular and voluntary head control in patients with spasmodic torticollis.

The functional status of vestibulo-collic reflexes in the sternocleidomastoid (SCM) muscles was investigated in 24 patients with spasmodic torticollis using small, abrupt 'drops' of the head. None had been treated with botulinum toxin injections during at least 4 months preceding the study. Eight of the patients, four of whom had been studied before surgery, were also studied after selective peripheral denervation of neck muscles. The reflex was of normal latency and duration in the 'passive drop' condition, in which subjects were instructed not to oppose the fall of the head. To study voluntary interaction with the reflex response, subjects were then asked to flex the neck as quickly as possible after onset of the head drop ('active drop'). In this condition, voluntary responses in patients were delayed, smaller and less effective in counteracting the head fall than in normal subjects. The same abnormalities were also found in patients after surgery when the head posture was improved. Somatosensory/auditory voluntary reaction times in SCM were normal, as was the latency of the startle reflex. We conclude that voluntary interaction with the vestibulo-collic reflex is disrupted in patients with spasmodic torticollis, a finding which corroborates the patients' aggravation of their symptoms by head or body perturbations. Lack of effective interaction between two major systems controlling head position may contribute to torticollis.

Adult↗
PubMed2001

Prospective study of selective peripheral denervation for botulinum-toxin resistant patients with cervical dystonia.

We have carried out a prospective study of selective peripheral denervation (SPD) in cervical dystonia (CD) patients with primary or secondary botulinum toxin (BT) treatment failure using independent standardized assessment. Patients referred for surgery had a standardized clinical examination, neck muscle EMG, videofluoroscopic swallow and CT of the cervical spine, and were selected for surgery on the basis of the results of these investigations. CD severity, disability and pain were assessed preoperatively and at 3, 6, 9, 12 and 18 months postoperatively using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Severity of head tremor and dysphagia were scored using established rating scales. Additionally, psychosocial function was assessed in a representative subsample of patients (n = 12) using several established questionnaires. Of the 62 patients who were assessed, 22 (35.5%) were not offered surgery, most commonly because of widespread dystonia. Of the remaining 40 patients, 37 have so far had surgery, 31 of whom have been followed up for at least 1 year, and 15 for 18 months after surgery (mean follow-up duration 16.7 months). Using the TWSTRS global outcome score, 68% of patients derived functionally relevant improvement at 12 months after surgery. In the entire operated group, total TWSTRS scores were reduced by 30% at 6 and 12 months after surgery (P < 0.0001). The subscores for severity, disability and pain were reduced by 20, 30 and 40%, respectively, at 6 months (P < or = 0.01) and 20, 40 and 30%, respectively, at 12 months (P < 0.01). Pain increased over time, which appeared to result from muscle reinnervation. TWSTRS scores were not significantly improved in the six patients with primary BT treatment failure. Head tremor did not change. There was a significant improvement of body concept, perceived disfigurement, stigma, and quality of life in the 12 patients whose psychosocial function was assessed. Preoperative disability and restriction of head movement were negatively correlated and the initial response to BT treatment positively correlated with global outcome score. Spread or deterioration of dystonia elsewhere in the body occurred in three patients, with unpleasant sensory symptoms in denervated posterior cervical segments occurring in 14. Ten patients developed mild to moderate dysphagia, and two developed severe dysphagia. We conclude that SPD is an effective treatment for patients with secondary, but probably not for those with primary, BT treatment failure. Reinnervation is not infrequent and can compromise outcome. Postoperative morbidity is low, but there is a risk of dysphagia.

Botulinum Toxins↗
PubMed2001

Quantitation of free and total amphotericin B in human biologic matrices by a liquid chromatography tandem mass spectrometric method.

Amphotericin B remains the standard of care for the treatment of invasive and disseminated fungal infections. Various lipid-based formulations of amphotericin B have been developed to improve its therapeutic index by decreasing toxicity. Previous bioanalytic methods using microbial inhibition or high-pressure liquid chromatography quantified total amphotericin B (free, plasma protein-bound, and lipid-complexed). Sensitivity of this method with a low limit of quantitation of 0.05 microg/mL was inadequate to determine free (unbound) amphotericin B. A sensitive LC/MS/MS method was developed to determine the total amphotericin B value in human plasma and other biologic matrices and the free amphotericin B concentration in plasma. For determination of total plasma amphotericin B concentrations, the sample was diluted and injected onto the LC/MS/MS. For total amphotericin B in other matrices and free amphotericin B in plasma, solid-phase extraction was used. Natamycin served as an internal standard. A PE Sciex API 3000 (Sciex; Concord, Ontario, Canada) was used to assess free amphotericin B in plasma ultrafiltrate determination and an API 3+ for the other matrices, with electrospray interfaced to a C18 analytic column. The low limit of quantitation was 1 ng/mL for ultrafiltrate. For total amphotericin B, the low limits were 2 microg/mL for plasma, 0.05 microg/mL for urine, and 0.4 microg/mL for fecal homogenate. The methods were validated to show the standard range linearity, sensitivity, selectivity, accuracy, precision, and stability of amphotericin B in the matrices tested.

Amphotericin B↗
PubMed2001

Botulinum toxin antibody testing: comparison between the immunoprecipitation assay and the mouse diaphragm assay.

Antibodies against botulinum toxin (BT) are currently best detected by the mouse diaphragm assay (MDA). Nevertheless, the MDA still has disadvantages, so that an immunoprecipitation assay (IPA) was introduced recently. We sought to compare the results of both tests. 33 samples from patients with cervical dystonia and complete or partial BT therapy failure underwent blinded simultaneous IPA and MDA testing. 27 (82%) samples showed concordant results, 17 (52%) being positive and 10 (30%) negative for both IPA and MDA resulting in a significant association of the dichotomous test results (Fisher's exact test, p < 0.01). The other six samples (18%) showed discordant results, all being IPA-negative and MDA-positive. This excess of MDA-positive results was also significant (Sign rank test, p = 0.03). IPA and MDA results showed a very strong and significant qualitative and quantitative association. The IPA seems to be less sensitive than the MDA for detection of low BT-AB titres, but the clinical relevance of this still needs to be established. Since the IPA is simpler, faster and cheaper than the MDA and avoids sacrifice of animals, it could become the preferred BT-AB test.

Animals↗
PubMed2001

Effect of low- and high-fat meals on tacrolimus absorption following 5 mg single oral doses to healthy human subjects.

Tacrolimus (FK506, Prograf) is a macrolide lactone antibiotic widely used by the oral route for the prophylaxis of organ rejection in patients who have received allogenic liver or kidney transplants. This study investigated the influence of a high- versus a low-fat meal, relative to the fasting state (three treatments total), on the rate and extent of tacrolimus absorption following a single 5 mg oral dose. The protocol employed a three-period, randomized, crossover design employing 5 x 1 mg capsules in 15 healthy male nonsmoking, drug-free volunteers, 20 to 45 years of age, who were within 15% of their ideal body weight. Food had a clinically significant effect in reducing relative bioavailability, as well as slowing absorption, but did not affect terminal exponential half-life (approximately 34 hours). Mean maximum tacrolimus blood concentration (Cmax) values were 25.6, 5.88, and 9.03 ng/mL for the fasting, high-fat, and low-fat treatments, respectively; mean area under the blood concentration-time curve (AUC(0-infinity) values were 272, 181, and 201 (ng/mL)-h, respectively; and mean time of Cmax (tmax) values were 1.37, 6.47, and 3.20 hours, respectively. Differences in parameters between the fasting and each fed treatment were statistically significantly different (p < 0.05). Statistically significant differences also existed in tmax between the two meals. Results also indicated the safety of single 5 mg oral tacrolimus doses administered to healthy volunteers.

Administration, Oral↗
PubMed2001

Effect of time of meal consumption on bioavailability of a single oral 5 mg tacrolimus dose.

Tacrolimus (FK506, Prograf) is marketed for the prophylaxis of organ rejection following allogenic liver or kidney transplantation. This study investigated the effect of timing of a standardized breakfast meal on both the rate and extent of tacrolimus absorption following a single 5 mg oral dose. The protocol used a randomized, open-label, four-period, four-treatment, four-sequence crossover design in 16 healthy, nonsmoking, drug-free male subjects between the ages of 22 and 45 years who were within 15% of their ideal body weight. The four treatments were the following: (A) fasting for 10 hours, (B) ingestion 1 hour before breakfast, (C) ingestion immediately following consumption of the breakfast, and (D) ingestion 1.5 hours after beginning consumption of the breakfast. The breakfast, which was consumed over 15 minutes, contained 848 kcal, with 30%, 16%, and 54% of calories derived from fat, protein, and carbohydrate, respectively. Tacrolimus absorption in the fasting state provided the greatest relative bioavailability (p < 0.05 compared with all other three treatments). AUC(0-infinity)) averaged 312, 276, 205, and 203 ng x h/mL for treatments A, B, C and D, respectively. In contradistinction to taking the drug 1 hour prior to a meal, which had a relatively minor impact on the relative extent of absorption (approximately 12%) compared to the fasting state, ingestion of tacrolimus immediately after a meal (treatment C) or 1.5 hours subsequent to a meal (treatment D) had a more pronounced influence. Mean AUC(0-infinity) ratios (fasting to either postmeal treatments) were approximately 1.5, indicating that absorption extent was considerably reduced by ingesting tacrolimus capsules immediately after eating or 1.5 hours thereafter. Absorption was also prolonged following drug ingestion after a meal, as indicated by a mean tmax value in the fasting state of 1.84 hours, relative to 3.41 hours (immediately aftermeal, p = 0.0035) and 3.22 hours (1.5 hours postmeal, p = 0.0094). The only discernable difference in parameters between treatments C and D was with Cmax, with values of 7.19 and 9.04 ng/mL, respectively, but was not statistically significantly different (p = 0.231). Based on these results and those from a prior study, it is recommended that under therapeutic conditions, oral tacrolimus be administered in a consistent manner, both with respect to the type of meal as well as timing of ingestion relative to consumption of the meal.

Adult↗
PubMed2001

Comparative tacrolimus pharmacokinetics: normal versus mildly hepatically impaired subjects.

Tacrolimus (FK506, Prograf), marketed for the prophylaxis of organ rejection following allogenic liver or kidney transplantation, is virtually completely metabolized. The major metabolic pathways are P450 3A4-mediated hydroxylation and demethylation. Since P450 hepatic drug-metabolizing enzymes may be impaired in hepatic dysfunction, a study was conducted to characterize oral and intravenous tacrolimus pharmacokinetics in 6 patients with mild hepatic dysfunction and compared with parameters to those from normal subjects obtained in a separate study. Patients received two treatments: a single 0.020 mg/kg ideal body weight (IBW) i.v. dose infused over 4 hours and approximately 0.12 mg/kg IBW orally; normal subjects were dosed at 0.02 mg/kg 4-hour i.v. and 5 mg (0.065 mg/kg) p.o. Mean blood pharmacokinetic parameters with mild hepatic dysfunction were as follows: clearance = 0.035 L/h/kg, terminal exponential volume of distribution = 2.59 L/kg, terminal exponential half-life = 60.6 hours (i.v.), p.o. maximum blood concentration = 48.2 ng/mL, time of p.o. maximum blood concentration = 1.5 hours, and absolute bioavailability = 22.3%. The respective parameters in normal subjects were as follows: 0.040 L/h/kg, 1.91 L/kg, 34.2 hours (i.v.), 29.7 ng/mL, 1.6 hours, and 17.8%. Inasmuch as clearance and bioavailability were not substantially different from that in normal subjects, patients with mild hepatic impairment may initially be treated with conventional tacrolimus doses, with subsequent dosage adjustments based on response, toxicity, and therapeutic drug monitoring.

Body Weight↗
PubMed2000

Botulinum toxin antibody testing: comparison between the mouse protection assay and the mouse lethality assay.

Conventionally, the standard test for detection of antibodies against botulinum toxin (BT-A) has been the mouse lethality assay (MLA). Because this test has a number of disadvantages, a novel mouse protection assay (MPA) was recently introduced. We sought to compare the results of both tests. Forty-three samples from 38 patients with cervical dystonia and complete or partial subjective BT-A therapy failure underwent simultaneous MPA and MLA testing. Twenty-seven samples showed concordant results in both tests. Eleven of them were MPA- and MLA-positive and 16 MPA- and MLA-negative, resulting in a significant association of the dichotomous test results (Fisher exact test, p <0.01). Sixteen samples showed discordant results. All of those were MPA-positive and MLA-negative. This excess of MPA-positive results was also significant (Wilcoxon signed-rank test, p <0.001). Of the patients with MPA-positive samples, 62% had complete and 38% had partial therapy failure. Of the patients with MLA-positive samples, 90% had complete and 10% had partial therapy failure. MPA and MLA results show significant association. Statistical analysis and predominance of partial therapy failure in MPA-positive patients demonstrate higher sensitivity of MPA. With its methodologic advantages, its test parameter being more relevant to BT-A therapy, and its higher sensitivity, the MPA appears to be superior to the MLA.

Animals↗