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Biomedical subjects

C Fischer

Publications and source records attributed to C Fischer.

At least 235 records · Page 13Linked to original sources
PubMed1991

Dentine hypersensitivity: a review.

Dentine hypersensitivity is a relatively common pain condition. Local pulpal inflammation, traumatic oral hygiene and dietary habits have been considered in the etiology of dentine hypersensitivity. Dentine hypersensitivity is probably caused by a change in fluid flow in the dentinal tubules, which in turn excites the nerve endings located at the pulp-dentine border. Consequently, treatment success would depend on the prevention of fluid flow across the dentinal tubules (sodium fluoride, stannous fluoride, sodium monofluorophosphate, strontium chloride, sodium citrate, potassium oxalate, and resins/adhesives), or on the desensitization of the nerve endings located at the pulp-dentine border (potassium nitrate). Although a wide variety of treatment methods have been available, clinical data is characterized with ambiguity, warranting further research of the factors which could possibly be implicated in the occurrence of dentine hypersensitivity.

Citrates↗
PubMed1991

Clinical evaluation of pulp and dentine sensitivity after supragingival and subgingival scaling.

The exposure of dentinal tubules by the removal of root cementum on scaling procedures has been proposed to be a source of pulp injury and to cause dentine hypersensitivity. The aim of this study was to evaluate the sensitivity of the pulp and dentine after supragingival and subgingival scaling. Eleven patients with periodontally diseased mandibular incisors were selected. The subjects were divided into two groups according to marginal bone loss. The pulp sensitivity was evaluated by an electric pulp test. Dentine sensitivity was evaluated with two forms of controlled stimulations (probe and air-jet) and with a questionnaire. No changes in pulp sensitivity were found after scaling, but a clinically significant increase in dentine sensitivity to probe and/or air stimuli was observed in 6 patients. Five of these were also sensitive to daily life stimuli. A natural mechanism of desensitization seemed to have occurred two weeks after subgingival debridement. This study showed that supragingival and subgingival scaling might cause a more or less transient occurrence of dentine hypersensitivity.

Adult↗
PubMed1991

Intravascular ultrasound assessment of lumen size and wall morphology in normal subjects and patients with coronary artery disease.

BACKGROUND: Necropsy studies demonstrate that coronary artery disease (CAD) is frequently complex and eccentric. However, angiography provides only a silhouette of the vessel lumen. Intravascular ultrasound is a new tomographic imaging method for evaluation of coronary dimensions and wall morphology. Few data exist regarding intravascular ultrasound in patients with CAD, and no data exist for subjects with normal coronaries. METHODS AND RESULTS: We used a multielement 5.5F, 20-MHz ultrasound catheter to examine eight normal subjects and 43 patients with CAD. We assessed the safety of coronary ultrasound and the effect of vessel eccentricity on comparison of minimum luminal diameter by angiography and ultrasound. Normal and atherosclerotic wall morphology and stenosis severity were also evaluated by intravascular ultrasound. The only untoward effect was transient coronary spasm in five patients. At 33 sites in normal subjects, the lumen was nearly circular, yielding a close correlation between angiographic and ultrasonic minimum diameter (r = 0.92). At 90 sites in patients with CAD, ultrasound demonstrated a concentric cross section; correlation was also close (r = 0.93). However, at 72 eccentric sites, correlation was not as close (r = 0.77). For 41 stenoses, correlation between angiography and ultrasound for area reduction was moderate (r = 0.63). In normal subjects, wall morphology revealed a thin (0.30 mm or less) intimal leading edge and subadjacent sonolucent zone (0.20 mm or less). Patients with CAD exhibited increased thickness and echogenicity of the leading edge, thickened sonolucent zones, and/or attenuation of ultrasound transmission. CONCLUSIONS: These data establish that intravascular ultrasound is feasible and safe and yields luminal measurements that correlate generally with angiography. Differences between angiographic and ultrasound measures of lumen size in eccentric vessels probably reflect the dissimilar perspectives of tomographic and silhouette imaging techniques. Intravascular ultrasound provides detailed images of normal and abnormal wall morphology not previously possible in vivo.

Adult↗
PubMed1991

[Peroperative monitoring of early auditory evoked potentials in microsurgical vascular decompression for trigeminal neuralgia or hemifacial spasm].

Intra-operative B.A.E.P. monitoring have been performed in two series of patients who underwent Microsurgical Vascular Decompression (M.V.D.) of the Vth and VIIth cranial nerves in the posterior fossa. The first series consisted of 17 patients among the 400 operated on for Trigeminal Neuralgia (T.N.), the second one also of 17 patients among the 25 treated for Hemifacial spasm (H.S.), over the last four years. The equal number of recorded patients in the two groups is totally fortuitous. The aim of the work was to correlate the electrophysiological changes: 1) to the surgical manoeuvres potentially responsible for B.A.E.P. alterations, in order to modify the M.V.D. technique, so as to minimize the risks of hearing loss, 2) to the eventual post-operative auditory disturbances, in order to define prognostic criteria from B.A.E.P. monitoring. I. Intra-operative B.A.E.P. modifications were graded into 4 categories, according to their degree of severity (table II): minimal changes (category 1), increase in latency returning to normal (2) or without normalization (2a) before end of surgery, abolition or partial decrease of responses returning to normal (3) or without complete normalization (3a) before end of surgery, total B.A.E.P. loss lasting through the entire procedure (4). Patients operated on for H.S. had more often significant B.A.E.P. changes than those with T.N., respectively 10 and 6 for categories 3a and 4 together. Auditory function was at risk mainly during cerebellar retraction (especially if cerebello-pontine angle was approached laterally) and during vascular manipulation of the labyrinthine artery (which can generat vasospasm).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Value of early auditory evoked potentials after neurosurgery].

Recording brainstem auditory evoked potential (BAEP) in post operative period after neurosurgery is easy. The presence of abnormal BAEP predicts unfavorable outcome in both cases with or without sedation. But in case of normal recording it is impossible to predict surely a favorable outcome.

Adult↗
PubMed1991

Enantiomer/enantiomer interaction of (S)- and (R)-propafenone for cytochrome P450IID6-catalyzed 5-hydroxylation: in vitro evaluation of the mechanism.

Many drugs are used as racemates, and the enantiomers may differ in terms of pharmacological properties and disposition. Stereoselective disposition of the enantiomers can arise from metabolism of the enantiomers via different routes catalyzed by different enzymes. In contrast, the enantiomers may be metabolized by the same enzyme at different rates. In the latter case, the enantiomers can compete for this metabolic step, giving rise to the possibility of an enantiomer/enantiomer interaction. We have chosen the antiarrhythmic propafenone, for which in vivo data indicated an interaction between (S)- and (R)-propafenone, as a model substance to study the mechanism underlying that interaction in human liver microsomes. We used the cytochrome P450IID6-mediated 5-hydroxylation of propafenone as a model pathway, because this metabolic step constitutes the major route of biotransformation of propafenone. The Michaelis-Menten kinetics for 5-hydroxylation were determined after incubation of (R)- and (S)-propafenone and a pseudoracemate consisting of (S)-[2H4]propafenone and (R)-propafenone. Inhibition experiments were performed using (S)-[2H4]propafenone as an inhibitor of the 5-hydroxylation of (R)-propafenone, and vice versa. The kinetic model of mixed alternative substrates was used to simulate inhibition experiments. Experimental data were compared with those predicted by this model. We observed a substantial stereoselectivity after incubation of the individual enantiomers [(S)-propafenone: Vmax, 10.2 pmol/micrograms/hr, and Km, 5.3 microM; (R)-propafenone: Vmax, 5.5 pmol/micrograms/hr, and Km, 3.0 microM]. In contrast, no substrate stereoselectivity was observed after incubation of the pseudoracemate [3.1 pmol/micrograms/hr for (S)-[2H4]propafenone and 3.3 pmol/micrograms/hr for (R)-propafenone]. Application of the model revealed Ki values of 2.9 and 5.2 microM for the inhibition of 5-hydroxylation of (S)-[2H4]-propafenone by (R)-propafenone and for inhibition of 5-hydroxylation of (R)-propafenone by (S)-[2H4]-propafenone, respectively. The predicted and the experimental data were in good agreement, and both indicated the mode of inhibition to be competitive. In conclusion, the enantiomers of propafenone interact with respect to 5-hydroxylation, with (R)-propafenone being a more potent inhibitor than the S-enantiomer with respect to cytochrome P450IID6-mediated 5-hydroxylation. Because beta-blocking properties of propafenone reside in the S-enantiomer, inhibition of metabolism of this enantiomer by (R)-propafenone may have therapeutic consequences.

Adolescent↗
PubMed1991

Breast-feeding policies and routines among Arizona hospitals and nursery staff: results and implications of a descriptive study.

In 1988, Arizona's 61 hospitals providing obstetrical services were canvased with regard to hospital routines that favor either breast-feeding or bottle-feeding. Forty-five hospitals provided responses that were used in the survey. Practices favoring breast-feeding, which were reported by a majority of the hospitals (more than 50%), were demand feeding, staff assessment for "latch-on" (the action of nipple presentation and sucking initiation) and positioning, "rooming-in" (the practice of minimal mother-infant separation), and information about follow-up support services. Hospital practices suggested to promote bottle-feeding were the provision of pacifiers and supplemental water or glucose, issuance of formula packs at discharge, and a first feed of sterile water. A positive significant relationship was identified for policies advocating breast-feeding and the prevalence of breast-feeding encouragement from professional staff. Of 44 respondents, 41 indicated that their hospital's policies endorse breast-feeding as the ideal method of feeding healthy newborns. Hospital staff perceived that they encourage mothers to breast-feed and offer support to those who initiate breast-feeding. On the basis of this information, we conclude that dietetics practitioners should evaluate current breast-feeding practices and integrate policies supportive of breast-feeding into the health care system.

Arizona↗
PubMed1990

[Results of therapy in Hodgkin's disease].

The results of therapy in 239 patients (161 men, 78 women, median age 33 [13-80] years) who had been treated for Hodgkin's disease between 1972 and 1986 were evaluated retrospectively. The proportion of complete remissions depended on the stage of the disease and was 90% (35 out of 39 patients) for stage IA, 90% (9 out of 10) for stage IB, 84% (40 out of 48) for stage IIA, 88% (22 out of 25) for stage IIB and 86% (37 out of 43) for stage IIIA. At five and ten years, survival rates among patients in stages IA to IIB were 76 and 69%, respectively, and for patients in stage IIIA 81 and 52%, respectively. For patients who enjoyed complete remissions the probability of surviving for 5 or 10 years without recurrence was 62% or 54%, respectively, for stages IA to IIB, and 75 or 43%, respectively, for stage IIIA. There were no statistically significant differences between stages I, II and IIIA as regards remission rate, survival time or recurrence-free survival time. During these stages the patient's age proved to be the only prognostic factor of any statistical significance. For stages IIIB and for IVA and IVB the proportion of complete remissions achieved by combined chemotherapy with COPP was 62%. At 5 and 10 years the proportion of these patients in permanent remission was 63 and 53%, respectively, while survival rates in the entire series were 46% and 40%, respectively. A genuine cure--in the sense of at least 10 years' survival without recurrence after the first complete remission--can be expected in one third of patients in stages IIIB to IVB.

Adolescent↗
PubMed1990

[What is the recurrence rate for Basedow's disease treated with thyrostatic agents. Answers from a prospective study].

Graves' disease is an autoimmune disease whose development involves immunogenetic and exogenous factors such as viruses, bacteria and iodine excess. In a number of patients the disease follows a chronic recurrent course. A recurrence rate of 50% can be expected one year after the end of therapy. Based on the preliminary results of the prospective study presented here, this recurrence rate does not differ in groups where patients underwent long-term treatment with 10 or 40 mg thiamazole. Retrospectively obtained data suggest that the time at which euthyroidism occurs under low-dose treatment is dependent on the alimentary iodine supply. A number of groups have attempted to develop clinically applicable methods to identify patients at risk for recurrence at the end of treatment. All the studies yielded controversial results. A prospective multicenter study was undertaken to reinvestigate the importance of measuring TSH receptor antibodies and performing the TRH test and the suppression test at the end of therapy in connection with this problem. In 451 patients the recurrence rate was 50.3% one year after the end of treatment. The patients in the recurrence group had a significantly higher rate of persistent antibody activity, no increase in TSH after TRH (negative TRH test), no normal suppressibility of thyroid 123 iodine uptake (negative suppression test) and larger goiter. The calculation of sensitivities and specificities shows, however, that these differences are not large enough to be of clinical importance for the individual patient.

Autoantibodies↗
PubMed1990

Differences in heart rate and blood pressure in children with conduct disorder, major depression, and separation anxiety.

Heart rate and blood pressure of children and adolescents admitted to a psychiatric hospital were compared among those diagnosed conduct disorder, major depressive disorder, and separation anxiety disorder. Subjects with conduct disorder had a lower heart rate compared to subjects without a conduct disorder diagnosis; and subjects with separation anxiety disorder had higher heart rate and systolic blood pressure compared to subjects without an anxiety disorder diagnosis. Subjects with major depressive disorder had higher systolic blood pressure than subjects with conduct disorder but no difference in heart rate. The findings are consistent with conduct disorder being associated with decreased noradrenergic function and anxiety/depressive disorder being associated with increased noradrenergic function.

Adolescent↗
PubMed1990

[Intraoperative brainstem auditory evoked potential in the microvascular decompression of the 5th and 7th cranial nerves].

Microvascular decompression techniques are rational surgical procedures for treating trigeminal neuralgia and facial hemispasm, with results ranging from good to excellent in 90% of cases. Among the most frequent complications recorded in the literature concerning these decompressions, impairment of the facial nerve and auditory nerve account for 5% to 10% due to mechanical traction and/or vascular injury. The peroperative use of early brain-stem evoked potentials (BAEP) was performed on 17 patients in a series of 325 decompressions of the trigeminal nerve, and on 17 patients in a series of 25 decompressions for facial hemispasm. Such peroperative monitoring is considered to be most important in the surgical technique. The author reports on his experience and results.

Adult↗
PubMed1990

[Contribution of magnetic resonance imaging in 100 cases of refractory partial epilepsy with normal CT scans].

One hundred epileptic patients were included in this study according to the following criteria: intractable partial epilepsy, normal CT scan and focal EEG abnormalities. Eighty-nine patients were suffering from complex partial seizures of temporal or frontal origin, 55 and 34 cases respectively. Eleven patients presented with only simple partial seizures. MRI was abnormal in 31 patients. The abnormalities were: focal T2 increased signal intensity (13 cases) most often temporal (10 cases), cryptic arteriovenous malformation (4 cases), focal T1 and T2 signal abnormality (4 cases), focal atrophy (2 cases) and multiple abnormal T2 signals scattered in the white matter (8 cases). The site of MRI abnormalities was consistent with electroclinical data in 22 patients, of whom 20 had a temporal lobe epilepsy. Thus MRI proved to be more often abnormal in temporal than in frontal lobe epilepsy (36 p. 100 and 5.9 p. 100 respectively) when the CT scan is normal. However MRI data, particularly focal T2 hypersignals should be confronted to electroclinical and metabolic findings whenever functional surgery is considered.

Adolescent↗
PubMed1990

Mechanism of binding and uptake of sialidase-treated blood cells and glycoproteins by the galactose-specific receptor of rat peritoneal macrophages.

Sialidase-treated rat erythrocytes, lymphocytes and thrombocytes bind to homologous peritoneal macrophages via demasked, terminal galactose residues on the blood cells and a galactose-specific receptor on macrophages. While erythrocytes and thrombocytes are phagocytosed after binding, vital lymphocytes are released from the phagocytes after several hours of incubation, because their surface sialic acids are resynthesized. Asialoglycoprotein-coated gold-particles are also bound, and the pathway of their internalization and recycling of the receptor was studied using various inhibitors of endocytosis. Sialidase treatment of macrophages abolished their binding capacity.

Animals↗
PubMed1990

Interaction of verapamil and cimetidine: stereochemical aspects of drug metabolism, drug disposition and drug action.

The pharmacokinetics, metabolism and pharmacodynamics of verapamil (160 mg p.o. of a pseudoracemic mixture) were evaluated in six healthy volunteers before and after coadministration of cimetidine (400 mg b.i.d.). Enantiomers of verapamil and enantiomers of three major urinary metabolites (norverapamil, D-617 and D-620) were determined in plasma and urine by gas chromatography-mass spectrometry. Coadministration of cimetidine led to a significant increase in the area under the plasma concentration vs. time curve of S-verapamil (29.2 +/- 31.8 min x nmol x ml-1 vs. 41.2 +/- 33.7 min x nmol x ml-1; P less than .003) and R-verapamil (124.7 +/- 112.2 min x nmol x ml-1 vs. 156.8 +/- 105.0 min x nmol x ml-1; P less than .01). The increase was significantly greater for the pharmacologically more potent S-enantiomer compared to R-verapamil (150.3 +/- 37 vs. 117.8 +/- 15%; P less than .05). As a consequence, coadministration of cimetidine increased the negative dromotropic effect of verapamil on atrioventricular conduction in five of six subjects. In addition, fractional metabolic clearance to D-620 and D-617 decreased for both enantiomers. Tubular secretion of S-D-617 was inhibited by cimetidine (342 +/- 104 vs. 238 +/- 52 ml x min-1; P less than .05) whereas secretion of the R-enantiomer remained unchanged (276 +/- 91 vs. 222 +/- 43 ml x min-1). Thus, cimetidine interacts with both hepatic and renal verapamil elimination in a stereoselective manner. The increase in total plasma concentration of verapamil combined with an increase in eutomer/distomer ratio produces a more pronounced pharmacological effect of verapamil when cimetidine is coadministered.

Administration, Oral↗
PubMed1989

Detection of desmethyldiazepam and diazepam in brain of different species and plants.

Recent data suggest that desmethyldiazepam (DD), a major metabolite of several benzodiazepines (BZD), might be of natural origin. Therefore we tried to quantify DD and diazepam (D) in animals during maturation (e.g. hen, chicken, eggs), in brain of species at different evolutionary stages e.g. salmon, frog, monitor/reptile, rat, cat, dog, deer, bovine) including newborn and adult humans. Since low concentrations of DD (range 0.01-0.04 ng/g wet wt) and D (range 0.005-0.02 ng/g) could be measured in different species by sensitive and specific mass spectrometry (GC-MS), we analysed also several plants (e.g. maize corn, lentils, potatoes, soybeans, rice, mushrooms). Again, DD and D could be detected in low amounts (0.005-0.05 ng/g) in some plant products. This would suggest that DD and D might be of natural origin and incorporated via the foodchain into the animal and human body. The biological role or clinical relevance of these intriguing findings need still to be elucidated.

Animals↗