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Biomedical subjects

H Steffen

Publications and source records attributed to H Steffen.

At least 37 records · Page 2Linked to original sources
PubMed1999

Comparison of measurements obtained with hand files or the Canal Leader attached to electronic apex locators: an in vitro study.

AIM: The aim of the present in-vitro study was to combine directly the Canal Leader handpiece (SET, Olching, Germany) with the electronic apex locators ROOT ZX (Morita, Kyoto, Japan) and JUSTY (Yoshida, Tokyo, Japan) to find out whether the working length values thus obtained were identical to those resulting from the combination of the same electronic devices with hand files. METHODOLOGY: A total of 50 natural extracted teeth with single canals and mature apices were used. A radiograph was used as a control and the distance from the radiographic apex to the tip of the file was measured and compared with the results of the electronic length determination. RESULTS: For both electronic devices the differences amongst the distribution of the measurements were not statistically significant under the specified conditions (P > 0.05), indicating that the measurements with hand files and with the Canal Leader were identical for the majority of the cases. CONCLUSIONS: Under the conditions of this study the working length of canals obtained with electronically assisted hand files were similar to those obtained with the electronically assisted mechanical handpiece Canal Leader.

Dental Equipment↗
PubMed1998

Active apical secretory efflux of the HIV protease inhibitors saquinavir and ritonavir in Caco-2 cell monolayers.

PURPOSE: To investigate in vitro the mechanisms involved in the gastro-intestinal absorption of the HIV protease inhibitor, saquinavir mesylate (Invirase), whose oral bioavailability is low, variable, and significantly increased by co-administration with ritonavir, also an HIV protease inhibitor but with higher oral bioavailability. METHODS: Confluent epithelial layers of human Caco-2 cells mimicking the intestinal barrier. RESULTS: Both saquinavir and ritonavir showed polarized transport through Caco-2 cell monolayers in the basolateral to apical direction (secretory pathway), exceeding apical to basolateral transport (absorptive pathway) by factors of 50-70 and 15-25, respectively. Active efflux was temperature dependent, saturable and inhibited by verapamil and cyclosporin A. Saquinavir and ritonavir decreased each other's secretory permeability and hence elevated their net transport by the absorptive pathway. CONCLUSIONS: Saquinavir and ritonavir are both substrates for an efflux mechanism in the gut, most likely P-glycoprotein, which acts as a counter-transporter for both drugs. Together with sensitivity to gutwall metabolism by cytochrome P-450 3A, this may partially account for the low and variable oral bioavailability of saquinavir in clinical studies and for its increased bioavailability after co-administration with ritonavir.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Familial congenital horizontal gaze paralysis and kyphoscoliosis.

Congenital horizontal gaze paralysis is a rare disorder which may be associated with severe scoliosis of early onset. We present the clinical findings of two sisters with this syndrome. The additional finding of a unique pericentric inversion of chromosome 12 is considered to be incidental. Every child with congenital horizontal gaze paralysis should be evaluated for a possibly associated scoliosis. If present, a diagnosis of this presumably autosomal recessive syndrome can be made with appropriate treatment and genetic counseling.

Child↗
PubMed1998

Posterior fixation suture and convergence excess esotropia.

The present study investigates the results of Cuppers' 'Fadenoperation' in patients with non-accommodative convergence excess esotropia. Particular attention is given to postoperative eye alignment at distance fixation. Group 1 (n=96) included patients with a 'normal' convergence excess. The manifest near angles (mean ET 16.73 degrees +/- 6.33 degrees, range 4 degrees -33 degrees ) were roughly twice the size of the distance angles (mean ET 6.50 degrees +/- 3.62 degrees, range 0 degrees -14 degrees ). These patients were treated with a bilateral fadenoperation of the medial recti without additional eye muscle surgery. Three months after surgery, the mean postoperative angles were XT 0.5 degrees +/- 3.3 degrees (range XT 11 degrees -ET 5 degrees ) for distance fixation, and ET 2.7 degrees +/- 3.6 degrees (range XT 5 degrees -ET 14 degrees ) for near fixation, respectively. Postoperative convergent angles at near fixation >ET 10 degrees were present in two patients (1.9%). Group 2 (n=21) included patients with a mean preoperative distance angle of ET 9.2 degrees +/- 3.7 degrees (range 6 degrees -16 degrees ) and a mean preoperative near angle of ET 23.4 degrees +/- 3.1 degrees (range 16 degrees -31 degrees ). These patients were operated on with a bilateral fadenoperation of the medial recti and a simultaneous recession of one or both medial rectus muscles. Mean postoperative angles were XT 0.5 degrees +/- 4.6 degrees (range XT 12 degrees -ET 7 degrees ) for distance fixation and ET 1.4 degrees +/- 4.5 degrees (range XT 8 degrees -ET 13 degrees ) for near fixation, respectively. In this group, 2 patients (10.6%) had a postoperative exotropia >XT 5 degrees at distance fixation, and two patients had residual esotropia>ET 10 degrees at near fixation. Group 3 (n=17) included patients with a pronounced non-accommodative convergence excess. Near angle values (mean of 17.8 degrees +/- 5.3 degrees, range ET 7 degrees -26 degrees ) were several times higher than the distance angle values (mean ET 1.9 degrees +/- 4.2 degrees, range XT 3 degrees -ET 6 degrees ). These patients were treated with a bilateral fadenoperation of the medial recti and a simultaneous resection of one or both medial rectus muscles. Mean postoperative angles were ET 0.2 degrees +/- 4.7 degrees (range XT 8 degrees -ET 6 degrees ) for distance fixation and 5.3 degrees +/- 6.1 degrees (range XT 3 degrees -ET 12 degrees ) for near fixation, respectively. One patient had a postoperative distance angle >XT 5 degrees, whereas two patients displayed postoperative convergent angles >ET 5 degrees at near fixation.

Journal Article↗
PubMed1998

[Comparison of addition of theophylline to inhaled steroid with doubling of the dose of inhaled steroid in asthma].

The anti-asthmatic effect of theophylline may supplement those of inhaled steroids in asthma. The aim of the present trial was to study how the addition of theophylline compares to doubling the dose of inhaled steroid in asthmatics who remain symptomatic on beclomethasone dipropionate (BDP) 400 micrograms/day. The trial was designed as a randomized, double-blind, parallel-group study in several European countries. 69 patients were treated for 6 weeks with theophylline plus BDP 400 micrograms/day, compared to 64 patients treated with BDP 800 micrograms/day. The mean +/- SD serum theophylline concentration was 10.1 +/- 4.2 mg/l. Lung function measurements were made throughout the study and patients kept daily records of peak expiratory flow rate (PEF), symptoms and salbutamol usage. Forced expiratory volume in one second and PEF at week 6 were significantly increased by both treatments (p < 0.01). PEF variability was reduced by about 30% in both groups. There were significant improvements in asthma symptoms and rescue medication use (p < 0.001). There were no significant differences between the treatment groups. The study demonstrated clinical equivalence of theophylline plus beclomethasone dipropionate 400 micrograms/day and beclomethasone dipropionate 800 micrograms/day in patients whose asthma is not controlled on beclomethasone dipropionate 400 micrograms/d. The results support the use of theophylline as steroid-sparing agent. The combination of low-dose inhaled steroid plus theophylline is a suitable treatment for moderate asthma.

Adolescent↗
PubMed1998

Effect of horizontal vergence on the motor and sensory components of vertical fusion.

PURPOSE: To compare motor and sensory capabilities for fusion of vertical disparities at different angles of horizontal vergence in healthy humans. METHODS: Eye movements were recorded from both eyes of 12 healthy subjects using three-axis search coils. The stimulus was a cross (+) (3.4 x 3.2 degrees , vertically and horizontally, respectively) presented to each eye with a stereoscopic display. Vertical disparities were introduced by adjusting the vertical position of the cross in front of one eye. The disparity was increased in small increments (0.08 degrees ) every 8 seconds. Viewing was defined as "near" if there was a horizontal disparity that elicited 6 degrees to 15 degrees convergence, depending on the subject's capability for horizontal fusion; viewing was defined as "far" at 1 degrees convergence. Maximum motor (measured), sensory (stimulus minus motor), and total (motor plus sensory) vertical fusion were compared. RESULTS: In 9 (75%) of 12 subjects the maximum total vertical fusion was more in near than in far viewing. The three who did not show this effect had relatively weak horizontal fusion. For the entire group, the motor component differed significantly between far (mean, 1.42 degrees ) and near (mean, 2.13 degrees). Total vertical fusion capability (motor plus sensory) also differed significantly between far (mean, 1.68 degrees ) and near (mean, 2.39 degrees ). For the sensory component there was no difference between between far (mean, 0.268 degrees ) and near (mean, 0.270 degrees ). As vertical disparity increased in a single trial, however, there was a small gradual increase of the contribution of the sensory component to vertical fusion. CONCLUSIONS: Vertical fusion capability usually increases with convergence. This increase is caused primarily by an increase in the motor component. There is a gradual but small increase in the sensory component as target disparity slowly increases.

Adult↗
PubMed1997

[Carcinoma-associated retinopathy in breast carcinoma and carcinoid tumor].

BACKGROUND: Carcinoma-associated retinopathy (CAR) is a rare paraneoplastic syndrome characterized by diffuse retinal photoreceptor degeneration in the presence of an epithelial tumor. We report on three patients, who developed paraneoplastic retinopathy in the presence of breast carcinoma and a cervical carcinoid tumor. MATERIALS AND METHODS: In addition to biomicroscopic, psychophysical, electrophysiological and angiographic examinations, serum samples were obtained for immunohistochemical staining of human retina. RESULTS: Ring-shaped visual field defects with statokinetic dissociation and abnormal rod and cone responses were found. Immunohistochemical findings included reactions at the level of the inner segments of the photoreceptors, the outer nuclear layer and the outer plexiform layer in absence of anti-recoverin antibodies. CONCLUSIONS: CAR should be considered in the differential diagnosis of visual loss in presence of tumors other than small-cell carcinoma of the lung. The presence of antiretinal antibodies is compatible with a tumor-induced immune response to epitopes shared by both the tumor and retinal tissue. Apparently, various retinal proteins may function as autoantigens.

Adult↗
PubMed1997

[Effect of a local nonsteroidal anti-inflammatory drug on postoperative irritation after squint surgeries. Prospective randomized double-blind study].

BACKGROUND: Topical application of a nonsteroidal antiphlogistic drug (NSAD) is often recommended to minimize postoperative lid and conjunctival edema. However, the effectiveness of such therapy remains controversial. PATIENTS AND METHODS: The study presented included 100 patients aged 23.6 +/- 19.5 (5 to 77) years, who were randomly assigned to two treatment groups. Group 1 included 50 patients who underwent squint surgery, and who received Flurbiprofen ED twice a day from the first preoperative day to the third postoperative day. Group 2 served as a control group. These patients were treated with the same regimen using artificial tears. The extent of lid and conjunctival edema was assessed and scored from 1 to 4 on the fourth postoperative day. RESULTS: Squint surgery was performed on 129 eyes of 100 patients. In 32 eyes (24.8%) one muscle was operated on. In 79 eyes (61.2%) 2 muscles and in 18 eyes (14%) three muscles were operated on. The average postoperative conjunctival edema score was 2.08 +/- 0.62 (Flurbiprofen group) and 2.04 +/- 0.67 (control group), respectively. The scoring values for lid edema were 1.90 +/- 0.54 and 1.82 +/- 0.43. The differences between the two groups were not statistically significant (P = 0.21 and 0.39; Mann-Whitney test). No influence of the patient's age on the development of lid and conjunctival edema could be detected (P > 0.08). However, the number of muscles that were operated on had a significant influence on both parameters (P = 0.01 and 0.028). Single muscle operations revealed the lowest scaling values (P < 0.02 and P < 0.04). No difference was found whether 2 or 3 muscles were operated on (P = 0.24 and 0.12). CONCLUSIONS: No beneficial effect of topical application of NSAD on postoperative lid and conjunctival edema could be found in this controlled study.

Adolescent↗
PubMed1997

Sebaceous-gland deposition of isotretinoin after topical application: an in vitro study using human facial skin.

As yet, topically applied isotretinoin fails to show convincing clinical efficacy in the treatment of severe recalcitrant acne. Although the reason for this is not known, it is possible that topical application results in low, pharmacologically inactive isotretinoin concentrations in the sebaceous glands, the most likely site of isotretinoin action. It has been suggested that topically applied liposomes enhance the delivery of drugs into the sebaceous glands. Accordingly, we compared the isotretinoin concentration in sebaceous glands and other skin compartments following topical application of small unilamellar vesicles, multilamellar vesicles, preformed vesicles (Natipide II) or mixed micelles of lecithin and bile salt. We found that the concentration of isotretinoin measured in the sebaceous glands varied between 0.17 and 1.57 ng/mg tissue. The comparison between ethanolic gel and liposomal or micellar gel did not reveal any significant difference. However, application of the Natipide formulation resulted in significantly lower isotretinoin concentrations in the sebaceous glands when compared to the ethanolic gel. Autoradiography and fluorescence microscopy indicated that isotretinoin penetrated the sebaceous glands along the follicular route. In conclusion, our in vitro study showed that, following topical administration, substantial amounts of isotretinoin were delivered to the sebaceous glands via the follicular route, whereby the ethanolic gel was as efficient as a liposomal or a mixed micellar gel.

Administration, Topical↗
PubMed1997

Comparison of addition of theophylline to inhaled steroid with doubling of the dose of inhaled steroid in asthma.

The anti-asthmatic effects of theophylline may supplement those of inhaled steroids in asthma. The aim of the present trial was to study how the addition of theophylline compares to doubling the dose of inhaled steroid in asthmatics who remain symptomatic on beclomethasone dipropionate (BDP) 400 microg x day(-1). The trial was designed as a randomized, double-blind, parallel-group study in several European countries. Sixty nine patients were treated for 6 weeks with theophylline plus BDP 400 microg x day(-1), compared to 64 patients treated with BDP 800 micro x day(-1). The mean+/-SD serum theophylline concentration was 10.1+/-4.2 mg x L(-1). Lung function measurements were made throughout the study and patients kept daily records of peak expiratory flow (PEF), symptoms and salbutamol usage. Forced expiratory volume in one second and PEF at week 6 were significantly increased by both treatments (p<0.01). PEF variability was reduced by about 30% in both groups. There were significant improvements in asthma symptoms and rescue medication use (p<0.001). There were no significant differences between the treatment groups. The study demonstrated clinical equivalence of theophylline plus beclomethasone dipropionate 400 microg x day(-1) and beclomethasone dipropionate 800 microg x day(-1) in patients whose asthma is not controlled on beclomethasone dipropionate 400 microg x day(-1). The results support the use of theophylline as a steroid-sparing agent. The combination of low-dose inhaled steroid plus theophylline is a suitable treatment for moderate asthma.

Administration, Inhalation↗
PubMed1996

The diagnostic value of optic disc evaluation in acute elevated intracranial pressure.

PURPOSE: Ophthalmologists often are asked to evaluate the optic disc for evidence of acute increased intracranial pressure (ICP). The authors studied the incidence of papilledema in a population of patients with a documented acute increase in ICP. METHODS: Included in this study were 37 patients with acute elevated ICP due to a spontaneous hemorrhage or craniocerebral trauma. In all patients, the ICP was monitored continuously. Fundus examination was performed twice daily on at least 7 consecutive days. RESULTS: According to the level and duration of the ICP, the patients were divided into three groups. Group 1 included 13 patients who had a slightly elevated ICP (range, 20-30 mmHg) on at least 3 consecutive days. In this group, 3 of 13 patients demonstrated venous congestion on the fifth or sixth day. No swelling of the optic disc was seen in this group. Group 2 included seven patients with an elevated ICP, with values ranging from 30 to 70 mmHg lasting for at least 3 consecutive days. In this group, one patient had a blurred disc margin on the sixth day. Group 3 included 17 patients with shortlasting ICP values, ranging from 30 to 60 mmHg for less than 72 hour. Neither papilledema nor abnormalities of fundus vessels were seen in this group. CONCLUSION: Papilledema in acute elevation of ICP is an uncommon event. Its absence does not preclude the presence of ICP elevation.

Acute Disease↗
PubMed1996

Hyperthermia induces heat shock protein expression and protection against cerulein-induced pancreatitis in rats.

BACKGROUND & AIMS: Heat shock proteins (HSPs) are part of the cellular stress response machinery. HSPs are expressed in the pancreas, but their protective potential has not been thoroughly investigated. The aim of this study was to characterize the pancreatic heat shock response both in vitro and in vivo and to study whether this response has protective effects. METHODS: For in vitro experiments, rat pancreatic acini were exposed to heat and protein expression was analyzed through 35S-methionine labeling or Western blots. In vivo, cerulein pancreatitis was induced after whole body hyperthermia (42 degrees C). RESULTS: After thermal stress (42 degrees C), acini increasingly expressed five proteins of 92, 72, 59, 58, and 30 kilodaltons, with HSP. 70 the most strongly induced 72-kilodalton protein. In vivo, increased expression of four isoforms of pancreatic HSP-70 was found. Isoform-specific antibodies identified the inducible and constitutively expressed (HSC-70) isoform of HSP-70. HSP-60 was also weakly induced after hyperthermia. Concomitantly, cerulein-induced pancreatic organ damage was greatly reduced after whole-body hyperthermia. The time course and strength of HSP induction correlated well with the time course and degree of protection against cerulein-induced pancreatitis. CONCLUSIONS: A causal relation between hyperthermia-induced HSP expression and organ protection seems possible.

Animals↗
PubMed1996

Juvenile progressive scoliosis and congenital horizontal gaze palsy.

Eleven articles reporting 39 patients with the combination of progressive scoliosis and familial congenital gaze palsy have now been published. This disorder appears to be caused by a malfunction of the normal equilibrial control mechanism related to the brainstem or the central nervous system. The scoliosis progresses when the children begin to walk. Even when they are treated with physiotherapy or brace, they often require early operation. We consider that progressive juvenile or infant scoliosis associated with familiar congenital horizontal gaze palsy constitutes a clinical entity. We report two sisters with congenital gaze palsy, in one of whom scoliosis of at least 70 degrees (Cobb) developed, and review and analyze all cases published until now.

Child, Preschool↗
PubMed1996

[Familial congenital horizontal gaze paralysis].

Familial congenital horizontal gaze paralysis is a rare disorder supposedly transmitted in an autosomal recessive fashion. Typically, all horizontal, conjugate eye movements are absent. Most patients are orthotropic with regular binocular function. The complete lack of horizontal eye movements is compensated for by turning the head in the desired direction. Another compensating mechanism is the use of convergent eye movements, when horizontal gaze is attempted. Eye movements in the vertical plane are only mildly affected. The majority of patients suffer from a scoliosis that manifests itself in early infancy and usually requires operative treatment. Maldevelopment of neurons of the abducens nuclei and the caudal longitudinal fascicle is said to be the cause. The possible outcome of the disease and the importance of a prompt diagnosis are discussed.

Abducens Nerve↗
PubMed1996

[Acquired vertical diplopia in macular dystrophy as a model for obligate fixation disparity].

In patients with obligate fixation disparity central objects may be perceived as double when peripheral fusion is achieved. The diplopia cannot be resolved with prisms because the fusional power of the periphery is stronger than the central power. A different cortical integration of the peripheral and central parts of the retina is thought to be the underlying cause. We report on the clinical findings in a 45-year-old man with macular dystrophy who complained of binocular vertical diplopia of up to 1 degree. Investigation with the phase-difference haploscope revealed inhomogeneous retinal correspondence in the vertical plane, with a displacement of the visual field center relative to the periphery by 0.6 degrees. We suggest that paracentral scarring had caused displacement of receptors such that the center and the periphery could not be fused simultaneously. The case represents a model for a retinal origin of fixation disparity.

Convergence, Ocular↗
PubMed1995

When should isolated liver transplantation be performed in primary hyperoxaluria type 1? Follow-up report of two children.

The value of isolated liver transplantation in primary hyperoxaluria type 1 (PH1) and its timing are controversial. Two children with PH1 were followed up for 6 years after liver transplantation. A boy aged 5 years with a glomerular filtration rate (GFR) of 65 ml/min/1.73 m2 at the time of transplantation subsequently showed regression of calcium deposits in the kidneys, but GFR slightly declined, probably related to cyclosporin A toxicity. A girl with a severe neonatal form of PH1 received a liver at the age of 2 years when GFR had already declined to about 15 ml/min/1.73 m2 and extrarenal manifestations (bones, eyes) were present. In spite of these and further complications post-transplantation GFR stabilized. Growth failure was efficiently treated by growth hormone. Plasma and urinary oxalate concentrations, however, remained increased. It is suggested that in PH1 liver transplantation should be considered only if GFR is not rapidly declining and stays above 30 ml/min/1.73 m2. For an individual decision the different risks of liver transplantation and of combined kidney-liver transplantation as well as the possible benefits from previous conservative treatment must be considered.

Child, Preschool↗