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Biomedical subjects

M Wenzel

Publications and source records attributed to M Wenzel.

At least 19 recordsLinked to original sources
PubMed1997

Angiotensin-converting enzyme inhibitors in preventing remodeling and development of heart failure after acute myocardial infarction: results of the German multicenter study of the effects of captopril on cardiopulmonary exercise parameters (ECCE).

Early action of angiotensin-converting enzyme (ACE) inhibitors after myocardial infarction (MI) has been shown in large scale clinical trials to reduce mortality over the first weeks. However, the mechanisms involved are yet unclear and several trials showed a tendency toward a small, albeit unexpected, rise in cardiogenic shock or mortality. Since cardiopulmonary exercise testing (CPX) has become a "gold standard" in assessing the severity of heart failure, we studied--after finishing a pilot trial--the effect of captopril versus placebo in 208 patients who were individually titrated (titrated dose, mean 46/69 mg/day after 7 days/4 weeks, respectively) in order to preserve their blood pressure in the acute phase of myocardial infarction; we followed the development of congestive heart failure (CHF) over 4 weeks by measuring oxygen consumption. After 4 weeks, overall oxygen consumption at the anaerobic threshold (VO2-AT; 13.7 vs 13.1), maximal oxygen consumption (VO2max 19.3 vs 18.9 mL/kg per min) and exercise duration (896 vs 839 sec) showed a nonsignificant difference in favor of the captopril group. The predefined, categorized, combined endpoint of severe heart failure or death (heart failure necessitating ACE inhibition, VO2max < 10 mL/kg per min, or death) was significantly reduced in the captopril group (n = 7/104) versus placebo (n = 18/104; p = 0.03). Differences were mainly caused by fewer CHF events (delta n = 10). We conclude that ACE inhibition with individualized dose titration markedly reduces the 4-week incidence of severe heart failure or death; > 10 patients per 100 treated gained major benefits from this therapy.

Adult↗
PubMed1997

[Anemia increases work of breathing in patients with lung disease].

BACKGROUND: Pulmonary diseases with marked disorders in gas exchange or chronic overload of the respiratory pump needs increased ventilatory requirements. Additionally in these patients anemic may aggravate the ventilatory load. We thereby evaluated whether in these patients treatment of anemia (red blood cell transfusion: RBCT) leads to an improvement of the ventilatory load in comparison to the anemic patients without pulmonary disease. PATIENTS AND METHODS: We examined 21 patients with an anemia (Hb < 11 g%, 12 men). Fifteen patients had a pulmonary disease (group A), 6 patients suffered from anemia without pulmonary disease (group B). Subsequently within 8 hours the patients got 2 to 3 RBCT. We studied the patients on the day of admission and 24 to 36 hours after transfusion. The patients kept bed rest for spontaneous breathing 1 hour prior to the actual examination without supplemental oxygen. Hemoglobin, hematocrit, respiratory rate, respiratory minute volume and arterial blood gases were measured. On the following day we repeated the same procedures. RESULTS AND CONCLUSIONS: Anemia in patients with an increased ventilatory requirement causes an additional increase of work of breathing. In these patients-in contrast to patients without compromised lungs-2.2 red blood cell transfusions lead to an impressive reduction of VE (about 20%) and correspondingly also to a reduction of WOB.

Aged↗
PubMed1997

[Endoscopic placement of an intratracheal oxygen catheter--description of a new method].

BACKGROUND: In patients with disturbed gas-exchange intratracheal oxygen insufflation improves oxygenation and reduces the minute ventilation. Until now the intratracheal oxygen insufflation was performed using a tracheostomy or a percutaneous transtracheal technique. We studied the acceptance and efficacy of the intratracheal oxygen insufflation using a bronchoscopic technique of intratracheal catheter placement. PATIENTS AND METHODS: Five COPD-patients (4 men, 55.2 +/- 10.3 years; FEV1: 0.9 +/- 0.31 = 30.3 +/- 5.5% debit, pO2: 56.2 +/- 10.3 mmHg, pCO2 +/- 43.1 +/- 4.8 mmHg). Procedure of catheter placement: Through a nasally passed bronchoscope a guide wire was inserted into the proximal part of one bronchus. When positioned at the point 2 to 3 cm proximal to the carina, the bronchoscope was marked with plaster at the nasal ostium in order to measure this distance. After removing the endoscope, the oxygen catheter was inserted proximal to the carina using the guide wire. Before and during the intratracheal oxygen insufflation (flow: 3 l/min) minute ventilation, tidal volume, breathing frequence, blood gases and the subjective scores (using a visual analogue scale) were measured. RESULTS: Apart from one patient with a tolerable spontaneous declining urge to cough irritation the catheter was tolerated well during the study. Whereas pCO2 remained stable during the ITO2 (before ITO2: 43.1 +/- 4.8 mmHg; after 1 hour ITO2: 44.3 +/- 4.8 mmHg), the oxygenation improved (pO2: 56.2 +/- 10.3; 81.4 +/- 19.6 mmHg) and the minute ventilation decreased (7.5 +/- 1.8; 5.4 +/- 1.3 l/min) by approximately 28%. CONCLUSION: The bronchoscopic application of the intratracheal oxygen catheter was characterized by high acceptance, low invasiveness and immediate function. Furthermore, the minute ventilation and work of breathing respectively decreased to a relevant degree.

Adult↗
PubMed1997

[Value of various intra- and extraoral therapeutic procedures for treatment of obstructive sleep apnea and snoring].

BACKGROUND: Recently intra- and extraoral devices are increasingly used in order to treat obstructive sleep apnea (OSA) and snoring. We examined the value of some devices according to the literature and our own results. PATIENTS AND METHODS: The mandibular advancing devices aim at increasing upper airway diameter. The active part of the tongue extending device (SnorEx) is a stamp connected to a piston which exerts pressure at the base of the tongue causing its forward displacement; we studied 23 patients. The principle of an optically stimulating system ("eye-cover", Snore-Stop) consists of a microphone and light diods which are integrated in the eye-cover. After detecting acoustic signals (for example snoring) optical stimuli are generated in front of the eyes, which are thought to induce arousals causing a change of body position and the reduction of the snoring and apneas; we measured 24 patients. The principle of the tongue-retainer (Snore-Master) is the fixation of the tongue in a ventral position, which is thought to enlarge the mesopharyngeal area; we studied 14 patients. The nose plaster (Breathe-Right) contains an elastic spine that pulls the alae nasi cranial. This manipulation is thought to increase the diameter of the nostril and reduce the airway resistance. We measured 30 patients with obstructive sleep apnea and 20 snoring subjects without obstructive sleep apnea. RESULTS: Regarding the mandibular advancing due to different appliance designs and study protocols variable success rates have been documented. In patients with mild to moderate obstructive sleep apnea a reduction of the sleep related breathing disorder could be shown. Non compliance (NC) to the tongue extending device was 75% (17/23). Non-compliance-patients were characterized by unacceptable local-side-effects of the prosthesis, lacking improvement of symptoms and of the respiratory disturbance index. Both tongue-retainer and -extensor are characterized by a high incidence of local side effects. Neither the eye-cover nor the nose plaster could improve the severity of obstructive sleep apnoe or snoring. In contrast to another study we could not show a significant effect of the tongue-retainer. CONCLUSIONS: Neither the nose plaster nor the optical stimulating device influenced the degree of obstructive sleep apnea and snoring. There are conflicting data regarding the tongue retainer. The high rate of non-compliant subjects and the low efficacy of the tongue extending prosthesis precludes large-scale use of this treatment modality in patients with obstructive sleep apnoe and snoring. In selected individuals suffering from a mild to moderate degree of obstructive sleep apnea with CPAP-inefficiency and -incompliance the mandibular advancing principle may be an therapeutic alternative to CPAP.

Equipment Design↗
PubMed1997

Screening for renal carcinoma associated mutations in the von Hippel-Lindau tumor suppressor gene by temperature gradient gel electrophoresis.

Renal cell carcinoma is the most common neoplastic disease of the adult kidney and occurs in its sporadic and hereditary form. Approximately 57% of all renal carcinomas of the clear cell type analyzed revealed a mutation in the von Hippel-Lindau disease (VHL) gene. In the present work, temperature gradient gel electrophoresis (TGGE) is presented as a rapid and precise polymerase chain reaction (PCR)-employing methodology for the detection of mutations in the VHL gene. The theoretical efficiency of TGGE to detect mutations in every base pair of the gene was calculated. According to computer analysis, at least 92% of all known mutations in the VHL gene are detectable. This calculated figure appears to be in agreement with the experimental results. Primary difficulties in analyzing exon 1 of the VHL gene were overcome by the employment of psoralen-cross-linked PCR fragments. In addition, TGGE analysis was used in screening for possible mutations in thirteen renal carcinoma samples. With this protocol TGGE is successfully added to the array of methods for the screening of VHL mutations.

Aged↗
PubMed1997

Endoscopic placement of a tracheal oxygen catheter: a new technique.

OBJECTIVE: In patients with chronic obstructive pulmonary disease (COPD), intratracheal oxygen insufflation (ITO) is an established therapeutic approach. We developed a new endoscopic technique of intratracheal catheter placement. The aim of this pilot study was to demonstrate its short-term feasibility in acutely extubated patients with moderate to severe COPD who require oxygen therapy. DESIGN: A guide wire was inserted through a nasally passed bronchoscope and was positioned such that its tip was placed intratracheally. Using a "Seldinger technique", the tracheal catheter was then inserted over the wire to a point 2-3 cm proximal to the carina and positioned under direct vision from the bronchoscope inserted through the contralateral nose. After catheter insertion, the guide wire was removed. The patients scored catheter-associated local discomfort using a visual analogue scale. In a randomly assigned, crossover design, the effectiveness of the endoscopically (e) inserted ITO catheter was assessed by measuring the capillary blood gases, respiratory rate (RR), tidal volume (Vt) and minute ventilation (MV) after 1 h breathing room air without eITO and 1 h after eITO (flow: 3 l/min). MEASUREMENTS AND RESULTS: The eITO catheter was placed in all patients without complications and with only minimal discomfort in two patients (spontaneously reversible cough). Compared to breathing room air, capillary O2 pressure increased (from 54.7 +/- 9.4 to 82.8 +/- 21.8 mmHg) whereas Vt (from 458.7 +/- 86.8 to 358.3 +/- 75.1 ml) and MV (from 7.7 +/- 1.5 to 5.5 +/- 1.1 l/ min) decreased significantly (each p < 0.0001) with eITO in all patients. The capillary CO2 pressure and RR did not change. CONCLUSIONS: Acutely extubated patients in whom oxygen therapy is indicated may profit from eITO. This new technique works immediately and is thus an effective short-term intervention of potential value in the intensive care unit.

Bronchoscopy↗
PubMed1997

A new tongue advancement technique for sleep-disordered breathing: side effects and efficacy.

We examined the efficacy and the acceptance of an oral device (SnorEx) causing a forward displacement of the tongue for the treatment of sleep-disordered breathing (SDB). Twenty-three consecutive subjects with SDB were investigated. Noncompliance (NC) of use of the oral appliance was observed in 74% (17 of 23) of the subjects. NC patients were characterized by unacceptable local side effects of the prosthesis, lacking improvement of indicators of daytime well-being, and a missing reduction of the respiratory disturbance index (RDI). The device was tolerated without side effects in 26% (6 of 23) of the subjects. In these compliant (C) subjects the RDI, EDS, and snoring improved significantly (p < 0.05) compared with baseline values. After 6 mo using the device, five of the six C patients were still using it. We conclude that the high rate of noncompliance and the low efficacy of the SnorEx prosthesis preclude large-scale use of this treatment modality in patients with SDB and snoring since the local side effects are the principal cause of NC. No useful predictive parameter of treatment compliance or treatment success was found. Thus, this dental appliance should be prescribed only for selected patients failing other treatment modalities seen by an experienced sleep-disorders specialist.

Dental Prosthesis↗
PubMed1997

[Optical stimulation method (Snore-Stop) and tongue retainer (Snore-Master) without relevance in therapy of obstructive sleep apnea and snoring].

Recently intra- und extraoral devices are increasingly used in order to treat obstructive sleep apnea and snoring. We examined the value of an optically stimulating system ("eye-cover", Snore-Stop) and a tongue-retainer (Snore-Master) as treatment of the obstructive sleep apnoe or snoring. In case of the eye-cover is a microphone integrated, which detects acoustic signals (e.g. snoring). After detection of snoring optical stimuli are generated in front of the eyes. This is intended to induce an arousal of the patient, without awaking him, causing a change of body position and this reduces the snoring or apneas. For the examination of the eye-cover in 26 patients (23 men, 55.6 +/- 10.3 years) polygraphic studies were performed while sleeping one night with the eye-cover and one night without, respectively. Visual analogue scales (VAS) were used in order to measure quality of life and sleep and the adverse effects of the device. To examine the tongue-retainer 14 patients (13 men, aged 52.9 +/- 11.8 years) were measured polygraphically. Again the subjective scores were assessed using the VAS. The principle of the tongue-retainer is to create a hollow space in front of the teeth, in which the tongue is positioned. Fixation of the tongue in this ventral position is thought to enlarge the mesopharyngeal area in order to reduce the upper airway obstruction. For both devices the index of snoring, the apnea-hypopnea-index, the index of desaturation, the mean and minimal SaO2 and SaO2 < 90 % in % of the night did not change significantly. Furthermore the subjective perception of the patients concerning their quality of sleep and life did not change. Moreover, despite of an adequate adaptation-period the use of the tongue-retainer was associated with considerable adverse effects. Neither the eye-cover nor the tongue-retainer could improve the severity of obstructive sleep apnoe or snoring.

Adult↗
PubMed1996

[Satisfaction of cataract patients].

BACKGROUND: Most of the presentations concerning quality assurance following cataract surgery are based upon objective data, as it should be. But the success of an eye-clinic is not limited by such objective data, but on the contentment of the patients and the local colleagues, who direct the patients. Our aim in the following study is to find out, if there is a correlation between objective data and the contentment of cataract-patients. MATERIAL AND METHODS: 101 non-selected patients were asked about their contentment following cataract surgery and lens implantation. They were asked twice; first immediately after surgery and second two months after surgery. The subjective data of the patients were compared with objective data. RESULTS: 99% of the patients were content with the surgery, but only 88% were content with their visual acuity. There was no correlation between contentment of the patients and visual acuity. 13% of the patients reached a vision below 0.2. All but one said to have a good or moderate vision. 16% claimed to have poor or very poor vision, they all had a vision between 0.2 and 1.0. CONCLUSIONS: The ophthalmic surgeon must not be satisfied by his own good surgical results. In addition, he has to take care of the contentment of his patients. But it is even more dangerous, if the surgeon is proud because of his many content patients. Even if the patients are satisfied, he has to take care, if he really deserves the thanks of them.

Adult↗
PubMed1996

A school-based clinic for elementary schools in Phoenix, Arizona.

A community hospital, a school district, and a private pediatrician's office collaborated to ensure all children enrolled in five elementary schools had access to health care services. The school nurse at each school identified children needing health care services and obtained parental consent. The school nurse referred children to a nurse practitioner who visited one school each day. School nurses and space in the nurse's office were provided by the school district. The hospital provided a nurse practitioner as well as pharmacy, radiology, laboratory, and emergency department services. The pediatrician as medical director for the program provided vision, training, and community connections, and served as collaborating physician for the nurse practitioner.

Ambulatory Care Facilities↗
PubMed1995

Platelet aggregation inhibiting and anticoagulant effects of oligoamines, XXX: Absorption, organ distribution, and excretion of the oligoamine (+)-(S,S)-1,4-bis-[4-(3-iodo-4-methoxyphenyl)-butylamino]-butane-2,3-di ol and its metabolites.

The pharmacokinetic behaviour of the 131-iodine-labelled title compound 3* and its metabolites in mice was investigated. A two phase, 1st order elimination profile was observed. The second phase is very slow leaving about 35% of radioactivity in the mice even 100 h after i.v. injection, because of high affinity to liver and spleen, caused by strong binding of oligoamines to phospholipids of liver and blood cell membranes. The blood-brain-barrier is not passed. No deep compartments were observed. The doses necessary for antithrombotic effects in vivo were calculated from the blood levels to be 20.5-39.7 mumol/kg for a time interval of 1-6 h after administration.

Animals↗
PubMed1995

Distribution behaviour of 131-iodine labelled trans-N,N'-bis-(ethoxy-carbonyl)-N-[4-(3-iodo-4-methoxyphenyl)butyl]-N' -5- phenylpentyl)-1,4-cyclohexanedimethanamine.

The title compound 9, which is a prodrug, and its active metabolite 7 were labelled with 131I (7*/9*) to investigate their pharmacokinetic behaviour, including the distribution between stomach, gut, muscle, blood, lung, liver, kidney, adrenal gland, heart, and spleen. Four hours after oral administration of 7* to mice only 3% of the dose had been absorbed from the g.i. tract. After 24 h 54% of the radioactivity still is found the gut, predominantly in the small intestine. These results explain why 7, which is a potent antiplatelet drug in vitro, shows no antithrombotic effect in vivo. In contrast, the produg 9/9* is absorbed considerably, i.e. up to 50% in 4 h from the g.i. tract depending on the dose applied and the vehicle used. At doses in the micromolar range the absorption appears to be diffusion limited. The highest concentrations are found in the liver and the kidneys suggesting a first pass effect of 7 followed by renal excretion. From the blood levels achieved, the dose necessary for an antithrombotic effect has been calculated to be about 100 mg/kg. In summary, the N-ethoxycarbonyl derivatives of oligoamines appear to be suitable prodrugs for oral administration of oligoamines.

Animals↗
PubMed1995

[Increase in hypercapnia in exercise--an unloading strategy?].

BACKGROUND: Chronic hypercapnia seems to preserve the overloaded respiratory pump from manifest muscle failure. In order to get information about the regulation of the ventilation under exercise we investigated clinical stable hypercapnic patients. PATIENTS AND METHODS: Twenty-one patients (20 males, 53.7 +/- 13.2 years) with obesity-hypoventilation syndrome (8), chronic obstructive lung disease (4), scoliosis (3), myopathy (2) and post-Tbc (2) were examined. Ventilation parameters (fb, Vt, VO2), respiratory muscle strength (PImax, PEmax), arterial blood gases (pO2, pCO2), respiratory quotient (RQ) and lactate were measured at rest and at the end of 5 minutes of maximal bicycle exercise. The control group consisted of 10 healthy persons. RESULTS AND CONCLUSIONS: A significant augmentation of the pre-existing hypercapnia under exercise (reflecting hypoventilation in relation to the predicted value) was observed in all patients with chronically overloaded respiratory muscles. This mechanism seems to be wise because it protects the respiratory pump from failure.

Adult↗
PubMed1995

[Value of transtracheal oxygen insufflation in the weaning period after long-term ventilation].

BACKGROUND: In many cases, respiratory muscle failure is the reason for unsuccessful weaning attempts after long-term ventilation. Therapeutic measures must therefore be aimed at unloading the respiratory pump. In this present study we examined whether, in particular, the transtracheal O2-insufflation (TTO2) results in a change of breathing patterns and unloads the respiratory muscles. PATIENTS AND METHODS: We examined 6 patients (5 males, age 65.6 +/- 3.9 years, diagnosis: chronic obstructive lung disease), who received long-term mechanical ventilation in outward intensive care units. Baseline resting data (arterial blood gas analysis, the breathing frequency and the minute volume) were obtained with the patients breathing room air for 1 hour. After receiving TTO2 with a flow of 21/min for another 1-hour-period the measurements were repeated. RESULTS AND CONCLUSION: In our study we could show that the TTO2 leads to an impressive decrease in inspiratory work of breathing-relative to the minute ventilation by about 28%. Therefore TTO2 is of great importance in the weaning phase subsequent to prolonged mechanical ventilation due to the respiratory muscle failure.

Aged↗
PubMed1995

[Foreign body reaction after lens implantation. Correlation between visual acuity and density of giant cells].

In the early postoperative stage giant cells often appear on IOLs. Independent of this, a foreign-body reaction may start about 3 months after surgery from posterior synechia. Foreign-body reaction occur more frequently in diabetic patients or patients with glaucoma. In a prospective trial, we examined the surface of the IOLs from 115 patients with diabetes or glaucoma using specular microscopy. We compared the maximal density of the cells to visual acuity. One week and 1 month after surgery, the maximal density of giant cells was between 0 und 20/mm2; vision (median) was independent of the giant cell density in all groups between 20/25 and 20/30. Three months after surgery, the maximal density of giant cells was between 0 und 35/mm2; vision (median) was 20/25 in patients with no giant cells or cell densities up to 15/mm2. Seven patients had cell densities between 16 and 35/mm2; visual acuity (median) was 20/125. The difference was significance was (P < or = 0.05). Six months and 1 year later after surgery, the maximal density of giant cells was between 0 and 41/mm2; the vision (median) in patients with giant cell densities up to 15/mm2 was between 20/20 and 20/25. In five examinations the cell densities were found to be in the range of 16 to 40/mm2; visual acuity (median) was 20/80 in these cases. The difference is not significant (P < or = 0.05). A foreign-body reaction with more than 15 giant cells/mm2 is a rare complication of cataract surgery with lens implantation. Three months after surgery, this complication correlates with poor vision.

Aged↗
PubMed1995

[Epithelialization of porous biomaterials with isolated respiratory epithelial cells in vivo].

Extensive tracheal defects after prolonged assisted ventilation, trauma or large resections in tumor surgery are a challenge in plastic and reconstructive surgery. Defects which cannot be satisfactorily repaired reguine near of an alloplastic tracheal replacement. Previous experimental and clinical experiences in the development of an alloplastic tracheal prosthesis have demonstrated that the main cause for failure is the lack of an epithelial lining of luminal surfaces and inadequate biophysical properties of the prosthesis. With the use of a cell-seeding technique tested in vitro on biomaterials epithelialization of tracheal prostheses can be tested in vivo. In animal experiments isolated respiratory cells were seeded into implanted tubular prostheses of porous polyurethane or expanded polytetrafluorethylene. Light and scanning microscopic investigations then showed the tendency of epithelialization to occur on the luminal surfaces. Vigorous squamous epithelium cell layers that were single and (predominantly) multiple layers were found. Differentiated cilated or mucous cells were not detected in any case. The present results have shown that epithelialization of incorporated porous implants is possible. The realization of usable tracheal replacement for clinical practice must still be tested in further experiments.

Animals↗
PubMed1994

[Decompression of the optic nerve after fractures of the rhino-basal skull with computer-assisted surgery].

Referring to 22 cases of surgery after frontobasal fractures of different origin with loss of vision, the surgical procedure is discussed with special consideration of the approach, technique and timing of the operation. We conclude that the external rhinological approach through the ethmoid sinus is the best and easiest access in cases of loss of vision with verified fracture or haematoma. A number of patients were operated using CAS (Computer Assisted Surgery)-Systems, a CT-based tool for three-dimensional orientation. It proved to be very useful for the surgeon, saving time and reducing the risk of additional damage. According to our experience and the results of other authors we believe that surgical intervention should be performed as early as possible.

Blindness↗