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Biomedical subjects

G Geyer

Publications and source records attributed to G Geyer.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Ionomer cement as bone substitute in the middle ear of the rabbit].

Ionomer-based cements are obtained by the reaction of an aluminum-fluoro-silicate glass with a polyalcenoic acid. During setting and hardening the cement bonds closely with adjacent hard tissue. The previous implantation of this material in the baboon tibia has held great promise as a possible use in bone replacement. In the present study the cement was tested concerning its biocompatibility and biostability in the middle ears of 64 rabbits. Viscid cement paste was inserted into the epitympanic space of each animal. A preformed cement strut was then placed to serve as a columella between the eardrum and stapes footplate. During a subsequent interval of 28 days up to 2 years middle ear specimens were evaluated under a surgical microscope, following which histologic sections were studied under light microscopic conditions. Findings demonstrated that after insertion of freshly mixed cement a firm adhesion to bone developed that proved to be biocompatible and biostable over time. After 28 days the preformed and fully hardened implants were overgrown by a delicate mucosa normally present in the middle ear. No evidence for any rejection of the implants could be found. The experience available to date indicates that ionomer cement is biocompatible and biostable, easy to handle and workable without splintering. With appropriate use it represents a useful implant material in surgery of the head and neck.

Animals↗
PubMed1997

[Ionomer cement prostheses in reconstructive middle ear surgery].

Animal experiments with microbiologic examinations and studies in cell cultures have shown that ionomer cement is a biocompatible and biostable bone replacement material in the head and neck region. Clinical and functional results of its use in the human middle ear have proven to be satisfactory during a maximal period of 2.5 years observation. The present trial was continued in order to determine the long-term behavior of ionomer cement (Ionos partial and total ossicles) after reconstruction of the ossicular chain. The ossicular chain was reconstructed in 343 cases and included various losses of one or more of the ossicles (i.e., incus, incus and malleus, incus and stapes superstructure, and malleus, incus and stapes superstructure). Follow-up extended over a maximum period of 5.5 years. Patients were examined under a surgical microscope and a pure-tone audiogram was performed at regular intervals. Clinical and audiological results were obtained 3 months postoperatively in all reconstructive procedures performed (partial and total ossicular replacement prostheses). These were mainly stable but revision surgery was necessary in 9% of the cases. In 5% the prosthesis was displaced and in 3% the prosthesis had partially migrated through the eardrum. Complete rejection of the implants was observed in the course of infections in 1% of the cases. Ionomer cement as a bone replacement material was found to have all required criteria for its use in the middle ear (biocompatibility, biostability, stable audiologic results and easy workability). These findings show that ionomer cement can be recommended in all cases of ossicular reconstruction.

Adolescent↗
PubMed1997

Performance of ionomeric cement (Ionocem) in the reconstruction of the posterior meatal wall after curative middle-ear surgery.

The hybrid bone-substitute ionomeric cement is suitable for restoring the original anatomy of the posterior canal wall. During a four-year period the posterior meatal wall was rebuilt with ionomeric cement in 74 patients. The canal wall was totally rebuilt in 38 patients, two-thirds rebuilt in 22 cases, and one-third rebuilt in 14 cases. On the meatal side, the canal wall was covered by a musculo-periosteal (Palva) flap. In the majority of cases, the drum was closed with (cartilage)-perichondrium. Revisions were performed in 27 patients (due partially to cholesteatoma, and/or poor visualization of radical mastoidectomy cavities). The ears were non-infected at the time of operation. Permanent epithelialization of the bone replacement material was achieved in 57 cases, with secondary closure of a cutaneous defect of the meatal wall being required in six cases. The auditory canal wall had to be removed in 17 patients owing to deficient soft-tissue coverage, persistent inflammation, and/or partial adhesive processes with development of cholesteatoma. In terms of surgical technique, utilization of the material over a follow-up period of maximally seven years proved it to be a sophisticated procedure for reconstructing the meatal wall. Despite the finesse of the surgical technique employed, the overall failure rate of 31 per cent was inadmissibly high. Implantation of the material should therefore be restricted to middle ears with permanent ventilation and no trace of infection.

Adult↗
PubMed1997

[Prevalence and significance of carbohydrate craving in Austria].

Among disorders of appetite and eating frequent craving of carbohydrate containing snacks between meals is well known. Excessive carbohydrate consumption causes increased caloric intake and may lead to overweight and risks of obesity regarding metabolism and vascular remodelling. Up to now prevalence and consequences of that disorder have never been studied in the Austrian population. Hence we investigated by questionnaires and interviews eating habits in samples of 1058 women and 942 men of the Austrian population. Evaluation showed that carbohydrate craving is a more or less serious problem for about 30% of Austrians. Women, especially those with overweight, were affected more frequently than men. In the whole population sample investigated there was a seasonal variation with a tendency to increased carbohydrate craving in fall and winter. This was, however, not significant for overweight women, they probably eat their snacks over the whole year. A subgroup of males reported craving of snacks containing sausage or meat instead of carbohydrate. Craving of carbohydrate is considered the consequence of a decrease of serotonin in appetite regulating neurons and centers of the brain. Treatment of craving by drugs inhibiting the re-uptake of serotonin into afferant neurons is discussed. Medication of this type is, however, hampered by cardiovascular side effects observed with fenfluramines.

Adolescent↗
PubMed1995

[Effect of dexfenfluramine on eating behavior and body weight of obese patients: results of a field study of Isomeride in Austrian general practice].

In a multicenter study by 243 practicing physicians in Austria 819 severely obese subjects of both sexes without overt disease were encouraged to keep a calorie-restricted diet to reduce weight. After a run-in period of more than two weeks of dieting patients started taking 15 mg dexfenfluramine (Isomeride) twice daily for three month. While their weight was fairly stable during the run-in period progressive weight loss occurred during taking dexfenfluramine due to obvious changes in eating habits and appetite allowing to keep the reducing diet more strictly. Females lost 7.7 +/- 3.9 kg while obese men lost 9.32 +/- 4.6 kg. Laboratory tests obtained before starting dexfenfluramine and after 3 months at termination of medication showed blood glucose, cholesterol, LDL and triglycerides to decrease while HDL-cholesterol increased moderately. Dexfenfluramine was well tolerated by the majority of patients. Side effects such as fatigue, sedation, flatulence or diarrhea occurred in only 7.9% of the probands initially and dropped to 2.1% during the third month of the medication. It is concluded that Dexfenfluramine modifies eating habits and appetite thus making weight reducing diets easier acceptable and resulting in weight loss. It is suggested that Dexfenfluramine has a role in treatment regimes for morbid and refractory obesity.

Adult↗
PubMed1994

Closure of the petrous apex of the temporal bone with ionomeric cement following translabyrinthine removal of an acoustic neuroma.

When performing translabyrinthine surgery for acoustic neuroma, the surgeon opens the cerebrospinal fluid space. To prevent the development of post-operative meningitis, the surgical defect should be closed reliably in a watertight fashion. To date, this has been done with success in 12 patients altogether using a self-curing bone cement (ionomeric cement). During follow-up for a maximum of three years there has been no evidence of cerebrospinal fluid leaks.

Bone Cements↗
PubMed1994

[Restoration of sound transmission in the middle ear by reconstruction of the ossicular chain in its physiologic position. Results of incus reconstruction with ionomer cement].

We report the use of an ionomeric based bone substitute to reconstruct the ossicles in their normal position. To reconstruct small defects of the incudo-stapedial joint, this bone replacement material is applied to the long process of the incus and the head of the stapes. After setting and hardening a stable contact to the adjacent bone is formed. The audiological results after reconstruction of small incus defects with ionomeric cement are discussed in comparison to stapedectomy and tympanoplasty.

Adult↗
PubMed1994

[Lateral pharyngeal diverticulum as a cause of superior laryngeal nerve neuralgia].

Superior laryngeal neuralgia was first described at the turn of the century by Avellis. In absence of accompanying disease in the organs adjacent to the nerve, idiopathic neuralgia is the most likely diagnosis. A 63-year-old man presented with left superior laryngeal neuralgia. Endoscopy revealed no pathological findings. Barium examination of the pharynx applying a modified Valsalva's manoeuvre revealed a small (0.5 cm) lateral pharyngeal diverticulum. 21 months after successful surgical removal the patient remains symptom-free. In the case of a 65-year old woman with left superior laryngeal neuralgia, barium examination revealed a lateral pharyngeal diverticulum at the same position between the hyoid-bone and the upper margin of the thyroid cartilage. The symptoms disappeared spontaneously. This is the first case of this particular kind of lateral pharyngeal diverticulum described in the literature. The explanation for the obstinate superior laryngeal neuralgia caused by such a small diverticulum must be sought in its immediate neighborhood to the superior laryngeal nerve.

Aged↗
PubMed1994

The non ergot D2-dopamine agonist CV 205-502 decreases growth hormone concentrations in acromegalic patients.

It was the aim of this study to test for a possible effect of the new non ergot dopamine agonist CV 205-502 on plasma growth hormone (GH) concentrations in acromegaly. 10 acromegalic patients received a single oral dose of 150 micrograms CV 205-502 after an overnight fast. As a control group 7 acromegalic patients undertook the same procedure without receiving any drug. Blood samples were drawn hourly up to 7 hours thereafter for determination of GH. Plasma growth hormone concentrations decreased by 48.8 +/- 8.7%. The nadir was observed 3 hours after CV 205-502 was administered and GH concentrations remained suppressed throughout the 7 hours of the test period. In contrast GH plasma concentrations in the control group remained stable. We conclude that acute administration of CV 205-502 suppresses GH secretion in acromegalic patients and thus could serve as an alternative therapy in acromegaly.

Acromegaly↗
PubMed1993

Bone mineral density and parameters of bone metabolism in patients with acromegaly.

To assess the effect of chronically elevated plasma growth hormone (GH) levels on bone metabolism and bone mineral density (BMD), 16 patients (10 females and 6 males) with a mean age of 49.1 +/- 13.2 years (range 33-68) with active acromegaly were studied and compared to a control group of 16 sex- and age-matched subjects. BMD of the lumbar spine and two different sites of the proximal femur were measured by dual-energy x-ray absorptiometry (Norland XR-26). In the acromegalic patients the mean plasma GH concentration was 30.1 +/- 11.1 micrograms/liter, and the mean plasma somatomedin C (SMC) concentration was 6.5 +/- 1.5 U/liter. Mean serum osteocalcin (OC) levels (14.3 +/- 1.1 versus 7.2 +/- 0.4 ng/ml, p < 0.001) as well as the urinary hydroxyproline excretion (OHP; 8.8 +/- 1.4 versus 2.7 +/- 0.3 mg, p < 0.0001) were significantly higher in the acromegalic patients than in the control subjects. In the acromegalic patients BMD was significantly elevated in the two examined regions of the proximal femur, that is, the femoral neck (1.06 +/- 0.05 versus 0.86 +/- 0.03 g/cm2, p < 0.05) and Ward's triangle (0.92 +/- 0.06 versus 0.76 +/- 0.03 g/cm2, p < 0.02), whereas the BMD of the lumbar spine was not significantly different from that of control subjects. Among the patients with acromegaly a significant positive correlation between serum OC concentrations, on the one hand, and urinary OHP excretion (r = 0.7, p < 0.004) as well as BMD in the proximal femur (r = 0.64, p < 0.007), on the other hand, could be observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1993

Ionomer-based bone substitute in otologic surgery.

During post-set hardening the self-curing bone substitute Ionocem develops a solid bond with the adjacent bony tissue, leaving no empty spaces. The fully matured material can be fixed to bone with freshly mixed cement or it may be used as a blank, e.g. an ossicular implant (Ionos ossicle). After insertion of 945 alloplastic middle ear prostheses over a period of 4.5 years, the take-rate was 94%. In some patients revision surgery became necessary, in 50% of cases because of prosthesis dislocation. A granular version of the cement (Ionogran) was implanted in 46 ears for obliteration of mastoid cavities and showed complete mucosal overgrowth within a maximal period of 3 months. Posterior canal wall reconstruction with the self-curing bone substitute was done in 74 patients, with revisions required in 12 cases because of persistent epithelial deficits in the external ear canal or epitympanic retraction. Overall results showed that the ionomer-based cement was a useful substitute for bone in reconstructive otologic surgery.

Animals↗
PubMed1993

[Ionomer cement in cochlear implant surgery].

Ionomer-based cement is a new bone replacement material. After promising results have been obtained with this material in middle ear and skull base surgery as well as in plastic reconstructive surgery, this material can be used to fix a cochlear implant system (internal receiver as well as the electrode) to the temporal bone. This material is formed via a reaction of a glass powder with a polycarboxylic acid. The cement has a manipulation period of about 5 minutes. After setting, the cement is well tolerated by tissue and has the additional advantage of being biocompatible and permanently stable in a biological environment. The cement and the acid are commercially available as a two-component capsulated system. In cochlear implant surgery this material is used to achieve a stable attachment of the internal receiver to the temporal bone. Displacement and damaging of the internal receiver and the electrode are prevented.

Cochlear Implants↗
PubMed1991

[Treatment of prolactinoma with a new dopamine agonist].

Eleven patients (6 men, 5 women, mean age 42 [25-65] years) with prolactinomas were treated for 4-16 months with a new dopamine agonist (CV 205-502), at a daily dose of between 0.075 and 0.45 mg. All patients had previously undergone surgery and/or been treated with bromocriptine or lisuride, but had not tolerated this therapy well, and/or had not shown sufficient suppression of serum prolactin levels. Baseline prolactin levels were between 149 and 4120 ng/ml. During treatment, levels fell significantly in all patients, to between 2.0 and 683 ng/ml, and to within the reference range in five patients. In seven patients, the adenoma size decreased by 10 to greater than 50%. Adverse reactions were less frequent and less marked than with the prior therapy. The new dopamine agonist is an alternative treatment for prolactinomas where other therapies have been unsuccessful.

Adult↗
PubMed1991

Tetracosactrin vs. methylprednisolone in the prevention of emesis in patients receiving FEC regimen for breast cancer.

0.5 mg tetracosactrin is considered to be equivalent to 40 mg methylprednisolone with regard to the induced cortisol secretion. 97 female breast cancer patients who received their first two FEC courses (epirubicin 50-75 mg/m2, 5-fluorouracil 500 mg/m2, cyclophosphamide 500 mg/m2) entered this randomised crossover study (76 had previously received an adjuvant treatment); tetracosactrin was administered intramuscularly and methylprednisolone intravenously immediately before chemotherapy administration. The tolerability was evaluated using a diary card during 5 days and patients were asked for their preference at the end of the two cycles. There was no difference either for vomiting (dry heaves were included) or nausea between the two treatments (the analysis was performed on day 1, the worse day of days 2 and 3 and the worse day of days 4 and 5). At day 1, 49% of the patients experienced no or mild nausea after tetracosactrin and 62% after methylprednisolone (not significant) (first period analysis); a complete control of vomiting (including dry heaves) was observed in 49% of the patients after tetracosactrin and 53% after methylprednisolone (not significant). No difference was observed between patients with or without previous chemotherapy. However, slightly more patients preferred tetracosactrin (P = 0.048).

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Medroxyprogesterone acetate lowers plasma corticotropin and cortisol but does not suppress anterior pituitary responsiveness to human corticotropin releasing factor.

The endocrine action of medroxyprogesterone acetate (MPA) has been claimed to be of a glucocorticoid-like nature. Upon clinical observation, MPA has been shown to improve life quality and overall well-being in patients with advanced breast cancer, renal carcinoma, prostatic carcinoma, and uterine adenocarcinoma. The authors have evaluated MPA endocrine action by the administration of human corticotropin releasing factor (hCRF) in a 90-minute assay in 15 patients with advanced breast cancer or renal cell carcinoma both, before the initiation of oral high-dose MPA treatment (1000 mg MPA) as well as after at least 10 days of therapy. The curves for corticotropin, beta-endorphin, and cortisol responses to hCRF of tumor patients who were tested before the initiation of MPA treatment were parallel to the curves of a healthy control group of probands tested under equal conditions, although at significantly higher respective hormone levels. In patients with malignant disorders assayed after MPA administration, both basal and peak hormone levels were found to be comparable with values obtained in healthy controls. In conclusion, MPA appeared to act at a suprapituitary level since pituitary responsiveness to hCRF was preserved under MPA treatment. Moreover, it appeared that MPA brought the hormonal stress state found in patients with malignant tumors back to normal.

Administration, Oral↗