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Biomedical subjects

J Müller

Publications and source records attributed to J Müller.

At least 307 records · Page 17Linked to original sources
PubMed1997

Involvement of glibenclamide-sensitive potassium channels in vasorelaxation by cochlear nerve stimulation.

Rabbit aortic rings relaxed with an increase in cyclic guanosine monophosphate and cyclic adenosine monophosphate content in response to exposure to organ fluid of isolated cochleas of the guinea pig following field stimulation (50 Hz, 80 V, 0.2 ms). Relaxations were blocked by 30 microM N(G)-nitro-L-arginine methyl ester added to the vessel rings. This inhibitory effect was reversed by 3 mM L-arginine. Removal of the vascular endothelium also blocked the relaxation response. Glibenclamide attenuated vasorelaxation in a concentration-dependent manner. We conclude that cochlear nerve stimulation induces an endothelium-dependent vasorelaxation involving activation of adenosine triphosphate-sensitive potassium channels.

Animals↗
PubMed1997

Stapes surgery in osteogenesis imperfecta patients.

Osteogenesis imperfecta (OI), or the Van der Hoeve-de Kleyn syndrome, is a heterogeneous group of connective tissue disorders. The key features in this disease are bone fragility with a tendency to spontaneous fractures and deformations. The classical traid of symptoms involves a conductive and/or sensorineural hearing impairment together with a tendency to spontaneous bone fractures and blue sclerae. Between January 1988 and December 1994, ear surgery was performed on eight ears of six OI patients who presented with mixed hearing loss preoperatively. Pathological changes observed in the middle ear were atrophy and/or fractures of the stapedial crura in combination with thickening and fixation of the stapes footplate. Partial stapedectomy was performed in seven cases and a neo-window was created in the promontory of one patient when an overhanging facial canal obscured visualization of the oval window niche. Pre- and postoperative bone conduction thresholds did not differ in any of the patients. Postoperatively, mean values of the air-bone gap in the main speech frequency range were below 10 dB. Functional results following stapes surgery in patients with otosclerosis during the same time interval (n = 857) did not differ significantly. These data indicate that stapes surgery in OI patients can be performed with the same functional predictability as in otosclerosis patients, even though the underlying etiology is considerably different.

Adult↗
PubMed1997

[Temporary mechanical left heart support. Recovery of heart function in patients with end-stage idiopathic dilated cardiomyopathy].

BACKGROUND: Implantation of a mechanical cardiac support system (MCSS) in patients with idiopathic dilated cardiomyopathy (IDC) may improve cardiac function and allow explantation of the device. Our experience now includes 13 patients who have been "weaned" from MCSS and we report about the overall results of this treatment as well as the effects of ventricular unloading on cardiac function, anti-beta 1-adrenoceptor-autoantibody (A-beta 1-AAB) level and the degree of myocardial fibrosis. METHODS: 13 patients with non-ischemic IDC who had been admitted here in cardiogenic shock (CI < 1.61.min-1.m2, left ventricular ejection fraction [LVEF] < 16% and left ventricular internal diameter in diastole [LVIDd] > 68 mm) and who all tested positive for A-beta 1-AABs were implanted with an uni-(12 patients) or a biventricular (1 patient) mechanical assist device. Echocardiographic evaluation and A-beta 1-AAB-level-monitoring was routinely performed after implantation and explantation of the MCSS and the degree of myocardial fibrosis was assessed at the time of implantation and after explantation. RESULTS: During a mean duration of mechanical support of 236 +/- 201 days (range: 30 to 794 days), LV-EF improved to a mean of 46% and LVIDd decreased to a mean value of 56 mm in these 13 patients. A-beta 1-AABs decreased and disappeared 11.7 weeks after implantation of the device and did not reincrease thereafter. The highly pathologic degree of fibrosis at the time of implantation diminished to normal values about 1 year after explantation. One patient died of anesthesiologic complications and another patient shortly presented with a new episode of cardiac insufficiency 6 months after explantation. He was implanted again with an univentricular assist device was successfully transplanted 3 weeks later. Mean observation period of the remaining 11 patients now amounts to 12.6 +/- 9.77 (range: 3 to 26) months after explantation of the device--as of May, 31, 1997--with a cumulative observation period of 139 patient months. CONCLUSION: Temporary implantation of a MCSS may normalize cardiac function in selected patients with IDC. The striking degree of myocardial fibrosis can reduce to normal values after explantation of the device. A-beta 1-AABs disappear during ventricular unloading and do not increase thereafter. "Weaning" from mechanical device may constitute an alternative treatment to cardiac transplantation in selected patients.

Adult↗
PubMed1997

Epidemiology of invasive mycosis in ICU patients: a prospective multicenter study in 435 non-neutropenic patients. Paul-Ehrlich Society for Chemotherapy, Divisions of Mycology and Pneumonia Research.

OBJECTIVE: To determine the epidemiological and clinical significance of invasive fungal infections in non-neutropenic patients in intensive care who stay longer than 10 days on the intensive care unit (ICU). DESIGN: Prospective epidemiological multicenter study over a period of 11 months, based on strict clinical, bacteriological, serological and histological criteria. SETTING: Six surgical and two medical ICUs units in five university and two municipal hospitals. PATIENTS: 435 non-neutropenic patients from medical and surgical ICUs with an ICU stay of more than 10 days. MEASUREMENTS AND MAIN RESULTS: A new occurrence of invasive mycosis (3 sepsis/4 peritonitis/1 disseminated candidiasis), corresponding to the protocol conditions with onset after day 10 in the ICU, was detectable in 2.0% (95% confidence interval 0.85 to 3.8%) of the 409 patients who could be assessed. Candida species were identified as an infection-relevant pathogen in all cases. The most important risk factor for the development of an invasive mycosis was the onset of peritonitis by the day 11 in the ICU (odds ratio 11.3; p = 0.003). A fungal colonization was detected in 64% of patients (Candida species 56%, Aspergillus 4%, and other fungi). Six of 8 patients with an invasive mycosis died on the ICU; ICU mortality in patients with fungal colonization was 31% and in noncolonized patients 26%. Serological tests were not helpful clinically. The sensitivity was 88% for the Candida HAT (haemagglutination test) (threshold titer > 1:160), 100% for the Candida IFT (immunofluorescence test) (threshold titer > 1:80), and 50% for the Candida Antigen Test (Candtec Ramco, threshold titer > or = 1:8), and the specificity was 26, 6, and 73%, respectively. The specificity for the Aspergillus HAT (threshold titer > 1:10) was 29%. CONCLUSIONS: Invasive mycoses are rare in non-neutropenic ICU patients, even after a longer stay in the intensive care unit; fungal colonization, on the other hand, is frequently detectable. The mortality of invasive mycosis--even with systemic antimycotic therapy--was high; the mortality in patients with fungal colonization was not significantly increased compared to that in noncolonized patients. The serological test procedures, Candida HAT, Candida IFT, and the Candida Ramco Antigen Test, had a low specificity and were not helpful in diagnosing relevant invasive mycosis.

Adolescent↗
PubMed1997

Humoral rejection after heart transplantation: reliability of intramyocardial electrogram recordings (IMEG) and myocardial biopsy.

In recent years, as the importance of humoral-mediated rejection has increasingly become recognized, the fact that endomyocardial biopsies (BX) evaluated according to the criteria of the International Society for Heart and Lung Transplantation often produce false-negative results has become a matter of concern. To evaluate the reliability of measuring intramyocardial ECG amplitude (IMEG) and immunofluorescence evaluation (FITC-labeled anti-IgG/ IgM staining) of endomyocardial biopsies (IFM), heterotopic neck-heart transplantation (HTX) was performed on eight beagles previously sensitized through skin transplantations. After HTX, IMEG, echo, and donor-specific antibodies in serum (IgG, IgM) were determined daily and myocardial biopsies (IFM, BX) were performed once every 2 days. Accelerated (humoral) rejection occurred on the 5th (4th-5th) postoperative day and sensitivity of IMEG, IFM, and BX was 100%, 75%, and 12.5%, respectively. In each case rejection was recognized so early that it was possible to initiate therapy with "restitutio ad integrum". Our results show that, as opposed to endomyocardial biopsy (IFM, BX), IMEG diagnosis detected humoral-mediated rejection early and with high reliability.

Animals↗
PubMed1997

X-linked adrenal hypoplasia in a large Greenlandic family. Detection of a missense mutation (N4401) in the DAX-1 gene; implication for genetic counselling and carrier diagnosis.

X-linked congenital adrenal hypoplasia (AHC) is a developmental disorder of the human adrenal gland that results in profound hormonal deficiencies, which are lethal if untreated. Hypogonadotropic hypogonadism (HHG) is frequently associated with this disorder. The gene (DAX-1) responsible for the disease has recently been isolated. It encodes a protein with large similarity to members of the nuclear hormone receptor superfamily. Several different mutations in this gene have been found in patients suffering from AHC. We have identified a missense mutation (N440I) in three patients with AHC and HHG, all belonging to a large Greenlandic family. A total of 42 individuals has been tested for this mutation. We have diagnosed 10 women as carriers, and have excluded 22 women with a 25-50% risk from being carriers, emphasizing the rapid impact of molecular genetic techniques.

Adolescent↗
PubMed1997

Laparoscopic resection of high rectovaginal fistula with intracorporeal colorectal anastomosis and omentoplasty.

A 46-year-old Caucasian female underwent vaginal hysterectomy for myoma in another hospital and developed a high rectovaginal fistula 6 weeks later. A diverting-loop colostomy of the sigmoid colon was performed 2 months later. The patient was admitted to our service with persistent high rectovaginal fistula 6 months later. We resected the sigmoid colon and two-thirds of the rectum including the fistula tract using laparoscopic techniques. An intracorporeal anastomosis was accomplished using a double-stapling technique. An omental flap was mobilized and placed between the colorectal anastomosis and the vagina. Except for a subcutaneous wound infection at the former colostomy site, the postoperative course was uneventful. The patient was discharged at the 7th postoperative day and remained free of symptoms. We conclude that laparoscopic resection of high rectovaginal fistula with primary intracorporeal anastomosis is feasible and should be considered in selected cases as an alternative "minimal-invasive" approach to this disease.

Anastomosis, Surgical↗
PubMed1997

Heterogeneity of gonadoblastoma germ cells: similarities with immature germ cells, spermatogonia and testicular carcinoma in situ cells.

Gonadoblastoma is defined as a neoplasm containing nests of germ cells and cells resembling Sertoli cells or granulosa cells. Gonadoblastomas arise almost exclusively in dysgenetic gonads. They are associated with an increased risk of developing germ cell tumours. Testicular germ cell tumours in adults are preceded by carcinoma in situ cells, which are characterized by their morphology, by their immunohistochemical expression of placental-like alkaline phosphatase, the proto oncogene c-kit and/or epitopes for the monoclonal antibodies M2A, 43-9F and TRA-1-60, and by their aneuploid DNA content. In order to elucidate if gonadoblastomas are in situ neoplasms from the beginning, showing similarities with carcinoma in situ cells in otherwise normal testes, we investigated the germ cells in gonadoblastomas for their expression of the immunohistochemical markers of carcinoma in situ cells from six patients aged 8 1/2 months to 20 years and 4 months. In addition, the DNA content of the germ cells from five of the six patients was also determined by densitometric measurement on Feulgen stained specimens. The germ cell populations were heterogeneous both within the same patient and between the patients. Expression of the testicular carcinoma in situ markers was detected in specimens from all the patients and germ cells with an aneuploid DNA distribution pattern in accordance with testicular carcinoma in situ cells were detected. However, apparently normal immature germ cells were also present in four of the patients of whom two also had germ cells with a morphology similar to normal spermatogonia. Thus, gonadoblastoma is most likely an in situ germ cell neoplasia from the beginning. It seems probable that the germ cell tumours associated with gonadoblastomas originate from the carcinoma in situ cells inside the gonadoblastoma. Our findings of carcinoma in situ cells in gonadoblastomas from children support the theory that the cells arose prenatally.

Adolescent↗
PubMed1997

Effects of pulsatile flow on gas transfer of membrane oxygenator: MENOX EL-4000 and Gyro C1-E3 pulsatile mode.

It is acknowledged that pulsatile flow enhances the gas exchange performance of membrane oxygenators. However, the data for currently developed oxygenators are limited. In this study, the effect of pulsatile flow was assessed utilizing the MENOX EL-4000 oxygenator. The in vitro test was performed following the Association for the Advancement of Medical Instrumentation (AAMI) standards. Pulsatile flow was produced by the Gyro C1-E3 centrifugal pump with periodical changing of the impeller speed. In Study 1, the following 3 groups were created and examined: nonpulsatile flow, pulsatile flow of 40 bpm, and pulsatile flow of 60 bpm. The blood flow rate was maintained at 3 L/min, and the V/Q ratio was 1. In Study 2, four groups were examined, nonpulsatile flow with V/Q = 1, nonpulsatile with V/Q = 2, pulsatile with V/Q = 1, and pulsatile with V/Q = 2. The blood flow rate was maintained at 4 L/min, and the pulse frequency was set at 40 bpm. In study 1, although O2 transfer was not enhanced, CO2 transfer was significantly improved (40-50%) by pulsatile flow, regardless of pulse frequency. Study 2 demonstrated that pulsatile flow resulted in improved CO2 transfer as did higher ventilation (V/Q = 2). Furthermore, even after applying higher ventilation, the pulsatile mode enhanced CO2 transfer more than the nonpulsatile mode. It was considered that the pulsatile mode induced an active secondary flow and enhanced mixing effects, and consequently CO2 transfer was improved. In conclusion, the pulsatile flow significantly enhanced the CO2 transfer of the MENOX oxygenator. It is indicated that applying the pulsatile mode is a unique and effective method to improve the gas exchange performance for a current membrane oxygenator.

Analysis of Variance↗
PubMed1997

Control system modification of an electromechanical pulsatile total artificial heart.

A reliable control system is one of the most important characteristics of the electromechanical pulsatile total artificial heart (TAH). Obtaining an error-free procedure is essential for a successful in vivo implantation. To avoid any malfunction of the electrical control system, a modification of the previously designed controller was made to ensure stable pumping without the Hall effect sensor missensing. The installation position of the Hall effect sensor was changed from the top of the housing to the central piece with small magnets being installed in the stabilizer rods. The usage of the Hall effect sensor was chosen as an electrical switch. An in vitro one month running test of the TAH demonstrated adequate hydrodynamic performance with a completely error-free pumping characteristic. The total efficiency of the TAH was 12.6 +/- 1.4% at an 8 L/min outflow and 10.7 +/- 1.0% at a 6 L/min outflow condition.

Electricity↗
PubMed1997

Hypogonadism and endocrine metabolic disorders in Prader-Willi syndrome.

Disturbances of the hypothalamic-pituitary-gonadal axis are reviewed in patients with Prader-Willi syndrome, and a brief account is given of thyroid function, adrenal function and glucose metabolism in such patients. Cryptorchidism, hypoplastic external genitalia and delayed or incomplete pubertal development in most patients with Prader-Willi syndrome suggest dysfunction of the hypothalamic-pituitary-gonadal axis. Decreased levels of gonadotrophins, consistent with hypogonadotrophic hypogonadism, have been found in some patients, whereas others appear to have hypergonadotrophic hypogonadism secondary to cryptorchidism and its treatment. Gonadal function is normal in a small number of patients with the syndrome. Although most clinicians agree that cryptorchidism should be corrected in early childhood, in practice the surgery is often not performed. In addition, most patients do not receive sex hormone replacement therapy. It is therefore suggested that more aggressive endocrine treatment strategies for hypogonadism are warranted in both children and adults with Prader-Willi syndrome. Both thyroid function and adrenal function appear to be normal in most patients, and glucose metabolism is similar to that in normal obese individuals.

Adolescent↗
PubMed1997

Effects of growth hormone treatment on growth and body composition in Prader-Willi syndrome: a preliminary report. The Swedish National Growth Hormone Advisory Group.

A controlled, randomized study was conducted to assess the effect of growth hormone (GH) treatment on growth, body composition and behaviour in prepubertal children (3-12 years of age) with Prader-Willi syndrome. GH treatment was given to one group of 15 patients (group A) at a dose of 0.1 IU/kg/day for 2 years. The second group (group B; n = 12) was not treated for the first year and was then given GH at a dose of 0.2 IU/kg/day for the second year. All patients had low 24-hour levels of GH and insulin-like growth factor I before GH treatment. Height velocity SDS increased from -1.9 +/- 2.0 to 6.0 +/- 3.2 during the first year of GH treatment in group A, and from -1.4 +/- 1.2 to 10.1 +/- 3.9 in the second year of the study in group B. When GH treatment was stopped, height velocity declined dramatically. Height SDS followed a similar pattern. GH treatment reduced the percentage body fat and increased the muscle area of the thigh. Isometric muscle strength was also increased. In addition, GH treatment appeared to have psychological and behavioural benefits, which were reversed after cessation of treatment. It was concluded that GH treatment improves growth, body composition and behaviour in children with Prader-Willi syndrome.

Body Height↗
PubMed1997

Scarring folliculitis in the ectrodactyly-ectodermal dysplasia-clefting syndrome. Histologic, scanning electron-microscopic and biophysical studies of hair.

Several clinical syndromes are characterized by ectodermal dysplasia (ED) in association with clefting of the lip and/or palate. In these syndromes, alopecia is primarily due to abnormalities of the hair shaft associated with increased hair fragility. Scalp dermatitis is yet another peculiar finding, primarily seen in the ankyloblepharon-ED-clefting (AEC) syndrome. We report on a 16-year-old patient with ectrodactyly-ED-clefting (EEC) syndrome, who exhibited a scarring alopecia due to deep folliculitis. On scanning electron microscopy, irregular torsion and longitudinal grooving of the hair shaft (pili torti et canaliculi) were observed. Quantitative determinations of the elastic and viscous parameters of hair demonstrated a normal viscosity but a significantly reduced hair elasticity, indicating either an abnormal composition or a disordered arrangement of microfibrils within the apparently normal keratin matrix. In contrast to the erosive scalp dermatitis of early onset in the AEC syndrome, alopecia in this case of EEC syndrome demonstrated follicular scarring with onset during puberty. We question a possible role of the anatomical hair abnormality in the pathogenesis of chronic deep folliculitis in this and clinically related syndromes.

Adolescent↗
PubMed1997

Serum inhibin B in healthy pubertal and adolescent boys: relation to age, stage of puberty, and follicle-stimulating hormone, luteinizing hormone, testosterone, and estradiol levels.

Inhibin B levels were measured in serum from 400 healthy Danish prepubertal, pubertal, and adolescent males, aged 6-20 yr, in a cross-sectional study using a recently developed immunoassay that is specific for inhibin B, the physiologically important inhibin form in men. In addition, serum levels of FSH, LH, testosterone, and estradiol levels were measured. Serum levels of inhibin B, FSH, LH, testosterone, and estradiol all increased significantly between stages I and II of puberty. From stage II of puberty the inhibin B level was relatively constant, whereas the FSH level continued to increase between stages II and III. From stage III of puberty the FSH level was also relatively constant, although there was a nonsignificant trend of slightly decreased FSH levels at pubertal stage V compared to stage IV. The levels of serum LH, testosterone, and estradiol increased progressively throughout puberty. In prepubertal boys younger than 9 yr, there were no correlation between inhibin B and the other three hormones. In prepubertal boys older than 9 yr, a significant positive correlation was observed between inhibin B and FSH, LH, and testosterone. However, at this pubertal stage, each hormone correlated strongly with age, and when the effect of age was taken into account, only the partial correlation between inhibin B and LH/testosterone remained statistically significant. At stage II of puberty, the positive partial correlation between inhibin B and LH/testosterone was still present. At stage III of puberty, an negative partial correlation between inhibin B and FSH, LH, and estradiol was present, whereas no correlation between inhibin B and testosterone could be observed from stage III onward. The negative correlation between inhibin B and FSH persisted from stage III of puberty onward, whereas the correlation between inhibin B and LH and between inhibin B and estradiol was nonsignificant at stages IV and V of puberty. In conclusion, in boys, serum inhibin B levels increase early in puberty; by pubertal stage II the adult level of inhibin B has been reached. The correlation of inhibin B to FSH, LH, and testosterone changes during pubertal development. Early puberty is characterized by a positive correlation between inhibin B and LH/testosterone, but no correlation to FSH. Late puberty (from stage III) is characterized by a negative correlation between inhibin B and FSH (which is maintained in adult men), a diminishing negative correlation between inhibin B and LH, and no correlation between inhibin B and testosterone, suggesting that developmental and maturational processes in the hypothalamic-pituitary-gonadal axis take place, leading to the establishment of the closed loop feedback regulation system operating in adult men. The positive correlation between inhibin B and LH/ testosterone at the time when serum inhibin B levels rise early in puberty suggests that Leydig cell factors may play an important role in the maturation and stimulation of Sertoli cells in the beginning of pubertal development.

Adolescent↗
PubMed1997

Free insulin-like growth factor I serum levels in 1430 healthy children and adults, and its diagnostic value in patients suspected of growth hormone deficiency.

Serum levels of total insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) reflect endogenous GH secretion in healthy children, which makes them good diagnostic markers for screening of GH deficiency (GHD) in short children, although some controversy still exists. Only a minor fraction of the total IGF-I circulates in its free form, which is believed to be the biologically active form. However, our knowledge of the clinical or physiological value of determination of free IGF-I in serum is limited at present. In adults, the diagnostic value of total IGF-I and IGFBP-3 determinations in patients suspected of GHD has only been reported in a few studies, whereas no previous reports on the diagnostic value of free IGF-I levels in adults suspected of GHD exist. Serum levels of free IGF-I were determined in 1430 healthy children, adolescents, and adults by a newly developed, commercially available immunoradiometric assay (Diagnostic Systems Laboratories) to establish valid normative data for this analysis. We studied the diagnostic value of free IGF-I in relation to total IGF-I and IGFBP-3 determinations in adults who were suspected of GHD. A GH provocative test, using oral clonidine, was performed in 108 adult patients who had previously been treated with GH in childhood. In healthy subjects, free IGF-I levels increased during childhood, with the highest mean values during puberty. After puberty, a subsequent decline in serum levels of free IGF-I was apparent. We found, unmeasurable free IGF-I values in 34 of the prepubertal children (3.3%). All individuals over 8 yr of age had measurable free IGF-I levels that amounted to approximately 1% of the total IGF-I concentrations. Free IGF-I levels were below--2 SD in 56 of 79 GHD patients (sensitivity, 71%) and above--2 SD in 24 of 29 patients with a normal GH response (specificity, 83%). Multiple linear regression analysis demonstrated that free IGF-I was significantly dependent on peak GH levels, duration of the disease, and number of other pituitary axes affected. We conclude that free IGF-I serum levels increase during childhood with a peak in puberty, whereafter free IGF-I levels return to prepubertal levels. Three percent of healthy prepubertal children had unmeasurable free IGF-I levels using this assay. We found that determination of the free IGF-I serum concentration may predict the outcome of a GH provocative test in adults suspected of GHD, but that a single determination of free IGF-I offered no significant advantage compared to determination of total IGF-I or IGFBP-3 serum levels.

Adolescent↗