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Biomedical subjects

G Hofmann

Publications and source records attributed to G Hofmann.

At least 19 recordsLinked to original sources
PubMed1995

[Receptive musical aptitude using a binaural frequency discrimination test].

Musical aptitude is the most important precondition for any applicant taking up studies at a music conservatory. Thus, the applicants are tested and assessed very thoroughly by experienced music teachers. To support these subjective results by objective data a procedure was developed allowing to test both the examinee's frequency and octave discrimination capacity in a simple way. In a 1-Hz cycle the frequencies f1 and f2 are directed mutually to the right and left ear, respectively, at a defined sound level. Then the examinee is asked to syntonize e.g. frequency equality f1 = f2 (or f1 = 2 x f2). It can be shown that there is a direct correlation between the amount of deviation from nominal frequency and subjective assessment of musicality.

Adult↗
PubMed1995

[Problems in differential diagnosis and therapy of intracardiac space-occupying lesions--myxoma and thrombus].

The total removal of the myxoma under extracorporeal circulation from the origin maintains the optimal surgical treatment. Differentiation between myxoma and thromboses is a problem of preoperative diagnostics. Both tumors show unspecific symptoms. Therefore echocardiography and angiography are required as diagnostic tools. Between 1984 and 1991, 14 patients were cured from intracardiac tumors in the Clinic for Cardiovascular Surgery of the University of Leipzig. Problems in the sensitivity and security of the preoperative diagnostics and certain aspects of the surgical treatment will be discussed.

Adult↗
PubMed1992

MRI of the knee joint with a 3-D gradient echo sequence. Equivalent to diagnostic arthroscopy?

Three-dimensional (3-D) gradient echo sequences offer the advantage of volume imaging within a few minutes scanning time and creating thin contiguous slices. An optimized sequence (FISP 3D 40) was evaluated for its potential to detect lesions of the menisci, cruciate ligaments, and articular cartilage in 80 patients compared to arthroscopy as the standard. Magnetic resonance imaging showed a sensitivity of 97.9%, a specificity of 97.3%, and an accuracy of 97.5% for meniscal lesions, and a sensitivity of 100%, a specificity of 97.1%, and an accuracy of 97.5% for lesions of the cruciate ligaments. Based upon morphological criteria normal cartilage was identified in 91.5%, but fibrillation of different depths (grades 1-3) was poorly recognized. All full-thickness defects (grade 4) were recognized. Measurement of mean signal intensity (95% confidence intervals) was more useful to discriminate normal from abnormal cartilage (grades 1-3). This method promises the capability to detect early stages of oestoarthritis in future. The present results show MRI of the knee joint with a 3-D fast imaging technique to be a noninvasive alternative to diagnostic arthroscopy.

Adolescent↗
PubMed1991

Expression of measles virus RNA in peripheral blood mononuclear cells of patients with measles, SSPE, and autoimmune diseases.

In order to characterize measles virus (MV) infection in peripheral blood mononuclear cells (PBMCs), RNA was isolated from PBMCs after PHA-stimulation for 72 hr of 9 patients with acute measles, 16 patients with subacute sclerosing panencephalitis (SSPE), 13 patients with various autoimmune diseases, and 16 healthy control donors. The RNA obtained was screened for the presence of MV N (nucleocapsid) gene specific transcripts of either positive or negative orientation in a S1 nuclease protection assay. The sensitivity of this assay allowed us to detect one infected cell in 20,000 PBMCs or 0.1 to 0.05 copies of MV-specific RNA per cell. Using single-stranded DNA or RNA probes expression of MV genomic RNA of negative polarity could be detected in only one case of acute measles and one healthy control donor. Conversely, N-specific transcripts of positive polarity, indicating active transcription, could only be detected in patients with acute measles. In addition, in infected PBMCs and in a persistently MV-infected B cell line positive stranded N-specific transcripts containing leader usually present at very low frequency have been found in relatively increased amounts in comparison with transcripts lacking leader. Whereas the ratio of these RNA species during lytic infection with MV in Vero cells is about 1:50, the ratio found here ranges from 1:3 to 1:10. This altered ratio indicates a specific regulation of MV specific transcription in cells of lymphoid origin that has not been found in any other cell system analyzed.

Animals↗
PubMed1991

High-resolution endovaginal ultrasonography of the endometrium: a noninvasive test for endometrial adequacy.

Endovaginal sonography of the endometrium demonstrates characteristic findings throughout the menstrual cycle. To correlate these findings with histologic criteria for normal endometrial development, we compared endometrial biopsies with ultrasonographic findings. Nineteen cycles were monitored in 18 women with ovarian failure whose endometrial cycles were induced exogenously by sequential transdermal 17 beta-estradiol (E2) and intramuscular progesterone. These subjects underwent ultrasonography of the endometrium prior to the day of progesterone initiation (luteal day +1) and continuing throughout the mid-secretory phase. On luteal day +1, ultrasonography characteristically demonstrated a multilayered endometrium consisting of a hyperechoic perimeter (endometrial-myometrial interface), a hypoechoic inner layer, and a hyperechoic midline (luminal interface). By luteal day +7, a gradual increase in echogenicity of the inner layer was detected, while the inner myometrium remained hypoechoic. Eleven of 19 cycles demonstrated a completely hyperechoic endometrium on luteal day +7 and also demonstrated normal stromal development on endometrial biopsies. Three patients who had endometrial biopsies consistent with their chronological development failed to demonstrate a hyperechoic endometrium by luteal day +7. All five biopsies that were histologically out of phase were detected by ultrasonography. Thus, ultrasonography demonstrated a sensitivity of 100% and a specificity of 62% for the detection of histologically normal endometrial development. Endometrial thickness could not be used to discriminate between biopsies that were normal (13 +/- 1.0 mm) and those out of phase (13.8 +/- 1.8 mm). Endometrial histology demonstrated asynchrony of glands and stroma in nine cases in which ultrasonography correlated with stromal, but not with glandular dating, suggesting that the increased echogenicity may reflect stromal edema.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Biometry of the anterior chamber of the eye in Nd:YAG laser iridectomy].

In a prospective clinical study covering 41 eyes (28 patients) with narrow-angle glaucoma the central and peripheral anterior chamber depths were determined biomicroscopically before and after Nd:YAG laser iridectomy. In 29 eyes the central anterior chamber depth was also measured by ultrasonography. In contrast to the increase in central anterior chamber depth, which was only slight, the increase in the peripheral anterior chamber depth was statistically significant (P less than 0.01).

Anterior Chamber↗
PubMed1990

[Clinical aspects of the detection of early arthrosis. Degenerative changes of the menisci of the knee joint].

In a series of 420 persons the knee and hip joints were examined anamnestically and clinically. From this series, 146 persons were selected for further examination of one knee joint by means of magnetic resonance imaging (MRI) on a 1.5 Tesla Magnetom; there was a wide range of indications. Only four MRIs showed no pathological findings in the cruciate ligaments, cartilage surfaces, or menisci. Fifty-one menisci showed grade 3 degenerative changes. In 29 cases (57%), isolated horizontal tears were found, in 1 case (2%) an isolated vertical tear, and in 3 cases (6%) combined horizontal and vertical tears. The correlation of the degenerative changes in the medial meniscus and age was significant (P = 0.01). There was no correlation between the degenerative changes of the medial meniscus and femoral or tibial changes of the cartilage. In this series, there was no significant connection between degenerative changes of the medial meniscus and the previously accepted clinical symptomatology.

Adult↗
PubMed1990

[Possibilities for early detection of arthroses using imaging procedures].

Today early detection of osteoarthrosis (OA) must imply the recognition of initial changes of articular cartilage before radiological signs appear. A noninvasive imaging technique must meet the demands of imaging the articular cartilage layer with high contrast and surface irregularities (fibrillation) and changes within the substance. This can only be achieved by magnetic resonance imaging (MRI) with optimized conditions (3D-gradient echo sequence). In 80 patients, 62% of them without radiological signs of OA, articular cartilage of the knee joint was prospectively (70 patients) and retrospectively (10 patients) investigated with MRI and compared with the arthroscopic findings. Normal cartilage could be distinguished from pathological conditions with a specificity of more than 90% when evaluating surface morphology, signal homogeneity and, above all, signal intensity (40 patients). Full-thickness defects were identified in all cases. Cartilage fibrillation of differing depths (grades 1-3) could not be differentiated with a sufficient degree of reliability and requires a more subtle evaluation method by means of improved software. Thus, the noninvasive recognition of early pathological changes of articular cartilage in patients without radiological signs of OA has become possible.

Adult↗
PubMed1989

Effects of clomiphene citrate on episodic luteinizing hormone secretion throughout the menstrual cycle.

Pituitary luteinizing hormone secretory dynamics (pulse frequency and amplitude) were evaluated in eight normal women administered clomiphene citrate or placebo. After 5 days of treatment clomiphene citrate was found to increase mean luteinizing hormone secretion by increasing the amount of pituitary luteinizing hormone released per pulse. No change in pituitary luteinizing hormone interpulse interval was found in the follicular phase of the cycle, although a faster pulse frequency in the luteal phase was found after clomiphene citrate when compared with placebo. No differences were found in the luteal phase (pulse frequency, amplitude, and mean luteinizing hormone level) after clomiphene citrate versus placebo in the volunteers. These data suggest that the principal mechanism of action of clomiphene citrate is an increase in the concentration of hypothalamic gonadotropin releasing hormone into the hypothalamic-pituitary portal circulation, with a resultant increase in pituitary luteinizing hormone secretion.

Adult↗
PubMed1987

[Complementary acoustic EEG control while recording early acoustically evoked potentials].

An easily performed method for the additional acoustical assessment of the EEG quality by the investigator during recording of human brainstem potentials is presented. By means of feedback of the audibly transposed "noiselike" EEG voltage to the opposite ear of the examined subject (instead of the usual masking noise) the subject can perceive self-produced disturbances (muscle activities) and minimize them for the period of examination. An example shows how this additional rejection of artifacts via "biofeedback" can effectively support methods that are already in use.

Audiometry, Evoked Response↗
PubMed1986

[Is YAG laser iridotomy suitable for the prevention of glaucoma attacks?].

In a prospective clinical trial comprising 41 eyes with narrow-angle glaucoma, the patency of YAG laser iridotomy was checked using a rapidly-acting parasympatholytic drug. YAG laser iridotomy was performed after an acute attack of angle-closure glaucoma, in either the affected or the fellow eye. Tropicamide mydriasis had no effect on IOP either in the patient group or in the control group of ten normotensive eyes.

Glaucoma↗
PubMed1986

Reproduction of postprandial neurotensin plasma levels by intravenous neurotensin and the effect of neurotensin on exocrine pancreatic secretion in humans.

A fatty meal releases neurotensin immunoreactivity from the small bowel in humans and dogs, and an infusion of synthetic neurotensin elicits exocrine pancreatic secretion in these species. It is not clear, however, which amount of exogenous neurotensin will reproduce endogenous neurotensin plasma levels as postprandial neurotensin immunoreactivity is composed of several fragments of neurotensin without biologic activity in addition to intact neurotensin. In order to clarify this question, we infused 1.25, 2.5, 5.0 and 7.5 pmol/kg/min synthetic Gln4-neurotensin in four volunteers, determined neurotensin plasma levels with a radioimmunoassay recognizing only intact neurotensin, and collected duodenal contents for estimation of pancreatic secretion. On another day, we determined neurotensin plasma levels after a fatty meal. Reverse-phase high-pressure liquid chromatography (HPLC) was performed on postprandial plasma samples. We found a stimulatory action of neurotensin on pancreatic secretion of volume enzymes and bicarbonate beginning with 1.25 pmol/kg/min neurotensin. The neurotensin plasma level after infusion of this dose of synthetic neurotensin was 69 pg/ml; after the meal, maximal neurotensin plasma concentration was 50 pg/ml (basal neurotensin plasma levels in both investigations were subtracted). HPLC indicated the presence of the tridecapeptide known to be the active molecular form of neurotensin in postprandial plasma. These results suggested that neurotensin plays a role as an endocrine hormone in the postprandial regulation of exocrine pancreatic secretion in humans.

Dietary Fats↗
PubMed1985

[Organic psychosyndrome with and without lithium therapy].

After two years of treatment with Lithium-salts we did not find organic brain syndrome. Lithium treated patients have improved in thinking, concentration, the short-time memory, attention and conception. Control group did not have this improvement. Lithium-treated patients seemed to have more self-confidence, more flexibility and are able to master problems in a better way. Control group patients were more dependent on their moods and therefore did not improve in efficiency.

Affective Disorders, Psychotic↗