Biomedical subjects

A Baumgartner

Publications and source records attributed to A Baumgartner.

At least 37 records · Page 2Linked to original sources

PubMed2001

Detection of aneuploidy in rodent and human sperm by multicolor FISH after chronic exposure to diazepam.

Aneuploidy induction in male germ cells of mice and men after chronic exposure to diazepam (DZ; CAS 439-14-5; Valium was assessed by multicolor fluorescence in situ hybridization (FISH). DZ, a widely administered sedative and muscle relaxant, was proposed to act as an aneugen by disturbing spindle function in various assay systems. Male mice were treated by oral intubation with 3mg/kg DZ once or daily for 14 consecutive days. At 22 days after the last treatment, epididymal sperm were collected from the caudae epididymes. Evaluation of aneuploid and diploid sperm (10,000 sperm per animal) was performed by multicolor FISH employing DNA probes specific for chromosomes X, Y, and 8 simultaneously. We found a significant increase in the frequency of disomy 8 in subchronically DZ-treated mice when compared to the concurrent solvent control group (2.4-fold; P<0.01), while no increase was detected for sex-chromosome hyperhaploidies. No effect was seen when mice were treated with a single dose (3mg/kg DZ). In a parallel human approach, two men were evaluated who chronically ingested >0.3mg/kg/d DZ for more than 6 months. Multicolor FISH was applied to human sperm probing for chromosomes X, Y, and 13. Frequencies for sperm with disomy 13, disomy X, and total sex-chromosomal disomies were found to be elevated among the two subjects after chronic DZ-exposure compared to control subjects. In conclusion, the results indicate that diazepam acts as an aneugen during meiosis in male spermatogenesis, both in mice and humans. The quantitative comparison indicates that humans may be at least 10 times more sensitive than mice for aneuploidy induction by DZ during male meiosis.

Adult↗

PubMed2001

Bone mineral density in pre-and post-menopausal women with affective disorder treated with long-term L-thyroxine augmentation.

BACKGROUND: Augmentation with TSH-suppressive L-thyroxine (T4) has been shown to improve the course of illness in otherwise refractory affective disorders. This collaborative study investigates whether T4 augmentation for a minimum of 12 months decreases bone mineral density (BMD) in 26 pre- and post-menopausal women with affective disorder. METHODS: We measured BMD at the femoral neck, Ward's triangle, trochanter and lumbar vertebrae (L1-L4) in 13 premenopausal and 13 postmenopausal women with affective disorder using dual energy X-ray absorptiometry. BMD was expressed as g/cm(2) and as a Z-score, calculated using bone density data from the international reference population standard. RESULTS: The Z-scores for the pre- and post-menopausal women were within the reference range of the age and sex matched population standard. BMD for the composite group also did not differ either from the population standard. BMD in the lumbar spine and hip did not differ significantly between the pre- and post-menopausal groups. However, there were a relatively high number of postmenopausal patients with BMDs one S.D. lower than the population standard. LIMITATIONS: This is a cross-sectional study with a relatively small sample size. CONCLUSIONS: The study demonstrates that T4 augmentation treatment does not reduce BMD to a clinically significant degree in many women with affective disorder. However, the resilience of bone structure to T4 treatment may vary with site and menopausal status. This study underscores the need for regular assessment of BMD during adjunctive thyroid treatments for affective disorder, especially in postmenopausal women.

Absorptiometry, Photon↗

PubMed2001

Effect of chemicals on the duration of male meiosis in mice detected with laser scanning cytometry.

Aneuploidy studies in sperm such as the sperm-FISH assay require a precise knowledge of the duration of spermatogenesis, especially of the meiotic stages. This is important in order to sample sperm from the epididymis at appropriate intervals after animal treatment. However, aneugens may delay the cell cycle. The progression from meiotic divisions to epididymal sperm was determined by labelling the last S-phase before meiosis with the thymidine analogue 5-bromo-2'-deoxyuridine (BrdU) and treating the animals 13 days later with the test chemicals. In a time frame of 20--24 days after treatment, BrdU-containing sperm were identified with a FITC-labelled anti-BrdU antibody and green fluorescent sperm were scored with a laser scanning cytometer (LSC). We studied the effects of the chemicals acrylamide, colchicine, diazepam, griseofulvin, taxol, thiobendazole, trichlorfon and vinblastine on the duration of meiotic divisions in male mice. Colchicine treatment prolonged the duration of meiotic divisions by about 48 h. On days 21 and 22, the frequencies of BrdU-labelled sperm in the colchicine group were 11.7 and 9.4%, respectively, while they were 28.4 and 30.6%, respectively, in the concurrent controls (P > 0.01). On day 24 after treatment, the frequency of labelled sperm in the colchicine group reached the control level. Etoposide treatment resulted in an elevation of BrdU-labelled sperm at 23 rather than 22 days. The other chemicals showed no significant effect of prolonging meiotic cell cycle progression. On the basis of the colchicine and etoposide data, it is suggested that the effect of a chemical on the meiotic cell cycle progression is determined first in order to chose the appropriate sperm sampling time to detect aneuploidy induction.

Animals↗

PubMed2000

Frequency of Cryptosporidium spp. as cause of human gastrointestinal disease in Switzerland and possible sources of infection.

Detection of Cryptosporidium parvum is not routinely done in laboratories of clinical microbiology and there is no obligation to communicate isolations of this pathogen to health authorities. For these reasons, frequency of cryptosporidiosis and sources of infection are only poorly known in Switzerland. To obtain more concise information in this field, feces from 5179 hospitalized and 1256 ambulatory patients with suspected gastrointestinal infections were screened for Cryptosporidium spp. over the period of one year in two laboratories. In toto, 13 patients with cryptosporidiosis were detected which results a frequency of 0.2%. Furthermore, it was shown by a projection that about 340 cases of cryptosporidiosis have to expected yearly in Switzerland, resulting an estimated morbidity of 4.85 cases per 100,000 persons. With regard to risk factors, the available patient data did not allow solid statistical conclusions. However, known risk factors such as immunosuppression, travelling abroad (33.3%) and contact to symptomatic persons were unquestionably demonstrated. Oysters, raw milk and cream from raw milk had to be strongly taken into consideration as food vehicles of transmission. Tap water from municipal nets has not to be considered as relevant source of sporadic infections. The obtained data indicate that cryptosporidiosis is a disease of low epidemiological significance in Switzerland. To a great extent, cryptosporidiosis could be prevented by best known measures of personal hygiene, avoiding certain raw food-stuffs and being aware of safe catering on travels.

Animals↗

PubMed2000

The hypothalamic-pituitary-thyroid axis in patients with schizophrenia.

Serum concentrations of thyroxine (T(4)), triiodothyronine (T(3)), reverse triiodothyronine (rT(3)) and thyrotropine (TSH) were measured in 31 acutely ill in-patients with schizophrenia before and after four weeks of treatment with the phenothiazine derivative perazine. The serum levels of all the above hormones were also determined in 19 schizophrenic patients in remission who were receiving no medication, 20 schizophrenic patients in remission taking neuroleptic drugs, and 24 patients with residual-type schizophrenia. The serum levels of T(4) of acutely ill schizophrenic patients were elevated, while those of T(3), rT(3) and TSH were normal. Their T(4) levels showed a positive correlation with the severity of illness and the degree of clinical response to neuroleptic treatment. There was a significant fall in serum concentrations of T(4) and rT(3) during four weeks of drug treatment and the decrease was significantly correlated to clinical response. No abnormalities in the serum concentrations of any of the hormones measured were found in schizophrenic patients in remission or in residual-type schizophrenia. In conclusion, our results indicate that the elevated serum levels of T(4) may be specific for acutely ill schizophrenic patients and that neuroleptic medication may affect thyroid hormone metabolism, this interaction being involved in the mechanism of action of these drugs.

Acute Disease↗

PubMed2000

Resolution-improved dual-beam and standard optical coherence tomography: a comparison.

BACKGROUND: The purpose of the study was to demonstrate the improved axial resolution and longitudinal stability of dual-beam optical coherence tomography (OCT) in comparison to conventional OCT setups used in commercially available OCT instruments. METHODS: The conventional OCT technique is based on an interferometric setup that is rather sensitive to axial eye motions. We have developed a special dual-beam OCT technique which eliminates the influence of axial eye motions. This is achieved by using the anterior corneal surface as the reference surface for the interferometric ranging. To improve the signal quality, the different wavefront curvatures of beams reflected at cornea and retina are matched by a diffractive optical element. To improve the axial resolution, a broadband synthesized light source with an effective bandwidth of 50 nm is used, and the group dispersion of the ocular media is compensated. Tomographic images were recorded in the fovea and the optic nerve head of healthy volunteers. For comparison purposes, approximately the same locations in the same eyes were imaged by a commercially available OCT instrument. RESULTS: Compared to the standard OCT technique, the dual-beam OCT images show considerably improved axial resolution. Especially in tomograms recorded at the fovea, dual-beam OCT resolves microstructural details that are not visible in the standard OCT images. Furthermore, the axial stability of dual-beam OCT enables the recording of exact geometrical contours of fundus layers. CONCLUSIONS: Dual-beam OCT is able to provide structural information on the ocular fundus that is not obtained with standard OCT. The long recording times of our instrument limit the transverse resolution to 100-150 microm at present.

Fovea Centralis↗

PubMed2000

Effects of tranylcypromine on thyroid hormone metabolism and concentrations in rat brain.

The effect of 14 days administration of the anti-depressant tranylcypromine (TCP) on iodothyronine deiodinase activities and the concentrations of thyroxine (T4) and triiodothyronine (T3) were investigated in homogenates of up to nine regions of the rat brain. The activity of the 5III deiodinase isoenzyme, which catalyses the inactivation of T3 to 3,3'-diiodothyronine (3,3'-T2), was enhanced in eight brain regions. However, the brain levels of T4 were completely unchanged and the T3 concentrations were significantly reduced in the frontal cortex only. Therefore, we also measured the T3 concentrations of three subcellular fractions (nuclei, synaptosomes and mitochondria) of six brain regions. TCP induced a significant reduction in T3 levels in the synaptosomes of the frontal cortex and significant increases in the mitochondrial T3 concentrations in the amygdala. The latter effect was replicated after 14 days administration of 5 mg/kg desipramine. No effects of either drug on nuclear concentrations of T3 were seen in any brain region. As the amygdala is critically involved in the affective coloring of sensory stimuli, the increase in T3 concentrations in the mitochondria of this brain region may be of relevance for the mechanism of action of anti-depressant drugs.

Amygdala↗

PubMed2000

Gene expression of receptors and enzymes involved in GABAergic and glutamatergic neurotransmission in the CNS of rats behaviourally dependent on ethanol.

The steady state levels of the messenger RNA (mRNA) of eight GABA(A) receptor subunits, five glutamate receptor subunits and seven enzymes involved in the synthesis of glutamate and GABA were measured in eight regions of rat brain in a recently developed animal model of 'behavioural dependence' on ethanol. 'Behavioural dependence' including loss of control was induced by offering the rats the choice between ethanol and water over a 9-month period (Group A). This group was compared with a group given the choice between ethanol and water for only 2 months (not yet 'behaviourally dependent', Group B), a group forced to consume ethanol as sole fluid over a 9-month period (also not 'behaviourally dependent', Group C) and ethanol-naive control rats (Group D). All groups were sacrificed 1 month after the ethanol was withdrawn. The mRNA concentrations of all eight GABA receptor subunits, four out of the five subunits of different glutamate receptors and those of seven enzymes involved in GABA and glutamate production were reduced almost exclusively in the parieto-occipital cortex in Groups A and B, but not Group C. These data suggest that the synthesis of glutamate and GABA and the activities of their respective neurons are selectively impaired in the parieto-occipital cortex in the groups having consumed ethanol in a free-choice design, in which its rewarding properties can better take effect than after forced administration. As the parieto-occipital cortex is believed to contain emotional memory structures, it may be hypothesized that the glutamatergic and GABAergic neuronal systems in this area are involved in the development of memory for reward from ethanol. However, they are not specifically associated with 'behavioural dependence'.

Animals↗

PubMed2000

Trichlorfon induces spindle disturbances in V79 cells and aneuploidy in male mouse germ cells.

In order to assess the effects of trichlorfon on cell division and on aneuploidy induction, we conducted an in vitro assay for spindle disturbances using V79 cells and an in vivo assay for aneuploidy induction in meiosis of male mice using multicolour fluorescence in situ hybridization (FISH) with epididymal sperm. In the in vitro assay, the chemical caused a concentration-dependent increase in the incidence of initial and full c-mitoses in the dose range 40-120 microg/ml trichlorfon. The mitotic index (MI) was decreased between 40 and 100 microg/ml trichlorfon, whereas at 120 microg/ml the MI was back to the control level, coinciding with the dramatic increase in c-mitoses. The results confirm that trichlorfon is a potent spindle poison in V79 cells. In the in vivo multicolour FISH assay, administration of trichlorfon to male mice at single doses of 200, 300 and 405 mg/kg caused a dose-dependent increase of the frequencies of disomic sperm (0.068, 0.074 and 0.134%, respectively) compared with the corresponding controls (0.046, 0.042 and 0.056%, respectively). The prevalence of X-X-8 and Y-Y-8 sperm suggests that trichlorfon affected chromosome segregation predominantly during the second meiotic division. Diploid sperm were not induced by trichlorfon treatment, indicating that no meiotic block occurred. It is concluded that trichlorfon is a potent spindle poison in V79 cells and induces aneuploidy in mouse spermatocytes during meiosis.

Aneuploidy↗

PubMed2000

1-Aminobenzotriazole inhibits acrylamide-induced dominant lethal effects in spermatids of male mice.

Acrylamide (AA) is a germ cell mutagen and induces clastogenic effects predominantly in spermatids of mice. The mechanism of AA clastogenicity has been a matter of dispute. Since the reactivity of AA with DNA is low but is high with proteins containing SH groups, it was suggested that protamine alkylation could be the mechansim of clastogenicity by AA in spermatids. This was substantiated by the observation that the time course of protamine alkylation and dominant lethal effects in spermatids of mice induced by AA was strictly parallel. Another suggestion was that AA may be metabolized by cytochrome P-450 to the epoxide glycidamide (GA), which is then the ultimate DNA-reactive clastogen. This suggestion was based on the similarity of the stage specificity pattern for dominant lethality and heritable translocation induction by AA and GA. To test this latter assumption, 1-aminobenzotriazole (ABT), an inhibitor of P-450 metabolism, was used in the present experiments. Male mice were pretreated with ABT (3x50 mg/kg) on three consecutive days followed by AA treatment (125 mg/kg) on day 4. Parallel groups of animals were treated with AA (125 mg/kg), ABT (3x50 mg/kg) or with the solvent double-distilled water. The experiment was repeated once with slightly varied mating parameters. The results of both experiments showed that ABT inhibited or significantly reduced the AA-induced dominant lethal effects. Thus, the present data support the hypothesis that the AA metabolite GA is the ultimate clastogen in mouse spermatids.

Acrylamide↗

PubMed2000

Effects of pharmacological and nonpharmacological treatments on thyroid hormone metabolism and concentrations in rat brain.

The activities of the 5'I-deiodinase (5'D-I), 5'II deiodinase (5'D-II) and 5III-deiodinase (5D-III) isoenzymes and tissue concentrations of thyroxine (T4) and triiodothyronine (T3) were measured in up to 10 regions of the rat brain after acute and subchronic nonpharmacological (sleep deprivation, 12 h fasting, 14 days' calorie-reduced diet) and pharmacological (ethanol, haloperidol, clozapine, lithium, carbamazepine, desipramine, fluoxetine, tranylcypromine, and mianserin) treatments. All of these treatments induced significant and sometimes dramatic changes in 5'D-II activities and tissue concentrations of thyroid hormones and, to a lesser extent, in 5D-III activity. The activity of 5'D-I remained unaffected. The results revealed a surprising specificity for each type of treatment in terms of the isoenzyme and hormone affected, the direction of the change, the brain region affected and the time of day. The changes in thyroid hormone concentrations frequently failed to correspond in any way to those in deiodinase activities and unexpected effects such as inhibition of both 5'D-II and 5D-III were seen, indicating that there may be additional pathways of iodothyronine metabolism in the CNS. In conclusion, particularly 5'D-II activity and thyroid hormone concentrations in the CNS are highly sensitive to many different kinds of influence that may induce changes in neuronal activity. However, these changes in deiodinase activities do not ensure stable tissue concentrations of T3, but were, on the contrary, in most cases accompanied by marked changes T3 levels in the tissue. The implications of these findings for the physiological role of thyroid hormones in the CNS are discussed.

Aging↗

PubMed1999

Gene expression of glucose transporters and glycolytic enzymes in the CNS of rats behaviorally dependent on ethanol.

The steady-state levels of messenger RNA (mRNA) of the glucose transporters 1 and 3 and the glycolytic enzymes hexokinase, phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase and pyruvate dehydrogenase were measured in up to seven brain regions of the rat in a recently developed animal model of 'behavioral dependence' on ethanol. Irreversible behavioral dependence, including loss of control, was induced by offering the rats the choice between ethanol and water over a 9-month period (Group A). This group was compared with a group given the choice between ethanol and water for only 2 months (not yet behaviorally dependent, Group B), a group forced to consume ethanol as sole fluid over a 9-month period (not behaviorally dependent, Group C) and ethanol-naive control rats. All groups were sacrificed 1 month after ethanol withdrawal. The mRNA concentrations of both neuronal glucose transporter 3 and the key glycolytic enzymes phosphofructokinase and pyruvate dehydrogenase were significantly reduced in the hippocampi of the rats behaviorally dependent on ethanol (Group A). No significant changes were seen in any of the remaining brain regions (e.g., cortical areas, limbic forebrain, amygdala, midbrain) in Group A, or in any brain area at all in Groups B and C. The results show that chronic consumption of ethanol in a free-choice situation may impair neuronal glucose uptake and glycolytic flux. This effect is manifested exclusively in the hippocampus and is specifically related to the development of behavioral dependence, since it was not found after forced administration of large amounts of ethanol (Group C).

Alcoholism↗

PubMed1999

Treatment of refractory chronic depression and dysthymia with high-dose thyroxine.

BACKGROUND: An 8-week open trial was conducted to investigate whether patients with treatment-resistant, chronic depression and/or dysthymia could profit from high-dose thyroxine (T4) augmentation. METHODS: Nine patients whose current depressive episode had lasted for a mean of 15.5 +/- 8.6 months (range: 2-30 months) received T4 in addition to their current medication. RESULTS: Two patients dropped out of the study owing to side effects. The remaining 7 patients received a final mean dose of T4 of 235 +/- 58 micrograms/day (range: 150-300 micrograms/day). Their scores on the Hamilton Depression Rating Scale had fallen from a mean of 21.1 +/- 4.1 before inclusion in the study to a mean of 8.0 +/- 2.8 at the end of the 8th week. Five patients were full responders, 1 a partial responder, and 1 a nonresponder. CONCLUSIONS: Augmentation with high-dose T4 proved to have an antidepressant effect in more than 50% of the previously treatment-resistant patients with chronic depression and/or dysthymia.

Adult↗

PubMed1999

Numerical and structural chromosomal abnormalities detected in human sperm with a combination of multicolor FISH assays.

A pair of multicolor FISH assays (X-Y-21 and A-M-16) was developed for human sperm to simultaneously measure sex ratios; aneuploidies involving chromosomes 1, 16, 21, X, and Y; meiotic diploidies; and structural aberrations involving chromosome 1p. Sex ratios in sperm were not significantly different from unity among healthy men. Baseline frequencies of disomic sperm for chromosomes 1, 8, and 21 were similar (6.7 per 10(4) sperm, 95% CI of 5.6-8.1), suggesting that among these three chromosomes, chromosome 21 was not especially prone to nondisjunction. Frequencies of disomy 16 sperm were significantly lower, however (3.5 per 10(4) sperm, 95% CI of 2.0-6.2; P < 0.02). The baseline frequencies of sperm disomy by FISH for chromosomes 16 and 21 were validated against aneuploidy data obtained by the hamster-egg technique for human sperm cytogenetics. The frequencies of X-X, Y-Y, X-Y ("Klinefelter") sperm and sex-null ("Turner") sperm were 5.5, 5.1, 5.5, and 7.8 per 10(4) sperm, respectively. For chromosomes 16 and 21, the frequencies of nullisomic and disomic sperm were similar, suggesting that gain and loss events occurred symmetrically. However, more gain than loss was reported for chromosomes 1, X, and Y. The frequency of MI and MII diploid sperm (with flagella) was approximately 12 per 10(4) (range 8.3-16.7 per 10(4) sperm). Based on flagella data, the frequency of somatic cells in the semen was estimated to be approximately 1.8 per 10(4) sperm. Loss or gain of a portion of chromosome-arm 1p occurred in 5.5 per 10(4) sperm, and the percentage of sperm carrying structural aberrations within the haploid genome as calculated from FISH (1.4%), was similar to that obtained with the hamster-egg technique. These complementary sperm FISH assays have promising applications in studies of chromosomally abnormal sperm after exposure to occupational, medical, and environmental toxicants.

Adult↗

PubMed1999

Extraction and quantification of thyroid hormones in selected regions and subcellular fractions of the rat brain.

There is increasing evidence of an involvement of thyroid hormones in numerous physiological processes of the adult vertebrate brain. However, the only valid method available for measuring triiodothyronine (T3) in brain tissue is time-consuming and not sufficiently sensitive to determine hormone concentrations in small, but physiologically important areas such as the amygdala and septum. We therefore developed a protocol for reliable measurement of the concentrations of thyroxine (T4) and T3 in brain tissue. This was achieved by combining a new method of extracting iodothyronines with highly sensitive, accurate and reproducible radioimmunoassays (RIAs) in order to be able to detect T4 and T3 in homogenates and even subcellular fractions (nuclear, synaptosomal and mitochondrial) in up to 11 regions of the rat brain. The iodothyronines were extracted from tissue samples by adding 100% methanol containing 1 mM PTU. Recoveries of 72.8 +/- 5.5% and 83.2 +/- 3.3% for T4 and T3, respectively, were obtained. The RIA detection thresholds were 10 fmol/g for T4 and 18 fmol/g for T3. Only 0.2% of the antibody for T4 cross-reacted with T3 and 0.95% reverse T3. T3 antibody (0.05%) reacted with T4 and 0.01% with 3,5-T2. The T4 concentrations in the homogenates of selected areas of the brain ranged between 1 and 4 pmol/g, whereas those of T3 ranged between 0.5 and 4 pmol/g. The T3 levels ranged between 190 and 470 fmol/mg protein, 38 and 110 fmol/g protein and 25 and 180 fmol/mg protein in the nuclei, synaptosomes and mitochondriae, respectively. In conclusion, the newly developed method enabled us to determine both T4 and T3 concentrations in homogenates and T3 in subcellular fractions of regions of the brain as small as the septum and amygdala.

Animals↗

PubMed1999

Fiberoptic intubation in 327 neurosurgical patients with lesions of the cervical spine.

In patients with lesions of the cervical spine, direct laryngoscopy for endotracheal intubation entails the risk of injuring the spinal cord. In an attempt to avoid this complication, the authors used flexible fiberoptic nasal intubation in a series of 327 patients with cervical lesions undergoing elective neurosurgical procedures. The nasal route was preferred for laryngeal intubation because it is easier than the oral route and a restraining collar or halo device does not impair the intubating maneuver. Bronchoscopic intubation was possible in all patients. In 12 patients (3.6%), anatomic abnormalities prevented transnasal insertion of the endotracheal tube, and transoral fiberoptic intubation was necessary. Endotracheal intubation was graded as slightly difficult in 85 patients (26%). The minimal peripheral oxygen saturation during intubation exceeded 90% in 289 patients (88%). In the other 38 patients, the mean O2 saturation was 84.2+/-4.3% (range, 72-89%). Intubation was well tolerated by all patients and none had recall of the procedure. Cervical stabilizers did not have to be removed for intubation in any patient. None of the patients had postoperative neurologic deficits attributable to the intubation procedure. The authors consider fiberoptic transnasal intubation to be a useful alternative to direct laryngoscopic tracheal intubation in patients undergoing elective surgical procedures on the cervical spine to avoid potential injury to the cervical spinal cord.

Adolescent↗

PubMed1998

Investigation of dispersion effects in ocular media by multiple wavelength partial coherence interferometry.

We report on quantitative measurements of group refractive indices and group dispersion in water and in human ocular media such as the cornea, the aqueous humor, the lens, artificial intraocular lenses, as well as a total value averaged over the media along the axial eye length of normal subjects and pseudophakic patients in vivo using dual beam partial coherence interferometry. Different optical thickness values due to the dispersion of the cornea are demonstrated using two spectrally displaced light sources. The displacement can be used to indirectly calculate the group dispersion of the human cornea in the spectral region between 810 nm and 860 nm. If the object under investigation is dispersive, resolution is limited due to a broadening of the detected signals. This broadening increases with group dispersion, i.e., the extent to which the group refractive index of the medium varies with wavelength and thickness of the tissue under investigation as well as with the spectral bandwidth of the light source. Measurements of the group dispersion in the cornea, lens and vitreous of pseudophakic and normal human eyes, show that the cornea and the lens are more dispersive than water-by a factor of about 5 and 2, respectively-in the investigated spectral region. The cornea is approximately threefold more dispersive than the human crystalline lens, the aqueous humor is less dispersive than water and the group dispersion of all ocular components together, averaged over the axial length of normal and pseudophakic eyes, was only slightly higher compared to that of water. Since the highly dispersive cornea and lens together have only a thickness of about one sixth of that of the axial eye length, it seems that their contribution to the group dispersive effect along the whole axial eye length is only small.

Aqueous Humor↗

PubMed1998

[High dosage thyroxine treatment in therapy and prevention refractory patients with affective psychoses].

The following review summarizes current knowledge on the treatment of therapy-resistant patients with affective disorders with supraphysiological doses of thyroxine (T4). Several groups have reported independently of each other that administration of 200-500 micrograms T4/day has excellent effects in 50-65% of patients a) with bipolar disorder, with or without, "rapid cycling" course, who were previously resistant to all prophylactic drugs and b) in the treatment of therapy-resistant depression. T4 is effective only in combination with an antidepressant or a prophylactic drug. Side effects are minimal, even when T4 is administered over several years. These results now justify to recommend high dose T4-augmentation as "last-resort" treatment also beyond research purposes, i.e. in psychiatric wards and in private practice. Recommendations for clinical applications are given and hypotheses on possible mechanisms underlying the efficacy of T4 treatment are discussed.

Bipolar Disorder↗