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K Mann

Publications and source records attributed to K Mann.

At least 19 recordsLinked to original sources
PubMed2005

Validity of wave-front reconstruction and propagation of ultrabroadband pulses measured with a Hartmann-Shack sensor.

Wave-front reconstruction for ultrabroadband laser pulses is verified by use of a Hartmann-Shack sensor. We estimate the accuracy of numerical wave-front propagation by comparing numerical with experimental results and verify that wave fronts of ultrabroadband laser pulses from a hollow fiber can be propagated correctly by a single polychromatic wave-front measurement to a place where detection is not practicable, e.g., inside a vacuum chamber or laser focus.

Journal Article↗
PubMed2005

Endoscopic treatment of large primary adrenal tumours.

BACKGROUND: Endoscopic adrenalectomy has become the treatment of choice for small benign adrenal tumours but should not be used for malignant lesions. It is debatable whether large and therefore potentially malignant primary adrenal tumours should be removed by minimally invasive techniques. METHODS: Three hundred and eighty primary adrenal tumours in 368 patients (142 male and 226 female; mean(s.d.) age 48.9(14.4) years) were excised by laparoscopic or retroperitoneoscopic adrenalectomy. Adrenal neoplasias exceeded 6 cm in diameter (range 6-13 cm) in 33 patients (18 male and 15 female; age 42.6(14.2) years). RESULTS: There were no deaths. Patients with large tumours had an increased conversion rate (P = 0.039), longer operating time (P < 0.001) and greater intraoperative blood loss (P = 0.007) than those with smaller lesions, but a similar overall morbidity rate (P = 0.207). Six malignant tumours were identified (diameter 4-10 cm; four phaeochromocytomas and two adrenocortical carcinomas). Local recurrence developed in two patients and distant metastasis occurred in all six patients with malignant lesions. CONCLUSION: Endocopic adrenalectomy perfomed by an experienced surgeon should be the treatment of choice for tumours exceeding 6 cm in diameter.

Adolescent↗
PubMed2005

[The NMDA receptor system: genetic risk factor for alcoholism].

Alcohol dependence is one of the most common addictive diseases and known to be in part genetically transmitted, based on an oligogenic background in which each gene involved contributes only little to the resulting phenotype. Besides influencing other signal transduction mechanisms, alcohol specifically inhibits the NMDA signaling cascade, which mediates the excitatory effects of glutamate in the brain. Target molecules, sensitive to ethanol, include the NMDA receptors as well as downstream molecules of the glutamatergic system, glutamate transporters, and associated regulatory proteins. Adaptive processes of the glutamatergic system during chronic alcohol consumption may play a major role for later development of reward symptoms. Candidate gene studies, including association studies and animal models, are powerful and sensitive for detecting oligogenic effects and thus important to alcoholism research.

Alcoholism↗
PubMed2005

Improved drug delivery to cancer cells: a method using magnetoliposomes that target epidermal growth factor receptors.

The toxin delivery system described herein would allow for the selective killing of tumor cells overexpressing the epidermal growth factor receptor (EGFR). Tumor cells often overexpress EGFR, because it allows the cells to divide more quickly. Past delivery systems targeting this receptor have been ineffective due to a lack of specificity that results in harm to surrounding tissue and damage to organs such as the liver. The technique presented here is different, because it presents the possibility of delivering toxin only to the tumor area and almost exclusively to the tumor cells. Delivery is localized to the tumor tissue through the use of EGF conjugated magnetoliposomes. These are liposomes that have magnets imbedded in their bilayer, allowing for selective heating and release of a drug when the magnetoliposome is under an oscillating magnetic field. To create an additional level of specificity, the delivery system will consist of two EGF-bound components that must interact within the endosome of a cell for the toxin to be released. If a tumor cell overexpresses EGFR by 5-fold, then each of its endosomes will have 5 times more receptors than those of a normal cell. Therefore, the tumor cell's endosome has a 5 times greater chance of containing one EGF-bound component and a 25 times greater chance of containing both components. Since both components are necessary for toxin release, the tumor cells will receive 25 times more toxin than the normal cells. Theoretically, it is possible to produce a three or four component system that would deliver 125 or 625 times more toxin to the tumor cells.

Drug Delivery Systems↗
PubMed2005

Effects of a combination of rhGH and metformin on adiponectin levels in patients with metabolic syndrome.

Adiponectin is a recently discovered adipocytokine that correlates negatively with body mass index and body fat. In patients with GH deficiency, treatment with recombinant human growth hormone (rhGH) reduces body fat mass and thus may also have a favorable effect in patients with metabolic syndrome, and would also be expected to increase adiponectin levels. However, due to its diabetogenic effect, rhGH treatment also bears an increased risk for the development of type 2 diabetes mellitus. We conducted a 18-month randomized, double-blind, placebo-controlled study to assess the effect of rhGH in combination with metformin (MGH) in 14 obese men (7 MGH; 7 Metformin+Placebo, 54 +/- 2 years, BMI 33.0 +/- 1.2 kg/m(2)) with mildly elevated fasting plasma glucose (FPG) at screening (6.1-8.0 mmol/l). All patients received metformin (850 mg twice daily) for treatment of type 2 diabetes mellitus/impaired glucose tolerance, either alone or in combination with rhGH (daily dose 9.5 mug/kg body weight). Glucose disposal rate (GDR) was measured using the euglycemic hyperinsulinemic clamp technique, and body composition was measured by DEXA at 0 and 18 months. After 18 months, the mean adiponectin concentration increased by 32 +/- 11 % (p = 0.018) in the MGH group and did not change in the MP group (- 10 +/- 13 %; p = n. s.). The difference in relative changes in adiponectin levels between the two groups after 18 months was statistically significant (p = 0.026). Improvement in insulin sensitivity (GDR) correlated positively with adiponectin levels (r = 0.73; p = 0.004). In conclusion, the additional administration of rhGH increased adiponectin levels in patients with metabolic syndrome, indicating its potential role in adiponectin-associated insulin sensitivity alterations.

Adiponectin↗
PubMed2005

Effects of estrogen replacement therapy on bone and glucose metabolism in a male with congenital aromatase deficiency.

Little is known about the impact of estrogen replacement therapy for bone formation, glucose metabolism and hormonal parameters on males with aromatase deficiency. Transdermal estrogen (TE) replacement was initiated at 100 microg/week in months 0-3, 50 microg/week in months 3-6, 25 microg/week in months 6-12, 75 microg/week in months 12-24, and 25 microg/week in months 24-36 to substitute for the deficiency in a 27-year-old homozygous male with a mutation on the CYP19 gene. Estradiol levels increased from<10 at baseline to 45, 12, 27 and 17 pg/ml (normal range 10-50) after 6, 12, 24 and 36 months, and inversely correlated to LH and FSH levels. Testosterone levels changed from 31.2 nmol/l at baseline to 3.8, 22.1, 7.1 and 22.0 nmol/l (9.5-30) after 6, 12, 24 and 36 months, respectively, and correlated closely to basal and stimulated LH and FSH levels at 100 microg GnRH. Bone maturation progressed, and metacarpal and phalangeal epiphysis closed after 12 months. Spongiosa-hydroxyapatite of the radius assessed by quantitative computed tomography changed from 52 to 83, 51, 69 and 71 mg/cm3 (120-160); bone mineral density of the lumbar spine assessed by dual energy X-ray-absorptiometry (normal value>1.150) increased from 0.971 (T-Score -2.24) to 1.043 (-1.64), 1.065 (-1.46), 1.128 (-0.93) g/cm2 and 1.021 (-1.82) after 6, 12, 24 and 36 months of TE, respectively. Osteocalcin as a bone formation parameter and aminoterminal collagen type I telopeptide as a bone resorption parameter increased during high-dose estrogen supplementation, and then decreased during the lower doses. Lipoprotein (a) increased from 20 mg/dl at baseline to 60 and 62 mg/dl after 6 and 12 months, and then decreased to 24 and 25 mg/dl after 24 and 36 months, respectively, while total cholesterol, HDL, LDL and triglycerides did not change. AUC glucose decreased continuously after oral glucose load, and HOMA IR reached its lowest value the 75 microg weekly estradiol dose. This study confirms the role of estrogens in achieving bone mineralization and maturation in human males. Additionally, estradiol has dual negative feedback sites that on the hypothalamus to decrease GnRH pulse frequency, and on the pituitary to decrease responsiveness to GnRH. The improvement in glucose metabolism after estrogen replacement therapy suggests a probable role of sex steroids in insulin sensitivity. The optimal weekly dose of transdermal estrogen replacement for normalizing estrogen levels and maintain bone mass in adult males with aromatase deficiency may be 50-75 microg spread over two doses.

Adult↗
PubMed2005

Neuroimaging of gender differences in alcohol dependence: are women more vulnerable?

BACKGROUND: Alcoholic brain damage has been demonstrated in numerous studies using neuropathology and brain imaging techniques. However, gender differences were addressed only in a few studies. Recent research has shown that development, course, and consequences of alcohol dependence may differ between female and male patients. Our investigation was built upon earlier research where we hypothesized that women develop alcoholic brain damage more readily than men do. To further compare the impact of alcohol dependence between men and women, we examined brain atrophy in female and male alcoholics by means of computed tomography (CT). METHODS: The study group consisted of a total of 158 subjects (76 women: 42 patients, 34 healthy controls; 82 age-matched men: 34 patients, 48 healthy controls). All patients had a DSM-IV and ICD-10 diagnosis of alcohol dependence. CT with digital volumetry was performed twice in patients (at the beginning and end of the 6-week inpatient treatment program) and once in controls. RESULTS: Patients of both genders had consumed alcohol very heavily. Although the average alcohol consumption in the year before the study was significantly lower in female alcoholics, this gender difference disappeared when controlled for weight. However, women had a significantly shorter duration of alcohol dependence. Despite this fact, both genders developed brain atrophy to a comparable extent. Brain atrophy was reversible in part after 6 weeks of treatment; it did not reach the level in the control groups. CONCLUSIONS: Gender-specific differences in the onset of alcohol dependence were confirmed. This is in line with the telescoping effect, where a later onset and a more rapid development of dependence in women were described. Under the assumption of a gradual development of consequential organ damage, brain atrophy seems to develop faster in women. As shown in other organs (i.e., heart, muscle, liver), this may confirm a higher vulnerability to alcohol among women.

Adult↗
PubMed2005

Development and clinical impact of thyroglobulin antibodies in patients with differentiated thyroid carcinoma during the first 3 years after thyroidectomy.

OBJECTIVE AND DESIGN: Cross-sectional studies have reported an increased prevalence of circulating thyroglobulin autoantibodies (TgAbs) in patients with differentiated thyroid carcinoma (DTC). With the advent of more sensitive assays, a longitudinal study monitoring the development of TgAb levels after ablative therapy was warranted. METHODS: One hundred and twelve consecutive patients with follicular cell-derived thyroid cancer were followed for 3 years. All patients had been thyroidectomized and received, on average, two radioiodine therapies. Residual tissue was quantified scintigraphically by 131I 24-h uptake. TgAb and thyroglobulin (Tg) serum levels were determined with a sensitive direct radioligand assay and an IRMA respectively. RESULTS: The prevalence of TgAbs at the initial examination was 29% (median 130 U/ml). During follow-up, TgAb levels rose transiently in one-tenth of the patients, but the prevalence of demonstrable TgAbs decreased to < 10% after 3 years. The median serum half-life of TgAbs in treated DTC patients was 10 weeks. At initial examination (when all patients still had residual thyroid tissue and 17 had metastases), rising TgAb levels were correlated with the inability to detect Tg in 4, 30 and 73% of the patients, when initial TgAbs were < 6, 6-50 or > 50 U/ml respectively. While the Tg recovery test was valid for all patients, an in vitro dilution assay with TgAb serum reduced Tg values by up to 32%. CONCLUSIONS: The development and course of TgAbs in DTC patients cannot be predicted by initial or residual tumour volume, TgAb or Tg levels. The presence of TgAbs, even in low concentrations, may cause Tg underestimation despite valid recovery tests in DTC patients.

Adolescent↗
PubMed2004

[Metformin, an efficacious drug in the treatment of polycystic ovary syndrome].

BACKGROUND AND OBJECTIVE: Polycystic ovary syndrome (PCOS), with an incidence of 5% in women of reproductive age, is defined as the presence of oligo- or amenorrhea in combination with hyperandrogenism. Most patients also suffer from impaired insulin action (insulin resistance). PCOS thus resembles the metabolic syndrome (type 2 diabetes mellitus, hypertension, lipid disorders, atherosclerosis). International studies showed a beneficial effect of metformin treatment on biochemical and reproductive parameters in PCOS. The aim of our study is the evaluation of metformin treatment in a German PCOS sample. PATIENTS AND METHODS: 103 PCOS women (age 18-40) were treated, according to their body weight, with either 1000 mg or 1700 mg metformin per day after assessment of insulin resistance. Clinical features as well as endocrine and metabolic parameters were recorded at baseline and at 1, 6, and 12 months of treatment. Additionally, baseline data were compared with those of 98 control subjects (age 18-38). RESULTS: PCOS women showed significantly higher body mass index, body fat mass and androgen levels, as well as an impaired glucose- and insulin metabolism compared to controls. Metformin treatment ameliorated acne (36% to 4%), hirsutism-score (11.2 to 9.7) and restarted normal menstrual cycles in 66.7% of PCOS-women. Sixteen of 48 patients with unfulfilled wish to conceive became pregnant during therapy. Metformin restored menses in all previously amenorrheic women. Comparing post-metformin versus baseline levels, HOMA-IR (4.6 to 2.3), AUC-I (379 to 225) and 2-h glucose (117 to 90 mg/dl) decreased significantly. Furthermore, metformin decreased testosterone (2.9 to 1.8 nmol/l), free androgen index (9.1 to 5.3) and dehydroepiandrosterone levels (5.1 to 3.9 mg/l). CONCLUSION: Metformin improves significantly hyperandrogenism and insulin resistance in PCOS patients and appears to be an efficacious mode of therapy.

Adolescent↗
PubMed2004

Vacuum-ultraviolet beam array generation by flat micro-optical structures.

Micro-optical structures for VUV laser beam shaping and wave-front sensing were manufactured by thin-film deposition onto CaF2 and transfer by etching. Arrays of Bessel-like F2 laser beams at a wavelength of 157 nm with extremely small conical angles were generated by microaxicon lenses. Beam propagation was studied in simulations and experiments. Apodization by absorbing layers is proposed for beam cleaning.

Journal Article↗
PubMed2004

[Diagnosis and treatment of autoimmune thyroiditis].

In Germany, autoimmune thyroiditis usually manifests as atrophic thyroiditis with functional hypothyroidism affecting elderly women in particular. Sonography and thyroid peroxidase antibodies (TPO antibodies) point the way to the diagnosis. Manifest hypothyroidism always requires substitution with levothyroxine. Many patients with subclinical hypothyroidism, especially those with positive thyroid antibodies, benefit from at least partial thyroxine substitution. Early treatment not only alleviates the clinical symptoms, but may possibly also diminish the associated cardiovascular risk. In pregnant and sterile women subclinical hypothyroidism should always be treated.

Adult↗
PubMed2004

[Drug-induced headache and pain reduction medication with amitriptyline in an 11-year old pupil].

We report on an 11-year-old pupil who present-ed to a neurological practice in the company of his parents because of migraine and strong headaches. Precise anamnesis of drugs yielded the diagnosis of a drug-induced headache with underlying migraine disease. The boy was afflict-ed with a hereditary taint, as both parents also suffered from migraine. The mother was also continuously in treatment because of a chronic pain disorder. Therapy with up to 50 mg per day of amitriptyline enabled the boy to stop consuming analgesics without suffering from head-aches. Moreover, under 47.5 mg per day of metoprolol, the migraine symptoms did not re-occur.

Amitriptyline↗
PubMed2004

Effects of a combination of recombinant human growth hormone with metformin on glucose metabolism and body composition in patients with metabolic syndrome.

Abdominal obesity and insulin resistance are central findings in metabolic syndrome. Since treatment with recombinant human growth hormone (rhGH) can reduce body fat mass in patients with organic GH deficiency, rhGH therapy may also have favourable effects on patients with metabolic syndrome. However, due to the highly increased risk for type 2 diabetes in these patients, strategies are needed to reduce the antagonistic effect of rhGH against insulin. We conducted a 18-month randomised, double-blind, placebo-controlled study to assess the effect of rhGH in combination with metformin (Met) in patients with metabolic syndrome. 25 obese men (55 +/- 6 years, BMI 33.4 +/- 2.9 kg/m (2)) with mildly elevated fasting plasma glucose (FPG) levels at screening (6.1-8.0 mmol/l) were included. All patients received metformin (850 mg twice daily) either alone or in combination with rhGH (daily dose 9.5 microg/kg body weight). An oGTT was performed at baseline, after 6 weeks, and after 3, 6, 12, and 18 months of therapy. Glucose disposal rate (GDR) was measured by euglycemic hyperinsulinemic clamp at 0 and 18 months and body composition was measured by DEXA every 6 months. In the Met + GH group, IGF-I increased from 146 +/- 56 microg/l to 373 +/- 111 microg/l (mean +/- SD) after 3 months and remained stable after that. BMI did not change significantly in either group during the study. Total body fat decreased by -4.3 +/- 5.4 kg in the Met + GH group and by -2.7 +/- 2.9 kg in the Met + Placebo group (differences between the two groups: p = n. s.). Waist circumference decreased in both groups (Met + GH: 118 +/- 8 cm at baseline, 112 +/- 10 cm after 18 months; Met + Placebo: 114 +/- 7 cm vs. 109 +/- 8 cm; differences between the two groups: p = 0.096). In the Met + GH group, FPG increased significantly after 6 months (5.9 +/- 0.7 vs. 6.7 +/- 0.4 mmol/l; p = 0.005), but subsequently decreased to baseline levels (18 months: 5.8 +/- 0.2 mmol/l). FPG remained stable in the Met + Placebo group until 12 months had elapsed, and then slightly decreased (baseline: 6.2 +/- 0.3, 18 months: 5.5 +/- 0.6 mmol/l, p = 0.02). No significant changes were seen in either group regarding glucose and insulin AUC during oGTT or HbA (1c) levels. GDR at 18 months increased by 20 +/- 39% in Met + GH-group and decreased by -11 +/- 25% in the Met + Placebo group (differences between the two groups: p = 0.07). In conclusion, treatment of patients with metabolic syndrome and elevated FPG levels did not cause sustained negative effects on glucose metabolism or insulin sensitivity if given in combination with metformin. However, since our data did not show significant differences between the two treatment groups with respect to body composition or lipid metabolism, future studies including larger numbers of patients will have to clarify whether the positive effects of rhGH on cardiovascular risk factors that have been shown in patients with GH deficiency are also present in patients with metabolic syndrome, and are additive to the effects of metformin.

Aged↗
PubMed2004

Calcitonin measurement to detect medullary thyroid carcinoma in nodular goiter: German evidence-based consensus recommendation.

Serum calcitonin (CT) has become a very specific and sensitive marker for human medullary thyroid carcinoma (MTC), a neuroendocrine tumor affecting about 1 % of patients with nodular thyroid disease. MTC is characterized by early micrometastasis and a lack of curative non-surgical treatment, so that early diagnosis is desirable. Based on a systematic review of scientific evidence, we propose multidisciplinary consensus recommendations for the clinical use of CT in patients with nodular goiter. To exclude MTC, serum CT should be determined in patients with nodular thyroid disease, using a two-site CT immunoassay. If basal serum CT exceeds 10 pg/ml, CT should be analysed by pentagastrin stimulation testing, after renal insufficiency and proton pump inhibitor medication have been ruled out. As the risk for MTC is higher than 50 % in patients with stimulated CT values > 100 pg/ml, thyroidectomy is advised in these individuals. If stimulated CT exceeds 200 pg/ml, thyroidectomy and lymphadenectomy is strongly recommended. Pentagastrin-stimulated CT values < 100 pg/ml are associated with a low risk of MTC, or very rarely, non-metastasizing micro-MTC (size < 10 mm). Therefore, regular clinical and biochemical follow-up is the preferred treatment in such patients, unless thyroid malignancy is suspected otherwise.

Calcitonin↗
PubMed2004

Impact of disease activity on thyroid diseases in patients with acromegaly: basal evaluation and follow-up.

In patients with acromegaly, the exact incidence of thyroid disorders is still controversial and less is known about the impact of disease activity and successful treatment. To address this issue, we investigated 73 acromegalic patients (age 55 +/- 13 yr; mean +/- SD) by ultrasonography in comparison to an age-matched control group (54 +/- 1 yr) in the same moderate iodine deficient area (retrospective study). These non-acromegalic volunteers (n = 199) were examined in the same clinic during a thyroid screening test. At the time of examination, 52 (71.2 %) of the acromegalic patients were active, 17 (23.3 %) were cured, and 4 (5.5 %) were controlled with somatostatin analogues. The prevalence of goiter (normal range < 18 ml female, < 25 ml male) was significantly higher (82.2 %) in the mixed group of acromegalics (active, well controlled, cured; n = 73) and in the active group (90.4 %) than in the control group (n = 199, 18.1 %, p < 0.001). Thyroid nodules were found in 63.0 % of the mixed group of acromegalics and in 71.2 % of patients with active disease (33.1 % in controls, p < 0.001). (99 m)Tc scintigraphy revealed thyroid autonomy in 9/73 (12.3 %) and cold nodules in 19/73 (26.0 %) patients. Thyroid cancer was diagnosed in 4 (5.5 %) of acromegalic patients (3 papillary and 1 follicular carcinoma). We found a weak correlation between the disease duration and the initial thyroid volume (r = 0.54, p < 0.0056). Thirty-seven newly diagnosed acromegalics were followed over a period of 7.3 +/- 4.1 years. 5 (13.5 %) of these patients remained active, 8 (21.6 %) were controlled with somatostatin analogues, and 24 (64.9 %) were cured. The mean age, sex distribution, disease duration, prevalence of TSH-deficiency, and initial thyroid volume (46 +/- 11 ml in active, 42 +/- 7 ml in controlled, and 45 +/- 5 ml in cured patients) did not differ statistically between the three groups. In patients with active acromegaly, thyroid volume increased by 19.5 +/- 8.1 %. In contrast, thyroid volume decreased in the group of medically controlled and cured acromegalics (- 21.5 +/- 7.1 %; p < 0.005 and - 24.2 +/- 5.7 %; p < 0.002, respectively). No correlation was found between thyroid volume and TSH levels, levothyroxine and/or iodide administration neither in TSH sufficient nor in TSH insufficient patients. In conclusion, successful treatment of patients with active acromegaly decreases thyroid volume. Cold nodules and thyroid cancer frequently occur in acromegalic patients.

Acromegaly↗
PubMed2004

Subchronic effects of olanzapine on sleep EEG in schizophrenic patients with predominantly negative symptoms.

BACKGROUND: It is well known that sleep disturbance is an integral symptom of schizophrenia. In recent studies, a deficit of delta sleep has been observed in schizophrenic patients. Antipsychotic drugs with serotonin (5-HT2) receptor-antagonistic properties are considered to have delta sleep promoting effects. We have investigated the effects of subchronic olanzapine treatment on sleep EEG in schizophrenic patients. METHODS: The effects of administration of olanzapine (15 to 20 mg) on sleep were studied for four weeks in 10 male, drug-free patients suffering from schizophrenia with predominantly negative symptoms. Conventional sleep EEG parameters were investigated at baseline and after treatment with olanzapine for four weeks. Additionally, spectral power analysis of the EEG signal in distinct frequency bands was computed for different sleep stages. Psychopathology (PANSS, HAMD-17, HAMA) and side effects were assessed weekly. RESULTS: All patients improved, as measured by PANSS global scores. Compared to baseline, there was a significant improvement of parameters of sleep efficiency and an increase of delta sleep as well as REM sleep. Regarding spectral power values, no significant differences between baseline and treatment conditions were found. CONCLUSIONS: Sleep improvement was due to parameters of sleep efficiency and delta sleep, which may be related to serotonin antagonistic properties of olanzapine.

Adolescent↗