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Biomedical subjects

H J Schneider

Publications and source records attributed to H J Schneider.

At least 19 recordsLinked to original sources
PubMed2006

Prevalence of anterior pituitary insufficiency 3 and 12 months after traumatic brain injury.

OBJECTIVE: Cross-sectional studies report a high prevalence of hypopituitarism after traumatic brain injury (TBI); however, no longitudinal studies on time of manifestation and reversibility exist. This study was conducted to assess hypopituitarism 3 and 12 months after TBI. DESIGN: This was a prospective, longitudinal, diagnostic study. METHODS: Seventy-eight patients (52 men, 26 women, mean age 36.0 years) with TBI grades I-III and 38 healthy subjects (25 men, 13 women, mean age 36.4 years) as a control group for the GHRH + arginine test were studied. The prevalence of hypopituitarism was assessed 3 and 12 months after TBI by GHRH + arginine test, short adrenocorticotropic hormone (ACTH) test, and basal hormone measurements in patients. RESULTS: After 3 months, 56% of all patients had impairments of at least one pituitary axis with axes being affected as follows: gonadotropic 32%, corticotropic 19%, somatotropic 9% and thyrotropic 8%. After 12 months, fewer patients were affected, but in some cases new impairments occurred; 36% still had impairments. The axes were affected as follows after 12 months: gonadotropic 21%, somatotropic 10%, corticotropic 9% and thyrotropic 3%. CONCLUSIONS: Hypopituitarism occurs often in the post-acute phase after TBI and may normalize later, but may also develop after the post-acute phase of TBI.

Adult↗
PubMed2006

Discrepant results in the diagnosis of GH deficiency with the insulin-tolerance test and the GHRH plus arginine test in patients with traumatic brain injury.

OBJECTIVE: Patients with traumatic brain injury (TBI) are at moderate risk of GH deficiency (GHD), requiring a diagnostic test with high specificity. The GHRH + arginine (GHRH + ARG) test has been recommended as a reliable alternative to the insulin-tolerance test (ITT) as a standard test with a cutoff level of 9 ng/ml. However, it has recently been questioned for its low specificity in obese subjects, and now BMI-dependent cut-off levels are available. In this study, we compared the ITT and GHRH + ARG test in patients with TBI. DESIGN: A cross-sectional study METHODS: We performed an ITT and a GHRH + ARG test in 21 patients with TBI (6 women, 15 men; mean age 40.2 +/- 12.1 years; BMI 30.7 +/- 6.2). The number of patients classified discordantly as GH deficient by the ITT and the GHRH + ARG test with both classical and BMI-dependent cut-off levels was assessed. RESULTS: Using the GHRH + ARG test with the classical cut-off ( 3 ng/ml), and one patient as GH sufficient who had a blunted GH response to ITT (discordance rate 61.9%). All patients discordantly classified as GH deficient by the GHRH + ARG test had a BMI of >or= 28. With the BMI-dependent cut-offs (4.2, 8.0, and 11.5 ng/ml in obese, overweight, and lean subjects respectively), only 3 of the 21 patients were discordantly classified (discordance rate 14.3%). CONCLUSIONS: Our results discourage the use of a cut-off level of 9 ng/ml for the GHRH + ARG test in obese subjects. The diagnostic reliability of this test is improved with the BMI-dependent cut-offs.

Adult↗
PubMed2006

Endocrine dysfunction in patients operated on for non-pituitary intracranial tumors.

OBJECTIVE: Hypopituitarism frequently follows pituitary neurosurgery (NS) and/or irradiation. However, the frequency of hypothalamic-pituitary dysfunction after NS of non-pituitary intracranial tumors is unclear. The aim of this study was to assess the presence of endocrine alterations in patients operated on for intracranial tumors. DESIGN: This is a retrospective study. METHODS: We studied 68 consecutive adult patients (28 female, 40 male, age 45.0 +/- 1.8 years; body mass index (BMI): 26.5 +/- 0.6) with intracranial tumors who underwent NS only (n = 17) or in combination with radiotherapy (RT) and/or chemotherapy (CT) (n = 51). In all subjects, basal endocrine parameters and the GH response to GHRH + arginine test (using BMI-dependent cut offs) were evaluated. RESULTS: In 20.6% of the patients, peripheral endocrinopathy related to CT and/or RT was present. Hypopituitarism was found in 38.2% of the patients. Total pituitary hormone, multiple pituitary hormone, and isolated pituitary hormone deficits were present in 16.2, 5.8, and 16.2% respectively. The most common pituitary deficits were, in decreasing order: LH/FSH 29.4%, GH 27.9%, ACTH 19.1%, TSH 17.7%, and diabetes insipidus 4.4%. Hyperprolactinemia was present in 13.2%. The prevalence of hypopituitarism was higher in patients who underwent NS only and with tumors located closely to the sella turcica, but a substantial proportion of patients with tumors not directly neighboring the sella also showed hypopituitarism. CONCLUSIONS: Hypopituitarism frequently occurs after NS for intracranial tumors. Also, exposure of these patients to CT and/or RT is frequently associated with peripheral endocrinopathies. Thus, endocrine evaluation and follow-up of patients treated for intracranial tumors should be performed on a regular basis.

Adult↗
PubMed2005

[The genetics of hypogonadotropic hypogonadism in the male].

Underlying causes of hypogonadotropic hypogonadism are acquired or congenital disorders of the hypothalamus or pituitary (e.g. pituitary adenoma, craniopharyngioma, prior radiotherapy, trauma, severe general diseases, extreme stress, genetic mutations). In addition to a comprehensive history and physical examination, the diagnostic work-up includes measurement of testosterone, LH and FSH, with the aim of differentiating between primary and secondary hypogonadism. Where indicated, investigation of pituitary function, the use of imaging procedures, possibly an olfactory test, a GnRH stimulation test or genetic analyses may be added. Depending upon the indication, treatment is effected with testosterone, GnRH or gonadotropines.

Adolescent↗
PubMed2005

Improving fertility in beef cow recipients.

In the 1970s, bovine embryo transfer (ET) shifted from research in a laboratory environment to commercialization of this technology for beef producers. With the quarantine requirements and expense of importing Continental breeds of cattle from Europe, embryo transfer became the logical means to reproduce greater numbers of these animals at a lower cost. The ET industry grew very rapidly and soon would become what it is today, a common practice utilized by select ranchers and breeders. Research over the years has primarily focused on methods to increase the number of ovulations and fertilized ova from the donor female, but the total number of transferable embryos has not changed markedly in the last 20 years. More recent advances have been in the area of in vitro production of embryos that allow for greater numbers of embryos to be produced and easier accessibility to incorporate technologies such as sexed sperm, sperm injection, or transgenics. This paper will focus on the second part of the equation, the recipient, and decisions that will enable both the customers and practitioners to most efficiently utilize embryos from superovulation, in vitro production, or nuclear transfer, so that the maximum number of pregnancies can be produced.

Animals↗
PubMed2005

Endocrine disturbances in depression.

Depression is one of the most common psychiatric disorders. For a long time, clinicians suspected a causal link between depression and the endocrine system. The most frequently occurring endocrine abnormality in depressed subjects is hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. CRH and AVP are likely to play a substantial role in the pathophysiology of this disorder, and their receptors appear to be a specific target for future antidepressant drugs. Depression also affects the hypothalamic-pituitary-GH (HPGH) and -thyroid (HPT) axes. Alterations in the reproductive system may also play a role in the pathology of depression. In addition, there is increasing evidence that leptin and neurosteroids, such as DHEA, are implicated in mood disorders.

Depressive Disorder↗
PubMed2004

[Pituitary insufficiency following head injury--how common is it, and what is to be done?].

In Germany,traumatic brain injury (TBI) has an annual incidence of approximately 200000. In contrast to earlier assumptions, pituitary insufficiency is a common complication of TBI, with a prevalence of 30-50%. Since the symptoms are often nonspecific and may be masked by the sequelae of head injury, it may go unrecognized and may possibly aggravate the symptomatology of such injury. It is therefore to be recommended that patients who suffer a head injury should be examined to exclude pituitary gland insufficiency, by measuring the basal hormone level--where necessary in combination with stimulation tests.

Brain Injuries↗
PubMed2004

The effect of growth hormone substitution on cognitive performance in adult patients with hypopituitarism.

OBJECTIVE: Adult hypopituitary patients with growth hormone deficiency, though on adequate adrenal, thyroid or sex hormone replacement therapy, complain of attention and memory disabilities. During the past years several studies have evidenced that growth hormone (GH) may exert distinctive effects on the central nervous system and induce beneficial effects on psychological capabilities. The aim of our study was to determine whether a long-term replacement therapy of recombinant human growth hormone (rhGH) affects cognitive performance in adults with GH deficiency. DESIGN: A double-blind, randomized placebo controlled trial over 6 months, followed by an open period of 6 months of rhGH treatment. MEASUREMENTS: The assessment of cognitive performance comprised attention, verbal memory and non-verbal intelligence and was examined at baseline (0), at 3, 6, 9, and 12 months. In addition, emotional well-being and energy were assessed using the Nottingham Health Profile self rating questionnaire. PATIENTS: Eighteen hypopituitary patients, mean age 41.6 (range 21-63) years with adult onset GH deficiency were evaluated. Patients were on adequate and stable adrenal, thyroid, gonadal and desmopressin replacement therapy where necessary, but not substituted for GH deficiency. RESULTS: After 3 and 6 months of rhGH treatment in the closed label phase a significant improvement of attentional performance was observed compared to baseline in the rhGH group but not in the placebo group. After 6 months scores of attention were significantly different between rhGH and placebo treatment for the digit cancellation test and marginally different for the trail-making test. In contrast, long-term verbal memory and non-verbal intelligence did not improve compared to baseline during therapy and short-term memory improved both in the GH and the placebo group after 3 and 6 months. This was considered as a placebo or practice effect. In the open-label phase a further improvement of attention was found in the GH group and subsequent treatment with rhGH for 3 and 6 months in the placebo group also significantly improved attentional performance supporting the results of the rhGH group in the first 6 months of the double-blind phase. CONCLUSION: RhGH treatment appears to have a beneficial effect on attentional performance in adult hypopituitary patients with GH deficiency when treated for at least 3 months. Our study does not support a role for GH in influencing verbal memory or non-verbal intelligence.

Adult↗
PubMed2001

A first comparison of solid state and solution structure of a complex between lanthanum nitrate and 1,9-diaza-18-crown-6.

[figure: see text] The structure of the complex between lanthanum(III)nitrate and 1,9-diaza-18-crown-6 is analyzed with three independent methods. The conformation observed by analysis of vicinal NMR coupling constants in solution agrees with both the one found by a single crystal X-ray study and with simulations by molecular orbital and force field calculations. In the acetonitrile solution, the NMR data show a bent crown conformation with nearly C2v symmetry, which is stable on the NMR time scale.

Journal Article↗
PubMed2000

Affinity and nuclease activity of macrocyclic polyamines and their CuII complexes.

The stability constants of Cu(II) complexes that consist of either an oxaaza macrocycle with two triamine moieties linked by dioxa chains, or two macrocyclic ligands with a polyamine chain which are connecting the 2 and 9 positions of phenanthroline, have been determined by means of potentiometric measurements. The results are compared to those reported for other ligands with a similar molecular architecture. Of the complexes that contain phenanthroline in their macrocycle, the Cu(II) ion of the complex with the smallest and most rigid macrocycle (L3) has an unsaturated coordination sphere, while in the complex with the largest macrocycle (L5) the Cu(II) ion is coordinatively almost saturated. These results are corroborated by the crystal structure of the [CuL5](ClO4)2 complex. The affinity of the ligands and the complexes towards nucleic acids was studied by measuring the changes in the melting temperature, which showed that the affinity of the macrocyclic ligands towards double-stranded DNA or RNA is generally smaller than that of their linear analogues that bear a similar charge, with a strong preference for polyA-polyU, a model for RNA. However, the complexes of two of the changed macrocyclic ligands which contain a phenanthroline unit (L4, L5) showed a distinctly larger increase in their melting temperature deltaTm with DNA (polydA-polydT), which is reversed again in favor of RNA upon metallation to the dinuclear copper complex with L5. Experiments with supercoiled plasmid DNA showed a particularly effective cleavage with a mononuclear Cu(II) complex that contains a phenanthroline unit (L6). Related ligands showed less activity towards DNA, but not so towards the biocidic bis(p-nitrophenyl)phosphate (BNPP). In both cases (with DNA and BNPP) the activity seemed to increase with decrease of coordinative saturation of the Cu(II) ion, with the exception of one particular ligand (L6). Experiments with radical scavengers in the DNA experiments showed some decrease in cleavage, which indicates the participation of redox processes.

Binding Sites↗
PubMed1997

[Dysarthric movement disorders of the velopharynx].

In this study we developed another method for the detection of nasopharyngeal closing patterns. This investigation of dynamic closure patterns was based on flexible video-nasopharyngoscopy and was undertaken in both healthy subjects and patients with dysarthria. Quantitative assessments of pharyngeal wall excursions allowed evaluation of closure patterns which were then matched with a predefined, mathematically-based algorithm. The results showed that a greater velopharyngeal constriction was maintained in the following order: resonants, open vowels, forced expiration, closed vowels, consonants, and swallowing. Variations in phonetic expressions of phonemes mainly interfered with velum excursion, whereas the lateral pharyngeal mucosal wall was minimally involved and the posterior wall portions were unaffected. Velopharyngeal closure patterns varied with different tasks: the velum was mainly moved for phonetic parameters, while lateral and posterior pharyngeal wall motion was observed on a large scale for swallowing. Comparison of subject groups revealed that patients with dysarthrias had reduced velar motility, leading to a more frequent hypernasal sound. Here, lateral pharyngeal walls showed a variable motility that in some cases was even more than in healthy subjects. Both groups exhibited qualitatively comparable velopharyngeal closure patterns, but significant differences were proved in their distributions.

Adult↗