Hypoxia inducible factor promotes murine allergic airway inflammation and is increased in asthma and rhinitis

BACKGROUND

New therapies are necessary to address inadequate asthma control in many patients. This study sets out to investigate whether hypoxia-inducible factor (HIF) is essential for development of allergic airway inflammation (AAI) and therefore a potential novel target for asthma treatment.

METHODS

Mice conditionally knocked out for HIF-1β were examined for their ability to mount an allergic inflammatory response in the lung after intratracheal exposure to ovalbumin. The effects of treating wild-type mice with either ethyl-3,4-dihydroxybenzoate (EDHB) or 2-methoxyestradiol (2ME), which upregulate and downregulate HIF, respectively, were determined. HIF-1α levels were also measured in endobronchial biopsies and bronchial fluid of patients with asthma and nasal fluid of patients with rhinitis after challenge.

RESULTS

Deletion of HIF-1β resulted in diminished AAI and diminished production of ovalbumin-specific IgE and IgG(1) . EDHB enhanced the inflammatory response, which was muted upon simultaneous inhibition of vascular endothelial growth factor (VEGF). EDHB and 2ME antagonized each other with regard to their effects on airway inflammation and mucus production. The levels of HIF-1α and VEGF increased in lung tissue and bronchial fluid of patients with asthma and in the nasal fluid of patients with rhinitis after challenge.

CONCLUSIONS

Our results support the notion that HIF is directly involved in the development of AAI. Most importantly, we demonstrate for the first time that HIF-1α is increased after challenge in patients with asthma and rhinitis. Therefore, we propose that HIF may be a potential therapeutic target for asthma and possibly for other inflammatory diseases.

Symbolic coupling traces for causality analysis of cardiovascular control

Directional coupling analysis of time series is an important subject of current research. In this paper, a method based on symbolic dynamics for the detection of time-delayed coupling in biosignals is presented. The symbolic coupling traces, defined as the symmetric and diametric traces of the bivariate word distribution, allow for a more reliable quantification of coupling and are compared with established methods like mutual information and cross recurrence analysis. The symbolic coupling traces method is applied to appropriate model systems and cardiological data which demonstrate its advantages especially for nonstationary and noisy data. Moreover, the method of symbolic coupling traces is used to analyze and quantify time-delayed coupling of cardiovascular measurements during different sleep stages. Significant different regulatory mechanisms are detected not only between the deep sleep and the other sleep stages but also between healthy subjects and patients. The proposed method may help to indicate pathological changes in cardiovascular regulation and also effects of continuous positive airway pressure therapy on the cardiovascular system.

Cardiovascular regulation during sleep quantified by symbolic coupling traces

Sleep is a complex regulated process with short periods of wakefulness and different sleep stages. These sleep stages modulate autonomous functions such as blood pressure and heart rate. The method of symbolic coupling traces (SCT) is used to analyze and quantify time-delayed coupling of these measurements during different sleep stages. The symbolic coupling traces, defined as the symmetric and diametric traces of the bivariate word distribution matrix, allow the quantification of time-delayed coupling. In this paper, the method is applied to heart rate and systolic blood pressure time series during different sleep stages for healthy controls as well as for normotensive and hypertensive patients with sleep apneas. Using the SCT, significant different cardiovascular mechanisms not only between the deep sleep and the other sleep stages but also between healthy subjects and patients can be revealed. The SCT method is applied to model systems, compared with established methods, such as cross correlation, mutual information, and cross recurrence analysis and demonstrates its advantages especially for nonstationary physiological data. As a result, SCT proves to be more specific in detecting delays of directional interactions than standard coupling analysis methods and yields additional information which cannot be measured by standard parameters of heart rate and blood pressure variability. The proposed method may help to indicate the pathological changes in cardiovascular regulation and also the effects of continuous positive airway pressure therapy on the cardiovascular system.

Alcohol acutely increases vascular reactivity together with insulin sensitivity in type 2 diabetic men

Moderate alcohol consumption is associated with increased insulin sensitivity and reduced cardiovascular risk. We hypothesized that this relates to a direct effect of alcohol and therefore investigated whether acute alcohol intake altered insulin sensitivity or endothelial function in patients with type 2 diabetes. In an open-label two period design, the effect of a single oral dose of 40 g of alcohol (168 ml 40% vodka) on an insulin-modified frequently sampled intravenous glucose tolerance test (FSIGT) and on endothelium-dependent (flow mediated, FMD) or endothelium-independent (glyceroltrinitrate (GTN)-induced) vasodilation of the brachial artery measured by ultrasound was studied. Experiments were carried out in twelve male patients with type 2 diabetes mellitus (64+/-6 years, body mass index 28.4+/-5.7 kg/m (2)). Baseline insulin sensitivity index (S (I)) was 1.10+/-0.34 min (-1).microU (-1).ml, baseline FMD was +4.1+/-3.0%, and GTN-induced vasodilation +7.4+/-2.3% from resting brachial artery diameter. Acute alcohol intake increased alcohol plasma levels to 0.33+/-0.04 per thousand, S (I) to 1.86+/-0.45 min (-1).microU (-1).ml (p<0.05), and FMD to +8.2+/-2.8% (p<0.05), while GTN-induced dilation remained unchanged. No relationship was detectable between the observed changes. We conclude that alcohol intake acutely increases endothelium-dependent brachial artery vasodilation in patients with type 2 diabetes together with insulin sensitivity. This acute effect might explain some beneficial effects of low alcohol consumption in epidemiological observations.

HbA1c values calculated from blood glucose levels using truncated Fourier series and implementation in standard SQL database language

OBJECTIVES

This article presents a mathematical model to calculate HbA1c values based on self-measured blood glucose and past HbA1c levels, thereby enabling patients to monitor diabetes therapy between scheduled checkups. This method could help physicians to make treatment decisions if implemented in a system where glucose data are transferred to a remote server. The method, however, cannot replace HbA1c measurements; past HbA1c values are needed to gauge the method.

METHODS

The mathematical model of HbA1c formation was developed based on biochemical principles. Unlike an existing HbA1c formula, the new model respects the decreasing contribution of older glucose levels to current HbA1c values. About 12 standard SQL statements embedded in a php program were used to perform Fourier transform. Regression analysis was used to gauge results with previous HbA1c values. The method can be readily implemented in any SQL database.

RESULTS

The predicted HbA1c values thus obtained were in accordance with measured values. They also matched the results of the HbA1c formula in the elevated range. By contrast, the formula was too "optimistic" in the range of better glycemic control. Individual analysis of two subjects improved the accuracy of values and reflected the bias introduced by different glucometers and individual measurement habits.

Interactions of glucose metabolism and chronic heart failure

BACKGROUND

We evaluated insulin sensitivity and beta cell function in patients with chronic heart failure (CHF), and investigated a possible correlation of these metabolic parameters with specific biomarkers of heart failure. Additionally, we investigated the effects of two angiotensin receptor blockers (ARBs), namely telmisartan and candesartan, that were administered over a 5 month treatment period, as additional therapy to standard care.

METHODS AND RESULTS

The study group consisted of 94 CHF patients. Insulin sensitivity (OGIS index) and insulin secretion parameters were investigated by frequently sampled oral glucose tolerance tests and consecutive mathematical modelling. In total, 94.6 % of patients had clinically overt diabetes, impaired glucose tolerance or insulin resistance at the time of enrolment HbA1c was found to correlate to NT-proBNP, MR-proADM, CT-proET-1, and MR-proANP, but not to Copeptin. NT-proBNP correlated inversely to OGIS. None of the metabolic parameters were altered significantly after candesartan or telmisartan treatment in either the patient or standard care group.

CONCLUSION

Insulin sensitivity and insulin secretion are impaired in CHF and biomarkers of heart failure and atherosclerotic disease correlate to glucose metabolism.

Modeling the cardiovascular system using a nonlinear additive autoregressive model with exogenous input

The parameters of heart rate variability and blood pressure variability have proved to be useful analytical tools in cardiovascular physics and medicine. Model-based analysis of these variabilities additionally leads to new prognostic information about mechanisms behind regulations in the cardiovascular system. In this paper, we analyze the complex interaction between heart rate, systolic blood pressure, and respiration by nonparametric fitted nonlinear additive autoregressive models with external inputs. Therefore, we consider measurements of healthy persons and patients suffering from obstructive sleep apnea syndrome (OSAS), with and without hypertension. It is shown that the proposed nonlinear models are capable of describing short-term fluctuations in heart rate as well as systolic blood pressure significantly better than similar linear ones, which confirms the assumption of nonlinear controlled heart rate and blood pressure. Furthermore, the comparison of the nonlinear and linear approaches reveals that the heart rate and blood pressure variability in healthy subjects is caused by a higher level of noise as well as nonlinearity than in patients suffering from OSAS. The residue analysis points at a further source of heart rate and blood pressure variability in healthy subjects, in addition to heart rate, systolic blood pressure, and respiration. Comparison of the nonlinear models within and among the different groups of subjects suggests the ability to discriminate the cohorts that could lead to a stratification of hypertension risk in OSAS patients.

Insulin resistance has no impact on ghrelin suppression in pregnancy

Ghrelin is reduced in various states of insulin resistance. The aim of this study was to examine the relationship between ghrelin and glucose metabolism during pregnancy - a natural insulin-resistant state - in women with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) or gestational diabetes mellitus (GDM) and potential changes 3 months after delivery. A total of 54 women, 37 pregnant and with various degrees of insulin resistance and 24 postpartum (PP, seven of them also studied during pregnancy) were studied. Ghrelin plasma concentrations at fasting and 60' following glucose loading (75 g-2 h-oral glucose tolerance test), area under the curve of plasma glucose (G-AUC(OGTT)) and insulin sensitivity [homeostatic model assessment (HOMA) and oral glucose sensitivity index (OGIS) indices, respectively] were determined. Both baseline and 60' ghrelin concentrations were to a comparable degree ( approximately by 65%) suppressed in NGT, IGT and GDM as compared to the PP group (the latter being indistinguishable from NGT regarding glucose tolerance and insulin sensitivity). In all women studied both during and after pregnancy, ghrelin levels rose from pregnancy to PP (mean increase 313.8%; P < 0.03). There was no correlation between baseline ghrelin and insulin sensitivity as estimated from both baseline (HOMA) and dynamic (OGTT:OGIS) glucose and insulin data. Ghrelin is substantially decreased during pregnancy, but glucose-induced ghrelin suppression is preserved at a lower level. There is apparently no relation to the degree of insulin resistance.

Bilateral, simultaneous rupture of the quadriceps tendon: a diagnostic pitfall? Report of three cases and meta-analysis of the literature

Bilateral, simultaneous quadriceps tendon rupture (QTR) represents a rare entity and delay in establishing the correct diagnosis is not uncommon. Another three cases are reported here and in all the correct diagnosis was missed initially. A review of the English and German literature retrieved 105 cases of bilateral, simultaneous QTR and in 32 patients (30.5%) the correct diagnosis was established with delay. In 28 cases--representing 25 men (89.3%) and 3 women (10.7%)--sufficient data was available for further analysis. In the majority of patients (n = 19/28; 67.9%) rupture was associated with trauma, while no trauma was reported in 9/28 cases (32.1%). No direct correlation between age and the kind of rupture form (traumatic/spontaneous) could be detected (P = 0.35). Most partients (n = 18/28; 64.3%) presented risk factors associated with QTR and obesity (n = 6/28; 21.4%) was most frequently encountered. A direct association between the rate of risk factors and the rupture form was not seen (P = 0.5). Overall diagnostic delay lasted 64.7 days on an average (traumatic ruptures 67.7 days/spontaneous ruptures 58.7 days) with this period being longer than 2 weeks in 51.9% and longer than 3 months in 33.3% of patients. Delay varied distinctly in different medical institutions as this period lasted in hospital departments 93.9 days, in ambulances 24 days and in General Practitioners 7.6 days on an average. Initially 25 incorrect diagnoses were established in 21/28 (75%) patients, while 7/28 cases (25%) were discharged initially without any diagnosis. Clinical examination revealed most often palpable suprapatellar gaps (n = 17/24) and effusions (n = 13/24), while the classic trias of painful swelling, suprapatellar gap and loss of knee extension was found in only 58.3% of reported patients (n = 14/24). The correct diagnosis of bilateral QTR was established in 60.7% (n = 17/28) by history and clinical examination alone. In 10.7% (n = 3/28) clinical suspect was supported by sonography and in 14.3% (n = 4/28) by MRT; in 14.3% (n = 4/28) the correct diagnosis represented a by chance finding during diagnostic or operative procedures of other indication. In 52 tendons detailed information about repair was provided and most often transosseous fixation (n = 30/52; 57.7%) and direct repair (n = 14/52; 26.9%) were used, while a tenoplasty was performed in only 15.4% (n = 8/52). Only 34.6% of patients (n = 9/26) with follow-up data (n = 26/28) reported a full recovery with a trend that early surgical repair (limit 2 weeks) improves the final outcome.

Tuberkulöse Osteomyelitis des Klivus mit Beteiligung des Nasopharynx

Involvement of the skull base is rare in tuberculosis. We report here the case of a 28-year-old female patient with an osteolytic process of the clivus with compression of the brain stem and involvement of the nasopharynx. She reported suffering from headaches for the last 6 months, and diplopia had occurred 1 week before her diagnosis as a result of paresis of the VIth cranial nerve on the right side. A biopsy was obtained endoscopically via a transnasal approach, revealing a granulomatous inflammation with acid-fast rods and thus confirming the diagnosis of a tuberculoma. When the biopsy was taken there was no evidence of any further tuberculomas in this patient. The clinical picture, diagnosis, and treatment of tuberculosis of the skull base and nasopharynx are discussed and the literature on this rare clinical entity is reviewed with reference to this patient's case report.

Pituitary function in patients with newly diagnosed untreated systemic lupus erythematosus

OBJECTIVES

To determine whether hormonal dysfunction involving the hypothalamic-pituitary-adrenal (HPA) axis, prolactin (PRL) secretion, and sex hormone status contribute to development of systemic lupus erythematosus (SLE).

METHODS

11 patients with SLE and 9 healthy controls were tested for their total anterior pituitary gland reserve by simultaneous injection of corticotropin-, growth hormone- (GH), thyrotropin-, and gonadotropin-releasing hormone (GnRH). Serum concentrations of adrenocorticotropin (ACTH), cortisol, GH, thyroid stimulating hormone (TSH), PRL, luteinising hormone (LH), and follicle stimulating hormone (FSH) were measured at baseline and after injection. Baseline values of oestradiol, testosterone, and thyroxine were determined.

RESULTS

Basal and stimulated serum concentrations of ACTH, cortisol, GH, and PRL were similar in both groups. In contrast, despite similar basal thyroxine levels the TSH response to TRH was significantly higher in patients than in controls. LH and FSH levels in premenopausal female patients of both groups were identical. In contrast, two of the three male patients were hypogonadal without compensatory increases of basal LH and FSH levels, but they retained excessive stimulatory capacity in response to GnRH.

CONCLUSION

No significant alteration of the HPA axis was found in patients with SLE, which is inadequate in view of the continuing inflammation. GH and PRL secretion were normal. The pituitary-thyroid and pituitary-gonadal axes were affected in patients with newly diagnosed, untreated SLE.

Pro- and anti-inflammatory cytokine production by autoimmune T cells against preproinsulin in HLA-DRB1*04, DQ8 Type 1 diabetes

AIMS/HYPOTHESIS

Preproinsulin is a target T cell autoantigen in human Type 1 diabetes. This study analyses the phenotype and epitope recognition of preproinsulin reactive T cells in subjects with a high genetic risk of diabetes [HLA-DRB1*04, DQ8 with Ab+ (autoantibody-positive) or without islet autoantibodies (control subjects)], and in HLA-matched diabetic patients.

METHODS

A preproinsulin peptide library approach was used to screen for cytokine profiles and epitope specificities in human peripheral blood lymphocytes, and CD4(+)CD45RA(-) and CD4(+)CD45RA(+) T cell subfractions, representing memory and naive and recently primed T cells respectively.

RESULTS

In CD4(+) T cell subsets we identified immunodominant epitopes and cytokine production patterns that differed profoundly between patients, Ab+ subjects and non-diabetic HLA-matched control subjects. In Ab+ subjects, a C-peptide epitope C13-29 and insulin B-chain epitope B11-27 were preferentially recognised, whereas insulin-treated Type 1 diabetic patients reacted to native insulin and B-chain epitope B1-16. In peripheral blood lymphocytes of Ab+ subjects, an increase in T helper (Th) 1 (IFNgamma, IL-2) and Th2 (IL-4) cytokines was detectable, wheras in CD45RA(+) and CD45RA(-) subsets, IL-4 and IL-10 phenotypes dominated, compatible with the contribution of non-CD4 cells to IFNgamma content. In insulin-treated Type 1 diabetic patients, naive and recently primed CD4(+) cells were characterised by increasd IFNgamma, TNFalpha, and IL-5.

CONCLUSIONS/INTERPRETATION

Our data show that T cell reactivity to preproinsulin in CD45RA subsets is Th2-dominant in Ab+ subjects, challenging the Th1 paradigm in Type 1 diabetes. Characteristic immunodominant epitopes and cytokine patterns distinguish diabetic patients and Ab+ subjects from HLA-matched healthy individuals. This could prove useful in monitoring of T-cell immunity in clinical diabetes intervention trials.

[Growth hormone in the elderly man]

Many symptoms being part of the growth hormone deficiency syndrome in adults like decrease in muscle mass and bone mineral content, increase in fat mass, and skin atrophy are observed also with ageing. Indeed, short term trials with growth hormone administration to persons over 60 years old revealed that many of these symptoms could be reversed by growth hormone. However, recent reports of an association of high insulin-like growth factor-1 (IGF-1)-concentrations and increased risk of prostate, lung, colon and breast cancer as well as a possible decrease of insulin sensitivity prohibit currently the use of growth hormone in an attempt to reverse a normal ageing process. Prospective, randomised and placebo-controlled long-term trials are necessary to prove safety and efficacy of growth hormone therapy in the ageing population before it can be recommended. In addition, no data are available as to the right growth hormone dose and the correct monitoring. Expectations of the society and the search for the fountain of youth should not motivate physicians to leave the firm ground of evidence based medicine and prescribe experimental therapies to healthy older persons.

Differential effects of growth hormone therapy in malnourished hemodialysis patients

BACKGROUND

Malnutrition is common in chronic hemodialysis patients and is associated with increased morbidity and mortality. Several factors such as metabolic acidosis, hyperparathyroidism, and insulin as well as growth hormone (GH) resistance may lead to enhanced protein catabolism. Recombinant human growth hormone (rhGH) has been proposed as treatment of malnutrition because of its anabolic effects.

METHODS

In the present placebo-controlled, double blind study, the effects of three months of rhGH therapy on nutritional and anthropometric parameters, on bone metabolism and bone mineral density (BMD), as well as on polymorphonuclear leukocyte (PMNL) function and quality of life (QoL) were evaluated in 19 malnourished hemodialysis patients (10 females and 9 males) with a mean age of 59.3 +/- 13.4 years. RhGH (0.125 IU/kg) was given three times a week during the first four weeks and 0.25 IU/kg thereafter three times a week after each dialysis session.

RESULTS

Insulin-like growth factor I (IGF-I) concentration rose significantly from 169.2 +/- 95.6 ng/mL to 262.9 +/- 144.4 ng/mL (p< 0.01) in the group receiving rhGH. Albumin, prealbumin, transferrin, cholesterol, high-density lipoprotein (HDL) cholesterol, cholinesterase, predialytic creatinine, and blood urea nitrogen showed no significant changes during the three months in both groups. Total body fat (%TBF) was slightly reduced after three months (P = NS) in the patients receiving GH, whereas lean body mass (LBM) remained stable during therapy. Procollagen I carboxy terminal peptide (PICP), a marker of bone formation, increased significantly after three months from 250.1 +/- 112.6 to 478.5 +/- 235.2 microg/L (P < 0.01) in the GH-treated patients, whereas parameters of bone resorption like telopeptide ICTP showed only a slight increase (50.3 +/- 18.5 vs. 70.0 +/- 39.5 microg/L, P = NS). BMD at the lumbar spine decreased significantly after three months in the treatment group (0.8 +/- 0.17 vs. 0.77 +/- 0.16 g/cm2, P < 0.01), whereas BMD at the femoral neck remained stable in both groups. Phagocytic activity of PMNLs increased significantly after three months of therapy with rhGH, whereas other parameters of PMNL function were not affected by GH. QoL was slightly improved in the GH treated group, but decreased markedly in the placebo group.

CONCLUSIONS

Three months of treatment with rhGH in malnourished patients on chronic hemodialysis causes a significant increase in IGF-I levels without significant changes in nutritional and anthropometric parameters. In contrast, bone turnover was enhanced with an initial decrease in BMD at the lumbar spine, and phagocytic activity of PMNLs was increased.

Apoplexy of a pituitary macroadenoma with reversible third, fourth and sixth cranial nerve palsies following administration of hypothalamic releasing hormones: MR features

Pituitary apoplexy in patients with pituitary macroadenomas can occur either spontaneously or following various interventions. We present a case of a 71-year-old woman who developed third, fourth, and sixth cranial nerve palsies following administration of the four hypothalamic releasing hormones for routine preoperative testing of pituitary function. The MR examination showed interval tumor growth with impression of the floor of the third ventricle. There were also changes in signal intensity characteristics of the mass, suggestive of intratumoral bleeding. A transsphenoidal surgery with subtotal resection of the pituitary adenoma was performed. Microscopical examination revealed large areas of necrosis and blood surrounded by adenomatous tissue. Third, fourth, and sixth cranial nerve palsies completely resolved within 4 months. We conclude that MR imaging is useful in the demonstration of pituitary apoplexy following preoperative stimulation tests, but we suggest that these tests should be abandoned in patients with pituitary macroadenomas.

The polyglutamine expansion in spinocerebellar ataxia type 6 causes a beta subunit-specific enhanced activation of P/Q-type calcium channels in Xenopus oocytes

Spinocerebellar ataxia type 6 (SCA6) is a dominantly inherited degenerative disorder of the cerebellum characterized by nearly selective and progressive death of Purkinje cells. The underlying mutation in SCA6 consists of an expansion of a trinucleotide CAG repeat in the 3' region of the gene, CACNA1A, encoding the alpha(1A) subunit of the neuronal P/Q-type voltage-gated calcium channel. Although it is known that this mutation results in an expanded tract of glutamine residues in some alpha(1A) splice forms, the distribution of these splice forms and the role of this mutation in the highly selective Purkinje cell degeneration seen in SCA6 have yet to be elucidated. Using specific antisera we demonstrate that the pathological expansion in SCA6 can potentially be expressed in multiple isoforms of the alpha(1A) subunit, and that these isoforms are abundantly expressed in the cerebellum, particularly in the Purkinje cell bodies and dendrites. Using alpha(1A) subunit chimeras expressing SCA6 mutations, we show that the SCA6 polyglutamine expansion shifts the voltage dependence of channel activation and rate of inactivation only when expressed with beta(4) subunits and impairs normal G-protein regulation of P/Q channels. These findings suggest the possibility that SCA6 is a channelopathy, and that the underlying mutation in SCA6 causes Purkinje cell degeneration through excessive entry of calcium ions.

The increased insulin sensitivity in growth hormone-deficient adults is reduced by growth hormone replacement therapy

BACKGROUND

Growth hormone deficiency is associated with increased morbidity and mortality from cardiovascular diseases, which might be related to changes in glucose and lipid metabolism.

DESIGN

To assess the influence of long-term growth hormone replacement therapy (GHRT) on glucose metabolism we examined eight growth hormone-deficient (GHD) adults (seven female/one male; age, 46 +/- 3 years; body mass index, 31 +/- 2 kg m-2) over a period of 18 months in comparison to an adequate control group consisting of eight obese subjects matched for age, sex, and body mass index. We performed frequently sampled intravenous glucose tolerance tests (FSIGT) with minimal model analysis before the study, and after 12 and 18 months.

RESULTS

Following GHRT, insulin-like growth factor-1 (IGF-1) increased significantly from a basal level of 75.9 +/- 18.9 to 200.8 +/- 31.0 microg L-1 after 12 months of therapy and remained stable, thereafter. GHRT did not affect fasting blood glucose, basal insulin, cholesterol, blood pressure and body weight. However, at 12 months, HbA1c (6.0 +/- 0.1 vs. 5.6 +/- 0.1% at basal, P < 0.05) and triglyceride (2.3 +/- 0.4 vs. 1.4 +/- 0.3 mmol L-1) significantly increased but returned to pretreatment values at 18 months. Insulin sensitivity was higher in GHD (8.2 +/- 3.1) compared to controls (3. 6 +/- 0.53 x 10-4 min-1/(microU mL-1), P = 0.06) and decreased significantly after 18 months of GHRT to 5.1 +/- 2.6, P < 0.05. Basal insulin secretion was similar to that in the control group and increased significantly after 12 and 18 months, total insulin secretion only after 12 months. SG (glucose effectiveness)was lower in GHD patients (0.0095 +/- 0.001 min-1) compared to controls (0.020 +/- 0.003 min-1, P < 0.05) and increased significantly after 12 and 18 months of GHRT (0.016 +/- 0.002, and 0.015 +/- 0.001 min-1, P < 0. 05), respectively. Hepatic insulin extraction rate was similar in both groups and remained unchanged following GHRT.

CONCLUSION

We conclude that long-term GHRT induces a significant decrease of the increased insulin sensitivity in GHD patients to levels observed in body mass index-matched control subjects. This is accompanied by an increase in basal and total insulin secretion as well as in glucose effectiveness as a possible compensatory mechanism.

The kappa opioid receptor and dynorphin co-localize in vasopressin magnocellular neurosecretory neurons in guinea-pig hypothalamus

The relationship between the cloned kappa opioid receptor, dynorphin, and the neurohypophysial hormones vasopressin and oxytocin was analysed in the guinea-pig hypothalamic magnocellular neurosecretory neurons. This analysis was performed in order to understand better which population of neuroendocrine neurons in the guinea-pig is modulated by kappa opioid receptors and its endogenous ligand dynorphin. Extensive co-localization was observed between kappa opioid receptor immunoreactivity and preprodynorphin immunoreactivity in neuronal cell bodies in the paraventricular and supraoptic nuclei. Cells positive for either the kappa opioid receptor or both the kappa opioid receptor and preprodynorphin were restricted to the vasopressin expressing neuronal population and not found in the oxytocin expressing neuronal population. The kappa opioid receptor and dynorphin were examined in the posterior pituitary and both were found to be extensively distributed. Staining for the kappa opioid receptor and dynorphin B co-localized in posterior pituitary. In addition, immunogold electron microscopy confirmed that kappa opioid receptor and dynorphin B immunoreactivity were found in the same nerve terminals. Ultrastructural analysis also revealed that kappa opioid receptor immunoreactivity was associated with both nerve terminals and pituicytes. Within nerve terminals, kappa opioid receptor immunoreactivity was often associated with large secretory vesicles and rarely associated with the plasma membrane. Our data suggest that the cloned kappa opioid receptor may directly modulate the release of vasopressin but not oxytocin in guinea-pig hypothalamic magnocellular neurosecretory neurons and posterior pituitary. Furthermore, we propose that this receptor is an autoreceptor in this system because our results demonstrate a high degree of co-localization between kappa opioid receptor and dynorphin peptide immunoreactivity in magnocellular nerve terminals.

Growth hormone replacement therapy is not associated with retinal changes

GH and/or growth factors are thought to play a role in the pathogenesis of diabetic retinopathy. In addition, the occurence of retinal changes mimicking diabetic retinopathy in two GH-deficient (GHD) patients receiving GH replacement therapy (GHRT) has recently been reported. The present study was performed to evaluate whether this was a coincidence or whether GHRT might regularly induce retinal changes. Sixty-one GHD patients on GHRT with a mean age of 42.5 +/-17.3 yr were examined by one ophthalmologist (AR). The mean duration of GHRT was 8.4 +/- 3.7 yr in childhood onset and 3.5 +/- 2.1yr in adult onset patients. Plasma insulin-like growth factor I concentrations were 76.4 +/- 49.6 ng/mL before GHRT and 244.3 +/- 119.2 ng/mL while receiving GHRT with a dose of 1.7 +/- 0.7 IU/day. After pupil dilatation with tropicamide, fundus examinations of both eyes were performed using a Volk 90 diopter fundus lens with a slit lamp (Haag Streit, Bern, Switzerland). In none of the patients were vascular or retinal changes like macular edema, microaneurysms, hemorrhages, hard exsudates, cotton wool spots, preproliferative signs, or proliferations found. The optic discs were also normal in all patients. We conclude, therefore, that long-term GHRT can be administered safely in GHD patients without an increased risk of retinal changes.

Stimulus-dependent translocation of kappa opioid receptors to the plasma membrane

We examined the cellular and subcellular distribution of the cloned kappa opioid receptor (KOR1) and its trafficking to the presynaptic plasma membrane in vasopressin magnocellular neurosecretory neurons. We used immunohistochemistry to show that KOR1 immunoreactivity (IR) colocalized with vasopressin-containing cell bodies, axons, and axon terminals within the posterior pituitary. Ultrastructural analysis revealed that a major fraction of KOR1-IR was associated with the membrane of peptide-containing large secretory vesicles. KOR1-IR was rarely associated with the plasma membrane in unstimulated nerve terminals within the posterior pituitary. A physiological stimulus (salt-loading) that elicits vasopressin release also caused KOR1-IR to translocate from these vesicles to the plasma membrane. After stimulation, there was a significant decrease in KOR1-IR associated with peptide-containing vesicles and a significant increase in KOR1-IR associated with the plasma membrane. This stimulus-dependent translocation of receptors to the presynaptic plasma membrane provides a novel mechanism for regulation of transmitter release.

Adrenal function in patients with chronic renal failure

Previous studies have reported divergent findings on the function of the hypothalamic-pituitary-adrenal axis in patients with chronic renal failure (CRF). The low-dose adrenocorticotropin (ACTH) test offers the possibility of unmasking adrenal dysfunction, which might remain undiscovered using the ACTH test with the standard 250-microg dose. Furthermore, the choice of renal replacement therapy (either hemodialysis or continuous ambulatory peritoneal dialysis [CAPD]) might have an impact on adrenal function. To investigate these possibilities, ACTH tests were performed with three different doses (ie, 1, 5, and 250 microg) in 14 CRF patients and in seven healthy controls. Seven of the CRF patients were receiving chronic hemodialysis and seven were receiving CAPD. Basal plasma concentrations of cortisol were comparable in the three groups tested (5.3+/-0.4 microg/dL in the controls, 6.6+/-0.7 microg/dL in the hemodialysis patients, and 7.9+/-1.0 microg/dL in the CAPD patients), whereas basal ACTH concentrations were significantly elevated in the CRF patients (28.5+/-3.8 pg/mL in the hemodialysis patients and 33.0+/-6.0 pg/mL in the CAPD patients) when compared with normal controls (17.0+/-1.4 pg/mL; P < 0.05). All three doses of ACTH resulted in a rapid increase of plasma cortisol concentrations that was comparable in all three groups. In the hemodialysis patients, a trend toward a diminished response to the lowest dose of 1 microg was noticed. We conclude, therefore, that adrenal response to ACTH in various doses is unaffected in CRF independent of whether hemodialysis or CAPD is chosen for renal replacement therapy.

Spinal opioid mu receptor expression in lumbar spinal cord of rats following nerve injury

Previous studies in rats have shown that spinal morphine loses potency and efficacy to suppress an acute nociceptive stimulus applied to the tail or the paw following injury to peripheral nerves by tight ligation of the L5/L6 spinal nerves. Additionally, intrathecal (i.th.) morphine is ineffective in suppressing tactile allodynia at fully antinociceptive doses in these animals. The molecular basis for this loss of morphine potency and efficacy in nerve injury states is not known. One possible explanation for this phenomenon is a generalized, multi-segmental loss of opioid mu (mu) receptors in the dorsal horn of the spinal cord after nerve injury. This hypothesis was tested here by determining whether nerve injury produces (a) a decrease in mu receptors in the lumbar spinal cord; (b) a decrease in the affinity of ligand-receptor interaction, (c) a decrease in the fraction of high-affinity state of the mu receptors and (d) a reduced ability of morphine to activate G-proteins via mu receptors. Lumbar spinal cord tissues were examined 7 days after the nerve injury, a time when stable allodynia was observed. At this point, no differences were observed in the receptor density or affinity of [3H]DAMGO (mu selective agonist) or [3H]CTAP (mu selective antagonist) in the dorsal quadrant of lumbar spinal cord ipsilateral to nerve injury. Additionally, no change in morphine's potency and efficacy in activating G-proteins was observed. In contrast, staining for mu opioid receptors using mu-selective antibodies revealed a discrete loss of mu opioid receptors localized ipsilateral to the nerve injury and specific for sections taken at the L6 level. At these spinal segments, mu opioid receptors were decreased in laminae I and II. The data indicate that the loss of mu opioid receptors are highly localized and may contribute to the loss of morphine activity involving input at these spinal segments (e.g., foot-flick response). On the other hand, the lack of a generalized loss of opioid mu receptors across spinal segments makes it unlikely that this is the primary cause for the loss of potency and efficacy of mu opioids to suppress multi-segmental reflexes, such as the tail-flick response.

Effects of parathyroid hormone and serum calcium on the phenotype and function of mononuclear cells in patients with primary hyperparathyroidism

BACKGROUND

Several studies have demonstrated specific influence of parathyroid hormone (PTH) on immune parameters, especially on T- and B-cell function, migration of polymorphonuclear leucocytes (PMNLs) and antibody synthesis, in patients with secondary hyperparathyroidism and chronic renal failure and recently also in patients with primary hyperparathyroidism (pHPT).

METHODS

We therefore examined 12 patients with pHPT before and 6 months after parathyroidectomy (PTX) and nine sex- and age-matched control subjects to determine the impact of PTH and serum calcium concentrations on several immune parameters, including (a) serum concentrations of immunoglobulins, (b) immunophenotype of peripheral blood lymphocytes, (c) phytohaemagglutinin (PHA)-induced lymphocyte proliferation and (d) monocytic surface marker expression.

RESULTS

Serum concentrations of immunoglobulins (IgG, IgA, IgM) were unaffected by elevated serum PTH and calcium levels. T lymphocytes (CD3), B lymphocytes (CD19), NK cells (CD16/56) and monocytes (CD16) revealed a normal distribution and were not different before and after PTX in patients with pHPT when compared with the control group. CD4+ T-helper lymphocytes were significantly elevated pre- and post-operatively in patients with pHPT. The lymphocyte proliferation response to PHA in the highest concentration (12.5 micrograms L-1) tested was significantly suppressed in patients with pHPT preoperatively when compared with the patients post-operatively and the control group. In addition, both CD4+ and CD8+ lymphocytes showed a lower expression of activation markers, interleukin 2 (IL-2) receptor (CD25) and transferrin receptor (CD71), which could be partially restored 6 months after PTX, but did not reach normal values.

CONCLUSION

In summary, in contrast to the findings in patients with secondary HPT, pHPT appears to be associated with less alterations of immune functions. Chronically elevated serum PTH and calcium concentrations in patients with pHPT induce a higher percentage of CD4+ helper T lymphocytes and a suppressed lymphocyte response to PHA as well as a reduced expression of activation markers on peripheral blood lymphocytes.

Role of carboxyl terminus of mu-and delta-opioid receptor in agonist-induced down-regulation

Chronic exposure of mu-and delta-opioid receptors to their agonists leads to different rates in receptor down-regulation. In order to analyze the role of the carboxyl terminus of mu-and delta-opioid receptors in the difference in the rate of down-regulation, two chimeras of these receptors were generated by swapping the carboxyl termini; MORTAGDT and DORTAGMT. These chimeras were tagged at the N-terminus with hemagglutinin (HA) epitope (YPYDVPDYA), which can be recognized by the monoclonal antibody 12CA5, and then stably expressed in Neuro 2A (N2A) cells. The swapping of the carboxyl termini did not alter the ligand selectivity of these receptor chimeras. However, they did exhibit a reduction in agonist potency to inhibit forskolin-stimulated adenylyl cyclase activity for all agonists tested except etorphine which had a potency comparable to that of wild type receptors. Treatment of the N2A cells expressing MORTAGDT with 50 nM etorphine produced a faster rate of receptor down-regulation when compared to the wild type mu-opioid receptor. Immunofluorescence microscopy of the MORTAGDT chimera using a monoclonal antibody against HA confirmed internalization of the receptors after treatment with etorphine for 1 and 6h. There was a reduction in the HA-immunoreactivity at the cell surface of the MORTAGDT chimera concurrent with more noticeable HA-immunoreactivity inside the cell compared to the wild type receptor. On the other hand, the rate of down-regulation of DORTAGMT receptors was seen to be the same as the wild type delta-opioid receptor after etorphine treatment. Immunofluorescence studies showed more reduction in cell surface staining of the DORTAGMT chimera compared to the wild type receptor. These data suggest the involvement of the carboxyl terminus in agonist-induced down-regulation and internalization of the nu-opioid receptor. However, different mechanisms that are unrelated to the carboxyl terminus may operate in the down-regulation of delta-opioid receptor.

Effect of long-term growth-hormone substitution therapy on bone mineral density and parameters of bone metabolism in adult patients with growth hormone deficiency

Reduced bone mineral density (BMD) and the prevalence for osteoporotic vertebral fractures are symptoms of growth hormone deficiency (GHD) syndrome, and GH replacement therapy is now available for GH-deficient adults. We investigated the long-term effects of GH replacement therapy on bone mineral density (BMD) and bone metabolism in 19 adult patients with GHD over a period of 18 months. In response to GH treatment, the initially decreased IGF-I concentrations rose significantly during 18 months of therapy to levels within the normal range (matched for sex and age) (mean change 158.1 +/- 50.8 ng/ml, P < 0.001). Parameters of bone formation such as osteocalcin (OC) and procollagen I-C-Peptide (PICP) showed a significant increase in the first 6 months of therapy, followed by a slight decrease in the next months. Markers of bone resorption (CrosslapsR and deoxypyridinoline (D-Pyr) also increased significantly with a peak value after 6 months and all parameters except PICP remained above baseline values after 18 months. BMD of the femoral neck (FN) showed an increase after 18 months of therapy (mean change 0.01 +/- 0.03 g/cm2 after 18 months, n.s.). However, the increase in BMD was significant only in the lumbar spine (LS) (mean change 0.03 +/- 0.04 g/cm2, P < 0.05 after 18 months). We conclude that GH replacement therapy in adult patients with GHD over a period of 18 months causes a pronounced increase in bone turnover mainly during the first 12 months of therapy and increases BMD of the lumbar spine and the femoral neck after 18 months.

End of life decisions in amyotrophic lateral sclerosis: a cross-cultural perspective

In an era where life-sustaining technology offers physicians unprecedented powers to prolong survival in terminal illness, the question of how end of life decisions are made has become a major subject of study and debate. Amyotrophic lateral sclerosis (ALS) is a disease in which physical ability declines while mental capacity most often remains intact. Since most patients with ALS die of respiratory failure, a distinguishing feature of this disease is whether a patient is offered and accepts a chance to go on long-term mechanical ventilation. This unusual feature makes ALS a compelling model for studying end of life decisions in different countries. This paper reviews the literature and presents preliminary data on how end of life decisions in ALS are made in the US, Great Britain, and Japan. We address this issue by examining how cultural differences in truth-telling and informed consent, societal differences in attitudes toward the use of artificial life support, and legal differences in the role and status of advance directives in each country influenced decisions in the following three groups of patients: (1) the mentally competent; (2) mentally incompetent patients who previously completed advance directives when competent; and (3) mentally incompetent patients who have not provided advance guidance about their wishes.

Effect of elevated serum prolactin concentrations on the immunophenotype of human lymphocytes, mitogen-induced proliferation and phagocytic activity of polymorphonuclear cells

It has been suggested that the immune system is an important target tissue of prolactin (PRL). We therefore investigated several immune parameters in nine patients with chronically elevated serum prolactin concentrations. The immunophenotype of lymphocytes, mitogen-induced lymphocyte proliferation and phagocytic activity of polymorphonuclear cells were determined under high serum prolactin levels and 2 weeks after treatment with dopamine agonists. An increased CD4/CD8 ratio in the hyperprolactinaemic patients could be detected compared with healthy control subjects, which remained high after treatment and did not seem to correlate with serum prolactin concentrations. Peripheral blood B lymphocytes showed an increased expression of CD69 in the treated group but not in untreated patients compared with healthy control subjects. Interleukin 2 receptor, CD45RO, transferrin receptor or HLA-DR expression of CD4 or CD8 cells, as well as oxidative burst and phagocytic activity of granulocytes, were not affected in the patients with prolactinomas. Lymphocyte transformation response to phytohaemagglutinin in vitro was found not to be influenced by elevated prolactin levels except at the highest mitogen concentration tested. These data together with previous reports suggest that, although PRL is required for lymphocyte maturation to achieve normal immune function, elevated PRL levels do not lead to an 'overstimulation' of the immune system in men.

Effect of successful parathyroidectomy on hematopoietic progenitor cells and parameters of red blood cells in patients with primary hyperparathyroidism

Elevated levels of parathyroid hormone (PTH) in primary and secondary hyperparathyroidism inhibit hematopoiesis at the level of hematopoietic progenitor cells, mainly the burst forming units-erythroid (BFUe). Removal of parathyroid adenomas is associated with an increase in hematopoietic progenitor cells. In contrast, a certain amount of PTH and calcium is needed to correct anemia after bleeding demonstrating that PTH has also a stimulatory effect on the bone marrow. We examined the effect of parathyroidectomy (PTX) in 10 patients with histologically proven primary hyperparathyroidism on hematopoietic progenitor cells and several parameters of red blood cells before and at 5, 30 and 90 days after PTX. After successful surgery serum levels of iPTH (p < 0.01) and calcium (p < 0.001) decreased significantly. Subsequently a steady increase in all hematopoietic progenitor cell classes was observed reaching significance for BFUe only (p < 0.05). Red blood cells and hemoglobin reached nearly pretreatment values within 90 days after PTX after they had decreased due to surgery associated blood loss. 8 patients undergoing hemithyroidectomy without PTX showed a similar decrease in red blood cells and hemoglobin followed by a rise after the operation. The changes of these parameters did not differ significantly from the patients with pHPT. In contrast to the patients with pHPT, no changes in hematopoietic progenitor cells during the 90 days were observed. The presented data provide further evidence that increased PTH concentrations might inhibit hematopoiesis in humans in vivo. The inhibition can be reversed following PTX by normalisation of PTH concentrations.

The long-acting dopamine agonist bromocriptine mesylate as additive immunosuppressive drug after kidney transplantation

BACKGROUND

Acute rejection is an important risk factor for kidney graft loss. As evidence suggests that prolactin has important immunostimulatory properties, we conducted a randomized, prospective open trial in which bromocriptine, a drug suppressing prolactin secretion, was administered as an additive immunosuppressive drug after first cadaver kidney transplantation.

METHODS

In the treatment group bromocriptine was given intramuscularly to 22 patients after their first kidney transplantation along with conventional immunosuppression (cyclosporin A, glucocorticoids). Twenty-three patients receiving only conventional immunosuppression served as control subjects. The incidence of acute graft rejections, graft losses, and infections was evaluated.

RESULTS

Serum prolactin concentrations were slightly elevated above normal values before transplantation (32 +/- 5.3 ng/ml) and decreased to values between 13 and 16 ng/ml in the control group and were totally suppressed in the bromocriptine group. After 6 months of follow-up overall patient and allograft survival was 97.7% and 91% respectively. Acute rejection episodes occurred in 31 patients (77.5%): 15 in the bromocriptine group vs 20 in the control group (n.s.). In each group eight patients experienced a cytomegalovirus infection. The incidence of severe bacterial infections (i.e. pneumonia and sepsis) was five and six respectively. The necessity of haemodialysis after transplantation was 3.1% in the patients on bromocriptine and 23% in those without.

CONCLUSIONS

Suppression of circulating prolactin concentration by bromocriptine did not improve the clinical outcome of patients after kidney transplantation receiving cyclosporin and prednisolone.

Vesicular acetylcholine transporter (VAChT) protein: a novel and unique marker for cholinergic neurons in the central and peripheral nervous systems

Acetylcholine (ACh) is synthesized in nerve terminals from choline and acetyl coenzyme A by the cytoplasmic enzyme choline acetyltransferase (ChAT). The neurotransmitter is thereafter transported into synaptic vesicles, where it is stored until release. cDNA clones encoding a vesicular ACh transporter (VAChT) were recently isolated. In this paper, we report on the generation of highly specific goat polyclonal antisera to the rat VAChT protein by using a synthetic carboxy-terminal 20-amino-acid peptide sequence as an immunogen. Characterization of the antisera revealed recognition of VAChT, but not vesicular monoamine transporter (VMAT) protein, in transfected CV-1 cells. VAChT immunoreactivity was also detected in cells that endogenously express the protein, such as in PC12 cells and in primary cultures of spinal motoneurons. Absorption controls showed that the VAChT antisera could be completely blocked at the 10(-5) M concentration by cognate peptide used for immunization. The antisera cross-reacted with the VAChT protein in rat and mouse but not in guinea pig, rabbit, or cat. Immunohistochemistry and confocal laser microscopy, using the goat VAChT antisera, showed strong immunoreactivity in discrete fibers and neuronal cell bodies of the central and peripheral nervous systems. Within cell bodies and axonal nerve terminals, as well as in dendrites, the staining appeared granular, presumably representing labeling of synaptic vesicles containing ACh. In the rat central nervous system, VAChT-positive cell bodies were demonstrated in the cerebral cortex, striatum, septum, nucleus basalis, medial habenula, mesopontine complex, cranial, and autonomic and spinal motor nuclei and in the intermediomedial region near the central canal. High densities of VAChT-immunoreactive axonal fibers were encountered in areas such as the olfactory bulb, cerebral cortex, striatum, basal forebrain, amygdala, thalamus, hypothalamus including median eminence, hippocampal formation, superior colliculus, interpeduncular nucleus, and pedunculopontine and laterodorsal tegmental nuclei. In cranial and spinal motor nuclei, particularly large varicosities were seen in close proximity to the motoneuron cell somata and their proximal dendrites. In the peripheral nervous system, VAChT immunoreactivity was also detected in motor endplates of skeletal muscle as well as in fibers of sympathetic and parasympathetic abdominal ganglia, heart atrium, respiratory tract, gastrointestinal tract, pancreas, adrenal medulla, male genitourinary tract, and salivary and lacrimal glands. Direct double labeling revealed colocalization of VAChT and ChAT immunoreactivity in neurons. The results show that VAChT antisera represent novel and unique tools for the study of cholinergic neurons in the central and peripheral nervous systems.