Tina Kienitz

Testosterone and Blood Pressure Regulation

Background: There is substantial evidence that androgens may play a role in determining sex-specific blood pressure. Men are at higher risk for developing coronary heart disease or hypertension compared to premenopausal women. However, effects of androgens on the renal and cardiovascular system are complex. This review provides a critical overview of testosterone actions. Methods: We searched Pubmed library for experimental, animal and clinical studies, using the keywords ‘blood pressure’, ‘hypertension’, ‘testosterone’ and ‘androgens’. Results: While acute administration of testosterone seems to decrease vascular tone, the long-term net effect of androgens appears to be vasoconstriction via upregulation of thromboxane A2 expression, norepinephrine synthesis, angiotensin II expression, and endothelin-1 action. Furthermore, androgens cause cardiac hypertrophy, promote atherosclerosis, vascular remodelling and stimulate renal prohypertensive processes involving the renin-angiotensin-aldosterone system. Androgens seem to promote oxidative stress in the kidney and may also play a role in the differentiation of brain areas involved in blood pressure regulation. Conclusion: The effects of sex steroids on different parts of the renal-vascular system are complex and often contradictory. In sum, net effects of androgen action seem to be vasoconstriction, atherosclerosis and stimulation of the renin-angiotensin-aldosterone system. Therefore, androgens may determine blood pressure and the prevalence of cardiovascular disease.

Long-term management in five cases of TSH-secreting pituitary adenomas: a single center study and review of the literature

OBJECTIVE TSH-secreting pituitary tumors (TSH-omas) are a rare cause of hyperthyroidism and account for <1% of all pituitary adenomas. Failure to recognize the presence of a TSH-oma may result in dramatic consequences such as thyroid ablation that may cause further growth in pituitary tumor. The primary goal of the treatment of TSH-omas is to remove the pituitary tumor. Medical treatment includes dopaminergic agonists or somatostatin analogs. METHODS AND RESULTS We report five cases of TSH-oma diagnosed between 1997 and 2006 and review the literature. All the patients are females with an age range from 54 to 65 years at diagnosis. Four of the five patients had at least one event of thyroid surgery due to goiter or nodule of unknown dignity. Three of the five patients had a stroke before the diagnosis of TSH-oma, probably due to hypertension, or smoking and contraceptive treatment. One patient with invasive tumor growth received stereotactic radiotherapy (and developed panhypopituitarism after operation), another patient received somatostatin analogs preoperatively and successfully underwent transsphenoidal operation. Three of the five patients received dopaminergic agonists (bromocriptine 5 mg daily or cabergoline 0.5-0.75 mg per week), because they refused surgical therapy or the tumor was stable under dopaminergic therapy. All patients have been followed-up for 2.5-8 years. A normalization of circulating thyroid hormone levels was achieved in all patients. The patient who underwent operation shows no recurrence of the disease. The other patients have a stable pituitary mass without signs of growth. CONCLUSION We report the successful long-term treatment of TSH-omas with different therapies.

Renal TLR4 mRNA Expression Correlates with Inflammatory Marker MCP-1 and Profibrotic Molecule TGF-β1 in Patients with Chronic Kidney Disease

Background: Toll-like receptor-4 (TLR4) has been implicated in the pathogenesis of different renal diseases in rodent models. However, in human kidney disease, TLR4 expression and regulation is not well understood. We hypothesized that renal TLR4 expression plays a role in chronic kidney disease (CKD) and is associated with proteinuria, kidney function, histological diagnosis, and inflammatory mediators. Methods: We quantified TLR4 mRNA as well as expression of macrophage chemoattractant protein-1 (MCP-1), transforming growth factor-β1 (TGF-β1) and interleukin-6 (IL-6) in human kidney biopsies from 70 patients with CKD. We measured kidney function, urinary MCP-1 protein excretion, and the amount of chronic damage. Macrophage load was quantified by CD68 and vascularization by CD34 immunostaining. Results: TLR4 expression correlated significantly with MCP-1 and TGF-β1 expression. High TLR4 expression was associated with high IL-6 expression. TLR4 expression was significantly upregulated in patients with severe proteinuria, and in patients with chronic ischemic renal damage and IgA nephropathy, when compared to patients with thin glomerular basement membrane disease. TLR4 expression did not correlate with creatinine clearance, renal outcome, macrophage load or chronic damage. Conclusions: We show for the first time that renal TLR4 expression was significantly associated with the pro-inflammatory marker MCP-1 and the profibrotic molecule TGF-β1 in kidney biopsies from patients with CKD, suggesting that increased expression of TLR4 is an important feature of CKD.

Hepatic 11beta-HSD1 mRNA expression in fatty liver and nonalcoholic steatohepatitis

Context  Nonalcoholic fatty liver disease represents the hepatic manifestation of the metabolic syndrome. Nonalcoholic steatohepatitis (NASH) is the progressive form of liver injury. The pathophysiology that leads to NASH is not well understood.

Sex-specific regulation of ENaC and androgen receptor in female rat kidney.

With the beginning of puberty blood pressure increases and is persistently higher in men than in premenopausal women. Sex steroids are known to have complex effects on the renal and cardiovascular system and are involved in blood pressure regulation. The epithelial sodium channel (ENaC) modulates sodium reabsorption in the kidney, but little is known about sex-specific regulation of ENaC subunit expression. Regulation of the androgen receptor (AR) is known to be tissue-specific and age-dependent, but not well studied in the kidney. We investigated the effects of sex steroids on ENaC subunits and renal AR expression in an in vivo rat model. Ovariectomized female Wistar rats were treated with placebo, testosterone, 5 alpha-dihydrotestosterone (DHT) or 17 beta-estradiol (E2) for 14 days, and quantitative PCR and Western immunoblots were performed. DHT significantly decreased expression of all ENaC subunits in female rats, whereas testosterone showed only a trend to lower ENaC expression. These results are in contrast to previous studies where stimulating effects of androgens on the alpha-subunit of ENaC were seen. AR mRNA expression showed a trend to lower levels in females after testosterone treatment in this study. However, estrogen treatment significantly downregulated AR mRNA expression. In male control animals we were able to show a significantly increased expression of AR mRNA upon testosterone treatment. Our data demonstrate that AR and ENaC are regulated by sex steroids. That way sex steroids might modulate renal sodium reabsorption and therefore provide a possible explanation for sex differences in blood pressure.

Novel PHEX nonsense mutation in a patient with X-linked hypophosphatemic rickets and review of current therapeutic regimens.

INTRODUCTION The most common form of familial hypophosphatemic rickets is X-linked. PHEX has been identified as the gene defective in this phosphate wasting disorder leading to decreased renal phosphate reabsorption, hypophosphatemia and inappropriate concentrations of 1,25-dihydroxyvitamin D in regard to hypophosphatemia. Clinical manifestation are skeletal deformities, short stature, osteomalacia, dental abscesses, bone pain, and loss of hearing. SUBJECTS AND METHODS We report 3 cases of hypophosphatemic rickets with genetic mutational analysis of the PHEX gene. In 1 male patient an unknown nonsense mutation was found in exon 7, codon 245 (c.735T>G, Tyr245Term, Y245X). In both female patients known mutations were found: c.682delTC (exon 6, codon 228) and c.1952G>C (exon 19, codon 651, R651P). Age at diagnosis ranged from early childhood to the age of 35 years. Clinical complications were hip replacement in 1 patient, mild nephrocalcinosis in 2 patients and loss of hearing in 1 patient. All 3 patients have been treated with phosphate supplements and receive 1,25-dihydroxyvitamin D. Under this regimen all patients show stable biochemical markers with slight hyperparathyreoidism. In all patients at least one family member is affected by rickets, as well. CONCLUSIONS We report a novel nonsense mutation of PHEX that has not been identified so far. The recent discovery of FGF23 and MEPE has changed our understanding of the kidney-bone metabolism, but also raises concerns about the efficacy of current therapeutic regimens that are reviewed in this context.

Sex-specific effects of spironolactone on blood pressure in gonadectomized male and female Wistar rats.

A low-salt diet is known to decrease and salt excess to increase blood pressure in humans and rodents. Sex steroids seem to play a role in salt dependent hypertension. However, little is known about sex differences in mineralocorticoid receptor blockade between male and female rats. The objective of the work was at first to investigate the effects of a low-salt vs. a high-salt diet on blood pressure without the influence of gonadal steroids in male and female rats. Second, to determine the sex-specific effects of mineralocorticoid receptor blockade by spironolactone in high-salt and low-salt fed gonadectomized male and female animals. Normotensive male and female Wistar rats were gonadectomized and put on a low (NaCl<0.03%) or high (NaCl=4%) salt diet. On each diet animals received spironolactone or placebo. Blood pressure was measured by tail-cuff-method; 24-h urine samples were collected in metabolic cages and blood was collected for hormonal measurements. High-salt diet significantly increased systolic blood pressure in both sexes. This effect could be blocked effectively by spironolactone only in male rats. Spironolactone treatment significantly increased aldosterone levels in males and females independent of the sodium content of the diet. High sodium diet significantly increased relative kidney weight, which was not altered by spironolactone treatment. Independently of gonadal steroids a high-salt diet increased blood pressure in gonadectomized male and female rats. Spironolactone lowered blood pressure only in male not in female rats on a high-salt diet clearly indicating sex-specific effects of the mineralo-corticoid antagonist spironolactone.

Flutamide increases aldosterone levels in gonadectomized male but not female Wistar rats.

BACKGROUND Sex-specific differences in blood pressure (BP) suggest an important modulating role of testosterone in the kidney. However, little is known about the interaction between androgens and the mineralocorticoid aldosterone. Our objective was to determine the effects of testosterone in gonadectomized male and female rats on a low-salt diet, and to determine the effect of androgen receptor (AR) blockade by flutamide on BP and on aldosterone levels. METHODS Normotensive male and female Wistar rats were gonadectomized and put on a low-salt diet. They were treated for 16 days with testosterone or placebo. In addition, the animals received the AR antagonist flutamide or placebo, respectively. BP was measured by tail-cuff method, 24-h urine samples were collected in metabolic cages and blood was collected for hormonal measurements. RESULTS Testosterone increased BP in males and females, and this effect could be blocked by flutamide. Flutamide treatment itself significantly increased aldosterone levels in male but not in female rats. These elevated aldosterone levels could be lowered by testosterone treatment during AR blockade. Accordingly to aldosterone levels, flutamide increased in males the serum sodium/potassium to urinary sodium/potassium ratio, an in vivo indicator of renal aldosterone action. CONCLUSIONS Testosterone regulates BP in male and female gonadectomized rats via the AR. Flutamide by itself exerts influence over aldosterone in the absence of gonadal steroid replacement suggesting AR involvement in renal sodium handling. These flutamide effects were sex-specific and not seen in female rats.

Downregulation of hepatic glucose-6-phosphatase-α in patients with hepatic steatosis.

Glucose‐6‐phosphate transporter (G6PT) and microsomal glucose‐6‐phosphatase‐α (G6Pase‐α) perform the terminal step in glycogenolysis and gluconeogenesis. Deficiency of these proteins leads to glycogen storage diseases. Partial inhibition of G6Pase in rats results in increased hepatic triglyceride content and de novo lipogenesis leading to hepatic steatosis. Hepatic steatosis represents hepatic manifestation of the metabolic syndrome. We investigated molecular mechanisms that may explain the relationship between fatty liver and G6Pase‐α in humans in detail. A total of 27 patients (11 men, 16 women) underwent liver biopsy. Histological diagnosis identified nonfatty liver in seven patients and nonalcoholic fatty liver in 20 patients. We quantified G6Pase‐α and G6PT mRNA expression by real‐time PCR. Anthropometric measurements and analysis of plasma lipids and liver enzymes were performed. Patients with fatty liver showed no significant differences in age, HOMAIR (homeostasis model assessment of insulin resistance), BMI, liver enzymes or waist‐to‐hip ratio compared to those with nonfatty liver, but total plasma cholesterol levels and liver fat content were higher in patients with fatty liver (P < 0.05). G6Pase‐α and G6PT mRNA expressions were significantly downregulated in fatty compared to histologically normal liver (P < 0.05). G6Pase‐α and G6PT mRNA expressions correlated positively (R2 = 0.406 P < 0.05). Both expressions did not correlate with age, BMI, aspartate transaminase, alanine transaminase, alkaline phosphatase, γ‐glutamyl transferase, triglycerides or glucose levels. Our data suggest that expression of hepatic G6Pase‐α and G6PT are closely interlinked. Downregulation of G6Pase‐α in fatty liver might be associated with hepatic fat accumulation and pathogenesis of hepatic steatosis.

Palliative treatment of uncontrollable hypercalcemia due to parathyrotoxicosis: denosumab as rescue therapy

Parathyroid carcinoma is a rare disease leading to severe hypercalcemia due to hyperparathyroidism. Surgery is the primary treatment option. A more progressive form of the disease is characterized by parathyrotoxicosis, and subsequent hypercalcemia is the most common cause of death. We report a case presenting with severe hypercalcemia due to parathyrotoxicosis from parathyroid carcinoma treated for the first time using the monoclonal antibody denosumab as a rescue therapy and present long-term follow-up data. The 71-year-old patient presented with severe hypercalcemia due to metastatic parathyroid carcinoma. Despite undergoing treatment with bisphosphonates, cinacalcet hydrochloride, and forced diuresis, the patient`s condition deteriorated rapidly due to resistant hypercalcemia. Surgery performed because of spinal metastasis and forced diuresis lowered calcium levels, albeit they remained in the hypercalcemic range and significantly increased when forced diuresis was stopped. Considering a palliative situation to overcome hypercalcemia, we decided to administer denosumab, a monoclonal antibody that binds to the receptor activator of nuclear factor-kappa B ligand. After a single subcutaneous administration of 60 mg denosumab, calcium levels normalized within one day. Subsequent denosumab injections led to permanent control of serum calcium for more than 2 years despite rising parathyroid hormone levels and repeated surgeries. Together with recent cases in the literature supporting our observation, we believe that denosumab is relevant for future trials and represents an effective tool to control hypercalcemia in patients with advanced stages of parathyroid cancer. Learning points Severe hypercalcemia is the most common cause of death in patients with parathyroid carcinoma. The monoclonal antibody denosumab rapidly lowered severely elevated serum calcium levels due to parathyrotoxicosis. Denosumab was effective in the long-term treatment of hypercalcemia despite progression of parathyroid carcinoma.