Venous endothelial function in postmenopausal women after six months of tibolone therapy

STUDY OBJECTIVE

To test venous endothelial function in long-term climateric therapy with tibolone.

DESIGN

Measurement of dorsal hand-vein diameter by venous occlusion plethysmography during infusion of norepinephrine (NE), bradykinin (BK), NG-monomethyl L-arginine (L-NMMA) and sodium nitroprusside (SNP).

SETTING

Plethysmography and Menopause Units. University Hospital Valdecilla. Santander. Spain.

PATIENTS

Eleven postmenopausal women having continuous treatment with oral tibolone (2.5 mg/day) for 6 months.

INTERVENTIONS

Three plethysmography studies were made: at baseline, and at three and six months of treatment.

MAIN OUTCOME MEASURES

Dorsal hand-vein diameter measured by venous occlusion plethysmography during infusion of NE, BK, L-NMMA and SNP.

RESULTS

(a) Baseline study: maximum dilation with BK was 54.2+/-10.2%. (b) Three-month study: BK dilation of 71.5+/-11.9%, with a significant increase of 17.3% (P=0.019) compared with baseline. (c) Six-month study: BK dilation of 77.5+/-11.9%, with a significant increase 23.3% (P=0.002) compared with baseline. Maximal vasodilation was reached with SNP in the three studies and L-NMMA infusion has a similar vasoconstrictor response in the three studies.

CONCLUSIONS

Long-term climateric therapy with tibolone improves vein endothelium-dependent vasodilation suggesting a positive impact of this drug on endothelial function.

Effects of long-term treatment with antipsychotics on serum leptin levels

BACKGROUND

Abnormal regulation of the adipocyte-derived hormone leptin could play a role in body weight gain induced by antipsychotics.

AIMS

To study the effects of long-term antipsychotic treatment on leptin levels in patients with schizophrenia.

METHOD

Serum leptin levels were determined in 59 out-patients with chronic schizophrenia and in the same number of healthy subjects controlled by gender, age and body mass index.

RESULTS

Leptin levels did not differ between patients and controls. Leptin levels in patients with schizophrenia correlated with weight gain, even after controlling for current weight, but did not show any association with clinical variables. Antipsychotic class tended to exert different effects over leptin levels (among atypicals, olanzapine induced a greater increase).

CONCLUSIONS

Elevation of leptin levels induced by chronic antipsychotic treatment can be attributed to weight gain, but other mechanisms could be involved.

Perioperative response of leptin and the tumor necrosis factor alpha system in morbidly obese patients. Influence of cortisol inhibition by etomidate

BACKGROUND

Leptin, tumor necrosis factor alpha (TNFalpha) and soluble TNFalpha receptors are secreted by the adipose tissue. Surgery induces a complex cytokine and neurohormonal response. The aim of our study was to investigate the perioperative response of leptin and the TNFalpha system in morbidly obese patients submitted to gastroplasty, and the possible involvement of cortisol in their responses.

METHODS

Serum cortisol, adrenocorticotropic hormone (ACTH), leptin, TNFalpha and soluble TNFalpha receptor I were measured in 22 morbidly obese women (11 anesthetized with thiopental and 11 with etomidate, a well known inhibitor of cortisol synthesis). Samples were collected before anesthesia induction, just before surgical incision, and 2, 4, 6, 12, 24 and 48 h after the start of surgery.

RESULTS

Baseline serum leptin correlated with body mass index (r=0.567, P=0.007). Baseline serum leptin and TNFalpha were higher than normal. Cortisol release was inhibited in the etomidate group with a subsequent higher stimulation of ACTH release. A statistically significant decrease in serum leptin levels was observed in both groups at 2, 4, 6 and 48 h, compared with basal values. A similar decrease in serum TNFalpha levels was observed in both groups, but the decrease reached significance only in the etomidate group. Serum soluble TNFalpha receptor I did not decrease. No differences were found between the two groups in leptin, TNFalpha or soluble TNFalpha receptor I concentrations at any time.

CONCLUSION

Serum leptin and TNFalpha levels decrease in obese patients during gastroplasty. Transitory inhibition of cortisol release does not alter this response.

Increased bone remodeling in first-episode major depressive disorder

OBJECTIVE

Bone mineral density is decreased in patients with depressive disorder. This study evaluated biochemical bone remodeling markers in patients having their first depressive episode who had not taken psychotropic medications to evaluate possible pathogenic mechanisms implicated in the loss of bone mineral density in early states of this illness.

METHODS

Serum osteocalcin, parathyroid hormone, bone alkaline phosphatase, telopeptide, collagen type I C-terminal propeptide, cross-laps, and 25-hydroxyvitamin D levels were measured in 19 depressive patients and 19 age-matched healthy women. In addition, serum cortisol and interleukin-6 were determined. Patients were assessed with the Schedules for Clinical Assessment in Neuropsychiatry interview and met criteria for a single depressive episode.

RESULTS

Depressed patients had increased levels of osteocalcin (p = .003), an osteoblastic marker; telopeptide (p = .01), an osteoclastic marker; and cross-laps (p = .000), another osteoclastic marker. Parathyroid hormone was lower in patients (p = .02), whereas the rest of the markers were comparable between patients and healthy control subjects. Serum cortisol was higher in depressed patients than in control subjects (p = .003), but cortisolemia and interleukin-6 did not show any relationship with bone markers in patients. Clinical severity of the illness and weight loss due to depression in patients did not correlate with bone remodeling markers.

CONCLUSIONS

These data suggest that an increase in bone remodeling not due to vitamin D deficiency induces a release of calcium from bone and inhibition of parathyroid hormone secretion.

Expression of opioid receptors in osteoblast-like MG-63 cells, and effects of different opioid agonists on alkaline phosphatase and osteocalcin secretion by these cells

We have previously shown that several stressful situations associated with tissue injury determine a decrease in serum osteocalcin concentration. Since reduced osteocalcin production is a marker of decreased osteoblastic activity, this finding could be related to the pathogenesis of osteoporosis secondary to some diseases. Endogenous opioids are involved in stress response. Proenkephalin-derived peptides have been shown to inhibit alkaline phosphatase activity, another marker of bone formation, in the murine cell line ROS-17/2.8. On the other hand, serum osteocalcin has been reported as being low in heroin abusers. We have therefore thought it of interest to study the presence of opioid receptors in the human osteoblast-like cell line MG-63, and to evaluate the effects of different opioid agonists on the secretion of alkaline phosphatase and osteocalcin by these cells. The presence of opioid receptors was studied by means of RT-PCR and immunohistochemistry. RT-PCR studies suggested the presence of specific mRNA for the three types of receptors, and immunohistochemistry clearly showed their occurrence. Osteocalcin synthesis was significantly inhibited by high concentrations of the mu agonists morphine and (D-Ala(2), N-MePhe(4),Gly(5)-ol)-enkephalin although no changes were seen with the delta agonist (D-Ala(2),D-leu(5))-enkephalin. Morphine-induced osteocalcin inhibition was abolished when osteoblastic cells were incubated simultaneously with naloxone, whereas it was potentiated when cells were preincubated with naloxone. None of the opioid agonists modified the secretion of alkaline phosphatase. In conclusion, human osteoblast-like cells MG-63 express the three types of opioid receptors. Endogenous opioids may be involved in the reduction of osteocalcin observed in stressful situations associated with tissue injury.

Venous endothelial function in postmenopausal women who are receiving long-term estrogen and progestagen therapy

OBJECTIVE

To test venous endothelial function during long-term hormone replacement therapy (HRT) and after treatment withdrawal.

DESIGN

Measurement of dorsal hand-vein diameter by venous occlusion plethysmography during infusion of norepinephrine, bradykinin, NG-monomethyl L-arginine, and sodium nitroprusside.

SETTING

Plethysmography and menopause units, University Hospital Marqués de Valdecilla, Santander, Spain.

PATIENT(S)

Twenty postmenopausal women, of whom 10 were assigned to receive no hormone replacement therapy (HRT) for 6 months after plethysmography (group A) and 10 were assigned to receive HRT for 6 months (group B). After 6 months, HRT was administered to group A and withdrawn from group B for another 6 months.

INTERVENTION(S)

Plethysmography at baseline and at 6 and 12 months.

MAIN OUTCOME MEASURE(S)

Dorsal hand-vein diameter measured by venous occlusion plethysmography during infusion of norepinephrine, bradykinin, NG-monomethyl L-arginine, or sodium nitroprusside.

RESULT(S)

At 6 months, the maximum dilation obtained with bradykinin was 48.8 +/- 7.58% in group A and 76.7 +/- 12.9% in group B. At 12 months, maximum bradykinin dilation increased to 74.3 +/- 14.2% in group A and decreased to 54.0 +/- 15.9% in group B.

CONCLUSION(S)

Long-term HRT with estrogen plus progestin improves endothelium-dependent vasodilation, but this effect is lost in a relatively short time. Endothelial function in dorsal hand veins is an easy-to-use plethysmography model that can be used in serial studies.

[Perfusion SPECT with (99m)Tc-HMPAO in type I diabetics with no background of central neurologic symptoms. A study of activation with acetazolamide]

OBJECTIVE

This study aimed to assess if activation with acetazolamide increases the diagnostic capacity of baseline SPECT with (99m)Tc-HMPAO in the study of brain perfusion in type I diabetic patients with no history of neurological symptoms.

MATERIAL AND METHODS

A baseline SPECT was carried out in 11 diabetes mellitus type I patients with no neurological symptoms with 555 MBq of (99m)Tc-HMPAO; 1 g of acetazolamide was administered during the examination and a second SPECT was obtained 20' later with the same methodology used in the baseline SPECT. The images were visually analyzed. The post-acetazolamide studies were analyzed with (CBS) and without (WBS) baseline image subtraction and both methods were compared.

RESULTS

The baseline SPECT showed 48 hypoperfused cortical areas. The post-acetazolamide SPECT analyzed without baseline image subtraction detected 14 new hypoperfused areas and those analyzed with it detected 26 areas. 69% of the baseline hypoperfused areas were hyporeactive in the WBS analysis and 54% in the CBS analysis.

CONCLUSION

The perfusion SPECT with acetazolamide improves the diagnostic capacity of the baseline perfusion (99m)Tc-HMPAO SPECT, and makes it possible to classify the abnormalities as metabolic or vascular, with a preference for the post-acetazolamide CBS imaging analysis.

Higher levels of serum copper in schizophrenic patients treated with depot neuroleptics

The findings of previous research on the status of trace elements in patients with schizophrenia have been controversial. We studied 62 outpatients with a DSM-IV diagnosis of schizophrenia, and compared them with sex- and age-matched healthy controls. Serum copper levels were significantly higher in schizophrenic patients (mean 117.4 microg/dl; S.D. 23.4) than in healthy controls (105.6+/-27.9). Those patients on treatment with depot neuroleptics had higher copper levels. Zinc levels did not differ between patients and healthy controls. Altered levels of trace elements in schizophrenic patients may be a consequence of antipsychotic treatment.

Different time course of circulating adhesion molecules and hyaluran during hepatic allograft rejection

BACKGROUND

Inducible adhesion molecules are involved in cell-mediated allograft rejection. In addition, the endothelium is the main target of this process. This study investigated, whether soluble (s) forms of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) are elevated during cellular rejection and whether hyaluran is a useful marker of endothelial function in liver transplantation.

METHODS

Serum levels of sICAM-1, sVCAM-1, and hyaluran were determined in 24 controls and 27 hepatic transplant recipients. These patients were divided in two groups: group I, 14 patients without rejection; and group II, 13 patients with rejection. Samples were collected on day 1 and 7 after transplantation, on the day of liver biopsy, and after treatment of the rejection.

RESULTS

We found a significant increase in sICAM-1 levels in the postoperative period in the rejection group compared with the non rejection group. It persisted significantly elevated until the diagnosis of rejection was made. In contrast, sVCAM-1 was only significantly elevated in the rejection group when diagnosis of rejection was evident. Hyaluran levels were also significantly elevated in the rejection group at diagnosis of rejection. We noticed a significant decline in sICAM-1, sVCAM-1, and hyaluran levels after successful treatment of rejection. In addition, we observed in the non-rejection group a stable lower levels of hyaluran during the entire postoperative period.

CONCLUSIONS

The release of circulating adhesion molecules is a prominent feature coinciding with the first episode of hepatic rejection. Differential patterns of sICAM-1 and sVCAM-1 exist during rejection. In addition, hyaluran levels may be a sensitive marker of liver endothelial cell function in the postoperative period of liver transplantation.

Adrenomedullin in liver transplantation and its relationship with vascular complications

Adrenomedullin (AM) is a potent vasodilating peptide that increases rat platelet cyclic adenosine monophosphate levels and acts on endothelial cells to stimulate nitric oxide release. Both mechanisms inhibit platelet function. Considering these effects, AM may have a role in cardiovascular regulation after orthotopic liver transplantation (OLT) and could have an antithrombotic effect. The aim of the present study is to investigate plasma AM levels in the early postoperative period after OLT and their relationship with vascular complications in OLT. We measured plasma AM levels in 35 patients with cirrhosis who underwent OLT at baseline and 1, 7, and 15 days postoperatively. We found that AM levels were significantly greater in patients with cirrhosis compared with healthy subjects. Of the 35 patients, 10 had vascular complications. In these 10 patients, AM concentrations were significantly greater than those observed in the nonthrombotic group in the early postoperative period. In addition, we also noticed in the nonthrombotic group a significant increase in AM levels from baseline to day 1, then a decrease to baseline levels in the early postoperative period. Our study shows that AM might act as a new humoral factor involved in the response to surgery in OLT and is significantly associated with vascular thrombosis in OLT.

Etidronate inhibits the production of IL-6 by osteoblast-like cells

IL-6 is a resorbing cytokine synthesized by osteoblasts and monocytes that has been implicated in the pathogenesis of osteoporosis. Bisphosphonates are well-known antiresorptive drugs, the antiosteoclastic effect of which has been recently suggested to be brought about at least in part through osteoblasts. Based on these facts, we have studied the effect of etidronate on the production of IL-6 by two tumoral cell lines of human osteoblastic phenotype (MG63 and SaOs cells), and by peripheral blood mononuclear cells (PBMC). For comparison, another antiresorptive drug, estradiol, was included in the study. MG63 cells were stimulated with LPS and IL-1 beta, SaOs cells with LPS, IL-1 beta and PMA, and PBMC with LPS and PMA. Etidronate was tested at 10(-7), 10(-6), 10(-5), and 10(-4) M, and 17beta-estradiol was tested at 10(-10), 10(-9), 10(-8), and 10(-7) M. IL-6 was determined in supernatants by an ELISA. No significant effect of either etidronate or estradiol on IL-6 secretion by LPS or PMA-stimulated PBMC was found. However, in osteoblastic-like cells, an inhibition of IL-6 production by etidronate in LPS-stimulated cultures was found. At the highest concentrations tested, IL-6 production values were 58 +/- 9% and 53 +/- 8% of those at base line for MG63 and SaOs cells, respectively. Estradiol did not modify IL-6 secretion under any condition. In conclusion, our study supports the contention that the antiresorptive effect of bisphosphonates may be due in part to a decrease in IL-6 production by osteoblasts.

Decreased plasma endothelin-1 levels in asymptomatic type I diabetic patients with regional cerebral hypoperfusion assessed by Spect

The prevalence of stroke is increased in diabetic patients. The vasoconstrictor peptide endothelin-1 (ET-1) has been implicated in the development of cerebral vasospasm after stroke but its role in the physiological regulation of cerebral blood flow (CBF) is not well known. Our aim was to assess the relationship between CBF and plasma ET-1 levels in type I diabetic patients. Regional CBF was assessed semi-quantitatively by 99Tc(m)-hexamethylpropylene-amine-oxime (99Tc(m)-HMPAO) single photon emission computed tomography (SPECT) in 50 cerebral "regions of interest" (ROIs) of 19 type I diabetic patients without clinical evidence of cerebral disease, and 10 healthy control subjects. In both groups, plasma ET-1 levels were measured. Results showed that type I diabetic patients had significantly more hypoperfusion ROIs than control subjects. While up to 68.4% of the type I diabetic patients showed 3 or more hypoperfusion ROIs, only 10% of the control subjects did. Plasma ET-1 levels were lower in the type I diabetes subgroup with 3 or more hypoperfusion ROIs than in the type I diabetes subgroup with less than 3 hypoperfusion ROIs and in the control group. Moreover, an inverse correlation between the number of hypoperfusion ROIs and plasma ET-1 levels (r = 0.47, p = 0.04) was found in the type I diabetes group. It is concluded that plasma ET-1 is decreased in type I diabetic patients with subclinical abnormalities of regional CBF assessed by cerebral SPECT. This fact may reflect a compensatory response to the reduction of the brain perfusion in order to prevent ischemic events in these patients.

Patients with poor preoperative ejection fraction have a higher plasma response of adrenomedullin in response to open heart surgery

BACKGROUND

Adrenomedullin (AM) is a potent vasodilator peptide. Plasma AM levels are increased in heart diseases and in sepsis. Heart surgery under cardiopulmonary bypass (CPB) induces a systemic inflammatory response.

METHODS

We measured plasma AM, cAMP (the second messenger of AM), C-reactive protein (CRP) and haemodynamic parameters in 29 patients undergoing elective open heart surgery, before, during and after anaesthesia and CPB as well as on the first morning after surgery.

RESULTS

Basal AM levels were higher than normal and correlated with systolic pulmonary pressure and pulmonary capillary pressure, but not with other haemodynamic parameters. AM increased during CPB and remained elevated 24 h after the start of surgery. Plasma cAMP increased only at the end of CPB. CRP was increased only in the last sample. At the end of CPB and at the end of surgery AM levels were higher in patients with basal ejection fraction<40% compared with those with ejection fraction >60% [456+/-386 vs 252+/-343 (P<0.03) and 832+/-781 vs 391+/-356 pg/ml (P<0.05), respectively].

CONCLUSION

We conclude that AM, as inflammation-related cytokines, increases during and after CPB, that cAMP response is unrelated to AM and that AM response is higher in those patients with worse basal ejection fraction.

Folate levels in psychiatric outpatients

This study examines folate in psychiatric outpatients. Fifty-three outpatients with schizophrenia and 24 outpatients with depressive disorder assessed with the Schedules for Clinical Assessment in Neuropsychiatry interview are included. Patients with schizophrenia had lower serum folate levels than age- and sex-matched controls, while red cell folate levels did not differ. Serum folate levels showed a negative correlation with the Clinical Global Impression, disorganized dimension, and total Positive and Negative Syndrome Scale score. Patients with depressive disorder had lower serum folate levels than healthy controls, but showed no differences in red cell folate levels. Only two patients with schizophrenia had red cell folate levels below the normal range.

[Perioperative response of phosphorus and calcium metabolism and of bone remodeling markers during heart surgery under extracorporeal circulation]

HYPOTHESIS AND OBJECTIVES

Cardiovascular surgery with extracorporeal circulation (ECC) is highly stressful, inducing marked changes in calcium and magnesium homeostasis. Nevertheless, no studies have assessed osteoblastic/osteoclastic activity during and after heart surgery with ECC. Our objective was to analyze changes in serum levels of parameters reflecting phosphorus and calcium metabolism and markers of bone remodelling in this context.

PATIENTS AND METHODS

Changes in serum levels of calcium, phosphorus, whole parathyroid hormone (PTH), magnesium, cortisol, interleukin-6, total alkaline phosphatase, osseous alkaline phosphatase (OAP), osteocalcin, propeptide of type 1 procollagen (PCP1), and carboxyl-terminal telopeptide of type 1 collagen (CTT1) during the 24 perioperative hours in 16 patients undergoing cardiac surgery with ECC.

RESULTS

Total calcium decreased during ECC, triggering acute release of PTH. Osteocalcin decreased at 24 hours in a way that was not accounted for by hemodilution. OAP changes, on the other hand, were consistent with albumin levels and blood cell counts. PCP1 and CTT1 did not change, although correcting for dilution shows that these factors can in fact be considered to have increased.

CONCLUSIONS

The parathyroid gland is activated during ECC. Markers of bone metabolism behave differently over time in response to heart surgery. The data suggest that heart surgery induces discordant responses in various bone cell functions.

Serum interleukin-6 in renal osteodystrophy: relationship with serum PTH and bone remodeling markers

Interleukin-6, synthesized by osteoblasts in response to PTH, stimulates osteoclastogenesis and bone resorption in vitro, and it has been implicated in the pathogenesis of bone loss in several clinical situations. The aim of this study was to evaluate whether serum levels of interleukin-6 were increased in patients with renal osteodystrophy, and to investigate the possible relationships between serum interleukin-6 and PTH levels on one hand, and serum interleukin-6 and bone remodeling markers on the other. Serum interleukin-6 (IL-6), intact PTH, osteocalcin, bone alkaline phosphatase (BAP) and carboxyterminal telopeptide of Type 1 collagen (ICTP) were measured in 86 uremic patients. IL-6 (median [range] 16.5 [1.0-430] pg/ml), PTH (279.8 [11-2004] pg/ml), osteocalcin (143.8 [8-921] ng/ml), BAP (20.9 [6-169] U/I) and ICTP (38.8 [1.5-181.5] microg/l) were higher than normal. IL-6 levels correlated with PTH (r= 0.22, p = 0.04) and with ICTP (r = 0.31, p = 0.004). A stronger correlation was found between PTH and circulating bone remodeling markers (r = 0.66 for osteocalcin, r = 0.56 for BAP, and r = 0.39 for ICTP). The correlation between PTH and IL-6 was stronger in those patients (n = 15) with severe secondary hyperparathyroidism (r= 0,71, p = 0.003). On the other hand, in the group of patients (n = 41) with PTH lower than 250 pg/ml, there was no correlation between IL-6 and PTH, while IL-6 correlated with ICTP (r = 0.44, p = 0.006). Serum IL-6 correlates with ICTP which suggests that it may mediate bone resorption in renal osteodystrophy.

Effect of serum phosphate on parathyroid hormone secretion during hemodialysis

BACKGROUND

Recent studies have demonstrated that a high concentration of phosphate directly stimulates parathyroid hormone (PTH) secretion. High serum levels of phosphate are usually observed in patients with end-stage renal disease. The aim of the present study was to evaluate whether serum phosphate concentration had an acute effect on PTH secretion in hemodialysis patients. The levels of serum phosphate were manipulated during the hemodialysis session by using a phosphate free dialysate or a dialysate with a high content of phosphate.

METHODS

Ten stable hemodialysis patients with PTH values above 300 pg/ml were included in the study. A PTH-calcium curve was obtained during both high phosphate and phosphate free hemodialysis.

RESULTS

The serum phosphate concentration remained high (2.17 +/- 0.18 mM) throughout the high phosphate hemodialysis and decreased progressively to normal levels (1.02 +/- 0.06 mM) during the phosphate free hemodialysis. The serum PTH levels at maximal inhibition by hypercalcemia (minimal PTH) were greater during the high phosphate than the phosphate free hemodialysis (413 +/- 79 vs. 318 +/- 76 pg/ml, P < 0.003). In all patients the values of minimum PTH were greater during the high phosphorus than the phosphorus free hemodialysis. The values of maximally stimulated PTH during hypocalcemia and the set point of the PTH-calcium curve were similar during the high phosphate and the phosphate free hemodialysis.

CONCLUSION

The maintenance of high serum phosphorus levels during hemodialysis prevented, in part, the inhibition of PTH secretion by calcium, which strongly suggests that in hemodialysis patients high serum phosphate contributes directly to the elevation of PTH levels despite normal or high serum calcium concentration.

Age-related responses of vasoactive factors during acute exercise

To evaluate the age-related response of vasoactive factors during acute exercise, young (n = 8, aged 23.6+/-2 years) and old (n = 13, aged 77+/-6 years) healthy volunteers performed a stress test using a treadmill, and blood samples were taken before and after exercise. There were neither basal (old people 77+/-53 vs. young people 67.6+/-40 pg/ml) nor peak exercise-related (old people 77+/-43 vs. young people 66.8+/-34 pg/ml) differences in plasma adrenomedullin (AM) between both groups. AM did not increase with exercise in either group. Regarding plasma cAMP, there were neither basal nor exercise related differences, but this nucleotide increased with exercise in both groups (old people p < 0.0001, young people p < 0.05). Plasma Atrial Natriuretic Peptide (ANP) was higher in basal (116.3+/-64 vs. 46.8+/-21 pg/ml, p < 0.003) and after exercise samples (150.2+/-76.5 vs. 68.7+/-29.5 pg/ml, p < 0.004) in old people as compared with young people. Old people showed an increase in ANP with exercise (p < 0.05), but in young people, though there was a trend to increase, it did not reach statistical significance. There were neither basal nor exercise related differences in plasma cGMP, but this nucleotide increased with exercise in both groups. Angiotensin II (AT-II) levels were lower in basal and after exercise samples in old people as compared with young people. AT-II levels did not increase with exercise in either group. These data suggest that, with increasing age, the vascular tree develops resistance to ANP and higher sensitivity to AT-II, while AM levels do not change. Exercise makes ANP changes more evident, while AM and AT-II are not modified.

1,25-Dihydroxyvitamin D3 receptors in peripheral blood mononuclear cells from patients with renal insufficiency

A reduced expression of the vitamin D receptor (VDR) in parathyroid glands of uremic animals and humans has been observed. Similar results have been obtained by our own group in peripheral blood mononuclear cells (PBMC) from patients with secondary hyperparathyroidism to chronic renal failure. However, the reasons for these changes are not clear. In the present study, we have investigated the specific uptake of [3H]1,25(OH)2D3 by PBMC of 11 women with advanced chronic renal failure (A-CRF), 6 women with mild-moderate renal insufficiency (M-CRF), and 23 healthy women. The mean dissociation constant (KD) was similar in both groups of patients and in healthy women (A-CRF: 0.7 +/- 0.5 x 10(-10) M; M-CRF: 1.1 +/- 0.9 x 10(-10) M; controls: 1.0 +/- 0.6 x 10(-10) M). However, VDR concentration was significantly decreased in A-CRF (0.8 +/- 0.5 fmol/10(7) cells vs. 2.3 +/- 0.9 fmol/10(7) cells in controls, p < 0.001), whereas no changes were seen in M-CRF (1.7 +/- 0.7 fmol/10(7) cells vs. 2.3 +/- 0.9 fmol/10(7) cells in controls). No correlation was seen between VDR and serum calcitriol or PTH levels, when considering both groups of patients together or separately. Conversely, a significant negative correlation was found between VDR and serum creatinine values when A-CRF and M-CRF were considered altogether (r = -0.63; p < 0.01). Treatment with two different schedules of oral calcitriol (five patients with 0.5 microgram/day for 1 month and four patients with 2 micrograms/day for 7 days) did not change VDR concentrations. We conclude that the low levels of serum 1,25(OH)2D3 of uremia are not responsible for the decrease in VDR concentration found in these patients.

Effects of radiation on endothelial function

PURPOSE

The response of endothelium to ionizing radiation was studied.

METHODS AND MATERIALS

The abdominal aorta in different experimental groups of rats was irradiated, and the response of arterial rings from the irradiated segments to norepinephrine, acetylcholine (ACh), and nitroglycerin (NTG) was studied. Nonirradiated thoracic segments in the same experimental animals were used as as a control for comparisons. Two age-matched nonirradiated control groups were also studied.

RESULTS

A poor endothelium-dependent vasodilator response was obtained with ACh in the irradiated rings and also in those not directly irradiated; the endothelium-independent vasodilator response to NTG was preserved during the first 3 days after irradiation. By 6 months, both the endothelium-dependent response and endothelium-independent response were impaired.

CONCLUSIONS

Alterations in nitric oxide synthesis and/or release by the endothelium were observed during the early phase of radiation in irradiated and nonirradiated segments. In the delayed phase of radiation, endothelium-independent muscular relaxation was also affected.

Plasma adrenomedullin levels in type 1 diabetes. Relationship with clinical parameters

OBJECTIVE

To assess the relationship between plasma adrenomedullin (AM) levels and the presence of microvascular complications in type 1 diabetic patients.

RESEARCH DESIGN AND METHODS

We measured plasma AM and cAMP levels in 103 type 1 diabetic patients (46 without complications, 24 with retinopathy only, 14 with microalbuminuria but normal kidney function, and 19 with renal insufficiency) and 41 matched healthy control subjects.

RESULTS

Patients with renal insufficiency had higher levels of AM and cAMP than all other groups. Patients with only retinopathy showed a trend to have higher levels than patients without complications. There were no differences among all other groups. There was a significant correlation between AM and cAMP in the total diabetic group (rs = 0.36, P < 0.001) but not in the control group. In multiple regression analysis, plasma AM demonstrated significant relationships with creatinine clearance (beta = -0.31, P = 0.004) and duration of the disease (beta = 0.28, P = 0.008).

CONCLUSIONS

Plasma AM and cAMP are increased in type 1 diabetic patients with renal insufficiency. Creatinine clearance (CrClc) and duration of the disease are related to plasma AM levels in these patients.

Seasonal deficiency of vitamin D in children: a potential target for osteoporosis-preventing strategies?

Peak bone mass attained after skeletal growth is a major determinant of the risk of developing osteoporosis later in life, hence the importance of nutritional factors that contribute to bone mass gain during infancy and adolescence. An adequate supply of vitamin D is essential for normal bone homeostasis. This study was undertaken to determine what the levels are of 25-hydroxyvitamin D (25(OH)D) that may be considered desirable in children and to assess if normal children maintain these levels throughout the year. Vitamin D metabolites and parathyroid hormone (PTH) serum levels were measured in 21 children in March and October, prior to and after the administration of a daily supplement of 25(OH)D (40 microg for 7 consecutive days). There were inverse correlations between basal 25(OH)D levels and supplementation-induced changes in serum 1,25(OH)2D (r = 0.57, p < 0.05) and PTH (r = 0.41, p < 0.05). When basal levels of 25(OH)D were below 20 ng/ml, the supplement induced an increase in serum 1,25(OH)2D; with basal 25(OH)D under 10-12 ng/ml, the supplement also decreased serum PTH. The lowest serum level of 25(OH)D in 43 normal children studied in summer was 13 ng/ml. Those results suggested that the lowest limit for desirable levels of 25(OH)D in children was somewhere between 12 and 20 ng/ml. However, 31% of 51 normal children studied in winter had levels below 12 ng/ml, and 80% had levels lower than 20 ng/ml. Those children are likely to have suboptimal bioavailability of vitamin D, which might hamper their achievement of an adequate peak bone mass. Since cutaneous synthesis of vitamin D is rather limited in winter, oral vitamin D supplementation should be considered.