Secondary electrospray ionization-mass spectrometry: breath study on a control group.

A series of fatty acids among other compounds have recently been detected in breath in real time by secondary electrospray ionization mass spectrometry (SESI-MS) (Martínez-Lozano P and Fernández de la Mora J 2008 Anal. Chem. 80 8210). Our main aim in this work was to (1) quantify their abundance in breath calibrating the system with standard vapors and (2) extend the study to a control group for several days, both under fasting conditions and after sucrose intake. For the quantitative study, we fed our system with controlled amounts (∼140-1440 ppt) of fatty acid vapors (i.e. propanoic, butanoic, pentanoic and hexanoic acids). As a result, we found sensitivities ranging between 1 and 2.2 cps/ppt. Estimated concentrations of these particular acids in the breath of a fasting subject were in the order of 100 ppt. These values were in reasonable agreement with those expected from reported typical plasma concentrations and Henry constants. A second set of experiments on three fasting individuals before and after ingesting 15 g of sucrose showed that the concentration of propionic and butanoic acids increased rapidly in breath for two subjects. This response was attributed to bacterial activity in mouth and pharynx. In contrast, a third subject showed no response to the administration of sucrose. In addition, we performed a survey among six fasting subjects comparing nasal and mouth exhalations during 11 days, 4 months apart. The signal intensity was comparable for mouth and nose breath. This observation, in conjunction with the quantitative study, suggests that these compounds are mostly systemic when measured under fasting conditions. We finally used the NIST MS search algorithm to evaluate the possibility of recognizing a breathing subject based on his/her breath signature. The global recognition score was 63% (41 out of 65), while the probability by chance alone was 6 × 10(-17). This indicates that (i) there are statistically recognizable differences in individual breath patterns and (ii) the breath pattern for a given subject is relatively stable in time. This is consistent with previous NMR-based studies indicating the existence of stable individual metabolic phenotypes.

Age- and gender-related oxidative status determined in healthy subjects by means of OXY-SCORE, a potential new comprehensive index.

Oxidative stress has been related to various diseases, gender and ageing, and has been measured by various markers. The authors developed a procedure to compute a global oxidative stress index (OXY-SCORE), reflecting both oxidative and antioxidant markers in healthy subjects. Its performance was tested in relation to age and gender and in coronary artery disease (CAD) patients. Eighty-two healthy subjects and 20 CAD patients were enrolled. Plasma free and total malondialdehyde (F- and T-MDA), glutathione disulphide/reduced form ratio (GSSG/GSH) and urine isoprostanes (iPF2alpha-III) levels were combined as oxidative damage markers (damage score). GSH, alpha- and gamma-tocopherol (TH) levels, and individual antioxidant capacity were combined as antioxidant defence indexes (protection score). The OXY-SCORE was computed by subtracting the protection score from the damage score. Among single parameters, T-MDA and iPF2alpha-III significantly correlated with age; only GSH and both tocopherols correlated with male gender in healthy subjects. The OXY-SCORE was positively associated with age (p=0.004) and male gender (p=0.03). As expected, the OXY-SCORE was higher in CAD with a very significant p-value (<0.0001), after adjusting for age, gender and smoking. Combining different markers can potentially provide a powerful index in the evaluation of oxidative stress related to age, gender and CAD status.

Characterisation of the rat SK4/IK1 K(+) channel.

BACKGROUND AND AIMS: The Ca(2+)-activated K(+) channel rSK4 is the rat homologue of the human SK4/IK1 (KCNN4) channel. In colonic mucosa rSK4 plays a key role during acetylcholin-induced secretion. This study was aimed to characterize the properties of the rat SK4 channel. METHODS: Electrophysiological measurements were performed on rSK4 expressing Xenopus laevis oocytes and rat colonic crypts. Intracellular Ca(2+) activity was assessed by Oregon Green fluorescence measurements. RESULTS: The 10 pS rSK4 expressed in oocytes was Ca(2+)-sensitive and inhibited by calmodulin antagonists. 1-ethyl-2-benzimidazolinone (1-EBIO), a known activator of SK4/IK1 channels, also activated rSK4. 1-EBIO affected the current neither at saturating Ca(2+) activities nor under Ca(2+)-free conditions, but increased the Ca(2+) sensitivity of rSK4. rSK4 was strongly activated by cytosolic ATP. However, PKA itself, PKA inhibitors and mutation of the PKA phosphorylation site (S332A) did not affect channel activity. The PKC activator 1,2-dioctanoyl-sn-glycerol and the PKC inhibitor bisindolylmaleimide also failed to influence rSK4. CONCLUSION: The Ca(2+)-sensitive rSK4 is activated by 1-EBIO probably via facilitation of the Ca(2+)-calmodulin-rSK4 interaction. The strong ATP-activation of rSK4 is likely to be caused by phosphorylation via a yet unknown kinase and might involve additional subunits.

Abnormalities of coagulation in hypertensive patients with reduced creatinine clearance.

PURPOSE: The prothrombotic state that occurs in uremic patients may increase their cardiovascular risk. We studied hypertensive patients with mild-to-moderate impairment of renal function to determine if they had evidence of abnormalities in the coagulation system. SUBJECTS AND METHODS: Renal function was assessed in 382 patients with essential hypertension, in whom 24-hour creatinine clearance, urinary protein excretion, and microalbuminuria were measured. We evaluated the function of the coagulation system by measurement of platelet counts, prothrombin time, partial thromboplastin time, and plasma antithrombin III, fibrinogen, D-dimer, and prothrombin fragment 1 + 2 levels. RESULTS: Impaired renal function, defined as a creatinine clearance of 30 to 89 mL per minute per 1.73 m(2) of body surface area, was found in 168 (44%) of the patients. Age, blood pressure, duration of hypertension, and plasma levels of fibrinogen, D-dimer, prothrombin fragment 1 + 2, and lipoprotein(a) were significantly greater in these patients than in those with normal renal function; these differences persisted after adjustment for potential confounders. Creatinine clearance was significantly and inversely correlated with levels of plasma fibrinogen (Spearman's rho = -0.26, P <0.001), D-dimer (rho = -0.33, P <0.001), and prothrombin fragment 1 + 2 (rho = -0.20, P <0.001). Levels of plasma fibrinogen (P = 0.009) and D-dimer (P = 0.003) were correlated with renal function independent of age, blood pressure, duration of hypertension, triglyceride level, urinary protein excretion, and erythrocyte sedimentation rate. Lipoprotein(a) levels were correlated with fibrinogen (rho = 0.16, P = 0.003) and D-dimer (rho = 0.26, P <0.001) levels. CONCLUSIONS: Increased plasma levels of fibrinogen, D-dimer, and prothrombin fragment 1 + 2 are present in hypertensive patients with mildly decreased creatinine clearance, suggesting that the coagulation system is activated in these patients.

Increased fibrinogen levels and hemostatic abnormalities in patients with arteriolar nephrosclerosis: association with cardiovascular events.

Increased plasma fibrinogen levels and hemostatic abnormalities suggestive of a prothrombotic state are present in patients with end-stage renal failure and could contribute to increased cardiovascular morbidity in these patients. We investigated the relationship between abnormalities of the hemostatic system and the degree of renal failure and whether these abnormalities are associated with increased prevalence of cardiovascular events in patients with arteriolar nephrosclerosis. In 425 patients recruited at a hypertension clinic we assessed the renal function by creatinine clearance, urinary protein excretion, and microalbuminuria, the prevalence of atherosclerotic disease, and measured prothrombin time, activated partial thromboplastin time. fibrinogen, prothrombin fragment 1+2 (F1+2), D-dimer, and antithrombin. Early impairment of renal function (creatinine clearance, 30 to 89 ml/min per 1.73 m2 of body surface area) caused by arteriolar nephrosclerosis was found in 172 patients. Patients with early renal failure were significantly older and had significantly greater values of blood pressure, plasma fibrinogen, F1+2, and D-dimer than patients with normal renal function. Elevated D-dimer and fibrinogen levels were independently associated with the presence of decreased creatinine clearance. Log fibrinogen, log F1+2, and log D-dimer were inversely correlated with creatinine clearance. The prevalence of coronary artery, cerebrovascular, and peripheral vascular disease was significantly greater in patients with mild renal failure than in those with normal renal function. Elevated levels of fibrinogen and D-dimer were associated with the presence of atherosclerotic disease independent of renal function and other risk factors. In conclusion, changes in hemostatic parameters occur early in the course of renal failure in patients with arteriolar nephrosclerosis, suggesting a prothrombotic state that may contribute to the risk for atherosclerotic disease at all levels of renal function.

Lipoprotein (a), haemostatic variables and cardiovascular damage in hypertensive patients.

OBJECTIVE: Lipoproteins and coagulation factors are independent predictors of atherothrombotic events in the general population and their interaction may contribute to the development of cardiovascular damage. This study was designed to assess relationships between lipoproteins, haemostatic variables, and atherosclerotic complications in hypertensive patients. METHODS: In 389 untreated essential hypertensive patients recruited at a hypertension clinic, we measured plasma lipids, apolipoproteins, lipoprotein (a), apolipoprotein (a) isoforms, fibrinogen, and parameters that directly reflect the coagulation activation. Hypertensive patients were compared to 92 normotensive controls. RESULTS: Univariate analysis showed log lipoprotein (a) concentrations to be significantly correlated with age (P< 0.02), apolipoprotein B (P< 0.02), plasma fibrinogen (P< 0.001), and fibrin D-dimer (P< 0.001) levels, but not with body mass index, blood pressure, dietary fat intake, cholesterol, triglycerides, apolipoprotein Al, prothrombin fragment 1 + 2, and antithrombin III. The relationship of lipoprotein (a) with fibrinogen and D-dimer was present in both sexes, whereas the relationship of lipoprotein (a) with age and apolipoprotein B was found only in males. Multiple regression analysis showed that both fibrinogen and D-dimer were independently related with lipoprotein (a). Elevated fibrinogen, D-dimer, and lipoprotein (a) levels were significantly and independently associated with clinical evidence of atherosclerotic disease. To investigate whether the relationships of lipoprotein (a) with coagulation parameters are genetically determined, we analysed apolipoprotein (a) phenotypes in a subset of 188 hypertensive patients. While lipoprotein (a) levels were inversely correlated with apolipoprotein (a) isoform protein size, both fibrinogen and D-dimer concentrations were comparable in patients with apolipoprotein (a) isoforms of different size. CONCLUSIONS: This study demonstrates a relationship between lipoprotein (a) and clotting variables in hypertensive patients that may contribute to atherosclerotic damage in these patients. There is no evidence of a genetic background for this relationship.

Relationship of fibrinogen levels and hemostatic abnormalities with organ damage in hypertension.

Elevated plasma levels of fibrinogen and activated coagulation pathways are risk factors of cardiovascular disease in the general population. In a cross-sectional study of a case series, we investigated the relationship between fibrinogen and hemostatic markers with target-organ damage (TOD) in patients with arterial hypertension. Prothrombin time, partial thromboplastin time, fibrinogen, fibrin D-dimer, prothrombin fragment 1+2 (F1+2), and antithrombin III were measured in 352 untreated patients with mild to moderate essential hypertension and 92 normotensive controls. Staging of TOD was assessed according to W.H.O. guidelines by clinical evaluation and laboratory tests including measurements of creatinine clearance, proteinuria, ophthalmoscopy, electrocardiography, echocardiography, and ultrasound examination of major arteries. F1+2 concentrations were significantly greater in hypertensive patients than normotensive controls and were positively correlated with blood pressure. Age, blood pressure levels, duration of hypertension, smoking, HDL-cholesterol, triglycerides, and plasma fibrinogen, fibrin D-dimer, and F1+2 levels were significantly related to the presence and severity of TOD in univariate analysis. Plasma fibrinogen and D-dimer levels were related to organ damage independent of age, blood pressure, duration of hypertension, and smoking status. Separate analysis indicated significant association of fibrinogen and D-dimer levels with cardiac, cerebrovascular, peripheral vascular, and renal damage. In conclusion, elevated plasma levels of fibrinogen and a prothrombotic state are associated with the presence and severity of TOD in patients with essential hypertension and may contribute to the development of atherosclerotic disease in these patients.

Lipoprotein(a) and apolipoprotein(a) isoforms and proteinuria in patients with moderate renal failure.

BACKGROUND: Atherosclerotic diseases are a major cause of death in patients with renal failure. Increased serum concentrations of lipoprotein(a) [Lp(a)] have been established as a genetically controlled risk factor for these diseases and have been demonstrated in patients with moderate renal failure, suggesting that this lipoprotein contributes to the increased cardiovascular risk seen in these patients. Variable alleles at the apolipoprotein(a) [apo(a)] gene locus are the main determinants of the serum Lp(a) level in the general population. The purpose of this study was to investigate apo(a) isoforms in patients with moderate renal failure and mild proteinuria (less than 1.0 g/day). METHODS: In 250 consecutive subjects recruited at a hypertension clinic, we assessed the renal function by 24-hour creatinine clearance, proteinuria, and microalbuminuria, as well as the prevalence of atherosclerotic disease, and we also measured apo(a) isoforms, serum albumin, and Lp(a) concentrations. RESULTS: Moderate impairment of renal function (creatinine clearance, 30 to 89 ml/min per 1.73 m2 of body surface area) was found in 97 patients. Lp(a) levels were significantly greater in patients with moderate renal failure (21.7+/-23.9 mg/dl) as compared with patients with normal renal function (15.6+/-16.4 mg/dl, P<0.001), and an inverse correlation was observed between log Lp(a) and creatinine clearance (r = -0.181, P <0.01). However, no difference was found in the frequency of low molecular weight apo(a) isoforms between patients with normal (25.5%) and impaired (27.8%) renal function. Only patients with the smallest size apo(a) isoforms exhibited significantly elevated levels of Lp(a), whereas the large-size isoforms had similar concentrations in patients with normal and impaired renal function. No significant relationship was found between serum Lp(a) and proteinuria. Clinical and laboratory evidence of one or more events attributed to atherosclerosis was found in 9.8% of patients with normal renal function and 25.8% of patients with moderate renal failure (P<0.001). CONCLUSIONS: These results indicate that renal failure per se or other genes beside the apo(a) gene locus are responsible for the elevation of serum Lp(a) levels in patients with moderate impairment of renal function. The elevation of Lp(a) levels occurs independently of the level of proteinuria and may contribute to the risk for atherosclerotic disease in these patients.

Increased serum lipoprotein(a) levels in patients with early renal failure.

BACKGROUND: Elevated serum lipoprotein(a) levels have been found in patients with end-stage renal disease and in patients undergoing dialysis, suggesting that this lipoprotein contributes to the increased cardiovascular risk seen in these patients. It is not known whether lipoprotein(a) levels are elevated in the early phases of renal disease. OBJECTIVE: To evaluate levels of lipoprotein(a) and other lipids and the prevalence of atherosclerotic disease in patients with early renal failure. DESIGN: Cross-sectional study. SETTING: Hypertension clinic of a university medical center. PATIENTS: 257 patients with normal renal function and 160 patients with early impairment of renal function (creatinine clearance, 30 to 89 mL/min per 1.73 m2 of body surface area). MEASUREMENTS: Renal function was assessed by 24-hour creatinine clearance, proteinuria, and microalbuminuria. Cardiovascular disease status was also assessed. Serum lipoprotein(a), lipids, apolipoproteins, and apolipoprotein(a) isoforms were measured. RESULTS: Age, blood pressure, and serum lipoprotein(a) levels were greater in patients with early renal failure than in those with normal renal function and were independently associated with the presence of decreased creatinine clearance. Serum lipoprotein(a) and creatinine clearance were inversely correlated. The prevalence of coronary artery, cerebrovascular, and peripheral vascular disease was greater in patients with early renal failure than in those with normal renal function. The frequency distribution of apolipoprotein(a) isoforms was similar in patients with normal and those with impaired renal function. CONCLUSIONS: Serum lipoprotein(a) levels are elevated in patients with early impairment of renal function and are associated with greater prevalence of cardiovascular disease. An inverse correlation between serum lipoprotein(a) level and creatinine clearance and a frequency distribution of apolipoprotein(a) isoforms similar to that of normal patients point to decreased renal catabolism as a probable mechanism of lipoprotein(a) elevation in patients with early renal failure.

Glucose metabolism and insulin receptor binding and mRNA levels in tissues of Dahl hypertensive rats.

Increased insulinemic response to an oral glucose load has been demonstrated in Dahl salt-sensitive hypertensive rats. To determine whether this abnormality is mediated at the level of the insulin receptor, we compared insulin receptor binding and mRNA levels in tissues of Dahl salt-sensitive rats (DS) and in their normotensive controls, Dahl salt-resistant rats (DR). To evaluate possible influences of dietary sodium intake, rats were fed either low (0.07% NaCl) or high salt (7.5% NaCl) chow until the DS became hypertensive, and then were killed by decapitation. Fasting plasma glucose and plasma insulin levels did not differ between DR and DS rats and were not affected by salt intake. In response to an oral glucose load, plasma glucose had a similar increase in DR and DS rats, but the increase in plasma insulin was significantly greater in DS rats. Scatchard analysis of binding was obtained from in situ autoradiographic studies performed in frozen skeletal muscle and kidney sections, and insulin receptor mRNA levels were measured by slot-blot hybridization. Number and affinity of insulin receptors were comparable in skeletal muscle and kidney of DR and DS rats and, in both groups, binding parameters were not affected by dietary sodium chloride. Hepatic and renal insulin receptor mRNA levels were also comparable in DR and DS rats fed either low or high salt chow. Thus, increased plasma insulin response to oral glucose load is associated with normal insulin receptor binding and gene expression in peripheral tissues in rats with Dahl hypertension. A postreceptor defect is likely responsible for the decreased sensitivity to insulin in this model of genetic hypertension.

Effects of angiotensin II on insulin receptor binding and mRNA levels in normal and diabetic rats.

Both the density and level of mRNA encoding insulin receptors in the kidney are inversely related to the dietary sodium content, suggesting a feedback mechanism that limits the insulin-induced sodium retention when extracellular fluid volume is expanded. Because angiotensin II affects tissue sensitivity to insulin in humans, we investigated whether angiotensin II affects insulin receptor binding and mRNA levels in the kidney, liver, and renal arteries of normal rats and rats with streptozotocin-induced diabetes mellitus. Non-diabetic and diabetic rats were infused for 7 days with either vehicle or angiotensin II at a rate of 200 ng. kg-1. min-1. In a separate experiment, normal rats were treated with an angiotensin converting enzyme inhibitor (captopril, 100 mg/dl in the drinking water) or vehicle for 7 days. Regional analysis of insulin receptor binding in the kidney and renal arteries was performed by an in situ technique using computerized microdensitometry and emulsion autoradiography. Insulin receptor mRNA levels were determined in renal and hepatic tissue by Northern blot hybridization and normalized with 28S rRNA. No differences in blood pressure were observed among diabetic and non-diabetic rats infused with either vehicle or angiotensin II, whereas captopril-treated rats had significantly lower blood pressure levels than their respective controls. Angiotensin II significantly decreased plasma renin concentration in both non-diabetic and diabetic rats. Insulin receptor number was significantly greater in the renal cortex of diabetic rats than in non-diabetics, whereas no significant differences were found in the outer medulla, inner medulla, or renal arteries. Angiotensin II infusion did not affect either the number or affinity of insulin receptors in any of the renal regions studied. Insulin receptor mRNA levels were significantly greater in the kidney and liver of diabetic rats than in non-diabetics and were not affected by angiotensin II infusion. Similar to angiotensin II infusion, captopril treatment did not affect either renal insulin receptor binding or mRNA levels. Thus, diabetic rats have increased insulin receptor binding and mRNA levels in comparison to non-diabetic rats. Angiotensin II infusion and captopril treatment do not affect insulin receptor binding and mRNA levels in the kidney, arguing against a role for this peptide in the modulation of renal sensitivity to insulin.

Association of serum lipoprotein(a) levels and apolipoprotein(a) size polymorphism with target-organ damage in arterial hypertension.

OBJECTIVE: To investigate the association between lipoprotein(a) [Lp(a)] and other plasma lipids and apolipoproteins and target-organ damage (TOD) in patients with arterial hypertension. DESIGN: Cross-sectional study of a case series. SETTING: University medical center. PARTICIPANTS: Lipoprotein(a) and apolipoproteins were analyzed in 277 untreated patients with mild to moderate essential hypertension and in 102 healthy controls. Apolipoprotein(a) [apo(a)] phenotypes were additionally analyzed in an independent sample set of 106 hypertensive and 105 control subjects. MAIN OUTCOME MEASURES: Staging of TOD obtained according to World Health Organization guidelines by clinical evaluation, and laboratory tests including measurments of creatinine clearance, proteinuria, ophthalmoscopy, electrocardiography, echocardiography, and ultrasound examination of major arteries; levels of lipids, apolipoproteins, Lp(a), fibrinogen, and apo(a) phenotypes. RESULTS: Blood pressure, duration of hypertension, and levels of total cholesterol, low-density lipoprotein cholesterol, apolipoprotein B, Lp(a), and fibrinogen were significantly related to the presence and severity of TOD in univariate analysis. Stepwise multivariate analysis showed Lp(a) levels (P<.001) to be the best discriminator of the presence of TOD, followed by systolic blood pressure (P<.001), duration of hypertension (P=.01), and low-density lipoprotein cholesterol (P=.04). The Lp(a) levels were related to TOD independent of the level of blood pressure. We confirmed this association between Lp(a) concentrations and severity of TOD in a second independent sample set and observed a significantly higher frequency of low-molecular-weight apo(a) isoforms with increasing severity of TOD (P=.02). CONCLUSIONS: Lipoprotein(a) and apo(a) phenotype are sensitive indicators of the severity of TOD in patients with essential hypertension, and their evaluation might permit identification of hypertensive subjects liable to the development of organ damage. The higher frequency of low-molecular-weight apo(a) isoforms in patients with TOD demonstrates a genetically determined risk for the development of TOD in hypertensive patients.

Hypertension and abnormalities of carbohydrate metabolism possible role of the sympathetic nervous system.

To investigate the relationships between the sympathetic nervous system (SNS) and parameters of glucose metabolism in arterial hypertension, daily urinary excretion of catecholamines and plasma glucose, insulin, and C-peptide response to an oral glucose load (OGL) have been evaluated in 77 untreated patients with mild-to-moderate essential hypertension and in 31 normotensive controls. Urinary excretion of norepinephrine (UNE) was positively correlated with body mass index and with plasma glucose levels both at fast and after OGL. No correlations were found between urinary excretion of catecholamines and plasma insulin and C-peptide levels both at fast and in response to OGL. Because the frequency distribution of UNE was bimodal, hypertensive subjects were separated into two subgroups using an arbitrary cutoff, and the parameters of glucose metabolism were compared. Subjects with UNE > 205 microg/day had greater levels of fasting glucose and greater glycemic response to OGL than subjects with UNE < 205 microg/day, whereas no significant differences between the groups were found in fasting and stimulated plasma insulin and C-peptide. Thus, activation of SNS is related to glucose tolerance but not hyperinsulinemia and insulin hypersecretion in essential hypertension. Plasma glucose levels, independent of insulin, may contribute to the relationship between SNS activity and blood pressure in essential hypertension.

Abnormalities of insulin receptors in spontaneously hypertensive rats.

Insulin resistance is present in some strains of rats with genetic hypertension. To determine whether this abnormality is present at the level of the insulin receptor, we compared insulin sensitivity, insulin receptor binding, and mRNA levels in tissues of 10-week-old spontaneously hypertensive rats (SHR) and their normotensive Wistar-Kyoto (WKY) controls. Because we have previously demonstrated an inverse relationship between dietary sodium intake and renal insulin receptor density and mRNA levels in normal Sprague-Dawley rats, the two rat strains in the current experiment were fed either low salt (0.07% NaCl) or high salt (7.5% NaCl) chow until the SHR became hypertensive. Fasting plasma glucose and plasma insulin levels did not differ between SHR and WKY and were not affected by salt intake. When the rats were maintained on the low salt diet, the rate of glucose infusion required to main euglycemia during a hyperinsulinemic clamp was significantly lower in SHR than WKY. High salt diet decreased the rate of glucose utilization during the hyperinsulinemic clamp in WKY but not SHR. During the low salt diet, insulin infusion decreased sodium excretion in both WKY and SHR. When the rats were maintained on the high salt diet, the antinatriuretic response to insulin was blunted in WKY but not SHR. Both the density and mRNA levels of insulin receptor were comparable in the kidney of WKY and SHR, but only WKY had the previously demonstrated decrease in receptor number and mRNA levels when fed the high salt chow. Hepatic insulin receptor mRNA levels were significantly lower in SHR than WKY fed the low salt diet. High salt diet decreased significantly insulin receptor mRNA levels in the liver of WKY but not of SHR. Thus, SHR appear to have lost the feedback mechanism that normally limits insulin-induced sodium retention when extracellular volume is expanded. A decreased expression of insulin receptor in the liver of SHR provides a possible explanation for the insulin resistance and decreased insulin clearance present in this strain.

Benign familial macrocytosis.

We have identified a 52-year-old woman and her 27-year-old daughter with macrocytosis, normal haemoglobin and mean corpuscular haemoglobin concentration. Macrocytosis could be demonstrated from the age of 40 and 25 respectively. All blood tests were normal including vitamin B12 and folic acid. Bone marrow investigation showed rare macroblasts without other abnormalities. Endoscopy of the upper gastrointestinal tract and ultrasonography of the abdomen were normal. Thus, persistent macrocytosis was present without evidence of diseases that might account for it. In these subjects, macrocytosis is likely to be related to the presence of a genetic defect.

Abnormalities of autonomic nervous system in hyperadrenergic orthostatic hypotension: description of a case.

Hyperadrenergic orthostatic hypotension was diagnosed in a 27-year-old man because of recurrent episodes of hypotension associated with high plasma noradrenaline levels. In this patient, laboratory tests were performed to evaluate autonomic nervous system function. Decreased response to Valsalva maneuver and carotid sinus massage indicated decreased baroreflex and vagal responsiveness, respectively. Cardiovascular response to the handgrip was reduced in comparison to controls. Passive leg raise showed normal reduction of plasma norepinephrine, indicating normal responsiveness of cardiopulmonary receptors. 'Non-dipper' profile in the ambulatory blood pressure monitoring provided further evidence for an impaired autonomic control of cardiovascular function in this patient. This report suggests the presence of autonomic dysfunction in hyperadrenergic orthostatic hypotension.