Postnatal chest X-ray in children with asymptomatic congenital lung malformations.

OBJECTIVE: The clinical implications of a postnatal chest X-ray (CXR) in asymptomatic children with a prenatally diagnosed congenital lung malformation (CLM) are uncertain. We assessed the justification for the postnatal use of CXR in these children. METHODS: We included patients with CLM confirmed through chest computed tomography angiography or histopathological analysis who were asymptomatic at birth, underwent routine postnatal CXR, and participated in our standard of care prospective structured longitudinal follow-up program. Children with major associated morbidities were excluded. Primary outcomes were the positive and negative predictive values (PPV and NPV) of CXR findings for symptom development at 4 weeks and 6 months of age. Secondarily, we sought to establish whether CXR findings were associated with undergoing additional diagnostics during the initial observational hospital stay or prolonged postnatal hospital admission. RESULTS: Among 121 included patients, CXR showed no abnormalities in 35 (29%), nonspecific abnormalities in 23 (19%), and probable CLM in 63 (52%). The PPV of CXR in relation to symptom development at 4 weeks and 6 months was 0.05 and 0.25, respectively. Corresponding NPVs were 0.96 and 0.91. An association was identified between CXR findings and undergoing further diagnostics during the initial observational hospital stay (p = .047). Additional diagnostic findings did not influence clinical management. CXR findings were not associated with prolonged initial hospital stay (p = .40). CONCLUSION: The routine practice of postnatal CXR in asymptomatic patients with prenatally diagnosed CLM can be omitted, as CXR findings do not influence subsequent clinical management.

Long-term neurodevelopment in children with resected congenital lung abnormalities.

To determine whether children who underwent resection of a congenital lung abnormality (CLA) are at higher risk for neurodevelopmental impairments than peers in the general population. The study population consisted of children born between 1999-2018 who underwent resection of a symptomatic CLA. Neurocognitive development (intelligence, memory, attention, visuospatial processing, executive functioning) and motor function of this population are monitored through our structured, prospective longitudinal follow-up program at the ages of 30 months, 5, 8, and 12 years. We compared study population scores with Dutch norm values using one-sample t-tests and one-sample binominal proportion tests. Forty-seven children were analyzed. The 8-year-olds showed significant impairments in sustained attention through the Dot Cancellation Test (mean z-scores -2.4; [-4.1; -0.8], p = 0.006 and -7.1; [-12.8; -1.4], p = 0.02 for execution speed and fluctuations respectively). Visuospatial memory was impaired at 8 years, though only in 1 out of 3 assessment tools (Rey Complex Figure Test z-scores (-1.0; [-1.5; -0.5], p < 0.001). Further neurocognitive outcomes were unimpaired at all tested ages. Regarding motor function outcomes, mean z-scores of total motor functioning were unimpaired across assessed ages. However, at 8 years, significantly more children than expected had definite motor problems (18% vs 5%, 95% CI [0.052; 0.403], p = 0.022).   Conclusion: This evaluation reveals impairment in some subtests of sustained attention, visuospatial memory and motor development. However, globally, normal neurodevelopmental outcomes were found throughout childhood. We recommend testing for neurodevelopmental impairments in children who underwent surgery for CLA only if associated morbidities are present or if caregivers express doubts about their daily functioning. What is Known: • In general, surgically managed CLA cases seldom suffer from long-term surgery-related morbidity and show favorable lung function. What is New: • Long-term neurocognitive and motor function outcome appear unimpaired within surgically managed CLA cases. We recommend testing for neurodevelopmental impairments in children who underwent surgery for CLA only if associated morbidities are present or if caregivers express doubts about their daily functioning.

COllaborative Neonatal Network for the first European CPAM Trial (CONNECT): a study protocol for a randomised controlled trial.

INTRODUCTION: Consensus is lacking on the optimal management of asymptomatic congenital pulmonary airway malformation (CPAM). For future studies, the CONNECT consortium (the COllaborative Neonatal Network for the first European CPAM Trial)-an international collaboration of specialised caregivers-has established consensus on a core outcome set of outcome parameters concerning respiratory insufficiency, surgical complications, mass effect and multifocal disease. These outcome parameters have been incorporated in the CONNECT trial, a randomised controlled trial which, in order to develop evidence-based practice, aims to compare conservative and surgical management of patients with an asymptomatic CPAM. METHODS AND ANALYSIS: Children are eligible for inclusion after the CPAM diagnosis has been confirmed on postnatal chest CT scan and they remain asymptomatic. On inclusion, children are randomised to receive either conservative or surgical management. Subsequently, children in both groups are enrolled into a standardised, 5-year follow-up programme with three visits, including a repeat chest CT scan at 2.5 years and a standardised exercise tolerance test at 5 years.The primary outcome is exercise tolerance at age 5 years, measured according to the Bruce treadmill protocol. Secondary outcome measures are molecular genetic diagnostics, validated questionnaires-on parental anxiety, quality of life and healthcare consumption-, repeated imaging and pulmonary morbidity during follow-up, as well as surgical complications and histopathology. This trial aims to end the continuous debate surrounding the optimal management of asymptomatic CPAM. ETHICS AND DISSEMINATION: This study is being conducted in accordance with the Declaration of Helsinki. The Medical Ethics Review Board of Erasmus University Medical Centre Rotterdam, The Netherlands, has approved this protocol (MEC-2022-0441). Results will be disseminated through peer-reviewed scientific journals and conference presentations. TRIAL REGISTRATION NUMBER: NCT05701514.

Role of the renin-angiotensin system in prostate cancer.

Prostate cancer is highly prevalent in Western society, and its early stages can be controlled by androgen ablation therapy. However, the cancer eventually regresses to an androgen-independent state for which there is no effective treatment. The renin-angiotensin system (RAS), in particular the octapeptide angiotensin II, is now recognised to have important effects on growth factor signalling and cell growth in addition to its well known actions on blood pressure, fluid homeostasis and electrolyte balance. All components of the RAS have been recently identified in the prostate, consistent with the expression of a local RAS system in this tissue. This review focuses on the role of the RAS in the prostate, and the possibility that this pathway may be a potential therapeutic target for the treatment of prostate cancer and other prostatic diseases.

Functional angiotensin II type 2 receptors inhibit growth factor signaling in LNCaP and PC3 prostate cancer cell lines.

BACKGROUND: There is clear evidence of a tissue-based renin-angiotensin system in the prostate and studies to date suggest that AT(1)-receptor blocking drugs inhibit the growth of some prostate cancer cell lines and delay the development of prostate cancer. The present studies examine the action of Ang II in two prostate cancer cell lines and report the presence of functional AT(2)-receptors that regulate the actions of growth factors. METHODS: Immunohistochemistry was used to identify the presence of Ang II and QPCR techniques to examine AT(1)- and AT(2)-receptor mRNA expression in androgen-dependent (LNCaP) and independent (PC3) cell lines. The effects of AT(1)- and AT(2)-receptor activation upon EGF-induced DNA synthesis and ERK2 phosphorylation in these cells were also examined. RESULTS: Functional AT(2)-receptors together with Ang II were identified in both cell lines and stimulation of these receptors inhibited EGF-induced DNA synthesis and ERK2 phosphorylation. AT(1)-receptors, although present in both cell lines, were only functional in LNCaP cells where activation stimulated DNA synthesis. CONCLUSIONS: Functional AT(2)-receptors are present and have the capacity to inhibit EGF-induced prostate cancer cell growth in LNCaP and fast growing androgen-independent PC3 cell lines, whereas functional AT(1)-receptors are found only in LNCaP cells where their activation stimulates DNA synthesis.

Renal artery stenosis: a disease worth pursuing.

Consider renovascular hypertension (HT) when: Newly diagnosed hypertension presents with features that are atypical of essential hypertension; Resistant hypertension is associated with risk factors for atheroma; or Angiotensin-converting enzyme (ACE) inhibitor or angiotensin-II-receptor antagonist therapy is associated with increasing plasma creatinine levels. Atheromatous renovascular HT can often be managed medically, which includes intensive correction of cardiovascular risk factors. ACE inhibitors are probably second-line antihypertensives for patients with unilateral renal artery stenosis and two kidneys. First-line antihypertensives are diuretics, beta-blockers and calcium-channel blockers. Bilateral renal artery stenosis, or a unilateral stenosis in a patient with only one kidney, is an absolute contraindication to ACE inhibition.

Impact of a toxicology service on a metropolitan teaching hospital.

OBJECTIVE: To evaluate the impact of a toxicology service on a major metropolitan teaching hospital. METHOD: A descriptive comparative study of all patients presenting with poisoning or suspected poisoning 12 months before and after the commencement of a toxicology service. Data on length of stay in the emergency department, disposition, length of stay of admitted patients and substance(s) involved were examined. RESULTS: A total of 1,316 poisoned patients were studied. There was a statistically significant increase in self-poisonings from 612 to 704 (P = 0.002) and in the number of admissions from 113 to 192 (P < 0.05). There was no significant change in emergency department length of stay. The average length of stay for patients admitted under the care of the toxicology service decreased, especially for complicated patients. CONCLUSION: In the first 12 months of operation the toxicology service treated more patients than the 12-month period prior to commencement, achieving a decrease in average length of stay for those patients admitted to the service. The emergency department length of stay was not altered. We surmise that by decreasing average length of stay for the patients under the care of the toxicology service, the net increase in the general pool of unoccupied beds improves bed access for all emergency department patients.

Left ventricular aneurysm repair in rats: structural, functional, and molecular consequences.

OBJECTIVES: This study examined the effects of aneurysm repair in a rat model of myocardial infarction on functional indices and on the spatiotemporal distribution of cardiac contractile protein and natriuretic peptide messenger RNA. METHODS: In a rat infarct model, expanded left ventricular aneurysms were plicated 4 weeks after infarction. At 30 weeks, transverse heart sections were taken at 4 levels (apex [level 1] through base [level 4]) and assessed by in situ hybridization histochemistry to determine regional messenger RNA levels of pre-pro-atrial natriuretic peptide, cardiac alpha-actin, skeletal alpha-actin, myosin light chain-2v, and beta-myosin heavy chain. RESULTS: Rats with plicated left ventricular aneurysms had reduced left ventricular endocardial circumference (19%, P <.005), lower heart weight ratio (31%, P <.05), left ventricular end-diastolic pressures (51%, P <.05), and increased +/-dP/dt (34%-38%, P <.05). Cardiac messenger RNA levels of pre-pro-atrial natriuretic peptide were reduced in the septum (levels 2 and 3), and skeletal alpha-actin levels were reduced in the septum and left ventricular free wall of plicated rats (level 3). beta-Myosin heavy chain levels were markedly reduced in peri-infarct regions of the left ventricular free wall, septum, and right ventricle in plicated rats at level 4, whereas myosin light chain-2v levels were reduced at levels 2 and 4 in the left ventricular free wall and at level 4 in the right ventricle. CONCLUSIONS: Plication of left ventricular aneurysm after infarction in the rat significantly reduced cardiac hypertrophy, improved cardiac function, and reduced the upregulation of pre-pro-atrial natriuretic peptide and both fetal and adult contractile protein isoforms associated with cardiac hypertrophy.

Role of beta-adrenergic receptor subtypes in lipolysis.

In vitro lipolysis stimulated by low (-)-isoprenaline concentrations (< or =30 nM) in epididymal white adipocytes from Sprague-Dawley rats was inhibited at least 60-80% by the specific beta1-antagonists LK 204-545 and CGP 20712A (1 microM), suggesting that at these low (10 nM) concentrations of (-)-isoprenaline lipolysis was primarily (80%) but not solely mediated via beta1-adrenergic receptors. Low concentrations (100 nM) of (-)-noradrenaline and formoterol also confirmed a role for beta1-adrenergic receptors in mediating lipolysis at low concentrations of these agonists. At higher agonist concentrations, beta3-adrenergic receptors were fully activated and were the dominant beta-adrenergic receptor subtype mediating the maximum lipolytic response, and the maximum response was not affected by the beta1-antagonists, demonstrating that the beta3-receptor is capable of inducing maximum lipolysis on its own. Studies of lipolysis induced by the relatively beta2-selective agonist formoterol in the presence of beta1-blockade (1 microM CGP 20712A) demonstrated the inability of the beta2-selective antagonist ICI 118-551 to inhibit the residual lipolysis at concentrations of ICI 118-551 < or = 1 microM. Higher concentrations of ICI 118-551 inhibited the residual formoterol-induced lipolysis competetively, but with low affinity (approximately 500-fold lower than its beta2-adrenergic receptor pA2, 7.80 +/- 0.21), suggesting that formoterol was not acting via beta2-adrenergic receptors. These data are consistent with beta1-adrenergic receptors playing an important role in lipolysis at physiological but not pharmacological concentrations of catecholamines and that beta2-adrenergic receptors play no obvious direct role in mediating beta-adrenergic receptor agonist-induced lipolysis in vitro. Finally, racemic-SR 59230A, unlike the pure (S, S)-isomer (a beta3-selective antagonist), was found to be a nonselective antagonist at the three beta-adrenergic receptor subtypes, showing that the other enantiomers have different selectivity.

Hypotensive effect of low-fat, high-carbohydrate diet can be independent of changes in plasma insulin concentrations.

To examine the relationship between diet, blood pressure, and plasma insulin concentrations, we studied 14 healthy males who were prescribed low-fat and high-fat diets. The low-fat diet contained 25% (of energy intake) fat and 54% carbohydrate; the high-fat diet was 45% fat (predominantly saturated fat) and 36% carbohydrate. The diets were consumed over consecutive 2-week periods in random sequence, separated by a 2-week washout period. Resting supine systolic and diastolic blood pressures decreased significantly by 7 and 3 mm Hg, respectively, and plasma total cholesterol, LDL cholesterol, and HDL cholesterol concentrations all fell (by 21.6%, 25.7%, and 18.0%, respectively; all P<0.001) on the low-fat compared with the high-fat diet. Fasting glucose and the glucose area under the curve during the frequently sampled intravenous glucose tolerance test (300 mg/kg glucose load with blood sampling for 180 minutes) were significantly lower, and the glucose disappearance rate tended to be faster after the low-fat diet. In contrast, fasting insulin concentrations and the insulin response (insulin area under the curve) to glucose challenge were unchanged. Insulin sensitivity (defined as the rate of glucose disappearance per unit of insulin increase during the period 0 to 40 minutes after the glucose load) was significantly higher on the low-fat diet. These results suggest that the hypotensive effects of a low-fat, high-carbohydrate diet, although associated with an improvement in insulin sensitivity, are not mediated by changes in plasma insulin concentration.

Identification of imidazoline-receptor binding sites in cortex and medulla of the bovine adrenal gland. Colocalization with MAO-A and MAO-B.

The distribution and relative densities of imidazoline-receptor binding sites (I-RBS) in bovine adrenal gland were determined using [3H]clonidine, [3H]2-(2-benzofuranyl)-2-imidazoline ([3H]2-BFI), and [3H]rilmenidine. In light of strong evidence that I-RBS and monoamine amine oxidase enzymes are linked, the selective radioligands [3H]RO41-1049 and [3H]RO19-6327 were used to label the distribution of MAO-A and -B enzymes, respectively. [3H]Clonidine (12 nM) labeled sites in two discrete regions of the bovine adrenal gland, the zona glomerulosa (39 +/- 7 fmol/mg tissue equivalent) and inner medulla (34 +/- 1 fmol/mg tissue). Binding was nonadrenergic (i.e., not inhibited by 100 nM methoxyidazoxan) and inhibited by 60-70% by 100 nM 2-BFI, the selective I2-RBS, suggesting binding predominantly to an I2-RBS. [3H]2-BFI (5 nM), the selective I2-RBS ligand, also labeled a high density of binding sites in the zona glomerulosa (57 +/- 9 fmol/mg) and chromaffin cells in the inner medulla (53 +/- 4 fmol/mg). These sites, however, were insensitive to clonidine (100 nM). By contrast, [3H]rilmenidine (40 nM) labeled I-RBS in all regions of the adrenal gland, that is, the zonae glomerulosa (59 +/- 10 fmol/mg), fasciculata (78 +/- 10 fmol/mg) and reticularis (63 +/- 7 fmol/mg), and outer and inner medullary chromaffin cells (42 +/- 1 and 55 +/- 2 fmol/mg, respectively). Binding to sites in the zona glomerulosa was partially inhibited (16%) by 100 nM 2-BFI. These results are consistent with previous studies indicating that [3H]rilmenidine labels an I2-RBS and additional I-RBS in rat brain and kidney. The distribution of [3H]RO19-6327 (5 nM) binding resembled that of [3H]2-BFI and [3H]clonidine binding with high densities of MAO-B enzyme located in the zona glomerulosa and chromaffin cells of the inner medulla (55 +/- 7 and 76 +/- 6 fmol/mg tissue, respectively), suggesting the colocalization of MAO-B enzyme with I2-RBS. [3H]RO41-1049 (20 nM) binding to MAO-A was highest in the zona reticularis (196 +/- 7 fmol/mg tissue) compared to the zonae glomerulosa and fasciculata (90 +/- 12 and 116 +/- 14 fmol/mg tissue) and inner medulla (149 +/- 38 fmol/mg tissue). Although the existence of I-RBS in bovine adrenal chromaffin cells is well established, this is the first description of I-RBS in the adrenal cortex. Further investigations are now required to determine whether imidazolines can affect adrenal function via actions at these sites.

LK 204-545, a highly selective beta1-adrenoceptor antagonist at human beta-adrenoceptors.

LK 204-545 ((+/-)-1-(2-(3-(2-cyano-4-(2-cyclopropyl-methoxy-ethoxy)phenoxy)-2-hydro xy-propyl-amino)-ethyl)-3-(4-hydrxy-phenyl) urea), an antagonist that possesses high beta1-/beta2-selectivity in the rat, and a range of cardio-selective and non-selective beta-adrenoceptor antagonists were examined to compare their radioligand binding affinities for human beta1-, beta2- and beta3-adrenoceptors transfected into CHO cells. LK 204-545 and CGP 20712A displayed the highest beta1-/beta2- (approximately 1800 and approximately 650, respectively) and beta1-/beta3-selectivity (approximately 17000 and approximately 2200, respectively) at human beta-adrenoceptors with LK 204-545 being approximately 2.75-fold more beta1-/beta2-selective and approximately 8-fold beta1-/beta3-selective than CGP 20712A. The high potency of LK 204-545 at transfected human beta1-adrenoceptors and in functional models of rat beta1-adrenoceptors together with its high selectivity, identify it as a useful ligand for studying beta1-adrenoceptors and suggest that it may be the preferred ligand for human beta-adrenoceptor studies.

Use of computerized neuropsychological tests (CANTAB) to assess cognitive effects of antihypertensive drugs in the elderly. Cambridge Neuropsychological Test Automated Battery.

OBJECTIVE: To establish reliability and ease of use of the Cambridge Neuropsychological Test Automated Battery (CANTAB) in assessing changes in cognitive function induced by antihypertensive drugs. DESIGN AND METHODS: Standard neuropsychological testing was combined with CANTAB in a double-blind 18-week cross-over study in elderly hypertensives taking perindopril or hydrochlorothiazide/triamterene (HT). Cognitive effects were assessed by employing tests of attention, visuospatial and verbal memory, learning, reasoning, planning, problem solving, speed and coordination. Affect was assessed using two different depression-rating scales. RESULTS: Perindopril and the diuretic had no adverse effects on the various aspects of cognitive function. Mood, as assessed by the Hamilton Depression Rating Scale and the Beck Depression Inventory, was improved on Perindopril, and the error rate in the motor screening test was lower. Ambulatory blood pressure monitoring showed both drugs achieved effective 24-h control. CONCLUSIONS: The ease of use and the ability to adjust the level of testing to the requirements of individual patients, together with the reliability of longitudinal test/re-test results, indicates that CANTAB is an important addition to the methods available to quantitate adverse central nervous system drug effects. The other purpose of the study was to assess any adverse cognitive effects of perindopril against a drug HT believed to have no adverse central nervous system effects. In this context, perindopril was free of adverse effects in all the objective tests employed. In addition, there was a benefit seen in two independent assessments of depression (the Hamilton and the Beck rating scales).

Pharmacology and subcellular distribution of [3H]rilmenidine binding sites in rat brain.

We have previously reported that in rat brain membranes, [3H]rilmenidine, in addition to labelling alpha2-adrenoceptors and the I2B-subtype of imidazoline receptor binding site (I2B-RBS), may label an additional I-RBS population, distinct from previously classified I1-RBS and I2-RBS. In this study, using crude or fractionated rat brain membranes we examined the possible association of [3H]rilmenidine-labelled I-RBS with the A- and B-isoforms of monoamine oxidase (MAO) by studying the inhibition of [3H]rilmenidine binding by a number of MAO inhibitors; and comparing the maximal binding density (Bmax) and subcellular distribution of [3H]rilmenidine binding sites with that of MAO-A and MAO-B catalytic sites labelled by [3H]RO41-1049 and [3H]RO19-6327 and 12-RBS labelled by [3H]2-BFI. Inhibition of [3H]rilmenidine binding by all MAO inhibitors tested produced very shallow curves (slope 0.29-0.56). Clorgyline and moclobemide (selective MAO-A inhibitors) displayed moderate affinities (60-140 nM), while pargyline (non-selective MAO-inhibitor), RO41-1049 (selective MAO-A inhibitor) and RO19-6327 (selective MAO-B inhibitor) exhibited very low affinities (> 2 microM) for 50-75% of [3H]rilmenidine-labelled I-RBS in crude brain membranes and even lower affinity for the remaining binding. Under identical buffer conditions, the Bmax of [3H]rilmenidine-labelled I-RBS (1.45+/-0.14 pmol/mg protein) was considerably lower than those of MAO-A (13.10+/-0.15 pmol/mg) and MAO-B (10.35+/-0.50 pmol/mg) sites. These results suggest that [3H]rilmenidine does not interact directly with the active catalytic site of either MAO enzyme and could at best only associate with a subpopulation of MAO molecules. Binding studies on five fractions of rat cortex homogenates-nuclear (N), heavy (M) and light (L) mitochondrial, microsomal non-mitochondrial (P), and soluble cytosolic (S) fractions-revealed that 45% of total [3H]rilmenidine binding was present in the P fraction cf. 20 and 23% in the M and L fractions, in contrast to [3H]RO19-6327 and [3H]2-BFI which bound 11-13% in the P fraction and 36-38% and 35-44% in the M and L fractions, respectively. Binding of all ligands in the N fraction was 6-15% of total. These studies reveal that [3H]rilmenidine-labelled I-RBS, unlike the I2-RBS, are not predominantly associated with mitochondrial fractions containing the MAO enzymes (and cytochrome oxidase activity), but appear to be distributed in both the mitochondrial and plasma membrane fractions in rat cerebral cortex.

[3H]Rilmenidine-labelled imidazoline-receptor binding sites co-localize with [3H]2-(benzofuranyl)-2-imidazoline-labelled imidazoline-receptor binding sites and monoamine oxidase-B in rabbit, but not rat, kidney.

The distribution and relative densities of imidazoline-receptor binding sites (I-RBS) and monoamine oxidase (MAO)-A and -B enzyme(s) in rat and rabbit kidney were compared autoradiographically using fixed nanomolar concentrations of [3H]rilmenidine and [3H]2-(benzofuranyl)-2-imidazoline ([3H]2-BFI) to label I-RBS, and [3H]RO41-1049 and [3H]RO19-6327 to label MAO-A and -B isoenzymes, respectively. In rat kidney, high densities of I-RBS labelled by [3H]rilmenidine were observed in the cortex and outer stripe (120-280 fmol/mg tissue), in contrast to low I-RBS densities labelled by [3H]2-BFI (<4 fmol/mg). A relatively high density of [3H]RO41-1049 binding to MAO-A enzyme was present in all regions of the rat kidney (160-210 fmol/mg) compared with a low density of [3H]RO19-6327 binding to MAO-B (< 25 fmol/mg). Comparison of MAO-A and -B distributions with that of [3H]rilmenidine-labelled I-RBS strongly suggests a lack of association in rat kidney. Similarly, the extremely low densities of [3H]2-BFI-labelled I2-RBS in rat kidney contrasts with the density of MAO-A, but is consistent with the low density of MAO-B. Rabbit kidney cortex and outer stripe contained high relative densities of [3H]rilmenidine-labelled I-RBS (200-215 fmol/mg) and [3H]2-BFI-labelled I2-RBS (45-60 fmol/mg) with lower densities in the inner stripe and inner medulla (< or = 100 and 30 fmol/mg respectively). A high density of MAO-A binding was observed in the inner stripe (515 fmol/mg) with lower levels in the cortex and outer stripe (100-240 fmol/mg), while high densities of MAO-B binding were observed in the cortex and outer stripe (290-450 fmol/mg) with lower levels in the inner stripe (65 fmol/mg). The correlation between the localization of [3H]rilmenidine-labelled I-RBS and [3H]RO19-6327-labelled MAO-B in rabbit kidney (r = 0.87, P = 0.057) suggest that [3H]rilmenidine may label a binding site co-existent with MAO-B, but not MAO-A (n.s.), in this tissue, but rilmenidine did not inhibit [3H]RO41-1049 or [3H]RO19-6327 binding. The distribution of [3H]2-BFI-labelled I2-RBS overlapped the combined distributions of both MAO-A and -B isoenzymes, suggesting that [3H]2-BFI may label sites on both enzymes in the rabbit, but [3H]2-BFI binding only correlated with [3H]RO19-6327 (r = 0.84, P = 0.07), not [3H]RO41-1049 binding (n.s.). Moreover, 2-BFI only inhibited [3H]RO19-6327, not [3H]RO41-1049 binding. These data are consistent with reports that I2-RBS are located on MAO-B and allosterically influence the catalytic site. The relationship of [3H]rilmenidine- and [3H]2-BFI-labelled I-RBS and the identity of non-MAO-associated [3H]rilmenidine-labelled I-RBS requires further investigation.

Altered cardiac hormone and contractile protein messenger RNA levels following left ventricular myocardial infarction in the rat: an in situ hybridization histochemical study.

OBJECTIVES: Cardiac remodeling secondary to myocardial infarction is associated with hypertrophy of surviving myocardium and altered cardiac gene expression. The present study examined the spatiotemporal expression of cardiac contractile protein and peptide hormone mRNA following left ventricular myocardial infarction (LVMI) in the rat heart. METHODS: LVMI was produced in Wistar rats by ligation of the left anterior descending coronary artery and mRNA levels of cardiac alpha-action (sACT), ventricular myosin light chain-2(MLC-2v), beta-myosin heavy chain (beta-MHC) and pre-proatrial natriuretic peptide (ppANP) were examined at 24 h, 1 and 4 weeks) post-LVMI by in situ hybridization histochemistry with 35S-labeled oligonucleotide probes. RESULTS: Infarct size, determined at 1 week post-LVMI, was 44.5 +/- 2.7% of the combined left ventricular epi- and endocardial surface area. Myocyte fiber width, reflecting cellular hypertrophy, was increased in left ventricular, mid-septal and mid-right ventricular muscle fibers by 11-20% at 1 week post-LVMI (P < 0.05) and by 24-29% at 4 weeks (P < 0.05). At 24 h, 1 and 4 weeks post-LVMI, heart- and lung/body weight ratios were significantly elevated compared to sham-operated rats (1.3-1.8-fold, P < 0.01 and 1.6-2.9-fold, P < 0.005, respectively). PpANP mRNA levels in the left ventricle were increased 3.8- and 3.3-fold at 1 and 4 weeks (P < 0.05), with highest levels in the epicardium, papillary muscle, infundibulum and apex of the chamber. Septal and right ventricular ppANP mRNA levels were highest at 24 h post-LVMI (2.1- and 2.6-fold increase, P < 0.05) and remained elevated at 4 weeks, with maximum levels at the left endocardial surface of the septum and apex of the chambers. Atrial levels of cACT mRNA were increased 1.9-fold at 1 week post-LVMI (P < 0.05) and remained elevated at 4 weeks. Skeletal ACT mRNA, not normally expressed in the adult rat heart, was induced as early as 24 h post-LVMI in both atria, the septum and right ventricle, with discrete hybridization signal detected at the apex of the chambers and in the right ventricular free-wall, and later (1 week) in the left ventricular epicardium. MLC-2v mRNA levels were unaltered post-LVMI, except for a transitory loss of expression at 24 h in the left atria, ventricle and apical septum. In contrast, ventricular beta-MHC mRNA was markedly induced in regions containing increased ppANP mRNA, with a maximal 3.0- and 4.0-fold induction (P < 0.05) seen at 1 and 4 weeks in the left ventricle and a 3.7-fold induction at 4 weeks in the septum and right ventricle (P < 0.05). CONCLUSION: The regional increases in induced cardiac hormone and contractile protein mRNA in similar subchamber regions of the rat heart post-LVMI implies mutual activation by mechanical and/or neuroendocrine stimuli in the transcriptional response to myocardial overload.

A study of the interactive effects of oral contraceptive use and dietary fat intake on blood pressure, cardiovascular reactivity and glucose tolerance in normotensive women.

OBJECTIVE: To investigate the interactive effects of oral contraceptive pill use and dietary fat intake on cardiovascular haemodynamics and metabolic parameters in young normotensive women. DESIGN: Thirty-two women participated, of whom 16 were taking oral contraceptive pills (ethinyl-oestradiol plus levonorgestrel) and 16 were age-matched and weight-matched controls not taking such pills. Subjects consumed either a high-fat or a low-fat diet for 2 weeks in an open, randomized, crossover study lasting 6 weeks. Investigations were performed at the end of each diet during the luteal phase of the menstrual cycle. METHODS: Blood pressure was measured by 24 h ambulatory recording; cardiovascular reactivity was determined by examining blood pressure responses to systemic infusions of noradrenaline and angiotensin II and to the cold pressor test; and carbohydrate metabolism was investigated by an intravenous glucose-tolerance test. RESULTS: Plasma triglyceride levels were significantly higher in women taking oral contraceptive pills compared with non-users on both diets; however, responses of lipoprotein levels to the two diets did not differ between study groups (total and low-density lipoprotein cholesterol levels decreased by 15 and 17% in oral contraceptive pill users and by 14% each in non-users, on the low-fat compared with the high-fat diet). Fasting plasma insulin levels, the insulin-production response to administration of glucose (insulin area under the curve) and resting clinic and night-time systolic blood pressures were all significantly reduced on the low-fat diet, but only in non-users. Blood pressure responses to noradrenaline and maximal heart rate response to cold were significantly attenuated during the low-fat diet in oral contraceptive pill users. During the low-fat diet, resting systolic, 24 h systolic and diastolic blood pressures and insulin area under the curve were all significantly higher for women taking the oral contraceptive pills. Users of these pills also exhibited a greater systolic sensitivity to administration both of noradrenaline and of angiotensin II and had a higher plasma renin activity irrespective of dietary phase. CONCLUSIONS: These results confirm that oral contraceptive pills have the potential to cause adverse effects on blood pressure, cardiovascular reactivity and the insulin-production response to administration of glucose and suggest that some of the beneficial effects of a low-fat diet on these parameters may be negated in women taking oral contraceptive pills.

PIP: The interactive effects of combined oral contraceptive (OC) use and dietary fat intake on cardiovascular hemodynamics and metabolic parameters were investigated in a comparative study of 16 normotensive OC users from Australia and 16 age- and weight-matched nonuser controls. The 6-week study's crossover design allocated women to consume either a high- or low-fat diet for 2-week periods. Analyses were performed at the end of each diet during the luteal phase of the menstrual cycle. Plasma triglyceride levels were significantly higher in OC users than nonusers in both diet groups; however, responses of lipoprotein levels to the 2 diets did not differ between study groups. Total and low-density lipoprotein cholesterol levels decreased by 15% and 17%, respectively, in OC users, and by 14% each in non-OC users on the low-fat, compared to the high-fat, diet. Fasting plasma insulin levels, the insulin production response to administration of glucose, and resting clinic and night-time systolic blood pressures were all significantly reduced on the low-fat diet, but only in nonusers. In OC users, blood pressure responses to noradrenaline and maximal heart rate response to cold were significantly attenuated by the low-fat diet. During the low-fat diet, resting systolic, 24-hour systolic, and diastolic blood pressures and areas under the curve were significantly higher in the OC group. OC users also demonstrated a greater systolic sensitivity to administration of both noradrenaline and angiotensin II, and had a higher plasma renin activity, regardless of diet. Overall, these findings confirm that OCs can cause adverse effects on blood pressure, cardiovascular reactivity, and the insulin production response to glucose administration, and negate some of the beneficial effects of a low-fat diet.

Acute effects of blood pressure elevation on insulin clearance in normotensive healthy subjects.

Reduced clearance of insulin from plasma contributes to the hyperinsulinemia associated with essential hypertension (EH); however, the association between impaired insulin clearance and EH remains unexplained. Whether elevated blood pressure (BP) affects insulin clearance is unknown; therefore, we used the hyperinsulinemic euglycemic clamp to determine the effects of BP elevation on insulin clearance and sensitivity in eight healthy volunteers. Placebo infusion increased mean BP by 2.6+/-1.6 mm Hg, which was significantly less than rises produced by phenylephrine, an alpha1-adrenoceptor agonist (+11+/-1.8 mmHg, P<.05), or by angiotensin II (+13+/-1.3 mmHg, P<.01). Although beta-adrenoceptor stimulation with isoproterenol did not change mean BP (+3.6 mm Hg, P=NS), it significantly increased systolic pressure (+23+/-2.8 mm Hg versus +2.3+/-4.6 mm Hg with placebo P<.01). Insulin secretion (ie, C-peptide concentrations) was not affected by any of the treatments; however, phenylephrine significantly reduced the metabolic clearance rate of insulin (MCRinsulin) (16.6+/-1.0 mL/kg per minute with placebo versus 13.6+/-0.7 mL/kg per minute with phenylephrine, P<.01) and thereby increased plasma insulin concentrations (66+/-5.1 microU/mL with placebo versus 79+/-4.1 microU/mL with phenylephrine, P<.05). Phenylephrine also increased glucose utilization (42+/-5.8 micromol/kg per minute during placebo versus 58+/-4.8 micromol/kg per minute during phenylephrine, P<.05); however, this was proportional to the increased insulin concentrations; therefore, insulin sensitivity was unchanged. MCRinsulin and plasma insulin concentrations were not affected by angiotensin II; however, glucose utilization increased to 51+/-2.7 micromol/kg per minute (P<.01 versus placebo), indicating insulin sensitivity was increased. MCRinsulin was unaffected by isoproterenol. Thus, alpha-adrenergic stimulation but not increased BP per se is a potent regulator of insulin clearance and plasma insulin concentrations.