Estrogen and phytoestrogens: Effect on eNOS expression and in vitro vasodilation in cerebral arteries in ovariectomized Watanabe heritable hyperlipidemic rabbits

OBJECTIVES: To evaluate the effect of estrogen replacement therapy or soy isoflavones supplement on endothelium-dependent relaxation in vitro and gene expression of endothelial nitric oxide synthase (eNOS) in cerebral arteries in a rabbit model of human hypercholesterolemia. STUDY DESIGN: Thirty-six female ovariectomized Watanabe heritable hyperlipidemic (WHHL) rabbits were randomised to treatment with 17beta-estradiol (17beta-E(2)), SoyLife 150 or control for 16 weeks. Ring segments of basilar artery (BA) and posterior cerebral artery (PCA) were mounted in myographs for isometric tension recordings. Concentration response curves to carbamylcholine chloride, sodium nitroprusside (SNP) and l-NAME were evaluated after precontraction with potassium. Total RNA was extracted, reverse transcribed and eNOS quantitated by real-time polymerase chain reaction (real-time PCR). RESULTS: Plasma cholesterol was significantly higher at termination in the SoyLife group (P<0.0001), whereas low-density lipoprotein (LDL) cholesterol was comparable in all treatment groups. Neither treatment influenced the endothelium-dependent responses to carbamylcholine chloride or l-NAME or the endothelium-independent response to SNP in any of the arteries. Correspondingly, eNOS mRNA was similarly expressed in all treatment groups in both arteries. CONCLUSIONS: Improvement of cerebral endothelial function by estrogen or soy isoflavones in ovariectomized WHHL rabbits is not supported by the present data. The findings may be unique to the WHHL rabbit in which the hypocholesterolemic effect of estrogens mediated by upregulation of liver LDL receptors is excluded.     

Monoclonal antibodies to the cockroach nervous system

In the cockroach nervous system individual motor neurons may be identified with respect to their position in the thoracic ganglia and to the muscles they innervate. When their axons are cut they have the ability to regrow such that when regeneration is completed they have specifically reinnervated their normal target muscles. This suggests the existence of a specific intercellular recognition process between motor neurons and muscles, and that neurons innervating different muscles are biochemically distinct from one another. The goal of this study was to use hybridoma techniques to obtain monoclonal antibodies that bind to some motor neurons and not others. Mice were injected with whole nerve cord and hybridoma supernatants were screened immunohistochemically on sections of ganglion and leg muscle. The monoclonal antibodies were categorized according to four types of specificity: tissue, regional, cell-type, and neuron-subset specificities. Antibodies expressing neuron-subset specificity were obtained very rarely. The probability of their occurrence could be increased by treating the mice with immunosuppressant drugs after initial administration of immunogen or by fixing the immunogen with paraformaldehyde in a manner similar to that of the tissue sections used in the screening process. Two of the neuron-subset specific monoclonal antibodies (MAbs) are of particular interest with respect to the goals of this study. They bind to axon terminals in the muscles of some neurons and not others. They do not bind to neuronal cell bodies in the ganglion, which makes identification of the neurons difficult. However, from the known innervation pattern of the coxal depressor muscles it appears that one of these MAbs selectively binds to axon terminals from either the inhibitory motor neurons or the dorsal unpaired median cells. Other antibodies of interest bind selectively to the synapse-rich neuropile in the ganglia or to peripheral parts of the nervous system like the nerve roots.     

Determination of bone turnover by urinary excretion of 99mTc-MDP

Two metods of estimating bone turnover were investigated. The 24 h whole body retention (WBR) of intravenously injected ^99mTc methylene disphosphonate (^99mTc-MDP), a precise, accurate, and generally accepted method, was compared with a new, simple, measurement involving assessment of the 24 h urinary excretion (UE) of ^99mTc-MDP. The WBR and UE were measured in 50 normal subjects, 10 patients with thyrotoxicosis, and 10 patients with chronic renal failure. The precision was 4.8% and 2.7%, respectively, and the two methods were highly significantly correlated (r=0.99, SEE=2.9%, p<0.001). In addition, urinary ^99mTc-MDP excretions at 0 h–4 h (UE₄) and 0 h–8 h (UE₈) after injection were calculated in 49 subjects. The estimation of WBR from UE₄ or UE₈ was considerably poorer than from UE (for UE₄: r=-0.83, SEE=8.7%, and for UE₈: r=-0.90, SEE=6.8%) and the precision of UE₄ and UE₈ was 7.2% and 7.8%, respectively, and greater than those of both UE and WRR. It is concluded that the UE bone turnover measurement may become a simple, radiation dose-saving method to diagnose and monitor the treatment of metabolic bone diseases.     

REGIONAL DISTRIBUTION OF THE CARDIAC OUTPUT AND RENAL RESPONSES TO ATRIAL ATRIURETIC PEPTIDE INFUSION IN RABBITS WITH CONGESTIVE HEART FAILURE

1. A biventricular, low-output congestive cardiomyopathy was induced in 19 rabbits by administering adriamycin (16 mg/kg). The effects of alpha-rat atrial natriuretic peptide (ANP) infused at 0.1, 0.2 and 0.4 micrograms/kg per min, were then examined in terms of (i) central haemodynamics (ii) regional blood flow (iii) renal function and (iv) plasma norepinephrine and plasma renin. 2. In this dose range, ANP produced progressive and significant falls in stroke volume, cardiac output and mean arterial pressure, owing to a fall in venous return. The heart rate response to this was blunted. 3. Using radiolabelled microspheres, significant falls in the perfusion of cutaneous, gastrointestinal and musculoskeletal tissues were observed, due to reduced vascular conductances in these beds. These changes were accompanied by activation of the sympathetic nervous system as evidenced by a progressive rise in plasma norepinephrine. A significant increase in plasma renin was only observed with the highest infusion of ANP. 4. Renal blood flow was maintained in the face of a falling mean arterial pressure and cardiac output, but diuretic and natriuretic effects were absent. 5. It was concluded that the dominant influence of ANP infusion in this model of heart failure appeared to be a reduction in cardiac preload with detrimental overall haemodynamic consequences.     

Muscarinic Receptor Density in the Rat Urinary Bladder after Denervation,Hypertrophy and Urinary Diversion *

Abstract: Parasympathetic denervation of the urinary bladder results in supersensitivity to muscarinic agonists and in bladder hypertrophy. In the present study, the effects of denervation on the muscarinic receptors in the rat bladder were investigated, using a receptor binding technique with (-)³H-QNB as radioligand. The density of muscarinic receptors was increased in denervated, hypertrophied bladders but it was decreased, below that in control bladders, when the development of hypertrophy was prevented by urinary diversion. A decreased receptor density was also found in innervated bladders after urinary diversion, whereas the receptor density was unaffected by hypertrophy alone. Competition experiments with methacholine revealed no changes in the agonist binding properties of the receptors. When the present data are combined with those in previous functional studies, it seems unlikely that the muscarinic receptors in the bladder are involved in the development of supersensitivity. It is suggested that the density of muscarinic receptors in the bladder may be related to the bladder function.     

Sudden death and the forensic evaluation of neurocutaneous syndromes

On occasion the forensic evaluation of individuals who have died suddenly and unexpectedly may reveal intracranial vascular abnormalities such as capillary, venous- and arteriovenous malformations. Such vascular abnormalities may form part of a heterogeneous group of disorders called neurocutaneous syndromes and involve the skin, nervous system and other organ systems. These unusual conditions include Sturge–Weber, Osler–Weber–Rendu, Klippel–Trenaunay, Von Hippel-Lindau, Proteus and Wyburn-Mason syndromes in addition to ataxia telangiectasia. Causes and mechanisms of unexpected death include epileptic seizures, intracranial haemorrhage and thromboses. Differentiating these conditions at autopsy is important because of variable inheritance patterns and occasionally inaccurate clinical classifications. The autopsy evaluation requires review of the medical and family histories, and full external and internal examinations with photographic documentation and histologic sampling of lesions. Formal neuropathology, storage of blood and tissues for molecular studies if required, and liaison with a medical geneticist should be considered.     

Twice-daily biphasic insulin aspart 30 versus biphasic human insulin 30: a double-blind crossover study in adults with type 2 diabetes mellitus

OBJECTIVE: The purpose of this study was to compare the pharmacokinetics and pharmacodynamics of the premixed insulin analogue biphasic insulin aspart (BIAsp 30) with the equivalent premixed biphasic human insulin (BHI 30), administered twice daily, in patients with type 2 diabetes mellitus. METHODS: In this randomized, double-blind, crossover trial, 13 patients (mean age, 64 years; baseline mean glycosylated hemoglobin, 7.7%; mean body mass index, 28.1 kg/m2) received 2 weeks of treatment with BIAsp 30 and 2 weeks of BHI 30 administered immediately before dinner and breakfast. At the end of each 2-week treatment period, 24-hour serum insulin and glucose profiles were determined using specific 2-sided enzyme-linked immunosorbent assays. All pharmacodynamic and pharmacokinetic end points were analyzed using analysis of variance. RESULTS: Total daily insulin exposure was similar between treatment periods. Mean area under the total insulin concentration-time profile during the 2 hours following administration of BIAsp 30 was 17% greater than that of BHI 30 after dinner and 44% greater after breakfast; both differences were statistically significant. The maximum serum insulin aspart concentrations following BIAsp 30 were significantly higher after dinner (18%) and breakfast (35%). Peak serum insulin concentration was reached 1 hour earlier after breakfast and 45 minutes earlier after dinner in the BIAsp 30 group; differences were significant only after breakfast. The mean daily prandial glucose excursion was significantly lower for BIAsp 30 (16.2 mmol x h x L(-1)) than BHI 30 (17.9 mmol x h x L(-1)). Postprandial 4-hour glucose excursions were significantly lower with BIAsp 30 than with BHI 30 after dinner and breakfast, but were significantly greater after lunch. Mean 24-hour and nocturnal serum glucose concentrations were similar, and both insulins were associated with < or = 7 minor and no major hypoglycemic events. CONCLUSIONS: Premeal injection of BIAsp 30 in a twice-daily regimen significantly reduced overall postprandial glucose excursions. This effect may be of importance when improvement in postprandial glucose control is desired.     

What degree of work overload is likely to cause increased sickness absenteeism among nurses? Evidence from the RAFAELA patient classification system

AIM: This paper reports a study examining whether nurses' work overload is associated with increased sick leave and quantifying the loss of working days from work overload. BACKGROUND: The RAFAELA patient classification system indicates nursing care intensity in relation to an optimum and is one of the few validated monitoring instruments of patient-associated workload among nurses. However, it is not clear whether work overload is a risk factor for increased sickness absenteeism, an important occupational problem in health care. METHOD: An observational cohort study was carried out with 877 nurses, 31 wards and five Finnish hospitals. Patient-associated workload scores from the RAFAELA system were based on a 6-month monitoring period in 2004. Records of 12-month self certified (1-3 days) and medically certified (>3 days) periods of sick leave in the same year were obtained from employers' registers. FINDINGS: The mean workload was 9% (sd = 8%) above the optimum. There was a linear trend between increasing workload and increasing sick leave (P < or = 0.006). Among nurses with workload > or =30% above the optimum the rate of self certified periods of sick leave was 1.44 (95% CI 1.13-1.83) times higher than among those with an optimum workload. The corresponding rate ratio for medically certified sick leave was 1.49 (1.10-2.03). These excess rates of sickness absence resulted in 12 extra sick leave days per person-year. CONCLUSION: Measuring nurses' workload may be an important part of strategic human resource management of nurses to reduce sick leave among nurses.