Iron deficiency and risk factors for lower iron stores in 6–24-month-old New Zealanders

OBJECTIVES

To determine the prevalence of biochemical iron deficiency and identify factors associated with ferritin levels among 6-24-month-old urban South Island New Zealand children.

DESIGN

Cross-sectional survey conducted from May 1998 to March 1999.

SETTING

The cities of Christchurch, Dunedin and Invercargill.

SUBJECTS

A total of 323 randomly selected 6-24-month-old children participated (response rate 61%) of which 263 provided a blood sample.

METHODS

A complete blood cell count, zinc protoporphyrin, serum ferritin and C-reactive protein were measured on nonfasting venipuncture blood samples, 3-day weighed food records and general questionnaire data were collected.

RESULTS

Among children with C-reactive protein<10 mg/l (n=231), 4.3% had iron deficiency anaemia, 5.6% had iron deficiency without anaemia, and 18.6% had depleted iron stores, when a ferritin cutoff of < or =12 g/l was used. Age (negative), sex (girls>boys), ethnicity (Caucasian>non-Caucasian), weight-for-age percentiles (negative) and birth weight (positive) were associated with ferritin after adjusting for infection and socioeconomic status. When current consumption of iron fortified formula and >500 ml of cows' milk per day were included, these were associated with a 22% increase and 25% decrease in ferritin, respectively (R2=0.28).

CONCLUSIONS

The presence of suboptimal iron status (29%) among young New Zealand children is cause for concern, even though severe iron deficiency is rare, because children with marginal iron status are at risk of developing severe iron deficiency if exposed to a physiological challenge.

Lifestyle factors associated with glycaemic control and body mass index in older adults with diabetes

OBJECTIVE

To investigate the relations between lifestyle factors (diet and exercise), glycated haemoglobin (HbA(1c)) and body mass index (BMI) in older adults with diabetes.

DESIGN AND SETTING

A community hospital-based cross-sectional study of 150 noninstitutionalized, ambulatory adults (>/=65 y) with diabetes, residing within New Zealand's Kapiti region.

SUBJECTS

Patients were recruited from all general practices; two diabetes clinics; local diabetes society and through advertisements in community newspapers. A total of 211 eligible people were identified, but 60 refused to participate and one withdrew. In all, 150 people completed the study (71% participation rate).

METHODS

Nutrient intakes were calculated by a food-frequency questionnaire. Physical activity was assessed by interview using a validated questionnaire. Medical history and demographic data were obtained by interview or self-completed questionnaires; height, weight and HbA(1c) were measured. Multivariate models using bootstrapping and stepwise linear regression were used to select factors associated with HbA(1c) and BMI.

RESULTS

Each five-unit increase in energy from dietary saturated fat and five-unit increase in BMI were associated with 6% (95% confidence interval=2-10%; P=0.004) and 4% (0.3-7%; P=0.031) increases in HbA(1c), respectively. For females with moderate, compared with low overall activity, there was a 14% (7-20%; P=0.000) reduction in BMI while for males the reduction was only 5% (-1-11%; P=0.116). BMI decreased 5% (2-9%; P=0.004) with each 10-y increase in age, while a five-unit increment in energy from dietary sucrose was associated with a 6% (1-11%; P=0.025) increase in BMI.

CONCLUSIONS

Reducing dietary saturated fat and excess body weight may be useful means of improving glycaemic control in older adults with diabetes. Increasing physical activity and reducing energy from dietary sucrose may assist weight control, the former particularly in women.

Maximal response to a plasma cholesterol-lowering diet is achieved within two weeks

BACKGROUND AND AIM

Replacing saturated fat with polyunsaturated fat reduces plasma cholesterol concentrations; however, it has not been well documented how rapidly the decline occurs nor how long is required to reach the maximum cholesterol-lowering effect. The aim of the present study was to determine the time course of change in plasma cholesterol concentrations when participants adopt a lipid-lowering diet.

METHODS AND RESULTS

Participants (n = 19) were asked to follow for 19 days a diet high in saturated fat and then crossed over--without washout--for 19 days to a diet high in n-6 polyunsaturated fat. Participants were asked to maintain a total fat intake of 30-33% of total energy on both diets. Energy and nutrient intakes were assessed by self-reported food records covering 3 days. Plasma total cholesterol concentrations were measured on days 0, 1, 2, 5, 8, 12, and 19 of the n-6 polyunsaturated fat rich diet. Mean (95% CI) plasma total cholesterol concentration declined from 5.10 mmol/L (4.77, 5.46) at day 0 to 4.25 mmol/L (3.83, 4.67) on day 12 and remained unchanged at 4.23 mmol/L (3.85, 4.61) on day 19. A statistically significant decrease in plasma cholesterol concentration was achieved on day 2 of the intervention; by day 5, 59% (0.51 mmol/L) of the maximum reduction (0.87 mmol/L) had been reached.

CONCLUSIONS

Adopting a lipid lowering diet initiates an immediate decline in plasma cholesterol concentration, the full effect of which is achieved within two weeks.

Selenium and zinc status are suboptimal in a sample of older New Zealand women in a community-based study

The importance of selenium and zinc in the immune functioning of the aged is widely recognized. Seniors in New Zealand are at particularly high risk of low selenium status because of the low selenium soil environment. The zinc status of the New Zealand elderly has never been assessed. In this cross-sectional study, the biochemical selenium, zinc and lipid levels, physical functional capacity and dietary intakes of 103 randomly selected free-living New Zealand women (mean age +/- SD, 75 +/- 3 y) were assessed. Among nonusers of selenium supplements (n = 80), 80% [95% confidence interval (CI): 70; 88%] had plasma selenium levels (0.85 +/- 0.23 micromol/L) below 1.00 micromol/L [ approximately 10% below mean plasma selenium necessary for full expression of glutathione peroxidase (GPx) activity in New Zealand subjects]. Plasma selenium was strongly correlated with GPx: r = 0.56; P < 0.0001. For nonusers of zinc supplements (n = 88), serum zinc concentrations were 12.4 +/- 1.4 micromol/L, with 12% (95% CI: 6; 21%) having levels below the cut-off value (10.7 micromol/L). Estimated mean daily selenium and zinc intakes were 34 +/- 10 microg and 8.7 +/- 2.0 mg, respectively. Subjects in the highest tertile of a functional capacity index had higher biochemical zinc and selenium values than those in the lowest tertile (P < 0.05). The correlation between plasma selenium and GPx indicates that selenium intake in these women is still insufficient for full expression of GPx activity. Lower serum zinc levels also appear to be prevalent. Because a suboptimal trace element status may be more common among those with a poor physical functioning, promotion of the consumption of nutrient dense foods or supplements to improve selenium and zinc status of elderly women in New Zealand may be beneficial.

Axonal injury is accentuated in the caudal corpus callosum of head-injured patients

Amyloid precursor protein (APP) accumulation is a sensitive marker for the axonal damage that is commonly seen in the brain as the result of head injury. This form of damage is particularly associated with midline structures such as the corpus callosum, although it is not clear whether some areas are more susceptible than others. The aim of this study was to determine if there was a differential distribution of axonal injury throughout the corpus callosum after head injury in an unselected group of cases. Coronal tissue sections from eight cases were taken at different levels through the corpus callosum, including the genu, body, and splenium. The sections were immunostained with an antibody to APP, and the amount of axonal damage at the different levels was quantified using computer image analysis to build up a rostro-caudal profile for each case. The profiles revealed a significantly higher APP load in caudal parts of the corpus callosum. This supports previous nonquantitative reports in the literature and has important implications in terms of choosing where tissue should be sampled to maximize the chance of detecting axonal injury post mortem.

Effects of diaspirin crosslinked hemoglobin infusion in treadmill-exercised swine

The hemodynamic and metabolic effects of diaspirin crosslinked hemoglobin (DCLHb) were investigated using graded treadmill exercise in swine (n = 5/group). Swine received DCLHb (10% solution, 5 ml/kg) or oncotically-matched human serum albumin (HSA, 5ml/kg). Baseline metabolic and hemodynamic data were similar. In both groups exercise increased hemodynamic parameters. Exercise increased heart rate (HR) from 139 +/- 12 to 293 +/- 28 bpm with DCLHb and from 136 +/- 13 to 314 +/- 13 bpm with HSA. Exercise increased cardiac output (CO) from 5.7 +/- 0.75 to 15.6 +/- 2.01/min in the DCLHb group and from 5.3 +/- 0.48 to 15.7 +/- 0.881/min in the HSA group. However, CO returned to baseline faster with DCLHb upon stopping exercise. The DCLHb-treated group demonstrated a significantly higher oxygen extraction during exercise (12.04 +/- 0.38 vs 9.48 +/- 0.99 ml O2/100 ml blood) and a lower oxygen delivery throughout recovery (74.6 +/- 6.6 vs 102.2 +/- 7.21 O2/min), indicating enhanced oxygen delivery during exercise in the treatment group. DCLHb infusion did not impair metabolic or hemodynamic functions. These data indicate that DCLHb may increase oxygen delivery to working tissue more efficiently than HSA during treadmill exercise in swine.

Overexpression of s100beta in Down's syndrome: correlation with patient age and with beta-amyloid deposition

S100beta is an astrocyte-derived uritotrophic' cytokine which has been implicated in the pathogenesis of Alzheimer's disease. S100beta overexpression by plaque-associated astrocytes correlates with growth of abnormal (strophic') neurites in beta-amyloid plaques, one of the major neuropathological hallmarks of Alzheimer's disease. As the characteristic neuropathological changes of Alzheimer's disease are virtually universal in middle-aged Down's syndrome patients, studies of Down's syndrome patients provide a unique opportunity to investigate the pathophysiological processes underlying the development of Alzheimer-type neuropathological changes. Computerized morphometric analysis was used to quantify astrocyte activation and astrocytic expression of S100beta, and to correlate these with beta-amyloid deposition, in a clinically well-characterized cohort of Down's syndrome subjects, aged 13-65 years. There were significant positive correlations between S100beta expression and patient age, and between S100beta expression and cerebral cortical beta-amyloid deposition. Moreover, the numbers of activated (enlarged) astrocytes overexpressing S100beta showed a significant correlation with the numeric density of beta-amyloid plaques, from the youngest to the oldest ages and within age ranges where pathology is most florid, while no such relationship was found between the numbers of small, non-activated S100beta-immunoreactive cells and numerical density of beta-amyloid plaques. These correlations, together with established functions of S100beta, are consistent with the idea that S100beta overexpression promotes beta-amyloid plaque formation and progression in Down's syndrome.

A comparison of manual and semi-automated methods in the assessment of axonal injury

Diffuse axonal injury (DAI) in the central nervous system is a common cause of post-traumatic coma and may result in varying degrees of disability up to and including the vegetative state. Experimental studies in man and animals have previously relied upon semi-quantitative grading systems for determining the relationship between the extent of DAI and the clinical features of patients. Using beta-amyloid precursor protein immunocytochemistry for the detection of DAI in sections of corpus callosum from 15 cases of fatal head injury, we have developed a quantitative image analysis technique for the assessment of axonal injury. This new method is objective and reproducible and should allow better correlation with biomechanical, radiological, and clinical parameters to increase our understanding of DAI.

Is there a genetic basis for the deposition of beta-amyloid after fatal head injury?

1. Alzheimer's disease is a heterogeneous disorder that may be caused by genetic or environmental factors or by a combination of both. Abnormalities in chromosomes 1, 14, and 21 have all been implicated in the pathogenesis of the early-onset form of the disease, while the epsilon 4 allele of the apolipoprotein E gene (on chromosome 19) is now recognized as a risk factor for early- and late-onset sporadic and familial Alzheimer's disease. 2. The best-established environmental trigger for the disease is a head injury, based on epidemiological and neuropathological evidence. Approximately 30% of patients who die after a single episode of severe head injury show intracerebral deposition of beta-amyloid protein (A beta), a protein that is thought to be central to the pathogenesis of Alzheimer's disease. 3. Recent studies have revealed an over-representation of the apoE epsilon 4 allele in those head-injured patients displaying A beta pathology, thus providing the first evidence for a link between a genetic susceptibility (apoE epsilon 4) and an environmental trigger (head injury) in the development of Alzheimer-type pathology.

Nitric oxide modulation of retinal, choroidal, and anterior uveal blood flow in newborn piglets

The purpose of the present study was to investigate the role of nitric oxide (NO) in modulating the resting vascular tone of the choroidal and anterior uveal circulations and the autoregulatory gain of the retina. Blood flow (ml/min/100 gm dry weight) to tissues was determined in 23 anesthetized piglets (3-4 kg) using radiolabelled microspheres. Ocular Perfusion Pressure (OPP) was defined as mean arterial pressure minus intraocular pressure (IOP) which was manipulated hydrostatically by cannulation of the anterior eye chamber. The OPP was decreased during intravenous infusion (30 mg/kg/hr) of either the NO-synthase inhibitor L-NAME or the inactive enantiomer D-NAME. Blood flows were determined at OPP of 60, 50, 40, 30, and 20 mmHg following initial ocular blood flow measurements. Mean initial choroidal and anterior uveal blood flows with L-NAME showed a 47+/-12% and a 43+/-6% reduction (p <.001), respectively. Mean choroidal blood flows were significantly reduced (p<.01) in the L-NAME treated animals at an OPP of 60 and 50 when compared to D-NAME. Uveal blood flows were linearly correlated with OPP in the L-NAME and D-NAME treated groups. Uveal blood flow was greater following exogenous administration of L-arginine (180 mg/kg). Mean initial retinal blood flow did not differ significantly in either group. Retinal blood flow with L-NAME was reduced at OPP of 60 mmHg and below compared to D-NAME (p<.05). The degree of compensation in the autoregulatory gain of the retinal vasculature was reduced in the presence of L-NAME at an OPP of 50 mmHg and below compared to D-NAME. These data support the hypothesis that NO may be a primary mediator in maintaining resting vascular tone to the choroid and anterior uvea in vivo and that NO blockade reduces the degree of compensation in the autoregulatory gain of the retinal vasculature within a specific range of ocular perfusion pressures.

Life-long overexpression of S100beta in Down's syndrome: implications for Alzheimer pathogenesis

Chronic overexpression of the neurite growth-promoting factor S100beta has been implicated in the pathogenesis of neuritic plaques in Alzheimer's disease. Such plaques are virtually universal in middle-aged Down's syndrome, making Down's a natural model of Alzheimer's disease. We determined numbers of astrocytes overexpressing S100beta, and of neurons overexpressing beta-amyloid precursor protein (beta-APP), and assayed for neurofibrillary tangles in neocortex of 20 Down's syndrome patients (17 weeks gestation to 68 years). Compared to controls, there were twice as many S100beta-immunoreactive (S100beta+) astrocytes in Down's patients at all ages: fetal, young, and adult (p = 0.01, or better, in each age group). These were activated (i.e., enlarged), and intensely immunoreactive, even in the fetal group. There were no neurofibrillary changes in fetal or young Down's patients. The numbers of S100beta+ astrocytes in young and adult Down's patients correlated with the numbers of neurons overexpressing beta-APP (p < 0.05). Our findings are consistent with the idea that conditions--including Down's syndrome--that promote chronic overexpression of S100beta may confer increased risk for later development of Alzheimer's disease.

Glial-neuronal interactions in Alzheimer's disease: the potential role of a 'cytokine cycle' in disease progression

The role of glial inflammatory processes in Alzheimer's disease has been highlighted by recent epidemiological work establishing head trauma as an important risk factor, and the use of anti-inflammatory agents as an important ameliorating factor, in this disease. This review advances the hypothesis that chronic activation of glial inflammatory processes, arising from genetic or environmental insults to neurons and accompanied by chronic elaboration of neuroactive glia-derived cytokines and other proteins, sets in motion a cytokine cycle of cellular and molecular events with neurodegenerative consequences. In this cycle, interleukin-1 is a key initiating and coordinating agent. Interleukin-1 promotes neuronal synthesis and processing of the beta-amyloid precursor protein, thus favoring continuing deposition of beta-amyloid, and activates astrocytes and promotes astrocytic synthesis and release of a number of inflammatory and neuroactive molecules. One of these, S100beta, is a neurite growth-promoting cytokine that stresses neurons through its trophic actions and fosters neuronal cell dysfunction and death by raising intraneuronal free calcium concentrations. Neuronal injury arising from these cytokine-induced neuronal insults can activate microglia with further overexpression of interleukin-1, thus producing feedback amplification and self-propagation of this cytokine cycle. Additional feedback amplification is provided through other elements of the cycle. Chronic propagation of this cytokine cycle represents a possible mechanism for progression of neurodegenerative changes culminating in Alzheimer's disease.

Relation between delayed impairment of cerebral energy metabolism and infarction following transient focal hypoxia-ischaemia in the developing brain

Phosphorus magnetic resonance spectroscopy (31P MRS) was used to determine whether focal cerebral injury caused by unilateral carotid artery occlusion and graded hypoxia in developing rats led to a delayed impairment of cerebral energy metabolism and whether the impairment was related to the magnitude of cerebral infarction. Forty-two 14-day-old Wistar rats were subjected to right carotid artery ligation, followed by 8% oxygen for 90 min. Using a 7T MRS system. 31P brain spectra were collected during the period from before until 48 h after hypoxia-ischaemia. Twenty-eight control animals were studied similarly. In controls, the ratio of the concentration of phosphocreatine ([PCr]) to inorganic orthophosphate ([Pi]) was 1.75 (SD 0.34) and nucleotide triphosphate (NTP) to total exchangeable phosphate pool (EPP) was 0.20 (SD 0.04): both remained constant. In animals subjected to hypoxia-ischaemia, [PCr] to [Pi] and [NTP] to [EPP] were lower in the 0- to 3-h period immediately following the insult: 0.87 (0.48) and 0.13 (0.04), respectively. Values then returned to baseline level, but subsequently declined again: [PCr] to [Pi] at -0.02 h-1 (P < 0.0001). [PCr] to [Pi] attained a minimum of 1.00 (0.33) and [NTP] to [EPP] a minimum of 0.14 (0.05) at 30-40 h. Both ratios returned towards baseline between 40 and 48 h. The late declines in high-energy phosphates were not associated with a fall in pHi. There was a significant relation between the extent of the delayed impairment of energy metabolism and the magnitude of the cerebral infarction (P < 0.001). Transient focal hypoxia-ischaemia in the 14-day-old rat thus leads to a biphasic disruption of cerebral energy metabolism, with a period of recovery after the insult being followed by a secondary impairment some hours later.

Quantification of Alzheimer-type neurofibrillary lesions by automated image analysis

Neurofibrillary pathology is seen in a wide variety of disorders such as Alzheimer's disease (AD), progressive supranuclear palsy and the Parkinsonism-dementia amyotrophic lateral sclerosis complex of Guam. To assess the pathological importance of these lesions quantitative studies need to be undertaken. To date, most neuropathological studies have been based on qualitative, or at best semi-quantitative, data reporting the presence or absence of specific lesion types. To obtain such data traditionally involves laborious manual measurements, which rely heavily on the skill of the investigator and tend to have low inter- and intra-rater reliabilities. We have developed a novel analysis technique, using colour image analysis, which can accurately quantify the total amount of neurofibrillary damage present. Furthermore we have developed a set of mathematically defined morphological criteria to allow objective discrimination between the three types of neurofibrillary damage seen in the cortex immunostained with Alz-50. Use of this novel technique provides a reliable, rational means for the classification of neurofibrillary lesions.

Comparative investigation of neurofibrillary damage in the temporal lobe in Alzheimer's disease, Down's syndrome and dementia pugilistica

Neurofibrillary lesions such as neurofibrillary tangles, neurites and neuropil threads are used as neuropathological markers of Alzheimer's disease (AD). However these lesions are also seen in non-demented elderly cases as well as in several other disorders such as Down's syndrome (DS), dementia pugilistica (DP) and Parkinson's disease. Quantitative studies may therefore help in understanding the pathophysiological role of these lesions. Using a novel image analysis technique we have quantified the extent of neurofibrillary damage in AD, DS and DP. We have found that the extent of neurofibrillary change did not significantly differ between AD and DS, though there were also strong parallels between AD and DP. We conclude that both genetic (as in DS) and environmental (as in DP) risk factors for AD-type pathology provide a similar pattern of neurofibrillary degeneration to that in AD itself suggesting that similar degenerative mechanisms might be triggered in all three conditions.

A quantitative comparison of plaque types in Alzheimer's disease and senile dementia of the Lewy body type

In a previous study we reported no difference in the overall beta-amyloid protein (beta AP) load between Alzheimer's disease (AD) and senile dementia of the Lewy body type (SDLT). However, it is possible that differences in the morphology of beta AP plaque types exist, analogous to the differences in cytoskeletal pathology found in these two disorders. We have carried out a quantitative image analysis of plaque subtypes in the temporal lobe of AD (n = 8), SDLT (n = 9) and control (n = 11) cases. Measurements of beta AP load and plaque density were consistently higher in AD and SDLT than in controls. When AD and SDLT cases were compared no differences were seen in either the density or relative proportions of classic and diffuse plaques. Based on these results we suggest that the variation in the clinical course of these diseases reflects differences in the cytoskeletal pathology, whereas the final stages of profound dementia common to both disorders is associated with the deposition of beta AP.

Resuscitation from severe hemorrhage

The potential to be successfully resuscitation from severe traumatic hemorrhagic shock is not only limited by the "golden 1 hr", but also by the "brass (or platinum) 10 mins" for combat casualties and civilian trauma victims with traumatic exsanguination. One research challenge is to determine how best to prevent cardiac arrest during severe hemorrhage, before control of bleeding is possible. Another research challenge is to determine the critical limits of, and optimal treatments for, protracted hemorrhagic hypotension, in order to prevent "delayed" multiple organ failure after hemostasis and all-out resuscitation. Animal research is shifting from the use of unrealistic, pressure-controlled, hemorrhagic shock models and partially realistic, volume-controlled hemorrhagic shock models to more realistic, uncontrolled hemorrhagic shock outcome models. Animal outcome models of combined trauma and shock are needed; a challenge is to find a humane and clinically realistic long-term method for analgesia that does not interfere with cardiovascular responses. Clinical potentials in need of research are shifting from normotensive to hypotensive (limited) fluid resuscitation with plasma substitutes. Topics include optimal temperature, fluid composition, analgesia, and pharmacotherapy. Hypotensive fluid resuscitation in uncontrolled hemorrhagic shock with the addition of moderate resuscitative (28 degrees to 32 degrees C) hypothermia looks promising in the laboratory. Regarding the composition of the resuscitation fluid, despite encouraging results with new preparations of stroma-free hemoglobin and hypertonic salt solutions with colloid, searches for the optimal combination of oxygen-carrying blood substitute, colloid, and electrolyte solution for limited fluid resuscitation with the smallest volume should continue. For titrating treatment of shock, blood lactate concentrations are of questionable value although metabolic acidemia seems helpful for prognostication. Development of devices for early noninvasive monitoring of multiple parameters in the field is indicated. Molecular research applies more to protracted hypovolemic shock followed by the systemic inflammatory response syndrome or septic shock, which were not the major topics of this discussion.

Effects of soman (pinacolyl methylphosphonofluoridate) on coronary blood flow and cardiac function in swine

The effects of soman (pinacolyl methylphosphonofluoridate) on coronary blood flow, the electrocardiogram, and cardiac function were measured in alpha-chloralose-anesthetized swine. Coronary blood flow (CBF), mean arterial blood pressure (MAP), peak systolic left ventricular pressure (IVP), maximum rate of left ventricular pressure development (dP/dtmax), cardiac output, and the ECG were monitored continuously. A dose of 2X LD50 of soman (1 LD50 = 4.6 micrograms/kg) was given at 1 LD50/min in the femoral vein, which produced an increase in coronary sinus plasma acetylcholine (ACh) from a control of 0.7 +/- 0.01 nmol/ml to a maximum 314% of control at 15 min and a decrease in CBF from a control of 99 +/- 13 ml/min/100 g to a minimum 55% of control at 15 min. The increase in ACh in the coronary sinus was significantly correlated with a decrease in CBF (r = -0.87, p < 0.001). The fall in CBF was accompanied by concomitant decreases in IVP, MAP, and dP/dtmax, with S-T segment elevation and ventricular fibrillation. The increase in coronary sinus acetylcholine concentration was significantly correlated with a 10-fold fall in coronary sinus acetylcholinesterase levels from a control of 2.47 +/- 0.97 mol acetylcholine hydrolyzed/ml blood/min and was consistent with the time course for the reduced hemodynamic measurements. These studies support the hypothesis that acetylcholine increases following soman toxicity may decrease coronary blood flow, thereby initiating ischemic electrocardiographic changes and reducing cardiac function.

Altered beta-APP metabolism after head injury and its relationship to the aetiology of Alzheimer's disease

There is increasing evidence of a link between head injury and the subsequent onset of Alzheimer's disease. Deposits of amyloid beta-protein (A beta) are found not only in cases of dementia pugilistica but in some 30% of patients dying after a single episode of severe head injury. Detailed clinicopathological studies have shown that A beta deposition is most likely, but not exclusively, to occur, the older the patient at the time of injury, and if the injury is the result of a fall. Distribution studies have shown that the A beta is widely deposited in the neocortex and there is no apparent association with any of the multiple primary or secondary pathologies of traumatic brain injury. There is an increased expression of beta-APP particularly in the pre-alpha cells of the entorhinal cortex and in areas of axonal damage. Recent molecular genetic studies have shown that there is a strong association between deposits of A beta and the apolipoprotein E genotype of the individual.

Quantification of beta APP immunoreactive pre-alpha cells in the entorhinal cortex using image analysis

The neuropathological diagnosis of Alzheimer's disease requires an assessment of the quantity of pathology present. Advances in molecular biology have highlighted the role of beta-amyloid precursor protein (beta APP) in the pathogenesis of the disease. This protein is found in neurons and other cells and many neuropathological studies would benefit from a method which generates reliable data on the numbers of cells containing significant amounts of the protein. Classically, generation of such data would have involved laborious manual counting. This particular approach carries low levels of inter- and intra-rater reliability and is much dependent on the skill and experience of the operator. We have used immunocytochemistry to specifically define a single cell population, pre-alpha cells, containing beta APP, and have developed a computerized cell counting programme that can reliably quantify these cells in human post-mortem brain samples. We have obtained a high level of accuracy (> 95%) and efficiency in identifying and quantifying target cells and have demonstrated that our protocol can be used effectively by both novice and expert. This method could be easily configured to provide quantitative data for a wide range of immunocytochemically defined cell populations.

Increased numbers of beta APP-immunoreactive neurones in the entorhinal cortex after head injury

In a previous publication we hypothesized that Alzheimer's disease (AD) can be induced by the age-related increase in expression of beta-amyloid precursor protein (beta APP) in the medial temporal lobe. Head injury has also been identified as a risk factor for AD and as such, similarities should exist between the pathology found after head injury and the earliest stages of pathology in AD. In this study, we have quantified the number of beta APP-immunoreactive neurones in the medial temporal cortex (pre-alpha cells, layer II) of 13 head injured and 17 control patients. Significantly more beta APP immunoreactive neurones were observed in head injury cases (mean 18.4 per cluster) compared with controls (mean 13.4 per cluster, p < 0.05). These data provide a mechanism to explain how an environmental event such as head injury can generate the same molecular pathology (increased neuronal beta APP) as is found in the earliest stages of AD.

Effects of diaspirin crosslinked haemoglobin during coronary angioplasty in the swine

OBJECTIVE

Percutaneous transluminal coronary angioplasty produces a transient interruption of coronary blood flow during balloon inflation, giving rise to temporary regional myocardial ischaemia. Diaspirin crosslinked haemoglobin (DCLHbTM) transports oxygen in a similar way to whole blood and can be perfused through the angioplasty catheter during balloon occlusion. The aim of this study was to test the hypothesis that DCLHb may increase myocardial oxygenation and reduce myocardial ischaemia during coronary angioplasty.

METHODS

The effect of DCLHb on cardiac function was measured in diazepam sedated swine. Mean arterial blood pressure, peak systolic left intraventricular pressure, maximum rate of left ventricular pressure development (dP/dtmax), pressure-rate product, cardiac output (CO), and ECG were monitored continuously. Variables were compared during control, during 1 min balloon occlusion of the proximal left anterior descending coronary artery with a 2.5-3.5 F angioplasty catheter, during 1 min of DCLHb perfusion (40 ml.min-1) without balloon occlusion, and during 4 min balloon occlusion with DCLHb perfusion (40 ml.min-1) of the occluded region. Measurements were made during balloon occlusion plus DCLHb at 1 min (B + D1), 2 min (B + D2), and 4 min (B + D4).

RESULTS

Balloon occlusion decreased cardiac function as compared to control: arterial blood pressure -16%, intraventricular pressure -14%, dP/dtmax -34%, and pressure-rate product -40%. DCLHb alone did not significantly change haemodynamic measurements from control. At B + D4 haemodynamic variables were increased as compared to balloon occlusion alone: arterial blood pressure +32%, intraventricular pressure +29%, dP/dtmax +20%, and pressure-rate product +19%. Only intraventricular pressure and mean arterial pressure were increased compared to control. The S-T segment of the ECG was depressed by 0.109(SEM 0.019) mV during balloon occlusion without DCLHb, while only decreasing by 0.069(0.027) mV at B + D1, by 0.046(0.018) mV at B + D2, and by 0.058(0.018) mV at B + D4.

CONCLUSIONS

There is an improvement in cardiac function and a lessening of S-T segment depression during percutaneous transluminal coronary angioplasty balloon occlusion with DCLHb perfusion.

Effects of orthostatic and anti-orthostatic stress on patent and stenotic coronary arteries in swine

Head-up tilt (HUT) followed by head-down tilt (HDT) has been used to simulate the acute phase of adaptation to microgravity. This study evaluates the effects of HUT and HDT on the coronary circulation before and during coronary stenosis. Seven pigs were placed in the prone position and exposed to the following orientations for 20 min each: 1) 0 degrees horizontal (HZ); 2) +70 degrees HUT; and 3) -15 degrees HDT. The swine were then placed in the HZ position for 20 min while hemodynamics returned to baseline. The diameter of the left anterior descending (LAD) coronary artery was reduced to a point slightly less than that which produced a decrease in blood flow and the protocol was repeated. Heart rate (HR), contractility (dP/dt), mean arterial blood pressure (MABP), left ventricular pressure (LVP), coronary sinus pressure (CSP), left-ventricular end-diastolic pressure (LVEDP), coronary blood flow (CBF), coronary vascular resistance (CVR), myocardial oxygen consumption (MVO2) and coronary sinus lactate were determined after 20 min in each position. The transition from HUT to HDT elicited a significant (p < 0.05) increase in MABP, LVP, CSP, LVEDP, MVO2, and CBF and a significant decrease in CVR. During HDT, MVO2 increased 20 +/- 10% from Hz and 68 +/- 15% from HUT. There was a comparable increase in coronary artery flow. The hemodynamic responses were not significantly altered during pneumatic coronary occlusion. However, coronary sinus lactate was significantly elevated in the HDT positions. This study demonstrates a substantial increase in CBF during HUT to HDT with and without coronary stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantification of plaque types in sulci and gyri of the medial frontal lobe in patients with Alzheimer's disease

beta-Amyloid protein (beta A4) deposition was characterised in the sulci and gyri of frontal cortex in 14 cases of Alzheimer's disease. A quantitative study was made of two distinct plaque sub-types (diffuse and classic) using immunocytochemistry and image analysis using a discriminant function design. As reported previously more beta A4 was observed in sulci than gyri. Diffuse plaques were more numerous than classic plaques in sulci and gyri (P less than 0.01). Classic plaques were more abundant in the sulci (P less than 0.01). Increased beta A4 deposition in the sulci is accounted for by increased numbers of classic plaques. No correlation was observed between the numbers of diffuse and classic plaques in either region. Our data suggest that the two plaque types form discrete populations and that their evolution is governed by distinct pathophysiological parameters.

Effects of diasprin cross-linked hemoglobin (DCLHb) on cardiac function and ECG in the swine

The effects of DCLHb on cardiac function were measured in diazepam sedated (2-4 mg/min) swine. Mean arterial blood pressure (MAP), peak systolic left ventricular pressure (IVP), rate of left ventricular pressure development (dP/dt), pressure rate product (PRP), cardiac output (CO), and ECG were monitored continuously. Hemodynamic parameters were compared during control, DCLHb infusion (40 ml/min), one minute balloon occlusion (BO) of the proximal left anterior descending coronary artery (LAD) with a 2.5-3.5 F, 20 mm balloon angioplasty catheter, and four minute balloon occlusion with DCLHb (BO + DCLHb) perfusion (40 ml/min) of the LAD occluded region. Control hemodynamic values were as follows; MAP 91 +/- 6 mmHg, IVP 102 +/- 6 mmHg, dP/dt 2519 +/- 351 mmHg/min, PRP 15809 +/- 1515 mmHg.min, and CO 2.72 +/- 0.29 L/min. There was a significant reduction in cardiac function with BO as compared to control; MAP 16% decreases, IVP 14% decreases, dP/dt 34% decreases, and PRP 40% decreases. In contrast BO + DCLHb significantly increased all measurements of cardiac function, with the exception of CO as compared to control; MAP 32% increases, IVP 29% increases, dP/dt 20% increases, and PRP 19% increases. The S-T segment of the ECG was depressed by a significant 0.134 +/- 0.006 mv from control during BO. There was a significant decrease 0.093 +/- 0.045 mv in the BO + DCLHb group. These data demonstrate an increase in cardiac function and a decrease in S-T segment depression during balloon occlusion with DCLHb perfusion. Further studies are needed to define the mechanism of action of DCLHb mediated increases in cardiac function.

Adenosine and active hyperemia in soleus and gracilis muscle of cats

Exercise-induced increases in tissue adenosine level vary in muscles having different oxidative capacities. These studies were designed to further evaluate the role of this potent vasodilator as a modulator of active hyperemia in muscles having different intrinsic metabolic profiles. Soleus (slow-twitch oxidative) and gracilis (fast-twitch glycolytic) muscles of anesthetized cats were stimulated to contract isometrically in the presence of adenosine deaminase (ADA) or ADA that had been deactivated by boiling (BADA). Stimulation parameters were chosen to provide similar high and low blood flow responses in the two muscle types. ADA did not affect resting blood flow or vascular resistance. In the soleus muscle, ADA attenuated both the increase in blood flow and oxygen consumption and the decrease in vascular resistance at the high level of muscle stimulation. In addition, muscle performance decreased to 60% of its initial level in the presence of ADA, although the same initial performance level was maintained over the stimulation period during BADA infusion. Temporal studies in the soleus muscle demonstrated an ADA-induced decrease in oxygen consumption, which was the product of an attenuated blood flow, followed by reductions in muscle performance. ADA had no effect on active hyperemia in either muscle at the low stimulation level. Additionally, ADA did not attenuate active hyperemia in the gracilis when stimulated at a level that normally produced muscle fatigue. Therefore these data support a role for adenosine in mediating vasodilation in skeletal muscle composed of high-oxidative fibers at high levels of muscle performance but do not support a role for adenosine in skeletal muscle having low-oxidative fibers, even at levels of exercise which produce fatigue.

Cholinergic regulation of resting coronary blood flow in domestic swine

Cholinergic vasoconstriction in vivo and the influence of resting cholinergic activity on basal coronary tone were investigated by measuring coronary blood flow, cardiac function, and blood gases during either acetylcholine injection, muscarinic receptor blockade, or vagal ligation, in open-chest chloralose-urethan-anesthetized swine. Intracoronary injections of acetylcholine (0.5-3.0 micrograms) caused significant (P less than 0.05) dose-dependent reductions in coronary blood flow (19.0-75.5%) and conductance (14.3-78.2%). Atropine (200 micrograms) completely blocked these responses. Cholinergic mediation of basal coronary tone was initially evaluated by determining the effects of muscarinic blockade with intracoronary injection of atropine (200 micrograms). Intracoronary injection of atropine had no significant effects on coronary blood flow or conductance. Finally, to ensure that parasympathetically released acetylcholine was not overcoming the muscarinic blockade, vagal ligation was performed during pacing. Neither coronary blood flow nor conductance was significantly altered by vagal ligation. The present studies demonstrate that acetylcholine induces a muscarinic vasoconstriction of coronary arteries in the domestic swine. However, these studies do not support a role for parasympathetic mediation of basal coronary vascular tone.

Adrenergic nerve function and contractile activity of the caudal artery of the streptozotocin diabetic rat

The adrenergic nerve function and contractile responses of the densely innervated caudal artery of the 8-week streptozotocin (SZ) (65 mg/kg i.p.) diabetic rat were investigated. Segments of this artery were removed from diabetic and control rats, placed in Krebs-filled tissue baths (37 degrees C) and isometric tension recorded. Contractile responses to sympathetic nerve activation by electrical stimulation and to cumulative concentrations of norepinephrine (NE) and tyramine were recorded. In order to determine NE content, the NE was extracted from the caudal artery, isolated by adsorption chromatography, and quantified by HPLC with electrochemical detection. NE accumulation and release were also studied by quantifying the amount of tritiated NE [( 3H]NE) and its metabolites in extracts of the tissue or incubation medium. The responses of the caudal artery of SZ diabetic rats to electrical stimulation (4-16 Hz) and to tyramine (1 X 10(-5)-1 X 10(-4) M) were significantly less than those of arteries from control rats and the NE content reduced by 41%, while sensitivity to NE was unchanged. Diabetic arteries also accumulated and released more [3H]NE than did arteries from control rats. These results establish that neurovascular function of the isolated caudal artery of the 8-week SZ diabetic rat is abnormal and suggest that problems in the ability of adrenergic nerves to store and release NE may contribute to this dysfunction. Such changes may play a role in the cardiovascular disturbances associated with diabetic autonomic neuropathy.

Pressor effect of nalbuphine in hemorrhagic shock is dependent on the sympathoadrenal system

Nalbuphine, an analgesic with opiate agonist and antagonist properties, increases heart rate, mean arterial pressure (MAP), and cardiac function following a moderate hemorrhage in the rat. The interaction between opiate receptors and the sympathoadrenal system was examined in control, beta receptor-blocked, and adrenal-demedullated animals. MAP and heart rate were measured continuously in chronically instrumented conscious animals. Hemorrhage decreased MAP in the control group by 50%, and nalbuphine (1 mg/kg) returned this to prehemorrhage values within 5 min. MAP remained significantly greater in the nalbuphine-treated animals for 120 min. Heart rate fell with hemorrhage and increased above prehemorrhage values in the nalbuphine-treated animals. The pressor response to nalbuphine was abolished in both beta-blocked and adrenal-demedullated animals. Plasma catecholamines were not significantly elevated in the nalbuphine-treated as compared to control animals, which suggests that nalbuphine effects do not result from an enhancement of central mediated sympathoadrenal discharge. The opiate receptor antagonist naloxone, in a concentration that was not by itself effective in alleviating the hypotensive effects of hemorrhage, prevented the pressor response with nalbuphine. These results suggest that nalbuphine's beneficial effects in hemorrhagic shock depend on an intact sympathoadrenal system and on an interaction with opiate receptor sites, possibly in the heart.

Effect of theophylline on adenosine production in the canine myocardium

Adenosine is thought to participate in local regulation of coronary blood flow. However, competitive antagonists of adenosine fail to block myocardial active hyperemia. We examined the effect of locally administered theophylline on active hyperemia and myocardial adenosine production during intracoronary isoproterenol infusion in the dog heart. Isoproterenol decreased coronary resistance and increased myocardial adenosine production. Infusion of theophylline at a rate that attenuated the vasodilator response to exogenously administered adenosine failed to attenuate the increase in coronary blood flow produced by isoproterenol. However, theophylline plus isoproterenol produced greater increases in myocardial adenosine production than isoproterenol alone. The curves relating resistance and adenosine in the presence of theophylline fell to the right of those in the absence of theophylline. These findings suggest that the failure of theophylline to attenuate isoproterenol hyperemia in the dog heart results at least in part from an increase in adenosine concentration at the arteriole to a level beyond that blocked by this competitive antagonist and that adenosine may in fact play a role in isoproterenol-induced active hyperemia.

Tissue adenosine content in active soleus and gracilis muscles of cats

Vascularly isolated cat soleus and gracilis muscles were stimulated to contract isometrically and were then frozen in situ. Adenosine, inosine, and hypoxanthine (nucleosides), and lactate were measured in neutralized, perchloric acid extracts of muscle. During contraction, nucleoside content increased in soleus muscle but changed little in gracilis muscle. However, adenosine content did not correlate with vascular conductance or oxygen consumption in either soleus or gracilis muscle. Adenosine content did correlate with lactate content in soleus but not gracilis muscle. The activity of AMP deaminase was highest in cat gracilis muscle and lowest in dog cardiac muscle. The activity of 5'-nucleotidase was lowest in cat gracilis muscle and highest in dog cardiac muscle. Cat soleus and dog gracilis muscles had intermediate activities of both enzymes. The findings of the present study do not support a role for adenosine in mediating prolonged active hyperemia in fast-twitch gracilis muscle of cats and cast doubt on such a role in slow-twitch soleus muscle of cats. Differences in the activities of AMP deaminase and 5'-nucleotidase provide a qualitative, biochemical explanation for apparent differences in net adenosine production among muscles composed of different fiber types and between skeletal and cardiac muscle.

Changes in dog gracilis muscle adenosine during exercise and acetate infusion

We have previously reported that tissue acetate content increases in the canine gracilis muscle during exercise at natural flow. We here report the effects of exercise and infusion of acetate on adenosine content. Muscles were vascularly isolated, perfused naturally, and stimulated to contract isometrically at 0.5, 1.0, or 2.0 Hz for 10 min (n = 6 each). Exercising and contralateral control gracilis muscles were freeze clamped in situ in Wollenberger tongs at the temperature of liquid N2. Force development was maintained during contraction. Resistance decreased as a function of contraction frequency, and adenosine content increased. Tissue adenosine content correlated inversely with resistance (r = -0.57, P less than 0.001), suggesting a role for adenosine in exercise hyperemia. During intra-arterial infusion of sodium acetate into resting muscle, tissue acetate and adenosine contents increased (417-2,193 and 0.88-3.07 nmol/g, respectively), and vascular resistance decreased (17.5-6.01 mmHg X ml-1/min/100 g). Acetate and adenosine contents correlated negatively with resistance (r = -0.83, P less than 0.001, and r = -0.60, P less than 0.05, respectively) and positively with one another (r = 0.58, P less than 0.05). Relative to an infusion of sodium chloride, oxygen consumption, venous PO2, and venous ionized calcium were unaffected. The vasodilatory effect of acetate may be due, in part, to its ability to increase tissue adenosine.

The possible role of acetate in exercise hyperemia in dog skeletal muscle

The possible role of acetate in the genesis of exercise hyperemia was studied in five series of dogs. Intraarterial infusion of an isomotic solution of sodium acetate at 0.76 ml/min in the dog forelimb decreased the resistance to flow through skeletal muscle by 48%, primarily by decreasing resistance to flow through small vessels. Skin lymph flow and lymph protein concentration were unaffected. The hindlimb of the conscious dog took up acetate at rest (A-V difference, + 58.3 +/- 19.6 nmoles/ml) and put out acetate during treadmill exercise (A-V difference, -105.6 +/- 20.12 nmoles/ml); femoral venous blood acetate concentration increased by 145 nmoles/ml (control 195 nmoles/ml). In the gracilis muscle of the anesthetized dog, simulated exercise at 0.5, 1.0 or 2.0 Hz increased acetate tissue content (72, 248 and 442 nmoles/g, respectively), output (18,899, and 1,830 nmoles/100 g/min, respectively) and venous concentration (82, 49 and 39 nmoles/ml, respectively) and changes in tissue acetate content correlated with changes in vascular resistance r = 0.75, P less than 0.001. Intraarterial infusion of an isosmotic solution of sodium acetate in the quiescent gracilis muscle perfused at constant flow produced a significant (6%) decrease in resistance when arterial blood acetate was increased by a calculated 96 nmoles/ml. These studies suggest that acetate might be included among those metabolites that contribute to exercise hyperemia.U

Relationships between adenosine and coronary resistance in conscious exercising dogs

The relation between myocardial adenosine content, coronary sinus plasma concentration, and coronary vascular resistance was studied in conscious dogs during rest or treadmill exercise. Exercise at 5 mi/h for 7 min on a 20% slope had a significant threefold increase in cardiac work over that of dogs at rest. Exercise increased myocardial adenosine content from 1.35 +/- 0.54 to 8.18 +/- 0.60 nmol/g and decreased coronary vascular resistance from 1.07 +/- 0.13 to 0.69 +/- 0.08 mmHg.ml-1.min.100 g; the former correlated negatively with the latter (r = -0.74, P less than 0.01). The adenosine concentration in coronary sinus plasma increased from 108 +/- 16 to 184 +/- 18 nmol/l plasma and correlated negatively with coronary vascular resistance (r = -0.83, P less than 0.01). Myocardial adenosine content correlated positively with coronary sinus plasma adenosine concentration (r = 0.77, P less than 0.05). Low myocardial lactate content, continued lactate uptake, lack of change in the lactate-pyruvate ratio, and stable coronary sinus oxygen tension values indicated no myocardial hypoxia. These findings demonstrate the release of adenosine into coronary sinus blood and show significant correlations between myocardial adenosine content, coronary sinus adenosine concentration, and coronary vascular resistance during physiological exercise in the dog. The results support the hypothesis that adenosine regulates coronary blood flow during increased metabolic activity.

Transmural adenosine with increased cardiac work

In hearts with five different levels of myocardial performance there was an inverse correlation between myocardial adenosine content and coronary vascular resistance. Higher levels of oxygen consumption were associated with higher myocardial adenosine content and lower coronary vascular resistance. Adenosine was uniformly distributed across the myocardial wall under all conditions, except those involving increased oxygen consumption with concomitant decreased coronary input pressure, as was observed with isoproterenol infusion. Under these conditions the adenosine content of the inner wall was significantly higher than the outer wall.

Resting blood flow and oxygen consumption in soleus and gracilis muscles of cats

In contrast to previous reports, the results of the present study indicate that vascular responses of isolated soleus muscles of cats are functionally similar to those of gracilis muscles. Vascularly isolated muscles were perfused under free-flow conditions. Venous outflow was measured by a drop counter. Resting blood flows were similar in soleus (n = 16) and gracilis (n = 12) muscles, 6.6 +/- 1.2 and 3.8 +/- 0.6 ml . min-1 . 100 g-1, respectivley (P > 0.05). Resting oxygen consumption averaged 0.26 +/- 0.06 and 0.33 +/- 0.10 ml O2 . min-1 . 100 g-1 for soleus (n = 10) and gracilis muscles (n = 5), respectively (P > 0.05). In four animals, blood flow to soleus muscles measured by the microsphere technique was 2.0 +/- 0.3 ml . min-1 . 100 g-1 before and 4.6 +/- 2.1 ml . min-1 . 100 g-1 after isolation of its circulation. Before isolation, blood flow to gracilis muscle was 2.0 +/- 0.1 ml . min-1 . 100 g-1 after isolation of its circulation. Before isolation, blood flow to gracilis muscle was 2.0 +/- 0.1 ml . min-1 . 100 g-1. Both soleus and gracilis muscles exhibited active hyperemia. Autoregulation of blood flow in both muscles was weak. However, oxygen supply exceeded demand because oxygen consumption was maintained as blood flow decreased in response to reductions in perfusion pressure. There was no evidence of blood flow-limited oxygen consumption. Thus, the soleus muscles of the present study not only have low-resting blood flows and oxygen consumptions, but their responses to physiological stimuli are similar to those of gracilis muscles.

Myocardial adenosine and coronary resistance during increased cardiac performance

The relation between myocardial adenosine content and coronary vascular resistance was studied in the open-chest dog. Cardiac performance was increased by aortic constriction or by intravenous infusion of isoproterenol. Coronary blood flow was measured by the microsphere tracer technique. In control animals, adenosine content and coronary vascular resistance were 0.22 +/- 0.03 nmol/g and 1.9 +/- 0.11 mmHg . ml-1 . min . 100 g, respectively. A range of myocardial oxygen consumptions of 5.3-24 ml O2 . min-1 . 100 g-1 was elicited. This was associated with a range of coronary blood flows of 33-166 ml . min-1 . 100 g-1. There was a significant negative correlation between coronary vascular resistance and the log of the myocardial adenosine content (r = 0.77). There was no transmural gradient in adenosine content in the control and aortic-constricted groups, but there was a significant adenosine gradient in the isoproterenol-infused group in which coronary input pressure was decreased. The hearts were not ischemic, as indicated by low myocardial lactate contents and a stable coronary sinus blood pH. These results provide support for a role of adenosine in the local control of the coronary circulation during increased cardiac performance.

Coronary degeneration in sexually mature rainbow and steelhead trout, Salmo gairdneri

Correlation of coronary arteriosclerosis with sexual maturation was found in rainbow and steelhead trout. All sexually mature nonanadromous rainbow, precocial male steelhead, and adult spawning steelhead had myointimal hyperplasia but it was infrequent in immature juveniles. Lesion severity in adult rainbow and precocial steelhead approach that of spawning steelhead.