Induction of eotaxin expression and release from human airway smooth muscle cells by IL-1beta and TNFalpha: effects of IL-10 and corticosteroids

Eotaxin is a novel C-C chemokine with selective chemoattractant activity for eosinophils. We determined whether eotaxin could be produced by human airway smooth muscle (HASM) cells in culture and examined its regulation by interleukin-10 (IL-10) and the corticosteroid, dexamethasone. Stimulation of the cells with interleukin-1beta (IL-1beta) or tumour necrosis factor (TNFalpha) each at 10 ng ml(-1) induced the release of eotaxin protein with maximal accumulation by 24 h. Interferon-gamma (IFNgamma) alone at 10 ng ml(-1) had no effect and there was no synergy between these cytokines on the release of eotaxin. Reverse phase high performance liquid chromatographic (HPLC) analysis of supernatents from cells treated with TNFalpha (10 ng ml(-1) for 96 h showed immunoreactivity to eotaxin which eluted with the expected retention time of 34.5-35 min. Both IL-1beta and TNFalpha-induced release of eotaxin was not inhibited by dexamethasone (1 microM), however IL-10 (10 ng ml(-1)) had a significant inhibitory effect. Dexamethasone and IL-10 did not inhibit the induction of eotaxin mRNA induced by IL-1beta or TNFalpha. Thus, human airway smooth muscle cells can release eotaxin and could be an important source of chemokine production during airway inflammatory events.

Premature mortality in the United States: the roles of geographic area, socioeconomic status, household type, and availability of medical care

OBJECTIVES

This study examined premature mortality by county in the United States and assessed its association with metro/urban/rural geographic location, socioeconomic status, household type, and availability of medical care.

METHODS

Age-adjusted years of potential life lost before 75 years of age were calculated and mapped by county. Predictors of premature mortality were determined by multiple regression analysis.

RESULTS

Premature mortality was greatest in rural counties in the Southeast and Southwest. In a model predicting 55% of variation across counties, community structure factors explained more than availability of medical care. The proportions of female-headed households and Black populations were the strongest predictors, followed by variables measuring low education, American Indian population, and chronic unemployment. Greater availability of generalist physicians predicted fewer years of life lost in metropolitan counties but more in rural counties.

CONCLUSIONS

Community structure factors statistically explain much of the variation in premature mortality. The degree to which premature mortality is predicted by percentage of female-headed households is important for policy-making and delivery of medical care. The relationships described argue strongly for broadening the biomedical model.

An ombudsman for humanitarian assistance?

The early phases of a project to design and make operational an ombudsman for humanitarian assistance (HAO) are described in this paper. Beginning with a brief historical overview of the ombudsman concept, it then outlines seven key features of a potential HAO that were identified in the initial feasibility study. The main conclusion from the feasibility study was that, in principle, it is possible to design an HAO by adapting the operational frameworks of existing ombudsman schemes so as to match the needs of the humanitarian sector. Although this seems possible in theory, there still remain some major challenges requiring practical testing in a pilot phase. The most fundamental of these is how to enable the beneficiaries of aid to make their voices heard and register their views on the management of the emergency that is affecting them. Important also, are the issues of ensuring an international jurisdiction and finding sustainable ways of financing the scheme. Finally, the paper alludes to the framework of the pilot itself and how to address the main challenges ahead.

Lay beliefs about the preventability of major health conditions

Beliefs about the extent to which health problems can be prevented reflect an understanding that preventive measures can reduce adverse health events and the level of control individuals perceive that they hold over the factors that affect their health. A population survey of 1659 people conducted in 1995 in south western Sydney, Australia, found that only child drownings, tooth decay, skin cancer, and burns and scalds were considered all or mostly preventable by more than 50% of the sample. The majority of respondents did not believe that heart attacks, cervical cancer, high blood pressure, serious road injury, lung cancer and asthma deaths were all or mostly preventable. Logistic regression analysis showed that people born in an English speaking country, those with more than 10 years of education and men were significantly more likely to recognize a number of key conditions as highly preventable. The findings suggest that, in spite of the range of prevention efforts in Australia to date, these are not matched by strong beliefs within the community that prevention is possible. Communication of the opportunities and methods for prevention needs to be improved, particularly among certain population groups. The findings also indicate a need to examine social and environmental factors which are potentially reducing confidence, and subsequently and adoption of preventive behaviours.

Human lens cholesterol concentrations in patients who used lovastatin or simvastatin

OBJECTIVE

To determine whether long-term therapeutic use of the hypocholesterolemic drugs lovastatin and simvastatin significantly alters the distribution and concentration of cholesterol in the human lens. Such changes might precede observable alterations in lens structure.

METHODS

Pairs of lenses (9-13 pairs) from patients (age range, 46-81 years) who had been taking lovastatin or simvastatin before their death (estimated for the previous 2-4 years) and lenses from similarly aged control subjects were divided into outer cortex and inner cortex plus nucleus by dissolution in a detergent-containing buffer. Ten minutes of dissolution removed 17% to 19% of the lens total volume, which accounted for about 20% of the width of the equatorial cortex and 75% of the width of the sagittal cortex. This fraction plus the residual lens was homogenized, saponified, and assayed for cholesterol by gas-liquid chromatography.

RESULTS

The cortex of adult control lenses contained about 4 microg of cholesterol per cubic millimeter of volume. This concentration increased to 10 to 15 microg/mm3 in the adult nucleus and decreased to about 6 microg/mm3 in the juvenile and fetal nucleus. Treatment with neither lovastatin nor simvastatin significantly altered the concentration of cholesterol in either the cortex or nuclear fractions.

CONCLUSIONS

Variations in concentration of cholesterol along the radii of the lens reflect differences in the density or packing of fiber cell membranes. The observed distribution of cholesterol supports the recent model of the adult lens structure, which, from surface to center, is the cortex, adult nucleus,juvenile nucleus, fetal nucleus, and embryonic nucleus. Finding no significant changes in concentration of cholesterol in the cortex formed during treatment with lovastatin or simvastatin reinforces the results of clinical studies that indicate a high lenticular safety of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Nevertheless, caution is encouraged in assuming a similar ocular safety in newer drugs that inhibit cholesterol synthesis at later metabolic steps.

CLINICAL RELEVANCE

Does clinical use of hypocholesterolemic drugs alter lens cholesterol?

Smooth-muscle myosin heavy-chain SM-B isoform expression in developing and adult rat lung

The smooth-muscle cells composing the vasculature and airways of the lung display a variety of contractile protein phenotypes. To date, however, it has remained unclear how these phenotypes might contribute differentially to contractile activity. To address this issue, we made monospecific rabbit polyclonal antibodies against the difference peptide for the SM-B smooth-muscle myosin heavy chain (SMMHC) and used these to investigate the distribution of the SM-B isoform in lung. SM-B has a seven-amino acid insert in the head region that is known to result in a higher actin-activated adenosine triphosphatase activity and in vitro motility. During development, reactivity is first seen in the trachea and bronchi of saccular lung at the time of birth, when other SMMHC isoforms also are present. Immunoreactivity spreads distally through the airways as development proceeds, reaching the level of alveolar septae in the adult. Although the smaller vessels of the pulmonary vasculature react strongly with the SM-B antibody, reactivity is infrequently observed in large pulmonary vessels. Adult tracheal smooth muscle is highly and more uniformly reactive, commensurate with its relatively high maximal velocity of shortening. The differential expression of the SM-B isoform in vascular and airway smooth muscles demonstrated in this study may provide the molecular basis for functional differences between these smooth-muscle cell types and may provide one mechanism for adapting contractility in response to physiologic stresses in the lung.

Platelet activation in patients after an acute coronary syndrome: results from the TIMI-12 trial. Thrombolysis in Myocardial Infarction

This study was designed to determine the magnitude and time course of platelet activation during therapy of acute coronary syndromes with an oral platelet antagonist.

BACKGROUND

Platelet activation and aggregation are central to the pathogenesis of the acute coronary syndromes (ACS). However, few data are available on levels of platelet activation over time in patients with ACS, especially in the setting of chronic glycoprotein (GP) IIb/IIIa inhibition.

METHODS

The Thrombolysis in Myocardial Infarction (TIMI) 12 trial was a phase II, double-blind trial evaluating the effects of sibrafiban, an oral, selective antagonist of the platelet glycoprotein IIb/IIIa receptor in patients stabilized after an ACS. A subset of 90 of the 329 patients in the study had measurement of platelet activation as assessed by the expression of platelet associated P-Selectin on days 0, 7 and 28. Platelet activation was measured in blood samples that were fixed either immediately (spontaneous activation) or after 5 minute incubation with 0, 1 microM or 5 microM ADP in order to assess platelet responsiveness to very low or moderate stimulation.

RESULTS

At baseline there was a significant elevation of spontaneous platelet activation as compared to samples obtained from normal donors or from patients who did not have acute coronary syndromes (ACS patients 27.6+/-18.7%, Normal controls 8.5+/-4.4%, Patient controls 10.9+/-7.1%, p < 0.005 for both). In addition, there was a significant decrease in the levels of platelet activation with time during the 28 days of treatment with sibrafiban. Nevertheless, even on day 28, the TIMI-12 patients continued to show elevated platelet activation in comparison to the control groups (p < 0.05 for both).

CONCLUSIONS

These results suggest that platelets remain activated long after clinical stabilization post ACS. Although platelet activation decreased after one month of oral GPIIb/IIIa inhibition, levels remained higher than normal, suggesting the need for long-term antiplatelet therapy following ACS.

Prior treatment received by patients with bulimia nervosa

OBJECTIVE

This study examined the frequency with which subjects with bulimia nervosa (BN) presenting for treatment or follow-up studies had previously received either adequate pharmacologic treatment or cognitive-behavioral therapy (CBT).

METHOD

Semistructured telephone screening of individuals who called in response to advertisements about research studies was used to establish diagnoses and to clarify prior pharmacologic and psychotherapeutic treatments for BN.

RESULTS

Of 581 women responding, 353 (60.8%) had probable BN. Overall, 61.4% of these subjects had received psychotherapy (96.7%) but rarely CBT (6.9%). Over one half (63.7%) had received pharmacologic treatment, most commonly with fluoxetine (72.5%). Of those having received any medication treatment, 46.2% were judged to have received at least one adequate trial. Overall, 35.0% of those previously treated had received at least one prior course of adequate pharmacotherapy or CBT for BN.

CONCLUSION

Although efficacious treatments for BN have been established, they have not been received by most individuals presenting for further treatment.

Redox imbalance in the critically ill

The majority of deaths amongst critically ill patients requiring intensive care are attributable to sepsis and its sequelae: septic shock, the systemic inflammatory response syndrome (SIRS) and the acute respiratory distress syndrome (ARDS). Clinically, sepsis/SIRS and ARDS are characterised by disordered vascular control, manifest as systemic hypotension and peripheral vasodilation refractory to intravascular volume resuscitation and vasopressor therapy; and pulmonary hypertension. Experimental and clinical evidence demonstrates that these patients suffer from severe oxidative stress. Thus, our own and other groups have shown that the vascular pathology of sepsis/SIRS and ARDS is initiated through the uncontrolled production of reactive oxygen (ROS) and reactive nitrogen species (RNS) which modulate inflammatory cell adhesion and cause direct injury to endothelium (Fig. 1).

Risk factors for exposure to arsenic at a hazardous waste site

Communities surrounding the Rocky Mountain Arsenal (RMA), a Superfund site in Colorado, were studied in order to determine whether exposures to arsenic were greater among persons who resided there than among residents of a comparison area. A census was conducted in areas adjacent to the RMA and in a comparison area 12-15 miles distant. From a stratified random sample, 469 persons were interviewed and urine samples obtained. Arsenic was detected in urine from 43 (9.2%) of the 469 persons sampled at a detection limit of 10 ppb. Trace levels of arsenic (detectable, but non-quantifiable) were found in 184 (39.2%) of those persons sampled. Neither the frequency of detection, the arithmetic mean nor the geometric mean values for urine arsenic was found to be statistically different when persons living near the site were compared to persons from the more distant comparison area. Therefore, the data were pooled across the study areas to evaluate risk factors for exposure to arsenic in this population-based sample. Multivariate logistic regression analyses were conducted to evaluate the risk of arsenic exposure associated with variables included in the interviews while controlling for confounding. Pathways for exposure to arsenic were evaluated through analysis of residence history, occupation, hobbies, dietary habits, water supply, housing and activity patterns. Children of Hispanic origin or non-white race, children who drank less than three glasses of water daily, and children who spent more time outdoors had an increased risk of having > or = 10 ppb of arsenic in their urine. Among adults, younger persons, especially those less than 40 years of age, persons of Hispanic origin or nonwhite race, and those employed in occupations where arsenic is likely to be found had an increased risk of having > or = 10 ppb of urine arsenic. Consumption of red wine or fish during the week prior to sampling was associated with trace levels of arsenic in urine.

Microscale nutrient patches in planktonic habitats shown by chemotactic bacteria

Are nutrients available to microbial communities in micropatches long enough to influence growth and competition? And what are the sources of such patches? To answer these questions, the swimming behavior of chemotactic bacteria in seawater samples was examined. Clusters of bacteria formed in conjunction with cell lysis and excretion by protozoa. These point sources of nutrients spread into spherical patches a few millimeters in diameter and sustained swarms of bacteria for about 10 minutes. Within that time, a large proportion of the nutrients was encountered by bacteria, chemotactic and nonchemotactic alike. Chemotaxis is advantageous for bacteria using patches over a certain size.

Pacific Rim report: Australia

Some of the major barriers to telemedicine adoption relate to the immaturity of the industry, the limited telecommunications infrastructure, the lack of appropriate dialogue between vendors and buyers about solutions required, and the lack of industry partnerships. Remuneration is only one barrier. There are, of course, other substantial organizational, financial and attitudinal barriers. However, there are many promising aspects of the telemedicine industry in Australia that could provide the foundation for future innovation and expansion.

Structure of the human cytomegalovirus B capsid by electron cryomicroscopy and image reconstruction

The three-dimensional structure of B capsids of the beta-herpesvirus human cytomegalovirus (HCMV) was investigated at a resolution of 3.5 nm from electron cryomicrographs by image processing and compared with the structure obtained for the alpha-herpesvirus herpes simplex virus type 1 (HSV-1). The main architectural features of the HSV-1 and HCMV capsids are similar: the T = 16 icosahedral lattice consists of 162 capsomers, composed of two distinct morphological units, 12 pentamers and 150 hexamers, with triplex structures linking adjacent capsomers at positions of local threefold symmetry. The main differences in the HSV-1 and HCMV capsids are found in the diameter of the capsids (125 and 130 nm, respectively); the hexamer spacing and relative tilt (center-to-center hexon spacing at outer, edge, 17.9 and 15.8 nm, respectively); the morphology of the tips of the hexons (similar in length but 33% thinner in HCMV); and the average diameter of the scaffold (44 and 76 nm, respectively). By analogy with HSV-1, the mass on the HCMV hexon tip is attributed to the smallest capsid protein (HCMV gene UL48/49). The differences in capsid structure are discussed in relation to the ability of the HCMV structure to package a genome some 60% larger than that of HSV-1.

Interactive effects of cocaine and gender on thymocytes: a study of in vivo repeated cocaine exposure

This study used a mouse model including both sexes to assess the impact of repeat cocaine exposure on the differentiation and function of T cell in thymus. Cocaine hydrochloride in 0.9% saline, 5 mg or 40 mg/kg, was administrated by i.p. injection to C57BL/6 mice for 10 days. Thymocytes were obtained 24 h after the 10th injection. Repeat in vivo cocaine exposure inhibited the proliferation of T lymphocytes in response to Con-A and Con-A plus anti-CD28. The proliferation induced by IL-2 in the Con-A stimulated T blasts was attenuated in cocaine treated mice. These effects were seen at a lower cocaine dose in female mice. The total number of thymocytes was reduced. Although the percentage of mature thymocytes (CD4+ CD8- and CD4- CD8+ cells) was not altered, the absolute cell numbers were attenuated. Both percentage and absolute cell number of immature thymocytes (CD4+ CD8+) decreased and the pre-mature (CD4- CD8-) cells increased. CD28 and CD25 expression were attenuated in Con-A stimulated thymocytes of mice treated with cocaine at 40 mg/kg. Interleukin 2 production was not significantly altered, however, gamma-IFN production was decreased by cocaine exposure at 40 mg/kg. In conclusion, cocaine exerts inhibitory effects on the function of mature thymocytes, and on the differentiation of thymocytes. A gender difference in response to cocaine was noted in that female mice were more sensitive to lower dose of cocaine exposure.

Effect of pravastatin on cardiovascular events in older patients with myocardial infarction and cholesterol levels in the average range. Results of the Cholesterol and Recurrent Events (CARE) trial

BACKGROUND

A majority of all myocardial infarctions occur in patients who are 65 years of age or older and have average cholesterol levels, but little information is available on whether cholesterol lowering in such patients reduces the rate of recurrent cardiovascular disease.

OBJECTIVE

To determine whether pravastatin reduces the rate of recurrent cardiovascular events in older patients.

DESIGN

Subset analysis of a randomized, controlled trial.

SETTING

80 hospitals and affiliates in the United States and Canada.

PATIENTS

1283 patients aged 65 to 75 years who had had myocardial infarction and had a plasma total cholesterol level less than 6.2 mmol/L (240 mg/dL) and a low-density lipoprotein cholesterol level of 3.0 to 4.5 mmol/L (115 to 174 mg/dL).

INTERVENTION

Pravastatin, 40 mg/d, or placebo.

MEASUREMENTS

Five-year event rates of major coronary events (coronary death, nonfatal myocardial infarction, angioplasty, or bypass surgery) and stroke.

RESULTS

Major coronary events occurred in 28.1% of placebo recipients and 19.7% of pravastatin recipients (difference, 9.0 percentage points [95% CI, 4 to 13 percentage points]; relative risk reduction, 32%; P < 0.001). Coronary death occurred in 10.3% of the placebo group and in 5.8% of the pravastatin group (difference, 4.6 percentage points [CI, 1.9 to 6.5 percentage points]; relative risk reduction, 45%; P = 0.004). Stroke incidence was 7.3% in the placebo group and 4.5% in the pravastatin group (absolute reduction, 2.9 percentage points [CI, 0.3 to 4.5 percentage points]; relative reduction, 40%; P = 0.03). The numbers of older patients needed to treat for 5 years were 11 (CI, 8 to 24) to prevent a major coronary event and 22 (CI, 15 to 53) to prevent a coronary death. For every 1000 older patients treated, 225 cardiovascular hospitalizations would be prevented compared with 121 hospitalizations in 1000 younger patients.

CONCLUSIONS

In older patients with myocardial infarction and cholesterol levels in the average range, pravastatin is associated with a clinically important reduction in risk for major coronary events and stroke. Given the high cardiovascular event rate in older patients, the potential for absolute benefit in this age group is substantial.

Failure of clonidine to stimulate feeding in healthy humans

The alpha2-adrenergic system is involved in the regulation of food intake in animals but its effects on feeding in humans are unknown. We hypothesized that clonidine administration would stimulate food intake in healthy human subjects. Ten men and 4 women, all physically and psychiatrically healthy, received clonidine 3 microg/kg or placebo, orally, in blinded, balanced, randomized order. Consumption of a liquid test meal was measured; also, serum growth hormone levels were used as a secondary measure of clonidine effects. Visual analog scale ratings of hunger, satiety, and sedation were obtained before, during, and after the test meal. A subset of five subjects also received 1.5 microg/kg clonidine, in addition to the two trials described above. Test meal consumption was greater following placebo than following clonidine. Sedation ratings were substantially higher at all time points after clonidine and correlated with meal consumption (correlation coefficient r = -0.584; p = 0.028). Hunger and satiety ratings did not differ. The 1.5 microg/kg dose did not provide different effects on feeding from that seen with placebo. Contrary to our hypothesis, clonidine did not stimulate food intake in humans. Sedation associated with clonidine administration may have suppressed any effects on feeding.

A double-blind placebo-controlled evaluation of the human electrophysiologic effects of zatebradine, a sinus node inhibitor

The purpose of this study was to evaluate the electrophysiologic effects of zatebradine, a sinus node inhibitor, in human subjects. Patients without structural heart disease were randomized to receive intravenous zatebradine (23 patients) or placebo (12 patients). Electrophysiologic measures were obtained at baseline and repeated at 40 and 70 min after drug administration. In the placebo group, there were no significant changes in any parameter over time. After zatebradine, sinus node function changed significantly at 40 min, with no further change at 70 min; sinus cycle length was prolonged by 16 and 17% (p < 0.001), and corrected sinus node recovery time was prolonged by 30 and 22% (p = 0.008). Similarly, atrioventricular node function changed significantly at 40 min, with no further change at 70 min; atrio-His interval was prolonged by 15 and 15% (p = 0.02), atrioventricular node effective refractory period was prolonged by 12 and 11% (p = 0.01), and Wenckebach cycle length was prolonged by 15 and 11% (p = 0.002). Atrial refractoriness, His-Purkinje conduction, ventricular refractoriness, and action-potential duration were not affected by zatebradine. Zatebradine, a sinus node inhibitor, alters the conduction and refractory properties of the human atrioventricular node, in addition to the expected effect on sinus node function.

Histological studies of the dorsal nasal, angularis oculi, and facial veins of sheep (Ovis aries)

Selective brain cooling (SBC) requires vasoactivity in the superficial veins of the face of the animal. This vasoactivity is possible because of an adequate amount of smooth muscle in the tunica media of each of these superficial vessels, enabling it to act as a "muscle sphincter". In this study, the angularis oculi, dorsal nasal, distal, and proximal parts of the facial veins in sheep were examined histologically to describe an anatomical basis for SBC. Measurements of the tunica media thickness, the lumen diameter, and the ratio of these measurements showed that the relative tunica media thicknesses in the angularis oculi vein and the dorsal nasal vein are statistically smaller (P < 0.001) than in the distal or the proximal parts of the facial vein. In the angularis oculi, dorsal nasal, and distal part of the facial vein, the tunicae mediae were composed of five to seven circularly arranged smooth muscle layers, suggesting their ability to vasoconstrict. The proximal part of the facial vein possesses both circularly and longitudinally arranged smooth muscle layers. The circular smooth muscle layers suggest a vasoconstrictory function, whereas the longitudinal smooth muscle layers suggest a vasoconstrictory function in this part of the facial vein. Both the dorsal nasal and the proximal part of the facial vein, but not the angularis oculi or the distal part of the facial vein, possess endothelial valves near their confluences with other veins. It was concluded from this study that the angularis oculi and the distal part of the facial vein vasoconstrict, whereas the proximal part of the facial vein vasodilates, enabling the necessary changes in blood flow in SBC.

Molecular mechanisms that underlie structural and functional changes at the postsynaptic membrane during synaptic plasticity

The synaptic plasticity that is addressed in this review follows neurodegeneration in the brain and thus has both structural as well as functional components. The model of neurodegeneration that has been selected is the kainic acid lesioned hippocampus. Degeneration of the CA3 pyramidal cells results in a loss of the Schaffer collateral afferents innervating the CA1 pyramidal cells. This is followed by a period of structural plasticity where new synapses are formed. These are associated with changes in the numbers and shapes of spines as well as changes in the morphometry of the dendrites. It is suggested that this synaptogenesis is responsible for an increase in the ratio of NMDA to AMPA receptors mediating excitatory synaptic transmission at these synapses. Changes in the temporal and spatial properties of these synapses resulted in an altered balance between LTP and LTD. These properties together with a reduction in the inhibitory drive increased the excitability of the surviving CA1 pyramidal cells which in turn triggered epileptiform bursting activity. In this review we discuss the insights that may be gained from studies of the underlying molecular machinery. Developments in one of the collections of the cogs in this machinery has been summarized through recent studies characterizing the roles of neural recognition molecules in synaptic plasticity in the adult nervous systems of vertebrates and invertebrates. Such investigations of neural cell adhesion molecules, cadherins and amyloid precursor protein have shown the involvement of these molecules on the morphogenetic level of synaptic changes, on the one hand, and signal transduction effects, on the other. Further complex cogs are found in the forms of the low-density lipoprotein receptor (LDL-R) family of genes and their ligands play pivotal roles in the brain development and in regulating the growth and remodelling of neurones. Evidence is discussed for their role in the maintenance of cognitive function as well as Alzheimer's. The molecular mechanisms responsible for the clustering and maintenance of transmitter receptors at postsynaptic sites are the final cogs in the machinery that we have reviewed. Postsynaptic densities (PSD) from excitatory synapses have yielded many cytoskeletal proteins including actin, spectrin, tubulin, microtubule-associated proteins and calcium/calmodulin-dependent protein kinase II. Isolated PSDs have also been shown to be enriched in AMPA, kainate and NMDA receptors. However, recently, a new family of proteins, the MAGUKs (for membrane-associated guanylate kinase) has emerged. The role of these proteins in clustering different NMDA receptor subunits is discussed. The MAGUK proteins are also thought to play a role in synaptic plasticity mediated by nitric oxide (NO). Both NMDA and non-NMDA receptors are highly clustered at excitatory postsynaptic sites in cortical and hippocampal neurones but have revealed differences in their choice of molecular components. Both GABAA and glycine (Gly) receptors mediate synaptic inhibition in the brain and spinal cord. Whilst little is known about how GABAA receptors are localized in the postsynaptic membrane, considerable progress has been made towards the elucidation of the molecular mechanisms underlying the formation of Gly receptors. It has been shown that the peripheral membrane protein gephyrin plays a pivotal role in the formation of Gly receptor clusters most likely by anchoring the receptor to the subsynaptic cytoskeleton. Evidence for the distribution as well as function of gephyrin and Gly receptors is discussed. Postsynaptic membrane specializations are complex molecular machinery subserving a multitude of functions in the proper communication between neurones. Despite the fact that only a few key players have been identified it will be a fascinating to watch the story as to how they contribute to structural and functional plasticity unfold.

The effect of sinus node depression on heart rate variability in humans using zatebradine, a selective bradycardic agent

Zatebradine is a bradycardic agent with a selective effect on the pacemaker current in the sinus node. The effect of such drugs on heart rate variability is not known. Thirty-six patients without structural heart disease were randomly assigned to receive 10 mg of zatebradine i.v. (n = 24) or isotonic saline (n = 12). Heart rate variability (HRV) was recorded as power in the very low frequency (VLF, 0.003-0.040 Hz), low frequency (LF, 0.040-0.150 Hz), and high frequency (HF, 0.150-0.400 Hz) spectral bands as well as total power (TP, 0.003-0.400 Hz) during 5-min ECG acquisitions at baseline, 30, and 60 min following the start of the infusion. No change in heart rate variability was detected in the control group. Zatebradine significantly reduced heart rate variability at 60 min in all frequency bands: VLF (-12+/-4%, p<0.001), LF (-19+/-4%, p<0.001), and HF (-26+/-5%, p<0.001). The reduction in HRV following zatebradine is due to depression of sinus node response to all external stimuli and underscores the need for documentation of normal sinus node function in HRV research.

Purification, G protein activation, and partial amino acid sequence of a novel phospholipase C from squid photoreceptors

Invertebrate visual signal transduction is initiated by rhodopsin activation of a guanine nucleotide binding protein, Gq, which stimulates phospholipase C (PLC) activity. We have previously purified a 140-kDa PLC enzyme from squid photoreceptors that is regulated by squid Gq. In these studies, an additional PLC enzyme was purified from the cytosol of squid photoreceptors and identified as a 70-kDa protein by SDS-polyacrylamide gel electrophoresis. Hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) by PLC-70 was optimal at pH 5 in the presence of 100 microM Ca2+ with a specific activity of 10.3 micromol min-1 mg-1. A polyclonal antibody raised against purified PLC-70 did not recognize purified PLC-140, and proteolytic digestion of the two purified enzymes with trypsin or Staphylococcus aureaus V8 protease showed distinct patterns of peptide fragments, indicating that PLC-70 is not a fragment of PLC-140. The partial amino acid sequence of the protein showed homology with PLC21 and norpA isozymes cloned from Drosophila, and mammalian PLC beta isozymes. Reconstitution of purified GTPgammaS-bound soluble squid Gq with PLC-70 resulted in significant enhancement of PIP2 hydrolysis over a range of Ca2+ concentrations and shifted the maximum activation by calcium to 1 microM. These results suggest that cephalopod phototransduction is mediated by Gq activation of more than one cytosolic PLC enzyme.

Influence of socioeconomic and cultural factors on racial differences in late-stage presentation of breast cancer

CONTEXT

Breast cancer mortality is higher among African American women than among white women in the United States, but the reasons for the racial difference are not known.

OBJECTIVE

To evaluate the influence of socioeconomic and cultural factors on the racial difference in breast cancer stage at diagnosis.

DESIGN

Case-control study of patients diagnosed as having breast cancer at the University Medical Center of Eastern Carolina from 1985 through 1992.

SETTING

The major health care facility for 2 rural counties in eastern North Carolina.

SUBJECTS

Five hundred forty of 743 patients with newly diagnosed breast cancer and 414 control women from the community matched by age, race, and area of residence.

MAIN OUTCOME MEASURES

Breast cancer stage at diagnosis.

RESULTS

Of the 540 patients, 94 (17.4%) presented with TNM stage III or IV disease. The following demographic and socioeconomic factors were significant predictors of advanced stage: being African American (odds ratio [OR], 3.0; 95% confidence interval [CI], 1.9-4.7); having low income (OR, 3.7; 95% CI, 2.1-6.5); never having been married (OR, 2.9; 95% CI, 1.4-5.9); having no private health insurance (OR, 2.5; 95% CI, 1.6-4.0); delaying seeing a physician because of money (OR, 1.6; 95% CI, 1.1-2.5); or lacking transportation (OR, 2.0; 95% CI, 1.2-3.6). Univariate analysis also revealed a large number of cultural beliefs to be significant predictors. Examples include the following beliefs: air causes a cancer to spread (OR, 2.8; 95% CI, 1.8-4.3); the devil can cause a person to get cancer (OR, 2.1; 95% CI, 1.2-3.5); women who have breast surgery are no longer attractive to men (OR, 1.9; 95% CI, 1.1-3.5); and chiropractic is an effective treatment for breast cancer (OR, 2.4; 95% CI, 1.4-4.4). When the demographic and socioeconomic variables were included in a multivariate logistic regression model, the OR for late stage among African Americans decreased to 1.8 (95% CI, 1.1 -3.2) compared with 3.0 (95% CI, 1.9-4.7) for race alone. However, when the belief measures were included with the demographic and socioeconomic variables, the OR for late stage among African Americans decreased further to 1.2 (95% CI, 0.6-2.5).

CONCLUSIONS

Socioeconomic factors alone were not sufficient to explain the dramatic effect of race on breast cancer stage; however, socioeconomic variables in conjunction with cultural beliefs and attitudes could largely account for the observed effect.