Increased glutathione and glutathione peroxidase in lungs of individuals with chronic beryllium disease

Reactive oxygen species (ROS) are mediators of chronic tissue damage and fibrosis. Endogenous antioxidants may increase in response to oxidants and reduce tissue injury. We investigated the antioxidant response of the lungs to the chronic release of ROS, as occurs in the immune-specific granulomatous inflammation of chronic beryllium disease (CBD), and compared it with that in healthy controls and individuals exposed to cigarette smoke. The antioxidants superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glutathione (GSH) were quantitated in lung epithelial lining fluid (ELF) and serum from control subjects (n = 10), cigarette smokers (n = 8), and individuals with CBD (n = 9). GPx activity and extracellular GPx (eGPx) protein were increased in the ELF of subjects with CBD in comparison with that of control subjects and smokers (eGPx in ELF: controls, 1.3 +/- 0.2 microgram/ml, smokers, 1.9 +/- 0.3 microgram/ml, CBD, 3.8 +/- 0.8 microgram/ml; p = 0.002; GPx U/ml ELF, controls 1.4 +/- 0.3, smokers 1.8 +/- 0.4, CBD, 4.5 +/- 1, p = 0.02). Smokers' ELF had higher levels of GSH than that of controls, but CBD patients' ELF contained much more GSH than that of either controls or smokers (p < 0.001). Increases in GSH were correlated with eGPx, indicating similar inducing mechanisms for these antioxidants. Thus, coordinate augmentation of the glutathione antioxidant system occurs in granulomatous lung inflammation.

High rate of human T lymphotropic virus type IIa infection in HIV type 1-infected intravenous drug abusers in Ireland

Serological and molecular analyses of a cohort of HIV-1-infected intravenous drug abusers (IVDAs) (n = 103) in Dublin, Ireland have demonstrated that 15 of 103 (14.6%) were infected with HTLV-II, which is the highest infection rate yet recorded for any European country. Restriction fragment length polymorphism (RFLP) analysis of the env region of the provirus demonstrated that the infection involved only the HTLV-IIa subtype; the HTLV-IIb subtype was not detected. Phylogenetic analysis of the nucleotide sequences of the long terminal repeat (LTR) confirmed infection with the HTLV-IIa subtype, and demonstrated that the viruses clustered closely with HTLV-IIa isolates from North American IVDAs. Previous observations that IVDAs in southern Europe, specifically Spain and Italy, appear to be infected predominantly with the HTLV-IIb subtype, along with the present report and evidence that IVDAs in Sweden are infected with the HTLV-IIa subtype, suggest different origins of HTLV-II infection in Europe.

Sex difference in the relationship of calcium and magnesium excretion to glycaemic control in type 1 diabetes mellitus

In order to assess the variability and possible causes of calcium and magnesium losses in diabetes mellitus, urinary calcium and magnesium excretion were monitored six monthly over a 3-year period in 108 stable, type 1 diabetic patients who were having assessment of their clinical status and glycaemic control over the same period. In the patients studied the ranges of excretion of both calcium and magnesium were considerably wider than our non-diabetic reference ranges but the within subject variation in excretion was high. However, using mean values obtained over the study period, a direct relationship was observed between the excretion of both calcium and magnesium and HbA1 in female patients (P < 0.01) but not in males who had similar HbA1 values. The urinary excretion of calcium and magnesium did not relate to any of the other clinical or biochemical indices measured, including body mass index, daily insulin dose, retinal status or albumin excretion. It is suggested that, in poorly controlled patients, females may have a greater risk than males of developing the complications associated with chronic calcium and magnesium loss.

The benefits of telephone-access medical consultation

A major disadvantage of rural medical practice is the limited reserve of consultative options. To determine the perceived clinical utility and educational impact of the West Virginia University Medical Access and Referral System (MARS), a 24-hour prompt telephone-consultation service, a mailed questionnaire was administered to 303 West Virginia clinicians who had used MARS for infectious disease problems. The overall questionnaire response rate was 62 percent. Callers included family practitioners (35%), medical specialists (32%), surgical specialists (13%), pediatricians (11%), obstetricians (5%), and nonphysicians (4%). Major referral questions posed were therapeutic (60%), diagnostic (48%), and epidemiologic (10%) in nature. On a scale of 1 (not useful) to 5 (very useful), survey responders rated the overall clinical usefulness of MARS as either a 4 (22%) or 5 (76%). Callers felt that MARS consultation assisted in accurate case diagnosis in 80 percent of cases, and aided in successful therapeutic management of 96 percent of cases. An educational benefit was reported by 96 percent of responders. Physicians located in more rural, underserved areas tended to use MARS to a greater degree than colleagues in more populated, medically accessible areas (P < 0.005). These findings suggest that an academic telephone-access consultation program can be a clinically relevant and educational consultative tool for practicing clinicians, especially those located in rural areas.

Modification of gibberellin production and plant development in Arabidopsis by sense and antisense expression of gibberellin 20-oxidase genes

Gibberellin (GA) 20-oxidase catalyses consecutive steps late in GA biosynthesis in plants. In Arabidopsis, the enzyme is encoded by a gene family of at least three members (AtGA20ox1, AtGA20ox2 and AtGA20ox3) with differential patterns of expression. The genes are regulated by feedback from bioactive GAs, suggesting that the enzymes may be involved in regulating GA biosynthesis. To investigate this, we produced transgenic Arabidopsis expressing sense or antisense copies of each of the GA 20-oxidase cDNAs. Over-expression of any of the cDNAs gave rise to seedlings with elongated hypocotyls; the plants flowered earlier than controls in both long and short days and were 25% taller at maturity. GA analysis of the vegetative rosettes showed a two- to threefold increase in the level of GA4, indicating that GA 20-oxidase normally limits bioactive GA levels. Plants expressing antisense copies of AtGA20ox1 had short hypocotyls and reduced rates of stem elongation. This was reflected in reduced levels of GA4 in both rosettes and shoot tips. In short days, flowering was delayed and the reduction in the rate of stem elongation was greater. Antisense expression of AtGA20ox2 had no apparent effects in long days, but stem growth in one transgenic line grown in short days was reduced by 20%. Expression of antisense copies of AtGA20ox3 had no visible effect, except for one transgenic line that had short hypocotyls. These results demonstrate that GA levels and, hence, plant growth and development can be modified by manipulation of GA 20-oxidase expression in transgenic plants.

Endothelial function in Marfan syndrome: selective impairment of flow-mediated vasodilation

BACKGROUND

The cardiovascular complications of Marfan syndrome arise due to alterations in the structural and functional properties of fibrillin, a constituent of vascular connective tissues. Fibrillin-containing microfibrils are closely associated with arterial endothelial cells, indicating a possible functional role for fibrillin in the endothelium. Plasma concentrations of endothelial cell products are elevated in Marfan subjects, which indirectly indicates endothelial dysfunction. This study directly assessed flow- and agonist-mediated endothelium-dependent brachial artery reactivity in Marfan subjects.

METHODS AND RESULTS

In 20 Marfan and 20 control subjects, brachial artery diameter, blood flow, and blood pressure were measured by ultrasonic wall tracking, Doppler ultrasound, and photoplethysmography, respectively. Measurements were taken during hand hyperemia (a stimulus for endothelium-derived nitric oxide [NO] release in the upstream brachial artery) and after sublingual administration of the endothelium-independent vasodilator nitroglycerin. In 9 Marfan and 6 control subjects, the above parameters were also assessed during intra-arterial infusions of acetylcholine and bradykinin (agonists that stimulate NO production) and NG-monomethyl-L-arginine (L-NMMA, an inhibitor of NO production). Flow-mediated responses differed markedly between Marfan and control subjects (-1.6+/-3.5% versus 6. 50+/-4.1%, respectively; P<0.0001), whereas nitroglycerin produced similar vasodilation (14.2+/-5.7% versus 15.2+/-7.8%; P=NS). Agonist-induced vasodilation to incremental intra-arterial infusions of acetylcholine and bradykinin were not significantly different between Marfan and control subjects, and intra-arterial L-NMMA produced similar reductions in brachial artery diameter in both groups.

CONCLUSIONS

These data demonstrate impaired flow-mediated but preserved agonist-mediated endothelium-dependent vasodilation in Marfan subjects and suggest preservation of basal NO release. Selective loss of flow-mediated dilation suggests a role for fibrillin in endothelial cell mechanotransduction.

Production of calcium-reduced milks using an ion-exchange resin

Ion exchange is used commercially in such processes as water softening, chemical purification, separation of ionic from non-ionic forms and analytical applications. Van Kreveld & van Minnen (1955) reported a method for the determination of Ca2+ and Mg2+ activity in milk using an ion-exchange resin. From this early work, it was established that with suitable resins exchange of salts was possible in milk, permeate and whey. This included the exchange of Ca and Mg from micelles by using Na+ or K+. Cationic resins of the Zerolit 236 type have been used successfully in the production of Ca-reduced single cream (Anderson et al. 1976). Such treatment prior to UHT processing was shown to increase physical stability when it was used as a coffee whitener. There is evidence that reduction of Ca2+ would also reduce the deposit formation that may occur during storage of UHT milk. Thus there is a need to establish commercial techniques to produce Ca-adjusted milks that could then be used as raw materials for industrial applications or product development work.

The present study investigated the use of ion exchange to reduce Ca in milk with particular reference to understanding the exchange of salts in Ca-reduced milk and the changes to some of its physical properties.

Contribution of the lactoperoxidase system to the keeping quality of pasteurized milk

The lactoperoxidase system is a naturally occurring antimicrobial system found in milk, with lactoperoxidase, thiocyanate and hydrogen peroxide as its components. The keeping quality of milk pasteurized at 72 degrees C for 15 s was found to be better than that of milk heated at 80 degrees C for 15 s. This agrees with previous findings and is usually attributed to heat shocking of spores. However, complete deactivation of lactoperoxidase occurred at 80 degrees C-15 s, whereas at 72 degrees C-15 s residual lactoperoxidase activity was approximately 70%, which may provide an alternative explanation. Higher levels of hypothiocyanite (the major antimicrobial agent produced by the lactoperoxidase system) were also detected in milk processed at 72 than at 80 degrees C, which supports the theory that the lactoperoxidase system has a role in the keeping quality of pasteurized milk. Of all the methods evaluated, titratable acidity and alcohol stability gave the most consistent estimates of keeping quality, while dissolved oxygen was a good indication of the onset of spoilage. Lactoperoxidase activity decreased with temperature more rapidly between 70 and 80 degrees C than is usual for an enzyme over a 10 deg C range.

Culture as metaphor: company culture and business strategy at Raleigh Industries, c. 1945-60

This study of Raleigh Industries, one of the leading bicycle manufactures in the world in the immediate post-war years, argues that its business strategy was in part shaped by a managerial commitment to a dominant company culture which was deeply embedded in Raleigh's history. Using the notion of culture as metaphor, the paper examines the way that core values in the company acted as a guide in the setting of organisational goals and, intended or unintended, impinged upon company performance. In many respects, the culture guided the company well, but our study shows a number of ambiguities, tensions and contradictions between culture and strategy which had negative effects on company behaviour. Thus, Raleigh's attachment to personal capitalism constrained its capacity expansion programme, and, while it adopted what appeared to be a progressive education and training policy, it in effect trained workers for the past rather than the future.

Endothelial function is impaired in fit young adults of low birth weight

OBJECTIVE

Non-insulin-dependent diabetes, hypertension and ischaemic heart disease, with insulin resistance, are associated with low birth weight (the 'Small Baby Syndrome'). Common to these adult clinical conditions is endothelial dysfunction. We tested the hypothesis that endothelial dysfunction could precede their development in those of low birth weight.

METHODS

Endothelial function was measured by ultrasonic 'wall-tracking' of flow-related brachial artery dilatation in fit 19-20 year old subjects randomly selected (blind to the investigators throughout the study) from low (< 2.5 kg) and normal (3.0-3.8 kg) birth weight subjects in the 1975-7 cohort of the Cardiff Births Survey and with no known cause for endothelial dysfunction.

RESULTS

Flow-related dilatation was impaired in low birth weight relative to normal birth weight subjects (median 0.04 mm [1.5%] [n = 22] cf. 0.11 mm [4.1%] [n = 17], p < 0.05; 0.04 mm [1.5%] [n = 15] cf. 0.12 mm [4.4%] [n = 12], p < 0.05 after exclusion of inadvertently included ever-smokers).

CONCLUSION

The findings suggest that endothelial dysfunction is a consequence of foetal malnutrition, consistent with contributing to the clinical features of the 'Small Baby Syndrome' in later adult life.

Hyperhomocysteinemia after an oral methionine load acutely impairs endothelial function in healthy adults

BACKGROUND

Elevated plasma homocysteine is a risk factor for arteriosclerosis, but a cause-and-effect relationship remains to be fully established. Endothelial dysfunction, an early event in the atherogenic process, has been shown to be associated with hyperhomocysteinemia in experimental and human studies. To further establish a direct relationship between changes in plasma homocysteine and endothelial dysfunction, we investigated whether moderate hyperhomocysteinemia induced by an oral methionine load would acutely impair flow-mediated endothelium-dependent vasodilatation in healthy adults.

METHODS AND RESULTS

Twenty-four healthy volunteers completed a randomized crossover study in which an oral methionine load (0.1 g/kg) was administered on 1 of 2 study days, 7 days apart. At each visit, plasma homocysteine and brachial artery endothelium-dependent and -independent dilatation were measured at baseline and at 4 hours. To further elucidate the temporal relationship between methionine, homocysteine, and endothelial function, an oral methionine load was administered in 10 subjects on a separate visit, and the time courses of plasma methionine, homocysteine, and flow-mediated brachial artery dilatation were measured at baseline and after 1, 2, 3, 4, and 8 hours. After oral methionine, plasma homocysteine increased from 7. 9+/-2.0 micromol/L at baseline to 23.1+/-5.4 micromol/L at 4 hours (P<0.0001, n=24) and was associated with a decrease in flow-mediated brachial artery dilatation from 0.12+/-0.09 to 0.06+/-0.09 mm (P<0. 05). The time course of the impairment of flow-mediated vasodilatation mirrored the time course of the increase in homocysteine concentration.

CONCLUSIONS

Oral methionine loading raises plasma homocysteine and impairs flow-mediated endothelium-dependent vasodilatation. This supports the view that homocysteine may promote vascular disease by inducing endothelial dysfunction.

Buprenorphine alters ethanol self-administration in rats: dose-response and time-dependent effects

Buprenorphine is a partial opioid agonist derived from thebaine and has high affinity for mu and kappa opioid receptors. The present study investigated dose-response (0.03, 0.15, 0.3, 3 mg/kg) and time-dependent effects of buprenorphine (1.5 or 4 h post-treatment) on EtOH self-administration in outbred Sprague-Dawley rats. Freely feeding and drinking rats were trained to initiate EtOH self-administration for 1 h daily using the ascending concentration procedure, wherein they were provided with increasing concentrations of EtOH at 2, 5, 7, 9 and 11% (v/v), respectively. Water was concurrently available with each concentration. Animals were maintained on a given concentration of EtOH for 5 days. By day 21, animals began their stabilization on the 11% regimen and remained on this concentration throughout the remainder of the study. EtOH and water consumption were recorded daily at both 10- and 60-min intervals. At 1.5 h post-buprenorphine, all test doses greatly suppressed both EtOH and water intake at the 10-min interval. At the 60-min interval, all but the lowest dose (0.03 mg/kg) significantly suppressed EtOH intake, while only the highest dose (3 mg/kg) suppressed water intake. In contrast to the suppressant profile observed at 1.5 h post-buprenorphine, at 4 h post-buprenorphine the lower doses (0.03 and 0.15 mg/kg) significantly increased EtOH intake while the higher doses (0.3 and 3 mg/kg) continued to suppress intake. None of the doses of buprenorphine altered water intake 4 h post-buprenorphine. The results support previous research demonstrating the utility of low doses of buprenorphine in suppressing behavior rewarded by a non-opioid drug.

Syndrome X and endothelial dysfunction

OBJECTIVE

Syndrome X (angina, normal coronary arteriogram and positive exercise test) remains an enigma with unexplained features and apparent conflicts of evidence. The present study addressed whether (i) the Syndrome is characterised by generalised flow-related endothelial dysfunction, (ii) myocardial thallium201 defects reflect myocardial or microvascular dysfunction, (iii) endothelial dysfunction and its consequences can be improved by oral L-arginine.

METHODS

Flow-mediated brachial artery dilatation was measured by ultrasonic 'wall-tracking' in 7 Syndrome X patients, further characterised as having thallium201 defects and no known cause of endothelial dysfunction, and a normal control group. Syndrome X patients entered a 4-week randomised double-blind placebo-controlled cross-over trial of oral L-arginine (7 g twice daily), with brachial artery studies, exercise tests and technetium99 tetrafosmin scans.

RESULTS

Flow-mediated dilatation was absent in Syndrome X vs. normal. Stress technetium99 tetrafosmin and thallium201 scans showed similar defects. Flow-mediated dilatation, symptom-limited exercise duration and peak oxygen consumption (VO2max) were increased but rate-pressure-product (RPP) and radionuclide defects were unchanged after L-arginine vs. placebo.

CONCLUSIONS

The study supports coronary microvascular rather than myocardial dysfunction and shows loss of flow-mediated dilatation in systemic arteries. Oral L-arginine improved flow-mediated dilatation, exercise capacity and VO2max (by ca. 17%) despite unchanged RPP. The findings support generalised endothelial dysfunction. The arginine effects imply NO-mediated improvement of skeletal muscle perfusion suggesting improved homogeneity of microvascular distribution.

Pain comparison after subcutaneous administration of single-dose formulation versus multidose formulation of epogen in hemodialysis patients

Subcutaneous (s.c.) injection is an approved route of administration for recombinant human erythropoietin (epoetin alfa). However, pain at the injection site with the single-dose formulation has limited its use. With the recent development of a multidose formulation containing benzyl alcohol as a preservative, anecdotal reports have emerged that suggest this product causes less stinging. Using a randomized, triple-blind, placebo-controlled crossover design, this study compared pain perception, intensity, and duration after s.c. injection with a multidose formulation versus single-dose formulation using visual analogue (VAS) and verbal descriptive pain scales (VDS). Twenty-eight hemodialysis patients received s.c. injections of placebo (normal saline) in one arm and either the multidose or single-dose formulation in the opposite arm. One week later, the subjects again received placebo in one arm and the other epoetin alfa formulation in the opposite arm. The VAS and VDS measurements were obtained at time 0 and then every 5 minutes for a period of 30 minutes. Results showed a statistically significant difference in pain perception between formulations at times 0, 10, and 15 minutes for both the VAS and VDS. In conclusion, there was a significant difference in pain perception between formulations with the multidose formulation causing less pain than the single-dose formulation. However, it should be noted that several patients reported no pain with the single-dose formulation. This indicates that individual patient response could be considered when deciding which formulation to use, although it may be difficult to implement an error-free distribution and administration system using the two different formulations.

Effects of sulphydryl- and non-sulphydryl-containing ACE inhibitors on left ventricular relaxation in the isolated guinea pig heart

ACE inhibitors exert both acute and chronic beneficial effects on cardiac function (e.g remodelling, diastolic dysfunction). We have previously reported that the ACE inhibitor captopril induces selective left ventricular (LV) relaxant effects in the isolated ejecting guinea pig heart. The aim of the present study was to further investigate the mechanism of the captopril-induced changes in early LV relaxation by comparing the effects of two sulphydryl and two non-sulphydryl containing ACE inhibitors in the same experimental preparation. Isolated ejecting guinea pig hearts were studied under conditions of constant loading and heart rate. LV pressure was monitored by a 2F micromanometer-tipped catheter transducer inserted in the LV cavity. The sulphydryl-containing ACE inhibitors captopril and zofenaprilat enhanced early LV relaxation, whereas the non-sulphydryl-containing ACE inhibitors lisinopril and quinaprilat did not. The effects of captopril and zofenaprilat were attenuated both by the nitric oxide-scavenger haemoglobin and the bradykinin B2-kinin receptor antagonist HOE 140. Neither the oxygen free-radical scavenger superoxide dismutase nor the sulphydryl-containing compound N-acetyl cysteine administered together with lisinopril had any effect on LV relaxation. These data demonstrate that inhibition of intra-cardiac ACE activity may acutely modulate LV relaxation through increased activity of the bradykinin-nitric oxide pathway. The presence of a sulphydryl group on the relevant ACE inhibitor appears to be essential for this LV relaxant effect.

Influence of clinical mastitis during early lactation on reproductive performance of Jersey cows

The purpose of this study was to determine the influence of clinical mastitis on reproductive performance of high producing Jersey cows. Cows (n = 102) with clinical mastitis during the first 150 d of lactation were evaluated. Groups were balanced according to lactation number and days of lactation and sub-divided as follows: group 1, clinical mastitis before first artificial insemination (AI) (n = 48); group 2, clinical mastitis between first AI and pregnancy (n = 14); group 3, clinical mastitis after confirmed pregnancy (n = 40); and group 4, control cows (n = 103) with no clinical mastitis. No differences in reproductive performance were detected because of milk production or mastitis caused by Gram-positive or Gram-negative pathogens. The number of days to first AI was significantly greater for cows with clinical mastitis before first AI (93.6 d) than for all other groups (71.0 d). Artificial inseminations per conception were significantly greater for cows with clinical mastitis after first AI (2.9) than for cows with clinical mastitis before first AI (1.6), cows with no clinical mastitis, or cows with clinical mastitis after confirmed pregnancy (1.7). The number of days to conception for cows with clinical mastitis after first AI (136.6 d) was significantly greater than that for control cows and that for cows that developed clinical mastitis after confirmed pregnancy (92.1 d). Clinical mastitis during early lactation markedly influenced reproductive performance of Jersey cows.

Bran: may irritate irritable bowel

The irritable gut is known to be hypersensitive, and it is reasonable to suspect that patients with the disorder might be hyperreactive to agents that stimulate or irritate it. This appears to be a possible explanation for the adverse effects of bran on hospital patients with this disorder, but we do not yet know how this product affects community IBS sufferers. We cannot ignore the fact that fiber and bran have major beneficial effects in other areas, not least in the reduction of colonic carcinoma. In conclusion, it is probably best to recommend that patients with IBS be left to judge for themselves whether bran helps or exacerbates their symptoms, but there is enough evidence to suggest that the current dogma of routinely treating all IBS sufferers with bran should be challenged. Proprietary sources of fiber, such as ispaghula, may be more appropriate for those IBS subjects (for example, constipated) for whom fiber supplementation is believed justified.

Epidemic of pediatric deaths from acute renal failure caused by diethylene glycol poisoning. Acute Renal Failure Investigation Team

CONTEXT

Contaminated pharmaceutical products can result in substantial morbidity and mortality and should be included in the differential diagnosis of deaths of unknown origin.

OBJECTIVE

To investigate an outbreak of deaths among children from acute renal failure in Haiti to determine the etiology and institute control measures.

DESIGN

Case-control study, cohort study, and laboratory toxicologic evaluation.

SETTING

Pediatric population of Haiti.

PARTICIPANTS

Cases were defined as Haitian residents younger than 18 years with idiopathic anuria or severe oliguria for 24 hours or longer. Febrile hospitalized children without renal failure were enrolled as control subjects.

MAIN OUTCOME MEASURE

The odds of exposure to suspected etiologic agents among cases and controls.

RESULTS

We identified 109 cases of acute renal failure among children. The clinical syndrome included renal failure, hepatitis, pancreatitis, central nervous system impairment, coma, and death. Of 87 patients with follow-up information who remained in Haiti for treatment, 85 (98%) died; 3 (27%) of 11 patients transported to the United States for intensive care unit management died before hospital discharge. A locally manufactured acetaminophen syrup was highly associated with disease (odds ratio, 52.7; 95% confidence interval, 15.2-197.2). Diethylene glycol (DEG) was found in patients' bottles in a median concentration of 14.4%. The median estimated toxic dose of DEG was 1.34 mL/kg (range, 0.22-4.42 mL/kg). Glycerin, a raw material imported to Haiti and used in the acetaminophen formulation, was contaminated with 24% DEG.

CONCLUSIONS

An epidemic of severe systemic toxicity and deaths from DEG-contaminated acetaminophen syrup occurred in Haiti. Good manufacturing practice regulations should be used by all pharmaceutical manufacturers to prevent such tragedies.

Identification and molecular characterization of human T lymphotropic virus type II infections in intravenous drug abusers in the former South Vietnam

Previous serological studies have demonstrated that some 60% of intravenous drug abusers (IVDAs) in urban areas of the former South Vietnam are infected with HTLV-II. In the present report we have attempted to characterize the viruses using restriction fragment length polymorphism (RFLP) and nucleotide sequence analysis of the provirus long terminal repeat (LTR) region. RFLP analysis of nine samples demonstrated that all were infected with the HTLV-IIb subtype. The HTLV-IIa subtype was not detected. Phylogenetic analysis of the nucleotide sequences demonstrated that the viruses clustered closely with HTLV-IIb isolates present in IVDAs from the New York City area. The present molecular analysis together with the previously reported absence of HTLV-II infection in North Vietnam supports the view that HTLV-II may have been introduced from the United States to this part of Asia by military personnel during the Vietnam conflict.

Redistribution of von Willebrand factor in porcine carotid arteries after balloon angioplasty

von Willebrand factor (VWF) is a well-characterized multimeric glycoprotein present in platelets and plasma and synthesized by vascular endothelial cells and megakaryocytes. Its role in platelet-vessel wall interactions has been studied extensively, but its involvement in intravascular events after balloon angioplasty has not been clarified. VWF antigen is not present in porcine arterial endothelium (except for the pulmonary artery) but is readily detected in porcine venous endothelial cells. We have examined the localization of VWF in porcine vessel walls during neointima formation after bilateral carotid balloon-angioplasty. Endothelium was denuded by balloon injury but regenerated by 7 days and was fully confluent by 42 days. VWF was detected at the site of injury in localized, adherent platelet aggregates at 10 minutes after angioplasty that were not present at later time points. A well-demarcated homogeneous layer of VWF was observed on the luminal surface from 30 minutes to day 7, but there was a progressive shift of positive staining from the lumen to the outer media from days 1 to 7. VWF was also strongly detected at sites proximal and distal to the balloon injury from 30 minutes to day 7, although endothelial disruption was minimal and the monolayer remained substantially intact at these sites. Regrowing endothelial cells appeared to contain granular VWF from days 12 to 21, but this was not readily evident at later time points. The results suggest that balloon injury is associated with deposition and medial absorption of plasma or platelet VWF in this porcine model over a time period that precedes and overlaps vascular smooth muscle proliferation and endothelial recoverage. The findings provide evidence to support the concept of a wider role for VWF in tissue injury responses.

Parental perceptions of barriers to childhood immunization: results of focus groups conducted in an urban population

The current US immunization rates for 2 year olds are approximately half of the goal set for the year 2000. Research studies have focused primarily on the perception of health care providers in the identification of barriers and benefits to childhood immunization. While health care providers are an important part of the immunization delivery process, the perceptions of parents are also important. In this study, qualitative methods were used to explore perceived parental barriers to childhood immunization delivery. Twelve focus groups comprising White, African-American, Hispanic, urban and non-urban people were conducted at a variety of sites, including clinics, churches, schools and work sites. The results indicated that time off from work, access to well-child care and difficulty understanding the complexity of the immunization schedule were seen as barriers to adhering to an immunization schedule. Participants emphasized problems in taking time off from work to get immunizations, sometimes without pay, and expressed fears that doing so would jeopardize promotions and raises. While some of the parental perceptions were similar to those identified in studies of health care providers in the literature, many were not. This study emphasizes the importance of gathering information from parents as well as from health care providers.

Evaluation of three methods for improving mammography rates in a managed care plan

INTRODUCTION

Mammography has been shown to reduce breast cancer mortality among women 50 and older. Although mammography rates are increasing nationally, this effective screening tool remains underused. This study was conducted among 395 women who were members of a network model health maintenance organization (HMO) in Philadelphia in order to determine which of three methods was most effective in increasing mammography rates: (1) a birthday card reminder only (the standard method); (2) a personalized letter from the medical director and materials promoting mammography; and (3) a multicomponent phone call incorporating a reminder, counseling, and scheduling of appointments. An additional goal was to determine whether the interventions were more or less effective depending on a woman's readiness to get a mammogram, as measured by stage of change.

METHODS

Eligible women were randomized into one of three treatment groups described earlier. Mammography rates were calculated on the basis of a claims review and follow-up phone interviews after a period of six months.

RESULTS

Women who received the telephone intervention were most likely to obtain a mammogram (28%); followed by the group that received the birthday card only (15%), and those who received the mailed intervention (9%).

CONCLUSIONS

These results indicate that a multicomponent phone intervention is significantly effective in promoting mammography in managed health care plan members. An analysis by women's stage of change found a difference in the effectiveness of the three interventions among contemplators only.

A novel SNARE complex implicated in vesicle fusion with the endoplasmic reticulum

Intracellular vesicular traffic is controlled in part by v- and t-SNAREs, integral membrane proteins which allow specific interaction and fusion between vesicles (v-SNAREs) and their target membranes (t-SNAREs). In yeast, retrograde transport from the Golgi complex to the ER is mediated by the ER t-SNARE Ufe1p, and also requires two other ER proteins, Sec20p and Tip20p, which bind each other. Although Sec20p is not a typical SNARE, we show that both it and Tip20p can be co-precipitated with Ufe1p, and that a growth-inhibiting mutation in Ufe1p can be compensated by a mutation in Sec20p. Furthermore, Sec22p, a v-SNARE implicated in forward transport from ER to Golgi, co-precipitates with Ufe1p and Sec20p, and SEC22 acts as an allele-specific multicopy suppressor of a temperature-sensitive ufe1 mutation. These results define a new functional SNARE complex, with features distinct from the plasma membrane and cis-Golgi complexes previously identified. They also show that a single v-SNARE can be involved in both anterograde and retrograde transport, which suggests that the mere presence of a particular v-SNARE may not be sufficient to determine the preferred target for a transport vesicle.

Antibiotic residues and prevalence of mastitis pathogen isolation in heifers during early lactation following prepartum antibiotic therapy

The present study was conducted to determine if antibiotic treatment of heifer mammary glands earlier in the prepartum period reduced the occurrence of residues in milk without compromising efficacy in treatment of intramammary infections. Heifers were assigned randomly to two groups: 1. untreated negative control (n = 42); and 2. intramammary infusion of 200 mg cephapirin sodium (n = 40) 14 days prior to expected calving. Mammary secretions were collected before treatment and during early lactation, and were analyzed for residues by the Bacillus stearothermophilus disc assay. Only four of 127 samples (3.1%) obtained from cephapirin-treated mammary glands at 3 days after calving were positive for residues and most (three of four) were from a heifer that calved within 3 days of treatment. Mammary secretions were also collected before treatment, and at 3 and 30 days after calving for microbiological evaluation. For untreated control heifers, mastitis pathogens were isolated from 67.3% of samples obtained from mammary glands 14 days prior to expected calving, 55.6% obtained 3 days after calving and 36.4% of samples obtained 30 days postpartum. A similar percentage of samples (63.8%) was positive for mastitis pathogens at 14 days before expected calving prior to antibiotic treatment. However, only 15.1% of samples obtained at 3 days after calving and 7.9% of samples obtained 30 days postpartum from mammary glands of antibiotic-treated heifers contained mastitis pathogens. Coagulase-negative staphylococci were isolated most frequently. Intramammary infusion of antibiotics earlier in the prepartum period markedly reduced the occurrence of residues in milk during early lactation without affecting efficacy.

Regulation of left ventricular relaxation in the isolated guinea-pig heart by endogenous endothelin

OBJECTIVE

TO examine the effects of endogenous endothelin-1 on cardiac contraction in the isolated heart using endothelin receptor antagonists.

METHODS

Isolated ejecting guinea-pig hearts were perfused with Krebs buffer (1 microM indomethacin) at 37 degrees C, constant loading and heart rate, and high-fidelity left ventricular pressure was monitored by an apical 2F Millar catheter. The effects of the following interventions on left ventricular performance and coronary flow were determined: (a) no treatment (i.e., time controls) (n = 8); (b) the specific ETA receptor antagonist, BQ123 (1 microM, n = 8); (c) the specific ETB receptor antagonist, IRL 1038 (0.1 microM, n = 4; 1 microM, n = 6); (d) exogenous endothelin-1 (0.01 nM, n = 6; 0.1 nM, n = 6); (e) the specific ETB receptor agonist, BQ3020 (5 nM, n = 8).

RESULTS

All parameters were stable in control (untreated) hearts. BQ123 induced progressive acceleration of early left ventricular pressure decline and a fall in left ventricular end-diastolic pressure with no effect on peak left ventricular pressure, dP/dtmax, stroke volume or coronary flow. IRL 1038 had no effect on any of these parameters. In contrast, exogenous endothelin-1 exerted potent vasoconstrictor effects associated with a fall in peak left ventricular pressure, dP/dtmax and stroke volume. Similar changes were observed with BQ3020. Concentrations of endothelin-1 < 0.1 nM, which had no vasoconstrictor effect, produced no change in LV function.

CONCLUSIONS

These data indicate that basal intracardiac release of endothelin-1 significantly delays LV relaxation in the isolated guinea-pig heart, but has no effect on coronary flow. The contrasting effects of endogenous endothelin-1 (elicited by BQ123) and exogenous endothelin-1 are likely to reflect differences in their site of action and in their effective concentrations at these sites.

The cardiac endothelium: cardioactive mediators

Endothelial cells within the heart release a number of substances that modulate myocardial contractile function. These agents include nitric oxide, endothelin, prostanoids, adenylpurines, and other substances that have so far been characterized only in bioassay studies. A notable feature of many of these agents is that they influence contractile behavior predominantly by modifying cardiac myofilament properties rather than altering cytosolic Ca2+ transients. A consequence of this subcellular action is often a disproportionate effect on myocardial relaxation and diastolic tone. The paracrine modulation of cardiac myocyte function by endothelial cell factors is likely to be an important mechanism contributing to the overall regulation of cardiac contractile function, both physiologically and in pathological states.

Identification of three C20-gibberellins: GA97 (2 beta-hydroxy-GA53), GA98 (2 beta-hydroxy-GA44) and GA99 (2 beta-hydroxy-GA19)

Three new C20-gibberellins, GA97 (2 beta-hydroxy-GA53), GA98 (2 beta-hydroxy-GA44) and GA99 (2 beta-hydroxy-GA19), have all been isolated from spinach, GA97 also from tomato root cultures and pea pods, and GA98 from maize pollen. The structures of these compounds were established by GC-mass spectrometric comparisons of the trimethylsilylated methyl esters with authentic samples prepared from gibberellic acid (GA3).

SNARE-mediated retrograde traffic from the Golgi complex to the endoplasmic reticulum

Operation of the secretory pathway in eukaryotic cells requires the selective docking and fusion of transport vesicles with the appropriate target organelle. This is mediated in part by integral membrane proteins termed v-SNAREs (on vesicles) and t-SNAREs (on the target membranes). We describe a novel yeast t-SNARE that resides on the endoplasmic reticulum and mediates retrograde traffic from the Golgi complex. Mutation of this protein prevents both the HDEL receptor and a membrane protein bearing a dibasic retrieval signal from recycling to the endoplasmic reticulum. Forward traffic is also blocked, but only indirectly. Comparison with other yeast mutants indicates that Sec21p (gamma-COP) and Sec20p (an endoplasmic reticulum membrane protein) are also involved primarily, if not exclusively, in retrograde transport.

Alcohol reinforcement and neuropharmacological therapeutics

The pleasant subjective effects produced by alcohol undoubtedly reinforce drinking behaviour. Alcohol positively reinforces or rewards drinking by producing a mild euphoria. Alcohol also has anxiolytic effects that negatively reinforce drinking. The reinforcing effects of alcohol are mediated by several neurochemical systems, with dopamine and serotonin playing major roles in reward and the gamma-aminobutyric acid-benzodiazepine receptor system playing a major role in negative reinforcement. Research from our laboratory suggests that the behavioural effects of alcohol change when blood alcohol levels are changing and that these changes correspond to alterations of specific neurochemical systems. Behavioural activation and reward effects appear to occur as blood alcohol concentrations (BACs) increase. Depressive and aversive effects of alcohol occur during the period when BACs decrease. The observed correlation between behavioural and neuropharmacological changes and alcohol consumption suggest that alcohol produces a unique cascade over time that may provide clues to its long-sought specific mechanisms of action. In alcohol-dependent individuals, chronic exposure to alcohol may alter the function and communication between the liver, brain and other vital organ systems involved in hunger and the maintenance of nutrition. Under such conditions, the importance of alcohol in the diet may be enhanced such that hunger signals in the alcohol-dependent individual motivate the consumption of alcohol. Therefore, hunger for alcohol may provide an additional source of reinforcement. Endogenous opioid mechanisms may be important in this form of alcohol reinforcement.

Alcohol reinforcement and neuropharmacological therapeutics

The pleasant subjective effects produced by alcohol undoubtedly reinforce drinking behaviour. Alcohol positively reinforces or rewards drinking by producing a mild euphoria. Alcohol also has anxiolytic effects that negatively reinforce drinking. The reinforcing effects of alcohol are mediated by several neurochemical systems, with dopamine and serotonin playing major roles in reward and the gamma-aminobutyric acid-benzodiazepine receptor system playing a major role in negative reinforcement. Research from our laboratory suggests that the behavioural effects of alcohol change when blood alcohol levels are changing and that these changes correspond to alterations of specific neurochemical systems. Behavioural activation and reward effects appear to occur as blood alcohol concentrations (BACs) increase. Depressive and aversive effects of alcohol occur during the period when BACs decrease. The observed correlation between behavioural and neuropharmacological changes and alcohol consumption suggest that alcohol produces a unique cascade over time that may provide clues to its long-sought specific mechanisms of action. In alcohol-dependent individuals, chronic exposure to alcohol may alter the function and communication between the liver, brain and other vital organ systems involved in hunger and the maintenance of nutrition. Under such conditions, the importance of alcohol in the diet may be enhanced such that hunger signals in the alcohol-dependent individual motivate the consumption of alcohol. Therefore, hunger for alcohol may provide an additional source of reinforcement. Endogenous opioid mechanisms may be important in this form of alcohol reinforcement.

Feed-back regulation of gibberellin biosynthesis and gene expression in Pisum sativum L

Treatment of tall and dwarf (3 beta-hydroxylase impaired) genotypes of pea (Pisum sativum L.) with the synthetic, highly active gibberellin (GA), 2,2-dimethyl GA4, reduced the shoot contents of C19-GAs, including GA1, and increased the concentration of the C20-GA, GA19. In shoots of the slender (la crys) mutant, the content of C19-GAs was lower and GA19 content was higher than in those of the tall line. Metabolism of GA19 and GA20 in leaves of a severe (na) GA-deficient dwarf mutant was reduced by GA treatment. The results suggest feed-back regulation of the 20-oxidation and 3 beta-hydroxylation reactions. Feed-back regulation of GA 20-oxidation was studied further using a cloned GA 20-oxidase cDNA from pea. The cDNA, Ps074, was isolated using polymerase chain reaction with degenerate oligonucleotide primers based on pumpkin and Arabidopsis 20-oxidase sequences. After expression of this cDNA clone in Escherichia coli, the product oxidized GA12 to GA15, GA24 and the C19-GA, GA9, which was the major product. The 13-hydroxylated substrate GA53 was similarly oxidized, but less effectively than GA12, giving mainly GA44 with low yields of GA19 and GA20. Ps074 hybridized to polyadenylated RNA from expanding shoots of pea. Amounts of this transcript were less in the slender genotype than in the tall line and were reduced in GA-deficient genotypes by treatment with GA3, suggesting that there is feed-back regulation of GA 20-oxidase gene expression.

Endothelial control of arterial distensibility is impaired in chronic heart failure

BACKGROUND

Vascular tone is a determinant of conduit artery distensibility. The aim of this study was to establish whether endothelium-derived relaxing factor (EDRF) influences the distensibility of conduit arteries and whether endothelium-mediated increases in distensibility are impaired in chronic heart failure (CHF).

METHODS AND RESULTS

Conduit artery distensibility was measured by two methods in healthy subjects and in nine patients with CHF caused by dilated cardiomyopathy. In the first method, pulse-wave velocity (PWV) was measured in the right common iliac artery at rest and during local infusions of acetylcholine (10(-7) to 10(-5) mol/L) or adenosine (2 x 10(-7) to 2 x 10(-5) mol/L), with correction for systemic effects. Acetylcholine induced concentration-dependent local reductions of PWV in healthy subjects (-5%, -15%, and -26%) but not in CHF patients (3%, 1%, -4%, P < .01), whereas adenosine induced similar reductions of PWV in healthy subjects and CHF patients. In the second method, brachial artery diameter, blood flow, and blood pressure were measured noninvasively by high-resolution ultrasound, continuous-wave Doppler, and photoplethysmography during reactive hyperemia in the hand and after sublingual glyceryl trinitrate (GTN, 400 micrograms). Hyperemic flow, similar in healthy subjects and CHF patients, was associated with increases in diameter and distensibility in healthy subjects (8.8% and 18.4%, respectively) but not in CHF patients (0.3% and -4.5%), whereas GTN induced similar effects in healthy subjects and CHF patients.

CONCLUSIONS

These data indicate that conduit artery distensibility is increased by acetylcholine and increased blood flow in healthy subjects but not in CHF patients, whereas the effects of adenosine and GTN on distensibility are preserved in CHF patients. This implies that EDRF-mediated increases in distensibility are impaired in CHF patients, thus adding to cardiac work.

Enhancement of left ventricular relaxation in the isolated heart by an angiotensin-converting enzyme inhibitor

BACKGROUND

ACE inhibitors exert both acute and chronic beneficial effects on cardiac function (eg, remodeling, diastolic dysfunction) in experimental studies and in patients. They inhibit the formation of angiotensin II as well as the degradation of endogenous bradykinin. We recently reported that bradykinin induces selective left ventricular (LV) relaxant effects in isolated hearts via the release of nitric oxide. The present study examined the direct effects of interaction between the ACE inhibitor captopril and endogenous bradykinin on cardiac contractile function.

METHODS AND RESULTS

Isolated ejecting guinea pig hearts were studied under conditions of constant loading and heart rate. LV pressure was monitored by a 2F micromanometer-tipped catheter. Captopril (1 mumol/L, n = 9) caused a progressive acceleration of LV relaxation without significantly affecting early systolic parameters (eg, LV dP/dtmax) or coronary flow. These effects were inhibited by the nitric oxide scavenger hemoglobin (1 mumol/L, n = 5) or by the B2-kinin receptor antagonist HOE140 (10 nmol/L, n = 5). In the presence of captopril, bradykinin (0.1 nmol/L, n = 6) markedly accelerated LV relaxation (significantly more than captopril alone), whereas bradykinin alone (0.1 nmol/L, n = 6) had no effect.

CONCLUSIONS

These data indicate that the ACE inhibitor captopril causes an acute and selective enhancement of LV relaxation independent of changes in coronary flow, probably via an endogenous bradykinin/nitric oxide pathway.

Endothelial inhibition of myofilament calcium response in intact cardiac myocytes

Recent studies suggest that factors released by endothelial cells can modify contraction of isolated cardiac preparations. We compared the effects of 1) coronary effluent collected from Langendorff-perfused rat hearts and 2) cultured vascular endothelial cell superfusate on isolated fura 2-loaded rat ventricular cardiac myocytes. Coronary and cultured cell effluent produced similar effects. Isotonic contraction amplitude was reduced by 31.6 +/- 2.6 and 70.2 +/- 9.1%, respectively; myocyte diastolic length increased by 0.8 +/- 0.2 and 1.5 +/- 0.4 microns, and time to 50% relaxation fell by 6.2 +/- 1.8 and 10.1 +/- 2.0% (all P < 0.05; n = 29 and 15 myocytes, respectively). A small fall in the amplitude of the intracellular Ca2+ transient was observed (8.5 +/- 1.5 and 10.9 +/- 3.5%, respectively; both P < 0.01), insufficient to account for the reduction in twitch amplitude. In intact myocytes tetanized in the presence of thapsigargin, the steady-state myofilament response to Ca2+ was reduced by coronary and cultured cell effluent. These results suggest that both coronary endothelial cells in situ and cultured endothelial cells tonically release a factor(s) that reduces myofilament Ca2+ response.

Kinetics of smooth muscle cell proliferation and intimal thickening in a pig carotid model of balloon injury

Restenosis as a result of neointimal smooth muscle cell accumulation is an important limitation to the effectiveness of balloon angioplasty as a treatment for end-stage atherosclerosis. Quantitative animal models allow the definition of pathophysiological mechanisms and the evaluation of new therapeutic strategies. In this study we quantified the time course of neointima formation by morphometry, and smooth muscle cell (SMC) proliferation by immunocytochemistry for proliferating cell nuclear antigen (PCNA), in the pig carotid artery 0-28 days following balloon injury. This led to two distinct kinds of injury observed also in clinical studies, namely medial dilatation or deep medial tearing with rupture of the internal elastic lamina. Dilatation injury alone led to medial enlargement and neointima formation by 7 days, which did not increase further up to 28 days. Medial enlargement was similar following rupture of the internal elastic lamina; however the sum of neointima formation plus the area of medial repair ('neomedia') increased progressively up to 21 days after balloon injury. Balloon injury increased the PCNA index of smooth muscle cells in the media underlying an intact internal elastic lamina maximally after 3 days. The PCNA index in the neointima and especially in the neomedia was greater and maximal after 7 days. Endothelial regrowth occurred by 21 days in the presence or absence of medial tears. Our results establish a quantitative pig model of balloon injury which will allow the assessment of new therapeutic strategies directed at two clinically relevant types of injury. Medial tearing is associated with an enhanced and localized proliferative response and may therefore be especially important in human restenosis.

Effects of the benzodiazepine inverse agonist RO19-4603 on the maintenance of tolerance to a single dose of ethanol

The time course of the novel benzodiazepine inverse agonist, RO19--4603 (0.075 or 0.150 mg/kg) in antagonizing the depressant effects of ethanol (EtOH) (0.50, 1.0 and 1.5 g/kg) and the development of tolerance on locomotor behaviors (e.g., ambulatory count, total distance and stereotypy count) were investigated in Sprague-Dawley rats given EtOH injections spaced at 24-hr intervals. A single dose of RO19--4603 prevented the development of tolerance to the 0.50- and 1.0-g/kg EtOH doses 24-hr post-RO19--4603 administration on most locomotor behaviors. On Day 1, the 0.150-mg/kg RO19--4603 dose prevented the reduction of motor behaviors after the 1.0- and 1.5-g/kg EtOH doses, whereas the 0.075-mg/kg RO19--4603 dose prevented the reduction of motor behaviors only after the 1.5-g/kg EtOH dose. The 0.075- and 0.150-mg/kg RO19--4603 doses also prevented the EtOH-induced reduction of motor behaviors after the 1.5-g/kg EtOH dose 24-hr post-RO19--4603 administration. RO19--4603 was without effect on activity when given alone. These data suggest that the motor impairing effects of EtOH and the development of tolerance to them may involve gamma-aminobutyric acidA-benzodiazepine receptor mechanisms that when occupied, even briefly by certain benzodiazepine inverse agonists, produce long-lasting effects on locomotion and tolerance.

The effects of exogenous nitric oxide on smooth muscle cell proliferation following porcine carotid angioplasty

OBJECTIVES

Nitric oxide reduces platelet adhesion and platelet-thrombus formation following angioplasty and inhibits smooth muscle cell (SMC) proliferation in vitro. In this study we investigated the effects of the nitric oxide donor molsidomine on SMC proliferation and intimal growth following experimental angioplasty.

METHODS

Bilateral carotid angioplasty was performed in 24 anesthetized pigs. Animals were randomized to receive oral molsidomine (whose active metabolite is SIN-1; 0.3 mg/kg every 8 h; n = 12) or placebo (n = 12) for 48 h before angioplasty and until the arteries were removed either 7 or 21 days (n = 12 each group) later. SMC proliferation was quantified by immunocytochemical staining with an antibody to the proliferating cell nuclear antigen (PCNA) and morphometric changes by computerized planimetry. SMC's were identified by alpha-actin staining.

RESULTS

After 3 weeks treatment with molsidomine there was a significant prolongation in bleeding time [mean +/- SEM] (151 +/- 6 to 187 +/- 7 s. P < 0.01) and a sustained increase in arterial wall cyclic GMP (6.57 +/- 1.29 to 13.24 +/- 1.02 pmol/mg protein, P < 0.05). Molsidomine significantly reduced intimal proliferation when compared with placebo in arteries with an intact internal elastic lamina at 7 days (4.3 +/- 0.7 vs. 9.6 +/- 1.9 PCNA index, P < 0.005) and medial proliferation at 7 days (2.4 +/- 0.2 vs. 4.2 +/- 0.7 PCNA index, P < 0.05) and at 21 days (1.3 +/- 0.1 vs. 1.9 +/- 0.2 PCNA index, P < 0.05) after angioplasty. In arteries with rupture of the internal elastic lamina, intimal and medial SMC proliferation were similar in molsidomine- and placebo-treated animals. Intimal cell number and intimal area were uninfluenced by treatment with molsidomine in either the presence or absence of rupture of the internal elastic lamina.

CONCLUSIONS

These results show for the first time that exogenous nitric oxide inhibits SMC proliferation following balloon angioplasty in vivo. The antiproliferative effects of nitric oxide are overwhelmed when injury is severe and are not associated with a reduction in intimal thickening. The inhibitory effects of nitric oxide on platelet adhesion and SMC proliferation identify a possible role for high local concentrations of nitric oxide to modify the vascular response to balloon angioplasty.

The influence of endothelium-derived nitric oxide on myocardial contractile function

Nitric oxide released by cardiac endothelial cells modulates myocardial contractile function through elevation of intracellular 3',5'-cyclic guanosine monophosphate (cGMP). In the absence of agonist stimulation, nitric oxide typically enhances myocardial relaxation and reduces diastolic tone, without significantly altering the rate of force or pressure development. This pattern of effect is observed with nitric oxide or with cGMP analogues in isolated rat cardiac myocytes, isolated ferret papillary muscle preparations, and isolated ejecting guinea-pig hearts. In human subjects studied at cardiac catheterisation, low-dose bicoronary infusions of sodium nitroprusside or of substance P induce similar effects on left ventricular systolic and diastolic function. These changes may benefit from cardiac filling and coronary perfusion by increasing the diastolic interval, reducing extravascular compressive forces and increasing the driving pressure for filling, e.g., during exercise. Nitric oxide may also modulate inotropic and chronotropic responses to beta-adrenergic stimulation. Under pathological conditions, overproduction of nitric oxide by an inducible nitric oxide synthase may be detrimental for contractile function. Dysfunction of the constitutive nitric oxide pathway could also contribute to pathophysiology, e.g., in conditions characterised by diastolic dysfunction. The paracrine nitric oxide pathway is likely to be an important regulator of cardiac contractile function, acting in concert and interacting with other regulatory pathways.

A SNARE-like protein required for traffic through the Golgi complex

The secretory pathway of eukaryotic cells comprises several distinct membrane-bound compartments which are interconnected by transport vesicles that pinch off from one membrane and fuse with the next. Targeting of these vesicles is mediated in part by interactions between integral membrane proteins on the vesicles and target organelles (soluble NSF attachment protein receptors (SNAREs)), termed v-SNAREs and t-SNAREs, respectively. SNAREs required for endoplasmic reticulum (ER)-Golgi transport and for fusion of vesicles with the plasma membrane are already known. Here we identify two yeast membrane proteins that show genetic interactions with Sed5p, which is the t-SNARE for ER-Golgi traffic. One of these membrane proteins, Sft1p, is structurally similar to the known v-SNAREs and is required for transport from an early to a later Golgi compartment. Our results indicate that a single t-SNARE can control more than one transport step, and provide the first candidate for a SNARE involved in intra-Golgi traffic.

Power spectral analysis of the foetal magnetocardiogram

The results of power spectral analysis of foetal magnetocardiographic (FMCG) data, acquired using a DC-SQUID-based system, are reported. Similar analyses have been previously reported using foetal electrocardiographic data, but it is believed that our work represents one of the first attempts to analyse, in the frequency domain, the magnetic fields produced by foetal cardiac activity. Analysis of the data in this way may enable the integrity of the foetal nervous system, and thus the status of the foetus as a whole, to be monitored and evaluated during a significant part of the antenatal period. The results obtained are discussed with reference to the probable underlying physiological mechanisms. This preliminary study highlights some of the advantages of FMCG as a novel, non-invasive technique for obtaining clinically useful information. Fourier analysis of the FMCG data is likely to yield new information, not only about cardiac function but also about the foetal central nervous system.

Observations on the effect of raw milk quality on the keeping quality of pasteurized milk

Raw milk was stored for up to 14 d at 4 degrees C and pasteurized on days 1, 3, 4, 7, 9 and 14. Precautions were taken to eliminate post-pasteurization contamination. The pasteurized milks were stored at 4 degrees C and analysed at weekly intervals for standard plate counts (SPC), psychotrophic counts (PC) and aerobic spore counts (ASC). The initial raw milk quality was very good and the keeping quality of all the pasteurized milks tested was greater than 22 d. In some cases the milk still had acceptable SPC after 42 d storage, which shows the keeping quality that can be achieved when the process is well controlled. However, the best keeping quality resulted from milk pasteurized on the third and fourth days. Even milk pasteurized on the seventh and ninth had superior keeping quality to that pasteurized on the first day. The lactoperoxidase anti-microbial system in raw milk may be most active around days 3 and 4.

Modulation of left ventricular relaxation in isolated ejecting heart by endogenous nitric oxide

Nitric oxide (NO) modulates myocardial contractile behavior in several isolated preparations, e.g., cardiac myocytes and papillary muscles, via elevation of intracellular guanosine 3',5'-cyclic monophosphate (cGMP). We have recently reported that the exogenous NO donor, sodium nitroprusside, selectively modulates left ventricular (LV) relaxation in the isolated ejecting guinea pig heart, independent of coronary flow. We now report the effects of endogenously released NO on LV performance in this preparation (constant heart rate and loading). Both bradykinin (1 nM, n = 6) and substance P (100 nM, n = 6) accelerated early LV relaxation (maximum change in time constant, tE, -10.5 +/- 1.6 and -13.4 +/- 2.1%, respectively; both P < 0.05), without significantly altering early systolic parameters (e.g., rate of LV pressure development). These effects were inhibited by hemoglobin (P < 0.05; n > or = 6), which inactivates NO. Bradykinin (100 nM, n = 10) had an additional negative inotropic effect, which was not inhibited by hemoglobin. Neither agonist altered relaxation in isolated papillary muscles. These data suggest that endogenous NO, probably released from coronary microvascular endothelial cells, modulates LV relaxation in the intact heart.

Interactions of Ro15-4513, Ro15-1788 (flumazenil) and ethanol on measures of exploration and locomotion in rats

The present study investigated the role of the GABAA-benzodiazepine (BDZ) receptor complex in mediating ethanol (ETOH)-induced increases in exploration (head-dipping) and locomotion of rats in a holeboard test. Male Sprague-Dawley rats were selected based on low basal exploratory rates to increase the likelihood that ETOH would increase these behaviors. The effects of the BDZ partial inverse agonist, Ro15-4513 (2.5 mg/kg), and the BDZ receptor antagonist, Ro15-1788 (flumazenil) (8.0 mg/kg), alone, and in combination with ETOH (0.25, 0.50 and 0.75 g/kg, IP) were investigated. The 0.25 and 0.50 g/kg doses of ETOH markedly increased both exploration and locomotion in low exploratory rats. The ETOH-induced increases were prevented by Ro15-4513 on both measures at a dose that produced no observable intrinsic action; however, this apparent lack of intrinsic activity on exploration may have been related to the low basal rates of responding in the subjects. The BDZ antagonist, flumazenil, completely reversed the antagonistic action produced by Ro15-4513 of the ETOH-induced stimulant effects on locomotion, however, flumazenil exerted only a marginal statistically significant effect on Ro15-4513's actions on head-dipping. When flumazenil was given alone, it increased head-dipping, but was without effect on locomotion. Flumazenil did not affect ETOH-induced increases in locomotion; however, ETOH and flumazenil appeared to show agonistic effects on exploration. The different effects exerted by flumazenil alone, and in combination with ETOH on head-dipping and locomotion suggest that the actions of flumazenil on these behaviors are mediated through separate mechanisms. The research further suggests that both the anxiolytic and locomotor activational effects of ETOH are mediated through the GABAA-BDZ receptor complex.

Modulation of myocardial relaxation by basal release of endothelin from endocardial endothelium

OBJECTIVE

The aim was to study the potential role of basal endothelin-1 release from endocardial endothelium in isolated ferret papillary muscle preparations.

METHODS

The following interventions were studied: (1) no treatment (time control); (2) endothelin-1 (5 nM); (3) endothelin-1 (5 nM) in the presence of the specific ETA receptor antagonist, BQ123 (10 microM); (4) BQ123 (10 microM) in endocardium-intact muscles; and (5) BQ123 (10 microM) in endocardium-denuded muscles (n = 6 in each group).

RESULTS

Untreated muscles remained stable throughout the experiment. BQ123 fully inhibited the positive inotropic effect of exogenous endothelin-1. In endocardium-intact preparations (n = 6), exposure to BQ123 induced a progressively earlier onset and time course of isometric twitch relaxation [time to peak tension -12.3(SEM 1.8)%, relaxation half time -13.3(1.1)%; both p < 0.01], but had no effect on peak tension or on rate of tension development. Selective denudation of endocardial endothelium induced similar relaxant effects, but also significantly reduced peak tension. In endocardial endothelium-denuded preparations (n = 6), addition of BQ123 did not result in further contractile changes.

CONCLUSIONS

Endocardial endothelium in situ on papillary muscle preparations tonically releases endothelin, resulting in a significantly delayed onset of isometric twitch relaxation. There is no evidence for basal endothelin-1 release from microvascular endothelial cells in this superfused preparation. A similar release of endothelin-1 from endocardial endothelium in the intact heart could influence myocardial contractile behaviour independently of changes in coronary perfusion. Endothelin-1 may have a physiological role in modulating myocardial relaxation.

Localization of Sed5, a putative vesicle targeting molecule, to the cis-Golgi network involves both its transmembrane and cytoplasmic domains

The yeast Sed5 protein, which is required for vesicular transport between ER and Golgi complex, is a membrane protein of the syntaxin family. These proteins are thought to provide the specific targets that are recognized by transport vesicles. We have investigated the mechanism by which Sed5 protein is itself localized. Expression of epitope-tagged versions of the yeast, Drosophila and rat Sed5 homologues in COS cells results in a perinuclear distribution; immuno-EM reveals that the majority of the protein is in a tubulo-vesicular compartment on the cis side of the Golgi apparatus. A similar distribution was obtained with a chimeric molecule consisting of a plasma membrane syntaxin with the Drosophila Sed5 transmembrane domain. This indicates that the membrane-spanning domain contains targeting information, as is the case with resident Golgi enzymes. However, alterations to the transmembrane domain of Drosophila Sed5 itself did not result in its mistargeting, implying that an additional targeting mechanism exists which involves only the cytoplasmic part of the protein. This was confirmed by modifying the transmembrane domain of the yeast Sed5 protein: substitution with the corresponding region from the Sso1 protein (a plasma membrane syntaxin homologue) did not affect yeast Sed5 function in vivo.

The effect of two types of teacher training on implementation of Smart Choices: a tobacco prevention curriculum

This study examined the implementation phase of a four-year research project to test the effectiveness of strategies to increase diffusion of Smart Choices, a school-based tobacco prevention program. The impact on curriculum implementation of two approaches to teacher training are compared. School districts were randomly assigned to a live workshop training or video training condition. The outcome of the evaluation was teachers' implementation of Smart Choices. Results show a lower proportion of video-trained teachers implemented the curriculum, but overall completeness and fidelity of implementation for those teachers who did teach the curriculum were comparable for the two groups. Video-trained teachers, however, were less likely to use brainstorming and student presentations/role plays, two of the methods prescribed by the curriculum. Implications of the results for teacher training are discussed.