Chemically enhanced primary treatment, microsieving, direct membrane filtration and GAC filtration of municipal wastewater: a pilot-scale study

Chemically enhanced primary treatment (CEPT) followed by microsieving and direct membrane filtration (DMF) as ultrafiltration, was evaluated on pilot scale at a municipal wastewater treatment plant. In addition, a granular activated carbon (GAC) filter downstream of DMF was evaluated for the removal of organic micropollutants. Up to 80% of the total organic carbon (TOC) and 96% of the total phosphorus were removed by CEPT with microsieving. The additional contribution of subsequent DMF was minor, and only five days of downstream GAC filtration was possible due to fouling of the membrane. Of the 21 organic micropollutants analysed, all were removed (≥ 98%) by the GAC filter until 440 bed volumes, while CEPT with microsieving and DMF removed only a few compounds. Measurements of the oxygen uptake rate indicated that the required aeration for supplementary biological treatment downstream of CEPT with microsieving, both with and without subsequent DMF, was 20-25% of that in the influent wastewater. This study demonstrated the potential of using compact physicochemical processes to treat municipal wastewater, including the removal of organic micropollutants.

Promoting the degradation of organic micropollutants in tertiary moving bed biofilm reactors by controlling growth and redox conditions

A novel process configuration was designed to increase biofilm growth in tertiary moving bed biofilm reactors (MBBRs) by providing additional substrate from primary treated wastewater in a sidestream reactor under different redox conditions in order to improve micropollutant removal in MBBRs with low substrate availability. This novel recirculating MBBR was operated on pilot scale for 13 months, and a systematic increase was seen in the biomass concentration and the micropollutant degradation rates, compared to a tertiary MBBR without additional substrate. The degradation rates per unit carrier surface area increased in the order of ten times, and for certain micropollutants, such as atenolol, metoprolol, trimethoprim and roxithromycin, the degradation rates increased 20-60 times. Aerobic conditions were critical for maintaining high micropollutant degradation rates. With innovative MBBR configurations it may be possible to improve the biological degradation of organic micropollutants in wastewater. It is suggested that degradation rates be normalized to the carrier surface area, in favor of the biomass concentration, as this reflects the diffusion limitations of oxygen, and will facilitate the comparison of different biofilm systems.

Influence of operational conditions and wastewater properties on the removal of organic micropollutants through ozonation

The objective of this study was to evaluate the influence of operational conditions and wastewater properties on the removal of pharmaceuticals, contrast media and antibiotics through ozonation, in order to facilitate the optimization of treatment and its implementation on a full scale. Pilot-scale ozone oxidation trials were performed on treated wastewater, before and after post-precipitation, over a seven-month period, including summer and winter months. Hydraulic retention times as short as 7 min were found to be sufficient for organic micropollutant removal. A short hydraulic retention time reduces both investment costs and land use. Neither the choice of ozone dispersion method, a static mixer or a Venturi injector, nor the wastewater temperature had any significant effect on the removal efficiency of organic micropollutants, however, higher removal was achieved after on-site post-precipitation with aluminum chloride.

MBBRs as post-treatment to ozonation: Degradation of transformation products and ozone-resistant micropollutants

The degradation potential of micropollutants and transformation products in biological post-treatment after ozonation is partly unknown. A pilot plant with ozonation and subsequent biological treatment in a moving bed biofilm reactor (MBBR) was thus operated over 16 months to investigate the removal of micropollutants and the formation and removal of N-oxide transformation products. Lab-scale kinetic experiments were performed in parallel. At a moderate ozone dose of 0.5 g O₃ g^-1 DOC, further degradation of gabapentin and 3 iodinated contrast media (iomeprol, iopamidol, and iohexol) could be induced by the biofilm at prolonged exposure times. To facilitate comparison of feeding regimens in biofilm systems a new surface-related degradation rate constant was introduced. The availability of substrates in the pilot MBBR influenced the micropollutant degradation kinetics with increasing and decreasing degradation rates. N-oxides from erythromycin, clarithromycin, tramadol, and venlafaxine were formed during ozonation and could not be degraded by the biofilm.

Is dissolved COD a suitable design parameter for ozone oxidation of organic micropollutants in wastewater?

Ozone oxidation of organic micropollutants in biologically treated wastewater was investigated in pilot-scale after a high- and a low loaded activated sludge process. Higher ozone doses were required to remove organic micropollutants in the effluent wastewater from the high loaded activated sludge process. Further comparison of the micropollutant removal was based on normalized ozone doses, expressed as g O₃/g DOC and g O₃/g soluble COD (sCOD). A clear difference was noted for the two effluents when the micropollutant removal was normalized by DOC. This difference disappeared almost completely when the removal was linked to ozone doses normalized by sCOD. The dose-response curves for the organic micropollutants were practically linear in the removal range up to 95%. A linear prediction model was developed and compared with literature values to test the transferability of the obtained results. Results from this comparison indicated that the slope of the dose-response functions could be used to predict the removal efficiency of organic micropollutants at a third plant with an average uncertainty of 10%. The modeled ozone requirements were then set in relation to the COD concentrations in the discharged water from approximately 90 Swedish activated sludge treatment plants with and without nitrogen removal. This comparison highlighted the need for a well-functioning biological treatment for an effective ozone oxidation of organic micropollutants. The results in this study suggest that soluble COD should be further explored for design and modeling of ozone oxidation of organic micropollutants in biologically treated wastewater.

Laboratory-scale assessment of vacuum-degassed activated sludge for improved settling properties

Vacuum degassing of activated sludge was tested at eight different Swedish wastewater treatment plants with laboratory-scale equipment in batch mode in order to evaluate its efficiency on improvement of sludge compaction and settling properties. The results show that the efficiency of the degassing technique is mainly dependent on the initial sludge volume index (SVI) of the target sludge which was found to be related to its process configuration. Facilities with full activated sludge-based nitrogen removal processes, including both nitrification and denitrification, had high SVIs (>300 mL g^-1) and were strongly affected by vacuum degassing with reduction of SVI up to 30%. Nitrogen removal facilities also including biological phosphorus removal showed better compaction and settling properties with relatively lower SVIs and were affected to a lesser extent by degassing with SVI reduction of 10-20%. Wastewater treatment plants without full biological nitrogen removal, lacking either nitrification or denitrification (or both) processes in the activated sludge had the lowest SVIs observed with almost no effect of vacuum degassing.

Investigation of different cell types and gel carriers for cell-based intervertebral disc therapy, in vitro and in vivo studies

Biological treatment options for the repair of intervertebral disc damage have been suggested for patients with chronic low back pain. The aim of this study was to investigate possible cell types and gel carriers for use in the regenerative treatment of degenerative intervertebral discs (IVD). In vitro: human mesenchymal cells (hMSCs), IVD cells (hDCs), and chondrocytes (hCs) were cultivated in three gel types: hyaluronan gel (Durolane®), hydrogel (Puramatrix®), and tissue-glue gel (TISSEEL®) in chondrogenic differentiation media for 9 days. Cell proliferation and proteoglycan accumulation were evaluated with microscopy and histology. In vivo: hMSCs or hCs and hyaluronan gel were co-injected into injured IVDs of six minipigs. Animals were sacrificed at 3 or 6 months. Transplanted cells were traced with anti-human antibodies. IVD appearance was visualized by MRI, immunohistochemistry, and histology. Hyaluronan gel induced the highest cell proliferation in vitro for all cell types. Xenotransplanted hMSCs and hCs survived in porcine IVDs for 6 months and produced collagen II in all six animals. Six months after transplantation of cell/gel, pronounced endplate changes indicating severe IVD degeneration were observed at MRI in 1/3 hC/gel, 1/3 hMSCs/gel and 1/3 gel only injected IVDs at MRI and 1/3 hMSC/gel, 3/3 hC/gel, 2/3 gel and 1/3 injured IVDs showed positive staining for bone mineralization. In 1 of 3 discs receiving hC/gel, in 1 of 3 receiving hMSCs/gel, and in 1 of 3 discs receiving gel alone. Injected IVDs on MRI results in 1 of 3 hMSC/gel, in 3 of 3 hC/gel, in 2 of 3 gel, and in 1 of 3 injured IVDs animals showed positive staining for bone mineralization. The investigated hyaluronan gel carrier is not suitable for use in cell therapy of injured/degenerated IVDs. The high cell proliferation observed in vitro in the hyaluronan could have been a negative factor in vivo, since most cell/gel transplanted IVDs showed degenerative changes at MRI and positive bone mineralization staining. However, this xenotransplantation model is valuable for evaluating possible cell therapy strategies for human degenerated IVDs.

Work status, work hours and health in women with and without children

OBJECTIVES

The authors studied self-reported health in women with and without children in relation to their work status (employed, student, job seeker or homemaker), work hours and having an employed partner.

METHODS

The study group comprised of 6515 women born in 1960-1979 who were interviewed in one of the Swedish Surveys of Living Conditions in 1994-2003. Self-rated health, fatigue and symptoms of anxiety were analysed.

RESULTS

Having children increased the odds of poor self-rated health and fatigue in employed women, female students and job seekers. The presence of a working partner marginally buffered the effects. In dual-earner couples, mothers reported anxiety symptoms less often than women without children. Few women were homemakers (5.8%). The odds of poor self-rated health and fatigue increased with increasing number of children in employed women, and in women working 40 h or more. Poor self-rated health was also associated with the number of children in students. Many mothers wished to reduce their working hours, suggesting time stress was a factor in their impaired health. The associations between having children and health symptoms were not exclusively attributed to having young children.

CONCLUSIONS

Having children may contribute to fatigue and poor self-rated health particularly in women working 40 h or more per week. Student mothers and job seeking mothers were also at increased risk of poor self-rated health. The results should be noted by Swedish policy-makers. Also countries aiming for economic and gender equality should consider factors that may facilitate successful merging of work and family life.

Human disk cells from degenerated disks and mesenchymal stem cells in co-culture result in increased matrix production

Transplantation of mesenchymal stem cells (MSCs) has been suggested for disk degeneration, which is characterized by dysfunctional cells and low proteoglycan production. The aim of this study was to examine the effects of a 3D co-culture system using human disk cells (DCs) and MSCs on collagen and proteoglycan production. DCs and MSCs were expanded in monolayer and grown in pellet cultures for 7, 14 and 28 days and analyzed for hydroxyproline (HP), reflecting total collagen production, and glycosaminoglycan (GAG) accumulation. DCs and MSCs co-cultured at different ratios (25/75, 50/50 and 75%/25%) were examined for GAG accumulation. Collagen type II expression was analyzed immunohistochemically. In a second series, conditioned media were added to pellet cultures of degenerated DCs or MSCs. DCs from degenerated disks and MSCs demonstrated lower total collagen production than non-degenerated DC pellets. GAG production was comparable in DCs and MSCs, except in the youngest donor, with MSC producing about 10 times higher GAG/DNA. Co-cultures resulted in approximately 1.5 times higher GAG/DNA production than DCs. Increased collagen type II expression was seen in co-cultures compared to DC or MSC culture alone, except in the case with highly active MSCs. No positive effect of conditioned media was seen. In conclusion, co-culture of MSCs with degenerated DCs increased proteoglycan and collagen-type ceII production, indicating that in future clinical therapy MSCs can be transplanted without pre-differentiation in vitro. The lack of effect of conditioned media suggests that the positive effect of co-culture on matrix production is not due to soluble factors.

Clinical course and symptomatology of angina pectoris in a population study

The clinical course of angina pectoris was studied in a follow-up study of 427 patients with angina from a general population sample. The subjects were men aged 56-65 years at the time of follow-up. After a mean follow-up time of 5.8 years, 55% were still suffering from angina pectoris, 15% had died and a further 19% were either free from chest pain or had chest pain considered to be of different origin. In the group with definite angina pectoris at follow-up (n = 236), 29% had sustained a myocardial infarction, 23% had symptoms of intermittent claudication, 36% were treated for hypertension and 15% had diabetes. Many of the angina patients suffered from other chest conditions in addition to anginal symptoms. Most of the patients (56%) had infrequent attacks (a few times per month or less often) and were not severely incapacitated by their symptoms. Only one fifth worked full time compared with more than half of those in the same age groups in the general population. Only 16 of those interviewed had undergone bypass surgery and a further 16 had disabling angina but, for various reasons, they had not been operated on. The implications are that most angina patients do well on pharmacological treatment alone even though they are limited socially as well as physically. Precipitating factors other than physical activity were also investigated and associations were found between susceptibility to cold, early morning angina, angina at rest and attacks of long duration, possibly indicating a mechanism of vasospasm superimposed on a fixed stenosis.

Prevalence of angina pectoris and myocardial infarction in a general population sample of Swedish men

A primary preventive trial against cardiovascular diseases has been in progress since 1970 in Göteborg, Sweden. The study population comprises all men in the city born in 1915-22 and 1924-25, a total of about 30 000 men. One third of this population constitutes the intervention group. The prevalence of angina pectoris and myocardial infarction among men aged 47-53 years has been studied in this group. The cases were identified by means of a postal questionnaire, direct interview at screening examination and by clinical examination. A validation of the postal questionnaire technique gave a sensitivity of 74% and a specificity of 94%. The minimum prevalence of angina pectoris amounted to 4.3% and the prevalence of myocardial infarction to 1.6%. In the angina series, 22% had suffered a myocardial infarction that preceded angina pectoris in 9%.

Relation between ST-depression and chest pain in patients with coronary heart disease receiving no treatment and after beta-blockade and combined alpha-beta-blockade

The bicycle exercise tolerance was studied in ten patients with angina pectoris after one week's treatment with an alpha-beta-blocker (labetalol 300 mg b.d.), alpha-beta-blocker (propranolol 80 mg b.d.) and placebo. The ST-segment of the ECG was continuously evaluated by on-line computerized averaging of complexes which greatly reduces noise and eliminate artefacts caused by varying baseline. Blood pressure was lowest with labetalol and heart rate lowest with labetalol and of heart rate during exercise was equally well depressed by both drugs. They also attenuated ST-depression at a given load but enhanced ST-depression for a given heart rate. At heart rate 100/min ST-depression was significantly greater with propranolol than with labetalol. It is concluded that provided ST-depression during treatment with B-blockers is correlated to myocardial ischemia in the same way as without such treatments used, other factors, e.g. an increase in cardiac size, will contribute more to the ischemia. labetalol may cause less increase in cardiac size than propranolol.

Relationship between dyspnea and chest pain ischemic heart disease

Dyspnea may form a differential diagnostic symptom to chest pain in ischemic heart disease (IHD) but may also precede angina pectoris (AP) as a manifestation of IHD. In the Primary Preventive Trial in Göteborg the occurrence of AP and its relation to dyspnea has been studied in a random population sample of men aged 47-54 years at entry to the study and followed for 4 years. In the corss-sectional study dyspnea was reported in 21% of the total population and in 70% of the angina population. Dyspnea at entry to the study was reported in 36% among cases who developed AP along during the follow-up time and in 35% among cases who developed AP associated with myocardial infarction. The dyspnea was not related to smoking habits or to low grade of physical activity. The report of dyspnea before chest pain in IHD may be due to misinterpretation in early cases. On the other hand it is also known that intermittent left ventricular failure coincident with attacks of myocardial ischemia will give a subjective feeling of dyspnea. According to our study there is a definite association between AP and dyspnea. In some cases dyspnea precedes AP whereas in others the chest pain precedes the dyspnea. The symptom dyspnea also carries important prognostic information in IHD.

"Nonspecific" chest pain associated with high long-term mortality: results from the primary prevention study in Göteborg, Sweden

BACKGROUND

The syndrome angina pectoris with effort-related chest pain or discomfort is usually easy to recognize. However, vague and nonspecific symptoms may cause little reason for extensive evaluation. The prognosis of such patients in the general population has so far not been well described.

HYPOTHESIS

The study was undertaken to investigate long-term prognosis in men with chest pain considered to be nonspecific in comparison with men with typical angina pectoris (AP) or prior myocardial infarction (MI), and men without chest pain.

METHODS

At the second screening of the Göteborg Primary Prevention Study in 1974-1977, 6,488 men aged 51 to 59 years at baseline were available for the present analysis. Men who had responded positively to a postal questionnaire about chest pain during exercise or at rest were interviewed by a physician according to a Rose questionnaire at the screening examination. Those with typical or probable AP were further examined by single experienced physician. The following four groups were formed: Group 1: men who did not complain of chest pain (n = 5,545). Group 2: men who had not consulted any doctor because of chest pain, but who had chest pain according to a questionnaire (n = 441); these men were not considered to have AP according to a three-step examination by experienced physicians. Group 3: typical AP (n = 232). Group 4: men who had suffered an MI (n = 134).

RESULTS

During 16 years of follow-up, coronary heart disease (CHD) mortality for Groups 1-4 was 8.0, 19.5, 24.8, and 48.5%, respectively. Mortality from all cardiovascular diseases was 11.5, 24.5, 31.2, and 59.0%, respectively. Noncardiovascular disease mortality was 14.1, 17.7, 14.3, and 8.7%, respectively. Thus, the relative risk (RR) for CHD mortality among men with nonspecific chest pain (Group 2) was 2.77 [95% confidence interval (CI) 2.20, 3.50], for all cardiovascular disease mortality 2.46 (95% CI 2.00, 3.02), and for noncardiovascular disease mortality 1.60 (95% CI 1.28, 2.00). Total mortality in this group was as high (44%) as among those with typical AP (45%), but the highest mortality was found among men with a previous MI (68%). In men without chest pain it was 26%. Patients of Groups 2-4 had higher levels of cardiovascular risk factors than those in Group 1. Neither any specific questions in the Rose questionnaire, nor electrocardiographic changes at rest (uncommon) were of prognostic significance. Serum cholesterol, systolic blood pressure, diabetes, and smoking were significant predictors of outcome, both with respect to fatal CHD and to total mortality during the 16-year follow-up.

CONCLUSION

We found a high cardiovascular as well as noncardiovascular mortality among patients with chest pain who had not been considered to have AP at a three-step examination procedure. It is important to be suspicious of early CHD symptoms in men (and women?) with "nonspecific" chest symptoms and to analyze their cardiovascular risk factor pattern further because they are at considerably higher risk for future events than those in whom CHD is not suspected.

Advanced oxidation of refractory organics in leachate--potential methods and evaluation of biodegradability of the remaining substrate

An assessment of potential methods suitable for degradation and/or reduction of refractory organics was performed on landfill leachate from SYSAV AB, Malmö, Sweden. Pretreatment of the leachate was performed in a sequence batch reactor designed for nitrification in activated sludge. Oxidation of the leachate was then O3, O3/pH adjustment (pH 9 and 10), H2O2, O3/H2O2 and performic acid in lab-scale reactors. The degradation of organic material was followed with chemical oxygen demand (COD) measurements for all experiments except for the performic acid treatment for which total organic carbon (TOC) measurements were used. The potential degradation of refractory organics into biodegradable organic material was analysed by subsequent oxygen uptake rate (OUR) measurements in laboratory batch reactors. Ozonation of biologically pre-treated leachate increased reduction of the organic material. The most biodegradable organic material was produced after oxidation with only ozone and ozonation at pH 9. Performic acid did not reduce the content of organic material in the leachate. However, a combination of biological pretreatment, chemical oxidation with O3/H2O2 and a subsequent biological process resulted in the most efficient oxidation method for the tested leachate.

Mixed carbon sources for nitrate reduction in activated sludge-identification of bacteria and process activity studies

Mixtures of methanol and acetate as carbon source were investigated in order to determine their capacity to enhance denitrification and for analysis of the microbial composition and carbon degradation activity in activated sludge from wastewater treatment plants. Laboratory batch reactors at 20 degrees C were used for nitrate uptake rate (NUR) measurements in order to investigate the anoxic activity, while single and mixed carbon substrates were added to activated sludge. Microautoradiography (MAR) in combination with fluorescence in situ hybridisation (FISH) were applied for microbial analysis during exposure to different carbon sources. The NUR increased with additions of a mixture of acetate and methanol compared with additions of a single carbon source. MAR-FISH measurements demonstrated that the probe-defined group of Azoarcus was the main group of bacteria utilising acetate and the only active group utilising methanol under anoxic conditions. The present study indicated an improved denitrification potential by additions of a mixed carbon source compared with commonly used single-carbon additions. It is also established that Azoarcus bacteria are involved in the degradation of both acetate and methanol in the anoxic activated sludge.

Oxygen uptake rate measurements for evaluation of ozonation of municipal wastewater

Ozonation has become more frequently used as oxidant to reduce chemical oxygen demand (COD) and toxic substances in wastewater originating from different industrial processes. An ozonation pilot plant followed by two parallel biological filters are used to investigate the possibility to reduce the high concentration of refractory COD in the effluent from a municipal wastewater treatment plant, partly loaded with biologically treated wastewater from a large pharmaceutical industry. COD measurements are used to evaluate the overall reduction of organic matter, oxygen uptake rate (OUR) and volatile fatty acids measurements are used for evaluation of the biodegradability of the remaining COD after ozonation. The impact of the ozone dose on the overall COD degradation and degradability of the remaining COD has been estimated. Biochemical oxygen demand (BOD) measurements confirm that parts of the COD are converted into biodegradable organic matter by ozonation. Biofilters following the ozonation plant secure that any degradable organic matter produced by ozonation is removed, which is confirmed from OUR-measurements.

Biological detoxification of tar-water

Gasification is an important option for the swift implementation of biomass combined heat and power processes in the Danish energy supply system. Tar-water produced by the gas-cleaning system of gasifiers may contain substances toxic to nitrifying bacteria. As the gasification plants are small and often located in the catchment area of small wastewater treatment plants, discharge of the tar-water may be critical for wastewater treatment plants operated with nitrogen removal. Tar-water from a full-scale updraft gasifier has been thoroughly examined with respect to inhibition of nitrification and the toxicity for nitrifying bacteria has been evaluated for the dominating constituents in the tar-water. Simple organic substances make up the dominating part of the organic matter but phenol and phenolic compounds are also present in significant concentrations. The identified substances are biologically degradable and it has been demonstrated that most of the organic matter together with the toxicity can be eliminated in an aerobic activated sludge process.

Age and angina as predictors of quality of life after myocardial infarction: a prospective comparative study

OBJECTIVES

The objectives were to compare quality of life (QoL) after first myocardial infarction with an age- and sex-adjusted normative population and to test whether the 1-month QoL had predictive properties.

DESIGN

QoL was assessed by self-administered questionnaires (SF-36 and Cardiac Health Profile) 1, 3 and 6 months after index-event. Participants were 60 consecutive patients (20% women) with a mean age of 58 +/- 7.4 years.

RESULTS

Patients > or =59 years improved in Physical (PCS) and Mental Component Summary (MCS), scoring comparable to community norms at 6 months. However, patients <59 years improved in PCS but not in MCS. and scored significantly below community norms in both PCS (x = 44.7, CI 40.6-48.7 vs x = 50.3, CI 49.3-51.4) and MCS (x = 45.9, Cl 41.8-49.9 vs. x = 51.3, CI 50.3-52.4) at 6 months. Predictors for MCS were age (p = 0.025) and Vitality (p = 0.020) both positively related to QoL. Predictors for PCS were Physical Function (p = 0.003) and CCS score (p < 0.001) where angina grade was negatively related to QoL.

CONCLUSION

Because of impaired mental recovery in younger post-infarction patients, their need of special attention in the rehabilitation process must not be overlooked.

Effects on the nervous system in different groups of workers exposed to aluminium

OBJECTIVE

To investigate possible neurotoxic effects in groups of aluminium pot room and foundry workers, aluminium welders, and a small group of workers exposed to aluminium in the production of flake powder.

METHODS

Exposure to aluminium was evaluated with aluminium concentrations in blood and urine as well as a questionnaire. The groups exposed to aluminium were compared with a group of mild steel welders. Neurotoxic effects were studied with mood and symptom questionnaires and several psychological and neurophysiological tests.

RESULTS

The pot room and foundry workers showed very low aluminium uptake as their aluminium concentrations in blood and urine were close to normal, and no effects on the nervous system were detected. The group of workers exposed to flake powder had high concentrations of aluminium in blood and urine, even higher than those of the aluminium welders. However, aluminium could not be shown to affect the functioning of the nervous system in flake powder producers. Although significant effects could not be shown in the present analysis of the data on welders, the performance of the welders exposed to high concentrations of aluminium was affected according to the analyses in the original paper from this group.

CONCLUSIONS

For the pot room and foundry workers no effects related to the exposure to aluminium could be found. For the group of flake powder producers exposed for a short term no effects on the nervous systems were evident despite high levels of exposure. Due to the high concentrations of aluminium in the biological samples of this group, measures to reduce the exposure to aluminium are recommended, as effects on the central nervous system might develop after protracted exposures. However, this assumption needs to be verified in further studies.

[Prognosis is often poor in chest pain not interpreted as angina pectoris. Simultaneous occurrence of cardiovascular risk factors increases the risk of premature death]

BACKGROUND

Typical angina pectoris is easy to recognize, but coronary insufficiency may present with nonspecific chest discomfort.

AIMS OF STUDY

We wanted to investigate long-term prognosis in men with different types of chest pain.

METHODS

A random population sample comprising 5,773 men aged 51-57 years at baseline were followed for 16 years.

RESULTS

Mortality due to coronary heart disease was 8.0% among men without chest pain, 19.5% (total mortality 44%) among those with non-specific chest pain, 24.8% (total mortality 45%) among those with typical angina and 48.5% among those with a history of myocardial infarction at baseline.

CONCLUSION

Non-specific chest pain is associated with poor prognosis, and coronary risk factors have strong predictive value.

Subchronic toluene exposure in low concentrations produces signs of reduced dysfunction in the 6-hydroxydopamine lesioned nigrostriatal dopaminergic system of the rat

The effect of a subchronic (4-week) exposure to low concentrations of toluene (40 or 80 parts per million, ppm) on the brain dopaminergic system has been examined in a rat model of Parkinson's disease. A unilateral lesion of the substantia nigra (SN) dopamine (DA) nerve cells was performed by injection of a low dose of 6-hydroxydopamine (6-OH DA). The peak activity of contralateral rotational behavior induced by apomorphine was significantly decreased after exposure to 80 ppm toluene. Analysis of the neostriatum and SN ipsilateral to the lesion revealed that toluene (80 ppm, but not 40 ppm) counteracted the 6-OH DA-induced reductions of DA tissue levels both within the SN and the neostriatum. Also the lesion-induced reduction of immunoreactivity for tyrosine hydroxylase (TH IR) in the neostriatum was partly counteracted by the toluene exposure (80 ppm). In conclusion, a subchronic exposure to low doses of toluene (80 ppm) leads to signs of reduced dysfunction of the nigrostriatal dopaminergic system after the neurotoxic treatment.

Natural history of myocardial infarction and angina pectoris in a general population sample of middle-aged men: a 16-year follow-up of the Primary Prevention Study, Göteborg, Sweden

OBJECTIVES

Although many studies have described prognosis in patients with coronary heart disease (CHD), few have compared outcome in men with clinical evidence of CHD with healthy men from the general population over an extended follow-up. This study aimed to compare long-term prognosis in men with a history of myocardial infarction (MI) and in men with angina pectoris (AP) without MI, with men without clinical signs of CHD.

DESIGN

Longitudinal general population study.

SETTING

City of Göteborg, Sweden.

SUBJECTS

From a general population sample, 195 men who had survived an MI for 0-19 years (median 3 years) and 314 men with AP but no MI (uncomplicated AP) at baseline in 1974-77 were identified and compared with 6591 men without clinical coronary disease. All were aged 51-59 years. Incident non-fatal and fatal cases occurring until the beginning of 1983 were also followed (n = 317).

MAIN OUTCOME MEASURES

Death from CHD, from other causes and from all causes during a follow-up of at least 16 years.

RESULTS

Overall survival was 72% amongst men without coronary disease, 53% amongst men with uncomplicated AP and 34% amongst men with past MI at baseline. In survivors of MI the risk-factor-adjusted relative risk (RR) of coronary death during follow-up was 6.67 (95% confidence interval (CI) 5.29-8.39), of dying from non-cardiovascular causes 1.35 (0.96-1.91), and of dying from any cause 3.20 (2.67-3.83). During the first 4 years after the baseline examination, the adjusted RR of CHD death was 15.96 (10. 29-24.74), and of dying from any cause 5.22 (3.68-7.41). During the last 4 years of follow-up, relative risk was still 5.87 (3.44-10.01) for CHD death and 2.93 (2.05-4.18) for death from any cause. In men with uncomplicated AP, the adjusted relative risk of CHD death during the first 4 years was 4.05 (2.27-7.22) and 3.23 (2.10-4.96) during the last 4-year period. After the first year, the incident MI cases had the same average annual mortality (about 5%) as the prevalent cases.

CONCLUSIONS

In survivors of MI, mortality risk remained high even after an extended follow-up. Men with angina had a better prognosis, but still a compromised survival compared with the general population.

Echocardiography allows early detection and long-term survival after infarct free wall rupture

Approximately one third of free wall infarct ruptures are subacute and theoretically accessible for surgery. Two-dimensional echocardiography is an important tool in the early diagnosis of cardiac rupture. We report the successful treatment of a 74-year-old woman with subacute free wall rupture, who is still alive 3 years after surgery.

Mutagenicity from neutrophils after challenge with Helicobacter pylori and bile

OBJECTIVE

To study some mechanisms involved in Helicobacter pylori (H. pylori)-induced gastric carcinogenesis.

DESIGN

In vitro study.

SETTING

Medical centre hospital, Sweden.

INTERVENTIONS

Mutagenicity in Ames' test of neutrophils challenged for 2 hours or more by two different strains of H. pylori. One strain designated NCTC 11637 by the National College of Type Cultures activated neutrophils to an oxidative burst and producing vacuolating cytotoxin, the other strain C-7050 lacked these abilities. Mutagenicity was also studied with sterile human gall bladder bile alone added to neutrophils or in combination with both neutrophils and H. pylori.

RESULTS

There was no increase in the number of revertants with the crude suspension or the supernatant of neutrophils challenged for 1 hour or less with H. pylori, bile, or the combination of both. However, in 5 out of 19 experiments there was significant mutagenicity after challenge of neutrophils for 2 hours or more with either strain of H. pylori, bile, or the combination of the two. The strongest mutagenicity was obtained after challenge over night (18 hours) with the combination of H. pylori and bile.

CONCLUSION

Mutagenicity occurs when neutrophils are challenged with H. pylori and bile. Factors other than reactive oxygen metabolites seem to be responsible.

Serum cholesterol and long-term prognosis in middle-aged men with myocardial infarction and angina pectoris. A 16-year follow-up of the Primary Prevention Study in Göteborg, Sweden

OBJECTIVE

To compare the role of serum cholesterol in the long-term prognosis of men with a history of myocardial infarction, in men with clinical angina without myocardial infarction, and men without clinical coronary disease.

METHODS

In the second screening of the Primary Prevention Study in Göteborg which comprised 7100 men aged 51 to 59 years at baseline in 1974-1977, 314 men with clinical angina but no myocardial infarction at baseline were identified and 195 men who had survived a myocardial infarction for 0 to 19 years (median 3 years).

RESULTS

Of the men without clinical coronary disease at baseline and cholesterol at or below 5.2 mmol.l-1, 2.7 per 1000 observation years died from coronary disease compared to 8.5 per 1000 of the men with serum cholesterol of 7.2 mmol.l-1 or more. Corresponding figures for men with angina was 5.5 and 31.0 per 1000 observation years, and for men with prior myocardial infarction 19.8 and 58.3, respectively, per 1000. After adjustment for age, smoking, systolic blood pressure, body mass index and diabetes the risk of coronary death in men with serum cholesterol above 7.2 mmol.l-1 compared to below 5.2 mmol.l-1 was 2.42 (1.66-3.51) in healthy men, 4.82 (1.44-16.09) in men with angina, 2.70 (0.95-7.67) in survivors of myocardial infarction, and 4.07 (1.86-8.91) in the combined group of men with either angina or prior infarction. The strongest effect was seen during the first half of the follow-up, with an adjusted relative risk for high in relation to low serum cholesterol of 8.08 (1.95-33.55) in men with preexisting coronary disease. Non-coronary deaths varied little by serum cholesterol or coronary disease status at baseline. After 16 years, 76% of the healthy men with low cholesterol and 65% of healthy men with cholesterol above 7.2 mmol.l-1 were still alive. Of the men with prior myocardial infarction, 50% in the group with low cholesterol were alive after 16 years, as compared to 21% of those with high cholesterol.

CONCLUSION

The long-term absolute risk of death in men with coronary disease and elevated serum cholesterol is very high. Implementation of lipid-lowering strategies shown to be efficacious is important in this high-risk group.

Subacute toluene exposure increases DA dysfunction in the 6-OH dopamine lesioned nigrostriatal dopaminergic system of the rat

The potential neurotoxicity of the solvent toluene to the nigrostriatal dopaminergic system was assessed in a rat model of Parkinson's disease. Rats, 1 day after a unilateral injection of 6-hydroxydopamine (6-OH DA) into the substantia nigra, inhaled air or different concentrations of toluene (80, 300 or 1000 ppm), 6 h/day for 3 days. The animals were sacrificed 2 days after the last exposure and biochemical measurements of catecholamines and 3,4-dihydroxyphenylacetic acid (DOPAC) were performed in the neostriatum and substantia nigra. Toluene at 80 and 1000 ppm significantly enhanced the depletion of striatal DOPAC levels induced by the lesion and produced at 80 and 300 ppm a trend for intensifying the 6-OH DA-induced depletion of striatal DA stores. The alterations induced after the combined challenge to the dopaminergic nigrostriatal system may reflect endangering actions of toluene.

Electrocortical responses to ecologically relevant visual stimuli among professional drivers with and without cardiovascular disease

Electrocortical responses were assessed using two simulated aspects of visual signals encountered in traffic: the Glare Pressor Test (GPT) and Event-Related Potential Avoidance Task (ERPAT) among four groups of male professional drivers: 12 with ischemic heart disease (IHD), 12 hypertensives, 10 borderline hypertensives, 34 who were apparently healthy and 23 nonprofessional driver healthy control subjects. The blood pressure (BP) responses immediately after the ERPAT were also measured. There was a significant between groups effect for the amplitude of the target N2 component in the ERPAT (p = 0.02), with the lowest means among the drivers with IHD and the highest among those with hypertension. Drivers with IHD also showed the highest diastolic BP reactivity to the ERPAT. Significantly more than the expected number of drivers with IHD failed to recover alpha activity after the first glare impulse of the GPT. Professional drivers who failed to recover baseline levels of alpha activity after the GPT showed a significantly smaller N2 amplitude compared to those who recovered (p = 0.01). There was a positive correlation between abundance of alpha activity at rest with P300 amplitude (p = 0.02). An inverse relation was found between number of work hours behind the wheel and the amplitude of the target P300 (p = 0.04). Results are interpreted in light of recent advances concerning integrative mechanisms of defence versus vigilance response patterns. The findings in this study justify further applications of these psychophysiologic methods to assess the relationship between simulated signals of the work environment and mechanisms of cardiac risk in this occupational group.

Effects on the nervous system among welders exposed to aluminium and manganese

OBJECTIVES

The purpose was to study the effects on the nervous system in welders exposed to aluminium and manganese.

METHODS

The investigation included questionnaires on symptoms, psychological methods (simple reaction time, finger tapping speed and endurance, digit span, vocabulary, tracking, symbol digit, cylinders, olfactory threshold, Luria-Nebraska motor scale), neurophysiological methods (electroencephalography, event related auditory evoked potential (P-300), brainstem auditory evoked potential, and diadochokinesometry) and assessments of blood and urine concentrations of metals (aluminium, lead, and manganese).

RESULTS

The welders exposed to aluminium (n = 38) reported more symptoms from the central nervous system than the control group (n = 39). They also had a decreased motor function in five tests. The effect was dose related in two of these five tests. The median exposure of aluminium welders was 7065 hours and they had about seven times higher concentrations of aluminium in urine than the controls. The welders exposed to manganese (n = 12) had a decreased motor function in five tests. An increased latency of event related auditory evoked potential was also found in this group. The median manganese exposure was 270 hours. These welders did not have higher concentrations of manganese in blood than the controls.

CONCLUSIONS

The neurotoxic effects found in the groups of welders exposed to aluminium and manganese are probably caused by the aluminium and manganese exposure, respectively. These effects indicate a need for improvements in the work environments of these welders.

Short-term and sustained renal effects of angiotensin II receptor blockade in healthy subjects

We investigated the short-term and sustained hormonal and renal effects of angiotensin II (Ang II) receptor blockade in normotensive healthy volunteers. Twenty-four subjects maintained on a fixed sodium diet were randomized to receive for 8 days a placebo or 10 or 50 mg doses of the Ang II antagonist irbesartan (SR 47436, BMS 186295) according to a double-blind, parallel group design. Plasma renin activity, plasma immunoreactive Ang II and aldosterone levels, blood pressure, renal hemodynamics, and urinary electrolyte excretion were measured for 8 hours after the first and eighth administration of each dose of irbesartan or placebo. Ang II receptor blockade with irbesartan induced a dose-dependent compensatory increase in plasma renin activity and plasma angiotensin levels and a significant decrease in plasma aldosterone levels. The compensatory rise in plasma renin activity and Ang II levels was more pronounced on day 8, reflecting a long duration of the blocking effect of irbesartan. Irbesartan induced small changes in blood pressure and did not significantly modify renal blood flow and glomerular filtration rate. However, a significant decrease in filtration fraction was observed during receptor blockade on days 1 and 8. The tubular effects of irbesartan were characterized by a dose-dependent increase in sodium and chloride excretions. Interestingly, the cumulative natriuretic response to Ang II receptor blockade was similar on days 1 and 8, suggesting that in these subjects, renal Ang II receptors are not blocked over 24 hours during repeated administration even though this antagonist has a long duration of action (t1/2 of 15 to 17 hours).(ABSTRACT TRUNCATED AT 250 WORDS)

Function of the auditory system, the visual system, and peripheral nerve and long-term combined exposure to toluene and ethanol in rats

Male pigmented rats (n = 36) were exposed to toluene and/or ethanol (1000 p.p.m. toluene in the inhaled air 21 hr/day, and 5.7-8.0% ethanol in the drinking water continuously) during 8 weeks. Electrophysiological recordings were made 1 week after the exposure. Auditory sensitivity (auditory brainstem response) was reduced only after exposures including toluene. At 20 kHz, ethanol antagonized toluene-induced loss of auditory sensitivity (P < 0.05). Flash evoked potentials were not affected in any group. In peripheral nerve, exposures containing ethanol were followed by increased amplitudes of nerve and muscle action potentials. Exposures including toluene were followed by an increase in liquid consumption.

Function of the auditory and visual systems, and of peripheral nerve, in rats after long-term combined exposure to n-hexane and methylated benzene derivatives. II. Xylene

Rats were exposed to xylene, to n-hexane, or to xylene together with n-hexane, each solvent 1000 p.p.m. (1000 + 1000 p.p.m. in mixed exposure), 18 hr/day, 7 days/week during 61 days. Neurophysiological recordings were made 2 days, 4 months, and 10 months after the end of exposure. Exposure to n-hexane alone, or xylene alone, caused a slight loss of auditory sensitivity as recorded by auditory brainstem response 2 days after the exposure. Exposure to n-hexane together with xylene caused persistent loss of auditory sensitivity (7-17 dB; P < 0.05) which was non-additively enhanced (P < 0.01). The latencies of the flash evoked potentials in the group exposed to n-hexane alone were prolonged (re C group) 2 days after exposure, while smaller prolongations were found in the group exposed to xylene together with n-hexane. Exposure to n-hexane alone caused a marked decrease in nerve conduction velocity, while simultaneous exposure to xylene inhibited n-hexane-induced velocity reduction in peripheral nerve (P < 0.01).

Function of the auditory and visual systems, and of peripheral nerve, in rats after long-term combined exposure to n-hexane and methylated benzene derivatives. I. Toluene

Rats were exposed to n-hexane, toluene, or toluene together with n-hexane, each solvent 1000 p.p.m. (1000 + 1000 p.p.m. in combined exposure), 21 hr/day, 7 days/week during 28 days. Neurophysiological recordings were made 2 days, 3 months, and one year after end of exposure. A reduction in auditory sensitivity, recorded by click evoked auditory brainstem response, was observed 2 days after exposure to toluene alone, or to toluene together with n-hexane, but not after exposure to n-hexane alone. The reduction lasted one year after the exposure. Three months after combined exposure, a synergistic enhancement of loss of auditory sensitivity was observed in the mixed exposure group. One amplitude in the flash evoked potentials was lowered in the n-hexane exposed group 2 days after exposure. No such reduction was seen after simultaneous exposure to toluene. Exposure to n-hexane alone caused a marked decrease in peripheral nerve conduction velocity 2 days and 3 months after exposure, while exposure to n-hexane together with toluene had only a small effect on this velocity.

Effect of exposure to 2,5-hexanediol in light or darkness on the retina of albino and pigmented rats. II. Electrophysiology

Albino (Sprague-Dawley) and pigmented (Norwegian Brown) male rats were exposed to 2,5-hexanediol (H; 1%) in their drinking water for 5 or 8 weeks, respectively. Half of the rats of each strain were housed in light (average 30 cd/cm2 inside cage, 12 h/day); the other half was kept in constant darkness. Control groups were studied in parallel under identical conditions but without H. Electrophysiological recordings were made 2-5 days and 13 weeks after the end of the exposure to H. Alterations in the visual system, as measured by electroretinography and visual evoked response, were found in groups of albino rats exposed to H and/or light. The pupillary diameter was enlarged in the albino group exposed to both H and light. Among the pigmented rats, alterations were recorded only in the visual evoked response of the H exposed groups. The results demonstrate that simultaneous exposure to H and light can lead to alterations in visual function that are more severe than those induced by each agent alone, and may exceed a simple summation.

Effect of exposure to 2,5-hexanediol in light or darkness on the retina of albino and pigmented rats. I. Morphology

Male albino (Sprague Dawley) and pigmented (Norwegian Brown) rats received 1% 2,5-hexanediol (H) in their drinking water for 5 or 8 weeks, respectively. The rats were housed either in 12 h light (average 30 cd/cm2 inside cage) and 12 h darkness (group LH) or in total darkness (group DH). Two control groups (Light only, LC; Darkness only, DC) were studied in parallel under identical conditions. The animals were sacrificed at the end of H exposure or after an ensuing 13-week period without H but under the same lighting conditions. The retinas of albino rats in the LH group showed a reduction (compared to the LC, DH and DC groups) in the number of nuclei per unit area of the outer nuclear layer (ONL; p < 0.05) and degeneration of the outer segment and the inner segment layers (photoreceptor cells). A less pronounced loss of nuclei was seen in the LC group. No decrease in the number of nuclei, or signs of degeneration, were demonstrated in the albino DH or DC groups. Thirteen weeks after exposure to H, the albino LH rats had lost about 50% of the nuclei in the ONL (p < 0.05) and the outer plexiform layer (OPL) had almost disappeared. At the corresponding time, in the pigmented rats the LH and DH groups differed from the LC and DC groups. The degenerative process resulted in no inflammatory changes in the retina. The results imply an interaction exceeding simple summation after exposure to light and H, in destroying photoreceptors and OPL (p < 0.001) in albino rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Similar effects of ethanol and tert-butanol on amino acid concentrations in rat serum and liver

Both metabolic and nonmetabolic mechanisms have been proposed to the plasma amino acid decreasing effect of an acute ethanol load. We used tert-butanol, an alcohol that is only minimally metabolized, as a tool to explain the mechanism behind the amino acid decreasing effect of ethanol. Acute administration of tert-butanol was found to exert a decreasing effect on rat serum amino acid concentrations similar to that of ethanol, indicating that the mechanism of the amino acid decreasing effect of ethanol is primarily due to ethanol itself and not to its oxidation. Ethanol and tert-butanol also had similar effects on liver amino acid concentrations, including an increase in the glycine concentration and decrease in the concentrations of glutamate, alanine, leucine, and tyrosine.

Neisseria meningitidis in specimens from urogenital sites. Is increased awareness necessary?

Neisseria meningitidis serogroups B type 2 and Y were isolated from urogenital specimens from three heterosexual patients. The first patient was a young man with the clinical signs and microscopic findings of a typical gonococcal urethritis. The second was a middle-aged woman with cervicitis, in whom neither Neisseria gonorrhoeae nor Chlamydia trachomatis were demonstrated by culture. In the third patient, a young woman, N. meningitidis was associated with cervicitis, acute salpingitis, and peritonitis. The patients' clinical symptoms responded quickly to antibiotic treatment. Meningococci of the same serogroup/serotype as the index cases were demonstrated in two of the sexual consorts in pharyngeal specimens but not in genitourinary specimens. Orogenital sexual practice seemed to be the most likely route of transmission. During the period of this study (August 1989-March 1990), the three meningococcal strains observed at the authors' laboratory represented 20% of the total number of urogenital isolates of pathogenic Neisseria. A greater awareness of this problem from medical, diagnostic, epidemiologic, and legal viewpoints is therefore needed.

Development of tolerance to the plasma amino acid-decreasing effect of ethanol in the rat

Male Sprague-Dawley rats were treated for one month with daily intraperitoneal injections of ethanol (2 g kg-1), or saline. After this pretreatment, animals from each group were given acute doses of ethanol (2 g kg-1) or saline. Plasma amino acid concentrations and brain tyrosine, tryptophan, dopamine, 5-HT and 5-HIAA concentrations were measured in samples collected 1 h after the injections. Acute administration of ethanol induced a dramatic fall in the concentrations of 18 out of 20 plasma amino acids in animals pretreated with saline. In animals chronically pretreated with ethanol this decrease was much smaller. Furthermore, the decrease was significantly lower for 6 of the measured amino acids in the chronic ethanol group compared with the saline-treated control group. Tolerance to the plasma amino acid decreasing effect of ethanol had thus developed. This acquired tolerance might be explained by both pharmacokinetic and pharmacodynamic mechanisms. Chronic administration of ethanol induced increased concentrations of tyrosine and dopamine in the brain, probably due to increased transport of tyrosine into the brain caused by an increase in the ratio of tyrosine to large neutral amino acids in plasma.

Manganese exposure in steel smelters a health hazard to the nervous system

In a study of the effects of low-level exposure to manganese (0.19-1.39 mg/m3 for 1-45 years) 30 men (aged 20-64 years) from two steel smelting works and 60 unexposed referents (aged 22-65 years) were examined with the use of a general health inquiry, electroencephalography, event-related auditory evoked potentials, brain-stem auditory evoked potentials, diadochokinesometry, simple and complex reaction time, finger tapping, digit span, mental arithmetic, vocabulary, a coding task, manual dexterity, symptoms, and mood scales, the diagnostic interview scheme, a dynamic rating scale for neurasthenic syndrome, and a comprehensive psychopathological rating scale. No group differences were found in the electroencephalography or the psychiatric examinations. However, there were increased frequencies of some symptoms, the diadochokinesis was slower, the P-300 latency and reaction time were increased, and finger-tapping and digit-span performance were impaired in the exposed group. These effects were interpreted as early (subclinical) signs of disturbances of the same type as parkinsonism.

Dose-dependent decrease in rat plasma amino acids after acute administration of ethanol

Male rats were given three different doses of ethanol in i.p. injections (0.66, 1.33 and 2.00 g kg-1). A dose-dependent decrease in the concentrations of most plasma amino acids was observed. For the total amino acid concentration this decrease was 5, 16 and 22%, respectively, compared with a saline-treated control group. It has previously been suggested that the oxidation of ethanol plays an important role in the amino acid decreasing effect of ethanol. In this study the lowest dose used (0.66 g kg-1) was calculated to be high enough to keep the enzyme systems involved in ethanol oxidation saturated during the 60 min course of the experiment. The observation that the ethanol-induced decrease in plasma amino acid levels was more pronounced with higher ethanol doses indicates that not only the oxidation of ethanol but also ethanol itself is important in the effect of ethanol on plasma amino acid concentrations.

Increased adherence to vaginal epithelial cells and phagocytic killing of gonococci and urogenital meningococci associated with heat modifiable proteins

Urogenital Neisseria meningitidis were characterized with regard to serogroup, colony morphology, the presence of heat modifiable proteins (HMP), attachment to human vaginal and buccal epithelial cells, and phagocytic killing by polymorphonuclear leukocytes. The findings were compared with those on gonococci, and with those on meningococci isolated from blood or cerebrospinal fluid, with regard to colony morphology, HMP and piliation. The opacity colony morphology characteristic could be used to predict the presence of HMP in gonococci but not in meningococci, and sodium dodecyl sulphate polyacrylamide gel electrophoresis had to be used to demonstrate this surface protein. The urogenital meningococci, serogroup Y, attached significantly more efficinetly to vaginal epithelial cells in the presence of HMP and behaved in this respect like those of gonococci. Gonococci and meningococci containing HMP were more sensitive to phagocytic killing than those without HMP. Meningococci from opaque and transparent colonies and isolated from patients with meningococcal disease had no demonstrable HMP. They showed low adherence to vaginal and buccal epithelial cells, with no difference between organisms from opaque or transparent colonies.

Diurnal rhythms in rat plasma amino acids

To obtain detailed data on the diurnal rhythm in rat plasma amino acids, groups of rats were killed every two hours during 24 hours and the amino acids in plasma were measured. By using such a short interval between the blood samples, it was possible to reveal differences in rhythmicity between the various amino acids, more detailed than those previously described. Furthermore, it was found that those large neutral amino acids (LNAA) which compete with each other for the carrier mediated transport from plasma into the brain demonstrated different rhythms, whereby also the relation between these competing amino acids varied during the day. This finding might have implications for the transport of the various LNAAs into the brain, and secondarily also for the synthesis of the monoaminergic neurotransmitters in the neurons, for which the LNAAs tyrosine and tryptophan serve as precursors.

Effect of 4-methylpyrazole on ethanol-induced decrease in rat plasma amino acids

It has been shown earlier that an acute dose of ethanol causes an immediate decrease in the concentration of most plasma amino acids, and that this decrease involves both beta-adrenergic and adrenocortical mechanisms. In this work is shown that the oxidation of ethanol also plays an important role in the amino acid decreasing effect. Male rats were pretreated with 4-methylpyrazole, an inhibitor of liver alcohol dehydrogenase, in doses causing an 85% inhibition of the ethanol elimination. In this group the ethanol-induced decrease in amino acids was much less pronounced than in a control group pretreated with saline.

Factors of importance for prognosis in men with angina pectoris derived from a random population sample. The Multifactor Primary Prevention Trial, Gothenburg, Sweden

A random population sample of middle-aged men from the Primary Prevention Trial was followed for 11.3 years from a first screening when different factors known to be associated with coronary artery disease (CAD) were analyzed. Men with uncomplicated angina pectoris (AP) (n = 167) derived from this population had an incidence of fatal and nonfatal CAD events 3 times higher than that of men without AP or myocardial infarction (n = 5,774). Men with myocardial infarction with or without AP had an incidence of CAD events 7 to 8 times higher than that of men without AP or myocardial infarction. Similar differences were found for new cases of uncomplicated AP (n = 128) and myocardial infarction detected at a second screening after 4 years and followed for 7.3 years. Pooled data from this series of men with uncomplicated AP showed the following factors to be associated in multivariate analysis with nonfatal or fatal CAD endpoints during follow-up: elevated serum cholesterol, elevated blood pressure, smoking and attack score. The risk increase associated with the first 3 factors was similar to the general population. These findings indicate that the same factors affecting prognosis after a first appearance of AP affect similarly patients with myocardial infarction and clinically healthy subjects. Preventive measures against these risk factors seem to be of similar importance among patients with AP, post-infarct patients and healthy subjects.