Solvent-induced chronic toxic encephalopathy

Chlorinated solvents, especially trichloroethylene, have been extensively used for metal degreasing since the beginning of this century. There have been case reports of cranial nerve damage and symptoms of acute and reversible encephalopathy. However, another issue during the last decade is the possible existence of a syndrome of chronic cerebral dysfunction. Our study deals with the risk of developing a state of psychoorganic syndrome after long-term exposure to solvents, mainly trichloroethylene. In this historical cohort study, 96 metal degreasers participated in a clinical medical and psychological examination. The risk of developing psychoorganic syndrome was proportional to the exposure duration, to increasing age, and to decreasing primary intellectual level. Using logistic regression analysis, there was a significantly increased risk of developing psychoorganic syndrome from solvent exposure. There was an odds ratio of 5.6 (0.93-34.3) for psychoorganic syndrome in the medium-exposed group. In the most highly exposed group, with a mean full-time exposure duration of 11 years, there was a significantly increased risk of psychoorganic syndrome, the adjusted odds ratio was 11.2 (1.9-66.6). None of four other potential confounders (arteriosclerotic disease, neurologic/psychiatric disease, alcohol abuse, and current solvent exposure) had any significant associations to psychoorganic syndrome.

[Cardiac events after myocardial infarction treated with streptokinase. The prognostic value of symptom-limited ECG on day 7]

One hundred and forty-seven consecutive patients admitted with suspected acute myocardial infarction (AMI) were treated with streptokinase. On day 7 after AMI 107 patients performed a symptom-limited exercise test (bicycle ergometer). Thirty-four of the tested patients developed at least one cardiac event (reinfarction, cardiac death, decided myocardial revascularization) during follow-up (30 months). Exercise induced ST-depression was more frequent among patients with cardiac events than among those without cardiac events (chi 2-test, p < 0.05). With multiple logistic regression analysis (BMPD) the following variables were found to have independent prognostic value for the development of new cardiac events: low maximal heart-rate during the exercise test, long duration of acute symptoms before streptokinase treatment and male sex. Exercise-induced ST-depression had no prognostic value in the BMPD-analysis. Exercise testing can be carried out with safety and supplies prognostic information concerning future cardiac events in patients with streptokinase-treated AMI.

Clinical neurological findings among metal degreasers exposed to chlorinated solvents

Among industrial solvents in present use trichloroethylene belongs to those which have been the concern of most neurological and occupational investigations since the beginning of this century. Reports on a broad spectrum of neurotoxicity are however mostly based on case-studies and accidental circumstances. The object of this study was to examine clinical neurological manifestations after long-term exposure to degreasing solvents, mainly trichloroethylene. The population was 99 metal degreasers, the design a historical cohort study. The most marked finding was a highly significant dose-response relation between solvent exposure and motor dyscoordination--a finding that was retained after multivariate control of relevant confounders. Vibration thresholds increased by solvent exposure at bivariate level, but the multivariate analysis showed that age was explaining most of the increase. No significant cranial nerve dysfunction was found.

Pancreatic beta-cell function and glucose metabolism in human segmental pancreas and kidney transplantation

beta-Cell function and glucose metabolism were studied in eight insulin-dependent diabetic recipients of combined segmental pancreas and kidney transplant with peripheral insulin delivery (Px), in eight nondiabetic kidney-transplant individuals (Kx), and in eight normal subjects (Ns) after three consecutive mixed meals. All subjects had normal fasting plasma glucose, but increased basal levels of C-peptide were demonstrated in the transplant groups (P < 0.05 relative to Ns). Postprandial hyperglycemia was increased 14% in Kx and 32% in Px (P < 0.05), whereas compared with Ns postprandial C-peptide levels were increased three- and twofold, respectively, in Kx and Px (P < 0.05). Compared with Ns basal insulin secretion rate (combined model) was increased 2-fold in Kx and 1.4-fold in Px (P < 0.05). Maximal insulin secretion rate was reduced 25% in Px compared with Kx (P < 0.05) but not different from that of Ns (P NS). Also, maximal insulin secretion rate occurred later in Px than in controls (Tmax: Px 50 min, Kx 30 min, and Ns 32 min; P < 0.05). The total integrated insulin secretion was increased 1.4-fold in Px compared with Ns (P < 0.05) but decreased 1.4-fold compared with Kx (P < 0.05). Fasting and postprandial proinsulin-to-C-peptide molar ratios were inappropriately increased in Px compared with Kx and Ns. Basal hepatic glucose production was increased 43% in Px and 33% in Kx compared with Ns (P < 0.05). Postprandial total systemic glucose appearance was similar in all three groups, whereas peripheral glucose disposal was 15% reduced in Px (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Conformations of disaccharides by empirical force field calculations. Part V: Conformational maps of beta-gentiobiose in an optimized consistent force field

A recently optimized set of potential energy functions is used to investigate the conformational flexibility of the beta-(1-->6) glycosidic linkage in beta-gentiobiose. Relaxed Ramachandran maps in vacuo are presented in the torsional angles phi and omega, with torsional angle psi allowed to relax freely, as are all other internal degrees of freedom. The study reveals two almost iso-energetic low energy domains in (phi, psi, omega) space, and cross-sections in the low-energy domains at omega = -60 degrees and omega = 60 degrees show that more than 60% and 70% respectively of the area of the conformational maps are accessible within 40 kJ mol-1. The molecular structure in the crystal, including the exoanomeric effect, is well reproduced. The structure belongs to the potential energy well which includes the global potential energy minimum in vacuo. The most profound structural difference between the crystal structure and the calculated global minimum in vacuo is the 20 degrees deviation of the psi torsional angle (24 degrees from perfect trans). It occurs in the most flexible glucosidic degree of freedom, psi, and is caused by optimization of the hydrogen bonding network and not by the exoanomeric effect.

Electrophysiological effects of diphenylpyrazolidinone cholecystokinin-B and cholecystokinin-A antagonists on midbrain dopamine neurons

The diphenylpyrazolidinone cholecystokinin (CCK)-B antagonist LY262691 has recently been demonstrated to decrease the number of spontaneously active dopamine (DA) cells in the ventral tegmental area (A10) and substantia nigra (A9) of the anesthetized rat. In the present study, three structural analogs of LY262691 with high selectivity for CCK-B receptors, LY262684, LY191009 and LY242040, also decreased the number of spontaneously active A10 DA cells. Neither an inactive analog (LY206890) nor a CCK-A-selective analog (LY219057) affected the number of spontaneously active A10 DA cells. L-365,260, a benzodiazepine CCK-B antagonist, also decreased the number of spontaneously active A10 DA cells. In addition, the more active optical isomer of LY262691 (LY288513) caused twice as large a decrease in the number of spontaneously active A10 DA cells as the less active optical isomer (LY288512). The diphenylpyrazolidinone CCK-B antagonists, but neither the inactive nor the CCK-A selective analog, also decreased the number of spontaneously active A9 DA cells; however, none of these compounds produced catalepsy in awake animals. Single-unit recordings indicated that LY262691 administration inhibited the activity of individual A9 and A10 DA neurons. These results indicate that the firing of A9 and A10 DA neurons is suppressed specifically by antagonism of CCK-B, but not CCK-A receptors. CCK-B antagonists may therefore represent a novel class of antipsychotic drugs. Furthermore, because CCK-B antagonists have no cataleptogenic effects, they may also have a reduced propensity for producing extrapyramidal side effects. In addition, these actions on midbrain DA neurons may contribute to the known anxiolytic activity of CCK-B antagonists.

Subclinical affection of liver and kidney function and solvent exposure

The role of solvents as hepato- and nephrotoxic agents under present-day exposure levels is still unclear. The purpose of this study involving 99 metal degreasers was to examine dose-response relationships between long-term exposure of mainly trichloroethylene and a battery of liver function tests and one nephrotubular enzyme test. Serum gamma-glutamyltransferase and urinary N-acetyl-beta-glucosaminidase were elevated by increasing solvent exposure at bivariate level. The significance of this relationship, however, was not able to withstand a multiple regression analysis, with age and alcohol abuse as confounding variables. The conclusion is that of a nonsignificant association between solvent exposure and tests screening for early liver and kidney dysfunction.

Nicotine withdrawal: a behavioral assessment using schedule controlled responding, locomotor activity, and sensorimotor reactivity

Three different behavioral measures were used to assess the effects of abrupt cessation of chronic nicotine treatment. Nicotine (0, 3, or 6 mg/kg per day) was continuously administered for 12 days in rats by surgically implanting Alzet osmotic mini-pumps subcutaneously. Experiment 1 employed a light/dark discrimination task. There were no significant effects on number of responses or percent correct responding either during nicotine administration, or following cessation of nicotine. Experiment 2 examined ambulatory (locomotor) and nonambulatory activity. Chronic nicotine administration produced significant dose-dependent increases in both ambulatory and nonambulatory activity during the first 3 days of exposure. However, no significant alterations were seen in activity levels following nicotine cessation. Experiment 3 examined sensorimotor reactivity using the auditory startle response. During nicotine withdrawal, significant increases were seen in startle amplitude in both nicotine groups for 4 days. Nicotine (0.4 mg/kg, IP) administered before startle testing during the withdrawal phase attenuated the increased reactivity seen during nicotine cessation. These studies indicate that 1) rats display increased sensorimotor reactivity after cessation of chronic nicotine exposure, and 2) the expression of nicotine dependence and withdrawal is dependent on the behavioral task employed.

Lidocaine to prevent ventricular fibrillation in the prehospital phase of suspected acute myocardial infarction: the North-Norwegian Lidocaine Intervention Trial

The efficacy of lidocaine to prevent ventricular fibrillation during the prehospital phase of suspected acute myocardial infarction was assessed 3 hours after administration in a randomized controlled trial. A total of 204 patients examined within 6 hours after onset of symptoms were included, and acute myocardial infarction was later confirmed in 63% of these. Lidocaine, administered as a 100 mg intravenous bolus dose followed by a 300 mg intramuscular injection, failed to prevent ventricular fibrillation, which was observed in 2 (2.1%) of 96 patients in the lidocaine group and in 3 (3.0%) of 101 patients in the placebo group (p = 0.95; odds ratio 0.7, 95% confidence interval 0.4 to 1.3). In addition, sudden cardiac collapse with unknown heart rhythm was observed in three patients who received lidocaine (3.1%) compared with none in the placebo group (p = 0.23; odds ratio 7.6, 95% confidence interval 2.8 to 22.1). The results of this small study suggest that lidocaine, even when given in a high dose, is ineffective in preventing ventricular fibrillation when administered before hospitalization for suspected acute myocardial infarction. Prophylactic use of lidocaine in this situation may therefore not be warranted or advisable.

Glucocorticoid regulation of alkaline phosphatase, osteocalcin, and proto-oncogenes in normal human osteoblast-like cells

In humans, glucocorticoids are known to have marked effects on bone metabolism and function, including the significant regulation of osteoblast cells. To aid in the understanding of the mechanism of glucocorticoid action on normal human osteoblasts (hOB), confluent cells were analyzed for the presence of glucocorticoid receptors (GR) as well as for the effects of the glucocorticoid dexamethasone (Dex) on the expression of both the rapid responding nuclear proto-oncogenes and the late responding structural genes for bone matrix proteins. The interactions between Dex and 1,25 dihydroxy vitamin D3 (1,25 D3) on the gene expression in these cells were also examined. Using a functional receptor assay, a mean of 11,600 functional nuclear bound glucocorticoid receptors (range 6,000-22,000) was measured in fifteen separate cell strains. Northern blot analysis with a cDNA probe to the human GR was used to demonstrate the presence of a 7Kb transcript which is a candidate mRNA for GR in these cells. In agreement with previous studies, treatment of the hOB cells with Dex increased the steady state mRNA levels for alkaline phosphatase (AP) but displayed little or no effect on the mRNA levels for osteocalcin (OC) and glyceraldehyde phosphate dehydrogenase (GAPDH). Interestingly, the 1,25 D3 inductions of mRNA levels for OC were blocked by Dex but enhanced for AP. The above effects of Dex on AP and OC gene expression, including the interaction with 1,25 D3, were also shown to occur at the level of protein. The effect of Dex on the mRNA levels of the nuclear proto-oncogenes c-myc, c-fos, and c-jun was also investigated, since the oncoproteins (Fos/Jun) appear to play a role in the delayed glucocorticoid regulation of structural genes. Interestingly, Dex increased the steady state levels of c-myc, c-fos, and c-jun mRNAs in nonproliferating (confluent) hOB cells by 3.5-, 10-, and 2.0-fold, respectively, over control (untreated cells) values within one h of steroid treatment. The Dex-induced mRNA levels were transient and returned to basal values within 24 h of the steroid treatment. A reduced but qualitatively similar pattern of response was found in proliferating hOB cells. The pattern of response of these genes to glucocorticoids in hOB cells mimics the response in avian liver cells but not in reproductive cells. These results support the theory that hOB cells are target cells for glucocorticoids, and that as a primary event glucocorticoids rapidly regulate the expression of the nuclear oncoproteins Fos/Jun in these cells.

[Medical ethics and quality assurance]

Quality in medicine is by definition an ethical aim. In its common form the programme of quality control is directed at the accurate measuring of the output of health care. This programme has a good ethical foundation. We ought to know much more about results and complications, both of diagnostic and of therapeutic procedures. However, the quality assessment programme, also has potential dangers from an ethical point of view. The main problem is that it may tend to focus on simple, technical, measurable short-term indices, giving insufficient attention to important human and ethical factors. Therefore the quality control programme needs to be supplemented by other methods.

Two novel nonradioactive polymerase chain reaction-based assays of dried blood spots, genomic DNA, or whole cells for fast, reliable detection of Z and S mutations in the alpha 1-antitrypsin gene

Two new nonradioactive polymerase chain reaction (PCR)-based assays for the Z and S mutations in the alpha 1-antitrypsin gene are presented. The assays take advantage of PCR-mediated mutagenesis, creating new diagnostic restriction enzyme sites for unambiguous discrimination between test samples from individuals who are normal, heterozygous, or homozygous for the mutations. We show that the two assays can be performed with purified genomic DNA as well as with boiled blood spots. The new assays were validated by parallel testing with a technique in which PCR is combined with allele-specific oligonucleotide (ASO) probes. In all cases tested the results obtained by the different techniques were in accordance. The new assays can be used for prenatal diagnostics and can be performed directly with boiled tissue samples. Because the new assays are easy to perform and reliable, we conclude that they are well suited for routine diagnosis.

Two Novel Nonradioactive Polymerase Chain Reaction-Based Assays of Dried Blood Spots, Genomic DNA, or Whole Cells for Fast, Reliable Detection of Z and S Mutations in the α1-Antitrypsin Gene

Two new nonradioactive polymerase chain reaction (PCR)-based assays for the Z and S mutations in the alpha 1-antitrypsin gene are presented. The assays take advantage of PCR-mediated mutagenesis, creating new diagnostic restriction enzyme sites for unambiguous discrimination between test samples from individuals who are normal, heterozygous, or homozygous for the mutations. We show that the two assays can be performed with purified genomic DNA as well as with boiled blood spots. The new assays were validated by parallel testing with a technique in which PCR is combined with allele-specific oligonucleotide (ASO) probes. In all cases tested the results obtained by the different techniques were in accordance. The new assays can be used for prenatal diagnostics and can be performed directly with boiled tissue samples. Because the new assays are easy to perform and reliable, we conclude that they are well suited for routine diagnosis.

Effects of the early administration of enalapril on mortality in patients with acute myocardial infarction. Results of the Cooperative New Scandinavian Enalapril Survival Study II (CONSENSUS II)

BACKGROUND

Long-term administration of angiotensin-converting--enzyme (ACE) inhibitors has been shown to improve survival in patients with symptomatic left ventricular failure and to attenuate left ventricular dilatation in patients with myocardial infarction. We studied whether mortality could be reduced during the 6 months after an acute myocardial infarction with use of the ACE inhibitor enalapril.

METHODS

At 103 Scandinavian centers patients with acute myocardial infarctions and blood pressure above 100/60 mm Hg were randomly assigned to treatment with either enalapril or placebo, in addition to conventional therapy. Therapy was initiated with an intravenous infusion of enalapril (enalaprilat) within 24 hours after the onset of chest pain, followed by administration of oral enalapril.

RESULTS

Of the 6090 patients enrolled, 3046 were assigned to placebo and 3044 to enalapril. The life-table mortality rates in the two groups at one and six months were not significantly different (6.3 and 10.2 percent in the placebo group vs. 7.2 and 11.0 percent in the enalapril group, P = 0.26). The relative risk of death in the enalapril group was 1.10 (95 percent confidence interval, 0.93 to 1.29). Death due to progressive heart failure occurred in 104 patients (3.4 percent) in the placebo group and 132 (4.3 percent) in the enalapril group (P = 0.06). Therapy had to be changed because of worsening heart failure in 30 percent of the placebo group and 27 percent of the enalapril group (P less than 0.006). Early hypotension (systolic pressure less than 90 mm Hg or diastolic pressure less than 50 mm Hg) occurred in 12 percent of the enalapril group and 3 percent of the placebo group (P less than 0.001).

CONCLUSIONS

Enalapril therapy started within 24 hours of the onset of acute myocardial infarction does not improve survival during the 180 days after infarction.

[Treatment of mentally retarded in psychiatry]

The reform decentralizing the special care of the mentally retarded in Norway has caused concern within the Norwegian psychiatric community. The frequency of psychiatric disturbances and behaviour problems in this population is known to be high, and closing down special institutions may eventually direct more mentally retarded persons to psychiatric hospitals. Behaviour problems like poor communication skills, lack of social skills and self-care, and disruptive behaviours seem to cause more concern than the actual diagnosis. However, the same behaviour problems are found in psychiatric hospital populations, for instance among chronic schizophrenics. From a behaviour modification point of view these behaviours can be treated regardless of diagnosis. The article describes how a psychiatric hospital unit can apply behaviour modification resulting in a better life for an otherwise untreatable patient. It is recommended that behaviour modification techniques should be used concurrently with other methods of treatment used in psychiatry. As well as being potentially helpful to psychiatric patients, behaviour modification techniques will make psychiatry better equipped to treat mentally retarded people in need of psychiatric care.

Serum methylmalonic acid in uraemia

During a 3 month period we measured serum methylmalonic acid concentrations monthly in 37 patients, all on chronic haemodialysis because of end-stage kidney disease. Concentrations of methylmalonic acid in serum were above the upper reference limit in 36 of the 37 subjects. All patients were in regular cobalamin therapy, with intramuscular injections every third month, and all had normal to very high values of serum cobalamin. We found no normalization of serum methylmalonic acid during the examination period after cobalamin injections, and we could not demonstrate any relationship between concentrations of methylmalonic acid and creatinine, cobalamin and creatinine or methylmalonic acid and cobalamin in serum of these subjects. We conclude that an elevated serum methylmalonic acid concentration is a general finding in uraemic patients, and so the assay cannot be used to establish the diagnosis of tissue cobalamin deficiency in these patients.

Serum methylmalonic acid before and after oral L-isoleucine loading in cobalamin-deficient patients

Over a 1 1/2-year period, we measured concentrations of methylmalonic acid in serum before and after a standardized loading with oral L-isoleucine (100 mmol) in 13 patients admitted for evaluation of cobalamin deficiency. All patients had serum cobalamin values below 100 pmol l-1, but only 12 of the 13 patients were clinically confirmed cobalamin deficient. The clinically non-cobalamin-deficient patient had folate deficiency and was excluded. The serum methylmalonic acid concentrations before loading with isoleucine were above the upper reference limit (0.37 mumol l-1) in all the patients and L-isoleucine caused an increase in serum methylmalonic acid of more than 1.00 mumol l-1 in 11 of the 12 deficient patients. In the remaining patient the increase was 0.35 mumol l-1. The results show that a significant increase of an initially elevated serum methylmalonic acid concentration after isoleucine loading is a general finding in tissue cobalamin deficiency which strongly supports the diagnosis.

Methylmalonic Acid Concentration in Serum Not Affected in Hepatic Disease

Accumulation of methylmalonic acid may provide an early clue to deficiency of cobalamin (vitamin B12) in tissue. Metabolic abnormalities involving precursors of methylmalonic acid are frequently observed in patients with hepatic diseases. To establish whether methylmalonic acid accumulates and thereby gives false-positive test results for cobalamin deficiency, we measured the concentration of methylmalonic acid in serum of patients with various hepatic diseases. Many of the patients had increased concentrations of cobalamin in serum. In serum from 70 patients, the mean concentration of methylmalonic acid (252, SE 25 nmol/L) did not differ significantly from that found in healthy subjects (211, SE 12 nmol/L). We conclude that the assay of methylmalonic acid in serum may be useful for evaluating cobalamin status in hepatic disease with functional cobalamin deficiency despite an artificially increased normal or high concentration of cobalamin in serum.

The Tromsø study: physical fitness, self reported physical activity, and their relationship to other coronary risk factors

STUDY OBJECTIVE

The aim was to investigate the associations between physical fitness, leisure physical activity, and coronary risk factors.

DESIGN

This was a cross sectional study of a random sample of men and women, following a population survey.

SETTING

The municipality of Tromsø, Norway in 1986-1987.

PARTICIPANTS

All men born 1925-1966 and all women born 1930-1966 were invited to the survey; 21,826 subjects attended (81% of the eligible population): of these, 297 men and 312 women, randomly selected, attended the present study (attendance rates 94% in men and 89% in women).

MEASUREMENTS AND MAIN RESULTS

Fitness was tested by bicycle ergometry. Physical activity was reported on a questionnaire. Multiple regression analysis was performed with fitness and leisure activity as dependent variables, and coronary risk factors as independent variables. Fitness and leisure activity were positively related (p less than 0.05). Prominent findings for fitness were negative associations with age and smoking (p less than 0.05), and positive associations with body mass index in both sexes (p less than 0.01). HDL cholesterol and systolic blood pressure were significant predictors of fitness in men (p less than 0.01). Smoking emerged as a strong negative predictor for leisure activity in women (p less than 0.01), and a negative relation between leisure activity and total cholesterol was found in men (p less than 0.01).

CONCLUSIONS

The study indicates that coronary risk factors are more closely linked to physical fitness than to leisure physical activity.

Methylmalonic acid concentration in serum not affected in hepatic disease

Accumulation of methylmalonic acid may provide an early clue to deficiency of cobalamin (vitamin B12) in tissue. Metabolic abnormalities involving precursors of methylmalonic acid are frequently observed in patients with hepatic diseases. To establish whether methylmalonic acid accumulates and thereby gives false-positive test results for cobalamin deficiency, we measured the concentration of methylmalonic acid in serum of patients with various hepatic diseases. Many of the patients had increased concentrations of cobalamin in serum. In serum from 70 patients, the mean concentration of methylmalonic acid (252, SE 25 nmol/L) did not differ significantly from that found in healthy subjects (211, SE 12 nmol/L). We conclude that the assay of methylmalonic acid in serum may be useful for evaluating cobalamin status in hepatic disease with functional cobalamin deficiency despite an artificially increased normal or high concentration of cobalamin in serum.