Necrotizing skin and soft-tissue infections in the intensive care unit

BACKGROUND

Necrotizing skin and soft-tissue infections (NSTI) are rare but potentially life-threatening and disabling infections that often require intensive care unit admission.

OBJECTIVES

To review all aspects of care for a critically ill individual with NSTI.

SOURCES

Literature search using Medline and Cochrane library, multidisciplinary panel of experts.

CONTENT

The initial presentation of a patient with NSTI can be misleading, as features of severe systemic toxicity can obscure sometimes less impressive skin findings. The infection can spread rapidly, and delayed surgery worsens prognosis, hence there is a limited role for additional imaging in the critically ill patient. Also, the utility of clinical scores is contested. Prompt surgery with aggressive debridement of necrotic tissue is required for source control and allows for microbiological sampling. Also, prompt administration of broad-spectrum antimicrobial therapy is warranted, with the addition of clindamycin for its effect on toxin production, both in empirical therapy, and in targeted therapy for monomicrobial group A streptococcal and clostridial NSTI. The role of immunoglobulins and hyperbaric oxygen therapy remains controversial.

IMPLICATIONS

Close collaboration between intensive care, surgery, microbiology and infectious diseases, and centralization of care is fundamental in the approach to the severely ill patient with NSTI. As many aspects of management of these rare infections are supported by low-quality data only, multicentre trials are urgently needed.

Diabetes and necrotizing soft tissue infections-A prospective observational cohort study: Statistical analysis plan

BACKGROUND

Necrotizing soft tissue infections (NSTIs) are rare but carry a high morbidity and mortality. The multicenter INFECT project aims to improve the understanding of the pathogenesis, clinical characteristics, diagnosis, and prognosis of NSTIs. This article describes the study outline and statistical analyses that will be used.

METHODS

Within the framework of INFECT project, patients with NSTI at 5 Scandinavian hospitals are enrolled in a prospective observational cohort study. The goal is to evaluate outcome and characteristics for patients with NSTI and diabetes compared to patients with NSTI without diabetes. The primary outcome is mortality at 90 days after inclusion. Secondary outcomes include days alive and out of ICU and hospital, SAPS II, SOFA score, infectious etiology, amputation, affected body area, and renal replacement therapy. Comparison in mortality between patients with diabetes type 1 and 2 as well as between insulin-treated and non-insulin-treated diabetes patients will be made. Clinical data for diabetic patients with NSTI will be reported.

CONCLUSION

The study will provide important data on patients with NSTI and diabetes.

Necrotizing soft tissue infections - a multicentre, prospective observational study (INFECT): protocol and statistical analysis plan

BACKGROUND

The INFECT project aims to advance our understanding of the pathophysiological mechanisms in necrotizing soft tissue infections (NSTIs). The INFECT observational study is part of the INFECT project with the aim of studying the clinical profile of patients with NSTIs and correlating these to patient-important outcomes. With this protocol and statistical analysis plan we describe the methods used to obtain data and the details of the planned analyses.

METHODS

The INFECT study is a multicentre, prospective observational cohort study. Patients with NSTIs are enrolled in five Scandinavian hospitals, which are all referral centres for NSTIs. The primary outcomes are the descriptive variables of the patients. Secondary outcomes include identification of factors associated with 90-day mortality and amputation; associations between affected body part, maximum skin defect and Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score and 90-day mortality; 90-day mortality in patients with and without acute kidney injury (AKI) and LRINEC score of six and above or below six; and association between affected body part at arrival and microbiological findings. Exploratory outcomes include univariate analyses of baseline characteristics associations with 90-day mortality. The statistical analyses will be conducted in accordance with the predefined statistical analysis plan.

CONCLUSION

Necrotizing soft tissue infections result in severe morbidity and mortality. The INFECT study will be the largest prospective study in patients with NSTIs to date and will provide important data for clinicians, researchers and policy makers on the characteristics and outcomes of these patients.

An observational study of community-acquired severe sepsis comparing intensive care and non-intensive care patients

BACKGROUND

Most studies of sepsis are from intensive care units (ICUs). We aimed to investigate community-acquired severe sepsis in a broader population, in order to compare patients treated in or outside an ICU .

METHODS

We performed a 1-year prospective observational study with enrollment of patients from three units; a general ICU, a combined ICU/non-ICU and a medical ward with limited surveillance facilities. Hospital survivors were followed up for 5 years.

RESULTS

Overall, 220 patients were included, of which 107 received ICU treatment. The majority of abdominal (77%, P = 0.003) and genitourinary (81%, P < 0.001) infections were found in ICU and non-ICU patients, respectively. Time to first antibiotic administration was longer in ICU-patients (median 3.5 vs. 2.0 h in non-ICU patients, P = 0.011). ICU developed more organ dysfunctions than non-ICU patients (P < 0.001), nevertheless supportive therapy with vasoactive drugs and non-invasive ventilation was documented in 22% and 27% of the latter. Median hospital length of stay was 15 vs. 9 days (P = 0.001), and hospital and 5-year mortality rates 35% vs. 16% (P = 0.002) and 57% vs. 58% (P = 0.892) among ICU and non-ICU patients, respectively. Increasing age (HR 1.06 (1.04, 1.07) per year, P < 0.001), not care level during hospitalization (HR 1.19 (0.70, 2.02), P = 0.514), influenced long-term survival.

CONCLUSION

Half of the subjects with community-acquired severe sepsis never received ICU treatment. Still, use of organ supportive therapy outside the ICU was considerable. Hospital mortality was higher, whereas 5-year survival was similar when comparing ICU with non-ICU patients.

Implication of NOTCH1 gene in susceptibility to anxiety and depression among sexual abuse victims

Sexual abuse contributes to the development of multiple forms of psychopathology, including anxiety and depression, but the extent to which genetics contributes to these disorders among sexual abuse victims remains unclear. In this translational study, we first examined gene expression in the brains of rodents exposed to different early-life conditions (long, brief or no maternal separation). Hypothesizing that genes revealing changes in expression may have relevance for psychiatric symptoms later in life, we examined possible association of those genes with symptoms of anxiety and depression in a human sample of sexual abuse victims. Changes in rodent brain gene expression were evaluated by means of correspondence and significance analyses of microarrays by comparing brains of rodents exposed to different early-life conditions. Tag single-nucleotide polymorphisms (SNPs) of resulting candidate genes were genotyped and tested for their association with symptoms of anxiety and depression (Hospital Anxiety and Depression Scale) in a sample of 361 sexual abuse victims, using multinomial logistic regression. False discovery rate was applied to account for multiple testing in the genetic association study, with q-value of 0.05 accepted as significant. We identified four genes showing differential expression among animals subjected to different early-life conditions as well as having potential relevance to neural development or disorders: Notch1, Gabrr1, Plk5 and Zfp644. In the human sample, significant associations were observed for two NOTCH1 tag SNPs: rs11145770 (OR=2.21, q=0.043) and rs3013302 (OR=2.15, q=0.043). Our overall findings provide preliminary evidence that NOTCH1 may be implicated in the susceptibility to anxiety and depression among sexual abuse victims. The study also underscores the potential importance of animal models for future studies on the health consequences of early-life stress and the mechanisms underlying increased risk for psychiatric disorders.

Salivary IgA from the sublingual compartment as a novel noninvasive proxy for intestinal immune induction

Whole-saliva IgA appears like an attractive noninvasive readout for intestinal immune induction after enteric infection or vaccination, but has failed to show consistent correlation with established invasive markers and IgA in feces or intestinal lavage. For reference, we measured antibodies in samples from 30 healthy volunteers who were orally infected with wild-type enterotoxigenic Escherichia coli. The response against these bacteria in serum, lavage, and lymphocyte supernatants (antibody-in-lymphocyte-supernatant, ALS) was compared with that in targeted parotid and sublingual/submandibular secretions. Strong correlation occurred between IgA antibody levels against the challenge bacteria in sublingual/submandibular secretions and in lavage (r=0.69, P<0.0001) and ALS (r=0.70, P<0.0001). In sublingual/submandibular secretions, 93% responded with more than a twofold increase in IgA antibodies against the challenge strain, whereas the corresponding response in parotid secretions was only 67% (P=0.039). With >twofold ALS as a reference, the sensitivity of a >twofold response for IgA in sublingual/submandibular secretion was 96%, whereas it was only 67% in the parotid fluid. To exclude that flow rate variations influenced the results, we used albumin as a marker. Our data suggested that IgA in sublingual/submandibular secretions, rather than whole saliva with its variable content of parotid fluid, is a preferential noninvasive proxy for intestinal immune induction.

Olanzapine depot exposure in male rats: Dose-dependent lipogenic effects without concomitant weight gain

Treatment with second-generation antipsychotic agents such as olanzapine frequently results in metabolic adverse effects, e.g. hyperphagia, weight gain and dyslipidaemia in patients of both genders. The molecular mechanisms underlying metabolic adverse effects are still largely unknown, and studies in rodents represent an important approach in their exploration. However, the validity of the rodent model is hampered by the fact that antipsychotics induce weight gain in female, but not male, rats. When administered orally, the short half-life of olanzapine in rats prevents stable plasma concentrations of the drug. We recently showed that a single intramuscular injection of long-acting olanzapine formulation yields clinically relevant plasma concentrations accompanied by several dysmetabolic features in the female rat. In the current study, we show that depot injections of 100-250 mg/kg olanzapine yielded clinically relevant plasma olanzapine concentrations also in male rats. In spite of transient hyperphagia, however, olanzapine resulted in weight loss rather than weight gain. The resultant negative feed efficiency was accompanied by a slight elevation of thermogenesis markers in brown adipose tissue for the highest olanzapine dose, but the olanzapine-related reduction in weight gain remains to be explained. In spite of the absence of weight gain, an olanzapine dose of 200mg/kg or above induced significantly elevated plasma cholesterol levels and pronounced activation of lipogenic gene expression in the liver. These results confirm that olanzapine stimulates lipogenic effects, independent of weight gain, and raise the possibility that endocrine factors may influence gender specificity of metabolic effects of antipsychotics in the rat.

Effects of neonatal programming on hypothalamic mechanisms controlling energy balance

The prevalence of overweight and obesity in most developed countries has markedly increased during the last decades. In addition to genetic, hormonal, and metabolic influences, environmental factors like fetal and neonatal nutrition play key roles in the development of obesity. Interestingly, overweight during critical developmental periods of fetal and/or neonatal life has been demonstrated to increase the risk of obesity throughout juvenile life into adulthood. In spite of this evidence, the specific mechanisms underlying this fetal/neonatal programming are not perfectly understood. However, it is clear that circulating hormones such as insulin and leptin play a critical role in the development and programming of hypothalamic circuits regulating energy balance. Here, we review what is currently known about the impact of perinatal malnutrition on the mechanisms regulating body weight homeostasis. Understanding these molecular mechanisms may provide new targets for the treatment of obesity.

Sequence diversity of sicG among group C and G Streptococcus dysgalactiae subspecies equisimilis isolates associated with human infections in western Norway

Streptococcal inhibitor of complement (SIC) and distantly related to SIC (DRS) are well-characterized extracellular virulence factors produced by only a few emm types among group A streptococci. The prevalence and sequence variations of the sic-like gene (sicG) in clinical samples of group C and G Streptococcus dysgalactiae subspecies equisimilis (SDSE), however, have not been widely investigated. We constructed primers targeting sicG and screened 129 geographically matched and previously emm-typed non-invasive (n = 64) and invasive (n = 65) SDSE isolates for the presence of this gene. sicG was detected in seven non-invasive and eight invasive isolates belonging to eight different emm types. Within five of these emm types, sicG-negative isolates were also detected. All three isolates of stG2078.0 possessed sicG and were associated with severe soft tissue infections. Altogether, six sicG alleles (sicG1-6) were identified, and sequence variations were mainly caused by single nucleotide polymorphisms and deletion/insertion mutations. sicG1-6 were predicted to encode SICG proteins of varying length, composition, and homology with SIC and DRS proteins of group A streptococci. Our findings indicate an unpredictable association between sicG and emm type, a limited distribution and substantial sequence diversity of sicG, and no obvious relation between its presence and disease severity.

Invasive group A, C and G streptococcal disease in western Norway: virulence gene profiles, clinical features and outcomes

Invasive group A streptococcal (iGAS) disease is endemic in Norway, but data on invasive group C and group G streptococcal (iGCS/GGS) disease are lacking. We investigated the characteristics of iGAS and iGCS/GGS infections in western Norway from March 2006 to February 2009. Clinical information was retrospectively obtained from medical records. GAS and GCS/GGS isolates were emm typed and screened for the presence of 11 superantigen (SAg) genes and the gene encoding streptococcal phospholipase A₂ (SlaA). GCS/GGS isolates were also subjected to PCR with primers targeting speG(dys) . Sixty iGAS and 50 iGCS/GGS cases were identified, corresponding to mean annual incidence rates of 5.0 per 100,000 and 4.1 per 100,000 inhabitants, respectively. Skin and soft tissue infections were the most frequent clinical manifestations of both iGAS and iGCS/GGS disease, and 14 iGAS patients (23%) developed necrotizing fasciitis. The 30-day case fatality rates of iGAS and iGCS/GGS disease were 10% and 2%, respectively. emm1, emm3 and emm28 accounted for 53% of the GAS isolates, and these types were associated with severe clinical outcome. SAg gene and SlaA profiles were conserved within most of the GAS emm types, although five profiles were obtained within isolates of emm28. stG643 was the most prevalent GCS/GGS emm type, and speG(dys) was identified in 73% of the GCS/GGS isolates. Neither GAS SAg genes nor SlaA were detected in GCS/GGS. Our findings indicate a considerable burden of both iGAS and iGCS/GGS disease and a high frequency of necrotizing fasciitis caused by GAS in our community.

emm gene diversity, superantigen gene profiles and presence of SlaA among clinical isolates of group A, C and G streptococci from western Norway

In order to investigate molecular characteristics of beta-hemolytic streptococcal isolates from western Norway, we analysed the entire emm gene sequences, obtained superantigen gene profiles and determined the prevalence of the gene encoding streptococcal phospholipase A2 (SlaA) of 165 non-invasive and 34 contemporary invasive group A, C and G streptococci (GAS, GCS and GGS). Among the 25 GAS and 26 GCS/GGS emm subtypes identified, only emm3.1 was significantly associated with invasive disease. M protein size variation within GAS and GCS/GGS emm types was frequently identified. Two non-invasive and one invasive GGS possessed emm genes that translated to truncated M proteins as a result of frameshift mutations. Results suggestive of recombinations between emm or emm-like gene segments were found in isolates of emm4 and stG485 types. One non-invasive GGS possessed speC, speG, speH, speI and smeZ, and another non-invasive GGS harboured SlaA. speA and SlaA were over-represented among invasive GAS, probably because they were associated with emm3. speG^dys was identified in 83% of invasive and 63% of non-invasive GCS/GGS and correlated with certain emm subtypes. Our results indicate the invasive potential of isolates belonging to emm3, and show substantial emm gene diversity and possible lateral gene transfers in our streptococcal population.

A permeability barrier in mitochondria in ;high-energy states' against positively charged disulphides

1. In rat liver mitochondria in state 1 or 4 there is a permeability barrier against cystamine, probably in the inner membrane. 2. The permeability barrier was broken (a) when oxidative phosphorylation was uncoupled, (b) when the respiratory chain was inhibited or in anaerobiosis, or (c) when phosphate was added in the absence of exogenous substrate. Under these conditions increased amounts of [(35)S]cystamine residues were bound to matrix proteins. 3. It appears that the permeability barrier against cystamine in mitochondria reflects a ;high-energy state'. A gradual increase in the permeability for cystamine strikingly coincided with the loss of respiratory control induced by increasing concentrations of different uncoupling agents. 4. Cystamine caused uncoupling of oxidative phosphorylation in state 2 or 5, but not in state 1, 3 or 4. The uncoupling effect of cystamine was dependent on the phosphorylation potential. ATP counteracted, whereas ADP potentiated, the uncoupling by cystamine. 5. The variable penetration of cystamine appears to depend on its positive charge, since a dication derivative, NNN'N'-tetramethylcystamine, has a similar pattern of penetration, whereas an uncharged derivative, NN'-diacetylcystamine, penetrates rapidly into mitochondria irrespective of their metabolic state. 6. It is suggested that a charge barrier is present in or across the inner mitochondrial membrane in ;high-energy states'.

The relation between the levels of HDL cholesterol and the capacity for removal of triglycerides

In twenty-two men with "normal" findings clinically, by exercise ECG and laboratory tests, we performed an i.v. fat tolerance test, measurement of LCAT activity and the activities of post-heparin triglyceride lipases, and estimated serum lipids. HDL cholesterol was positively correlated to lipoprotein lipase (r=0.50, p < 0.05) and to the fractional removal rate of exogenous fat (r=0.59, p < 0.01), and negatively to the fasting levels of triglycerides (r=-0.65, p < 0.01). LCAT was neither correlated to HDL cholesterol nor to the fat removal rate. Our reseults confirm that a high triglyceride removal capacity is closely correlated to a high level of HDL. The association between the catabolism of triglyceride-rich lipoproteins and HDL was thus further substantiated.

On the pathogenesis of acquired hypo-beta-lipoproteinemia. A case associated with sideroblastic anemia

A 71-year-old previously hypercholesterolemic woman developed gradually severe hypocholesterolemia of 1.55 mmol/l. Simultaneously she developed progressive sideroblastic anemia, altered erythrocyte morphology and defective platelet function. Hypo-beta-lipoproteinemia was demonstrated with abnormal lipid composition of both very low density (VLDL), low density (LDL) and high density lipoprotein (HDL) fractions. Other plasma lipids, as well as erythrocyte lipids, were normal. The fractional catabolic rate of homologous 125I-LDL was increased to 4-5-fold, while its rate of synthesis was normal. The patient's serum contained autoantibodies directed against LDL. It is concluded that her hypo-beta-lipoproteinemia was due to autoantibodies towards LDL causing an increased catabolism without any concomitant effect on the rate of LDL synthesis. It is suggested that acquired hypo-beta-lipoproteinemia can be subdivided into two types, one in which the primary defect is an increased catabolism due to immunoelimination, and another in which the primary defect is a decreased rate of LDL synthesis.

Molecular epidemiological investigation of an outbreak of invasive beta-haemolytic streptococcal infection in western Norway

During a decade-long, high endemic situation with severe group A streptococcal disease in western Norway, a cluster of 16 patients with invasive streptococcal disease was hospitalized during a period of 11 weeks. A study including clinical characteristics and molecular epidemiology of the outbreak was initiated. Relevant clinical information was obtained from the medical records of the patients. Nine of the 16 patients had soft tissue infection, and seven of these had streptococcal toxic shock syndrome (STSS). Mortality, both overall and among those with STSS, was 25%. Streptococcal isolates from these patients were characterized by serogrouping and emm sequence typing. The emm amplicons were further characterized by sequence analysis and restriction fragment length polymorphism (emm RFLP) analysis. The streptococci were identified as group A streptococcus (GAS) in 11 patients and group G streptococcus (GGS) in four patients. The patients with GGS infection were older than the patients with GAS infection, and all patients infected with GGS had predisposing comorbidities. Isolates from 13 patients were available for emm gene analysis and found to belong to nine different emm types. Similar differentiation was obtained with emm RFLP in GAS. Hence, the outbreak was polyclonal. Results suggestive of horizontal gene transfer and recombination between the emm genes of GAS, group C streptococcus and GGS were found in the isolates from seven patients. Such genetic recombination events suggest a possible role in pathogenesis.

Antipsychotic drugs activate SREBP-regulated expression of lipid biosynthetic genes in cultured human glioma cells: a novel mechanism of action?

Several studies have reported on structural abnormalities, decreased myelination and oligodendrocyte dysfunction in post-mortem brains from schizophrenic patients. Glia-derived cholesterol is essential for both myelination and synaptogenesis in the CNS. Lipogenesis and myelin synthesis are thus interesting etiological candidate targets in schizophrenia. Using a microarray approach, we here demonstrate that the antipsychotic drugs clozapine and haloperidol upregulate several genes involved in cholesterol and fatty acid biosynthesis in cultured human glioma cells, including HMGCR (3-hydroxy-3-methylglutaryl-coenzyme A reductase), HMGCS1 (3-hydroxy-3-methylglutaryl-coenzyme A synthase-1), FASN (fatty acid synthase) and SCD (stearoyl-CoA desaturase). The changes in gene expression were followed by enhanced HMGCR-enzyme activity and elevated cellular levels of cholesterol and triglycerides. The upregulated genes are all known to be controlled by the sterol regulatory element-binding protein (SREBP) transcription factors. We show that clozapine and haloperidol both activate the SREBP system. The antipsychotic-induced SREBP-mediated increase in glial cell lipogenesis could represent a novel mechanism of action, and may also be relevant for the metabolic side effects of antipsychotics.

[Treatment of acute bacterial meningitis]

BACKGROUND

Acute bacterial meningitis requires immediate antimicrobial therapy.

MATERIALS AND METHODS

Guidelines to antimicrobial treatment of children and adults with acute bacterial meningitis are presented.

RESULTS

The most common agents causing acute bacterial meningitis are Streptococcus agalactiae in children less than one month of age, and Streptococcus pneumoniae and Neisseria meningitidis in individuals more than one month of age. If the causative bacterial agent is not known, children below one month of age should be given ampicillin and gentamicin, whereas older children and adults should be given benzylpenicillin in combination with either cefotaxime or ceftriaxone. We suggest treatment with specific antibiotic regimens in cases of known aetiology.

Thia fatty acids, metabolism and metabolic effects

(1) The chemical properties of thia fatty acids are similar to normal fatty acids, but their metabolism (see below: points 2-6) and metabolic effects (see below: points 7-15) differ greatly from these and are dependent upon the position of the sulfur atom. (2) Long-chain thia fatty acids and alkylthioacrylic acids are activated to their CoA esters in endoplasmatic reticulum. (3) 3-Thia fatty acids cannot be beta-oxidized. They are metabolized by extramitochondrial omega-oxidation and sulfur oxidation in the endoplasmatic reticulum followed by peroxisomal beta-oxidation to short sulfoxy dicarboxylic acids. (4) 4-Thia fatty acids are beta-oxidized mainly in mitochondria to alkylthioacryloyl-CoA esters which accumulate and are slowly converted to 2-hydroxy-4-thia acyl-CoA which splits spontaneously to an alkylthiol and malonic acid semialdehyde-CoA ester. The latter presumably is hydrolyzed and metabolized to acetyl-CoA and CO2. (5) Both 3- and 4-thiastearic acid are desaturated to the corresponding thia oleic acids. (6) Long-chain 3- and 4-thia fatty acids are incorporated into phospholipids in vivo, particularly in heart, and in hepatocytes and other cells in culture. (7) Long-chain 3-thia fatty acids change the fatty acid composition of the phospholipids: in heart, the content of n-3 fatty acids increases and n-6 fatty acids decreases. (8) 3-Thia fatty acids increase fatty acid oxidation in liver through inhibition of malonyl-CoA synthesis, activation of CPT I, and induction of CPT-II and enzymes of peroxisomal beta-oxidation. Activation of fatty acid oxidation is the key to the hypolipidemic effect of 3-thia fatty acids. Also other lipid metabolizing enzymes are induced. (9) Fatty acid- and cholesterol synthesis is inhibited in hepatocytes. (10) The nuclear receptors PPAR alpha and RXR alpha are induced by 3-thia fatty acids. (11) The induction of enzymes and of PPAR alpha and RXR alpha are increased by dexamethasone and counteracted by insulin. (12) 4-Thia fatty acids inhibit fatty acid oxidation and induce fatty liver in vivo. The inhibition presumably is explained by accumulation of alkylthioacryloyl-CoA in the mitochondria. This metabolite is a strong inhibitor of CPT-II. (13) Alkylthioacrylic acids inhibits both fatty acid oxidation and esterification. Inhibition of esterification presumably follows accumulation of extramitochondrial alkylthioacryloyl-CoA, an inhibitor of microsomal glycerophosphate acyltransferase. (14) 9-Thia stearate is a strong inhibitor of the delta 9-desaturase in liver and 10-thia stearate of dihydrosterculic acid synthesis in trypanosomes. (15) Some attempts to develop thia fatty acids as drugs are also reviewed.

Enhanced oxygen consumption and fatty acid metabolism in rat bone marrow with acute promyelocytic leukaemia

The metabolism of bone marrow cells during the development of acute promyelocytic leukaemia has only been scarcely characterized, even though such knowledge might improve our understanding of the mechanisms of leukemogenesis as well as of drug treatment failure. We have investigated the in vitro oxygen consumption and the metabolism of palmitate in rat bone marrow cells during development of acute promyelocytic leukaemia. As the leukaemia progressed, the cellular oxygen consumption, the beta-oxidation of palmitate and the incorporation of palmitate into phospholipids all increased markedly. Cyclophosphamide supplement led to a temporary reduction of the palmitate metabolism, but did not lower the increased oxygen consumption. We conclude that the cellular metabolic rate is elevated during the progression of acute promyelocytic leukaemia, and that this might reflect an enhanced proliferative rate of the malignant cells.

Tetradecylthioacetic acid (a 3-thia fatty acid) decreases triacylglycerol secretion in CaCo-2 cells

The effects of the hypolipidemic fatty acid analogue tetradecylthioacetic acid (TTA) on synthesis and secretion of lipoproteins in CaCo-2 cells were studied. Radiolabeled tetradecylthioacetic acid was absorbed and metabolized as efficiently as oleic acid, although a discrepancy in the metabolic fate was evident. Whereas tetradecylthioacetic acid was incorporated into cell-associated triacylglycerol to the same extent as normal fatty acids (e.g., oleic acid and palmitic acid), the amount of triacylglycerol secreted from cells incubated with tetradecylthioacetic acid was 8 to 10 times lower than the amount secreted from cells incubated with palmitic acid and oleic acid, respectively. On the other hand, there was an enhanced incorporation of tetradecylthioacetic acid into cell-associated and secreted phospholipids. Despite incorporation of tetradecylthioacetic acid into cellular triacylglycerol, unlike oleic acid, tetradecylthioacetic acid did not stimulate production of triacylglycerol-rich particles. Ultracentrifugation of basolateral media from cells incubated with tetradecylthioacetic acid revealed low amounts of triacylglycerol in the triacylglycerol-rich fraction (p < 1.006 g/ml), suggesting secretion of lipoproteins with a higher density than chylomicrons. However, the present study shows that the stimulated triacylglycerol secretion caused by oleic acid was inhibited in the presence of TTA. The decreased rate of triacylglycerol secretion from these cells was not accompanied by a stimulation of fatty acid oxidation. Based on these findings, we therefore suggest that tetradecylthioacetic acid mainly affects secretion of lipoproteins in CaCo-2 cells.

Formation of pivaloylcarnitine in heart and brown adipose tissue in the rat

Both pivaloylesterified antibiotics and pivalic acid cause pivaloylcarnitine excretion into urine in the rat and human. In the present study, the formation of pivaloylcarnitine, expressed as short-chain acylcarnitines has been observed in rats. The carnitine pool of the rats was radiolabeled by injection of L-[3H]butyrobetaine 24 h prior to exposure to pivalic acid injected i.p. or pivampicillin administered orally. The presence of pivaloylcarnitine in liver, heart, kidney, stomach, small intestine, testis, muscle, brown fat, white fat and serum was determined at zero time, 0.5, 2, 8 and 24 h after exposure to pivalic acid. After injection of pivalic acid, pivaloylcarnitine calculated as percent of free carnitine and short-chain acylcarnitines amounted to (mean +/- SD) 1.1 +/- 0, 15.4 +/- 2.5, 33.4 +/- 0.7 and 37.5 +/- 1.5% in the heart and 1.2 +/- 0.2, 20.6 +/- 9.5, 29.8 +/- 7.6 and 22.5 +/- 1.6% in brown fat after 0, 0.5, 2 and 8 h, respectively. 2 h after administration, pivaloylcarnitine calculated as percent of free carnitine and short-chain acylcarnitines was highest in the heart (20.9 +/- 7.6%) and brown fat (19.0 +/- 8.5%) in the pivalic acid-treated rat, and highest in the kidney (12.4 +/- 3.1%) and brown fat (10.2 +/- 2.8%) in the pivampicillin-treated rat. Pivaloylcarnitine percent in the liver was 2.8 +/- 0.6 in the pivalic acid-treated rat, 3.5 +/- 1.2 in the pivampicillin-treated rat and 1.3 +/- 0.4 in the control group. Pivaloylcarnitine concentration, nmol/g and nmol/organ, was highest in the heart and brown fat in both treatment groups. The present study suggests that the heart and the brown fat, but not the liver, play important roles in pivaloylcarnitine formation in the rat.

Effects of tetradecylthiopropionic acid and tetradecylthioacrylic acid on rat liver lipid metabolism

Studies of effects of 4-thia-substituted fatty acid analogues on rat liver lipid metabolism are described. With isolated hepatocytes tetradecylthiopropionate was shown to divert [1-14C]oleate from beta-oxidation into esterification, the total amount of [1-14C]oleate metabolized remaining unchanged. Tetradecylthiopropionyl-CoA was a good substrate for mitochondrial carnitine palmitoyltransferases I and II (EC 2.3.1.21), acyl-CoA oxidase (EC 1.3.3.6), for the microsomal (but not mitochondrial) glycerophosphate acyltransferase (EC 2.3.1.15), and for long-chain acyl-CoA dehydrogenase (EC 1.3.99.3). In isolated hepatocytes, its 4-thia-trans-2-enoic derivative, tetradecylthioacrylate, inhibits both beta-oxidation of, and incorporation of, [1-14C]oleate into lipids. In rat liver mitochondria tetradecylthiocrylate inhibited beta-oxidation. The degree of inhibition was not markedly increased by preincubation with tetradecylthioacrylate. Tetradecylthioacrylyl-CoA was a poor substrate for carnitine palmitoyltransferase I, and inhibited carnitine palmitoyltransferase II, microsomal glycerophosphate acyltransferase and acyl-CoA oxidase. It is concluded that the inhibitory effects of tetradecylthiopropionyl-CoA are expressed intramitochondrially, whereas primary sites of inhibition by tetradecylthioacrylyl-CoA are extramitochondrial.

Dexamethasone and insulin demonstrate marked and opposite regulation of the steady-state mRNA level of the peroxisomal proliferator-activated receptor (PPAR) in hepatic cells. Hormonal modulation of fatty-acid-induced transcription

Fatty acids and the peroxisomal proliferator, 3-tetradecylthioacetic acid (TTA) stimulate transcription of peroxisomal beta-oxidation enzymes. Recently, we have shown that their actions are markedly modulated by dexamethasone and insulin which show synergistic and inhibitory effects, respectively. In this study, we describe the regulation of the peroxisomal proliferator-activated receptor (PPAR), a member of the steroid-hormone-receptor superfamily, in a similar manner by hormones and fatty acids, supporting the hypothesis that PPAR may act as a ligand-activated transcription factor. Northern-blot analysis of steady-state mRNA levels revealed three different specific transcripts for PPAR of 10.2, 4.6 and 1.8 kb, and the former two being regulated in hepatic tissue, hepatocytes and hepatoma cells. Dexamethasone produced a pronounced overall stimulatory effect (15.3-fold) in rat hepatocytes, while insulin blocked this action completely. Minor inductions of PPAR mRNA (up to twofold induction) were observed when different fatty acids were administrated alone. However, in combination with dexamethasone, additive or synergistic actions, mounting to 24-fold stimulation, were observed, while insulin always exerted an over-riding down-regulatory effect. In non-fasting rats receiving dexamethasone, elevation of serum insulin, a slight increase in serum free fatty acids accompanied by PPAR mRNA level increases of 2.4-fold and stimulation of liver peroxisomal acyl-CoA oxidase mRNA were observed. Our results suggest that PPAR mRNA expression is under strict hormonal control and that the fatty acids and hormones affect PPAR mRNA levels in a manner analogous to the regulation of the peroxisomal beta-oxidation enzymes. The PPAR gene-regulating unit apparently contains hormone-response elements (HRE) for dexamethasone and insulin, which are thus functionally important for PPAR transcription in liver cells, making a significant enhancement or inhibition of the physiological actions of fatty acids possible.

Stimulation of fatty acid oxidation by a 3-thia fatty acid reduces triacylglycerol secretion in cultured rat hepatocytes

The present work shows that when mitochondrial beta-oxidation is stimulated by the hypolipemic, non-beta-oxidizable fatty acid analogue tetradecylthioacetic acid, there is a decrease in the secretion of triacylglycerol in cultured rat hepatocytes. In order to study the effects of tetradecylthioacetic acid in cells with different fatty acid oxidation rates, cells were grown without or with L-carnitine supplement or with addition of the beta-oxidation inhibitor L-aminocarnitine. In cells grown without and with L-carnitine in the medium, the oxidation of [1-14C]oleic acid was stimulated by tetradecylthioacetic acid, whereas it was not significantly changed by palmitic acid. In cells grown with L-aminocarnitine, oxidation of [1-14C]oleic acid was almost abolished both in the absence and in presence of tetradecylthioacetic acid. The effect of tetradecylthioacetic acid and palmitic acid on incorporation of [1-14C]oleic acid into triacylglycerol was similar under all conditions. In the presence of L-carnitine, secretion of oleic acid-labeled triacylglycerol was reduced significantly more by tetradecylthioacetic acid than by palmitic acid. The effects of tetradecylthioacetic acid and palmitic acid on secretion of oleic acid-labeled triacylglycerol were reversed in cells grown with L-aminocarnitine, where palmitic acid was the stronger inhibitor. These results were substantiated by determination of mass of triacylglycerol secreted. It is concluded that tetradecylthioacetic acid reduces secretion of triacylglycerol from rat hepatocytes mainly by acutely stimulating fatty acid oxidation.

Substrate and hormone regulation of palmitoyl-CoA synthetase in 7800 C1 Morris hepatoma cells and cultured rat hepatocytes

The effects of tetradecylthioacetic acid (TTA), insulin and dexamethasone on palmitoyl-CoA synthetase activity and its mRNA both in 7800 C1 hepatoma cells and cultured rat hepatocytes were studied. (1) When the hepatoma cells were cultivated in the presence of fatty acids or alkyl thioacetic acids (3-thia fatty acids) palmitoyl-CoA synthetase activity was increased several fold. The stronger effect was obtained with TTA, which also increased long-chain acyl-CoA synthetase mRNA significantly. TTA has no inducing effect on butyryl-CoA synthetase and little effect on octanoyl-CoA synthetase in the same cells. Dexamethasone also had inducing effect on palmitoyl-CoA synthetase in the hepatoma cells. Insulin counteracted the induction given by TTA. All of these regulation actions take place at the pretranslational level. (2) In isolated hepatocytes the activity of palmitoyl-CoA synthetase was much higher than in hepatoma cells, but it was lost rapidly in culture. The loss of the enzyme activity was slowed down in the presence of TTA and insulin, either alone or combined. Dexamethasone combined with TTA reversed the loss of enzyme activity, while dexamethasone alone even increased the loss. Analysis of palmitoyl-CoA synthetase mRNA shows that TTA prevents the loss of the enzyme activity by inducing mRNA of the enzyme, dexamethasone enhances the effect of TTA, while insulin stabilizes the enzyme activity in the cultured cells without increasing the mRNA level.

Acylcarnitine formation and fatty acid oxidation in hepatocytes from rats treated with tetradecylthioacetic acid (a 3-thia fatty acid)

In livers of rats fed a single morning dose of 100 mg tetradecylthioacetic acid (TTA) total long-chain acyl-CoA increased significantly to 3 times control levels within 6 h, then the level declined almost to control value within the next morning. Hepatic malonyl-CoA was reduced 75% 6 h after TTA treatment. From 6 to 24 h malonyl-CoA increased about 10-fold to about 3 times that of controls. Paradoxically there was nearly a 2-fold higher oxidation of both [1-14C]palmitic acid (0.5 mM) and [1-14C]oleic acid (0.5 mM) in hepatocytes isolated from rats 24 h after TTA treatment compared to controls. After 6 h, when malonyl-CoA was at a minimum in vivo, fatty acid oxidation in cells was not increased. Acylcarnitine formation in digitonin permeabilized hepatocytes isolated 24 h after administration of TTA was increased both in the absence and in the presence of malonyl-CoA. At 24 h peroxisomal palmitoyl-CoA oxidase activity was not increased. The results suggest that an increased CPT activity and increased acylcarnitine formation in the presence of malonyl-CoA is a delayed response to increased acyl-CoA levels. Furthermore, in hepatocytes isolated after 24 h incorporation of [1-14C]oleic acid into triacylglycerols was significantly reduced. The data show that in hepatocytes isolated from rats 24 h after administration of a single dose of TTA, there is a diversion of hepatic acyl-CoA from synthesis of triacylglycerols into beta-oxidation in the mitochondria.

The metabolism of tetradecylthiopropionic acid, a 4-thia stearic acid, in the rat. In vivo and in vitro studies

The metabolism of [1-14C]tetradecylthiopropionic acid (TTP), a 4-thia stearic acid, and its sulphoxide, [1-14C]texadecylsulphoxypropionic acid (TTP-SO), has been studied in intact rats, in isolated rat hepatocytes, and in rat liver mitochondria. Two pathways of oxidation (beta-oxidation and omega-oxidation) have been demonstrated. TTP is incorporated, in vivo, into tissue triacylglycerol and phospholipids, it is oxidized to CO2, and it is excreted in urine, mainly as carboxypropylsulphoxypropionic acid and a little as carboxymethylsulphoxypropionic acid. TTP-SO is metabolized, in vivo, more rapidly to the same two omega-oxidation products. In hepatocytes TTP is incorporated into triacylglycerol and phospholipids even more rapidly than stearic acid. It is recovered mainly in the 1-position of phosphatidylcholine. Some is oxidized to CO2 and acid-soluble products. TTP-SO is mainly omega-oxidized to the same metabolites as are found in urine. A small fraction is incorporated into phospholipids or oxidized to CO2. In isolated mitochondria [1-14C]TTP is converted into 14CO2, radioactive malonic semialdehyde, and addition products of malonic semialdehyde. In the presence of phenylhydrazine, malonic semialdehyde phenylhydrazone is the dominating product. In soluble extracts of mitochondria [1-14C]malonic semialdehyde is oxidized directly to 14CO2 in the presence of CoA and NAD+, probably by the (methyl)malonic acid semialdehyde dehydrogenase (EC 1.2.1.27).

The effect of adaptation on the metabolism of dodecylthioacetic acid (a 3-thia fatty acid) in rat tissues

Dodecylthioacetic acid (DTA) was both omega-hydroxylated and sulfur-oxygenated at about equal rates by the microsomal fraction from liver and kidney. Feeding tetradecylthioacetic acid (TTA) for 4 days increased omega-hydroxylation 4-fold only in the liver. The sulfur oxygenation rate was similar in liver, kidney and lung, barely detectable in heart and absent in intestinal mucosa. In isolated hepatocytes from normal rats the major metabolite from dodecylthioacetic acid was carboxypropylsulfoxyacetic acid. In hepatocytes from adapted rats, the main product was identified as bis(carboxymethyl)sulfide. In kidney perfusion experiments dodecylthioacetic acid was metabolized to carboxypropyl-sulfoxyacetic acid and preferentially excreted in the urine. In hindquarter perfusion experiments no oxidative metabolites were detected. These experiments show that only liver and kidney can metabolize dodecylthioacetic acid completely and that omega-hydroxylation in the liver is the only inducible activity, in addition to the beta-oxidation.

[Occupational health care, coordination with primary health care]

Occupational health care is a privately financed health service offered to the healthiest part of the population. It is not governed in the same way as primary health care. In this paper we conclude that the present model of organization is inadequate. The entire responsibility for organization of occupational health care should be placed with the Ministry of Health and Social Affairs. This will ensure efficient use of resources.

The effects of alkylthioacetic acids (3-thia fatty acids) on fatty acid metabolism in isolated hepatocytes

Long-chain alkylthioacetic acids (3-thia fatty acids) inhibit fatty acid synthesis from [1-14C]acetate in isolated hepatocytes, while fatty acid oxidation is nearly unaffected or even stimulated. Desaturation of [1-14C]stearate (delta 9-desaturase) is also unaffected. [1-14C]Dodecylthioacetic acid (a 3-thia fatty acid) is incorporated in triacylglycerol and in phospholipids more efficiently than [1-14C]palmitate in isolated hepatocytes. The metabolism of [1-14C]dodecylthioacetic acid to acid-soluble products (by omega-oxidation) is slow compared to the oxidation of [1-14C]palmitate. In hepatocytes from adapted rats (rats fed tetradecylthioacetic acid for 4 days) the rate of [1-14C]palmitate oxidation is increased and its rate of esterification is decreased. Stearate desaturation is also decreased. The rate of cyanide-insensitive peroxisomal fatty acid beta-oxidation is several-fold increased. The metabolic effects of long-chain 3-thia fatty acids are discussed and it is concluded that they behave essentially like normal fatty acids except for their slow breakdown due to the sulfur atom in the 3 position, which blocks normal beta-oxidation.

Thyrotropin-releasing hormone antagonism of ethanol inebriation

The effect of ethanol [1 g/kg per orally (p.o.) during 1 hr] after thyrotropin-releasing hormone (TRH) pretreatment (five doses of 20 mg p.o. during 30 hr preceding ethanol intake) was studied in a placebo-controlled, double-blind design in 11 healthy subjects. Computerized reaction tests measuring errors and reaction time, as well as clinical testing and a self evaluation (modified Osgood test) were performed before, 75, 150, and 225 min after ethanol intake. TRH treatment did not influence blood ethanol concentrations. The effect of ethanol to produce errors was substantially reduced in all three reaction tests after TRH treatment compared to placebo treatment. The reaction times were slightly increased in simple and four choice reaction tests and up to 20% increased in a complex test in the TRH-ethanol situation compared to the placebo-ethanol situation. The effects caused by ethanol were also significantly reduced in three clinical tests and in two subjective tests of inebriation by TRH treatment compared to placebo treatment. In conclusion the study demonstrated that several acute effects of ethanol intake in humans were reduced by TRH pretreatment which did not interfere with the blood ethanol concentration versus time curve.

Reduced C27-steroid 26-hydroxylase activity in heterozygotes for cerebrotendinous xanthomatosis

C27-steroid 26-hydroxylase activity in fibroblasts from two heterozygotes for CTX was determined, using an optimized enzyme assay. With 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol, 5 beta-cholestane-3 alpha,7 alpha-diol, 7 alpha-hydroxy-4-cholestane-3-one or 7 alpha-hydroxycholesterol as substrates, the activities were about 50% of those of control cells. The Km for the substrates was not increased in the CTX heterozygotes. These findings support that deficiency of the C27-steroid 26-hydroxylase is the primary enzymatic defect in CTX.

Content of sitosterol, cholestanol, and cholesterol in very low density lipoproteins of rat liver perfusate

Sterol specificity in synthesis of very low density lipoproteins in the rat liver was studied by liver perfusion after injection in vivo of sterols as double isotopes. The amounts of sterols recovered in the very low density lipoprotein fraction of the perfusate were compared with the microsomal contents, using both double isotope ratio technique and quantitation by gas chromatography. The secretion of sitosterol and cholestanol was 0.72 and 0.88 of that of cholesterol, respectively. Variations of microsomal sterol concentrations did not affect the principal results. Relative to cholesterol, one-third more of injected sitosterol was present in the liver after 24 h. Sitosterol was excreted in the bile at one-fourth the rate of cholesterol and to a larger extent as free sterol compared with cholesterol.

Hepatic 7 alpha-dehydroxylation of bile acid intermediates, and its significance for the pathogenesis of cerebrotendinous xanthomatosis

The bile acid precursor 7 alpha-hydroxy-4-cholesten-3-one was found to be enzymatically dehydroxylated at a slow rate by liver tissues from the rat, human, and guinea pig. The rat liver enzyme is localized in the microsomal fraction, has a pH optimum of about 8.5, an apparent Km of 0.03-0.04 mM, and a Vmax of 10-15 nmoles.mg protein-1.hr-1. The product from 7 alpha-hydroxy-4-cholesten-3-one was identified as cholesta-4,6-dien-3-one by its chromatographic properties and by mass spectrometry. The reaction proceeded both in air and N2, and pyridine nucleotides were not required as cofactors. In addition to the enzymatic reaction, there was a significant nonenzymatic dehydroxylation of 7 alpha-hydroxy-4-cholesten-3-one, in particular at high pH and with high concentrations of protein. No 7 alpha-dehydroxylation occurred with various 7 alpha-hydroxylated 3 beta-hydroxy-delta 5-steroids. We have previously shown that at least part of the accumulation of cholestanol in cerebrotendinous xanthomatosis (CTX) is due to accelerated 7 alpha-dehydroxylation of bile acid intermediate(s), which are further converted into cholestanol. The capacity to dehydroxylate 7 alpha-hydroxy-4-cholesten-3-one was found to be about the same in homogenates of liver biopsies from two patients with CTX as in preparations from control subjects. It is suggested that increased levels of substrate (7 alpha-hydroxy-4-cholesten-3-one) in the liver, rather than increased amounts of 7 alpha-dehydroxylase is the explanation for the accelerated 7 alpha-dehydroxylation in CTX that leads to increased biosynthesis of cholestanol.

Metabolism of the cholestanol precursor cholesta-4,6-dien-3-one in different tissues

Cerebrotendinous xanthomatosis (CTX) is a lipid storage disease where the basic defect is a lack of the mitochondrial C27-steroid 26-hydroxylase involved in bile acid synthesis (EC 1.14.13.15). Cholestanol and cholesterol accumulate in all tissues. At least part of the accumulation of cholestanol is due to a 7 alpha-dehydroxylation of early bile acid intermediates. Cholesta-4,6-dien-3-one, a proposed intermediate in this pathway, is found in increased concentrations in serum of the patients. This study shows that cholesta-4,6-dien-3-one may be metabolized to 4-cholesten-3-one and cholestanol by liver, adrenals and brain. No conversion was found in intestinal mucosa or in kidneys. The capacity to convert cholesta-4,6-dien-3-one into 4-cholesten-3-one and cholestanol varied in different tissues as well as in different species. The results are discussed in relation to the cholestanol accumulation in CTX.

Normal activity of C27-steroid 26-hydroxylase in cultured sitosterolaemia fibroblasts

The primary defect in sitosterolaemia is unknown. In some patients excretion of bile alcohols is increased, and it has been suggested that the defect is located to some step in the biosynthesis of bile acids. The activity of C27-steroid 26-hydroxylase was measured in cultured skin fibroblasts from a sitosterolaemic patient. The same assay was used as before in demonstrating deficiency of this enzyme activity in cerebrotendinous xanthomatosis (CTX), a disease in which high excretion of bile alcohols is typical. The substrate, 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol, was 26-hydroxylated to the same extent in the patient cells as in those of healthy controls. Thus, the sitosterolaemia cells have a normal activity of this enzyme.

Accumulation of 7 alpha-hydroxy-4-cholesten-3-one and cholesta-4,6-dien-3-one in patients with cerebrotendinous xanthomatosis: effect of treatment with chenodeoxycholic acid

Evidence was recently presented that an essential part of the accumulation of cholestanol in patients with cerebrotendinous xanthomatosis is due to acceleration of a novel pathway, involving 7 alpha-hydroxylated intermediates in bile acid biosynthesis as precursors (J. Clin. Invest. 1985; 75:448-456). Such intermediates accumulate in patients with cerebrotendinous xanthomatosis due to lack of the mitochondrial 26-hydroxylase involved in the major pathway for bile acid biosynthesis. The new pathway may involve the following steps: 7 alpha-hydroxycholesterol----7 alpha-hydroxy-4-cholesten-3-one----cholesta-4,6- dien-3-one----4-cholesten-3-one----cholestanol. Accurate methods have been developed for assay of 7 alpha-hydroxy-4-cholesten-3-one and cholesta-4,6-dien-3-one in serum, based on isotope dilution-mass spectrometry. The serum levels of 7 alpha-hydroxy-4-cholesten-3-one as well as those of cholesta-4,6-dien-3-one were found to be markedly elevated in the three patients with cerebrotendinous xanthomatosis. Treatment of two of the patients with chenodeoxycholic acid reduced the serum levels of the two steroids by more than 80%. The concentration of cholestanol was reduced by 72% in one patient and by 48% in the other. The possibility is discussed that accumulation of cholestanol in patients with cerebrotendinous xanthomatosis is secondary to accumulation of 7 alpha-hydroxy-4-cholesten-3-one and cholesta-4,6-dien-3-one.