Disulfiram is a potent in vitro inhibitor of DNA topoisomerases.

The drug disulfiram is a thiol-reacting drug that is relatively nontoxic when used alone and has been used in the therapy of alcohol abuse for more than 40 years. Several effects of this drug have been reported for DNA synthesis and cell proliferation. In this study, the inhibitory effect of disulfiram on topoisomerase I and II activity was investigated by measuring the relaxation of superhelical plasmid pBR322 DNA. Disulfiram (1-100 microM) inhibited topoisomerase I and II in a concentration-dependent manner (IC(50) congruent with 42 +/- 8 and 30 +/- 9 microM, respectively). Consistent with the assumption that a thiol residue is involved, dithiothreitol (1 mM) markedly prevented the inhibitory effect of disulfiram on the activity of both classes of topoisomerases. These findings might explain certain aspects of disulfiram toxicity and encourage new studies to determine the usefulness of this drug and its analogues as antineoplastic agent.

Diethylnitrosamine causes pituitary damage, disturbs hormone levels, and reduces sexual dimorphism of certain liver functions in the rat.

The acute toxicity of diethylnitrosamine (DEN) to the liver has been well documented in the literature, but whether DEN also affects the endocrine parameters has been addressed in only a few studies. We thus investigated the effects of DEN on pituitary, serum hormone levels, and certain sex-differentiated liver enzymes in this study. Adult male Wister rats were intraperitoneally injected with DEN at a single dose of 200 mg/kg and were sacrificed at 1, 3, 7, and 35 days after injection; DEN-treated females were included as controls at days 7 and 35. Electron microscopic observation showed that during the first week after injection, all types of granular cells of the anterior pituitary in male animals exhibited cellular damage, including disrupted organelles and cellular structure, as well as pyknotic or lytic nuclei. Many undamaged secretory cells exhibited dilated endoplasmic reticula, hypertrophic Golgi complexes, and peripheral location of secretory granules, which usually are morphologic features of increased cellular activities. In male rats, the serum level of total testosterone decreased and the corticosterone increased 1 day after DEN treatment. The serum level of growth hormone (GH) decreased and the prolactin level increased on day 3. The hepatic expression of the male-specific cytochrome P450 2C11 (CYP2C11) decreased to 1-5% of the normal levels during the first week and was still 50% lower than the normal level on day 35, whereas the female-specific CYP2C12 expression increased only slightly. Activities of the male predominant 16alpha, 16beta, and 6beta hydroxylation of androstenedione by microsome decreased in an in vitro assay, whereas the non-sex-differentiated 7alpha hydroxylation and the female-predominant 5alpha reduction of androstenedione were unaffected. In female rats, decreased serum GH level was observed on day 7. The CYP2C12 expression in females was decreased to about 1% and 80% of the normal levels on day 7 and day 35, respectively, but the CYP2C11 expression was unchanged. These data suggest that in male rats, DEN treatment may cause pituitary damage, disturb serum hormone levels, and induce long-lasting reduction of sexual dimorphism in certain liver functions.

The effect of supplementary antioxidant therapy in patients who report hypersensitivity to electricity: a randomized controlled trial.

CONTEXT: Hypersensitivity to electricity is a proposed environmental illness of unknown etiology. Patients report a variety of symptoms that they relate to electric equipment. The afflicted individuals suffer from ill health. Many interventions have been tried but, to date, there is no one specific treatment that has been proven superior to other remedial actions. In general, there is a lack of controlled prospective studies. OBJECTIVE: To test the hypothesis that antioxidant therapy reduces symptoms and improves health in patients reporting hypersensitivity to electricity. DESIGN: Randomized, double-blind, crossover, placebo-controlled study. SETTING: Patients referred to the Environmental Illness Research Centre, Stockholm County Council. PATIENTS: Sixteen patients reporting hypersensitivity to electricity. INTERVENTION: Antioxidant supplementation (vitamins C and E, selenium). MAIN OUTCOME MEASURES: Self-reported symptoms and reported degree of hypersensitivity to electricity, serum levels of uric acid and diphenylpycrylhydrazyl (DPPH). RESULTS: The results indicated no significant differences in reported symptoms, reported hypersensitivity to electricity, or oxidative status in serum between periods of antioxidant and placebo treatments. Serum levels of DPPH and uric acid showed no correlation with the reported degree of symptoms or hypersensitivity to electricity. CONCLUSIONS: The study did not show any beneficial effect of antioxidant supplementation for patients reporting hypersensitivity to electricity. The results do not support the hypothesis that oxidative stress is a major contributor to ill health in patients who report hypersensitivity to electricity.

Tissue concentrations of tissue polypeptide antigen (TPA) and prostatic specific antigen (PSA) in 42 patients with prostatic carcinoma.

BACKGROUND: Following development of methods to quantitate biochemical markers in aspiration biopsies we showed that tissue concentration of prostate specific antigen (T-PSA) decreased with increasing malignancy while serum PSA increased. We also found that T-PSA predicts the clinical outcome better than earlier used prognostic markers. METHODS: In order to further study biochemical markers in prostatic cancer a membrane protein, tissue polypeptide antigen (TPA), which is a complex of polypeptide fragments of cytokeratins 8, 18, and 19, was quantitated in 42 patients with newly diagnosed carcinoma of the prostate. The samples had previously been analyzed for T-PSA. RESULTS: Correlation to TGM classification showed that higher malignancy is correlated to lower tissue TPA values. There is a significant positive correlation (r(s) = 0.49, P < 0.01) between T-TPA and T-PSA. Pretreatment values of T-PSA, but not T-TPA, had association to time to progression or time to death. CONCLUSIONS: Increasing prostatic malignancy is correlated to decreasing values of T-TPA. This indicates that the concentrations of membrane and secretory proteins are changed in the same direction in tissue during cancer development. Tissue TPA seem to have no prognostic value in endocrine treatment of prostatic carcinoma.

Expression of nitric oxide synthases in subcutaneous adipose tissue of nonobese and obese humans.

Studies have shown evidence of production of nitric oxide (NO) in adipose tissue, as well as inhibition of lipolysis by NO. We have analyzed nitric oxide synthase (NOS) expression in subcutaneous adipose tissue from 13 nonobese and 18 obese male subjects. Using a competitive reverse transcription polymerase chain reaction method, endothelial (eNOS) and inducible (iNOS), but not neuronal (nNOS), nitric oxide synthase mRNA expression was detected in isolated fat cells and pieces of adipose tissue. Tissue mRNA levels for eNOS were 3,814 +/- 825 and 5,956 +/- 476 amol/mg RNA (P = 0.043), and for iNOS 306 +/- 38 and 332 +/- 48 amol/mg RNA, for nonobese and obese individuals, respectively. Western blotting revealed similar eNOS protein levels in isolated fat cells and adipose tissue pieces. Protein levels for eNOS in nonobese and obese individuals, respectively, were (in optical density [OD] units per mm(2) per 100 microgram of total protein) 0.11 +/- 0.08 and 2.80 +/- 1.30 (P = 0.043). iNOS protein was detectable, but not measurable, at low levels in a subset of obese patients (3 of 10). iNOS protein levels could not be detected in nonobese individuals. Hormone-sensitive lipase (HSL), the key regulating enzyme in lipolysis, is reduced in obesity. The expression of HSL protein in subcutaneous adipose tissue was studied in the same subset of patients; in agreement with previous results, HSL levels were reduced in obese subjects: 4.64 +/- 1.10 and 1.27 +/- 0.35 (P = 0.012) in nonobese and obese subjects, respectively. In conclusion, this study shows that eNOS and iNOS, but not nNOS, are present in human subcutaneous adipose tissue. Gene expression and protein levels of eNOS are increased, whereas HSL protein levels are decreased in obesity. It is speculated that increased NO production, preferably by eNOS, and decreased HSL levels may cause decreased subcutaneous adipose tissue lipolysis in obesity. synthases in subcutaneous adipose tissue of nonobese and obese humans.

Early effects of protein kinase modulators on DNA synthesis in rat cerebral cortex.

By using tissue miniunits, protein kinase modulators, and topoisomerase inhibitors in short-term incubation (0-90 min) we studied (1) the role of protein phosphorylation in the immediate control of DNA replication in the developing rat cerebral cortex and (2) the mechanism of action for genistein-mediated DNA synthesis inhibition. Genistein decreased the DNA synthesis within less than 30 min. None of the other protein kinase inhibitors examined (herbimycin A, staurosporine, calphostin-C) or the protein phosphatase inhibitor sodium orthovanadate inhibited DNA synthesis and they did not affect the genistein-mediated inhibition. The selective topoisomerase inhibitors camptothecin and etoposide decreased the DNA synthesis to an extent similar to that of genistein and within less than 30 min. In addition, the effects of these substances on topoisomerase I and II were studied. Etoposide and genistein but not herbimycin A, staurosporine, or calphostin-C strongly inhibited the activity of topoisomerase II. Our results (1) strongly suggest that the net rate of DNA replication during the S phase of the cell cycle is independent of protein phosphorylation and (2) indicate that the early inhibitory effect of genistein on DNA synthesis is mediated by topoisomerase II inhibition rather than protein tyrosine kinase inhibition.

Gynostemma pentaphyllum: identification of major sapogenins and differentiation from Panax species.

Four main dammarane-type aglycones of gypenosides, extracted from the aerial parts of Gynostemma pentaphyllum were identified by gas chromatography-mass spectrometry. By detecting these aglycones as well as the aglycones of ginsenosides, a difference in sapogenin composition between Gynostemma pentaphyllum and Panax species was observed, which can be used in the differentiation of these plant drugs.

Chronic fatigue syndrome differs from fibromyalgia. No evidence for elevated substance P levels in cerebrospinal fluid of patients with chronic fatigue syndrome.

Levels of substance P were determined in the cerebrospinal fluid (CSF) in 15 patients with chronic fatigue syndrome (CFS). All values were within normal range. This is in contrast to fibromyalgia (FM). The majority of patients with FM have increased substance P values in the CSF. The results support the notion that FM and CFS are different disorders in spite of overlapping symptomatology.

Fast and sensitive method for simultaneous measurement of cell proliferation rate and drug sensitivity in rat cerebral cortex.

A proliferation assay based on the production of mini-units of tissue was adopted and modified for the simultaneous determination of cell proliferation rate and the effect of genistein in rat cerebral cortex. Mini-units of tissue were produced from rat cerebral cortex immediately after killing the animal and incubated with culture medium containing 3H-methyl-thymidine during 90 min. The proliferation rate was assessed by measurement of 3H-methyl-thymidine incorporation into trichloroacetic acid insoluble material/mg of protein/min. The mini-unit method preserves the neural-cell topological relation existing in vivo and, in addition, has several additional advantages: (1) the short incubation time required limits the metabolic changes, (2) the sensitivity to drugs can be assessed simultaneously with the cell proliferation rate, (3) the complete procedure can be performed within 4-6 h, and (4) many experiments can be performed with the tissue from one animal. Genistein in doses from 10 to 100 microM inhibited cell proliferation in a concentration-dependent manner. The percentage of inhibition was highest in young animals and decreased with increasing age. This method is a powerful tool for the study of drugs with short-time onset mechanisms of action and can be useful for the screening of new drugs.

Early inhibition of DNA synthesis in the developing rat cerebral cortex by the purine analogues olomoucine and roscovitine.

The effects of the cyclin-dependent kinase (CDK) inhibitors olomoucine and roscovitine on DNA synthesis were studied using short time incubation (30-90 minutes). Both purine analogues at concentrations from 1-100 microM decreased the DNA synthesis of rat brain cortex in a dose-dependent manner and the maximum effect occurred within 30 min of incubation. Staurosporine, another potent CDK inhibitor did not affect the DNA synthesis in the concentration range 1-250 nM. These results indicate that olomoucine and roscovitine block DNA synthesis by a mechanism independent of CDK inhibition. We propose that the cellular effects of olomuocine and roscovitine on the cell cycle are at least in part due to this early inhibitory effect on DNA synthesis.

p-Aminobenzoic acid, but not its metabolite p-acetamidobenzoic acid, inhibits thrombin induced thromboxane formation in human platelets in a non NSAID like manner.

We have previously shown that p-aminobenzoic acid (PABA) is acetylated by several cell lines and most peripheral blood cells, including platelets, to p-acetamidobenzoic acid (PACBA). The structural similarity of PABA and PACBA to local anesthetics and some non steroidal anti inflammatory drugs urged us to perform the present investigation. When human platelets were stimulated with thrombin to liberate AA, we found that PABA inhibited the production of thromboxane (TxB2) as measured with enzyme-linked immunosorbent assay. The inhibition was reversible and observed at PABA concentrations ranging between 55 and 1000 microM. At 328 microM PABA the production of TxB2 diminished by 87% (p = 0.013). PACBA in the same doses did not affect the production of TxB2. When platelets were incubated with [1-14C]AA, in the presence of PABA, the production of [1-14C]TxB2 was only slightly inhibited, according to analysis by high pressure liquid chromatography. Obviously PABA is not mainly acting as a prostaglandin H (cyclooxygenase) or Tx synthase inhibitor. It is rather affecting a step prior to thromboxane production, most likely the liberation of the precursor AA. In conclusion, our results demonstrate for the first time that PABA, a substance occurring in nature, inhibits endogenous TxB2 synthesis in human platelets and might thus exert profound effects on platelet AA metabolism.

Gas chromatographic-mass spectrometric determination of 20(S)-protopanaxadiol and 20(S)-protopanaxatriol for study on human urinary excretion of ginsenosides after ingestion of ginseng preparations.

An improved gas chromatographic-mass spectrometric method (GC-MS) with a fast solid-phase extraction on a newly introduced C18 microcolumn, was applied to study the urinary excretion 20(S)-protopanaxadiol and 20(S)-protopanaxatriol glycosides in man after oral administration of ginseng preparations. Using panaxatriol as internal standard, 20(S)-protopanaxadiol and 20(S)-protopanaxatriol (the aglycones of ginsenosides) could be determined at a detection level of a few ng per ml urine by GC-MS with selected-ion monitoring after their release from glycosides which occur in urine. The extraction recovery of ginsenosides from urine was more than 80% and the intra-assay coefficient of variation was less than 5.0%. The results after intake of single doses of ginseng preparations demonstrated a linear relation between the amounts of ginsenosides consumed and the 20(S)-protopanaxatriol glycosides excreted in urine. About 1.2% of the dose was recovered in five days.

Effects of perinatal asphyxia on the mesostriatal/mesolimbic dopamine system of neonatal and 4-week-old male rats.

The present study was undertaken in order to study the effects of perinatal asphyxia on tyrosine hydroxylase (TH) activity, dopamine levels and turnover, and dopamine metabolites (3,4-dihydroxyphenylacetic acid, DOPAC, homovanillic acid, HVA, and 3-methoxytyramine, 3-MT, analyzed by high-performance liquid chromatography, HPLC) measured in the basal ganglia of the 20- to 40-min-old newborn and 4-week-old male rat. Asphyxia was induced in pups by placing the fetuses, still in their uterus horns removed by hysterectomy from pregnant rats at full term, in a 37 degrees C water bath for 15-16 min or 19-20 min. Following asphyxia, the uterus horns were opened, and the pups were removed and stimulated to breathe. A 100% and 50-80% pup survival was obtained following 15-16 min and 19-20 min of asphyxia, respectively. Acute changes were studied in brains from newborn pups 20-40 min after delivery, and long-term changes were studied in brains from 4-week-old rats. No changes in TH-activity could be observed in the substantia nigra/ventral tegmental area (SN/VTA), the striatum, or the accumbens nucleus/olfactory tubercle (ACC/TUB), in the newborn or the 4-week-old rat. In the newborn rat, 19-20 min of asphyxia increased (as compared to controls) dopamine levels in the SN/VTA to 136 +/- 14% and in the ACC/TUB to 160 +/- 10%, indicating an increased synthesis and/or release of dopamine. DO-PAC levels were increased in the SN/VTA to 150 +/- 14% and in the ACC/TUB to 151 +/- 10%, and HVA levels were increased to 152 +/- 16% in the striatum and to 117 +/- 4% in the ACC/TUB. Following 15-16 min of asphyxia, dopamine levels were increased to 130 +/- 12% in the ACC/TUB, and DOPAC levels were increased to 135 +/- 6% and 130 +/- 12% in the SN/VTA and the ACC/TUB, respectively. This suggests that the increased dopamine levels may preferably reflect an increased release of dopamine following perinatal asphyxia. In the 4-week-old rat, dopamine levels were decreased in the SN/VTA to 71 +/- 4%, in the striatum to 52 +/- 8%, and in the ACC/TUB to 53 +/- 7%, following 19-20 min of perinatal asphyxia as compared to controls. No changes were observed in DOPAC, HVA, or 3-MT levels, indicating that the reduced dopamine levels reflect a reduced dopamine synthesis following perinatal asphyxia. A decrease in dopamine utilization was observed in the striatum to 15 +/- 8% and in the ACC/TUB to 9 +/- 13% following 19-20 min of perinatal asphyxia as compared to controls. This indicates that perinatal asphyxia produced long-lasting reductions in activity in the mesostriatal/mesolimbic dopamine systems in the 4-week-old rat.

Role of the pituitary in tumor promotion with ethinyl estradiol in rat liver.

Synthetic estrogens act as tumor promoters in rat liver. Because estrogen treatment markedly increases the secretion of pituitary prolactin, also shown to be a tumor promoter in rat liver, the possibility of a pituitary influence in estrogen promotion was investigated in Wistar rats. In diethylnitrosamine (DEN)-initiated hypophysectomized (hx) female rats, 24 weeks of ethinyl estradiol (EE) administration (500 microg/kg/d, intraperitoneally) did not increase the number of hepatocyte nodules and did not induce hepatocellular carcinoma (HCC) in a 2-year study. Very few placental forms of glutathione-S-transferase (GST-P)-positive foci were observed at the end of EE administration. Estrogen receptor (ER) messenger RNA (mRNA) levels in hx females were 20% of the levels in intact females. EE administration (range, 160-210 microg/kg/d, subcutaneous release pellets) to DEN-initiated intact males and females increased the number and size of hepatocyte foci. A significant increase in HCC frequency was observed in EE-treated females compared with females receiving sham-release pellets, and the latency period for HCC induction was decreased by EE in both males and females. Inhibition of prolactin (PRL) secretion by bromocriptine (Brc) (ParlodelLAR, slow intramuscular release vehicles) during EE treatment decreased the number of foci without affecting their size and markedly prolonged the latency period in both sexes. EE treatment also significantly increased the expression of c-myc, and c-jun, enhanced the levels of growth hormone receptor (GHr) mRNA in females and the levels of ER mRNA in males and "feminized" the expression of the GH-regulated genes cytochrome P450 (CYP), 2C11, CYP 2C12, and GHr in male liver. Brc administration decreased the mRNA levels of the female-predominant CYP 2C12 in EE-treated males but otherwise had no effects. In conclusion, a decreased promotive effect of EE was obtained by decreasing the PRL levels, indicating that estrogens exert at least part of their promotion effects indirectly, by increasing the levels of pituitary PRL.

Immunosuppressive properties of plasma and lymphocytes from the human retroplacental blood.

The retroplacental compartment in which maternal blood is in direct and continuous contact with trophoblasts derived from the fetus seems to be the place where maternal and fetal cells regulate each others' activities. To assess the role of the retroplacental compartment in the immune regulation of pregnancy, 10 healthy pregnant women were selected for evaluation of the immune activity of their lymphocytes and plasma from the retroplacental blood. The results showed that the proliferation and cytotoxic capacity of these lymphocytes, but not of maternal peripheral lymphocytes, against fetal cells were significantly inhibited in undirect mixed lymphocyte culture and direct cell-mediated cytotoxic assay, respectively. The plasma from retroplacental blood showed significant immunosuppressive properties and depressed the proliferation of maternal peripheral lymphocytes stimulated by fetal HLA as well as the cytotoxic activity of these cells against the fetal lymphocytes. The present data suggest that the retroplacental compartment seems to be an immunosuppressive barrier, protecting the fetus from maternal rejection.

Determination of aglycones of ginsenosides in ginseng preparations sold in Sweden and in urine samples from Swedish athletes consuming ginseng.

Recently developed gas chromatographic and gas chromatographic-mass spectrometric methods were used to characterize 17 different commercial ginseng preparations sold in Sweden. The contents of total ginsenosides per capsule or per tablet varied from 2.1 to 13.3 mg. Unlike the other preparations, a red ginseng and three liquid ginseng preparations (after releasing the sugar moieties from ginsenosides) were shown also to contain significant amounts of 20-epimers of 20(S)-protopanaxadiol and 20(S)-protopanaxatriol as well as their corresponding 24,25-hydrated compounds. In addition to the genuine and artificial sapogenins mentioned above, two epimeric pairs of prosapogenines (ginsenoside Rg3 and 20(S)-Rg3, ginsenoside Rh1 and 20(R)-Rh1) were also found in the liquid formulations. These results suggest that hydrolysis, epimerization and hydration in the side-chain of the aglycone moiety of ginsenosides may occur in the liquid formulations under weak acidic conditions (pH 3.0-3.5 with 9-10% of alcohol at room temperature). The new method was also used to determine the aglycones of ginsenosides in urine samples from Swedish athletes stating that they had consumed ginseng preparations within 10 days before urine collection. Out of the 65 samples analysed, 60 were found to contain 20(S)-protopanaxatriol. The concentrations of 20(S)-protopanaxatriol ginsenosides varied from 2 to 35 ng ml-1 urine. This is the first demonstration of uptake of ginsenosides in humans after oral administration of ginseng preparations.

Tricyclic antidepressants inhibit human natural killer cells.

The commonly used antidepressants imipramine, amitriptyline, and nortriptyline were found to significantly inhibit human natural killer (NK) cell-mediated cytolysis in vitro and suppress the stimulation of NK cells by IFN-gamma. This is a previously unrecognized biologic property of these drugs with psychotropic activity. Tricyclic antidepressants did not decrease effector-target cell conjugation formation, nor did they induce target cell resistance to NK lysis, indicating that the drugs might interfere with the killing mechanism of the effector cells. Kinetic data reveal that the drug interference is related to an early postbinding event in the activation of NK cells. Results also showed that the inhibitory effect of tricyclic antidepressants on human NK cell activity occurred in parallel to an increase in intracellular cyclic GMP concentration. However, the attenuation in the cyclic GMP formation by methylene blue, a selective inhibitor of soluble guanylate cyclase, was not accompanied by a corresponding increase in NK cell cytolytic activity. It is suggested that the stimulation of cyclic GMP was not directly involved in the inhibitory effect of antidepressants on NK cells and perhaps was a secondary phenomenon. This immune cell modulatory property of tricyclic antidepressants seems to indirectly provide evidence for the concept that human brain neurons and NK cells might share regulatory system(s).

Dihydrotestosterone and testosterone levels in men screened for prostate cancer: a study of a randomized population.

OBJECTIVE: To investigate the possible relationship between serum levels of prostate specific antigen (PSA), dihydrotestosterone (DHT), testosterone, sexual-hormone binding globulin (SHBG) and tumour stage, grade and ploidy in 65 cases of prostate cancer diagnosed in a screening study compared to 130 controls from the same population. PATIENTS, SUBJECTS AND METHODS: From a population of 26,602 men between the ages of 55 and 70 years, 2400 were selected randomly and invited to undergo screening for prostate cancer using a digital rectal examination, transrectal ultrasonography and PSA analysis. Among the 1782 attendees, 65 cases of prostate cancer were diagnosed. Each case was matched with two control subjects of similar age and prostate volume from the screening population. Frozen serum samples were analysed for PSA, DHT, testosterone and SHBG, and compared to the diagnosis and tumour stage, grade and ploidy. Comparisons between these variables, and multivariate and regression analyses were performed. RESULTS: There were significant differences in PSA level with all variables except tumour ploidy. DHT levels were slightly lower in patients with prostate cancer but the difference was not statistically significant. There was a trend towards lower DHT values in more advanced tumours and the difference for T-stages was close to statistical significance (P = 0.059). Testosterone levels were lower in patients with cancer than in the control group, but the differences were not significant. There was no correlation between testosterone levels, tumour stage and ploidy, but the differences in testosterone level in tumours of a low grade of differentiation compared to those with intermediate and high grade was nearly significant (P = 0.058). The testosterone/DHT ratio tended to be higher in patients with more advanced tumours. SHBG levels were lower in patients with cancer than in controls but the differences were not statistically significant. There were no systematic variations of tumour stage, grade and ploidy. Multivariate analysis showed that if the PSA level was known, then DHT, testosterone or SHBG added no further information concerning diagnosis, stage, grade or ploidy. Regression analysis on T-stage, PSA level and DHT showed an inverse linear relationship between PSA and DHT for stage T-3 (P = 0.035), but there was no relationship between PSA and testosterone. CONCLUSION: PSA was of value in discriminating between cases and controls and between various tumour stages and grades, but no statistically significant correlation was found for ploidy. If PSA level was known, no other variable added information in individual cases. Within a group, DHT levels tended to be lower among cases and in those with more advanced tumours. There was an inverse relationship between tumour volume, as defined by PSA level, and 5 alpha-reductase activity, as defined by DHT level, and the testosterone/DHT ratio. This trend was most obvious with T-stage. No systematic variation were found in the levels of testosterone or SHBG.

Platelet and leukocyte activation after myocardial infarction. Influence of enalapril.

In this double-blind placebo-controlled study with enalapril, 74 patients with acute myocardial infarction were followed at 0, 7, 30, 60 and 180 days after the event. Platelets and leukocytes were activated during the first 7 days. During the 6-month period fibrinogen, leukocytes, elastase, and B beta 30-43 remained elevated in 50, 15, 30 and 80% of the patients, respectively, but there was no detectable angiotensin converting enzyme activity in platelets. Enalapril did not modulate fibrinogen, leukocyte count or elastase, while B beta 30-43 peptide showed decreased levels, although the proportion of patients with values above the reference limit did not differ from placebo. In conclusion, in the 6-month post acute myocardial infarction period, while platelet function is activated only during the first week after acute myocardial infarction, fibrinogen and leukocyte function continue to be activated throughout the 6 months in a considerable proportion of patients. These signs may indicate an ongoing atherosclerotic process. Enalapril has no major influence on these reactivities.

Nitric oxide synthase pathway may mediate human natural killer cell cytotoxicity.

The present study provides evidence that the human natural killer (NK) cell effector mechanism causing target cytolysis has a requirement for L-arginine. In a deficient medium (DM) containing only salts, buffer system and glucose, NK cell-mediated cytotoxicity was found to decrease by 70% as compared to that obtained in a complete medium (CM). However, adding L-arginine to such DM could restore the activity of NK cells to the normal level. Many other components of CM, such as serum, glutamine and vitamins did not improve NK cell-mediated killing in DM. When all amino acids except L-arginine were added to DM only a partial recovery of NK cell functional cytolysis was seen. L-arginine enhanced the NK cell activity in a dose-dependent manner. Additionally, the inhibitor of both inducible and constitutive nitric oxide synthase, N-monomethyl-L-arginine (L-NMMA) inhibited NK cytolytic activity in DM supplemented with L-arginine indicating participation of nitric oxide (NO). The results also show that the stimulatory effect of L-arginine on human NK cell-mediated cytotoxicity was accompanied by an increase in NO formation as determined by accumulation of nitrite and citrulline. L-NMMA gave a dose-dependent reduction in NO generation as well. The nitrite and citrulline production dose-dependently correlated with not only the concentration of L-arginine in the cultivation medium, but also the enhanced NK cell-mediated cytolysis. Taken together, these findings could define a L-arginine/NO-linked effector mechanism in human NK cells. Nitrite and citrulline were not formed when NK cell-mediated target cell killing took place in a L-arginine-free DM supplemented with additives. Thus, it appears as if human NK cells may cause target cell killing via both NO-dependent and -independent processes.