Regulation of scatter factor production via a soluble inducing factor.

Scatter factor (SF) (also known as hepatocyte growth factor [HGF]) is a fibroblast-derived cytokine that stimulates motility, proliferation, and morphogenesis of epithelia. SF may play major roles in development, repair, and carcinogenesis. However, the physiologic signals that regulate its production are not well delineated. We found that various human tumor cell lines that do not produce SF secrete factors that stimulate SF production by fibroblasts, suggesting a paracrine mechanism for regulation of SF production. Conditioned medium from these cell lines contained two distinct scatter factor-inducing factor SF-IF activities: a high molecular weight (> 30 kD), heat sensitive activity and a low molecular weight (< 30 kD) heat stable activity. Further studies revealed that SF-producing fibroblasts also secrete factors that stimulate their own SF production. We characterized the < 30-kD SF-IF activity from ras-3T3 (clone D4), a mouse cell line that overproduces both SF and SF-IF. The < 30-kD filtrate from ras-3T3 conditioned medium induced four- to sixfold increases in expression of SF biologic activity, immunoreactive protein, and mRNA by multiple SF-producing fibroblast lines. Ras-3T3 SF-IF activity was stable to boiling, extremes of pH, and reductive alkylation, but was destroyed by proteases. We purified ras-3T3 SF-IF about 10,000-fold from serum-free conditioned medium by a combination of ultrafiltration, cation exchange chromatography, and reverse phase chromatography. The purified protein exhibited electrophoretic mobility of about 12 kD (reduced) and 14 kD (nonreduced) by SDS-PAGE. The identity of the protein was verified by elution of biologic activity from gel slices. Purified SF-IF stimulated SF production in a physiologic concentration range (about 20-400 pM). Its properties and activities were distinct from those of IL-1 and TNF, two known inducers of SF production. We suggest that SF-IF is a physiologic regulator of SF production.

The interaction of HGF-SF with other cytokines in tumor invasion and angiogenesis.

Scatter factor (SF) is a glycoprotein which is secreted by mesenchymal cells and which causes cohesive epithelial cell colonies to spread out, separate into individual cells, and assume a fibroblastic morphology (i.e., to "scatter"). SF is now known to be identical or nearly identical to hepatocyte growth factor, a serum-derived mitogen for various normal cell types. SF, tumor necrosis factor-alpha (TNFa), and interleukin-1 (IL1) share the ability to stimulate scattering, motility, and protease production in a variety of human tumor cell types. SF and TNFa stimulate vascular endothelial cell motility in vitro and induce angiogenesis, the formation of new blood vessels, in vivo. These factors may participate in a cytokine network which regulates tumor invasion and metastasis directly by enhancing the malignant epithelial phenotype and indirectly by inducing tumor neovascularization.

Lack of evidence for opioid tolerance or dependence in rhesus monkeys following high-dose anabolic-androgenic steroid administration.

Prolonged use of high-dose anabolic-androgenic steroids (AAS) may induce a dependence syndrome, and emerging evidence suggests that AAS effects on endogenous opioid systems may contribute to AAS abuse. The present study tested the hypothesis that high dose AAS treatment enhances endogenous opioid activity in rhesus monkeys as revealed by 1) tolerance to the antinociceptive effects of the mu opioid agonist morphine and 2) physical dependence as indicated by evidence of opioid withdrawal following administration of the opioid antagonist naloxone. Three rhesus monkeys were treated for 14 days with 3.2 mg/kg/day testosterone propionate, and the effects of morphine (0.32-10 mg/kg) and naloxone (0.01-0.32 mg/kg) were examined both before and during treatment. Morphine antinociception was evaluated using a warm-water tail-withdrawal procedure, and naloxone-precipitated withdrawal was evaluated using checked behavioral signs and measures of ventilatory rate. Chronic testosterone administration for 14 days produced a 100-fold increase in mean plasma testosterone levels. However, testosterone treatment did not significantly alter the antinociceptive effects of morphine, and naloxone did not precipitate signs of opioid withdrawal either before or during testosterone treatment. These data do not support the hypothesis that high-dose AAS treatment enhances endogenous opioid activity in rhesus monkeys in a way that produces opioid tolerance or dependence.

Combining serotonin reuptake inhibitors and bupropion in partial responders to antidepressant monotherapy.

BACKGROUND: Many patients with affective illness show partial or otherwise unsatisfactory responses to standard treatments, encouraging trials of combinations of pharmacologically dissimilar antidepressants. METHOD: Records of consecutive outpatients with affective disorders only partially responsive to treatment with a serotonin reuptake inhibitor (SRI) or bupropion, alone, were reviewed for changes in specific symptoms and risks of adverse events when an SRI and bupropion were combined. RESULTS: Greater symptomatic improvement was found in 19 (70%) of 27 subjects during a mean +/- SD of 11 +/- 14 months of combined daily use of bupropion (243 +/- 99 mg) with an SRI (31 +/- 16 mg fluoxetine-equivalents) than with either agent alone. Adverse effect risks were similar to those associated with each monotherapy, with a > 10% incidence of sexual dysfunction (N = 11, 41%), insomnia (N = 6, 22%), anergy (N = 4, 15%), and tremor (N = 3, 11%) during combined therapy; there were no seizures. CONCLUSION: With conservative dosing and close monitoring, combinations of SRIs with bupropion in this uncontrolled clinical series appeared to be safe and often more effective than monotherapy.

Clozapine therapy in refractory affective disorders: polarity predicts response in long-term follow-up.

BACKGROUND: To determine the efficacy and tolerance of long-term clozapine therapy in refractory affective illness. METHOD: Hospital records were reviewed for 193 treatment-resistant patients with a discharge diagnosis of bipolar disorder (N = 52), schizoaffective disorder (N = 81), unipolar depression (N = 14), schizophrenia (N = 40), or other disorders (N = 6) started on clozapine therapy as inpatients at McLean Hospital. An independent "best-estimate" diagnosis, based on DSM-III-R criteria, was established for each patient. Patients were contacted at least 6 months after clozapine initiation for structured follow-up interviews by raters blind to diagnosis. Patients were stratified by diagnosis, and a variety of patient characteristics and outcome measures were compared. RESULTS: Subjects were followed up a mean of 18.7 months after clozapine initiation. Bipolar manic and schizoaffective bipolar subjects had significantly better outcomes than unipolar, bipolar, and schizoaffective depressed patients on a variety of measures. One or more episodes of depression prior to clozapine predicted clozapine discontinuation (p = .01). Affective and schizoaffective subjects had baseline measures of social functioning similar to that of the schizophrenics but had significantly greater improvement in scores at follow-up. CONCLUSION: Clozapine is an efficacious and well-tolerated therapy for refractory affective illness. Manic symptomatology predicts a more favorable response than depression.

Sex differences in plasma cocaine levels and subjective effects after acute cocaine administration in human volunteers.

Gender differences after acute cocaine administration have received little attention in spite of the fact that males and females respond differently to many drugs. Seven male and seven female occasional cocaine users received both an intranasal dose of cocaine hydrochloride (0.9 mg/kg) and placebo powder in a randomized order and reported subjective effects via an instrumental joystick device and various questionnaires. Blood samples were withdrawn at 5-min intervals to assess pharmacokinetic differences. Male subjects achieved the highest peak plasma cocaine levels (144.4 +/- 17.5 ng/ml), detected cocaine effects significantly faster than females and also experienced a greater number of episodes of intense good and bad effects. Women studied during the follicular phase of their menstrual cycle had peak plasma cocaine levels of 73.2 +/- 9.9 ng/ml, which was significantly higher than when they were studied during their luteal phase (54.7 +/- 8.7 ng/ml), but there were no differences in their subjective reports of cocaine effects. In spite of the different cocaine blood levels and subjective effects, peak heart rate increases did not differ between males and females suggesting that women may be more sensitive than males to the cardiovascular effects of cocaine. These data suggest that there are significant gender and menstrual cycle differences in the response to acute intranasal cocaine administration and these differences may have implications for the differential abuse of this drug.

Opioid withdrawal during risperidone treatment.

A small but significant percentage of opioid-dependent patients will require neuroleptic treatment. Several classes of drugs have been shown to affect opioid metabolism. Two patients who were hospitalized with a diagnosis of opioid dependence received concomitant treatment with opioids and risperidone. After receiving risperidone for several days, both patients exhibited symptoms of opioid withdrawal despite having no change in their opioid doses. These withdrawal symptoms resolved soon after risperidone was discontinued. This finding suggests the possibility that risperidone may precipitate opioid withdrawal in opioid-dependent patients.

Nalbuphine hydrochloride dependence in anabolic steroid users.

Nalbuphine hydrochloride, a nonscheduled opioid agonist/antagonist analgesic, is currently approved for the treatment of pain. Recently, nalbuphine dependence was reported in three anabolic steroid users in Britain. To further document this phenomenon, we conducted interviews on eleven subjects who reported nalbuphine use. Eight subjects were clinically dependent on nalbuphine, and seven of the subjects who were asked about tolerance and withdrawal with nalbuphine acknowledged these symptoms. Eight subjects, who had never used drugs intravenously before, reported using nalbuphine by this route. Nalbuphine-related morbidity was extensive and included medical complications and psychiatric symptoms. Nalbuphine users also exhibited a high rate of comorbid Axis I disorders, including other substance misuse. Virtually all subjects described widespread nalbuphine use in the gymnasiums they frequented. These observations, together with the recent increase in nalbuphine-related articles in the lay press, suggest that nalbuphine may represent a new drug of abuse among athletes, especially those using anabolic steroids, and that nalbuphine's scheduling status may need to be re-evaluated.

Scatter factor modulates the metastatic phenotype of the EMT6 mouse mammary tumor.

EMT6 is a transplantable mouse mammary tumor cell line that has been utilized widely as a model system to study the effects of various treatments on local tumor growth and pulmonary metastasis. In this study, we examined the cellular mechanisms by which scatter factor (SF), a fibroblast-derived cytokine that stimulates epithelial cell motility, may contribute to tumor-cell dissemination, using the EMT6 model system. In vitro, SF stimulated EMT6 cell motility, invasiveness and cell-surface expression of urokinase (an enzyme required for cell migration through tissue). SF differentially stimulated EMT6 cell adhesion to and migration onto surfaces coated with collagen I and laminin. EMT6 cells treated in vitro with SF and injected i.v. into isogeneic BALB/c-Rw mice showed a small but significant increase (1.7-fold) in lung colony formation as compared with control cells. For EMT6 cells in vitro, SF had no effect on DNA synthesis, cell proliferation, cell size distribution, or in vitro colony-forming ability. Thus, the increase in lung colonization may be due to enhanced ability of SF-treated cells to adhere to subendothelial basement membrane or to invade through tissue. Studies of the tissue distribution of SF in BALB/c-Rw mice demonstrated high levels of active factor in the lung. Thus, the presence of endogenous pulmonary SF may have reduced the degree to which SF treatment stimulated EMT6 lung colonization. Significant SF activity was also found in extracts of EMT6 tumors. Cultured EMT6 cells did not produce SF, but did produce high titers of a soluble low-molecular-weight protein activity that is capable of stimulating SF production in human fibroblasts 3- to 5-fold. EMT6 tumor extracts contained high titers of a similar SF-inducing activity. These observations suggest that SF may contribute to the invasive and metastatic phenotype of EMT6 cells via a paracrine mechanism in which tumor cells induce the production of SF in stromal fibroblasts.