Ultra-rapid near universal TB drug regimen identified via parabolic response surface platform cures mice of both conventional and high susceptibility

As current treatment of tuberculosis is burdensomely long, provoking non-adherence and drug resistance, effective short-course treatments are needed. Using the output-driven parabolic response surface (PRS) platform, we have identified drug regimens that treat tuberculosis more rapidly in mice than the current Standard Regimen used in humans. We show that PRS Regimen III, comprising clofazimine, SQ109, bedaquiline and pyrazinamide, rapidly sterilizes the lung both in conventionally studied BALB/c mice and in C3HeB/FeJ mice, highly susceptible mice that develop massive necrotic granulomatous lung lesions akin to those in humans, achieving relapse-free cure in only 4 weeks (p<0.0001 versus Standard Regimen). In contrast, the Standard Regimen required 16 weeks to attain lung culture negative status and 20 weeks to achieve relapse-free cure. Thus, PRS Regimen III dramatically cuts by ~80% the time to relapse-free cure in mouse tuberculosis models. PRS Regimen III, with three nonstandard drugs, can potentially treat both drug-sensitive and most drug-resistant tuberculosis.

Role of sigma 1 receptor in high fat diet-induced peripheral neuropathy

The neurobiological mechanisms of obesity-induced peripheral neuropathy are poorly understood. We evaluated the role of Sigma-1 receptor (Sig-1R) and NMDA receptor (NMDARs) in the spinal cord in peripheral neuropathy using an animal model of high fat diet-induced diabetes. We examined the expression of Sig-1R and NMDAR subunits GluN2A and GluN2B along with postsynaptic density protein 95 (PSD-95) in the spinal cord after 24-week HFD treatment in both wild-type and Sig-1R-/- mice. Finally, we examined the effects of repeated intrathecal administrations of selective Sig-1R antagonists BD1047 in HFD-fed wild-type mice on peripheral neuropathy. Wild-type mice developed tactile allodynia and thermal hypoalgesia after 24-week HFD treatment. HFD-induced peripheral neuropathy correlated with increased expression of GluN2A and GluN2B subunits of NMDARs, PDS-95, and Sig-1R, as well as increased Sig-1R-NMDAR interaction in the spinal cord. In contrast, Sig-1R-/- mice did not develop thermal hypoalgesia or tactile allodynia after 24-week HFD treatment, and the levels of GluN2A, GluN2B, and PSD-95 were not altered in the spinal cord of HFD-fed Sig-1R-/- mice. Finally, repeated intrathecal administrations of selective Sig-1R antagonists BD1047 in HFD-fed wild-type mice attenuated peripheral neuropathy. Our results suggest that obesity-associated peripheral neuropathy may involve Sig-1R-mediated enhancement of NMDAR expression in the spinal cord.

Zn2+ reduction induces neuronal death with changes in voltage-gated potassium and sodium channel currents

In the present study, cultured rat primary neurons were exposed to a medium containing N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), a specific cell membrane-permeant Zn²⁺ chelator, to establish a model of free Zn²⁺ deficiency in neurons. The effects of TPEN-mediated free Zn²⁺ ion reduction on neuronal viability and on the performance of voltage-gated sodium channels (VGSCs) and potassium channels (Kvs) were assessed. Free Zn²⁺ deficiency 1) markedly reduced the neuronal survival rate, 2) reduced the peak amplitude of I_Na, 3) shifted the I_Na activation curve towards depolarization, 4) modulated the sensitivity of sodium channel voltage-dependent inactivation to a depolarization voltage, and 5) increased the time course of recovery from sodium channel inactivation. In addition, free Zn²⁺ deficiency by TPEN notably enhanced the peak amplitude of transient outward K⁺ currents (I_A) and delayed rectifier K⁺ currents (I_K), as well as caused hyperpolarization and depolarization directional shifts in their steady-state activation curves, respectively. Zn²⁺ supplementation reversed the effects induced by TPEN. Our results indicate that free Zn²⁺ deficiency causes neuronal damage and alters the dynamic characteristics of VGSC and Kv currents. Thus, neuronal injury caused by free Zn²⁺ deficiency may correlate with its modulation of the electrophysiological properties of VGSCs and Kvs.

Astrocyte sigma-1 receptors modulate connexin 43 expression leading to the induction of below-level mechanical allodynia in spinal cord injured mice

We have previously shown using a spinal cord injury (SCI) model that gap junctions contribute to the early spread of astrocyte activation in the lumbar spinal cord and that this astrocyte communication plays critical role in the induction of central neuropathic pain. Sigma-1 receptors (Sig-1Rs) have been implicated in spinal astrocyte activation and the development of peripheral neuropathic pain, yet their contribution to central neuropathic pain remains unknown. Thus, we investigated whether SCI upregulates spinal Sig-1Rs, which in turn increase the expression of the astrocytic gap junction protein, connexin 43 (Cx43) leading to the induction of central neuropathic pain. A thoracic spinal cord hemisection significantly increased both astrocyte activation and Cx43 expression in lumbar dorsal horn. Sig-1Rs were also increased in lumbar dorsal horn astrocytes, but not neurons or microglia. Intrathecal injection of an astrocyte metabolic inhibitor (fluorocitrate); a gap junction/hemichannel blocker (carbenoxolone); or a Cx43 mimetic peptide (43Gap26) significantly reduced SCI-induced bilateral below-level mechanical allodynia. Blockade of Sig-1Rs with BD1047 during the induction phase of pain significantly suppressed the SCI-induced development of mechanical allodynia, astrocyte activation, increased expression of Cx43 in both total and membrane levels, and increased association of Cx43 with Sig-1R. However, SCI did not change the expression of oligodendrocyte (Cx32) or neuronal (Cx36) gap junction proteins. These findings demonstrate that SCI activates astrocyte Sig-1Rs leading to increases in the expression of the gap junction protein, Cx43 and astrocyte activation in the lumbar dorsal horn, and ultimately contribute to the induction of bilateral below-level mechanical allodynia.

Inhibition of FAK and VEGFR-3 binding decreases tumorigenicity in neuroblastoma

Neuroblastoma is the most common extracranial solid tumor of childhood and is responsible for over 15% of pediatric cancer deaths. Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase that is important in many facets of tumor development and progression. Vascular endothelial growth factor receptor-3 (VEGFR-3), another tyrosine kinase, has also been found to be important in the development of many human tumors including neuroblastoma. Recent reports have found that FAK and VEGFR-3 interact, and we have previously shown that both of these kinases interact in neuroblastoma. We have hypothesized that interruption of the FAK-VEGFR-3 interaction would lead to decreased neuroblastoma cell survival. In the current study, we examined the effects of a small molecule, chloropyramine hydrochloride (C4), designed to disrupt the FAK-VEGFR-3 interaction, upon cellular attachment, migration, and survival in two human neuroblastoma cell lines. We also utilized a murine xenograft model to study the impact of C4 upon tumor growth. In these studies, we showed that disruption of the FAK-VEGFR-3 interaction led to decreased cellular attachment, migration, and survival in vitro. In addition, treatment of murine xenografts with chloropyramine hydrochloride decreased neuroblastoma xenograft growth. Further, this molecule acted synergistically with standard chemotherapy to further decrease neuroblastoma xenograft growth. The findings from this current study help to further our understanding of the regulation of neuroblastoma tumorigenesis, and may provide novel therapeutic strategies and targets for neuroblastoma and other solid tumors of childhood.

Bone regeneration induced by an in situ gel-forming poloxamine, bone morphogenetic protein-2 system

The aim of this study was to confirm previously shown, in vitro osteogenic induction by the Tetronics T908 and T1307 in a critical-size, rat calvaria defect. In vivo, the osteogenic activity of the hydrogels was comparable to in vitro, but less pronounced. However, similar to in vitro, the system was strongly potentiated by incorporating 6.5 microg of bone morphogenetic protein-2 in solution or pre-encapsulated in poly(lactic-co-glycolic) acid microspheres. These two systems extended the in vivo release of bone morphogenetic protein-2, determined with 125I- bone morphogenetic protein-2, for one and two additional weeks, respectively, time enough to fill approximately 40% and 90% of the defect with well-organized bone. Furthermore, the structural characteristics of Tetronic hydrogels together with their biocompatibility, injectability, and adaptability to multiple defect sizes and shapes suggest their role as new, potential bone morphogenetic protein-2 delivery, low-cost scaffolds for minor as well as critical bone defects.

Pharmacokinetics of BMEDA after intravenous administration in beagle dogs

The pharmacokinetics of N,N-bis(2-mercapatoethly)-N',N'-diethylenediamine (BMEDA), a molecule that can form a chelate with rhenium-188 (188Re) to produce the 188Re-BMEDA-liposomes, was studied. In this work, beagles received a single injection of BMEDA, at doses of 1, 2, or 5 mg/kg; the concentration of BMEDA in the beagles' plasma was then analyzed and determined by liquid chromatography-mass spectrometry/mass spectrometry. Based on the pharmacokinetic parameters of BMEDA, we found that male and female animals shared similar patterns indicating that the pharmacokinetics of BMEDA is independent of gender differences. In addition, the pharmacokinetics of BMEDA was seen to be non-linear because the increase of mean AUC0-t and AUC0-∞ values tend to be greater than dose proportional while the mean Vss and CL values of BMEDA appeared to be dose dependent. The information on the pharmacokinetics of BMEDA generated from this study will serve as a basis to design appropriate pharmacology and toxicology studies for future human use.

A case of recurrent arrhythmia in an acute pancreatitis patient--pathophysiological explanation using shortage of 'repolarization reserve'

We report a case of a patient with acute pancreatitis who developed serious heart rhythm abnormalities on three occasions, two of which were associated with administration of the first generation antihistamine chloropyramine, and the third one with hypomagnesemia and hypokalemia. Dysrhythmic events consisted of bigeminy, multifocal ventricular extrasystoles and torsades de pointes-like ventricular tachycardia. Electrocardiographic changes in acute pancreatitis in the absence of previous heart disease can occur in more than half of the cases. Antihistamines are medications that are known to produce heart rhythm disturbances, especially the second generation drugs astemizole and terfenadine. This is the first report of chloropyramine causing dysrhythmia. It seems that acute pancreatitis patients are especially prone to heart dysrhythmia caused by different factors such as electrolyte disturbances and pronounced vagal tone. Acute pancreatitis may be added to the list of risk factors with altered 'repolarization reserve', predisposing to drug-induced QT interval prolongation and possible torsades de pointes occurrence.

Discovery and development of SQ109: a new antitubercular drug with a novel mechanism of action

Existing drugs have limited efficacy against the rising threat of drug-resistant TB, have significant side effects, and must be given in combinations of four to six drugs for at least 6 months for drug-sensitive TB and up to 24 months for drug-resistant TB. The long treatment duration has led to increased patient noncompliance with therapy. This, in turn, drives the development of additional drug resistance in a spiral that has resulted in some forms of TB being currently untreatable by existing drugs. New antitubercular drugs in development, particularly those with mechanisms of action that are different from existing first- and second-line TB drugs, are anticipated to be effective against both drug-sensitive and drug-resistant TB. SQ109 is a new TB drug candidate with a novel mechanism of action that was safe and well tolerated in Phase I and early Phase II clinical trials. We describe herein the identification, development and characterization of SQ109 as a promising new antitubercular drug.

Evaluation of an automated dental unit water system's contamination control protocol

BACKGROUND

This study addresses the efficacy of an automated decontamination protocol using the germicide 'tetra acetyl ethylene diamine (TAED) perborate' (Farmec SpA, Italy). The germicide TAED perborate protocol is used in the Castellini Dental Units fitted with an Autosteril unit (an automated device that can cycle 0.26% TAED perborate solution and sterile water for cleaning the water system between patients and overnight). Prior to testing the Autosteril and the 0.26% TAED perborate protocol on the Logos Jr Dental Unit (Castellini SpA, Italy), TAED perborate was used on a dental unit water system simulation device.

METHODS

A dental unit water system simulation device equipped with four dental unit water systems and with naturally grown and mature biofilm contamination was used in this study (three treatment units and one control). One treatment group used a simulated 5 minutes contact with TAED perborate and sterile water for irrigation; the second used a simulated 5 minutes contact with TAED perborate and 2 ppm ClO2 for irrigation; the third used a simulated 5 minutes contact with TAED perborate and municipal water for irrigation. The control group used municipal water for irrigation with no cleaning/disinfection protocols. This protocol was repeated for 30 cycles. Laser scanning confocal microscopy (LSCM) was used to study the effects on natural and mature biofilms, and R2A agar used to quantify heterotrophic plate counts in the effluent irrigant. Antimicrobial efficacy was evaluated by challenging TAED perborate with microbes and spores (M. smegmatis and B. subtilis). Deleterious effects of the germicide were evaluated on metal and nonmetal parts of dental unit water systems. Heterotrophic plate counts using R2A agar and LSCM of the lines were conducted to assess biofilm and microbial control.

RESULTS

Baseline water samples showed mean contamination >5.6 log10 cfu/ml. After initial cleaning, all three groups maintained mean contamination levels of less than 1.1 (SD <0.3) log10 cfu/ml. LSCM of baseline samples was positive for live biofilm in all groups. At the end of the study, viable biofilm was only present in the control. In the microbial challenge test, all vegetative organisms were killed within 30 seconds of contact, while spores were killed within 5 minutes. Corrosion was seen in metals used in US-manufactured dental unit materials, while not observed in those used in the Castellini Logos Jr dental unit.

CONCLUSION

In this study, the TAED perborate protocol was effective in biofilm control and control of dental treatment water contamination. Use of sterile water or 2 ppm ClO2 along with TAED treatment also controlled planktonic contamination effectively.

CLINICAL SIGNIFICANCE

Environmental biofilms contaminate dental unit water systems over time and affect the quality of dental treatment water. Contaminants include environmental biofilms, microbes, including gram-negative rods and endotoxins in high doses that are not of acceptable quality for treating patients. There are many germicidal protocols for treating this contamination and one such is the prescribed use of TAED perborate used in conjunction with sterile water for irrigation in the autosteril device, an integral component of the Castellini dental units for between patient decontamination of dental unit water systems. This study was conducted on an automated simulation dental unit water system to test the TAED perborate protocol's efficacy on naturally grown, mature environmental biofilms, it's efficacy on microbes and spores and it's effects on materials used in dental unit water systems. This translational research addresses both microbial control and material effects of TAED perborate in studying efficacy and possible deleterious effects and simulated use in dentistry. Currently, this antimicrobial use protocol is followed worldwide in the Castellini dental units that are used in day-to-day dental patient care.

Clinical evidence for the activity of tetrahydroxypropyl ethylenediamine (THPE), a new anti-aging active cosmetic

BACKGROUND/ OBJECTIVES: The cellular surface modification of superficial epidermal keratinocytes can induce immediate skin tensioning effects and may improve signs of skin aging. Tetrahydroxypropyl ethylenediamine (THPE) is an active that has been described to induce keratinocytes' morphological changes in vitro. We conducted an in vivo study to assess anti-aging clinical benefits of a THPE-containing product.

METHODS

An eight-week double-blind, randomized intra-individual placebo controlled clinical study was performed to evaluate the clinical benefits of a 2.5% THPE-containing cream. This study included 41 Caucasian women who received the THPE cream product on one side of the face and a placebo cream on the other side daily. Evaluations were performed at baseline, 45 minutes after first application, week 4 and week 8 and included clinical examination and digital photography.

RESULTS

The study demonstrated the immediate lifting effect of a 2.5% THPE-containing cream. Forty-five minutes after a single application on the face, as the skin surface smoothed out, light reflection was modified: healthy glow and radiance of the skin were significantly improved (respectively 22.9% and 40% of improvement) and skin yellowishness was reduced (7.1%). Notably, the THPE-treated side was significantly lifted, both immediately after product application (8.1%) and after 8 weeks of application (14%), compared to the placebo-treated side.

CONCLUSION

This clinical study demonstrated that the effect of a 2.5% THPE-containing cream on the keratinocytes cells leads to an immediate and long-term clinical improvement of the skin appearance (radiance and skin firmness, skin lifting) and can therefore be considered as a new anti-aging cosmetic active.

Antidepressant-like effect of PRE-084, a selective sigma1 receptor agonist, in Albino Swiss and C57BL/6J mice

PRE-084, a selective sigma receptor agonist, exhibited an antidepressant-like effect in the forced swim test (FST) in Albino Swiss and C57BL/6J mice. This effect was counteracted by BD 1047 (5 and 10 mg/kg) but not by SM-21 (3 and 10 mg/kg), which are sigma(1)- and sigma(2)-receptor antagonists, respectively. The results indicated that PRE-084 has an antidepressant-like effect in C57BL/6J and, to a lesser extent, in Albino Swiss mice. These results support the idea that sigma(1)-receptors, but not sigma(2)-receptors, contribute to the mechanism of antidepressant activity of sigma agonists in FST.

Comparative natriuretic and diuretic efficacy of theophylline ethylenediamine and of bendroflumethiazide during long-term treatment with the potent diuretic bumetanide. Permutation trial tests in patients with congestive heart failure

The additive natriuretic and diuretic effects of theophylline ethylenediamine and of bendroflumethiazide have been compared in permutation trial tests in patients with advanced congestive heart failure receiving long-term treatment with the highly potent diuretic, bumetanide. Statistical analysis of renal water and electrolyte excretion revealed that theophylline ethylenediamine, 400 mg orally, and bendroflumethiazide, 5 mg orally, had very similar effects, both quantitatively and qualitatively. The mechanism of action of the supplementary diuretics is discussed. It is concluded that theophylline ethylenediamine represents a useful alternative to thiazide diuretics when supplementary natriuretic treatment is considered in patients with congestive heart failure during long-term treatment with potent diuretics. The significance of maintaining the potassium balance during such a combined regimen is stressed.

Efficacy of Fe(o,o-EDDHA) and Fe(o,p-EDDHA) isomers in supplying Fe to strategy I plants differs in nutrient solution and calcareous soil

The FeEDDHA [iron(3+) ethylenediamine di(o-hydroxyphenylacetic) acid] is one of the most efficient iron chelates employed in the correction of iron clorosis in calcareous soils. FeEDDHA presents different positional isomers: the ortho-ortho (o,o), the ortho-para (o,p), and the para-para (p,p). Of these isomers, the p,p cannot chelate Fe in soil solution in a wide range of pH values, while both o,o and o,p can. The objective of this work was to compare the efficiency of both isomers (o,o and o,p) to provide Fe to two Strategy I plants (tomato and peach) in nutrient solution (pH approximately 6.0), as well as in calcareous soil (pH approximately 8.4; CALCIXEREPT). For this, chelates of both o,o-EDDHA and o,p-EDDHA with 57Fe (a nonradioactive isotope of Fe) were used, where the 57Fe acts as a tracer. The results obtained showed that the o,o isomer is capable of providing sufficient Fe to plants in both nutrient solution and calcareous soil. However, the o,p isomer is capable of providing sufficient Fe to plants in nutrient solution but not in calcareous soil.

Intraoperative 186Re-liposome radionuclide therapy in a head and neck squamous cell carcinoma xenograft positive surgical margin model

PURPOSE

Positive surgical margins in advanced head and neck squamous cell carcinoma (HNSCC) have a well-documented association with an increased risk of locoregional recurrence and significantly poorer survival. Traditionally, unresectable tumor is treated with postoperative radiotherapy and/or chemotherapy. However, these therapeutic options can delay treatment and increase toxicity. The potential value of intraoperative injection of liposomal therapeutic radionuclides as a locoregional, targeted therapy in unresectable advanced HNSCC was assessed in a nude rat xenograft positive surgical margin model.

EXPERIMENTAL DESIGN

The therapeutic effects of beta-emission rhenium-186 (186Re) carried by liposomes into the tumor remnants in a nude rat squamous cell carcinoma xenograft model were studied. Following the partial resection of tumor xenografts, the animals were intratumorally injected with 186Re-labeled or unlabeled (control) neutrally charged or positively charged 100-nm-diameter liposomes. Tumor size, body weight, hematology, and toxicity were monitored for 35 days posttherapy.

RESULTS

The neutral (n = 4) and cationic (n = 4) liposome control groups showed an increase in tumor growth of 288.0 +/- 37.3% and 292.2 +/- 133.7%, respectively, by day 15. The 186Re-neutral-liposome group (n = 8) and the 186Re-cationic-liposome group (n = 8) presented with an average final tumor volume of 25.6 +/- 21.8% and 28.5 +/- 32.2%, respectively, at the end of the study (day 35). All groups showed consistent increases in body weight. No significant systemic toxicity was observed in any of the animals.

CONCLUSIONS

With excellent tumor suppression and minimal side-effect profile, the intraoperative use of liposomal therapeutic radionuclides may play a role in the management of positive surgical margins in advanced HNSCC.

Activation of the spinal sigma-1 receptor enhances NMDA-induced pain via PKC- and PKA-dependent phosphorylation of the NR1 subunit in mice

BACKGROUND AND PURPOSE

Previously we demonstrated that the spinal sigma-1 receptor (Sig-1 R) plays an important role in pain transmission, although the exact mechanism is still unclear. It has been suggested that Sig-1 R agonists increase glutamate-induced calcium influx through N-methyl-D-aspartate (NMDA) receptors. Despite data suggesting a link between Sig-1 Rs and NMDA receptors, there are no studies addressing whether Sig-1 R activation directly affects NMDA receptor sensitivity.

EXPERIMENTAL APPROACH

We studied the effect of intrathecal (i.t.) administration of Sig-1 R agonists on protein kinase C (PKC) and protein kinase A (PKA) dependent phosphorylation of the NMDA receptor subunit NR1 (pNR1) as a marker of NMDA receptor sensitization. In addition, we examined whether this Sig-1 R mediated phosphorylation of NR1 plays an important role in sensory function using a model of NMDA-induced pain.

KEY RESULTS

Both Western blot assays and image analysis of pNR1 immunohistochemical staining in the spinal cord indicated that i.t. injection of the Sig-1 R agonists, PRE-084 or carbetapentane dose dependently enhanced pNR1 expression in the murine dorsal horn. This increased pNR1 expression was significantly reduced by pretreatment with the specific Sig-1 R antagonist, BD-1047. In another set of experiments Sig-1 R agonists further potentiated NMDA-induced pain behaviour and pNR1 immunoreactivity and this was also reversed with BD-1047.

CONCLUSIONS AND IMPLICATIONS

The results of this study suggest that the activation of spinal Sig-1 R enhances NMDA-induced pain via PKC- and PKA-dependent phosphorylation of the NMDA receptor NR 1 subunit.

(+)-Morphine and (-)-morphine stereoselectively attenuate the (-)-morphine-produced tail-flick inhibition via the naloxone-sensitive sigma receptor in the ventral periaqueductal gray of the rat

We have previously demonstrated that (+)-morphine and (-)-morphine pretreated spinally for 45 min stereoselectively attenuates the tail-flick inhibition produced by (-)-morphine given spinally in the mouse. The present study is then undertaken to determine if the same phenomenon observed in the mouse spinal cord can also take place in the ventral periaqueductal gray of the rat. Pretreatment with (+)-morphine for 45 min at 0.3 to 3.3 fmol dose-dependently attenuated the tail-flick inhibition produced by (-)-morphine (9 nmol) given into the ventral periaqueductal gray. Likewise, pretreatment with (-)-morphine for 45 min at a higher dose (3-900 pmol), which given alone did not affect the baseline tail-flick latency, also dose-dependently attenuated the tail-flick inhibition produced by (-)-morphine. Thus, (+)-morphine is approximately 270,000-fold more potent than (-)-morphine in attenuating the (-)-morphine-produced tail-flick inhibition. The attenuation of the (-)-morphine-produced tail-flick inhibition induced by (+)-morphine or (-)-morphine was dose-dependently reversed by (+)-naloxone (27.5 to 110 pmol) pretreatment for 50 min given into the ventral periaqueductal gray. Pretreatment with the sigma receptor antagonist BD1047 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine dihydrobromide) (11-45 nmol) for 45 min given into the ventral periaqueductal gray also reversed dose-dependently the attenuation of the (-)-morphine-produced tail-flick inhibition induced by (+)-morphine or (-)-morphine, indicating that the effects are mediated by the activation of the sigma receptors. Since (+)-morphine, (-)-morphine and (+)-naloxone do not have any affinity for the naloxone-inaccessible sigma receptors, we therefore propose that (+)-morphine and (-)-morphine attenuate the (-)-morphine-produced tail-flick inhibition via the activation of the naloxone-sensitive sigma receptor originally proposed by Tsao and Su [Tsao, L.T., Su, T.P., 1997. Naloxone-sensitive, haloperidol-sensitive, [(3)H](+)-SKF-1047-binding protein partially purified from rat liver and rat brain membranes: an opioid/sigma receptor. Synapse 25, 117-124].

Differential effects of sigma1 receptor blockade on self-administration and conditioned reinstatement motivated by cocaine vs natural reward

Growing evidence suggests a role for sigma(1) (sigma(1)) receptors in cognitive function, anxiety, depression, regulation of stress responses, and, recently, the appetitive effects of cocaine as measured by conditioned place preference. This study was designed to extend understanding of the role of sigma(1) receptors in addiction-relevant conditioned effects of cocaine by testing the effects of a potent and selective sigma(1) receptor antagonist, BD1047, on conditioned reinstatement of cocaine-seeking. To determine whether modification of conditioned reinstatement by BD1047 is selective for drug-directed behavior or reflects general suppressant effects on motivated behavior, BD1047 was tested also on reinstatement induced by stimuli conditioned to a natural reward, sweetened condensed milk (SCM). Additionally, because sigma(1) receptors have been implicated also in processes linked to the acute reinforcing actions of cocaine, tests of the effects of BD1047 on cocaine self-administration-including a comparison with the sigma(1) antagonist effects on SCM self-administration-were conducted as well. Cocaine self-administering male Wistar rats were trained to associate a discriminative stimulus (S(D)) with the availability of cocaine or SCM, and then subjected to reinstatement tests following extinction of cocaine or SCM-reinforced behavior. BD1047 (1-30 mg/kg) reversed response reinstatement induced by the cocaine S(D) at 20 and 30 mg/kg but did not modify SCM S(D)-induced responding at all but the highest 30 mg dose, at which responding was reversed to extinction levels. BD1047 did not modify responding reinforced directly by SCM or cocaine. The findings support a role for sigma(1) receptors in regulating conditioned responses to cocaine-related contextual stimuli and identify this receptor as a potential treatment target for the prevention of craving and relapse.

Biodistribution, pharmacokinetics and microSPECT/CT imaging of 188Re-bMEDA-liposome in a C26 murine colon carcinoma solid tumor animal model

Nanoliposomes are useful carriers in drug delivery. Radiolabeled nanoliposomes have potential applications in radiotherapy and diagnostic imaging. In this study, the biodistribution and pharmacokinetics of 188Re-BMEDA-labelled pegylated liposomes (RBLPL) and unencapsulated 188Re-BMEDA administered by the i.v. route in murine C26-colon tumour-bearing mice were investigated. MicroSPECT/CT images were performed to evaluate the distribution and tumor targeting of RBLPL in mice. For the biodistribution study, the highest uptake of liposome in tumors was 3.62% +/- 0.73% at 24 h after RBLPL administration, and the tumor to muscle ratio of RBLPL was 7.1-fold higher than that of 188Re-BMEDA. With image analysis, the highest SUV in tumor was 2.81 +/- 0.26 at 24 h after injection of RBLPL. The Pearson correlation analysis showed a positive correlation of tumor targeting or uptake of RBLPL between biodistribution and microSPECT semi-quantification imaging analysis (r = 0.633). The results of the pharmacokinetics revealed that the area under the tissue concentration-time curve (AUC) of RBLPL was 4.7-fold higher than that of unencapsulated 188Re-BMEDA. These results suggested the potential benefit and advantage of 188Re-labeled nanoliposomes for imaging and treatment of malignant diseases.

Protective effects of the sigma agonist Pre-084 in the rat retina

AIM

With the rationale that amyloid beta (AB) is toxic to the retina, we here assessed the role of TRAIL, a mediator of AB toxicity and related signal transduction, in a rat model. We also attempted to demonstrate possible protective effects of sigma 1 receptor agonists in these processes.

METHODS

AB and the sigma 1 receptor agonist Pre-084 were injected intravitreally in the anaesthetised rat. In additional experiments, the sigma 1 receptor antagonist BD1047 was administered to assess specificity of the effects of Pre-084. Western blot analysis was performed on retinas to evaluate the expression of TRAIL and TRAIL receptors in the retina, as well as of Bax and phosphorylated JNK following the different treatments. Lactic dehydrogenase (LDH) levels were measured as a cytotoxicity marker.

RESULTS

All TRAIL receptors were expressed in rat retinas. Intravitreal injection of AB in rat eyes induced overexpression of TRAIL and the proapoptotic protein Bax, as well as phosphorylation of JNK. All these effects of AB were abrogated by pretreatment with the sigma(1) receptor agonist Pre-084.

CONCLUSIONS

It is likely that TRAIL is a mediator of AB effects on the retina. In light of their specific inhibitory effects upon TRAIL expression, it is plausible to hypothesise that sigma(1) receptor agonists could represent potential pharmacological tools for restraining AB related retinal damage.

Conjugates of poly(DL-lactic acid) with ethylenediamino or diethylenetriamino bridged bis(beta-cyclodextrin)s and their nanoparticles as protein delivery systems

Some biodegradable amphiphilic copolymers were synthesized by conjugating poly(DL-lactic acid) (PLA) onto ethylenediamino or diethylenetriamino bridged bis(beta-cyclodextrin)s (bis-CDs). Double emulsion (DE) and nanoprecipitation (NP) methods were used to fabricate the nanoparticles of these copolymers entrapping bovine serum albumin (BSA) as a model protein. Effects of the experimental parameters, such as copolymer composition, BSA concentration, copolymer concentration and poly(vinyl alcohol) concentration, on particular size and encapsulation efficiency (EE) were investigated. Their EE to BSA could reach 83.5% at an optimized condition owing to the cooperative binding effect of the CD moiety with BSA. The core-corona structure of copolymer micelles fabricated from the nanoprecipitation was studied on the basis of 1H NMR and other measurements at various temperatures. The results showed that the core-corona structure kept stable below 50 degrees C (lower than Tg). And increase of the micelle association number occurred above the Tg because the size of the NPs became larger and proton signals of the liquid-like PLA cores could be observed in 1H NMR in D2O at 60 degrees C. The release profiles of NPs showed a burst effect followed by a continuous release. Sodium dodecyl sulfate polyacrylamide gel electrophoresis, circular dichroic and fluorescence spectra were further used to identify the stability of BSA released from the NPs. The nanoparticles from the conjugates have a promising potential in nasal delivery system.

Amphiphilic block copolymers promote gene delivery in vivo to pathological skeletal muscles

We reported that amphiphilic block copolymers hold promise as nonviral vectors for the delivery of plasmid DNA, ranging from 4.7 to 6.2 kb, to healthy muscle for the production of local or secreted proteins. To evaluate the efficiency of these vectors to deliver large plasmid DNA molecules to pathological muscles, plasmid DNAs of various lengths were complexed with Lutrol or poloxamine 304 and injected intramuscularly into dystrophic muscles. Lutrol-DNA and poloxamine 304-DNA complexes promoted gene transfer into muscles of the naturally occurring mouse model for DMD (mdx) in a dose- and plasmid DNA size-dependent manner. For small plasmid DNAs encoding reporter genes, this improvement over naked DNA was smaller in mdx than in the wild-type control strain. By contrast, Lutrol enabled us to deliver the large plasmid (16.1 kb) encoding the rod-deleted dystrophin in mdx mouse muscle, whereas the same amount of naked DNA did not lead to dystrophin expression, under the same experimental conditions. Lutrol-treated mdx mice showed the production of dystrophin in large numbers of muscle fibers. More importantly, we also found that expressing dystrophin with Lutrol led to restoration of the dystrophin-associated protein complex. Thus, we conclude that block copolymers constitute a novel class of vectors for the delivery of large plasmid DNA not only to healthy muscles but also to pathological muscle tissues.

Synthesis of Novel Biodegradable Cationic Polymer: N,N-Diethylethylenediamine Polyurethane as a Gene Carrier

A new cationic polymer, N,N-diethylethylenediamine-polyurethane (DEDA-PU), bearing tertiary amines in the backbone and side chains, was synthesized and used as a nonviral vector for gene delivery. The DEDA-PU readily self-assembled with the plasmid DNA (pCMV-betagal) in water and buffer at physiological pH, as determined by agarose gel retardation, dynamic light scattering, zeta potential, atomic force microscopy (AFM), and restriction endonuclease protection assays. The results revealed that DEDA-PU was able to bind with plasmid DNA, yielding positively charged complexes with a size around 100 nm at a DEDA-PU/DNA ratio of 50/1 (w/w). The DEDA-PU/DNA complexes were able to transfect HEK 293 cells in vitro with an efficiency comparable to a well-known gene carrier [poly(2-dimethylaminoethyl methacrylate), PDMAEMA]. The cytotoxicity of DEDA-PU was substantially lower than PDMAEMA. The degradation studies indicated that DEDA-PU degrades hydrolytically in 20 mM HEPES buffer at pH 7.4 with a half-life of approximately 60 h. This study shows that DEDA-PU holds promise as biodegradable polycations for gene delivery and is interesting candidate for further study.

Use of a topical disinfectant as part of a hoof care programme for horses with diseases of the hoof capsule

Twenty-three horses with persistent hoof horn defects were treated topically with a hoof disinfectant as part of a hoof care programme for a year. The active ingredients of the disinfectant were a poloaximer-iodine complex, ethylenediamine dihydriodide, isopropyl alcohol and propylene glycol. Hoof trimmings were taken at the start of the study and every six weeks, and examined by scanning and transmission electron microscopy. At the beginning of the study all the horn samples contained large numbers of bacteria, and samples from eight of the horses also had fungal hyphae intermingled with the bacteria. After the application of the hoof disinfectant and adjustments to their diet, there were rapid improvements in the gross appearance of the feet of all the horses; some of them improved within two to three weeks and by 12 weeks the horn quality of all the horses had greatly improved.

Zinc transformations in acidic soil and zinc efficiency on maize by adding six organic zinc complexes

Experiments under laboratory and greenhouse conditions were conducted to study the response of maize (Zea mays L.) to Zn fertilizer applications (Zn-phenolate, Zn-EDDHA, Zn-EDTA, Zn-lignosulfonate, Zn-polyflavonoid, and Zn-heptagluconate) in an Aquic Haploxeralf soil. The application of Zn complexes significantly increased Zn uptake by the plant compared with that in the control soil. The highest enhancements were obtained in soil treated with Zn-EDTA, Zn-lignosulfonate, and Zn-EDDHA. The highest percentages of Zn taken up by the plants occurred when 20 mg x kg(-1) Zn was applied as Zn-EDTA fertilizer and 10 mg x kg(-1) as Zn-lignosulfonate fertilizer. In the greenhouse experiment, Zn speciation in soil after harvesting showed that almost all Zn was found in the residual fraction followed by metal in the water-soluble plus exchangeable fraction and metal bound to organic matter. The most effective fertilizers maintaining Zn in the most labile fractions were Zn-phenolate, Zn-EDTA, and Zn-lignosulfonate. Conversely, in the incubation experiment, only a small percentage of Zn was found in the water-soluble plus exchangeable fraction and no differences in the Zn distribution were observed between the different fertilizer treatments. The micronutrient content in maize was positively correlated with the water-soluble plus exchangeable Zn as well as with the available Zn determined by the diethylenetriaminepentaacetic acid and Mehlich-3 methods, in the greenhouse experiment. Results of this study showed that the incubation experiment in acidic soil is not a suitable tool to establish the different effectiveness of Zn chelates in plants.

Lifespan extension and rescue of spongiform encephalopathy in superoxide dismutase 2 nullizygous mice treated with superoxide dismutase-catalase mimetics

Superoxide is produced as a result of normal energy metabolism within the mitochondria and is scavenged by the mitochondrial form of superoxide dismutase (sod2). Mice with inactivated SOD2 (sod2 nullizygous mice) die prematurely, exhibiting several metabolic and mitochondrial defects and severe tissue pathologies, including a lethal spongiform neurodegenerative disorder (Li et al., 1995; Melov et al., 1998, 1999). We show that treatment of sod2 nullizygous mice with synthetic superoxide dismutase (SOD)-catalase mimetics extends their lifespan by threefold, rescues the spongiform encephalopathy, and attenuates mitochondrial defects. This class of antioxidant compounds has been shown previously to extend lifespan in the nematode Caenorhabditis elegans (Melov et al., 2000). These new findings in mice suggest novel therapeutic approaches to neurodegenerative diseases associated with oxidative stress such as Friedreich ataxia, spongiform encephalopathies, and Alzheimer's and Parkinson's diseases, in which chronic oxidative damage to the brain has been implicated.

Involvement of the sigma receptor in passive-avoidance learning in the day-old chick during the second wave of neuronal activity

The specific sigma-receptor agonist (+)-SKF 10047 and antagonist BD 1047 were used to investigate whether this receptor was involved in passive-avoidance training in the day-old chick. We found 300 microM (+)-SKF 10047 to be amnesic when injected into the lobus parolfactorius 5 h after training (p < .01). Higher or lower concentrations of (+)-SKF 10047 did not disrupt memory formation. The amnesia produced by the efficacious dose of (+)-SKF 10047 was reversed by the specific antagonist, BD 1047. It is suggested that the sigma-receptor may exert its effect on passive-avoidance memory consolidation during the later stages of long-term memory formation by modulation of memory-related neurotransmission.

Drug delivery in poly(lactide-co-glycolide) nanoparticles surface modified with poloxamer 407 and poloxamine 908: in vitro characterisation and in vivo evaluation

Poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles of 150-nm mean size were produced by an interfacial deposition method. The polar model drug Rose Bengal was successfully loaded into the nanoparticles during production and the surface of these particles was subsequently modified with poloxamer 407 and poloxamine 908 in order to create a steric stabilising layer of PEG on the surface. Drug loading was low (<1%) which can be attributed to the polar nature of the drug and the small size of the nanoparticles. Drug release was biphasic with 50% release measured within 30 min in serum. After intravenous injection in rats, the drug loaded nanoparticles substantially avoided capture by the Kupffer cells of the liver as compared to free drug. The half-life of Rose Bengal in the blood stream when administered in the nanoparticles was greatly extended with approximately 30% remaining after 1 h as compared to only 8% of Rose Bengal left 5 min after administration in solution. These surface modified nanoparticles would have potential as carriers for drugs to specific sites within the body or for slow release of drug within the circulation.

Re-establishing the long circulatory behaviour of poloxamine-coated particles after repeated intravenous administration: applications in cancer drug delivery and imaging

In accordance with earlier observations, a single intravenous injection of long circulatory poloxamine-908-coated polystyrene particles to rats dramatically affected the circulation half-life and body distribution of a second dose when administered 10 days later. Both liver and spleen macrophages recognised and cleared from the blood the majority of the second dose of poloxamine-908-coated particles. The second dose of poloxamine-908-coated particles, however, regained their long circulatory behaviour when administered 1-3 h after a bolus intravenous injection of 30 mg free poloxamine-908 or poloxamer-407 (in saline)/150 g body weight. When the interval between free copolymer and particle administration was increased to 24 h then macrophage-rich organs were able to extract poloxamine-coated beads from the blood. In contrast to poloxamine-908 and poloxamer-407, prior administration of poloxamer-188 and polyethyleneglycol-20000 also failed to restore the long circulatory behaviour of the second dose of poloxamine-908-coated particles. These observations are of interest in experimental drug delivery, particularly in experimental cancer therapy (diagnostic imaging and drug delivery), involving multiple injections of poloxamine-based long circulating nanosized vehicles.

Antitussive action of antihistamines is independent of sedative and ventilation activity in the guinea pig

We studied the oral actions of antihistamines from six chemical classes, namely: the ethanolamines (ENA, diphenhydramine and clemastine); ethylenediamines (EDA, pyrilamine and tripelennamine); piperidines (PPD, terfenadine and astemizole); piperazines (PPZ, hydroxyzine and cetirizine); phenothiazines (PTZ, promethazine), and the alkylamines (ALA, chlorpheniramine and bromopheniramine) on cough reflexes, pentobarbital-induced sedation and minute ventilation in the conscious guinea pig. Antihistamines of the ENA class had minimal effects on capsaicin-induced cough although both diphenhydramine (30 and 100 mg/kg p.o.) and clemastine (30 and 100 mg/kg p.o.) increased sedation time (ST). The PPZ class demonstrated both antitussive and sedating activity. The minimum effective oral antitussive dose (MED) of cetirizine and hydroxyzine was 30 and 10 mg/kg, respectively. The EDA did not exhibit antitussive activity. Tripelennamine (10, 30 and 100 mg/kg p.o.) but not pyrilamine enhanced ST. The MED for the PTZ, promethazine, was 10 mg/kg, and at 100 mg/kg promethazine increased ST. The ALA group displayed antitussive activity but only chlorpheniramine (10 mg/kg p. o.) had any effects on ST. The MED for chlorpheniramine and bromopheniramine was 3 and 10 mg/kg p.o., respectively. The PPD antihistamines, namely terfenadine and astemizole, inhibited cough (MED 30 and 10 mg/kg p.o.) without sedative effects. Of the antihistamines tested only promethazine (100 mg/kg p.o.) depressed ventilation responses; however, this dose of promethazine was associated with adverse behavioral effects. The present findings indicate that the antitussive actions of antihistamines are not directly related to histamine H1-receptor blockade because several antihistamines did not antagonize capsaicin-induced cough. In addition, the antitussive actions of antihistamines are independent of their sedative or ventilation effects.

Diverse effects of metal chelating agents on the neuronal cytotoxicity of zinc in the hippocampus

Abnormal metabolism of metal ions such as zinc may contribute to neuropathology. Complexing zinc could reduce this pathology. Thus, to examine the effectiveness of metal chelating agents in vivo, a model system was used. This involved determining the ability of chelating agents to prevent neuronal death caused by zinc chloride injected into the rat hippocampus. Significant protection against zinc toxicity was obtained with pyrithione, inositol hexakisphosphate, ethylenediamine tetraacetate (EDTA) and N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN). The affinity of these agents for zinc varied between 106 M-1 and 1018 M-1. Thus, the affinity for zinc within this range does not appear to be a major factor affecting the ability of chelators to provide neuroprotection. While almost complete protection was found with EDTA and TPEN given simultaneously with zinc chloride, poor protection was obtained if TPEN was given before or after zinc chloride. Other agents either did not protect against zinc-induced neuronal death (zincon), or exacerbated zinc toxicity (BTC-5N and about 40% of rats injected with a combination of zinc chloride and diethylenetriamine pentaacetate [DTPA]). Rats showing increased damage after zinc plus BTC-5N or DTPA suffered wet dog-like shakes (WDS), suggesting that these zinc chelate complexes can induce seizures resulting in seizure-related damage. In contrast, in the 60% of rats treated with zinc chloride and DTPA that had no WDS, there was about an 80% reduction in the size of the zinc-induced lesion. The ability of chelators to cross cell membranes was examined by determining whether Timm's staining for vesicular zinc was reduced following the injection of a chelator into the hippocampus. TPEN and pyrithione reduced Timm's staining for zinc. However, cell permeability was not necessary for a chelator to protect against zinc toxicity.

Activation of the mononuclear phagocyte system by poloxamine 908: its implications for targeted drug delivery

PURPOSE

To investigate the effect of poloxamine 908 on the MPS activity and the importance of its mode of presentation to the immune system.

METHODS

Solutions of endotoxin free poloxamine 908 were injected daily intravenously to rats, and the effect on the degree of sequestration by the liver of I125 labelled, poloxamine 908-coated 60 nm polystyrene particles was investigated by studying effect of dosing regimen(s) and assessment of opsonic activity.

RESULTS

After 3 or 4 days repeated dosing with poloxamine 908 (0.7 mg) in solution, the poloxamine 908-coated polystyrene particles (60 nm) were rapidly cleared from the circulation. The increase sequestration of the particles by the liver lasted for more than 7 days after last dosing with the poloxamine 908 solution. In subsequent studies, it was found that a single dose of poloxamine 908 (0.7 mg) in solution was sufficient to activate the MPS 4 days after the injection. The increased uptake was found not be mediated by a serum component, nor was it due to proliferation of the Kupffer cells in the liver.

CONCLUSIONS

The results provide evidence that a solution of endotoxin-free poloxamine 908 activates the MPS so that 4 days after injection otherwise long-term circulating poloxamine 908-coated particles are sequestered by the liver. This finding has implications for use of such coated systems in therapeutic situations.

Long circulating biodegradable poly(phosphazene) nanoparticles surface modified with poly(phosphazene)-poly(ethylene oxide) copolymer

The biodistribution of biodegradable poly(organo phosphazene) nanoparticles surface modified by adsorption of a novel poly(organo phosphazene)-poly(ethylene oxide) copolymer with a 5000 M(W) PEO chain (PF-PEO[5000]), following intravenous administration in rats and rabbits, is described. The data are compared to the biodistribution of poly(organo phosphazene) and poly(lactide-co-glycolide) nanoparticles coated with a tetrafunctional copolymer of poly(ethylene oxide)-poly(propylene oxide) ethylenediamine, commercially available as Poloxamine 908. This copolymer has a PEO chain of the same size as the poly(organo phosphazene)-PEO derivative used. The results in the rat model reveal that poly(organo phosphazene) nanoparticles with a Poloxamine 908 coating were mainly captured by the liver, although a retardation in clearance from the systemic circulation was seen. In contrast, the poly(organo phosphazene) nanoparticles coated with PF-PEO(5000) showed a prolonged blood circulating profile, with only a small amount of the nanoparticles sequestered by the liver. This indicates the importance of the nature of both the anchoring group and the particle surface on the biological performances of the system. Study of the biodistribution of the PF-PEO(5000)-coated poly(organo phosphazene) nanoparticles in the rabbit model also indicated a prolonged systemic circulation lifetime and reduced liver uptake, whereby a significant amount of the administered nanoparticles was targeted to the bone marrow.

Prolonging the circulation time and modifying the body distribution of intravenously injected polystyrene nanospheres by prior intravenous administration of poloxamine-908. A 'hepatic-blockade' event or manipulation of nanosphere surface in vivo?

Intravenously injected uncoated small (60 nm) and large (250 nm) size model polystyrene particles (which are cleared rapidly from the blood by macrophages of the reticuloendothelial system) can be converted to long-circulatory and splenotropic particles in vivo, respectively, if such particles are injected shortly (up to 3 h) after an appropriate dose of the block polymer non-ionic surfactant, poloxamine-908. Evidence indicates that small and large size polystyrene beads can acquire a coating of poloxamine-908 and/or poloxamine-protein complexes in vivo. The adsorption of such complexes on to the bead surface could explain their altered body distribution since small and large size polystyrene beads that were precoated with poloxamine-908 exhibit similar biodistribution following i.v. injection.

Subchronic administration of N-[2-(3,4-dichlorophenyl) ethyl]-N-methyl-2-(dimethylamino) ethylamine (BD1047) alters sigma 1 receptor binding

BD1047 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine) is known to bind with high affinity and selectivity to sigma sites in vitro. In prior in vivo studies, it has been shown to attenuate the dystonic postures and orofacial dyskinesias that are produced by sigma receptor ligands, including the neuroleptic haloperidol. Since abnormal movements, such as dystonic postures and orofacial dyskinesias, are side effects that are associated with many sigma-active neuroleptics, compounds such as BD1047 may have therapeutic potential for preventing and treating these unwanted movements. A possible limitation to the therapeutic potential of BD1047, however, is that at least in cell culture and albeit weak, it can be cytotoxic. Therefore, the present study analyzed the possible neurotoxic effects of in vivo subchronic intracerebroventricular infusion of BD1047 (10 nmol/h) or artificial cerebrospinal fluid (CSF) into rat brains using osmotic minipumps for 7 or 14 days. Following a 24 h wash-out period, the animals were killed, the brains removed, and P2 membranes prepared. Membranes from rats treated for 7 or 14 days with BD1047 showed a marked decrease in [3H](+)-pentazocine binding as compared to membranes from CSF-treated animals, suggesting a loss of sigma 1 receptor binding. Histological examination of brain sections processed for Nissl stains and glial fibrillary acidic protein (GFAP) immunohistochemistry excluded the possibility of a cytotoxically induced down-regulation, suggesting possible receptor internalization or desensitization mediated via sigma 1 sites. Under the conditions used in our study, BD1047 does not appear to be neurotoxic, and the data, when taken together with other studies, suggest that BD1047 acts as a partial agonist at sigma sites.

In vitro and in vivo evaluation of potential aluminum chelators

The potential for aluminium (Al) chelation by different compounds was determined using 2 in vitro techniques. The formation of stable complexes with Al in an aqueous solution was evaluated using pulse polarography. This technique allowed the influence of temperature and calcium (Ca) to be studied for each compound. Certain compounds (EDDHA, HAES, citric acid and HBED) showed great chelation in the absence of Ca2+ at a temperature of 37 +/- 1 C. An ultrafiltration technique combined with Al determination by atomic emission spectroscopy allowed the efficiency of different substances to complex Al that were previously bound to serum proteins to be estimated. The kinetics of chelation and minimum efficient concentration have been determined for all products studied. EDDHA had chelation potential similar to DFO. The real efficacies of the compounds were studied in vivo to compare the effectiveness of repeated administrations of the best chelating agents (EDDHA, DFO, HAES and tartaric acid) on the distribution and excretion of Al after repeated i.p. administrations to rats. Intraperitoneal EDDHA significantly increased urinary metal (Al, Ca, Cu, Fe and Zn) excretion. These excretions may be correlated to a renal toxic potential property.

Disturbances in rat smooth-muscle induced by a substance with fungicide action

The fungicide substance QAS [N,N,N',N'-tetramethyl-N,N'-di(8,15-dichloropentadeca-5,10- dien)ethylenediamine methylsulphate] has a biphasic effect on the spontaneous electrical and mechanical activity of smooth-muscle samples of rat corpus and guinea-pig taenia coli. During the first phase of QAS application membrane depolarization and increased spontaneous spike frequency were recorded. The tone of the preparations (resting tone) increased transiently. Calcium ion-entry blockers did not affect the contractile effect of QAS, but K(+)-channel blockers and some modulators of the second messenger system abolished or decreased it. During the second phase depolarization increased progressively, spike frequency decreased and the increase in resting tone recorded during the first phase was eliminated. The results reveal that the long-lasting depolarizing effect of QAS (in concentrations used for plant protection) probably inactivates the entry of Ca2+ into the smooth-muscle cells and disturbs Ca2+ homeostasis.

Enhanced hepatic clearance of intravenously administered sterically stabilized microspheres in zymosan-stimulated rats

The blood clearance and organ deposition of sterically stabilized (poloxamine-908 coated) polystyrene microspheres of two different sizes (60 and 220 nm in diameter) were compared in control and zymosan-stimulated rats 3 h after intravenous administration. Poloxamine coating dramatically decreased the uptake of 60-nm microspheres by organs of the reticuloendothelial system and, concomitantly, kept microspheres in the blood. Large poloxamine-coated microspheres (220 nm) initially remained in the blood, but eventually a large fraction of these microspheres was filtered by the spleen. Daily administration of zymosan produced a marked increase in the intravascular clearance of the large, but not the small, poloxamine-coated microspheres. The enhanced intravascular clearance of large poloxamine-coated microspheres in zymosan-treated rats was the result of hepatic sequestration. On the other hand, the splenic filtration of these microspheres was depressed by 225% below the control values, despite the dramatic increase in spleen size of zymosan-treated rats. Preincubation of large poloxamine-coated microspheres in serum derived from both the control and zymosan-treated animals suggested that the enhanced hepatic uptake of large sterically stabilized microspheres following zymosan stimulation was not the result of "specific opsonization" processes. Instead, the changes in the proliferative as well as the phagocytic response of Kupffer cells appeared to be responsible for these observations. The preferred hepatic uptake of large poloxamine-coated microspheres, as opposed to smaller particles, is suggested to be due to differences in surface characteristics and the properties of microspheres. These may include differences in polymer density and the surface conformation of the polyoxyethylene segments of the polymer in the biological environment and the way they interact with both plasma components and the macrophage surface. These observations could be of importance in the use of sterically stabilized drug carriers for delivery of therapeutic agents to sites other than the reticuloendothelial system in clinical conditions associated with globally or regionally enhanced reticuloendothelial activity.

The antitumor activity of the platinum complex D-17872 is associated with tumor cell differentiation

The novel cisplatin analogue D-17872 was studied for its anticancer activity using in vivo and in vitro preclinical models. The compound at the sublethal dose of 215 mg/kg (ca. 50% of the approximate LD50) induced no nephrotoxic effect strong enough to increase the blood urea level in rats. It had good in vivo antitumor efficacy against murine P388 (max. ILS: D-17872 132%, cisplatin 55%) and L1210 leukemia (max. ILS: D-17872 43%, cisplatin 38%), L5222 leukemia of the rat (max. ILS: D-17872 163%, cisplatin 163%) and murine B16 melanoma. Activity against P388 leukemia substantially exceeded that of cisplatin. Moreover, the M5076 reticulum cell sarcoma implanted into the subrenal capsule and the DMBA-induced mammary tumor of the rat were inhibited by D-17872 to a greater extent than by cisplatin (min. T/C: D-17872 -3%, cisplatin 11%). Using clonogenic microassays, D-17872 was active in vitro against a variety of human and rodent tumor cell lines, albeit at higher concentrations than cisplatin (IC50 values: D-17872 2.6-12.7 mumol/l, cisplatin 0.13-0.42 mumol/l). Apart from its cytotoxic action it was able to induce in vitro differentiation of the human HL-60 and K562 and of the murine M1-T22 cell lines, while cisplatin induced differentiation only in the HL-60 cell line. Thus D-17872 exhibited a pharmacological and toxicological profile different from that of the parent compound. The results suggest that induction of differentiation contributes to the antineoplastic efficacy of this novel cisplatin derivative.

Respiratory burst in peritoneal exudate cells in response to a modified tuftsin

Intraperitoneal administration of tuftsin-M [Thr-Lys-Pro-Arg-NH-(CH2)2-NH-CO-C15H31] to Balb/C mice has been shown to induce a respiratory burst in the peritoneal exudate cells. The macrophages exhibited enhanced levels of O2-, H2O2, NADPH oxidase and myeloperoxidase, but the activities of superoxide dismutase, catalase and glutathione peroxidase remained virtually unchanged. The magnitude of the oxidative burst depended directly on the dose of tuftsin-M; higher activity was observed at higher doses of the peptide. Tuftsin-M enhanced the generation of both O2- and H2O2 under in vitro conditions, as did phorbol myristate acetate. These results suggest that tuftsin-M could enhance non-specific defence against infections by activating the macrophages.

Immunomodulatory ionophore copolymers, T150R1 and T130R2, induce corticotropin from anterior pituitary cells

T150R1 is a synthetic copolymer with Na+ ionophore activity. We demonstrated previously that T150R1, when injected into mice, produces rapid thymic involution with depletion of cortical thymocytes. Elevated serum ACTH and corticosterone levels, as well as abrogation of the effects of T150R1 on the thymus by adrenalectomy and hypophysectomy, suggested a pituitary-mediated mechanism. In this work, we investigated the ability of T150R1, and of the related ionophore copolymer T130R2, to stimulate ACTH in vitro from the mouse anterior pituitary cell line AtT-20. Copolymer-induced ACTH release was dose-, time-, and temperature-dependent. Hormone induction peaked at 30 degrees C for T150R1 and 37 degrees C for T130R2. The temperature dependence of ACTH release paralleled that of ionophore activity measured in red blood cells, providing evidence that the ability to induce ACTH is related to the ionophore property of the copolymers. Peak ionophore activity and hormonal release occurred at the temperatures when the copolymers form partially soluble complexes which interact optimally with cell membranes. Cotreatment with exogenous phospholipase C inhibited the effects of T150R1, which suggests that the enzyme either blocks the insertion of T150R1 into the cell membrane or that the phospholipase C-induced increase in intracellular calcium inhibits the ionophore activity of T150R1. These data support an ionophore mechanism for copolymer-induced ACTH release in which changes in the physicochemical structure of the copolymers may affect their interaction with cell membranes. The data also suggest that direct stimulation of pituitary ACTH accounts for at least some of the in vivo immunomodulatory effects of T150R1.

Aminophylline hypersensitivity apparently due to ethylenediamine

Asthmatic patients receive multiple drugs as part of their treatment program. When a subsequent allergic reaction occurs, the ethylenediamine component of aminophylline is usually not suspected as the etiologic agent. We present a case of ethylenediamine-induced delayed hypersensitivity reaction in a 46-year-old woman who received parenteral aminophylline for an acute asthma exacerbation. Patch testing for ethylenediamine was positive.

Value of the cutaneous basophil hypersensitivity (CBH) response for distinguishing weak contact sensitization from irritation reactions in the guinea pig

Numerous studies of the histology of allergic contact dermatitis reactions to potent allergens in guinea pigs and humans have indicated that there is significant tissue infiltration with basophilic leukocytes. In this study we determined whether this histologic finding could be of value in distinguishing weak sensitization reactions from primary irritation, thereby aiding in the predictive identification of weak or moderate contact allergens. Guinea pigs were sensitized by the Buehler test method. Skin reactions were graded 24, 48, and 72 h post-challenge with duplicate patch sites biopsied at the 24- or 72-h grading timepoints. The biopsies were fixed, embedded in glycol methacrylate, thin sectioned, and Giemsa stained. The number of basophils per 400 leukocytes were counted along the upper dermis just below the dermal/epidermal junction. Challenge patch sites from animals sensitized to a relatively low dose of the strong contact allergen, oxazolone, were compared with patch sites from animals challenged only with a strong irritant, sodium lauryl sulfate (SLS). Compared to normal skin (7.5 +/- 1.0 basophils/400 leukocytes +/- SEM) only the oxazolone patch sites showed significant basophil infiltration (36.8 +/- 6.5), despite the fact that the skin reactions to the low oxazolone challenge dose were relatively weak. SLS patch sites showed no basophil infiltration above normal skin levels (4.8 +/- 0.9). Subsequent blinded studies compared weak/moderate presumptive sensitization reactions (as defined by accepted visual skin grading criteria) to various chemicals (citronellal, vanillin, cinnamic aldehyde, and ethylenediamine) to primary irritation reactions to the same chemicals. In each case, low-challenge-dose sensitization sites on previously treated (induced) animals showed mean basophil infiltration (range, 11.9-69.2 basophils/400 leukocytes) significantly greater than higher-dose irritant reactions (range, 1.6-13.3). The range for normal skin was 0.2-10.2 and the range for strong patch reactions to higher concentrations of oxazolone was 59.8-209.3. These data strongly indicate that light-microscopic quantitation of the CBH response can be used to distinguish relatively weak to moderate contact sensitization reactions from primary irritation reactions to the same chemicals.

Effects of elevated iodine in milk replacer on calf performance

Calves were fed milk replacer containing .57, 10, 50, 100, or 200 ppm iodine (from ethylenediaminedihydroiodide) in DM, from 3 to 38 d of age, to estimate the minimum toxic concentration of iodine. Only the 200 ppm iodine intake reduced weight gains, DM intake, feed efficiency, and DM digestibility. At the 100 and 200 ppm iodine intakes, protein digestibility was reduced, and calves showed typical symptoms of iodine toxicity (nasal discharge, excessive tear and saliva formation, and coughing from tracheal congestion). Thyroid iodine increased with every elevation in iodine intake. Iodine in plasma, bile, and non-thyroid tissues started to increase at the 50 ppm intake and, except for muscle, tended to increase again at the 100 and 200 ppm intakes. Thus, the preruminant calf tolerated up to 50 ppm iodine in milk replacer DM for 5 wk postpartum. However, as iodine concentrations in plasma and nonthyroid tissues started to increase at 50 ppm iodine, an upper limit of 10 ppm would be more preferable.

Iodine in milk and meat of dairy cows fed different amounts of potassium iodide or ethylenediamine dihydroiodide

Relationships between I intake by lactating Holstein cows and iodine concentrations in milk and meat were investigated. Six treatment groups with seven cows assigned to each treatment were fed a basal diet containing .8 mg I/kg alone or supplemented with I at 1, 2, or 4 mg/kg in four 5-wk periods. Basal alone was fed in the first and third periods and the I supplement was potassium iodide in the second period and ethylenediamine dihydroiodide in the fourth period. Iodine concentrations in milk increased with each increase in dietary I from 205 ng/ml for basal periods to 404, 477, and 757 ng/ml when 1, 2, or 4 mg/kg I was fed as potassium iodide; and 467, 535, and 869 ng/ml when 1, 2, or 4 mg/kg I was fed as ethylenediamine dihydroiodide. Concentrations of I in skeletal muscle after the fourth period were not affected by 2 mg/kg I and only increased from 166 to 199 ng/g when supplemental I was 4 mg/kg. Moderate changes in dietary I are quickly reflected in milk I, but I in meat is relatively stable.

Serum distribution of iodine after oral administration of ethylenediamine dihydriodide in cattle

Serum concentrations of iodine were determined after cattle were given ethylenediamine dihydriodide (EDDI) orally at dosages ranging from 0.0 (placebo) to 0.77 mg/kg of body weight/day. The serum iodine concentration was correlated with the dosage of EDDI. A rate of 0.11 mg EDDI/kg/day was correlated with serum iodine concentrations (20 to 80 micrograms/dl) previously found to be effective in preventing foot rot in cattle. A linear dose-response curve that was generated could be helpful in predicting dosage of EDDI if the serum iodine concentration is known.