Sodium <Superscript>131</Superscript>i-mercaptododecaborate biodistribution in B-16 melanoma in mice

The biodistribution of sodium mercaptododecaborate labeled with radioactive iodine (¹³¹I-BSH) in melanoma B-16 and surrounding tissues in mice has been studied for administration by various methods including intraperitoneal, single and double intratumor injection, and introduction under tumor bed. It is shown that a high content of ¹³¹I-BSH in the tumor is reached in all cases. The maximum accumulation of the boron compound is observed 1 h after administration. In this case the ratio of radioactivities in melanoma B-16 and surrounding tissues in most animals was greater than 3. A study of ¹³¹I-BSH uptake in tumor cells showed that a considerably greater accumulation of the compound is observed 3 and 6 h after intraperitoneal administration in the intercellular space (65.3% and 63.0%, respectively) in comparison to the cellular content (34.7% and 37.0%, respectively). The levels of accumulation become identical in about 12 h after administration. Approximately equal uptake of the boron compound in the intercellular space and tumor cells was observed over the entire period of investigation (0.5–2 h) after a single intratumor administration of ¹³¹I-BSH. The results of this study suggest that the intratumor administration of boron compounds is promising for neutron capture therapy, especially in combination with neutron teletherapy.     

Effect of infrared radiation on the pharmacokinetics of 131I-mercaptododecaborate in animals with model tumors

The influence of local IR irradiation of the experimental melanoma B-16 zone on the distribution of sodium mercaptododecaborate labeled with radioactive iodine (¹³¹I-BSH) in mice was studied for two regimes of thermal treatment (before and after administration of the labeled compound). It was established that a considerable increase in the ¹³¹I-BSH content in the model tumor was reached in the case of IR irradiation performed 1 h after drug administration. Based on these data, IR radiation can be considered an effective modifier of ¹³¹I-BSH uptake in tumors, increasing the efficacy of boron-enhanced neutron capture therapy. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 39, No. 12, pp. 9–11, December, 2005.     

Distribution of radioactive iodine labeled sodium mercaptododecaborate <Emphasis Type="Italic">in vivo</Emphasis> in mice with melanoma B-16

The distribution of sodium mercaptododecaborate labeled with radioactive iodine (¹³¹I-BSH) in the organism of mice with melanoma B-16 was studied with the aid of a gamma camera. The ¹³¹I-BSH distribution in the whole organism coincides with that of its unlabeled analog. This result facilitates the solution of problems related to the planning and monitoring of boron neutron capture therapy. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 39, No. 10, pp. 8–11, October, 2005.     

Comparative analysis of pharmacokinetic characteristics of radiopharmaceuticals based on the monopotassium salt of 1-hydroxyethylidenediphosphonic acid labeled by <Superscript>99m</Superscript>T9c and <Superscript>188</Superscript>Re

Investigation of pharmacokinetic characteristics of the ^99mTc- and ¹⁸⁸Re-labeled monopotassium salt of 1-hydroxyethylidenediphosphonic acid (KHEDP) in rats showed that the level of accumulated activity at 5 min and 1 and 3 h after i.v. injection of ¹⁸⁸Re-KHEDP is higher in most organs and tissues than that after injection of ^99mTc-KHEDP. In the subsequent period (6 and 24 h), the specific activities in the majority of soft organs and tissues equalized due to greater elimination of ¹⁸⁸Re-KHEDP. The dynamics of labeled drug accumulation in bone tissues is characterized by a gradual increase in the activity concentration followed by its slow decrease. The maximum accumulation of ^99mTc-KHEDP in bone was achieved within 3 – 6 h whereas the activity of ¹⁸⁸Re-KHEDP was at a maximum 1 h after injection. The activity gradually decreases after reaching the maximum value. The rate of ^99mTc-KHEDP elimination from bone is slower than that for ¹⁸⁸Re-KHEDP. The ratios of the specific activity in organs and tissues upon i.v. injection of ^99mTc-KHEDP and ¹⁸⁸Re-KHEDP are illustrated more clearly by the coefficients of differential accumulation (CDA) of activity in bone (bone of femur, rib, skull, and spine) relative to soft organs and tissues. The dynamics of the change in these values is characterized by a gradual increase over 24 h after injection. The growth is more pronounced for ¹⁸⁸Re-KHEDP than for ^99mTc-KHEDP. These data show that the elimination of activity from bone upon injection of ¹⁸⁸Re-KHEDP is faster than that for ^99mTc-KHEDP. A comparative analysis of the CDA values allows the dynamics of drug accumulation and elimination rates from soft organs and tissues to be evaluated in comparison to bone. Using the CDA values, it is also possible to determine the optimum conditions for carrying out scintigraphy studies of the skeleton using a gamma camera. The results from the study of the pharmacokinetic characteristics of ^99mTc-KHEDP and ¹⁸⁸Re-KHEDP in rats showed that these complexes have similar structures and substantially different biological properties, as indicated by the substantial differences in their in vivo behavior upon i.v. injection.     

Injectable Hydrogels for Localized Chemotherapy and Radiotherapy in Brain Tumors

Overall survival of patients with newly diagnosed glioblastoma (GBM) remains dismal at 16 months with state-of-the-art treatment that includes surgical resection, radiation, and chemotherapy. GBM tumors are highly heterogeneous, and mechanisms for overcoming tumor resistance have not yet fully been elucidated. An injectable chitosan hydrogel capable of releasing chemotherapy (temozolomide [TMZ]) while retaining radioactive isotopes agents (iodine, [¹³¹I]) was used as a vehicle for localized radiation and chemotherapy, within the surgical cavity. Release from hydrogels loaded with TMZ or ¹³¹I was characterized in vitro and in vivo and their efficacy on tumor progression and survival on GBM tumors was also measured. The in vitro release of ¹³¹I was negligible over 42 days, whereas the TMZ was completely released over the first 48 h. ¹³¹I was completely retained in the tumor bed with negligible distribution in other tissues and that when delivered locally, the chemotherapy accumulated in the tumor at 10-fold higher concentrations than when delivered systemically. We found that the tumors were significantly decreased, and survival was improved in both treatment groups compared to the control group. Novel injectable chemo-radio-hydrogel implants may potentially improve the local control and overall outcome of aggressive, poor prognosis brain tumors.     

Radiolabeling of EGCG with <Superscript>131</Superscript>I and biodistribution in rats

Epigallocatechin gallate (EGCG), is the most abundant and widely studied catechin in green tea (Camellia sinensis Theaceae). The inhibitory effects of EGCG and green tea extract on carcinogenesis in various organs in rodents have now been demonstrated over the past decade. The aim of study was to label EGCG with I-131, to determinate its structure and to evaluate its biodistribution in Wistar rats. Radiolabeling was carried out by direct electrophilic iodination method (iodogen) and yield was determined by radio thin layer chromatography (RTLC). Radiolabelling yield is determined as 89 ± 1.0%. Besides, determination of structure of iodinated molecule, serum stability, and partition coefficient experiments was performed. The structure analysis of synthesized cold ¹²⁷I-EGCG complex was assessed with LC–MS–MS and ¹H-NMR. ¹H-NMR and LC–MS–MS results of iodinated EGCG (¹²⁷I-EGCG) show that oxidize iodine reacts electrophilic with aromatic ring. Serum stability results showed that in vitro stability of ¹³¹I-EGCG was quite high. It is observed that labeling percentage decreased 83 ± 2% at 24th, Partition coefficient results show that the partition coefficient of EGCG was calculated as theoretical partition coefficient = 2.04 ± 0.42 and the experimental partition coefficient of ¹³¹I-EGCG was found as 1.46 ± 0.2. The biodistribution data shown that the maximum uptake of the radioiodinated EGCG was seen in lung and pancreas at 30 min. The blocking assay results indicated that the uptake of ¹³¹I-EGCG in lung was not significantly change (0.25, 0.23, and 0.22%ID/g at 30, 60, and 150 min, respectively). Biodistribution data showed no significant uptake in a specific organ of the rat. Hence radiolabeled EGCG is seen in some organs (lung, liver, pancreas, kidney, etc.).     

Effects of gabapentin and pregabalin on K<Superscript>+</Superscript>-evoked <Superscript>3</Superscript>H-GABA and <Superscript>3</Superscript>H-glutamate release from human neocortical synaptosomes

One site of action of the anticonvulsant, analgesic, and anxiolytic drugs gabapentin and pregabalin is the α₂δ-subunit of voltage-sensitive Ca²⁺ channels (VSCC). We therefore analyzed the effects of gabapentin and pregabalin on K⁺-evoked release of ³H-γ-aminobutyric acid (GABA) and ³H-glutamate from superfused human neocortical synaptosomes. These neurotransmitters are released by Ca²⁺-dependent exocytosis and by Ca²⁺-independent uptake reversal. When a GABA transport inhibitor was present throughout superfusion to isolate exocytotic conditions, gabapentin and pregabalin (100 μM each) reduced K⁺-evoked ³H-GABA release by 39% and 47%, respectively. These effects were antagonized by the α₂δ-ligand l-isoleucine (1 μM) suggesting the α₂δ-subunit of terminal VSCC to mediate the reduction of exocytosis. Both drugs had no effect on exocytotic ³H-glutamate release and also failed to modulate the release of ³H-GABA and ³H-glutamate caused by reversed uptake in the absence of external Ca²⁺. Thus, an inhibition of glutamate release by gabapentin and pregabalin as main anticonvulsant principle is not supported by our experiments. An anticonvulsant mode of action of both drugs may be the reduction of a proconvulsant exocytotic GABA release.     

Examination of the structure of agaricinic acid using <Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR spectroscopy

Agaricinic acid was extracted from the carpophore of Fomitopsis officinalis (Vill. Bond. et Sing). Its structure was established by ¹H and ¹³C NMR spectroscopy and comparison to a standard sample (Sigma—Aldrich). The extraction was carried out using ethanol. The obtained extract was evaporated, cooled (−5°C), and purified by ether. The structure of unbranched alkyl radicals was determined using their proton spectrum. The ¹³C NMR spectrum and two-dimensional {¹³C,¹H} correlation diagram showed the presence of a hydroxyl (second quaternary C atom) and three types of carboxy groups (first, second, and third C atoms). The spectrum of the extracted sample is identical to that of the standard sample of agaricinic acid.     

Effects of trimebutine maleate on colonic motility through Ca<Superscript>2+</Superscript>-activated K<Superscript>+</Superscript> channels and L-type Ca<Superscript>2+</Superscript> channels

The effects of trimebutine maleate (TM) on spontaneous contractions of colonic longitudinal muscle were investigated in guinea pigs. The contractile responses of smooth muscle strips were recorded by an isometric force transducer. Membrane and action potentials were detected by an intracellular microelectrode technique. The whole-cell patch clamp recording technique was used to record the changes in large conductance Ca²⁺-activated K⁺ (BK_ca) and L-type Ca²⁺ currents in colonic smooth muscle cells. At high concentrations (30, 100, and 300 μM), TM inhibited the amplitude of spontaneous contractions. At low concentrations (1 and 10 μM), TM attenuated the frequency and tone of smooth muscle strips, whereas TM had no influence on the amplitude of spontaneous contractions. TM depolarized the membrane potentials, but decreased the amplitude and frequency of action potentials at high concentrations. TM inhibited BK_ca and L-type Ca²⁺ currents in a dose-dependent manner. In the presence of the BK_ca channel opener, NS1619, TM also inhibited BK_ca currents. Bayk8644, a L-type Ca²⁺ channel opener, increased L-type Ca²⁺ currents. This augmentation was also attenuated by TM. These results suggest that TM attenuates intestinal motility through inhibition of L-type Ca²⁺ currents, and depolarizes membrane potentials by reducing BK_ca currents. Thus, TM may be a multiple-ion channel regulator in the gastrointestinal tract.     

Differential modulation of K<Superscript>+</Superscript>-evoked <Superscript>3</Superscript>H-neurotransmitter release from human neocortex by gabapentin and pregabalin

Anticonvulsant, analgesic, and anxiolytic effects have been observed both in preclinical and clinical studies with gabapentin (GBP) and pregabalin (PGB). These drugs appear to act by binding to the α₂δ subunit of voltage-sensitive Ca²⁺ channels (VSCC), resulting in the inhibition of neurotransmitter release. In this study, we examined the effects of GBP and PGB (mostly 100 μM, corresponding to relatively high preclinical/clinical plasma levels) on the release of neurotransmitters in human neocortical slices. These slices were prelabeled with ³H-dopamine (³H-DA), ³H-choline (to release ³H-acetylcholine (³H-ACh)), ³H-noradrenaline (³H-NA), and ³H-serotonin (³H-5-HT), and stimulated twice in superfusion experiments by elevation of extracellular K⁺ in the presence and absence of GBP and PGB. The α₂δ ligands produced significant inhibitions of K⁺-evoked ³H-ACh, ³H-NA, and ³H-5-HT release between 22% and 56% without affecting ³H-DA release. Neither drug reduced ³H-NA release in the presence of l-isoleucine, a putative α₂δ antagonist. Interestingly, this antagonism did not occur using the enantiomer, d-isoleucine. These results suggest that GBP and PGB are not general inhibitors of VSCC and neurotransmitter release. Such α₂δ ligands appear to be selective modulators of the release of certain, but not all, neurotransmitters. This differential modulation of neurotransmission presumably contributes to their clinical profile. A preliminary report of this work was presented at the German Society for Experimental and Clinical Pharmacology and Toxicology, Mainz, Germany, March 13–15, 2007 (Brawek et al. 2007).     

<Superscript>1</Superscript>H NMR metabolomics of earthworm responses to polychlorinated biphenyl (PCB) exposure in soil

¹H NMR-based metabolomics was used to examine the metabolic profile of D₂O-buffer extracted tissues of Eisenia fetida earthworms exposed for 2 days to an artificial soil spiked with sub-lethal concentrations of polychlorinated biphenyls (PCBs) (0, 0.5, 1, 5, 10, or 25 mg/kg Aroclor 1254). Univariate statistical analysis of the identified metabolites revealed a significant increase in ATP concentration in earthworms exposed to the highest soil PCB concentration, but detected no significant changes in other metabolites. However, a multivariate approach which considers alterations in multiple metabolites simultaneously, identified a significant linear relationship between earthworm metabolic profiles and PCB concentration (cross-validated PLS-regression with 7 components, R²X = 0.99, R²Y = 0.77, Q²Y = 0.45, P < 0.001). Significant changes in pair-wise metabolic correlations were also detected as PCB concentration increased. For example, lysine and ATP concentrations showed no apparent correlation in control earthworms (r = 0.22, P = 0.54), but were positively correlated in earthworms from the 25 mg/kg treatment (r = 0.87, P = 0.001). Overall, the observed metabolic responses suggest that PCBs disrupted both carbohydrate (energy) metabolism and membrane (osmolytic) function in E. fetida. The ability of ¹H NMR-based metabolomics to detect these responses suggests that this method offers significant potential for direct assessment of sub-lethal PCB toxicity in soil.     

Local Radiation Treatment of HER2-Positive Breast Cancer Using Trastuzumab-Modified Gold Nanoparticles Labeled with <Superscript>177</Superscript>Lu

Purpose

To compare the effectiveness of trastuzumab-modified gold nanoparticles (AuNP) labeled with ¹⁷⁷Lu (trastuzumab-AuNP-¹⁷⁷Lu) targeted to HER2 with non-targeted AuNP-¹⁷⁷Lu for killing HER2-overexpressing breast cancer (BC) cells in vitro and inhibiting tumor growth in vivo following intratumoral (i.t.) injection.

Methods

AuNP (30 nm) were modified with polyethylene glycol (PEG) polymers linked to trastuzumab or to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelators to complex ¹⁷⁷Lu. The binding and internalization of trastuzumab-AuNP-¹⁷⁷Lu in HER2-positive SK-BR-3, BT-474 and MDA-MB-361 human BC cells were studied. Clonogenic survival and DNA double-strand breaks (DSBs) were measured after exposure of SK-BR-3 or MDA-MB-361 cells to trastuzumab-AuNP-¹⁷⁷Lu or AuNP-¹⁷⁷Lu. NOD/SCID mice with s.c. MDA-MB-361 tumor xenografts were treated by i.t. injection of 3 MBq (0.15 mg) of trastuzumab-AuNP-¹⁷⁷Lu, AuNP-¹⁷⁷Lu or normal saline. Tumor growth was measured over 16 days and normal tissue toxicity evaluated.

Results

Trastuzumab-AuNP-¹⁷⁷Lu was bound and internalized by HER2 positive BC cells (K_D?=?7.6?±?2.0 nM). Trastuzumab-AuNP-¹⁷⁷Lu was 42.9 and 2.6-fold more effective than AuNP-¹⁷⁷Lu at decreasing the clonogenic survival of SK-BR-3 (1.3?×?10⁶ HER2/cell) and MDA-MB-361 (5.1?×?10⁵ HER2/cell) cells, respectively, exposed overnight to these agents (1.5 nM; 20 MBq/mg Au). Under the same treatment conditions, 10-fold and 2.8-fold more DNA DSBs were observed in SK-BR-3 and MDA-MB-361 cells, respectively, exposed to trastuzumab-AuNP-¹⁷⁷Lu than AuNP-¹⁷⁷Lu. Trastuzumab-AuNP-¹⁷⁷Lu was 1.8-fold more effective at inhibiting tumor growth than AuNP-¹⁷⁷Lu. No or minimal normal tissue toxicity was observed for trastuzumab-AuNP-¹⁷⁷Lu or AuNP-¹⁷⁷Lu treatments.

Conclusion

Trastuzumab-AuNP-¹⁷⁷Lu enables an efficient local radiation treatment of HER2-positive BC.

     

In vivo affinity of [<Superscript>18</Superscript>F]fallypride for striatal and extrastriatal dopamine D<Subscript>2</Subscript> receptors in nonhuman primates

Rationale [¹⁸F]Fallypride is a new and promising radiotracer, suitable for imaging D₂ receptors with Positron Emission Tomography (PET) in both striatal and extrastriatal regions. The high signal to noise ratio of [¹⁸F]fallypride has been attributed to its high affinity for D₂ receptors (K_D of 0.03 nM, measured in vitro at room temperature).Objectives We sought to further characterize this tracer in terms of its in vivo affinity, possible affinity differences between brain regions and dependence of in vitro affinity on temperature.Methods PET scans were performed in baboons over a wide range of concentrations to measure the in vivo K_D of [¹⁸F]fallypride in striatal and extrastriatal regions. Several analytical approaches were used, including nonlinear kinetic modeling and equilibrium methods. Also, in vitro assays were performed at 22 and 37°C.Results No significant differences in the in vivo K_D were detected between regions. In vivo K_D of [¹⁸F]fallypride was 0.22±0.05 nM in striatum, 0.17±0.05 nM in thalamus, and 0.21±0.07 nM in hippocampus. These values were intermediate between in vitro K_D measured at 22 (0.04±0.03 nM) and 37 degrees (2.03±1.07 nM).Conclusion The in vivo affinity of [¹⁸F]fallypride was not as high as previously estimated from in vitro values. This property might contribute to the favorable kinetic properties of the tracer. The in vivo affinity was similar between striatal and extrastriatal regions. This result indicates that the measured regional in vivo affinities of this tracer are not affected by putative regional differences in endogenous dopamine, and that [¹⁸F]fallypride is an appropriate tool to provide unbiased estimates of the occupancy of D₂ receptors by antipsychotic drugs in striatal and extrastriatal regions.     

Demonstration of Nucleoside Transporter Activity in the Nose-to-Brain Distribution of [<Superscript>18</Superscript>F]Fluorothymidine Using PET Imaging

To evaluate the role of nucleoside transporters in the nose-to-brain uptake of [¹⁸F]fluorothymidine (FLT), an equilibrative nucleoside transporter (ENT1,2) and concentrative nucleoside transporter (CNT1–3) substrate, using PET to measure local tissue concentrations. Anesthetized Sprague-Dawley rats were administered FLT by intranasal (IN) instillation or tail-vein injection (IV). NBMPR (nitrobenzylmercaptopurine riboside), an ENT1 inhibitor, was administered either IN or intraperitoneally (IP). Dynamic PET imaging was performed for up to 40 min. A CT was obtained for anatomical co-registration and attenuation correction. Time-activity curves (TACs) were generated for the olfactory bulb (OB) and remaining brain, and the area-under-the-curve (AUC) for each TAC was calculated to determine the total tissue exposure of FLT. FLT concentrations were higher in the OB than in the rest of the brain following IN administration. IP administration of NBMPR resulted in increased OB and brain FLT exposure following both IN and IV administration, suggesting that NBMPR decreases the clearance rate of FLT from the brain. When FLT and NBMPR were co-administered IN, there was a decrease in the OB AUC while an increase in the brain AUC was observed. The decrease in OB exposure was likely the result of inhibition of ENT1 uptake activity in the nose-to-brain transport pathway. FLT distribution patterns show that nucleoside transporters, including ENT1, play a key role in the distribution of transporter substrates between the nasal cavity and the brain via the OB.     

Effects of carbamazepine and amitriptyline on tetrodotoxin-resistant Na<Superscript>+</Superscript> channels in immature rat trigeminal ganglion neurons

Although anticonvulsant drugs that block voltage-dependent Na⁺ channels have been widely used for neuropathic pain, including peripheral nerve injury-induced pain, much less is known about the actions of these drugs on immature trigeminal ganglion (TG) neurons. Here we report the effects of carbamazepine (CBZ) and amitriptyline (ATL) on tetrodotoxin-resistant (TTX-R) Na⁺ channels expressed on immature rat TG neurons. TTX-R Na⁺ currents (I_Na) were recorded in the presence of 300 nM TTX by use of a conventional whole-cell patch clamp method. Both CBZ and ATL inhibited TTX-R I_Na in a concentration-dependent manner, but ATL was more potent. While CBZ and ATL did not affect the overall voltage-activation relationship of TTX-R Na⁺ channels, both drugs shifted the voltage-activation relationship to the left, indicating that they inhibited TTX-R Na⁺ channels more efficiently at depolarized membrane potentials. ATL showed a profound use-dependent blockade of TTX-R I_Na, but CBZ had little effect. The present results suggest that both CBZ and ATL, common drugs used for treating neuropathic pain, efficiently inhibit TTX-R Na⁺ channels expressed on immature TG neurons, and that these drugs might be useful for the treatment of trigeminal nerve injury-induced neuropathic pain, as well as the inhibition of ongoing central sensitization, even during immature periods.     

Roles of Na<Superscript>+</Superscript>/Ca<Superscript>2+</Superscript> exchanger isoforms NCX1 and NCX2 in motility in mouse ileum

The Na⁺/Ca²⁺ exchanger (NCX) is a plasma membrane transporter that is involved in regulating intracellular Ca²⁺ concentrations in various tissues. The physiological roles by which NCX influences gastrointestinal motility are incompletely understood, although its role in the heart, brain, and kidney has been widely investigated. In this study, we focused on the functions of the NCX isoforms, NCX1 and NCX2, in the motility of the ileum in the gastrointestinal tract. We investigated the response to electric field stimulation (EFS) in the longitudinal smooth muscle of the ileum obtained from wild-type mice (WT), NCX1-heterozygote knockout mice (NCX1 HET), NCX2 HET and smooth muscle-specific NCX1.3 transgenic mice (NCX1.3 Tg). EFS induced a phasic contraction that persisted during EFS and a tonic contraction that occurred after the end of EFS. We found that the amplitudes of the phasic and tonic contractions were significantly smaller in NCX2 HET, but not in NCX1 HET, compared to WT. Moreover, the magnitudes of acetylcholine (ACh)- and substance P (SP)-induced contractions of NCX2 HET, but not of NCX1 HET, were smaller compared to WT. In contrast, the amplitudes of the phasic and tonic contractions were greater in NCX1.3 Tg compared to WT. Similar to EFS, the magnitude of ACh-induced contraction was greater in NCX1.3 Tg than in WT. Taken together, our findings indicated that NCX1 and NCX2 play important roles in ileal motility and suggest that NCX1 and NCX2 regulate the motility in the ileum by controlling the sensitivity of smooth muscles to ACh and SP.     

Dopamine Increases CD14<Superscript>+</Superscript>CD16<Superscript>+</Superscript> Monocyte Transmigration across the Blood Brain Barrier: Implications for Substance Abuse and HIV Neuropathogenesis

In human immunodeficiency virus-1 (HIV) infected individuals, substance abuse may accelerate the development and/or increase the severity of HIV associated neurocognitive disorders (HAND). It is proposed that CD14⁺CD16⁺ monocytes mediate HIV entry into the central nervous system (CNS) and that uninfected and infected CD14⁺CD16⁺ monocyte transmigration across the blood brain barrier (BBB) contributes to the establishment and propagation of CNS HIV viral reservoirs and chronic neuroinflammation, important factors in the development of HAND. The effects of substance abuse on the frequency of CD14⁺CD16⁺ monocytes in the peripheral circulation and on the entry of these cells into the CNS during HIV neuropathogenesis are not known. PBMC from HIV infected individuals were analyzed by flow cytometry and we demonstrate that the frequency of peripheral blood CD14⁺CD16⁺ monocytes in HIV infected substance abusers is increased when compared to those without active substance use. Since drug use elevates extracellular dopamine concentrations in the CNS, we examined the effects of dopamine on CD14⁺CD16⁺ monocyte transmigration across our in vitro model of the human BBB. The transmigration of this monocyte subpopulation is increased by dopamine and the dopamine receptor agonist, SKF 38393, implicating D1-like dopamine receptors in the increase in transmigration elicited by this neurotransmitter. Thus, elevated extracellular CNS dopamine may be a novel common mechanism by which active substance use increases uninfected and HIV infected CD14⁺CD16⁺ monocyte transmigration across the BBB. The influx of these cells into the CNS may increase viral seeding and neuroinflammation, contributing to the development of HIV associated neurocognitive impairments.     

Extraction, radiolabeling, and biodistribution of thebaine in rats

The goal of this study was to determine the radiopharmaceutical potential of radioiodinated thebaine. Thebaine was extracted from dry capsules of opium poppy (Papaver somniferum L.), purified using high-performance liquid chromatography, and characterized with nuclear magnetic resonance and infrared spectroscopy. The purified thebaine was labeled with ¹³¹I using the iodogen method. Normal and receptor-blockage biodistribution studies were performed in male Albino Wistar rats. The results of the tissue distribution studies showed that the uptake of ¹³¹I-thebaine in the stomach, large intestine, spinal cord, and prostate was higher than in the other tissues. A greater uptake of radiolabeled thebaine in the rat brain was observed in the midbrain and hypothalamus. We concluded that (1) the labeling yield of ¹³¹I-thebaine was high, (2) a large amount of ¹³¹I-thebaine remained in the midbrain and hypothalamus, and (3) ¹³¹I-thebaine had enough stability for diagnostic scanning.     

Synthesis and biological characterization of <Superscript>99m</Superscript>Tc-labeled ciprofloxacin

Investigations aimed at the creation of a standard kit for the synthesis of ^99mTc-labeled ciprofloxacin (fluoroquinolone antibiotic) have been carried out. For isotope labeling, eluate from a technetium-99m generator was added to dry sterile mixtures of ciprofloxacin hydrochloride (CFH) with a reducing agent (tin chloride, SnCl₂) in various ratios. The mixtures were incubated for 20 min at room temperature. The influence of components of the reaction mixture on the amount of radiochemical impurity in the resulting radiopharmaceuticals was estimated using TLC. Three ^99mTc-containing complexes and a colloid related to the hydrolysis of tin compounds were formed. The tin content in each complex has been determined by introducing a ^117mSn isotope label. Ways to decrease colloid formation by changing the pH of the medium and by reducing the SnCl₂ concentration in the kit have been investigated. The kit composition has been optimized. It is established that radiopharmaceuticals containing less than 0.175 mg SnCl₂ per 5 mg CFH can be used without additional filtration. Tests on experimental animals (rabbits) with model inflammation in soft tissues showed the functional suitability of ^99mTc-labeled ciprofloxacin for diagnosis of infectious-inflammatory processes.     

Gastroprotective effect of anti-cancer compound rohitukine: possible role of gastrin antagonism and H<Superscript>+</Superscript> K<Superscript>+</Superscript>-ATPase inhibition

The present study was designed to evaluate the anti-ulcerogenic properties of an alkaloid chromane, rohitukine from Dysoxylum binectariferum. Anti-ulcer potential of rohitukine was assessed in cold restrained, pyloric ligated and ethanol induced ulcers in rats. In addition, rohitukine was tested in vitro for H⁺ K⁺-ATPase inhibitory activity in gastric microsomes. Moreover, we studied the role of rohitukine on the cytosolic concentration of Ca²⁺ in parietal cell-enriched cell suspension in order to ascertain its mechanism of action. Cytoprotective activity was evaluated through PGE₂ level. Rohitukine significantly attenuated the ulcers in cold restraint ulcer (CRU) model in a dose-related manner. Moreover, it significantly lowered the free acidity and pepsin activity in pyloric ligated rats while improved the depleted level of mucin. Furthermore, rohitukine significantly reversed the cold restrained-induced increase in gastrin level. Our in vitro study revealed that rohitukine moderately inhibited the microsomal H⁺ K⁺-ATPase activity with respect to positive control omeprazole. Furthermore, rohitukine potently antagonized the gastrin-elicited increase in cytosolic Ca²⁺ level in parietal cell-enriched suspension. In ethanol-induced gastric lesions in rats, rohitukine significantly inhibited the formation of erosions and increased PGE₂ content showing more potency than reference drug sucralfate. Our results thus suggest that rohitukine possess significant anti-ulcer and anti-gastrinic activity in rats. It is likely that gastro-protective influences of rohitukine are dependent partly on its acid-lowering potential and partly on cytoprotective property. The acid-reducing effect of rohitukine might be attributed to its lowering effect on gastrin production and/or antagonism of gastrin-evoked functional responses of parietal cells. Thus, rohitukine represent a useful agent in the treatment of peptic ulcer disease.