Sodium pertechnetate (Na99mTcO4) biodistribution in mice exposed to cigarette smoke

Background

The biological effects of cigarette smoke are not fully known. To improve our understanding of the action of various chemical agents, we investigated the biodistribution of sodium pertechnetate (Na^99mTcO₄) in mice exposed to cigarette smoke.

Methods

Fifteen BALB/c male mice were exposed to the smoke of nine whole commercial cigarettes per day, 3 times/day, for up to 10 days to whole body exposure in a chamber. A control group of 5 BALB/c male mice was sham-smoked. One day later, the exposed and control groups of mice received (7.4 MBq/0.3 ml) of Na^99mTcO₄ before being killed at 30 min. Bones, brain, heart, intestine, kidney, liver, lungs, muscle, pancreas, spleen, stomach, testis and thyroid were weighed and these organs and blood radioactivity recorded with a gamma counter. The percentage per gram of tissue of injected dose (%ID/g) was determined for each organ.

Results

Cigarette smoke significantly decreased (p < 0.05) the %ID/g in red blood cells, bone, kidney, lung, spleen, stomach, testis and thyroid of the exposed mice.

Conclusion

The toxic effects of cigarette smoke reduced the Na^99mTcO₄ biodistribution.     

SPECT/CT imaging of radiolabeled cubosomes and hexosomes for potential theranostic applications

We have developed a highly efficient method for the radiolabeling of phytantriol (PHYT)/oleic acid (OA)-based hexosomes based on the surface chelation of technetium-99m (^99mTc) to preformed hexosomes using the polyamine 1, 12-diamino-3, 6, 9-triazododecane (SpmTrien) as chelating agent. We also report on the unsuccessful labeling of cubosomes using the well-known chelating agent hexamethylpropyleneamine oxime (HMPAO). The ^99mTc-labeled SpmTrien-hexosomes (^99mTc-SpmTrien-hexosomes) were synthesized with good radiolabeling (84%) and high radiochemical purity (>90%). The effect of radiolabeling on the internal nanostructure and the overall size of these aqueous dispersions was investigated by using synchrotron small angle X-ray scattering (SAXS), dynamic light scattering (DLS), and transmission electron cryo microscopy (cryo-TEM). Further, we show the utility of ^99mTc-SpmTrien-hexosomes for the in vivo imaging of healthy mice using single photon emission computed tomography (SPECT) in combination with computed tomography (CT), i.e. SPECT/CT. SPECT/CT experiments of subcutaneously administered ^99mTc-SpmTrien-hexosomes to the flank of mice showed a high stability in vivo allowing imaging of the distribution of the radiolabeled hexosomes for up to 24 h. These injected ^99mTc-SpmTrien-hexosomes formed a deposit within the subcutaneous adipose tissue, displaying a high biodistribution of ∼343% injected dose/g tissue (%ID/g), with negligible uptake in other organs and tissues. The developed ^99mTc labeling method for PHYT/OA-based hexosomes could further serve as a useful tool for investigating and imaging the in vivo performance of cubosomal and hexosomal drug nanocarriers.     

Functional investigation of bone implant viability using radiotracers in a new model of osteonecrosis

OBJECTIVES:Conventional imaging methods are excellent for the morphological characterization of the consequences of osteonecrosis; however, only specialized techniques have been considered useful for obtaining functional information. To explore the affinity of radiotracers for severely devascularized bone, a new mouse model of isolated femur implanted in a subcutaneous abdominal pocket was devised. To maintain animal mobility and longevity, the femur was harvested from syngeneic donors. Two technetium-99m-labeled tracers targeting angiogenesis and bone matrix were selected.METHODS:Medronic acid and a homodimer peptide conjugated with RGDfK were radiolabeled with technetium-99m, and biodistribution was evaluated in Swiss mice. The grafted and control femurs were evaluated after 15, 30 and 60 days, including computed tomography (CT) and histological analysis.RESULTS:Radiolabeling achieved high (>95%) radiochemical purity. The biodistribution confirmed good blood clearance 1 hour after administration. For ^99mTc-hydrazinonicotinic acid (HYNIC)-E-[c(RGDfK)₂, remarkable renal excretion was observed compared to ^99mTc-methylene diphosphonate (MDP), but the latter, as expected, revealed higher bone uptake. The results obtained in the control femur were equal at all time points. In the implanted femur, ^99mTc-HYNIC-E-[c(RGDfK)₂ uptake was highest after 15 days, consistent with early angiogenesis. Regarding ^99mTc-MDP in the implant, similar uptake was documented at all time points, consistent with sustained bone viability; however, the uptake was lower than that detected in the control femur, as confirmed by histology.CONCLUSIONS:1) Graft viability was successfully diagnosed using radiotracers in severely ischemic bone at all time points. 2) Analogously, indirect information about angiogenesis could be gathered using ^999mTc-HYNIC-E-[c(RGDfK)₂. 3) These techniques appear promising and warrant further studies to determine their potential clinical applications.     

Alternative chromatographic system for the quality control of lipophilic technetium-99m radiopharmaceuticals such as [99mTc(MIBI)6]+

Knowledge of the radiochemical purity of radiopharmaceuticals is mandatory and can be evaluated by several methods and techniques. Planar chromatography is the technique normally employed in nuclear medicine since it is simple, rapid and usually of low cost. There is no standard system for the chromatographic technique, but price, separation efficiency and short time for execution must be considered. We have studied an alternative system using common chromatographic stationary phase and alcohol or alcohol:chloroform mixtures as the mobile phase, using the lipophilic radiopharmaceutical [^99mTc(MIBI)₆]⁺ as a model. Whatman 1 modified phase paper and absolute ethanol, Whatman 1 paper and methanol:chloroform (25:75), Whatman 3MM paper and ethanol:chloroform (25:75), and the more expensive ITLC-SG and 1-propanol:chloroform (10:90) were suitable systems for the direct determination of radiochemical purity of [^99mTc(MIBI)₆]⁺ since impurities such as^99mTc-reduced-hydrolyzed (RH),^99mTcO₄ ^- and [^99mTc(cysteine)₂]^-complex were completely separated from the radiopharmaceutical, which moved toward the front of chromatographic systems while impurities were retained at the origin. The time required for analysis was 4 to 15 min, which is appropriate for nuclear medicine routines.     

Nax-deficient mice show normal vasopressin response to dehydration

In dehydrated animals, the antidiuretic hormone vasopressin (VP) is released from the nerve terminals of magnocellular neurons of the supraoptic nucleus (SON) and paraventricular nucleus (PVN) into the systemic circulation at the posterior pituitary. Increases in sodium (Na⁺)-level and osmolality in body fluids upon dehydration are reportedly sensed by a Na⁺-sensor and/or an osmosensor, respectively. However, it is still unknown whether both are involved in the regulation of production and/or release of VP. Na_x is the cerebral Na⁺-level sensor and Na_x-knockout mice do not stop ingesting salt even when dehydrated. Here we examined VP production/release in Na_x-knockout mice, and found that they are normal in the VP response to dehydration or intraperitoneal-administration with hypertonic saline. In situ hybridization using an intron-specific probe showed that VP gene expression in the SON did not differ from wild-type mice when dehydrated. Also, there was no significant difference in the activity of subfornical organ neurons projecting to the SON between the two genotypes when stimulated by water deprivation. Furthermore, Na_x-knockout mice showed a normal response in urine excretion to dehydration. All these results indicate that the information of Na⁺-level increase detected by Na_x does not contribute to the control of VP production/release.     

Changes of the peripheral nerve excitability in vivo induced by the persistent Na current blocker ranolazine

Persistent Na⁺ current (Na_p) in the peripheral axons play an important functional role in controlling the axonal excitability. Abnormal Na_p is believed to contribute to neurodegeneration and neuropathic pain, and thus it is an attractive therapeutic target. To assess the behavior of selective Na_p blockade, axonal excitability testing was performed in vivo in 10 normal male mice exposed to ranolazine by recording the tail sensory nerve action potentials (SNAPs). Twenty minutes after administering ranolazine i.p. (50 mg/kg), the following changes were observed: lower SNAP amplitudes and the need for greater stimulus currents; greater threshold changes induced by long hyperpolarizing currents; reduced accommodation to long depolarizing current along with reduced late subexcitability; and reduced strength-duration time constant. These changes are explained by the suppression of Na_p leading to greater threshold currents, partial block of transient Na⁺ current, and suppression of slow K⁺ currents. The suppressed slow K⁺ currents appear to limit the modification of the membrane excitability by ranolazine. This study confirms the utility of axonal excitability testing as a useful treatment biomarker in neurological conditions in which Na_p function is being modified.     

Lactogenic Activity of Rats Stimulated by Gunnera Perpensa L. (Gunneraceae) from South Africa

Gunnera perpensa L. (Gunneraceae) is a medicinal plant used by Zulu traditional healers to stimulate milk production. The effect of an aqueous extract of the rhizome of the plant on milk production in rats was investigated. Female lactating rats that received oral doses of the extract of G.perpensa significantly (p<0.05) produced more milk than controls. The plant extract did not however, significantly influence the levels of prolactin, growth hormone, progesterone, cortisol, ALT, AST and albumin in the blood. The mammary glands of rats treated with the extract showed lobuloalveolar development. The extract (0.8 µg/ml) was also found to stimulate the contraction of the uterus and inhibit (23%) acetylcholinesterase activity. The cytotoxicity of the extract (LC₅₀) to two human cell lines (HEK293 and HepG2) was 279.43 µg/ml and 222.33µg/ml, respectively. It is inferred that the plant extract exerts its activity on milk production and secretion by stimulating lobuloalveolar cell development and the contraction of myoepithelial cells in the alveoli. It is concluded that Gunnera perpensa contains constituents with lactogenic activity that apparently contribute to its effectiveness in folk medicine.     

Antidiabetic and haematinic effects of Parquetina nigrescens on alloxan induced type-1 diabetes and normocytic normochromic anaemia in Wistar rats

Background

The plant, Parquetina nigrescens is used in folklore medicine to treat diabetes mellitus and its complications in several parts of West Africa.

Objective

To determine the effect of Parquetina nigrescens extract on fasting blood glucose in alloxan-induced diabetic rats.

Methods

The blood glucose levels, complete blood count, erythrocyte indices and osmotic fragility, body and organ weights were evaluated.

Results

Diabetic rats treated with the extract showed significant (P<0.01) reduction of the blood glucose to levels comparable to that of the non-diabetic control and those treated with chlorpropamide (standard drug). Similarly, there was significant (P<0.01) reduction in the complete blood count in the diabetic rats.

Discussion

The anaemia, leucopenia and thrombocytopenia associated with the diabetes were corrected in the animals treated with the extract and chlorpropamide. The extract also reduced the erythrocyte osmotic fragility, body and organ weights. Parquetina nigrescens demonstrated antidiabetic property by reducing the elevated blood glucose in alloxan treated rats which is comparable to animals that received the standard drug.

Conclusion

Paraquetina nigrescens stabilized the erythrocyte membrane, decreased the body weight probably by lowering lipogenesis. However, the mechanism underlying the antidiabetic and haematinic properties of Parquetina nigrescens remains to be elucidated.     

Lipid Fraction Constituents and Evaluation of Anti-Anaphylactic Activity of Prunus Mahaleb L. Kernels

The lipid fraction constituents as well as evaluation of anti-anaphylactic activity of Prunus mahaleb L. Kernels were studied. Prunus mahaleb L. kernels were obtained from the local market in Cairo, Egypt. Investigation of the fatty acids revealed that oleic and linoleic acids are the major constituents. 12 compounds were identified from the hydrocarbon fraction. The sterol fraction comprises of cholesterol, stigmasterol, β-sitosterol and campesterol. The pharmacotoxicity studies were carried out on total and defatted ethanolic extracts as well as the oil fraction. The oil fraction proved to be extremely safe and free from any acute lethal toxicity in intraperitoneal (i.p.) and oral doses up to 100 ml/kg. Invivo assessment of prophylactic efficacy was afforded by 7 days course of daily medication schedule of sensitized adult male guinea pigs against ovalbumin bronchospasm. The prophylactic anti-inflammatory activity of the total ethanolic extract was higher than that of the defatted ethanolic extract. In addition, the lipid fraction of Prunus mahaleb L. kernels evoked complete anti-inflammatory efficacy among the survival animals receiving low and medium doses.     

B lymphocytes regulate airway granulocytic inflammation and cytokine production in a murine model of fungal allergic asthma

Sensitization to fungi often leads to a severe form of asthma that is particularly difficult to manage clinically, resulting in increased morbidity and hospitalizations in these patients. Although B lymphocytes might exacerbate asthma symptoms through the production of IgE, these cells might also be important in the protective response against inhaled fungi. Through cytokine release and T-cell interactions, these lymphocytes might also influence the development and maintenance of airway wall fibrosis. J_H^−/− mice lack the JH gene for the heavy chain component of antibodies, which is critical for B-cell function and survival. These animals have facilitated the elucidation of the role of B lymphocytes in a number of immune responses; however, J_H^−/− mice have not been used to study fungal allergy. In this study, we examined the role of B lymphocytes using an Aspergillus fumigatus murine fungal aeroallergen model that mimics human airway disease that is triggered by environmental fungal exposure. We compared disease progression in sensitized wild-type BALB/c and J_H^−/− mice that were exposed to repeated fungal exposure and found no differences in airway hyperresponsiveness, overall pulmonary inflammation or collagen deposition around the large airways. However, the levels of the Th2-type cytokines IL-4 and IL-13 were significantly attenuated in the airways of J_H^−/− mice relative to the BALB/c controls. By contrast, levels of the inflammatory cytokines IL-17A and IL-6 were significantly elevated in the J_H^−/− animals, and there was significantly more robust airway eosinophilia and neutrophilia than in control animals. Taken together, these findings demonstrate that B lymphocytes help to regulate granulocytic responses to fungal exposure in the pulmonary compartment.     

The effect of Nigella sativa extract on tracheal responsiveness and lung inflammation in ovalbumin-sensitized guinea pigs

OBJECTIVE:

To examine the preventive effect of a hydro-ethanolic extract of Nigella sativa on the tracheal responsiveness and white blood cell count in the lung lavage fluid of sensitized guinea pigs.

METHODS:

Three groups of guinea pigs sensitized to intraperitoneally injected and inhaled ovalbumin were given drinking water alone (group S), drinking water containing a low concentration of N. sativa extract (group S+LNS) or drinking water containing a high concentration of N. sativa extract (group S+HNS). The tracheal responses of control animals (group C) and the three groups of sensitized guinea pigs (n = 7 for all groups) to methacholine were measured by the assessment of the tracheal smooth muscle response to increasing concentrations of methacholine, and the effective concentration causing 50% of the maximum response (EC₅₀) was determined. Tracheal responses to 0.1% ovalbumin and white blood cell counts in the lung lavage fluid were also examined.

RESULTS:

The tracheal response of the group S guinea pigs to both methacholine and ovalbumin was significantly higher than the response of the controls (p<0.01 for both cases). The tracheal responses of the S+LNS and S+HNS groups to both methacholine and ovalbumin were significantly decreased compared to those of the S group (p<0.05 to p<0.01). The total white blood cell and eosinophil counts in the lung lavage fluid of group S were significantly higher than those of group C (p<0.01). The white blood cell counts in both treated groups showed significant improvements (p<0.01 for both cases).

CONCLUSIONS:

These results demonstrate the preventive effect of the N. sativa extract on the tracheal response and lung inflammation in sensitized guinea pigs.     

Hepatoprotective Effect of Cymbopogon Citratus Aqueous Extract Against Hydrogen Peroxide-Induced Liver Injury in Male Rats

Background

Cymbopogon citratus (Poaceae) a tropical perennial herb plant that is widely cultivated to be eaten either fresh with food or dried in tea or soft drink has been reported to possess a number of medicinal and aromatic properties. This study aimed at evaluating the protective effects of C. citratus aqueous extract against liver injury induced by hydrogen peroxide (H₂O₂), in male rats.

Materials and Methods

Twenty-five rats were randomly divided into five different groups of five animals in each group; (1) Control. (2) Received H₂O₂ (0.5%) with drinking water. (3), and (4) received H₂O₂ and C. citratus (100 mg·kg⁻¹ b wt), vitamin C (250 mg·kg⁻¹ b wt) respectively. (5), was given C. citratus alone. The treatments were administered for 30 days. Blood samples were collected and serum was used for biochemical assay including liver enzymes activities, total protein, total bilirubin and malonaldehyde, glutathione in serum and liver homogenates. Liver was excised and routinely processed for histological examinations.

Results

C. citratus attenuated liver damage due to H₂O₂ administration as indicated by the significant reduction (p<0.05), in the elevated levels of ALT, AST, ALP, LDH, TB, and MDA in serum and liver homogenates; increase in TP and GSH levels in serum and liver homogenates; and improvement of liver histo-pathological changes. These effects of the extract were similar to that of vitamin C which used as antioxidant reference.

Conclusion

C. citratus could effectively ameliorate H₂O₂-induced oxidative stress and prevent liver injury in male rats.     

In vitro effects of mercuric chloride (HgCl2) on human mononuclear cells

Due to the release of the toxic compounds of mercury from amalgam fillings, dental amalgam has been questioned as an adequate restoration material for tooth fillings. HgCl₂ has been found to be mitogenic for human blood lymphocytes in vitro. However, activation required much higher concentrations than are ever found in vivo. This study has been initiated to evaluate further the influence of HgCl₂ on human immunocompetent cells in vitro. It is found that HgCl₂ in a narrow concentration range has the ability to preferentially stimulate the CD4⁺ T cell subset to blast transformation and DNA synthesis. The reaction, when monitored during days 2–6, is maximal at day 6, and most blasts express the IL-2 receptor (IL-2R), indicating in vitro activation. The CD8⁺ T cell subset is not affected to the same extent. In addition, HgCl₂-induced lymphocyte reactivity is dependent on accessory cells, i.e. CD14⁺ cells.     

Endothelium-Independent and Endothelium-Dependent Vasorelaxation by a Dichloromethane Fraction from Anogeissus Leiocarpus (DC) Guill. Et Perr. (Combretaceae): Possible Involvement of Cyclic Nucleotide Phosphodiesterase Inhibition

Many traditional medicinal herbs from Burkina Faso are used to treat arterial hypertension (HTA). Among them, Anogeissus leiocarpus (A. Leiocarpus) which is well known and widely used in Burkina traditional medicine. Herein we assess the effects of dichloromethane fraction from A. leiocarpus stem bark (ALF), selected as the most active on cyclic nucleotide phosphodiesterases (PDEs) and characterized its specificity towards purified vascular PDE1 to PDE5 isoenzymes and study its effects on a vascular model. ALF potently and preferentially inhibits (IC₅₀=1.6 ± 0.6 µg/mL) the calmodulin-dependent phosphodiesterase PDE1, being mainly present in vascular smooth muscle and preferentially hydrolyses cGMP. In the same range (IC₅₀ =2.8 ±0.2 µg/ml) ALF inhibits PDE2, a cGMP-activated enzyme that is only present in endothelial cells and hydrolyses both cAMP and cGMP. PDE5, which specifically hydrolyses cGMP and which mainly contributes to cGMP hydrolysis is also potently inhibited by ALF (IC₅₀=7.6±3.5 µg/ml). The potencies of ALF on cAMP hydrolyzing isoenzymes was lesser, being more effective on PDE4 (IC₅₀= 17.6±3.5 µg/ml) than on PDE3 (60.9 ± 1.8 µg/ml). Since the major effect of ALF were against cGMP hydrolysis and since cGMP is implicated in endothelium-dependent relaxation, the endothelium-dependent vasorelaxation was studied on isolated porcine coronary arteries rings pre-contracted with U46619. The endothelium-dependent vasorelaxation is significantly inhibited by N^ω-nitro-L-arginine (LNA 300 µmol/L, an inhibitor of endothelial NO synthase), but not affected by charybdotoxin (CTX, 100nM) plus apamin (APA, 100nM) (two inhibitors of EDHF-mediated responses). The combination of 4-aminopyridine (4-AP, 1 mmol/L, inhibitor of voltage-dependent potassium channels, K_v) plus baryum (Ba²⁺, 30 µmol/L, inhibitor of the potassium channels with entering correction, K_ir) plus ouabain (3 µmol/L, inhibitor of ATPase Na⁺/K⁺ channels) partially inhibits endothelium-independent vasorelaxant effect. This endothelium-independent relaxant effect was also sensitive to combination of 1H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin1-one (ODQ, 10 µM, soluble guanylyl cyclase inhibitor) and N-[2-(p-Bromocinnamylamino)ethyl]-5-isoquinoline sulfonamide dihydrochloride (H89, 100 nM, Protein Kinase A inhibitor). Taken together, these results indicate that ALF is a powerful vasodilator modulated by the formation of NO from endothelium, but also act by directly relaxing the vascular smooth muscle cells, by inhibiting cGMP hydrolyzing PDEs (PDE1, PDE2 and PDE5) and to a lesser extend on cAMP degradation (PDE3 and PDE4), cAMP and cGMP being second messengers involved in vascular relaxation.     

Biochemical and Toxicological Studies of Aqueous Extract of Syzigium Aromaticum (L.) Merr. & Perry (Myrtaceae) in Rodents

The effects of long-term administration of boiled aqueous extract of Syzigium aromaticum (SYZ), commonly known as clove (which has been locally employed for treating gastrointestinal tract diseases and also used as food spices), on some biochemical indices, such as body weight, liver functions and blood parameters were studied in adult albino rats of both sexes. Selected doses of 300 and 700 mg kg⁻¹ were given orally through cannular to groups of animals for a period of 90 days, while the control group received distilled water throughout the duration of study via the same route. Blood samples collected after therapy and assayed for activities of some liver enzymes recorded a significant (p<0.05) and prominent effect on ALP and AST. Measurement of haematological parameters also revealed significant effects (p<0.05; p<0.001) on Hb, RBC (p<0.05), PCV (p<0.001), platelets (p<0.001) and granulocytes (p<0.001). An insignificant reduction was recorded for total WBC. The histopathological study conducted was in consonance with the results of the biochemical investigations that the aqueous extract of SYZ even at moderate doses, significantly affects body organs, their enzymes as well as the various functions. LD₅₀ for both intraperitoneal and oral routes of SYZ were 263 and 2500 mg kg⁻¹ respectively. The present work has revealed the toxicity of sub chronic administration of SYZ, which suggests that its prolonged usage must be avoided.     

A quantitative analysis of the Na+-dependence of\dot V_{max} of the fast action potential in mammalian ventricular myocardium

In microelectrode experiments on papillary muscles of guinea pigs, the quantitative dependence of \(\dot V_{{\text{max}}} \) of the fast action potential, taken as a measure of I_Na, on external Na⁺ concentration has been analyzed under different experimental conditions including the presence of antiarrhythmic drugs such as lidocaine, procaine and propafenone.

1. External Na⁺ concentration changes between 225 mmol/l and 45 mmol/l led to a non-linear response of \(\dot V_{{\text{max}}} \) in that the \(\dot V_{{\text{max}}} \) changes obtained experimentally were significantly smaller than predicted theoretically from a linear dependence of \(\dot V_{{\text{max}}} \) on [Na⁺] _o .
2. Each individual \(\dot V_{{\text{max}}} \) relationship exhibited saturation characteristics. In Lineweaver-Burk plots, \(\dot V_{{\text{max}}} \) correlated extremely well to 1/[Na⁺] _o with correlation coefficients between 0.995 and 0.999. In 16 experiments, the apparentK _m for Na⁺ varied within a range from 170 to 455 mmol/l. Values of 450 V/s–900 V/s were calculated for the saturated \(\dot V_{{\text{max}}} \) (at an infinitely large [Na⁺] _o ).
3. The apparentK _m for Na⁺ rose from 232.0±24.7 mmol/l to 544.0±50.2 mmol/l when the K⁺ concentration of the medium was increased from 5.4 to 10 mmol/l and, thus, resting potential declined from ?90.5±2.5 mV to ?76.1±1.8 mV.
4. Alkalization (pH 9.0) of the medium lowered the apparentK _m for Na⁺ and, simultaneously, reduced the saturated \(\dot V_{{\text{max}}} \) . This typical shift of the straight relating \(\dot V_{{\text{max}}} \) to 1/[Na⁺] _o in the Lineweaver-Burk plot excludes a competitive interaction between Na⁺ and H⁺ ions.
5. Lidocaine (5×10^?5–2×10^?4 mol/l), procaine (2×10^?4 mol/l) and propafenone (0.5–3×10^?5 mol/l) depressed \(\dot V_{{\text{max}}} \) the stronger the lower [Na⁺] _o was. The changes of the \(\dot V_{{\text{max}}} \) relationship induced by these drugs indicated neither a competitive nor a non-competitive interaction of these compounds with Na⁺.
6. As tested with propafenone, external Na⁺ changes modulated the tonic and the phasic block of \(\dot V_{{\text{max}}} \) . The Na⁺ sensitivity of both types of block differed considerably. In a Na⁺-poor (50 mmol/l) medium, the apparentK _m for the tonic block declined from 5×10^?5 to 1.4×10^?5 mol/l and the apparentK _m for the phasic block from 3.8×10^?5 to 2.3×10^?5 mol/l.
7. Na⁺ is not the sole cation that determines the strength of a drug-induced blockade of \(\dot V_{{\text{max}}} \) as it can be substituted by the permeant Li⁺.
8. In the presence of drugs like propafenone which are capable of shifting the steady state inactivation (h _∞) of I_Na to more negative potentials, the voltage-dependence ofh _∞ can be modified by external Na⁺ variations. Na⁺ withdrawal led to a considerable shift in the hyperpolarizing direction.

     

Hypoglycemic Effect of Treculia Africana Decne Root Bark in Normal and Alloxan-Induced Diabetic Rats

The solvent partitioned purified fractions of the hydro-acetone root bark extract of the African breadfruit (Treculia africana Decne) were evaluated for hypoglycemic activities in normal and diabetic albino rats. Fasting blood glucose levels were estimated by the use of a glucometer at pre-determined intervals after oral administration of the test extracts/fractions. Results revealed that the test fractions have only a slight effect on blood sugar level of normal rats. On short term and chronic administration in diabetic rats however, diethyl ether-soluble (DEF) and the water-soluble (WSF) fractions significantly reduced the fasting blood sugar levels (p<0.05) at differing rates when compared with the control group of animals. The diethyl ether soluble fraction (10 mg kg⁻¹ dose level) was found to exhibit the highest activity giving 69.4% reduction in blood sugar level (at 240 hours) which was in comparable range with the reference standard glibenclamide (0.5 mg kg⁻¹) which reduced blood sugar levels by 65.8% below the initial baseline values.     

Effects of Vietnamese Sophora Root on Growth,Adhesion, Invasion and Motility of Melanoma Cells

Background

Vietnamese Sophora Root mainly contains active constituents such as alkaloids, and it has anti-tumour, antibacterial, and anti-inflammatory effects. The objective of the paper was to study the effects of Vietnamese Sophora Root on growth, adhesion, invasion and motility of mouse melanoma B₁₆BL₆ cells, and to preliminarily explore its mechanism of action.

Materials and Methods

MTT assay was used to detect the effect of Vietnamese Sophora Root aqueous extract on B₁₆BL₆ cell proliferation. Cell adhesion assay, reconstituted basement membrane invasion assay and chemotactic motility assay were used to observe the effects of Vietnamese Sophora Root aqueous extract on adhesion, invasion and motility of B₁₆BL₆ cells.

Results

Different concentrations of Vietnamese Sophora Root aqueous extracts had different degrees of inhibitory effects on B₁₆BL₆ proliferation. With the decrease of concentration, the proliferation inhibitory effect decreased and even turned to promoting effect. The extract significantly inhibited the adhesion of B₁₆BL₆ cells to the basement membrane component LN, and had a significant effect on both the invasive and migratory capacities of B₁₆BL₆ cells through the basement membrane.

Conclusion

We concluded that the aqueous extract of Vietnamese Sophora Root can inhibit the proliferation of melanoma cells, as well as their adhesion and movement.     

The Novel Antihyperglycaemic Action of Hunteria Umbellata Seed Fractions Mediated Via Intestinal Glucose Uptake Inhibition

The present study evaluated the antihyperglycaemic effect and mechanism of action of fractions of the aqueous seed extract of Hunteria umbellata (K. Schum.) Hallier f. (HU) in normal and alloxan-induced hyperglycaemic rats. HU was partitioned in chloroform, acetyl acetate and butan-1-ol to give chloroform fraction (HU_c), ethyl acetate fraction (HU_e), butanol fraction (HU_b) and the “residue” (HU_m), respectively. 200 mg/kg of each of these fraction dissolved in 5% Tween 20 in distilled water was investigated for its acute oral hypoglycaemic effects in normal rats over 6 hours while its repeated dose antihyperglycaemic effect was evaluated in alloxan-induced hyperglycaemic rats over 5 days. In addition, 50 mg/kg of the crude alkaloid fraction (HU_Af) extracted from HU was evaluated for its possible antihyperglycaemic activity in alloxaninduced hyperglycaemic rats using oral glucose tolerance test (OGTT) over 6 hours. Using the solvent system, distilled water-butanol-ammonium hydroxide (2:15:1, v/v/v), HU_b was chromatographed and stained with Dragendorff''s reagent for confirmatory qualitative analysis for alkaloids. Results showed that oral pre-treatment with 200 mg/kg of HU_e, HU_b and HU_m resulted in a significant (p<0.05, p<0.001) time dependent hypoglycaemic effect, with the butan-1-ol fraction HU causing the most significant (p<0.001) hypoglycaemic effect. In the alloxan-induced hyperglycaemic rats, repeated oral treatment with 200 mg/kg of same HU fractions for 5 days resulted in significant (p<0.05) decreases in the fasting blood glucose concentrations with the most significant (p<0.01) antihyperglycaemic effect also recorded for HU_b. Similarly, oral pretreatment with 50 mg/kg of HU_Af significantly (p<0.05, p<0.01 and p<0.001) attenuated an increase in the post-absorptive glucose concentration at 1^st – 6^th h in the alloxan-induced hyperglycaemic OGTT model. In addition, alkaloid was present in most of the separated spots on the TLC plate. In conclusion, results of this study showed that HU contains a relative high amount of alkaloids which could have accounted for the antihyperglycaemic action of HU that was mediated via intestinal glucose uptake inhibition.     

Antioxidative Potential of Duranta Repens (Linn.) Fruits Against H2O2 Induced Cell Death In Vitro

The effects of Duranta repens fruits were investigated on H₂O₂ induced oxidative cell death to evaluate its antioxidative potential in vitro. HEK293T cells were treated with different concentrations [0–1000 µg/ ml] of ethanol extract (E-Ex) and methanol extract (M-Ex) of D. repens for 24h, and then treated with 100 µM H₂O₂ for 24h. Cell viability, antioxidant parameters of cells, and antioxidant constituents of the extracts were determined. Treatment with limited dose of E-Ex or M-Ex increased the survival rate of H₂O₂-treated HEK293T cells, however the extra-high dose showed growth inhibitory effect. Treatment with E-Ex or M-Ex protected cellular lipid per-oxidation. In vitro analyses showed the 2,2-diphenyl-1-picrylhydrazyl and H₂O₂ scavenging activities as well as reducing potential of the extracts. We report here that the limited dose of E-Ex and M-Ex possess antioxidative potential, which can protect H₂O₂-induced oxidative cell damage.