Standardized experimental model for cement dust exposure; tissue heavy metal bioaccumulation and pulmonary pathological changes in rats.

A controlled experimental model of exposure to aerosols particularly for cement dust was recently invented in a study from the laboratory that found high serum levels of heavy metals, decrease gastrointestinal motility, and altered hematological variables in cement dust exposed rats. However, reproducibility was not considered. This work aims at standardizing the model and investigating preliminary toxicological indicators. Thirty male rats used in this study were divided into 3 groups (n = 10). Group 1; control, while groups 2 and 3 were exposed to cement dust for 14 days and 28 days respectively. We assessed clinical signs of toxicity, tissue heavy metal concentration, histopathological, and body weight (BW) changes. We observed poor movement coordination, abnormal posture, cephalic fur loss. Evidence of ischemia and fibrotic pneumoconiosis were grossly observed in the lungs of the exposed groups. There was a significant increase in tissue level of heavy metals with pulmonary and gastric heavy metal content showing a trendy relationship during the period of the exposure as the value of Lead, Chromium, Cadmium, Iron, Calcium, and Nickel increased by nearly similar percentages in both tissues. Organs weights increased; the 14-day exposed (198 ±â€¯31; 168 ±â€¯22) and 28-day exposed (198 ±â€¯22; 187 ±â€¯26) groups had significantly reduced body weight at the first and second weeks of exposure compared to the control group (265 ±â€¯26; 357 ±â€¯40) respectively. Exposure to cement dust induced low bone density in the exposed rats (p < 0.05). Histopathological alterations include necrosis, inflammatory cellular infiltration, and alveolar hyperplasia suggestive of the proliferative response of pulmonary tissue to the dust. The operation of the standardized apparatus mimics a typical occupational exposure and the findings show that cement dust induces systemic toxicity via respiratory perturbation and body/organ weight discordance mediated by heavy metal bioaccumulation.

Role of Nitric Oxide and Endogenous Antioxidants in Thyroxine Facilitated Healing of Ischemia-Reperfusion Induced Gastric Ulcers

Background: Studies have revealed the role of thyroxine during healing of gastric ulcers with information lacking on the mechanism involved hence the focus of this study.Materials and Methods: Adult male Wistar rats (150 ­ 200g) were randomly divided into 4 groups (n=5 per group): Normal control (NC), Sham ulcerated (SU), Thyroidectomised ulcerated untreated (ThU) and Thyroidectomised ulcerated + Levo-thyroxine (100µg/kg/day) (ThU + T4). Animals were stabilised for 35 days following thyroidectomy and treated accordingly to experimental groupings. Weekly body weight changes were recorded, gastric ulcer was induced by ischemia-reperfusion and gastric acid secretion evaluated. They were sacrificed 1 hour, 3 and 7 days post ulcer induction, blood samples collected for haematological indices through cardiac puncture and their stomachs prepared for gross and microscopic examinations to assess gastric healing. Gastric tissue protein, malondialdehyde (MDA), Superoxide Dismutase (SOD), Catalase (CAT), and Nitric oxide (NO) were assessed as biomarkers of healing. Data were analysed using one way ANOVA and Student's t test with p< 0.05 considered statistically significant.Results: Thyroxine treated rats showed significant weight loss compared with NC and ThU groups. Percentage healing rate was significantly increased in thyroxine treated group compared with ThU animals by 1 hour (42.45% and -42.81%), days 3 (35.14% and -59.36%), and 7 (64.29% and -115.7%).Hematological indices significantly increased in thyroxine treated group compared with other groups. Thyroxine treatment significantly reduced Neutrophil/Lymphocyte; Platelet/NO as well as lipid peroxidation index in this study.Superoxide dismutase, CAT and NO increased significantly in thyroxine treated rats compared with other groups.Conclusion: Thyroxine treatment facilitates the healing of ischeamic-reperfused gastric ulcers possibly by increasing NO activity which in turn causes increased vasodilatation and enhanced endogenous antioxidants at the ulcer sites

Effect of zinc treatment on intestinal motility in experimentally induced diarrhea in rats.

Zinc supplementation is a critical new intervention for treating diarrheal episodes in children. Recent studies suggest that administration of zinc along with new low osmolarity oral rehydration solutions / salts (ORS) can reduce the duration and severity of diarrheal episodes for up to three months. Several mechanisms of action of zinc has been proposed, however there is dearth of information about the effect of zinc on intestinal motility during diarrhea. Male albino Wistar rats (80-100g) were used. The effect of different doses of zinc sulphate (25, 50, 100, 150 mg/Kg) on the number of wet faeces was investigated. Intestinal motility during castor oil induced diarrhea was assessed using activated charcoal meal and the mechanisms of action of zinc sulphate on motility were investigated. The effective dose of zinc sulphate (100mg/Kg) significantly reduced (p< 0.001) the number of wet faeces (3.0 ± 0.00) compared with control (6.8 ± 0.25) during diarrhea. This antidiarrheal effect of zinc was abolished by propranolol and nifedipine. Zinc sulphate significantly reduced (p< 0.05) intestinal transit time (60.7 ± 7.13%) compared with control (85.7 ± 2.35%). It is concluded that zinc sulphate reduces the frequency of wet faeces output and intestinal motility during diarrhea via activation of ß adrenergic receptor and L-type Ca2+ channel.

Analgesic and anti-inflammatory properties of the leaf extracts of Anacardium occidentalis in the laboratory rodents.

Anacardium occidentalis (family: Anacardiaceae) is a plant of the tropical climate widely used by folklore to treat pain and inflammation. This study was conducted to evaluate the analgesic and anti-inflammatory effects of the leaf extracts in rat and mice using different models in other to confirm folkloric claims. The aqueous, hexane, dichloromethane and methanol extracts (AEAO, HEAO, DEAO and MEAO respectively) were investigated for analgesic effects in acetic acid induced pain in mice. They significantly reduced the number of writhing (p<0.001) and the highest analgesic effect was seen in DEAO extract. DEAO was further studied on various analgesic and anti-inflammatory models in graded doses. The extract significantly reduced writhing induced by acetic acid and the number and time of paw licking induced by formalin in a dose related manner. It inhibited the neurogenic and inflammatory phases of formalin. Analgesia was shown in the inhibition of nociception induced by tail immersion in 55oC hot water. The extract prolonged the latencies of tail withdrawal to a similar degree as pentazocine. The extract caused significant inhibition of carrageenan induced paw oedema in rats in a dose dependent manner. These findings suggest that the leaf extracts of Anacardium occidentalis are highly potent analgesic and anti-inflammatory agents. Phytochemical analysis showed that the leaf extracts contain alkaloids, tannins, saponins and cardenolides.

Augmentation of gastric acid secretion by chloroquine and amodiaquine in the rat stomach.

Gastrointestinal mucosal integrity has been shown to be altered by chloroquine and amodiaquine, although the exact mechanism is not clear. Since Gastric Acid Secretion (GAS) plays significant role in the etiology of ulcer, the present study was aimed at investigating the effect of chloroquine and amodiaquine on GAS, Parietal Cell Mass (PCM) and Gastric Mucous Cell Population (GMP) in rats. Male albino wistar rats were randomly assigned into three groups viz: control, chloroquine (CQ, 3 mg/kg), amodiaquine (AQ, 10 mg/kg). Basal GAS as well as secretion in response to histamine and carbachol was measured by continuous perfusion of the stomach with normal saline (1ml/minute) under urethane anaesthesia (0.6 mg/100 g). After obtaining a steady basal output response to normal saline in all animals, the antimalaria drugs were administered intramuscularly and the peak responses to each drug obtained. Further assessment of the roles of histaminergic and muscarinic receptors were done using ranitidine (H2 antagonist) and atropine (M antagonist) in the treated animals. PCM and GMP were determined in the stomach samples by histometry. The basal acid output was 0.70 ± 0.01 mmol/10 mins. Chloroquine and amodiaquine produced increase in acid output to a peak of 1.35 ±0.03 mmol/10 mins (92.9%) and 1.40 ± 0.03 mmol/10 mins (100%) respectively. Histamine and carbachol elicited 107% and 100% increase acid secretion when compared with the basal output respectively. CQ and AQ potentiated histamine-induced secretory rate which peaked at 1.60 ± 0.02 mmol/10 mins and 1.70 ± 0.03 mmol/10 mins respectively. Similarly, the carbachol-induced acid secretory response was potentiated by CQ and AQ to a peak of 1.45 ± 0.02 mmol/10 mins and 1.50 ± 0.03 mmol/10 mins. Ranitidine and atropine attenuated histamine and carbachol induced acid secretion, but did not abolish it. CQ and AQ increased significantly the parietal cell numbers in the gastric mucosa (21±0.7 and 24±0.7 versus 15.2±0.8 control). On the other hand, mucus cell population was significant decreased by CQ and AQ (15±0.3 and 13±0.85 versus 17.4±0.5 control) respectively. Chloroquine and amodiaquine increased gastric acid secretion in rats. They stimulated histamine (H2) and muscarinic (M3) receptors, and enhanced parietal cell mass.

Effect of ethanolic extract of Cryptolepis sanguinolenta stem on in vivo and in vitro glucose absorption and transport: Mechanism of its antidiabetic activity.

OBJECTIVE: Extracts from various morphological parts of Cryptolepis sanguinolenta are widely used traditionally in folklore medicine in many parts of the world for the management, control, and/or treatment of a plethora of human ailments, including diabetes mellitus. In order to scientifically appraise some of the ethnomedical uses of Cryptolepis sanguinolenta, the present study was undertaken to investigate its influence at varying doses on intestinal glucose absorption and transport in relation to its hypoglycemic and hypolipidemic effects in rat experimental paradigms. MATERIALS AND METHODS: The animals used were divided into four groups. Control animals received 2 ml of distilled water, while treated groups received 50, 150, and 250 mg/kg bw of Cryptolepis sanguinolenta extract per oral respectively daily for 21 days. RESULTS: Cryptolepis sanguinolenta led to a significant decrease in glucose transport and absorption. It also caused significant reductions in plasma glucose, total cholesterol, triglyceride, and LDL cholesterol. Biochemical changes observed were suggestive of dose dependence. Histopathological studies also showed increased sizes of ß cells of the pancreas. CONCLUSION: The findings in these normoglycemic laboratory animals suggest that Cryptolepis sanguinolenta has hypoglycemic and hypolipidemic activities, possibly by reducing glucose absorption and transport, and enhancing the structural and functional abilities of the ß cells. This is the first study to report the effect of Cryptolepis sanguinolenta on intestinal glucose absorption. This effect could be attributed to its major bioactive principle, cryptolepine, an indoloquinoline alkaloid. This study thus lends credence to the use of Cryptolepis sanguinolenta in the management of diabetes mellitus.

Effect of folic acid supplementation on oxidative gastric mucosa damage and acid secretory response in the rat.

OBJECTIVE: This study investigated the antioxidative and antisecretory properties of folic acid in the rats' stomach. MATERIALS AND METHODS: Male Wistar rats were treated with 2 mg/kg diet of folic acid for 21 days. Gastric ulceration was induced by indomethacin, scored, and assayed to determine the concentration of total protein, mucus, malondialdehyde (MDA), catalase (CAT) and superoxide dismutase (SOD) in homogenized samples. Normal saline and Ranitidine treated group served as negative and positive control, respectively. Basal and stimulated acid secretion was measured by continuous perfusion method. RESULT: Indomethacin caused severe damage to the rats' stomach with an ulcer index of 4.32 ± 0.13, increase in MDA concentration and reduction in the concentration of protein, mucus, catalase and superoxide dismutase (P < 0.001). Pre-treatment with folic acid prevented the formation of ulcers by 32%, and attenuated the inhibition of mucus by 14%, CAT, 51% and SOD, 150%. Ranitidine afforded 56% prevention in ulcer formation with 67%, 55% and 78% attenuation of the inhibition of mucus, CAT and SOD, respectively, by indomethacin. While indomethacin-induced lipid peroxidation was attenuated by 58% reduction in MDA concentration on pretreatment with folic acid, Ranitidine offered 65% reduction. Basal and stimulated acid secretions were significantly reduced in the treated when compared with control animals. Folic acid produced a 21% reduction in the basal acid output when compared with the control animals (P < 0.05), and 140% reduction in histamine-induced acid response. CONCLUSION: The results indicate the gastroprotective activity of folic acid due its antioxidative and anti-secretory properties.

Analgesic activity of aqueous leaf extract of Phyllanthus amarus.

Various doses of the aqueous extract of Phyllanthus amarus (AEPA) were investigated for analgesic and anti-inflammatory activities using both thermal and chemical models of pain assessment in rats. The extract caused a significant (P < 0.05) dose related increase inhibition of the carrageenan-induced paw oedema in the rats. The inhibition produced by 200 mg/kg AEPA (70.20%) was significantly higher than that of the reference drug (Acetylsalicylic acid). The extract produced a marked analgesic activity by inhibiting both early and late phases of pain stimulus in Formalin-induced paw licking rats and also a significant and dose related increase in inhibiting the mean tail immersion duration (MITD) at varying water bath temperature (50 degrees C, 55 degrees C and 60 degrees C). This study thus established the anti-inflammatory and analgesic activities of Phyllanthus amarus.

Effect of Magnesium pre-treatment on alloxan induced hyperglycemia in rats.

BACKGROUND: The role of vitamins and mineral supplementation in the prevention of diabetes mellitus is not well elucidated. OBJECTIVE: The effect of prior administration of magnesium on alloxan induced diabetes was assessed in rats. METHODS: 36 Male albino rats were used for this study. The animals were divided into 6 groups of 6 animals each; group 1 was healthy control; groups 2 served as diabetic control. Animals in group 3 received magnesium (100 mg/kg) i.p one hour prior to alloxan (120 mg/kg) administration, group 4 were also received magnesium (150 mg/kg) i.p one hour prior to alloxan administration. Animals in group 5 received magnesium (100 mg/kg) i.p only; group 6 animals received magnesium (150 mg/kg) i.p only. Blood samples were obtained from all animals and plasma glucose levels were determined on Day 0 (prior to treatment), Day 2, Day 5, Day 7 and Day 10 after the commencement of treatment. RESULTS: There was significant increase (P<0.001) in plasma glucose values in the alloxan treated group when compared with the control values. There was also a significant increase (P<0.01) in plasma glucose levels in the magnesium-pretreated (100 mg/kg and 150 mg/kg) diabetic groups when compared with healthy controls whereas there was a significant reduction (P<0.01) in plasma glucose level when compared with the diabetic control. CONCLUSION: This study has shown that magnesium pretreatment may delay the onset and subsequently cause a reduction in hyperglycemia in alloxan induced diabetes. This effect of magnesium may be attributed to its role as a scavenger of highly reactive hydroxyl radicals generated through alloxan reactions, its potentiation of glutathione antioxidant production and its role as a calcium blocker.

Catecholamines inhibit gastric epithelial [RGM-1] cell proliferation via ß adrenoceptors.

Catecholamines have been implicated in the modulation of normal cell growth, exerting inhibitory or excitatory control depending on the cell type. However, there is a dearth of information on the role of adrenergic mediators in gastric cell proliferation. In the present study, the effects of adrenaline (ADR) and noradrenaline (NOR) on mucosal cell growth and the cell cycle were evaluated in vitro using a normal rat gastric mucosal cell line RGM-1. Cell proliferation was assessed using [3H]-thymidine incorporation and cell cycle patterns were determined by DNA labeling with propidium iodide and flow cytometric quantification. The expressions of adrenoceptors in RGM-1 were determined by Western blot. ADR (0.01 - 10µM) and NOR (0.01 - 10µM) inhibited the growth of RGM-1 cells in a concentration-dependent manner. Pre-treatment of cells with ADR and NOR also inhibited the proliferation stimulated by epidermal growth factor (EGF). Neither phentolamine (non-selective α-adrenergic blocker), methoxamine (α1-selective agonist) nor clonidine (α2-selective agonist) significantly affected the inhibition of cell proliferation produced by ADR and NOR. Propranolol (non-selective ß-adrenergic blocker) and butoxamine (selective ß2-adrenergic blocker) significantly (but not totally) reversed the inhibitory action of ADR on cell proliferation. Furthermore, procaterol (selective beta-2 agonist) but not dobutamine (selective beta-1 agonist) had effects similar to those produced by ADR and NOR. Exposure of RGM-1 cells to both ADR and NOR caused significant inhibition of the G1 - S cycle progression as evidenced by the higher percentage of the G0/G1 phase and a decreased S- phase. This effect was blocked by pre-treatment with propranolol but not phentolamine These results indicate that catecholamines inhibit the proliferation of RGM-1 cells probably partly through beta-2 receptors.

Anti-histaminic potential of fractions from Hedranthera barteri [(Hook F.) Pichon] root in laboratory rodents.

Hedranthera barteri, anti-inflammatory activity, anti-nociceptive activity, anti-histaminic activityL. (HB) is used in the treatment of painful conditions and oedema amongst its folkloric use. The hexane and ethyl acetate fractions of the root of H. barteri were investigated for anti-nociceptive and antiinflammatory properties and probable mechanism of action. Hot plate, tail flick, formalin-induced oedema and acetic acidinduced writhing tests were employed to investigate the anti-nociceptive activity while the anti-inflammatory activity was investigated using carrageenan-induced paw oedema. Anti-histaminic potential of HB root extracts on the rat peritoneal mast cells (RPMCs) was explored through pectrofluorometric method. The root was screened for its phytochemical components. The HB root contains alkaloids,cardenolides and saponins. HXHBR exhibited higher anti-inflammatory potentials (P <0.001). HXHBR dose-dependently (P <0.01) reduced the histamine release from the rat peritoneal mast cells which is comparable with a standard anti-histaminic drug, ketotifen. These results showed that EAHBR and HXHBR possess anti-nociceptive and anti-inflammatory activities, and suggested its mechanism of action through the inhibition of histamine, an inflammatory mediator, usually released during the early phase of allergic responses and chronic phase of inflammatory pain. Flavonoids, alkaloids and/or saponins present in HB root may be responsible for its anti-nociceptive and anti-inflammatory properties.

Anti-inflammatory activities of a kolaviron-inhibition of nitric oxide, prostaglandin E2 and tumor necrosis factor-alpha production in activated macrophage-like cell line.

Kolaviron (KV), a biflavonoid fraction from the seeds of Garcinia kola has been shown to posess antiinflammatory properties in animal models of inflammation. In this study, the effect of KV on carrageenan-induced paw edema was investigated in mice. Furthermore, the effects of KV on the production of the pro-inflammatory mediators- nitric oxide (NO) and tumor necrosis factor alpha (TNF-alpha) were examined in an activated macrophage-like cell lines, RAW 264.7 cells. Administration of KV prior to injection of carrageenan significantly reduced the paw inflammation in a dose-dependent manner. KV consistently inhibited in-vitro production of NO and secretion of TNF-alpha in a dose-dependent manner. In addition, KV reduced the production of PGE2 in LPS-stimulated macrophages. Viability of cells at all concentrations studied was unaffected as determined MTT [3-(4,5- dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide] cytotoxicity assay. These results suggest that KV has inhibitory effects on LPS-induced TNF-alpha, NO and PGE2 production.

Inhibition of acute experimental colitis by a crude extract and diets containing seeds of Garcinia kola (heckel).

The protective effect of Garcinia kola (GK) crude extract on acetic acid induced colitis in rats was investigated. Colitis, a form of inflammatory bowel disease (IBD) is characterized by inflammation of colon. The pathology in colitis includes disruption of crypt architecture, inflammation of crypts, frank crypt abscesses, and hemorrhage or inflammatory cells in the lamina propria. Since oxidative stress plays an important role in the etiology of Inflammatory Bowel diseases,and Garcinia kola (GK), have been shown to reduce oxidative stress in the rat stomach.The present study was designed to investigate the effects of Garcinia kola on ulcerative colitis (UC) induced by acetic acid. Albino rats were divided into five groups; Group one served as control, group two received Normal saline, group three received 2.5% ethanol while groups four and five were given 20mg/kg and 100mg/kg of crude extract of Garcinia kolarespectively. In another experiment, rats were fed for 2 weeks on normal rat diets but specially composed to contain 12.5%, 25% and 50% by weight of G kola. Colitis was induced by intra-rectal administration of 6% acetic acid. The colonic damage was elucidated by macroscopic damage scores; colon wet weight, stool consistency and colonic edema (thickness of the colon). Intra-luminal administration of 6% acetic acid resulted in observable clinical and macroscopic signs of colitis.Pre-orally administered of crude extract of GK significantly reduced the colonic damage score (p<0.001), colon weight (p<0.001), thickness of the colon (p<0.001) and diarrhea (p<0.001).Histological examinations also indicated a marked reduction in tissue injury and inhibition in neutrophil infiltration in rats pretreated with crude extract of Garcinia kola. Results of this investigation provide experimental evidence of Garcinia kola as an anti-colitis agent.

Pretreatment effect of magnesium on alloxan induced hyperglycemia in rats.

The role of vitamins and mineral supplementation in the management of Diabetes mellitus is not well elucidated. We therefore carried out a preliminary study to assess the effect of prior administration of Magnesium on induction of alloxan diabetes, a model of type 1 diabetes mellitus. Twenty Male albino rats were used for this study. The animals were divided into 4 groups of 5 animals each. Animals in group 1 were normal rats and were not given any treatment, these served as healthy control. Animals in group 2 were diabetic rats that were not given any treatment, they served as diabetic control. Animals in group 3 were treated with magnesium (100mg/kg) intraperitoneally one hour prior to alloxan (150mg/kg) administration. Animals in group 4 were given intraperitoneal injection of magnesium (100mg/kg) once, and blood samples were obtained one hour after administration. Blood samples were obtained from all animals after 48 hours and plasma glucose levels determined using the glucose oxidase method. There was significant increase (p<0.001) in plasma glucose level in the alloxan treated group when compared with the control. There was also a significant increase (p<0.01) in magnesium-pretreated diabetic group. However, there was a significant reduction (p<0.01) in blood glucose level 48 hours after alloxan administration in the magnesium pre-treated diabetic group when compared with the diabetic controls. Magnesium pretreatment may delay the onset of alloxan induced hyperglycemia and this may be due to the scavenging effect of magnesium on the highly reactive hydroxyl radicals (OH) which was generated through alloxan reaction.

Onion (Allium cepa) extract prevents cadmium induced renal dysfunction.

Cadmium (Cd), a heavy metal, is known for its adverse effects on the body. In this study, the lowering effect of Cd on renal clearance (RC) was investigated, and Allium cepa extract (AcE) (an antioxidant) was pre-administered orally to prevent Cd's adverse effects. Seventy-two Wistar rats, grouped into three (n = 24), were used for this study. While Group C was given 1.0 ml of AcE daily (orally), Group A and Group B were given distilled water. AcE administration was done for eight weeks. Afterwards B and C were then given 1.5 ml/kg BW of 0.3 mg/L 3CdSO(4).8H(2)O intraperitoneally for three consecutive days. The results obtained showed that Cd causes significant reduction in the 24 hour urine volume (from 3.017 +/- 0.125 to 2.433 +/- 0.118 ml), RC (from 3.258 +/- 0.114 to 1.357 +/- 0.104 ml/h for creatinine; and from 0.350 +/- 0.057 to 0.185 +/- 0.055 ml/h for urea), plasma and tissue SOD and CAT activity (form 1.644 +/- 0.036 to 1.307 +/- 0.056 u/g protein for plasma SOD; 0.391 +/- 0.029 to 0.2692 +/- 0.031 u/protein for plasma CAT; 1.695 +/- 0.034 to 1.327 +/- 0.049 u/g protein for tissues SOD; and from 0.350 +/- 0.027 to 0.273 +/- 0.043 u for tissue CAT), and significant MDA increased in plasma (from 1496.79 +/- 1.321 to 1679.48 +/- 143.29 mug/g protein) and tissue (from 1265.22 +/- 2.285 to 1669.87 +/- 14.61 mug/dL). AcE, however, prevents these Cd's adverse effects. This findings lead to the conclusion Cd exposure causes renal dysfunction, but oral administration of onion could prevent it.

Effects of amodiaquine hydrochloride and artemisinin on indomethacin-induced lipid peroxidation in rats.

In this study, the effects of two antimalarials-amodiaquine hydrochloride and artemisinin were investigated in ulcerated albino rats of Wistar strain. Rats were treated with amodiaquine (30 mg kg(-1)) and Artemisinin (2.86 mg kg(-1)) for 24 h after formation of ulcers induced by indomethacin. Treatments with Amodiaquine Hydrochloride led to significantly increased gastric lesions while artemisinin led to significantly decreased gastric lesions. Also, amodiaquine hydrochloride seemed to elaborate the indomethacin induced effects on gastric juice volume, pH and acid output, while artemisinin attenuated these changes. The data indicates that the use of amodiaquine hydrochloride may be dangerous to the integrity of the stomach, especially in existing gastric ulcers, while artemisinin is mild and ameliorating, may result from their lipid peroxidation/apoptosis activity interference.

Attenuation of indomethacin- and HCl/ethanol-induced oxidative gastric mucosa damage in rats by kolaviron, a natural biflavonoid of Garcinia kola seed.

Reactive oxygen species (ROS) have been implicated in the aetiology of HCl/ethanol- and indomethacin gastric mucosal damage. This study investigated the protective effects of kolaviron, a natural antioxidant from the seed of Garcinia kola, on oxidative gastric mucosal damage induced by HCl/ethanol, and indomethacin.A HCl/ethanol mixture (1.5 mL of 0.15 n HCl in 70% ethanol) and indomethacin (IND) caused severe gastric damage with an ulcer index of 2.90 +/- 0.8 and 2.5 +/- 0.4, respectively, and significant reductions in the gastric mucosal content of catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH) (p < 0.001).Pre-treatment of animals with kolaviron (100 mg/kg) orally 1 h and once daily for 3 days prior to ulcer induction significantly reduced the formation of ulcers induced by HCl/ethanol with preventive ratios of 65 and 72, respectively, while rats treated with kolaviron 1 day and for 7 days prior to IND treatment attenuated ulcer formation by 59% and 77%. Pre-treatment with ranitidine 1 h prior to ulcer induction (50 mg/kg) elicited preventive ulcer ratio of 55. Kolaviron pre-treatment 1 h before ulcer induction attenuated the HCl/ethanol reduction in CAT, SOD and GSH by 43%, 42% and 30%, respectively, and 67%, 68% and 64% following 72 h treatment with kolaviron. Ranitidine elicited 24%, 41% and 29% protective effects, respectively.Similarly, kolaviron administered to rats 1 day and for 7 days before IND treatment attenuated the drug-induced inhibition of CAT by 44% and 70%; SOD by 23% and 43% and GSH by 32% and 55%, respectively. In a 1 h and 3-day treatment with kolaviron before HCl/ethanol administration, MDA was reduced by 35% and 55%, respectively, while kolaviron administration 1 day and for 7 days before IND elicited a 39% and 58% reduction in MDA. Ranitidine elicited 39% and 50% reduction in MDA following HCl/ethanol and IND treatment. The results indicate the gastroprotective activity of kolaviron, which may be linked to its intrinsic antioxidant properties.

Catecholamines potentiate the effect of thyroid hormone on intestinal absorption of glucose in the rat.

The study is to investigate the role of catecholamines on the increased absorption of glucose from the gut by thyroxine, the effect of graded doses of adrenaline and noradrenaline on glucose absorption was studied in euthyroid (ET), hyperthyroid (TH-) and hypothyroid rats (Thx). Glucose absorption was deduced in vivo from intestinal segment perfused with Kreb's bicarbonate solution containing 5.6 mM glucose and in vitro using the everted sac technique. In vivo, basal glucose absorption was significantly increased in the hyperthyroid and decreased in the hypothyroid rats (1.97 +/- 0.19 mM/g, P<0.01, and 0.92 +/- 0.10 mM/g, p<0.05 respectively) when compared with the euthyroid group (1.34 +/- 0.15 mM/g). Adrenaline (20 mg/dl - 80 mg/dl) increased glucose absorption in a dose dependent manner in all the groups. However, the responsiveness of the gut glucose absorption to adrenaline (as evidenced by the dose producing half- maximal absorption or ED50) was reduced by thyroidectomy (ED50 = 26.09 mg/100 ml) and increased by chronic thyroxine treatment (ED50 = 11.13 mg/100 ml). The ED50 in the euthyroid animals was 14.6 mg/100 ml. In vitro, glucose absorption from the isolated segments in both Thx and TH- rats were significantly reduced (P<0.05). Incubation of the isolated intestinal segments with graded doses of adrenaline caused a significan and dose related increases in glucose absorption. However thyroidectomy shifted the dose-response curve for glucose uptake from the isolated intestinal sac incubated with adrenaline to the right of the curve for euthyroid rats. It is concluded that catecholamines may play a role in the increase in intestinal absorption by thyroid hormones.

Blastocyst implantation: effect of thyroidectomy and thyroxine replacement in the rat.

The long term effects of thyroidectomy and chronic thyroxine treatment on blastocyst implantations in female albino rats were studies. Implantation was delayed in both thyroidectomized and hyperthyroid rats, as there was no evidence of blastocyst implantation on day 6 of pregnancy. By day 9, when signs of implantation were observed, the number and weights of the implantation sites were significantly reduced in the athyroid and hyperthyroid rats. Both thyroidectomy and chronic thyroxine treatment significantly reduced the fetal sites and increased the incidence of resorptions when compared with the control. It is concluded that a functional thyroid gland is required for normal implantation to occur.

Predictors of academic performance in the pre-clinical sciences: effects of age, sex and mode of admission at the Maiduguri Medical School.

The effect of age on admission, sex and mode of admission as correlates of academic performance in the final pre-clinical examination was investigated. Records of 222 medical students covering five academic years (1987-1992) were obtained and matched for each student with the result of the final pre-clinical examinations in Anatomy, Physiology and Biochemistry. Age significantly affected students' performance as those below 20 years and those above 24 years performed better than those with ages between 20 and 24 years. A higher proportion of the male medical students were successful in all the three subjects when compared with females. Medical students admitted through the Joint Matriculation Examination performed better than those admitted through the remedial science and direct entry programmes. The implications of these findings are discussed.