Daniel Antwi | University Of Ghana, Accra,Legon (original) (raw)

Papers by Daniel Antwi

Medical Science Monitor International Medical Journal of Experimental and Clinical Research, Mar 17, 2003

The purpose of this study was to ascertain the effect of Losartan, a non-peptide angiotensin II r... more The purpose of this study was to ascertain the effect of Losartan, a non-peptide angiotensin II receptor antagonist used for the treatment of hypertension, on the movement of proteins and fluids across the vascular compartment in ischemic cat brains. The experiments were carried out on anesthetized cats under artificial ventilation and autohemoperfusion of the brain with a stable volume of blood with the help of a resistograph. Cerebral ischemia was induced by a 15-minute arrest of the autohemoperfusion pump, tying various anastomoses in the neck region, and reducing arterial pressure to 40-30 mm Hg by hemorrhage with subsequent reinfusion of the lost blood. In the postischemic period in the cat brain, control experiments showed the onset of metabolic acidosis and an increase in permeability of the brain capillaries to fluids and protein molecules. Intravenous introduction of losartan, an angiotensin II receptor antagonist, at a dose of 3 mg x kg(-1) 10 minutes into the postischaemic period, enhanced the normalization of metabolic and transcapillary exchange. Thus vector permeability was reversed from blood-to-tissue in the control situation (without losartan) to tissue-to-blood during losartan administration. The results provide strong evidence that losartan may play a role in preventing cerebral edema, and that the renin-angiotensin system plays an important role in postischemic cerebrovascular events.

Journal of Biological Chemistry

Background of Study: The Kalanchoe genus is a succulent perennial plant belonging to the class Br... more Background of Study: The Kalanchoe genus is a succulent perennial plant belonging to the class Bryophyllum. It thrives at temperate areas of the world. In Africa, over 200 species have being identified and many of these species have been used medicinally especially Kalanchoe pinnata and Kalanchoe integra in Ghana for the treatment of various ailments. Aim/Objective: To evaluate the safety of the aqueous extract of the fresh leaves of K. integra during a single oral high dose of 5000 mg/kg b.wt in ICR mice, a study conducted by the fixed dose method. Research methodology: Freshly prepared aqueous leave extract were strained using muslin and freeze-dried, reconstituted and administered to ICR mice of either sex (21-25 g). The animals were kept under standard conditions and experimental procedure conducted in accordance with animal research guidelines. Blood samples for biochemical analysis were obtained by cardiac puncture. Gross and histopathological examinations were performed and s...

Ghana medical journal

To report on the proportions of restrictive, obstructive and combined types of respiratory diseas... more To report on the proportions of restrictive, obstructive and combined types of respiratory diseases in patients referred to respiratory units at the Korle Bu Teaching Hospital. This was a retrospective study of lung function test (LFT) data on patients who were referred from clinics both in and outside KBTH. A spirometer was used to assess various lung volume parameters. One quarter of total subjects (25.5%) had obstructive, 14.8% restrictive and 11.7% exhibited combined forms of respiratory disease. The rest showed none of the above conditions and were classified as normal. We also found differences in proportions of the disorders for subjects in different age and weight categories. Whereas obstructive respiratory disease occurred more in obese patients, and patients who were 35 years and above, restrictive and combined respiratory diseases occurred more in underweight patients, and patients below age 35 years. The respiratory diseases suggested in our study were found not to be se...

The American journal of physiology

Using immunoblot analysis, we examined the electrophoretic mobility of glycogen synthase from rat... more Using immunoblot analysis, we examined the electrophoretic mobility of glycogen synthase from rat skeletal muscle and adipose tissue. Extracts from muscle freeze clamped in situ contained at least three forms of synthase with different electrophoretic mobilities. Extracts from adipose tissue also contained multiple forms but lacked the form with greatest mobility found in the muscle extracts. Phosphorylation at multiple sites of glycogen synthase is known to deactivate the enzyme and retard its electrophoretic mobility in sodium dodecyl sulfate gels. These results suggest that there is very little or no dephosphorylated glycogen synthase in adipose tissue and that phosphorylated forms of glycogen synthase synthesize adipose tissue glycogen. Relative to control, it is known that fasting decreases and refeeding increases glucose incorporation into glycogen in rat epididymal adipose tissue but not skeletal muscle incubated in vitro in the presence of insulin. Fasting did not change the...

Medical science monitor : international medical journal of experimental and clinical research, 2003

Journal of the Ghana Science Association, 2001

ABSTRACT Studies have shown that while injections of insulin cause an increase in fat mass, infus... more ABSTRACT Studies have shown that while injections of insulin cause an increase in fat mass, infusions of insulin increase fat mass. The aim of this paper was to test the hypothesis that if an increase in glycogen is an indicator of an impending increase in adipose mass, then insulin infusions should not increase glycogen, while insulin injections should. Normal rats were treated with insulin (or saline in control group) either by intraperitoneal injection or by tail vein infusion. In agreement with previous evidence, insulin injections increased glycogen in adipose tissue significantly within 12 hours of injection. In contrast to injections, insulin infusions failed to increase glycogen in rat adipose tissue. This report concludes that adipose tissue glycogen is a prelude to an increase in the size of adipose tissue. (Journal of the Ghana Science Association: 2001 3(3): 1-6)

International Journal of Gynecology & Obstetrics, 2012

Discovery and Innovation, 2005

... in stroke-prone spontaneously hypertensive rats (Asiedu-Gyekye and Antwi, 2003; Blezer et al.... more ... in stroke-prone spontaneously hypertensive rats (Asiedu-Gyekye and Antwi, 2003; Blezer et al., 2001) while Asiedu-Gyekye and Gaevy ... Determination of cerebral oxygen consumption In determining the oxygen consumption by the brain, the blood gas tension of oxygen and ...

Background: Ankle-brachial index (ABI) and indices of obesity are both use to indicate cardiovasc... more Background: Ankle-brachial index (ABI) and indices of obesity are both use to indicate cardiovascular risk. However, association between body composition indices and ABI, a measure of peripheral arterial disease, is inconsistent in various study reports. In this study, we investigated the relationship between ABI and general and central indices of obesity in Ghanaians without history of cardiovascular diseases.

Background: Diabetes and hypertension increase arterial stiffness and cardiovascular events in al... more Background: Diabetes and hypertension increase arterial stiffness and cardiovascular events in all societies studied so far; sub-Saharan African studies are sparse. We investigated factors affecting arterial function in Ghanaians with diabetes, hypertension, both or neither.

Background. Increased arterial stiffness is an independent cardiovascular risk factor in diabetes... more Background. Increased arterial stiffness is an independent cardiovascular risk factor in diabetes patients and general population. However, the contribution of diabetes to arterial stiffness is often masked by coexistent obesity and hypertension. In this study, we assessed arterial stiffness in nonhypertensive, nonobese type 2 diabetes (T2DM) patients in Ghana. Methods. In case-control design, 166 nonhypertensive, nonobese participants, comprising 96 T2DM patients and 70 nondiabetes controls, were recruited. Peripheral and central blood pressure (BP) indices were measured, and arterial stiffness was assessed as aortic pulse wave velocity (PWVao), augmentation index (AIx), cardioankle vascular index (CAVI), and heart-ankle pulse wave velocity (haPWV). Results. With similar peripheral and central BP indices, T2DM patients had higher PWVao (8.3 ± 1 versus 7.8 ± 1.3, í µí± = 0.044) and CAVI (7.9 ± 1.2 versus 6.9 ± 0.7, í µí± = 0.021) than nondiabetic control. AIx and haPWV were similar between T2DM and nondiabetic controls. Multiple regression models showed that, in the entire study participants, the major determinants of PWVao were diabetes status, age, gender, systolic BP, and previous smoking status (í µí»½ = 0.22, 0.36, 0.48, 0.21, and 0.25, resp.; all í µí± < 0.05); the determinants of CAVI were diabetes status, age, BMI, heart rate, HbA1c, total cholesterol, HDL cholesterol, and previous smoking status (í µí»½ = 0.21, 0.38, 0.2, 0.18, 0.24. 0.2, −0.19, and 0.2, resp.; all í µí± < 0.05). Conclusion. Our findings suggest that nonhypertensive, nonobese T2DM patients have increased arterial stiffness without appreciable increase in peripheral and central pressure indices.

Background: Impaired angiogenesis is amongst the underlining mechanisms of organ damage in diabet... more Background: Impaired angiogenesis is amongst the underlining mechanisms of organ damage in diabetes and hypertensive patients. In diabetes and hypertensive patients without proteinuria and overt CVDs, we studied the levels of angiogenic growth factors, angiopoietin (Ang)-1, Ang-2 and vascular endothelial growth factor (VEGF), and the relationship between these angiogenic growth factors and renal function, measured as estimated glomerular filtration rate (eGFR).

Metabolism, 1986

The oral hypoglycemic agent, ciglitazone, ~5-[4-~1-methylcyclohexylmethoxy)benzyl]-thiazolidine-2... more The oral hypoglycemic agent, ciglitazone, ~5-[4-~1-methylcyclohexylmethoxy)benzyl]-thiazolidine-2,4-dione~, was fed for nine days to genetically obese (ob/ob) mice aged 5 to 6 weeks. This treatment resulted in a lowering of plasma glucose and circulating insulin levels, but did not cause a fall in plasma corticosterone levels. Basal 2-deoxy-D-glucose uptake by the perfused hindquarters of ob/ob mice was unchanged by ciglitazone feeding. In the presence of 0.1 mU/mL insulin in the perfusion medium, there was a significant increase in the uptake rate of 2-deoxy-D-glucose by the skeletal muscle of ciglitarone-treated ob/ob mice, while there was no insulin effect in untreated ob/ob mice. Insulin at a concentration of 1 mU/mL caused a further stimulation of 2-deoxy-D-glucose transport. However, this response was significantly lower than the maximal stimulation in lean mice. Ciglitazone feeding did not have any effect on [5-3H]-glucose metabolism by the perfused muscle which remained subnormal, suggesting that the posttransport metabolism of glucose was limited by substrate availability. In the perfused mouse liver, net ['%I-glucose production from ['%I-lactate was unchanged by ciglitazone treatment while gluconeogenesis from ['%I-alanine was reduced. These findings show that ciglitazone produces its hypoglycemic effect by improving the insulin sensitivity in skeletal muscle, as others have reported in the adipose tissue. The presence of elevated plasma levels of corticosterone and lower levels of insulin in ciglitarone-treated ob/ob mice suggests that the adrenal glucocorticoids are responsible for the basal defects in glucose transport and the hyperinsulinemia is responsible for the insulin insensitivity.