TABLE OF CONTENTS
CHAPTER ONE
1.0
INTRODUCTION
1.1 BACKGROUND OF STUDY
1.2 STATEMENT OF PROBLEM
1.3 SIGNIFICANCE OF STUDY
1.4
AIM OF THE STUDY
1.5
OBJECTIVE OF THE STUDY
CHAPTER TWO
2.0 LITERATURE
REVIEW
2.1 MEAT: LEVELS OF CONSUMPTION
2.2 STEROID
HORMONES
2.3 USE
OF STEROID IN ANIMAL HUSBANDRY
2.4 DEXAMETHASONE
2.5 CHOLESTEROL
2.6 TRIGLYCERIDES
2.7 LOW
DENSITY LIPOPROTEIN
2.8 HIGH
DENSITY LIPOPROTEIN
2.9 HEALTH
IMPLICATION OF ABNORMAL LEVELS IN LIPID PROFILE
2.10
HEALTH IMPLICATION OF STEROID USED IN
ANIMAL HUSBANDRY
CHAPTER THREE
3.0 MATERIALS
AND METHODS
3.1 SAMPLE
COLLECTION
3.4 DETERMINATION
OF LIPID PROFILE
CHAPTER FOUR
4.0
RESULTS
4.1
STEROID DETERMINATION
CHAPTER FIVE
DISCUSSION
CONCLUSION
APPENDICES
APPENDIX V
APPENDIX VI
APPENDIX VII
STANDARD CALIBRATION CURVE
APPENDIX VIII
CHAPTER ONE
1.0
INTRODUCTION
1.1 BACKGROUND OF STUDY
Hormones are chemicals produced by animals to
co-ordinate their physiological activities. They acts as messengers, produced
in and released from one kind of tissue to gradually stimulate or inhibit some
process in a different tissue over a long period. The importance of individual
hormones varies between sexes and age and a disruption of the endocrine
equilibrium may result in multiple actions e.g the male hormone testosterone
controls many processes from the development offoetus to libido in the adult. Alternatively,
one function may be controlled by multiple hormones, e.g. the menstrual cycles
involves estradiol, progesterone, follicle stimulating hormone and luteinizing
hormone. Hormones are vital innormal development, maturation and physiological
functioning of many vital organs and processes in the body (Annamaria, 2012).
However, like any other chemicals of natural or
synthetic origin, hormones may be toxic to living organisms under certain
circumstances. The toxicity may be due to an excess of its normal
(physiological) action. Hormones, like other chemicals, may also exert direct
toxic actions not related to their endocrine (physiological) actions
(Annamaria, 2012).
Besides the endogenous corticosteroids (cortisol,
cortisone) and those suspected to be endogenous (prednisone, prednisolone),
there are synthetic exogenous corticosteroids (dexamethasone, betamethasone),
developed because of their anti-inflammatory properties.
Estrogens,
androgens, gestagens and corticosteroids are steroids which act as hormones.
The parent compound from which all steroids are derived is cholesterol. The
classification of steroid hormones can be done according to their biological
activity and pharmacological effects which includes the sex steroids, a subset
of hormones producing sex differences and reproduction such as estrogen,
gestagens and androgens. The second group is the corticosteroids which are
glucocorticosteroids, involves in metabolism and immune function and
mineralocorticosteroids, involves in the regulation of the blood volume and
electrolyte content.
They can also be classified upon their endo or
exogenous origin. Steroid hormones that are biosynthetically present in the
body are the endogenous hormones and they are chemical messengers from one cell
(or group of cells) to another e.g (estradiol). Exogenous steroids are also
called xenobiotics are foreign compounds that are naturally or synthetically
produced e.gmethyltestosterone (Noppeet
al., 2008).
Apart from the endogenous corticosteroids
(cortisol, cortisone) and those suspected to be endogenous (prednisone,
prednisolone), there are the synthetic exogenous corticosteroids ‘old’
structures. Well-known examples of these drugs with a steroids structures are
tetrahydrogestrinone (THG), norbolethoneanddesoxymethyltestosterone (DMT) (Noppeet
al., 2008).
Cholesterol is a waxy
substance made by animal liverand also supplied in diet through animal products
suchas meats, poultry, fish and dairy products. Cholesterol isneeded in the
body to insulate nerves, make cellmembranes and produce certain hormones, and
it is animportant lipid in some membranes. However, the bodymakes enough
cholesterol, so any dietary cholesterol
isn'tneeded. Cholesterol plays
a major role in human heart health but can be both good and bad. High-densitylipoprotein
(HDL) is good cholesterol and low-density lipoprotein (LDL) is bad cholesterol.
Triglycerides are another fat in the
bloodstream, the most common type of fat in the body. High levels
oftriglycerides is also linked to heart disease and diabetes.A high
triglyceride level combined with low HDL cholesterol or high LDL cholesterol
seems to speed up atherosclerosis, which is the buildup of fatty deposits in
artery walls that increase the risk for heart attack and stroke (Hongbao,
2006).
1.2 STATEMENT OF PROBLEM
Due to the important role of hormones in several body
functions, they also have been exogenously applied to animals and humans for
productivity and growth development. Focusing on the veterinary field, due to
the obvious ability to improve weight gain and feed efficiency in meat
producing animals, natural hormones and/or the synthetic surrogates have been
used in agricultural practice for several decades by farmers and this imposes
several risks on human health. Also, corticosteroids can be illegally used in
animal fattening, this is because it has been described that they may have a
synergetic effect when combined with anabolic steroids or agonists. (Courtheynet al., 2002; Noppeet
al., 2007).
Both exogenous hormones and synthetic compounds
mimicking their effects may change the endogenous balance of human body,
disturbing their natural functions. Children are extremely sensitive to
exogenous steroid hormones because of their low endogenous levels, small
variation in their blood levels might trigger serious pubertal development
effects and even future adult life problems (Aksglaedeet al., 2006; Alveset al.,
2007). An unexpected advance in timing of puberty in both African-American and
white American girls (Herman-Giddenset al.,
1997).
In adults, an association between the risk of breast
cancer and persistently elevated blood levels of oestrogen and androgen has
been found in many studies (Kaakset al.,
2005; Yager& Davidson, 2006). Also, data published by Swan et al., in 2007 suggested that maternal
beef consumption may alter males’ testicular development in utero and adversely
affect his adult reproductive capacity.
In the human diet, meat is
seen as a major source of fat and especially of saturated fatty acids (SFAs),
which havebeen implicated in diseases associated with modern life,mostly in
developed countries. Coronary heart diseaseand arteriosclerosis are among the
most importantcauses of human mortality, and are strongly associatedwith
dietary intake of cholesterol and saturated fatty acids(Simopoulos, 2002,
2004). In addition, HDL is considered to be beneficial as higher levels have been
correlated with reduced risk of negative cardiovascular event (American heart
Association, 2007). Elevated LDL and triglycerides are considered detrimental
as their increased concentration is well is well correlated with poor
cardiovascular outcomes (American heart Association, 2007; Segrest, 2002).
1.3 SIGNIFICANCE OF STUDY
As regards to hormonal content, all foodstuff of
animal origin contains steroids hormones and metabolites, but their
concentrations vary with the kind of food, gender, age and physiological stage
of the animal. (Daxenbergeret al.,
2001; Poelmanset al., 2005a, 2005b).
In fact meat is clearly one of the most naturally contaminated foods. (Maumeet al., 2001, 2003; Poelmanset al., 2005a). Regarding potential
toxicological substances used in animal husbandry and their derivatives the US
Food and Drugs Administration (FDA) concluded that ‘safety can be assured’
because they are endogenous in both food-producing animals and people.
However, to show the safety of an endogenous sex
steroid, it should be demonstrated under the proposed conditions of use, the
concentration of residue of the endogenous steroid in treated food-producing
animals is such that the increase will not exceed this 1% permitted increase.
In 1988, the Joint Food and Agricultural Organisation/World Health Organisation
(FAO/WHO) Expert on Food Additives (JECFA) and the US Food and Drugs
Administration (FDA) that the residues found in meat from treated animals were
safe for the consumers.
The World Health Organization recommends
that the daily fat intake be reduced to 30% of the total energy intake, and
that saturated fats should be limited to 10% of this caloric intake. It is also
advised that cholesterol intake should not exceed 300 mg per day. Dietary
intake of unsaturated fatty acids (UFA) has been shown to reduce the risk of
cardiovascular diseases (CVD) and possibly the incidence of some cancers,
asthma and diabetes among others. In fact, clinical trials have shown that it
is unnecessary to completely substitute fish or poultry for lean red meat
choices to achieve desirable blood lipid profiles (Davidson et al., 1999; Hunninghakeet al., 2000).
The concentration of dexamethasone will
be analyzed in order to know if the use its use is being abused in animal
husbandry by local farmers and the residual concentration in meat matrix will
be known at the end of this study. The lipid profile of the selected animals will
also be determined.
1.4
AIM OF THE STUDY
To identify the health implication of steroid fattened
livestockin Lagos market and the implication of their lipid profile for human
nutrition.
1.5
OBJECTIVE OF THE STUDY
1. To determine the presence of dexamethasone (steroid)
in blood samples of chicken, mutton, pork, chevon and beef.
2. To determine the Lipid profile (cholesterol,
triglyceride, high density lipoprotein (HDL), low density lipoprotein (LDL) of
the blood samples of the above named meat samples.
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