Toxic substances in pulses

Deleterious substances of various kinds are present in legume grain eaten by man. Among them are:

1. Trypsin inhibitors
2. Cyanogenic glucosides
3. Goitrogenic factors
4. Hemagglutinins/Haemagglutinins
5. Saponins
6. Alkaloids
7. Tannins
8. flatulent factors
9. Antivitamins
10. Aflatoxin

Contamination with microorganisms could result in the formation of toxins (aflatoxin) which produce adverse effects when ingested.

In most pulses these toxins are destroyed by adequate soaking, removal of the skin and ordinary methods of cooking. In some species removal of the skin and inactivation toxins require prolonged cooking time, pressure cooking or autoclaving, facilities that are available in few households. For any pulse to welcome in a household it should lend itself to ordinary methods of preparation, needing little fuel. Pulses form such an important item of the diet in developing countries that every effort should be made to encourage their consumption by increasing their digestibility.

In the preparation of whole grains, the seeds should be soaked for 24 to 36hoursin a small volume of water, changing the water every 8 to 12 hours. Skins can be removed by rubbing the seeds gently. The grain is then boiled in a little water till it softens. The cooking water should be consumed as it contains water soluble nutrients. When feeding young children, the seeds should be mashed to increase the digestibility. The dhal is more easily cooked than gram. Pulses are the one food that benefits by over boiling.

What are phytohaemagglutinins?

Introduction

Haemagglutinins are proteins capable of agglutinating red blood cells. Such substances present in plants are called phytohaemagglutinins. They are present in all legumes. About 25% of the growth inhibition produced in rats (experiment level) by Soya beans is due to haemagglutinins. Significant level of haemagglutinins occur also in black beans and kidney beans (varieties of Phaseolus vulgaris).purified hemagglutininsfrom these two pulses, when fed to rats at a level0.5 to 1% result in 100% mortality within two weeks.

Mechanism of toxicity

Phytohaemagglutinins bind with the red cell membrane and makethem more vulnerable to the hemagglutination

Common food items containing phytohaemagglutinins

Soya bean

Black beans and

Kidney beans

Removal of phytohaemagglutinins from those food items

The toxic factor can be destroyed completely by soaking the grain overnight and later autoclaving.

The importance of such factors in human nutrition should not be discounted, as pulses form an important item in most diets.

ACTH stimulation test

Introduction

The anterior pituitary is often referred to as the “master gland” because, together with the hypothalamus, it orchestrates the complex regulatory functions of multiple other endocrine glands. The anterior pituitary gland produces six major hormones: (1) prolactin (PRL), (2) growth hormone (GH), (3) adrenocorticotropin hormone (ACTH), (4) luteinizing hormone (LH), (5) follicle-stimulating hormone (FSH), and (6) thyroid-stimulating hormone (TSH)

ACTH secretion is pulsatile and exhibits a characteristic circadian rhythm, peaking at 6 A.M. and reaching a nadir about midnight. Adrenal glucocorticoid secretion, which is driven by ACTH, follows a parallel diurnal pattern.

ACTION

The major function of the HPA axis is to maintain metabolic homeostasis and to mediate the neuroendocrine stress response. ACTH induces cortical steroidogenesis by maintaining adrenal cell proliferation and function. The receptor for ACTH, designated melanocortin- 2 receptor, is a GPCR that induces steroidogenesis by stimulating a cascade of steroidogenic enzymes

LABORATORY INVESTIGATION

Biochemical diagnosis of pituitary insufficiency is made by demonstrating low levels of trophic hormones in the setting of low target hormone levels. The diagnosis of adrenalInsufficiency may be established by means of an ACTH stimulation test.

Test

This is a screening test (the so-called rapid ACTH stimulation test) which involvesthe administration of 25 units (0.25 mg) of cosyntropin intravenously or intramuscularly and measurement of plasma cortisol levels before administration and 30 and 60 min after administration, the test can be performed at any time of the day. The most clear-cut criterion for a normal response is a stimulated cortisol level of >500 nmol/L (>18 µg/dL), and the minimal stimulated normal increment of cortisol is >200 nmol/L (>7 µg/dL) above baseline. Severely ill patients with elevated basal cortisol levels may show no further increases following acute ACTH administration.

CPK (creatine phosphokinase) test

Introduction

CK is a molecule made up of two polypeptide subunits (M and B) coded by different genes. Three major isoenzymes are available.

• CK-MM is the major isoenzyme type available. This is present in skeletal and cardiac muscles

• CK-MB is the isoenzyme which is primarily found in the cardiac muscles. A small amount is present in the skeletal muscles as well.

• CK-BB is the isoenzyme which is mainly found in the brain matter. A small amount is also found in kidney, stomach, colon, and liver as well.

MM is the predominant CK type. Serum of a normal individual contains more than 97% of MM variety whereas rest consists of MB type. Normal CK level is 200-250 u/l There are several causes which can lead to the elevation of CK level in the blood .These include;

1. Artefactual causes ( Hemolysis)

2. Physiological causes(neonates, adult male> adult female, exercise)

3. Pathological causes (e.g. shock & circulatory failure, Myocardial infarction, muscular dystrophy, Rhabdomyolysis, Hypothyroidism, Alcoholism, Head injury and strokes)

Importance in cardiac injuries

Most important aspect of the CK is it’s relevant with cardiac injury. The level of CK rises within 4 to 8 hours after the cardiac event and it returns to normal level by 48 to 72 hours. The peak level can be detected within 16 to 24 hours after the event. The main drawback of measurement of CK level is its lack of specificity for cardiac injuries as it elevates in above mentioned causes as well.

Since the CK-MB is more specific for the cardiac muscle, measurement of CK-MB level can be useful. But the skeletal muscles also contain some amount of CK-MB, which is very small when compare with the amount containing in the cardiac muscles (Table A). Usually in serum the fraction of CK-MB is about 3%. If this fraction is higher than the normal level it will indicate the cardiac injury. But sever skeletal muscles damage can give rise to the higher level of CK-MB therefore sever skeletal muscles damage can mimic acute myocardial infarction. To avoid this false positive scenario, series of ECG should be done with the measurement of CK level. There are some other causes which lead to the rise in CK-MB level such as crush syndrome, Major surgery, Defibrillation and Malignant Hyperthermia.

Table A

Isoenzyme	% in heart muscles	% in cardiac muscles
CK-MM	78	98
CK-MB	22	2

Following condition give elevated CPK level

1. Hyperthermia

2. Necrotizing fasciitis caused by S. pyogenes

3. Legionnaires’ disease (Pneumonia)

4. Severe Leptospirosis (Weil’s Syndrome)

5. Complications of influenza infection

6. Crimean-congo hemorrhagic fever

7. Trichinellosis

8. Cardiogenic shock

9. Hypothyroidism

10. Hypophosphatemia

11. As a side effects of HMG-CoA reductase inhibitors

12. As a side effects of Antipsychotic medications