Impact analysis of lead, copper and zinc content in selected African indigenous and exotic vegetables from Nairobi markets, Kenya

Vegetables consumed in urban sites can be contaminated with harmful metal levels absorbed from planting sources because metals are commonly present in soil. The present study was carried out to evaluate Pb, Cu and Zn concentration in ten of the commonest vegetables in Nairobi markets. Vegetables were collected from 15 markets in urban and peri-urban Nairobi and analyzed for metal content using an Atomic Absorption Spectrophotometer (AAS). The concentrations were in the order Zn > Cu > Pb with values of 15.6 to 120, 0 to 19 and Pb 0 to 1.37 mg/kg, respectively. There were significant differences in markets and within vegetables (p<0.05). Sources were not consistent in the levels of metals indicating that they were supplied from different planting sites. Cu and Zn were within permissible consumer limits while Pb in many vegetables exceeded the limit. Continuous control of pollution and evaluation of metal content in vegetables is recommended in monitoring environmental contamination and food safety.Key words: African indigenous vegetables, heavy metals, pollution, urban and peri - urban markets

Heavy metal content of selected African leafy vegetables planted in urban and peri-urban Nairobi, Kenya

African indigenous vegetables planted along Nairobi Rivers are suspected to absorb metals from industrial and domestic effluent. Ten (10) of the commonest vegetables in Kenyan markets grown along these rivers and the soils in their rhizosphere from 25 sites were analyzed for Pb, Cu, Zn, Cd and Cr. Soils were air-dried then leached using 0.05 M EDTA, filtered and analysed in AAS. Vegetables were oven-dried, ground, ashed then analysed in AAS. In both soil and vegetables, the metal concentration was generally in the order Zn > Cu > Pb > Cd >Cr. In soil the concentrations were Pb 0.57 - 20 mg/kg, Cu 3.59 - 75.37 mg/kg, Zn 14.62 - 198.3 mg/kg, Cr 0.03 - 1.4 mg/kg and Cd 0 - 2.6 mg/kg. In vegetables the values were Pb 0 - 2.4 mg/kg, Cu 0.52 - 21.34 mg/kg, Zn 20.13 - 89.85 mg/kg, Cd 0 - 3.02 mg/kg and Cr 0 - 1.24 pp. There were significant differences within vegetables at each site (P<0.05). In most sites, there was a positive correlation of soil metal content with that in vegetables. The metal concentrations in soil were within permissible levels allowable by WHO/FAO except for a few instances in Cd. In vegetables all metals except Cu were in a few sites higher that the recommended limits. Government clean-up activities and monitoring of waste disposal is recommended for potential agricultural land.Key words: African Indigenous vegetables, heavy metals, pollution, urban and peri - urban agriculture, Nairobi

Evaluation of mycotoxin content in soybean (Glycine max l.) grown in Rwanda

Soybean is a critical food and nutritional security crop in Rwanda. Promoted by the Rwandan National Agricultural Research System for both adults and as an infant weaning food, soybean is grown by approximately 40% of households. Soybean may be susceptible to the growth of mycotoxin-producing moulds; however, data has been contradictory. Mycotoxin contamination is a food and feed safety issue for grains and other field crops. This study aimed to determine the extent of mycotoxin contamination in soybean, and to assess people’s awareness on mycotoxins. A farm-level survey was conducted in 2015 within three agro-ecological zones of Rwanda suitable for soybean production. Soybean samples were collected from farmers (n=300) who also completed questionnaires about pre-and post-harvest farm practices, and aflatoxin awareness. The concentration of total aflatoxin in individual soybean samples was tested by enzymelinked immunosorbent assay (ELISA) using a commercially-available kit. Other mycotoxins were analyzed using liquid chromatography-mass spectrometry (LCMS/ MS) on 10 selected sub samples. Only 7.3% of the respondents were aware of aflatoxin contamination in foods, but farmers observed good postharvest practices including harvesting the crop when the pods were dry. Using enzyme-linked immunosorbent assay (ELISA), only one sample had a concentration (11 μg/kg) above the most stringent EU maximum permitted limit of 4 μg/kg. Multi-mycotoxins liquid chromatography-mass spectrometry (LC-MS/MS) results confirmed that soybeans had low or undetectable contamination; only one sample contained 13μg/kg of sterigmatocystine. The soybean samples from Rwanda obtained acceptably low mycotoxin levels. Taken together with other studies that showed that soybean is less contaminated by mycotoxins, these results demonstrate that soybean can be promoted as a nutritious and safe food. However, there is a general need for educating farmers on mycotoxin contamination in food and feed to ensure better standards are adhered to safeguard the health of the consumers regarding these fungal secondary metabolites.Key words: soybean, safety, mould, aflatoxin, mycotoxins, sterigmatocystine, ELISA, LC-MS/MS, Rwand

The Long Life of Birds: The Rat-Pigeon Comparison Revisited

The most studied comparison of aging and maximum lifespan potential (MLSP) among endotherms involves the 7-fold longevity difference between rats (MLSP 5y) and pigeons (MLSP 35y). A widely accepted theory explaining MLSP differences between species is the oxidative stress theory, which purports that reactive oxygen species (ROS) produced during mitochondrial respiration damage bio-molecules and eventually lead to the breakdown of regulatory systems and consequent death. Previous rat-pigeon studies compared only aspects of the oxidative stress theory and most concluded that the lower mitochondrial superoxide production of pigeons compared to rats was responsible for their much greater longevity. This conclusion is based mainly on data from one tissue (the heart) using one mitochondrial substrate (succinate). Studies on heart mitochondria using pyruvate as a mitochondrial substrate gave contradictory results. We believe the conclusion that birds produce less mitochondrial superoxide than mammals is unwarranted

The Biochemical and Cellular Basis for Nutraceutical Strategies to Attenuate Neurodegeneration in Parkinson’s Disease

Future therapeutic intervention that could effectively decelerate the rate of degeneration within the substantia nigra pars compacta (SNc) could add years of mobility and reduce morbidity associated with Parkinson’s disease (PD). Neurodegenerative decline associated with PD is distinguished by extensive damage to SNc dopaminergic (DAergic) neurons and decay of the striatal tract. While genetic mutations or environmental toxins can precipitate pathology, progressive degenerative succession involves a gradual decline in DA neurotransmission/synaptic uptake, impaired oxidative glucose consumption, a rise in striatal lactate and chronic inflammation. Nutraceuticals play a fundamental role in energy metabolism and signaling transduction pathways that control neurotransmission and inflammation. However, the use of nutritional supplements to slow the progression of PD has met with considerable challenge and has thus far proven unsuccessful. This review re-examines precipitating factors and insults involved in PD and how nutraceuticals can affect each of these biological targets. Discussed are disease dynamics (Sections 1 and 2) and natural substances, vitamins and minerals that could impact disease processes (Section 3). Topics include nutritional influences on α-synuclein aggregation, ubiquitin proteasome function, mTOR signaling/lysosomal-autophagy, energy failure, faulty catecholamine trafficking, DA oxidation, synthesis of toxic DA-quinones, o-semiquinones, benzothiazolines, hyperhomocyseinemia, methylation, inflammation and irreversible oxidation of neuromelanin. In summary, it is clear that future research will be required to consider the multi-faceted nature of this disease and re-examine how and why the use of nutritional multi-vitamin-mineral and plant-based combinations could be used to slow the progression of PD, if possible

The Functional Morphology and Adaptations of the Epididymis in a Testicndid Mammal, The Rufous Sengi (Elephantulus rufescens).

Sengis are testicondid African mammals that constitute Order Macroscelidae. The epididymal morphology in the rufous sengis (Elephantulus rufescens) was studied with focus on features and adaptations that make it suitable for sperm maturation and storage in this testicondid mammal. The three topographic regions were distinct with the caput and cauda epididymis placed far apart, connected by a slender corpus. The caput occurred as a longitudinal mass on the dorsolateral border of the testis while the Cauda, pear-shaped mass, was laterally placed between the rectum and the pelvic urethra. The epididymal epithelium comprised principal and basal cells; the former exhibiting granules and apical blebbing in the caput. The lumen of the cauda was densely packed with spermatozoa that are occasionally wrapped by amorphous dark masses, and its principal cells had numerous vacuoles. This study demonstrates that beside merocrine secretion, principal cells of sengi’s caput also exhibit apocrine secretion as shown by apical blebs. The blebs are shed off plausibly as a means of delivering epididymosomes to the lumen, which in turn transfer epididymis-secreted proteins to the spermatozoa. Additionally, the study has shown that the cauda epididymis descends to a site probably cooler than the core body temperature for optimal sperm storage, with the vacuoles indicating its involvement in fluid re-absorption and phagocytosis