Food security and safety concerns in animal production and public health issues in Africa: A perspective of COVID-19 pandemic era

The impact of COVID-19 on food security can best be understood from the downturn on agricultural and other related economic activities which were almost brought to a total halt during the pandemic. The restriction of movement/lockdown policy instituted by various governments heavily affected local and national food production as farmers could not go to their farmlands. More so, there was price gouging on raw food items as local farmers were reducing cultivation and harvest because of their safety. The lockdown also affected the transportation of food products from farms and local companies to the market and across inter-state/province borders. Additionally, many human infections traceable to disease outbreak from animal origin suggest a great risk of exposure to infectious agents by live animal farmers. In combating this menace, local food production needs to be encouraged more, while measures should be put in place to facilitate farmer's participation in government regulations on enforcing biosecurity, health standards, disease monitoring, and surveillance practices.

Methicillin-resistant Staphylococcus aureus (MRSA) isolated from raw milk and nasal swabs of small ruminants in Abeokuta, Nigeria

Methicillin-resistant Staphylococcus aureus (MRSA), an important widespread cause of severe infection in both humans and animals, is a significant pathogen of public health concern. This study examined the presence of MRSA in 400 samples comprising 200 raw milks (145 from goat and 55 from sheep) and 200 nasal swabs (145 from goats and 55 from sheep) collected from ten different locations in Abeokuta, Nigeria. Samples were examined using standard bacteriological methods for the isolation and identification of Staphylococcus aureus and culture on oxacillin (6 μg/ml) and cefoxitin (2 μg/ml) selective media for the detection of MRSA. Suspected MRSA isolates were confirmed by latex agglutination test for the detection of penicillin-binding protein 2a (PBP2a). Antibiotic susceptibility testing was determined by Kirby Bauer disc diffusion method. Staphylococcus aureus was detected in 72 (18%) of 400 samples of which 52 (13%) were confirmed as MRSA. Methicillin-resistant S. aureus was detected in raw milk (37 of 200; 18.5%) and nasal swab (15 of 200; 7.5%). There was no significance difference (p > 0.05) in the prevalence of MRSA in sheep (37.7%) and goat (23.4%). The MRSA isolates showed resistance to ampicillin (100%), cloxacillin (100%), sulphamethoxazole-trimethoprim (100%), amoxicillin-clavulanate (84.6%), ceftriaxone (75%), cefuroxime (69.2%), erythromycin (65.4%), streptomycin (38.5%), ciprofloxacin (23.1%), pefloxacin (21.2%) and gentamicin (17.3%). The presence of multidrug-resistant MRSA in small ruminants reared in Abeokuta metropolis may be due to regular use of antibiotics and unhygienic practices by farmers. This in turn constitutes a potential public health risk to the owners, consumers of small ruminant products and the general populace.

Ultrastructural Studies of Acrosomal Formation in the Testis of Male Greater Cane Rat (Thryonomys swinderianus)

Purpose:

In furthering the understanding of the process of spermatogenesis in the greater cane rat, this study describes the ultrastructural spermiogenic transformation and acrosomal formation in the testes of this hystricomorphic rodent that is currently undergoing domestication in parts of West Africa.

Materials and Methods:

Testicular samples were obtained from ten sexually mature cane rats that were perfused-fixed using Karnovsky's fixative (phosphate buffered 2% paraformaldehyde – 2.5% glutaraldehyde fixative at pH 7.4). The samples were processed for ultrastructural analysis and examined under the transmission electron microscope.

Results:

The testes of the cane rat showed uniqueness in its cellular associations and the ultrastructure of the spermatogenic cells especially in the formation of the acrosome. The spermatid differentiation and acrosomal formation occurred in 12 steps with the first three steps being the Golgi phase and the next three steps making up the cap phase. While the three steps that follow constitute the acrosomal phase, the last 3 steps make up the maturation phase. At the cap and acrosomal phases, the entire acrosomal system comprising the vesicle and granule covers the head of the spermatids with no clear indentation of the nuclear surface by the formed acrosome. Furthermore, elongated spermatids at the maturation phase contained abundance of nuclear vacuoles.

Conclusion:

This work has not only provided information that will further the understanding of spermatogenesis but also aid the understanding of acrosomal reaction in the reproduction of the greater cane rat.

Immunolocalization And Distribution Pattern of Estrogen (ERα and ERβ) and Progesterone (PR) Receptors along the Excurrent Duct of Male Greater Cane Rat (Thryonomys swinderianus)

The excurrent duct, which plays vital roles in the reproductive biology of all male mammals, shows some structural variations among different species. Some hormones such as testosterone, estrogen and progesterone, through their different receptors, have been known to be involved in the normal functioning of the excurrent duct. Here we evaluated the presence, localization and patterns of distribution of three hormone receptors, estrogen alpha (ERα), estrogen beta (ERβ) receptors and progesterone receptors (PR) along the excurrent duct of sexually matured male greater cane rats. Immunohistochemistry revealed presence of ERα in epididymal stroma but not epithelium, selective ERβ staining in narrow & apical cells as well as unique presence of PR in caudal epididymis, which to the best of our knowledge, is the first report on the cellular localization of progesterone receptor in the cauda epididymis. The result suggests the possible involvement of not only estrogen but also progesterone in the modulation of epididymal function in greater cane rat.

Anatomical and immunohistochemical characteristics of the prostate gland in the greater cane rat (Thryonomys swinderianus)

This study examined the morphology and immunohistochemical features of the prostate gland in 15 captive-reared male greater cane rat of known reproductive and medical history. Samples of the glands were taken after gross examination and routinely prepared for both histological and ultrastructural analysis. Immunohistochemistry was also carried out on paraffin-embedded sections of the glands using rabbit polyclonal antibodies against oestrogen receptors (ERα and ERβ) and mouse monoclonal antibody for the progesterone receptor (PR). The prostate, which constitutes 0.04% of the body weight, was a paired, lobulated, brownish gland having three left and four right lobes that partly cover the pelvic urethra. Based on the amount and arrangement of the secretory epithelial folding and relative to their distances to the urethra, two histological zones, the central and peripheral, were identified. However, the epithelium of both zones was lined by predominantly simple cuboidal cells with occasional basal cells. The main ultrastructural features of these cuboidal cells were the presence of several nuclear pores on the nucleus, moderately well-developed, short microvilli and bleb-like apical projections, as well as inter-cellular lacunae seen between these cells and the basal cells. The cuboidal epithelial cells also showed positive nuclear staining for ERα and ERβ but not for PR. It is however interesting that the ERα-positive staining was more at the epithelial cells, which is uncommon. These findings highlight the peculiarities in the structure and ultrastructure as well as the unique expression of the oestrogen receptors in the prostate gland of the greater cane rat.

The structure of the penis with the associated baculum in the male greater cane rat (Thryonomys swinderianus)

In this study, the structures of penises of eight sexually mature male greater cane rats were examined at both macroscopic and histological levels. Each animal was sacrificed after anaesthesia with ether and then dissected open with the penis exposed from its root. The penises were first grossly examined, measured, and then prepared for histological examination. From this study it was observed that the body size has no allometry with penile size, but the testicular weight correlated with Os penis length in the greater cane rat. Grossly, the penis which was whitish in colour, with a mean length of 5.46 ± 0.36 cm, has no obvious collum penis but a flexura that turns it caudo-ventral and separates the corpus and glans penis. There was the presence of cornified papillae covering parts of the corpus and glans penis as well as a blind sac sacculus urethralis under the urethra on the glans penis. Histologically, the corpora cavernosa penis were completely separated by a connective tissue septum which sent the trabeculae network into the cavernous tissues and replaced the caverns as it moves from corpus to glans penis. The Os penis formed through endochondral ossification after 42 months of age in this animal. Therefore, from a histological standpoint, the cane rat penis belongs to the intermediate type. In conclusion, these findings provide vital information on the penile anatomy of the greater cane rat, which will serve as a basis for comparing penile morphology among the suborder hystricomorpha and expand knowledge of the reproductive biology in this animal.

The morphology and morphometry of the epididymis in the greater cane rat (Thryonomys swinderianus Temmincks)

The structure and morphometry of the epididymis in the greater cane rat were studied in this work. In assessing the morphology and characterising the morphometric values, a total of 15 adult male greater cane rats, bred and raised in captivity, were used. All the animals had brownish perineal staining, which was taken as index of sexual maturity in male cane rats, and they were maintained on elephant grass stems with water given ad libitum. From this work, the epididymis of the greater cane rat was observed to have a mean weight of 0.0365 ± 0.091 g, forming about 0.016% of the total body weight and an average volume of 0.36 ± 0.08 mL. There was a positive correlation between the epididymal weights, testicular weight, and the body weight in this animal. However, the gross divisions of the epididymis into head, body, and tail were not conspicuous in the cane rat; instead it had two divisions - the cranial and the caudal divisions. In addition, based on the histological and histomorphometric analyses, five zones were observed in the epididymal epithelium of this animal. This preliminary information on the epididymis will serve as a basis for further research on the epididymis of the greater cane rat and will contribute to the knowledge of the its reproductive biology, which will subsequently aid in the captive rearing and domestication of this animal.

Hexamethonium produces both twitch and tetanic depression without fade in common African toad (Bufo regularis)

The study was designed to investigate the nature of the cholinoceptors at the sciatic nerve-gastrocnemius muscle junction of the common African toad (Bufo regularis). Using myographic technique, the twitch properties of the sciatic-gastrocnemius muscle preparation of the common African toad was studied. Both the twitch height and peak tetanic height were measured as a percentage of control. Hexamethonium at a concentration of 0.1 mM significantly [P<0.05] reduced the mean twitch height from 2.62 cm to 1.0 cm and mean peak tetanic height from 5.38 cm to 4.32 cm. Hexamethonium, however does not produce tetanic fade at the same concentration. We hypothesized that the cholinoceptors of the neuromuscular junction of the common African toad (Bufo regularis) resemble the developing synapse of African clawed toad (Xenopus laevis) and may contain muscarinic M1 autoreceptors at the pre juntional membrane.

Job satisfaction among primary health care workers in three selected local government areas in southwest Nigeria

BACKGROUND

The primary health care system in Nigeria has been impaired by lack of dedicated workers who are willing to work in the rural areas. This study was carried out to examine factors that enhance job satisfaction among health workers in the primary health care system in Nigeria.

METHOD

The study is a cross-sectional descriptive study conducted in May 2002. The respondents were selected from three local government areas in southwest Nigeria by multistage sampling technique. A standardized structured pre-coded close-ended self-administered questionnaire to collect relevant information on their socio-demographic characteristics and extent of job satisfaction of respondents.

RESULT

A total of 125 health workers were interviewed in all. The mean score on job satisfaction was 26.15 out of the total possible score of 49. There was no statistically significant relationship in job satisfaction among the various cadres of health workers considered (p = 0.824). A larger proportion (66.4%) of the health workers were involved with the community based preventive services when compared with the health centre based curative care 33.4% (p < 0.05), there is however no significant difference in satisfaction between this two groups of personnel (p = 0.133). Age and marital status were found to be statistically significant in relation to job satisfaction (p = 0.000 and 0.034 respectively).

CONCLUSION

The study shows no significant difference in job satisfaction among the various cadres of health workers in southwest Nigeria. However age and marital status were found to be significant factors influencing job satisfaction among the primary health care workers in Nigeria.

Two residues that may ligate Ca2+ in transmembrane domain six of the plasma membrane Ca(2+)-ATPase

In order to identify Ca2+ ligands in the putative transmembrane domain 6 of the plasma membrane Ca2+ pump, amino acids Asn879, Met882, Asp883, and Ser887 were singly altered. Asn879, Met882, and Asp883 were chosen because the corresponding amino acids have been proposed as Ca2+ ligands in the sarcoplasmic reticulum Ca2+ pump (Clarke, D. M., Loo, T. W., and MacLennan, D. H. (1990) J. Biol. Chem. 265, 6262-6267). For the alterations, a fully active truncated version of the pump was used, because the interaction of Ca2+ with the pump could be studied without interference from calmodulin binding. The mutants at Asn and Asp did not carry out ATP-supported Ca2+ uptake and formed no acylphosphate from [gamma-32P]ATP, suggesting that, like the corresponding amino acids in the sarcoplasmic reticulum Ca2+ pump, these two are Ca2+ ligands. However, all the mutants at the position of Met882 showed some activity. Indeed, the Met882--> Ile mutant was fully active at a saturating Ca2+ concentration and only the K1/2 for Ca2+ activation was shifted slightly upward. Converting the Met to Thr (which is the corresponding residue in the sarcoplasmic reticulum Ca2+ pump) reduced the activity to 20% of the wild type, further emphasizing the differences between the two Ca2+ pumps. The mutant Ser887--> Ala was expressed in greater amounts than, and had a specific activity about 50% higher than, the wild type, indicating that this serine also could not be a Ca2+ ligand and could not replace the missing Thr at position Met882.

The anticalmodulin effect of aflatoxin B1 on purified erythrocyte Ca(2+)-ATPase

The genotoxic carcinogen aflatoxin B1 (AFB1) inhibited the calmodulin-stimulated membrane-bound (Ca2+Mg2+)-ATPase. Using the purified enzyme, 12 nmoles per ml of AFB1 caused maximum inhibition of 28% and 50%, of the acidic phospholipid-stimulated and calmodulin-activated Ca(2+)-ATPase activity respectively. Treatment of red cell ghosts with increasing concentrations of Triton X-100, a non-ionic detergent caused a progressive loss of both the basal and calmodulin-stimulated Ca(2+)-ATPase activity. The activity of the phospholipid-free, detergent-solubilized enzyme was almost fully restored by phosphatidyl serine (PS) and its sensitivity to calmodulin was restored in the presence of phosphatidyl choline (PC). Analysis of the results obtained using varying concentrations of ATP shows that AFB1 did not affect the Km and Vmax of the unstimulated enzyme whereas these parameters were reduced by about 75% and 50%, respectively, in the presence of calmodulin. Using the product of limited proteolysis by trypsin i.e. the 90 kDa fragment which still retains its calmodulin binding-domain and the 76 kDa fragment which has lost this domain, kinetic studies on the enzyme activity revealed that AFB1 inhibited the calmodulin-activated 90 kDa fragment by about 50% while the 76 kDa was not affected at all by the toxin and calmodulin. The toxin had no significant affect on the basal activity of the 90 kDa limited proteolysis fragment of the enzyme. These observations suggest that AFB1 inhibits the activated Ca(2+)-ATPase by binding to an important site in the calmodulin-binding domain of the enzyme. It seems likely that the toxin binds to tryptophan in the calmodulin-binding domain, thus causing a reduction in the rate at which this domain can interact with Ca(2+)-calmodulin or acidic phospholipids. The implication of these observations is that Ca(2+)-extrusion and other calmodulin-activated enzymes and processes may be slowed down during prolonged exposure to AFB1 because of its anticalmodulin effect.

Comparative action of calpain on erythrocyte Ca2(+)-pumping ATPase in sickle cell anaemia, essential hypertension and kwashiorkor

Calpain, a calcium-dependent, neutral cysteine-protease was purified from the erythrocyte cytosol of subjects having essential hypertension (HTN), sickle cell anaemia, (SCA), or kwashiorkor (KWA). Identical electrophoretic mobility on SDS-polyacrylamide gradient gel, sensitivity to micromolar amounts of Ca2+, absolute requirement for a reducing environment and a high susceptibility to inhibition by leupeptin and thiol-group modifying reagents confirm that calpain preparations from these erythrocytes are equivalent to calpain I. Whereas the extent of calpain activation of erythrocyte membrane Ca2(+)-pumping ATPase of normal subjects was almost equal to that due to calmodulin, calpain activation of the HTN and SCA pump was greater than activation by calmodulin. Like in normal membranes, exogenous calmodulin protected the Ca2(+)-pumping ATPase of these erythrocytes against calpainization; the degree of protection by calmodulin is least in SCA and HTN. Electrophoretic separation of erythrocyte membranes and the purified Ca2(+)-pumping ATPase of HTN, SCA and KWA subjects does not indicate the presence of fragments resulting from the proteolytic action of calpain.