Establishment of callus derived from Jatropha curcas L. petiole explants and phytochemical screening

Abstract Aims: The focus of this study was to assess the production of secondary metabolites of callus derived from Jatropha curcas L. petiole explants. Results: Excellent growth of callus was obtained. Callus was soft, friable, lush green in color and grew fast from 8 to 30 days of culture then stabilized at low growth rate. The results obtained by phyto-chemical tests revealed the presence of saponins, tannins, alkaloids, steroids and flavonoids. The tannin contents in vitro proliferated callus, leaves, stem barks, root barks, roots and latex of J. curcas were found to be 161, 173, 220, 214, 43 and 245 μg tannic acid equivalent/g of dry weight respectively. Conclusion: The results of this study have revealed that in vitro induced callus from J. curcas petiole explants was able to produce secondary metabolites. The pharmacological activity of J.curcas reported by various researchers can be attributed to the presence of these phytochemicals

A monovalent chimpanzee adenovirus Ebola vaccine boosted with MVA

BACKGROUND The West African outbreak of Ebola virus disease that peaked in 2014 has caused more than 11,000 deaths. The development of an effective Ebola vaccine is a priority for control of a future outbreak. METHODS In this phase 1 study, we administered a single dose of the chimpanzee adenovirus 3 (ChAd3) vaccine encoding the surface glycoprotein of Zaire ebolavirus (ZEBOV) to 60 healthy adult volunteers in Oxford, United Kingdom. The vaccine was administered in three dose levels — 1×1010 viral particles, 2.5×1010 viral particles, and 5×1010 viral particles — with 20 participants in each group. We then assessed the effect of adding a booster dose of a modified vaccinia Ankara (MVA) strain, encoding the same Ebola virus glyco- protein, in 30 of the 60 participants and evaluated a reduced prime–boost interval in another 16 participants. We also compared antibody responses to inactivated whole Ebola virus virions and neutralizing antibody activity with those observed in phase 1 studies of a recombinant vesicular stomatitis virus–based vaccine expressing a ZEBOV glycoprotein (rVSV-ZEBOV) to determine relative potency and assess durability. RESULTS No safety concerns were identified at any of the dose levels studied. Four weeks after immunization with the ChAd3 vaccine, ZEBOV-specific antibody responses were similar to those induced by rVSV-ZEBOV vaccination, with a geometric mean titer of 752 and 921, respectively. ZEBOV neutralization activity was also similar with the two vaccines (geo- metric mean titer, 14.9 and 22.2, respectively). Boosting with the MVA vector increased virus-specific antibodies by a factor of 12 (geometric mean titer, 9007) and increased glycoprotein-specific CD8+ T cells by a factor of 5. Significant increases in neutralizing antibodies were seen after boosting in all 30 participants (geometric mean titer, 139; P<0.001). Virus-specific antibody responses in participants primed with ChAd3 remained positive 6 months after vaccination (geometric mean titer, 758) but were significantly higher in those who had received the MVA booster (geometric mean titer, 1750; P<0.001). CONCLUSIONS The ChAd3 vaccine boosted with MVA elicited B-cell and T-cell immune responses to ZEBOV that were superior to those induced by the ChAd3 vaccine alone. (Funded by the Wellcome Trust and others; ClinicalTrials.gov number, NCT02240875.

Ivermectin treatment of Loa loa hyper-microfilaraemic baboons (Papio anubis): Assessment of microfilarial loads, haematological and biochemical parameters and histopathological changes following treatment.

Individuals with high intensity of Loa loa are at risk of developing serious adverse events (SAEs) post treatment with ivermectin. These SAEs have remained unclear and a programmatic impediment to the advancement of community directed treatment with ivermectin. The pathogenesis of these SAEs following ivermectin has never been investigated experimentally. The Loa/baboon (Papio anubis) model can be used to investigate the pathogenesis of Loa-associated encephalopathy following ivermectin treatment in humans. 12 baboons with microfilarial loads > 8,000mf/mL of blood were randomised into four groups: Group 1 (control group receiving no drug), Group 2 receiving ivermectin (IVM) alone, Group 3 receiving ivermectin plus aspirin (IVM + ASA), and Group 4 receiving ivermectin plus prednisone (IVM + PSE). Blood samples collected before treatment and at Day 5, 7 or 10 post treatment, were analysed for parasitological, hematological and biochemical parameters using standard techniques. Clinical monitoring of animals for side effects took place every 6 hours post treatment until autopsy. At autopsy free fluids and a large number of standard organs were collected, examined and tissues fixed in 10% buffered formalin and processed for standard haematoxylin-eosin staining and specific immunocytochemical staining. Mf counts dropped significantly (p0.05). All animals became withdrawn 48 hours after IVM administration. All treated animals recorded clinical manifestations including rashes, itching, diarrhoea, conjunctival haemorrhages, lymph node enlargement, pinkish ears, swollen face and restlessness; one animal died 5 hours after IVM administration. Macroscopic changes in post-mortem tissues observed comprised haemorrhages in the brain, lungs, heart, which seen in all groups given ivermectin but not in the untreated animals. Microscopically, the major cellular changes seen, which were present in all the ivermectin treated animals included microfilariae in varying degrees of degeneration in small vessels. These were frequently associated with fibrin deposition, endothelial changes including damage to the integrity of the blood vessel and the presence of extravascular erythrocytes (haemorrhages). There was an increased presence of eosinophils and other chronic inflammatory types in certain tissues and organs, often in large numbers and associated with microfilarial destruction. Highly vascularized organs like the brain, heart, lungs and kidneys were observed to have more microfilariae in tissue sections. The number of mf seen in the brain and kidneys of animals administered IVM alone tripled that of control animals. Co-administration of IVM + PSE caused a greater increase in mf in the brain and kidneys while the reverse was noticed with the co-administration of IVM + ASA. The treatment of Loa hyper-microfilaraemic individuals with ivermectin produces a clinical spectrum that parallels that seen in Loa hyper-microfilaraemic humans treated with ivermectin. The utilization of this experimental model can contribute to the improved management of the adverse responses in humans

A randomised controlled trial comparing haemodynamic stability in elderly patients undergoing spinal anaesthesia at L5,S1 versus spinal anaesthesia at L3,4 at The Aga Khan University Hospital, Nairobi

Background: Spinal anaesthesia is a routinely used anaesthetic technique for elderly patients undergoing operations involving the lower limbs, lower abdomen, pelvis and the perineum. Spinal anaesthesia has several advantages over general anaesthesia and these include stable haemodynamic variables, less blood loss, less post operative pain, faster recovery time and less post operative confusion. However, despite these advantages, the sympathetic blockade induced by spinal anaesthesia can result in hypotension, bradycardia, dysrhythmias and cardiac arrests. Conventionally, spinal anaesthesia is performed at the level of L3,4 interspace; with a reported incidence of hypotension in the elderly ranging between 65% and 69%. A possible strategy for reducing spinal induced hypotension would be to minimize the peak block height to as low as possible for the planned procedure. The purpose of this study was to investigate the decrease in mean arterial pressures and change heart rates from baseline values (haemodynamic stability) of elderly patients undergoing spinal anaesthesia performed at the level of L5, S1 compared to the conventional level at the L3, 4 interspace. Objective: To determine the difference in haemodynamic stability between elderly patients undergoing spinal anaesthesia at L5, S1 interspace compared to elderly patients undergoing spinal anaesthesia at L3, 4. Study design: A randomized single blinded controlled trial Methods: Thirty two elderly patients scheduled for lower limb or pelvic surgery under spinal anaesthesia were randomized into 2 groups (control group and intervention group) using a computer generated table of numbers. Control group; received 2.5 mls 0.5% hyperbaric bupivacaine injected intrathecally at the L3, 4 interspace Intervention group; 2.5mls 0.5% hyperbaric bupivacaine injected intrathecally at the L5, S1 interspace Results: The two groups had similar baseline characteristics in age, sex, body mass index and use of anti-hypertensive medications. There was 68.75% proportion of hypotension in the control group and 75% in the intervention group. The difference was not found to be statistically significant (p= 0.694). During the study period, there were 106 episodes of hypotension, out of which, 65 were in the control group and 41 in the intervention group (p=0.004). This difference was statistically significant.Linear regression analysis of the decrease in mean arterial pressures (MAP) showed a higher decrease in MAP in the control group (p 0.018). There were more crystalloids used in the control group (1006mls ± 374) than in the intervention group (606mls ±211) with a p\u3c 0.0001. There was no difference in the amounts of vasopressors used between the two groups (p=0.288).There was no difference in the change in heart rates,conversion to general anaesthesia, use of supplementary intravenous fentanyl and the peak maximum block level achieved. The time to peak maximum level was 9.06min and 13.07min in the control group and intervention groups, respectively (p\u3c0.0001). Conclusion: Among this population, there was no difference in the proportion of those with hypotension between the elderly patients who received their spinal anaesthesia at L3,4 and those who received spinal anaesthesia at L5,S1. There were significantly less episodes of hypotension in the intervention group. It took a longer time to achieve a maximum peak sensory block in the intervention group. Performing spinal anaesthesia at the level of L5,S1 was found to provide an adequate sensory block for a wide range of pelvic, perineal and lower limb surgeries. The study was registered under Pan African Clinical Trials Registration number PATCR 20110900031131

Dynamics of SARS-CoV-2 exposure in Malawian blood donors: a retrospective seroprevalence analysis between January 2020 and February 2021

Background As at end of July 2021, the COVID-19 pandemic has been less severe in sub-Saharan Africa than elsewhere. In Malawi, there have been two subsequent epidemic waves. We therefore aimed to describe the dynamics of SARS-CoV-2 exposure in Malawi. Methods We measured the seroprevalence of anti-SARS-CoV-2 antibodies among randomly selected blood donor sera in Malawi from January 2020 to February 2021. In a subset, we also assesed in vitro neutralisation against the original variant (D614G WT) and the Beta variant. Findings A total of 3586 samples were selected from the blood donor database, of which 2685 (74.9%) were male and 3132 (87.3%) were aged 20-49 years. Of the total, 469 (13.1%) were seropositive. Seropositivity was highest in October 2020 (15.7%) and February 2021 (49.7%) reflecting the two epidemic waves. Unlike the first wave, both urban and rural areas had high seropositivity by February 2021, Balaka (rural, 37.5%), Blantyre (urban, 54.8%), Lilongwe (urban, 54.5%) and Mzuzu (urban, 57.5%). First wave sera showed potent in vitro neutralisation activity against the original variant (78%[7/9]) but not the Beta variant (22% [2/9]). Second wave sera potently neutralised the Beta variant (73% [8/11]). Interpretation The findings confirm extensive SARS-CoV-2 exposure in Malawi over two epidemic waves with likely poor cross-protection to reinfection from the first on the second wave. Since prior exposure augments COVID-19 vaccine immunity, prioritising administration of the first dose in high SARS-CoV-2 exposure settings could maximise the benefit of the limited available vaccines in Malawi and the region. Research in context Evidence before this study We searched PubMed on August 16, 2021, with no language restrictions, for titles and abstracts published between Jan 1, 2020, and August 16, 2021, using the search terms: “SARS-CoV-2 seroprevalence in Africa”[Title/Abstract]) OR “SARS-CoV-2 seroprevalence in blood donors” [Title/Abstract] OR “SARS-CoV-2 seroprevalence in Malawi”, and found 15 records. There are limited SARS-CoV-2 seroprevalence studies in sub Saharan Africa, however the few that are available report high seroprevalence than can be deduced from the respective national reported COVID-19 cases and deaths. Only two published SARS-CoV-2 serosurveys were done on blood donors, from Kenya and Madagascar. Blood donor serosurveys have been recommended by the WHO as an important tool for assessing the spread of SARS-CoV-2 and estimating the burden of COVID-19 pandemic. Added value of this study Unlike previous SARS-CoV-2 blood donor serosurveys in African populations that were conducted for a maximum period of 9 months, our study covers a full year from January 2020 to February 2021, capturing potential introduction of SARS-CoV-2 into Malawi as well as the two epidemic waves. This study provides evidence against the speculation that SARS-CoV-2 had been circulating more widely in sub-Saharan Africa before the first detected cases. It also provides supporting evidence suggesting that the Beta variant was the likely driver of the second wave that resulted in high SARS-CoV-2 seropositivity in January to February 2021 in Malawi. Implications of all the available evidence Our results show extensive community transmission of SARS-CoV-2 in Malawi as reflected in the blood donors serosurvey, with almost half the sample population being seropositive for anti-SARS-CoV-2 antibodies by February 2021. This has implications for COVID-19 vaccination policy in sub-Saharan Africa (SSA), where there are limited available vaccine doses. Considering that prior exposure to SARS-CoV-2 augments COVID-19 vaccine immunity, strategies to maximise administration of the first vaccine dose, while waiting for more vaccines to become available, could maximise the benefits of the limited available vaccines in high SARS-CoV-2 exposure settings in SSA such as Malawi