Biomedical subjects

Ohene Adjei

Publications and source records attributed to Ohene Adjei.

6 recordsLinked to original sources

PubMed2003

Doxycycline as a novel strategy against bancroftian filariasis-depletion of Wolbachia endosymbionts from Wuchereria bancrofti and stop of microfilaria production.

Chemotherapy of onchocerciasis by doxycycline, which targets symbiotic Wolbachia endobacteria, has been shown to result in a long-term sterility of adult female worms and corresponding absence of microfilariae. It represents an additional chemotherapeutic approach. The aim of this study was to determine whether a similar regimen would also show efficacy against Wuchereria bancrofti. Ghanaian individuals ( n=93) with lymphatic filariasis and a minimum microfilaremia of 40 microfilariae/ml were included in a treatment study consisting of four arms: (1) doxycycline 200 mg/day for 6 weeks; (2) doxycycline as in (1), followed by a single dose of ivermectin after 4 months; (3) ivermectin only; or (4) no treatment during observation period of 1 year (ivermectin at the end of the study). Doxycycline treatment resulted in a 96% loss of Wolbachia, as determined by real time PCR from microfilariae. After 12 months, doxycycline had led to a 99% reduction of microfilaremia when given alone, and to a complete amicrofilaremia together with ivermectin. In contrast, after ivermectin treatment alone a significant presence of microfilariae remained (9% compared to pretreatment), as known from other studies. This study shows that doxycycline is also effective in depleting Wolbachia from W. bancrofti. It is likely that the mechanism of doxycycline is similar to that in other filarial species, i.e., a predominant blockade of embryogenesis, leading to a decline of microfilariae according to their half-life. This could render doxycycline treatment an additional tool for the treatment of microfilaria-associated diseases in bancroftian filariasis, such as tropical pulmonary eosinophilia and microfiluria.

Adolescent↗

PubMed2003

Animated documentation of the filaria dance sign (FDS) in bancroftian filariasis.

BACKGROUND: Ultrasonography is able to detect adult Wuchereria bancrofti worms in scrotal lymphatic vessels of infected men on account of the characteristic pattern of adult worm movements, known as the filarial dance sign. Furthermore, the technique is able to delineate associated pathology, such as hydrocoele and lymphoedema, which can be diagnosed in early stages. Ultrasonography is also useful in the assessment of macrofilaricidal effects of antifilarial medication.The purpose of this study was to evaluate the usefulness of scrotal ultrasonography, in combination with a new method of digital documentation, in men infected with Wuchereria bancrofti. METHODS: Ultrasonography of the scrotal areas was carried out in 33 male patients from an endemic area in Ghana using a hand-carried ultrasound system and a linear array transducer at 7.5 MHz. Wuchereria bancrofti infection was also assessed by quantification of night blood microfilaraemia and semi-quantitative detection of circulating filarial antigen. Ultrasound findings were documented by print outs and by Digital Video sequences directly exported from the ultrasound machine which were edited in Final Cut Pro 3ledR; and exported, using QuickTimecircledR; Pro, as MPEG-1 video. RESULTS: Worm nests, i.e. dilated lymphatic vessels with the characteristic movement patterns of worms, were found in all patients, and typical examples of larger as well as smaller nests are presented through MPEG-1 video in b- and m-modes as well as Colour Doppler and Pulse Wave Doppler images. CONCLUSION: In this study, the filarial dance sign is being made available on the Internet to readers through MPEG-1 video. This method allows for demonstration of movement patterns rather than static images. In addition, the pathologic ultrasonographic signs of filariasis can be rapidly relayed over great distances and may be helpful to other investigators or clinicians in the diagnosis of patients infected with Wuchereria bancrofti.

Journal Article↗

PubMed2003

Onchocerciasis.

Explore the source record for details and available documents.

Animals↗

PubMed2003

Doxycycline in the treatment of human onchocerciasis: Kinetics of Wolbachia endobacteria reduction and of inhibition of embryogenesis in female Onchocerca worms.

Recently, experts have warned that mass treatment with ivermectin alone may not interrupt the transmission of Onchocerca. Hence, additional drugs are needed, such as antibiotics acting on symbiotic endobacteria of the filariae, the causative agents of onchocerciasis. Based on animal experiments, human onchocerciasis was treated with doxycycline, and preliminary observations published in 2001 in The Lancet showed sterility in female worms by depletion and marked reduction in symbiotic Wolbachia endobacteria from the filariae. Here, a detailed kinetic analysis of the features of the worms, following administration or not of doxycycline to the patients is reported. Sixty-three onchocerciasis patients in Ghana were treated with 100 mg doxycycline daily for 6 weeks and 2 or 6 months later with ivermectin. Onchocercomas were extirpated 2, 6, 11 and 18 months after the onset of treatment and the filariae were examined by immunohistology and PCR. The analysis showed: (i) progressive depletion of Wolbachia from adult worms and microfilariae by doxycycline over a period of 6 months; (ii) inhibition of embryogenesis by doxycycline after 6 months with respect to all embryo stages followed by decline in microfilariae after 11 months; (iii) reduction in spermatozoa in the female genital tract by doxycycline, whereas spermiogenesis was only partly reduced after 11 and 18 months; (iv) no relevant macro- or microfilaricidal activity; (v) depletion/marked reduction in endobacteria and inhibition of embryogenesis were sustained until 18 months after doxycycline and 12 months after co-administration of ivermectin; (vi) no severe adverse side effects were seen. Due to its long-lasting inhibition of embryogenesis, doxycycline presents an additional strategy for the treatment of onchocerciasis and control of Onchocerca microfilariae transmission. Extension of the existing registration will not require much time or high cost. Treatment of individual patients can be considered immediately.

Animals↗

PubMed2002

Antigen-specific T regulatory-1 cells are associated with immunosuppression in a chronic helminth infection (onchocerciasis).

Different mechanisms underlie the phenomenon of peripheral tolerance. Recently, a new subset of CD4+ T cells, called T regulatory-1 (Tr1) cells, was described which show suppressor functions in vitro and in vivo and are characterized by a predominant production of IL-10 and/or TGF-beta. Tr1 cells have so far been generated experimentally in an IL-10-rich environment and hold promise for exploitation in the suppression of alloreactions and inflammatory or allergic dispositions. However, these cells have not been characterized in infectious diseases. Here we show that in the chronic helminth infection onchocerciasis (river blindness), where patients have relatively little sign of dermatitis despite the presence of millions of small worms in the skin, T cells can be obtained which bear characteristics of Tr1 cells, producing no IL-2 or IL-4 but substantial amounts of IL-10, variable amounts of IL-5, and some IFN-gamma. These cells display elevated amounts of CTLA-4 after stimulation and are able to inhibit other T cells in coculture, in contrast to Th1 and Th2 clones. This is the first time that this type of suppressor T cell has been cloned as naturally occurring during an infectious disease.

Abatacept↗

PubMed2002

Antibiotics for the treatment of onchocerciasis and other filarial infections.

More effective drugs are needed for the treatment of human filarial diseases and the elimination of these infections as a public health problem. The drugs must either kill or sterilize adult worms. The relevant filariae, Onchocerca volvulus, Wuchereria bancofti and Brugia species, harbor rickettsial endoboacteria of the genus Wolbachia as symbionts. Animal experiments have shown that the elimination of these endobacteria causes inhibition of embryogenesis, and with Onchocerca ochengi a macrofilaricidal effect. Trials with human onchocerciasis patients using doxycydine demonstrated a long-term sterilizing activity, opening up a new strategy for the control of filarial infections. Indications of antiwolbachial therapy against onchocerciasis are discussed.

Animals↗