Magnetotactic bacteria used to generate electricity based on Faraday's law of electromagnetic induction.

Magnetotactic bacteria (MTB) have the unique ability to produce magnetic particles surrounded by a biomembrane to form the magnetosome organelle. Therefore, MTB have novel physical and magnetic properties and have consequently been used in several biotechnological applications. The magnetic properties of these micro-organisms and their magnetosomes have, however, never been used for the generation of electricity as described in this letter. Comparisons were made between, firstly, the electricity generated from purified magnetosomes, MTB culture (bacterial cells with magnetosomes) and sterile, liquid growth medium (control). Secondly, the electricity generated by a dilution series of purified magnetosomes were compared. A statistically significant difference was found between the voltage measured from the purified magnetosomes (highest voltage), MTB culture (lower voltage) and liquid growth medium (lowest voltage). In the dilution series, the voltage measured increased as the magnetosome concentration increased, but only up to an optimum concentration (0·0376 mg ml-1 ). In this study, we have demonstrated that a significantly higher voltage than that of the control could be measured when MTB or purified magnetosomes were pumped through a solenoid by applying Faraday's law of electromagnetic induction. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides proof-of-concept of electromagnetic induction using magnetosomes or magnetotactic bacteria in an experimental setup based on the law of Faraday. The concept of using these bacteria or their biomineralized magnetic nanoparticles as a biological alternative in low voltage electricity generation has the potential to be further explored and developed.

Fusarium dimerum as a cause of human eye infections.

Fusarium dimerum, typically a soil fungus, was isolated from an adult male suffering from a corneal ulcer following an injury to the eye. This fungus has not been described to cause human infections in South Africa and has not been recorded from soil, plant or organic material in this country. The macro- and microscopic characteristics of the isolate were found to be indistinguishable from described strains. Its authenticity was confirmed by comparing it to other human isolates from the eye obtained in the USA, thus rendering this the first report of F. dimerum from an eye infection in a human in South Africa.

Demonstration of reinfection and reactivation in HIV-negative autopsied cases of secondary tuberculosis: multilesional genotyping of Mycobacterium tuberculosis utilizing IS 6110 and other repetitive element-based DNA fingerprinting.

SETTING: Secondary tuberculosis may follow reinfection or endogenous reactivation. The design of effective preventive and treatment protocols requires knowledge about the relative importance of these mechanisms in specific communities. Molecular typing of Mycobacterium tuberculosis has permitted linkage of cases and demonstration of patterns of inter- or intrapatient strain diversity correlating with reinfection and reactivation. OBJECTIVE: The use of DNA fingerprinting to examine intrapatient strain diversity in autopsied, HIV-negative individuals resident in a high incidence community. DESIGN: Autopsy (12 cases) and pneumonectomy (one case) permitted multilesional sampling for bacterial culture and comparative genotyping. Mycobacterium tuberculosis strains were typed using probes directed against IS 6110, the direct repeat sequence (DR) and MTB484(1). RESULTS: In two patients, the demonstration of pulmonary infection by two distinct strains suggested dual infection of these individuals. In one other case, the strain isolated from a Ghon-focus was identical to that obtained from all secondary cavitating lesions, which suggested reactivation of the primary infection. In the remaining cases, all isolates were identical, but primary lesions could not be identified with certainty or were culture negative. One of these cases showed evidence of strain evolution. CONCLUSIONS: Multilesional strain genotyping suggested both reinfection and reactivation in a series of HIV-negative autopsied patients with secondary tuberculosis. In most (11/13) cases, the same strain (or clonal variant) was present in all lesions, pulmonary and extrapulmonary.

Characterization of pentocin TV35b, a bacteriocin-like peptide isolated from Lactobacillus pentosus with a fungistatic effect on Candida albicans.

Lactobacillus pentosus TV35b, isolated from the posterior fornix secretions of the vagina of a prenatal patient, produced a bacteriocin-like peptide (pentocin TV35b), which is inhibitory to Clostridium sporogenes, Cl. tyrobutyricum, Lact. curvatus, Lact. fermentum, Lact. sake, Listeria innocua, Propionibacterium acidipropionici, Propionibacterium sp. and Candida albicans. The mechanism of activity of pentocin TV35b is bactericidal, as shown by a decrease in the viable cell numbers of Lact. sake from approximately 4 x 108 to less than 10 cfu ml - 1 over a period of 4 h. Pentocin TV35b added to the growth medium of C. albicans stimulated the formation of pseudohyphae during the first 36 h, followed by a slight repression in cell growth. Production of pentocin TV35b was at its maximum towards the end of the logarithmic growth phase of strain TV35b. The peptide was purified by ammonium sulphate precipitation, followed by SP-Sepharose cation exchange chromatography. The molecular size of pentocin TV35b was estimated to be between 2.35 and 3.4 kDa, according to tricine-SDS PAGE. However, results obtained by electrospray ionization mass spectroscopy indicated that the peptide is 3930.2 Da in size. Amino acid analysis performed by using the Pico-Tag(R) method and a Nova-Pak C18 HPLC column indicated that pentocin TV35b consists of 33 amino acids with a total mass of 3929.63 Da. Pentocin TV35b is inactivated when treated with papain and Proteinase K, but remains active after incubation at pH 1-10 for 2 h at 25 degrees C, and when heat-treated for 30 min at 100 degrees C.

Classification of heparinolytic bacteria into a new genus, Pedobacter, comprising four species: Pedobacter heparinus comb. nov., Pedobacter piscium comb. nov., Pedobacter africanus sp. nov. and Pedobacter saltans sp. nov. proposal of the family Sphingobacteriaceae fam. nov.

Sixteen heparinase-producing isolates, related to Sphingobacterium heparinum, were grouped into three major clusters by SDS-PAGE and DNA-rRNA hybridizations. Based on a polyphasic approach, it was shown that isolates of two of these clusters and S. heparinum species belong to a new genus for which the name Pedobacter is proposed. The genus consists of Pedobacter heparinus comb. nov. (formerly Sphingobacterium heparinum), which is the type species, Pedobacter piscium comb. nov. (formerly Sphingobacterium piscium), Pedobacter africanus sp. nov. and Pedobacter saltans sp. nov. and four as-yet-unnamed DNA hybridization groups. All the previously named taxa can be discriminated by phenotypic features, but have strong overall similarities with representatives of the genus Sphingobacterium and the misclassified species [Flexibacter] canadensis. All these organisms constitute a separate rRNA branch in rRNA superfamily V for which the family Sphingobacteriaceae fam. nov. is proposed.

Do vaginal lactobacilli prevent preterm labour?

OBJECTIVE: To determine the prevalence of Lactobacillus spp. in vaginal flora during pregnancy and to assess the protective effects of lactobacilli against preterm labour. DESIGN: Cross-sectional analysis of Lactobacillus spp. in the vaginal flora of the pregnant coloured population of the Western Cape. PARTICIPANTS: A total of 480 consecutive pregnant women, aged 13-48 years, seen at their first visit to the Tygerberg Hospital antenatal clinic. MAIN OUTCOME MEASURES: Preterm labour, i.e. before 34 and 37 weeks' gestation, premature rupture of membranes, intra-uterine growth retardation and perinatal deaths. RESULTS: A total of 163 patients had negative cultures and 317 positive cultures for lactobacilli, aerobes or both. Delivery before 37 weeks occurred in 18% and 20% of the two groups, respectively. Lactobacillus only was cultured from 116 patients and Lactobacillus and/or other aerobes from 201 patients. Preterm labour occurred in 20% of the first group and in 19% of the second group. The perinatal outcome in patients from whom lactobacilli only were cultivated did not differ from patients from whom other aerobes and lactobacilli or other aerobes only were cultured. CONCLUSION: In patients at high risk for preterm labour, the presence of lactobacilli in the vagina does not seem to play a protective role.

Current status of food-borne parasitic zoonoses in South Africa and Namibia.

Epidemiological data on food-borne parasitic zoonoses in countries of southern Africa are sporadic. In a study of toxoplasmosis in South Africa, there was an overall prevalence of 21% (2, 147/10,228). Prevalences vary between the different cultural groups and from one geographical region to another. The prevalence rate for the San (Bushmen) people of Namibia and Botswana was 9% (65/725) compared to the 30% (190/635) found in the Indian and Black communities of Kwazulu-Natal province, South Africa. These variations are probably linked to the dietary habits of the different cultural communities. Cysticercosis appears to be most prevalent in the Eastern Cape Province (former Transkei), where pigs roam freely and sanitation facilities are inadequate or non-existent. Segments of tapeworms often feature as an ingredient of concoctions prepared by traditional healers and are suspected sources of many of the cases of cysticercosis in South Africa. Trichinella nelsoni has been identified in wild game in South Africa: so far no cases of infection in humans have been recorded. Cases of Sarcocystis have been identified in some instances but infection is probably underdiagnosed in the country.

Analgesic and anti-inflammatory efficacy of tenoxicam and diclofenac sodium after third molar surgery.

Tenoxicam and diclofenac sodium were compared with each other for analgesic efficacy following removal of third molars under general anesthesia. Thirty-five healthy patients between the ages of 18 and 28 yr were randomly allocated to two groups to participate in this study. Patients in Group A (n = 17) received a single intravenous injection of tenoxicam 40 mg at induction of anesthesia, followed by a 20-mg tablet given in the evening of the day of the operation and thereafter, one 20-mg tablet daily from days 2 to 7. Group B (n = 18) received a single intramuscular injection of diclofenac sodium 75 mg at induction of anesthesia, followed by a 50-mg tablet 4 to 6 hr after the operation and again, between 2100 hr and 2200 hr the same day. Thereafter, a 50-mg tablet was taken 3 times daily for the next 6 days. Pain was measured hourly for the first 4 hr postoperatively, then at 21 hr, and thereafter in the morning and the evenings on days 2 to 7. The highest pain scores were obtained 1 hr postoperatively for both trial groups. At 1 and 2 hr postoperatively, no statistical significant differences in pain scores could be shown for both groups. However, at 3 and 4 hr postoperatively, patients in the tenoxicam group experienced significantly (P < or = 0.05) less pain than those in the diclofenac sodium group. On the evening of the third postoperative day, the tenoxicam group of patients experienced significantly less pain (P < or = 0.05) than those in the diclofenac sodium group. This was again the case on the morning of the fourth postoperative day. On the fifth, sixth, and seventh postoperative days, the average pain scores for patients in the tenoxicam group were statistically significantly lower, both mornings and evenings, than those in the diclofenac sodium group of patients (P = 0.05).

A double-blind randomized comparison of midazolam alone and midazolam combined with ketamine for sedation of pediatric dental patients.

PURPOSE: The safety and efficacy of a new sedation technique for children having dental procedures under local anesthesia were evaluated. MATERIALS AND METHODS: One hundred children between the ages of 2 and 7 years who required sedation for dental procedures were administered either a combination of midazolam (0.35 mg/kg) and ketamine (5 mg/kg) or midazolam alone (1 mg/kg) rectally 30 minutes before removal to the dental chair. Pulse rate, respiratory rate, arterial pressure, oxygen saturation, adverse reactions, postoperative recovery, and behavior were recorded. RESULTS: Satisfactory sedation and anxiolysis were achieved with both drugs used in the study. When evaluating postoperative recovery, statistically significantly more children receiving midazolam alone were fully awake on admission to the recovery room and 30 minutes later. Results of physiologic monitoring, behavioral ratings, and adverse effects are reported. Excessive salivation occurred in 26% of children receiving the combination of drugs, compared with 14% receiving midazolam alone. Seven (14%) of the children receiving the combination of drugs hallucinated, compared with 21 (42%) receiving midazolam alone. Both drug groups had reliably good anxiolysis and sedation without loss of respiratory drive or protective airway reflexes. CONCLUSION: The use of a combination of midazolam and ketamine or midazolam alone is a safe, effective, and practical approach to managing children for minor dental procedures under local anesthesia. With this technique, advanced airway management proficiency is recommended.

An evaluation of the effect of oral ketamine and standard oral premedication in the sedation of paediatric dental patients.

We compared the effectiveness of ketamine with standard oral premedication (SOP) in 60 children, 2-7 years of age, sedated orally for dental treatment under local anaesthesia. Children were assigned randomly to receive either 12.5 mg/kg ketamine or 0.5 ml/kg of SOP orally 60 min before the dental procedure. Pulse rate, systolic, diastolic and mean arterial pressures, respiratory rates and blood oxygen saturation were recorded prior to drug administration, 60 min thereafter and immediately before the dental procedure. Anxiety levels were measured at the same time intervals. The level of sedation was measured 60 min after drug administration. No significant differences were found in the anxiety levels between the groups 60 min after oral administration. The level of sedation in both groups before surgery was excellent. Operator evaluation for overall effectiveness of treatment showed that sedation was very good in 60 per cent of children in the ketamine group compared with 20 per cent in the SOP group. More children in the ketamine group were better sedated (p < 0.05). Both premedicants produce good sedation and anxiolysis 60 min after premedication and immediately before the surgical procedure.

Epidemiology and control of schistosomiasis mansoni in communities living on the Cuando River floodplain of East Caprivi, Namibia.

The Cuando River area of eastern Caprivi, Namibia, is highly endemic for Schistosoma mansoni whereas S. haematobium transmission, due to the scarcity of its intermediate host snail, Bulinus africanus, does not occur. Chemotherapy (6-monthly blanket treatments with praziquantel) combined with focal mollusciciding (monthly application of niclosamide) was used in a project in the area to control the disease. Although as many adults and pre-school children as possible were tested and treated, the project concentrated largely on school-age children. It took 3 years for prevalence to decline from > 80% to 20% because of a lack of proper sanitary facilities and piped water supplies and high rates of absenteeism and re-infection. However, intensity of infection decreased more rapidly, from an arithmetic mean of > 200 to < 5 eggs/g faeces. Hepatomegaly was common among school children when the project started but could be seen in only a small percentage of them after 3 years of control. Neither the bovine schistosome, S. mattheei, nor the lechwe schistosomes, S. margrebowiei and S. leiperi, were observed in the excreta of humans living in the area.

Prevalence of viral infections in Mozambican refugees in Swaziland.

The seroprevalence for antibodies to HIV-1, HTLV-1, hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis E virus (HEV) were determined in a large group of Mozambican refugees living in Swaziland. Serum samples were collected from a total of 398 refugees located in the two camps (Ndzevane and Malindza). The prevalence for antibodies in the two camps were as follows: Ndzevane: 1.2% (HIV-1); 2.8% (HTLV-1); 0.3% (HCV); 4% (HEV) and 66% for any HBV marker. Malindza: 10.8% (HIV-1); 5.4% (HTLV-1); nil (HCV); 2% (HEV) and 65.7% for any HBV marker. The difference in the HIV-1 seroprevalence between the two camps was statistically highly significant. The phenomenon is possibly related to the location of the Malindza camp in the northern most populous area of Swaziland, resulting in more frequent contact between refugees and the local Swazi population.

Serologic markers for hepatitis B virus and hepatitis A virus in Bushmen in West Caprivi, Namibia.

A community based sero-epidemiological study was undertaken to determine the age specific prevalence rates of hepatitis A virus (HAV) and hepatitis B virus (HBV) infection in a band of Bushmen in the West Caprivi, Namibia. All children tested and all but two of the adults tested showed the presence of anti-HAV antibodies. Nineteen individuals (18%) were positive for HBsAg and 65 (61%) individuals had serologic evidence of past exposure to HBV infection.

Low prevalence of human T lymphotropic virus type I in !Kung San in Bushmanland, Namibia.

Antibodies to human immunodeficiency virus 1 (HIV-1) and human T lymphotropic virus type 1 (HTLV-I) have been identified in various population groups living in southern and central Africa. Sera from 291 !Kung Bushmen in Bushmanland, Namibia were examined for the presence of antibodies to HIV-1 and HIV-2 and to HTLV-I. Initial screening for HIV-1/2 by two enzyme-linked immunosorbent assays (ELISAs) revealed evidence of past exposure in four individuals. However, no HIV-1/2 infection could be confirmed by a particle agglutination assay, a recombinant ELISA, or by Western blot for HIV-1 and HIV-2. Indeterminate Western blot profiles (with a p55 for each and either a p25 or p18 band) existed for all four HIV-1-reactive sera. Eight sera were reactive in the HTLV-I ELISA, although only five were positive on a second ELISA. Only three of the five HTLV-I-reactive sera could be confirmed by Western blot.

The usefulness of cerebrospinal fluid tests for neurosyphilis.

To determine the usefulness of cerebrospinal fluid (CSF) tests for syphilis at a large academic hospital, clinical and laboratory data on 644 patients in whom such testing was requested over a 12-month period were analysed. In 198 cases (31%) the Treponema pallidum haemagglutination (TPHA) screening test could not be performed because of insufficient fluid. Thirty-eight of the remaining patients were diagnosed as having active neurosyphilis. Examination of 22 files of patients who had a positive TPHA and fluorescent treponemal antibody absorption (FTA-Abs) test together with a negative CSF Venereal Disease Research Laboratory (VDRL) test revealed that other CSF measures indicating disease activity (CSF protein, cells or IgG index) were not utilised optimally. In 10 (45%) of these patients neurosyphilis was not diagnosed despite either abnormal or incomplete CSF biochemical analysis, indicating that if the CSF VDRL is used as the sole marker for disease activity, some cases of neurosyphilis are likely to be missed.

Prevalence of hepatitis B in !Kung (San) children from Bushmanland, Namibia.

Serum samples from 248 predominantly !Kung children (aged 5-19 years) attending various bush schools and a clinic in Bushmanland, northern Namibia were examined for the presence of hepatitis B virus (HBV) markers by radioimmunoassay. HBsAg was detected in 18 (7.3%) children while 117 (47.6%) showed one or more markers of HBV infection. These prevalence rates are lower than those of the closely situated territory of Kavango to the north and East Caprivi to the north-east. No significant difference in HBs antigenaemia between !Kung boys and girls was found (p > 0.05). However, HBs antigenaemia was found to vary between children in different bush schools. A significantly higher number of children attending the Omatako bush school were positive for HBsAg than the number attending the Luhebu bush school (p < 0.0167). These local variations could assist in the initial targeting of HBV vaccine to high-risk areas. In situ investigations of hyperendemic foci in Bushmanland, Namibia should help to elucidate the variation in HBs antigenaemia and the factors responsible for transmission of HBV.

Ubombo and the site of David Bruce's discovery of Trypanosoma brucei.

The site and remains believed to be those of the camp where Sir David Bruce and his wife Mary worked between 1894 and 1897, and where Bruce discovered the causative agent of nagana and its transmission by the tsetse fly, have recently been discovered at the small village of Ubombo in northern KwaZulu (Zululand), South Africa. The site where these remnants were found fits the meagre, albeit significant, information presented by Bruce in his writings on the location of the camp.

An open comparative study of the analgesic effects of tenoxicam and diclofenac sodium after third molar surgery.

Tenoxicam and diclofenac sodium were compared as analgesics following the surgical removal of third molars. Twenty-five patients between the ages 17 and 29 years were randomly allocated into two groups. Patients in group A received a single intraoperative intravenous (i.v.) injection of 20 mg of tenoxicam followed by a 20-mg tablet given the evening after the operation; thereafter, one 20-mg tablet was given once daily for the next 6 days. Group B received a single intraoperative intramuscular injection of 75 mg of diclofenac sodium followed by a 50-mg tablet 4 to 6 hours postoperatively and during the evening; thereafter, a 50-mg tablet was taken three times daily for the next 6 days. Pain was postoperatively measured hourly for 4 hours and later in the evening. Pain was also measured in the mornings and evenings for the next 6 days. The highest pain scores were obtained 1 hour postoperatively for both groups. During the first 3 hours following administration, patients in the tenoxicam group experienced significantly more pain than those in the diclofenac group. Preoperatively, both treatments showed identical efficacy after 3 hours. It is therefore suggested that a 40-mg dose of i.v. tenoxicam should be administered at induction of anesthesia to achieve a higher level of analgesia in the immediate postoperative phase.