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Biomedical subjects

G Dreyer

Publications and source records attributed to G Dreyer.

At least 55 records · Page 3Linked to original sources
PubMed1991

In vitro differentiation of Wuchereria bancrofti (Filariidae).

Wuchereria bancrofti microfilariae were isolated from blood of infected individuals and cultured in vitro under several conditions. RPMI 1640 and TC-199 media supplemented with fetal or human serum were able to support the microfilariae for periods up to 35 days at 37 degrees C (viability greater than 85%). In contrast, in minimal essential medium the microfilariae did not survive for more than 48 h. In cultures kept at 28 degrees C, where viability was much lower (approximately 10% on day 15), microfilariae differentiated into type IV larvae ("sausage" form). The in vitro maintainance of microfilarial larval forms is particularly important in the case of W. bancrofti due to the absence of an experimental model for the disease.

Animals↗
PubMed1990

Immunocytochemical localization of surface antigens in microfilariae of Wuchereria bancrofti.

Antigenic sites were localized on the surface structure (sheath and cuticle) of microfilariae of Wuchereria bancrofti using sera from microfilaraemic and amicrofilaraemic patients using antibodies associated to colloidal gold particles and transmission electron microscopy. No labeling was observed on the surface of intact parasites. Microfilariae without the sheath and isolated sheath were obtained by ultrasound treatment. Using these preparations labeling of the inner portion of the sheath was observed when sera from amicrofilaraemic patients were used. Labeling of the cuticle surface was observed mainly in the regions of the cuticular annulations.

Animals↗
PubMed1989

Inappropriateness of the association of diphenhydramine with diethylcarbamazine for the treatment of lymphatic filariasis.

The efficacy of diphenhydramine, an antihistaminic, in preventing adverse reactions to diethylcarbamazine (DEC) in patients infected with Wuchereria bancrofti, was assessed by treating 50 patients with both drugs and 57 with DEC alone. It was found to be ineffective, and to cause drowsiness in all those unaffected by adverse reactions. The authors conclude that the combined use of both drugs for the treatment of Bancroftian filariasis, which is the usual practice in Brazil, should be avoided.

Adolescent↗
PubMed1989

Fine structure and localization of anionic sites on the surface of microfilaria of Wuchereria bancrofti.

The fine structure of the sheath and the cuticle of microfilaria of Wuchereria bancrofti was analysed and the results obtained were compared with those from other filarial parasites. Cationized ferritin particles bind to the surface of the sheath and the epicuticle. No binding of colloidal iron hydroxyde particles to the microfilaria surface was observed. Reaction product indicative of carbohydrates containing vic-glycol groups was not observed in thin sections of microfilaria submitted to the periodic acid-thiosemicarbazide-silver proteinate technique. The results obtained are discussed in relation to previous studies using lectins.

Animals↗
PubMed1983

T-cell hybrids. IV. One of parental cell lines is dominant in determining membrane characteristics of hybrid cells.

Membrane characteristics of parental thymic lymphoma cells (BW5147, EL-4R) and their hybrids (BH2) derived by PEG-promoted cell fusion were compared. Isoelectric focusing of the cell populations, titration of membrane proton binding groups and quantitative examination of cell-substrate adhesiveness indicated that the BW5147 cells behaved as dominant in determining cell membrane characteristics of the BH2 hybrids.

Animals↗
PubMed1982

The use of doxycycline to control heartwater in sheep.

A ready-to-inject solution, containing 100 mg/ml doxycycline was used. Artificially infected sheep were divided into 2 groups: a control group consisting of 10 animals, and a treated group consisting of 12 animals. Doxycycline was administered intramuscularly to the animals in the treated group at a dosage rate of 2 mg/kg body mass. All the treated animals recovered. One control animal recovered spontaneously, the others all died.

Animals↗
PubMed1981

Oxytetracycline plasma levels in dogs after intramuscular administration of two formulations.

Plasma levels of oxytetracycline in dogs were compared in a cross-over study. A long-acting formulation and a polyvinylpyrrolidone formulation were injected intramuscularly. Symptoms of histamine release were recorded after the use of polyvinylpyrrolidone formulation. Higher peak plasma concentrations but shorter maintenance of therapeutic concentrations were recorded in the case of the polyvinylpyrrolidone formulation than with the long-acting formulation.

Animals↗
PubMed1981

The choleretic action of clanobutin in dogs.

After cannulation of the bile duct in anaesthetised dogs, clanobutin was injected intravenously. Samples were collected for periods of 15 min. Arterial and venous blood pressures as well as the electrocardiogram were recorded during the experiment. There was a slight increase in arterial and central venous pressure during the trial. Heart rate slightly decreased with a slight increase in ventricular ectopic beats. In the first 15 min after bile flow increased by 260%. The choleretic action lasted for 1,5 h. The concentration of sodium, potassium and magnesium in the bile followed a similar pattern to that of the volume. Bilirubin and calcium excretion showed a sharp increase within the first 15 min after administration. Thereafter there was a sharp drop and 30 min after administration the concentration was below the control value.

Animals↗
PubMedDate not supplied

Tolerance of diethylcarbamazine by microfilaraemic and amicrofilaraemic individuals in an endemic area of Bancroftian filariasis, Recife, Brazil.

To determine the tolerance to diethylcarbamazine (DEC) treatment of patients with Bancroftian filariasis, 193 individuals (138 asymptomatic microfilaraemic, 30 amicrofilaraemic diseased patients and 25 asymptomatic amicrofilaraemic endemic residents) were enrolled in a prospective trial with different dose schedules, in a hospital and outpatient clinic setting in Brazil. Systemic adverse reactions, localized adverse reactions, and side effects, related to microfilariae, adult worms and the drug itself, were evaluated. Systemic reactions occurred irrespective of the DEC dose and schedule in about 40% of the microfilariae carriers, but not in amicrofilaraemic diseased patients or residents; they usually consisted of microscopic haematuria, followed by fever and malaise. Localized reactions were manifested by the appearance of inflammatory reactions, mainly in the scrotal area. Nodules containing degenerating adult worms developed mainly in the scrotal lymphatics of microfilaraemic patients, diseased amicrofilaraemic patients, and residents. Drowsiness, which increased with higher doses of DEC, was the most common side effect in both microfilaraemic and amicrofilaraemic individuals, followed by nausea and gastric upset. The results indicate that the occurrence of systemic and local adverse reactions was unrelated to either the dose of DEC or the pretreatment microfilarial density. The severity of systemic reactions was proportional to the microfilarial density. Side effects were dependent on the drug dosage irrespective of infection status.

Adolescent↗
PubMedDate not supplied

Direct assessment of the adulticidal efficacy of a single dose of ivermectin in bancroftian filariasis.

Although the potent microfilaricidal activity of ivermectin is well established, its efficacy against adult Wuchereria bancrofti is unknown. We used longitudinal ultrasound examinations for periods of 3-9 months to assess directly the macrofilaricidal effect of a single 400 micrograms/kg dose of ivermectin in 15 men from Recife, Brazil who were infected with W. bancrofti. Before treatment, microfilarial densities ranged from 3 to 3098 microfilariae per mL of blood, and movements characteristic of the living adult worm (the 'filaria dance sign') were observed by ultrasound examination of the scrotal lymphatic vessels in all 15 men. Following treatment, microfilarial density was markedly reduced in all men, but the filaria dance sign remained unchanged in both location and pattern. Eight months after treatment, a dilated lymphatic vessel was surgically removed from one patient at the site of the filaria dance sign, and 3 intact adult worms were released. When given as a single 400 micrograms/kg dose, ivermectin had no observable effect on adult W. bancrofti. Therefore, prolonged suppression of microfilaraemia following treatment with ivermectin cannot be explained by a macrofilaricidal effect of the drug. Ultrasound is a valuable new tool for directly and rapidly assessing the macrofilaricidal efficacy of antifilarial drugs in lymphatic filariasis.

Adult↗
PubMedDate not supplied

Syndrome resembling tropical pulmonary eosinophilia but of non-filarial aetiology: serological findings with filarial antigens.

Although the tropical pulmonary eosinophilia (TPE) syndrome of filarial aetiology has very distinctive clinical and immunological features, its clinical profile is not unique; other helminths sometimes induce similar presentations. We carefully evaluated 7 individuals with non-filarial TPE-like syndromes and found that serological tests based on detection of 'antifilarial' immunoglobulin (Ig) G, IgG4, and IgE antibodies that are usually considered diagnostic for filarial TPE were equally elevated in patients with non-filarial, TPE-like syndromes and were therefore unhelpful diagnostically. The apparent reasons were immunological hyper-responsiveness of such individuals and the shared (i.e., cross-reactive) antigenicity found in the filarial antigen preparations used routinely for diagnosis. Because appropriate treatment for those different pulmonary eosinophilia conditions requires different drugs and management, and because delay in effective treatment results in significant morbidity in such patients, diagnostic capabilities must be improved by identifying and obtaining unique antigens that can serologically discriminate between filarial TPE and other similar, but non-filarial, pulmonary eosinophilia syndromes.

Adult↗
PubMedDate not supplied

Comparative efficacy of three different diethylcarbamazine regimens in lymphatic filariasis.

To assess the efficacy of diethylcarbamazine (DEC) in clearing Wuchereria bancrofti microfilariae (mf) from the circulation, we conducted a single blind hospital-based therapeutic trial of 3 DEC regimens. All patients were assessed by filtration of 1 mL of venous blood taken before and 1, 3, 6 and 12 months after DEC administration. The efficacy of a 12 d course of 6 mg/kg DEC once daily was identical to that of a similar course with 2 mg/kg given 3 times daily, indicating that split-dose treatment does not improve mf clearance over single daily drug administration. Microfilarial densities in patients treated only once with 6 mg/kg DEC remained significantly higher at 1, 3, and 6 months after treatment. However, all 3 treatment regimens proved equally effective in controlling microfilaraemia after 12 months, when 41, 42 and 40% of patients in the 3 treatment groups were amicrofilaraemic. These results suggest that a single DEC dose of 6 mg/kg administered annually or biannually may be a suitable regimen to control bancroftian filariasis in Recife, Brazil.

Adolescent↗