Displaying publications 1 - 20 of 662 in total

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  1. Rees RJ
    Bibl Tuberc, 1970;26:189-232.
    PMID: 4244234
    Matched MeSH terms: Disease Models, Animal
  2. Walker JS, Cadigan FC, Vosdingh RA, Chye CT
    J Infect Dis, 1973 Aug;128(2):223-6.
    PMID: 4198721
    Matched MeSH terms: Disease Models, Animal*
  3. Petrányi G, Mieth H, Leitner I
    PMID: 1221502
    Infective larvae of Brugia malayi subperiodic obtained by dissection of infected Aedes togoi were injected subcutaneously into the scrotal region of Mastomys natalensis. From altogether 58 infected male M. natalensis 81% showed consistently or intermittently detectable microfilaraemia, whereas in 19% of the animals no microfilaraemia could be detected at any stage. The mean prepatent period was 136 days; the microfilarial density varied from 1 to 535 per 20 c. mm blood. In those animlas with consistently detectable and in general higher microfilaraemia an average of 13.1 live adult worms were found, against an average of 6.4 adult worms in animals with intermittent detectable and in general lower microfilaraemia. An average of 1.5 worms was found in animals which at no stage showed detectable microfilaraemia. A correlation between worm burden and prepatent period could be observed in the individual groups. From the total of 520 live adult worms recovered at necropsy, 37% were found in the lungs, 29% in the parenchyma of the testes and 34% in the lymphatic system. 47% of live fertile female worms were found in the lymphatic system, whereas the majority, i.e; 52% of infertile female worms were detected in the lungs. In addition, 380 encapsulated dead worms were found, most of them (98%) in the lymphatic system. 61% of a total of 900 live and dead worms were found in the region of the lymphatic system.
    Matched MeSH terms: Disease Models, Animal*
  4. Palmieri JR, Krishnasamy M, Sullivan JT
    PMID: 415371
    Matched MeSH terms: Disease Models, Animal
  5. Heisey GB, Gan E, Shirai A, Groves MG
    Lab. Anim. Sci., 1981 Jun;31(3):289-91.
    PMID: 6790836
    Using an indirect immunofluorescence technique, sera from 113 cynomolgus monkeys (Macaca fascicularis), trapped in Peninsular Malaysia, were screened for the presence of antibody to six prototype strains of Rickettsia tsutsugamushi combined into three polyvalent groupings: I--Karp, TA716, and TA763; II--Gilliam; and III--TA678 and TH1817. Fifteen percent (17/113) of the monkeys had antibody titers greater than or equal to 1:50 to one or more of the antigenic groups. Although a titer greater than or equal to 1:150 is generally considered indicative or prior Rickettsia tsutsugamushi infection, we selected a less than 1:25 titer as a conservative standard to insure non-infected animals. Using this criterion, 62 (55%) of the 113 monkeys were accepted for use in scrub typhus studies. The high prevalence of antibody to scrub typhus in the semi-arboreal cynomolgus monkey is in marked contrast to the low prevalence reported in the strictly arboreal silvered leaf monkeys (Presbytis cristatus). The results of this study indicate that cynomolgus monkeys should be rigorously screened for evidence of prior infection before they are included in experimental scrub typhus studies.
    Matched MeSH terms: Disease Models, Animal
  6. Chiang GL, Cheong WH, Eng KL, Samarawickrema WA
    J. Helminthol., 1987 Dec;61(4):349-53.
    PMID: 3437114
    This paper reports the experimental transmission of a bird parasite into jirds. Infective larvae of Cardiofilaria nilesi obtained from laboratory colonized Coquillettidia crassipes mosquitoes which had fed on an infected chicken were inoculated subcutaneously into jirds. The number of larvae per jird varied from 10 to 228. Microfilaraemia appeared 22 to 89 days after inoculation of the infective larvae. Experiments were carried out with 24 jirds through six generations extending over a period of 22 months and 17 produced patent infections. At present 8 infected jirds are being maintained in the laboratory; their patent periods ranging from 6 to 13 months. However, the longest patent period observed was about thirteen months. The percentage of adults recovered in autopsied jirds ranged from 0 to 40 with an average of 16. The chicken showed a microfilarial periodicity with the peak microfilarial density around 2200 hours. However, in jirds there was a change in sub-periodicity. This model in the jird may be very useful for the screening of filaricides and in immunological work.
    Matched MeSH terms: Disease Models, Animal
  7. Sinniah R, Sinniah D, Chia LS, Baskaran G
    J Pathol, 1989 Nov;159(3):255-64.
    PMID: 2593049
    The aetiology and pathogenesis of Reye's syndrome (RS) are incompletely understood. A number of environmental toxins and biological agents, including viruses, have been postulated to cause RS, either acting alone or synergistically. Most investigations have suggested that the primary insult is in the liver mitochondria, leading to a complex biochemical catastrophe, with death from encephalopathy. Margosa oil (MO), a long-chain fatty acid compound, has been shown to cause a Reye-like syndrome with death from hepatoencephalopathy, in children in Malaysia and India. The present time-course study performed in MO-administered mice showed the development of hepatic lesions with many features of RS. MO acts rapidly, within 30 min, on the nuclei of hepatocytes inducing mitoses and binucleated cells. This is followed by mitochondrial injury, with swelling, rarefaction of matrix, loss of dense bodies, pleomorphism, and loss of ribosomes starting at 60 min. There is loss of liver glycogen, and proliferation and hypertrophy of the endoplasmic reticulum (ER), followed by the presence of lipid droplets in the hyaloplasm, and globules within dilated cisterns of the ER. Additional fatty acids from lipolysis of body adipocytes, and fat globules from intestinal MO ingestion further aggravate the liver fatty change. There is evidence of fat globule ingestion by endocytosis into hepatocytes at the level of the sinusoids. The development of microvesicular liver steatosis and glycogen depletion due to involvement of liver cell organelles occur rapidly as in RS.
    Matched MeSH terms: Disease Models, Animal*
  8. Karim QN, Finn GY, Easmon CS, Dangor Y, Dance DA, Ngeow YF, et al.
    Genitourin Med, 1989 Dec;65(6):361-5.
    PMID: 2693334
    A monoclonal antibody raised against Haemophilus ducreyi was tested for its sensitivity and specificity as an immunofluorescence (IF) reagent using simulated vaginal smears containing H. ducreyi, smears taken from skin lesions of mice infected with H. ducreyi and patients from South Africa, Thailand and Malaysia with clinically diagnosed chancroid. The IF test was more sensitive than culture or Gram staining in the simulated smears, theoretically detecting less than 4 organisms/sample. It detected H. ducreyi in 95% of the animal lesions compared with 14% detected by culture. Immunofluorescence testing identified over 90% of culture-positive cases of chancroid but also detected organisms in some culture-negative cases where clinical evidence for the diagnosis was strong. These results suggest that this antibody may provide a simple, rapid and sensitive means of detecting H. ducreyi in cases of chancroid.
    Matched MeSH terms: Disease Models, Animal
  9. Mak JW, Choong MF, Lam PL, Suresh K
    Acta Trop, 1990 May;47(4):223-6.
    PMID: 1973024
    The leaf-monkeys, Presbytis cristata and Presbytis melalophos, experimentally infected with subperiodic Brugia malayi, have been used for studies on the pathoimmunology of the infection and the screening of potential filaricides during the last 6-8 years, and considerable information on the pattern of microfilaraemia and adult worm recoveries have been obtained. The prepatent periods in 97 P. cristata and 45 P. melalophos, each infected with about 200 infective larvae, were similar, these being approximately 70 and 68 days respectively. Although all infected animals became microfilaraemic, the peak geometric mean count was much higher in P. cristata than in P. melalophos, this being 182.0 and 65.8 per ml blood respectively. Mean adult worm recovery expressed as the percentage of the infective dose was 4.7% and 2.5%, respectively. Most worms were recovered from the sacral nodes/thoracic duct or inguinal lymph nodes in these animals. In view of the higher worm recovery and the higher peak microfilaraemia attained, it is concluded that P. cristata is a better model for the infection than P. melalophos.
    Matched MeSH terms: Disease Models, Animal*
  10. Mak JW, Lam PL, Choong MF, Suresh K
    J. Helminthol., 1990 Jun;64(2):96-9.
    PMID: 2387979
    The known filaricides, suramin and diethylcarbamazine citrate, were tested against subperiodic Brugia malayi infection in the leaf-monkey, Presbytis cristata. As expected, intravenous suramin at 10 mg/kg daily x 5 days or 17 mg/kg weekly x 5 weeks, did not show any microfilaricidal activity, but substantially reduced the recovery of live adult worms to 50.6% and 13.6% of controls respectively. Oral diethylcarbamazine citrate at 6 mg/kg daily x 6 or 10 days reduced final microfilarial counts to 30% of initial counts four weeks post-treatment and adult worm recovery was reduced to 4.5% and 0% of controls respectively. Although the antifilarial activity of these drugs against the infection in this non-human primate model appears to be similar to that seen in man, these results have to be confirmed using larger groups of animals.
    Matched MeSH terms: Disease Models, Animal
  11. Sinniah D, Sinniah R, Baskaran G, Pathmanathan R, Yamashita F, Yoshino M
    Acta Paediatr Jpn, 1990 Aug;32(4):462-8.
    PMID: 2288230
    Glucose and steroids have been used in the treatment of children with Reye's syndrome, while carnitine and coenzyme Q10 have been the subject of some recent studies which suggest that these agents may have a role in the treatment of Reye's syndrome and Reye-like syndrome due to margosa oil poisoning. Because of the paucity of causes of Reye's syndrome seen at any one centre, the clinical variability of the disease, and limited knowledge of definite aetiologic factors, controlled clinical trials are not easy to carry out or to interpret in human cases. These caveats were overcome by evaluation of these four treatment modalities in an established margosa-oil-induced animal model of Reye's syndrome. Effectiveness of the treatment modalities was determined from clinical response and histopathologic parameters (grading of light microscopic fatty changes and ultrastructural changes in the hepatocytes). Results show that carnitine per se produces a small improvement in survival, but statistically, more significant benefit is seen with glucose administration. Carnitine plus 10% dextrose appears to produce better results. Evaluation of coenzyme Q10 and carnitine on histopathologic parameters in the liver after a sublethal dose of margosa oil showed no obvious ameliorating effect on liver pathology. Steroids (dexamethasone/methylprednisolone) had no beneficial effects in reducing mortality, affecting glycogen storage or lipid accumulation. Changes in the mitochondria, ribosomes and endoplasmic reticulum were unaltered from the groups treated with margosa oil alone. While glucose and carnitine supplements appear to be beneficial, the other modes of therapy do not seem to hold much promise in the treatment of Reye-like syndrome in the margosa-oil-induced animal model.
    Matched MeSH terms: Disease Models, Animal
  12. Leong YK, Awang A
    Microbiol. Immunol., 1990;34(2):153-62.
    PMID: 2161071
    Rotaviral infections in cynomolgus monkeys (Macaca fasicularis) were studied to ascertain its suitability as a model of infection and diarrhea caused by group A human rotaviruses. Formula-fed monkeys were used as they could be observed closely. Experimental rotaviral infection of cynomolgus monkeys was age-dependent; only young monkeys were readily infected. Formula-fed newborns were readily infected with cell-culture-adapted human (WA) and simian (SA11) viruses and with a rotavirus from a human fecal specimen. However, diarrhea was detected only in very young animals. A number of rotaviral shedding patterns as a function of time were observed. Although there was no typical viral shedding pattern which represented exclusive association of viral infection with diarrhea, the initial level of viral excretion and the maximum level of viral shedding attained were much higher in animals with diarrhea. Seroconversion occurred in less than half of the inoculated animals. The presence of maternal rotaviral antibodies did not prevent infection or diarrhea.
    Matched MeSH terms: Disease Models, Animal*
  13. Mak JW, Choong MF, Suresh K, Lam PL
    Parasitol Res, 1990;76(8):689-91.
    PMID: 2251244
    Presbytis cristata monkeys infected through the inoculation of between 200 and 400 subperiodic Brugia malayi infective larvae (L3) in the right thigh, in both thighs or in the dorsum of the right foot were followed up for varying periods of up to about 8 months after infection. All 148 inoculated animals became patent, with mean prepatent periods being between 66 and 76 days. In animals injected in the thigh, the patterns of microfilaraemia were similar, there being a rapid rise in the geometric mean counts (GMCs) of microfilariae during the first 10-12 weeks of patency, which then plateaued at levels of greater than 1000/ml. Adult worm recovery, expressed as the percentage of the infective dose, was significantly higher in animals injected with 100 L3 in each thigh, being 9.4% as compared with 2.8%-4.8% in other groups. It is therefore recommended that animals should be injected with 100 L3 in each thigh and that the testing of potential filaricides in this model be carried out during the phase of rapid increase in microfilaraemia to ensure that any microfilaricidal effect can easily be detected.
    Matched MeSH terms: Disease Models, Animal*
  14. Mak JW, Navaratnam V, Ramachandran CP
    Ann Trop Med Parasitol, 1991 Feb;85(1):131-7.
    PMID: 1888210
    An intense global collaborative effort under the leadership of the Steering Committee of the Filariasis Scientific Working Group of the Tropical Diseases Research Programme, World Health Organization, has brought together researchers, pharmaceutical chemists and clinicians in the development and search for antifilarial compounds which are more effective and more convenient to administer than diethylcarbamazine citrate, the current drug of choice for lymphatic filariasis. The Brugia spp.-rodent model has been used extensively for the primary screening and B. pahangi infections in the dog or cat for the secondary screening, of potential filaricides. Recently, the leaf-monkey (Presbytis spp.) infected with subperiodic B. malayi or Wuchereria kalimantani has been used for the tertiary evaluation and pharmacokinetic studies of compounds which have shown effectiveness in the primary and secondary screens. Both P. cristata and P. melalophos are extremely susceptible to subperiodic B. malayi infection, but the former is a better host as a higher peak microfilaremia and adult worm recovery rate were obtained. Although more than 30 potential filaricides have been evaluated in the tertiary screen, only a few compounds have shown some promise against lymphatic filariasis. CGP 20376, a 5-methoxyl-6-dithiocarbamic-S-(2-carboxy-ethyl) ester derivative of benzothiazole, had complete adulticidal and microfilaricidal activities against the parasite at a single oral dose of 20 mg kg-1. However, as the compound or its metabolites caused hepatotoxicity, its clinical use in the present formulation is not recommended.(ABSTRACT TRUNCATED AT 250 WORDS)
    Matched MeSH terms: Disease Models, Animal
  15. Choong MF, Mak JW
    Trop. Med. Parasitol., 1991 Mar;42(1):71-2.
    PMID: 1675809
    The Presbytis cristata--Brugia malayi model, now established as a reliable non-human primate model for the experimental screening of potential filaricides, was monitored at monthly intervals for changes in the liver and renal function tests and also for alkaline phosphatase levels during infection. Animals infected with 200-400 infective larvae became patient at 50-90 days post-infection and geometric mean microfilarial counts were above 1000 per ml from the fourth month onwards. There were no significant changes in the biochemical parameters monitored throughout the period of observation. This is an important observation as any changes seen in these parameters during experimental drug studies can be attributed to drug reaction or toxicity and this will be invaluable in decision making as to drug safety.
    Matched MeSH terms: Disease Models, Animal*
  16. Choong MF, Mak JW
    PMID: 1948274
    Hematological changes were monitored in the leaf-monkey, Presbytis cristata, infected experimentally with 200 subperiodic Brugia malayi infective larvae. Prepatent periods were 54-86 days and peak microfilarial geometric mean counts (GMCs) were 1324 per ml blood. Total leukocyte and differential counts were measured at pre-infection, and then at weakly intervals before and during patency. Blood eosinophil level increased to about thrice the initial level at 3 weeks post-infection and this was maintained for the next 13 weeks before it started to rise again, increasing to more than 5 times the initial level at 20 weeks post-infection. The observed pattern of eosinophilia is probably related to the level of microfilaremia and the destruction of microfilariae in the spleen. There was no significant change in the total leukocyte counts during the period of observation.
    Matched MeSH terms: Disease Models, Animal
  17. Shekhar KC, Pathmanathan R
    PMID: 1523486
    Schistosoma malayensis Sp N is a putative new species of schistosome discovered in Peninsular Malaysia in 1973. This paper comprises the first report on the detailed gastrointestinal pathology present in rabbits infected with strains of the parasite. Two different strains of schistosome--the Baling and Koyan strains--from two different ecosystems were used to infect inbred rabbits and the resulting pathophysiology was studied. Our results showed that the Baling strain of S. malayensis was more virulent than the Koyan strain and produced nodular, segmental circumferential lesions and large bilharziomas measuring 1-7 cm in diameter in the distal jejunum, ileum and the ileo-caecal junction. The findings indicate that the Baling strain of S. malayensis was more pathogenic for rabbits as compared with the Koyan strain--in relation to the gross pathology of the gut and the tissue egg load. Earlier reports have shown that rabbits infected with S. japonicum induces significant intestinal lesions in rabbits (Cheever et al, 1980 a,b) but these animals are refractory to infection with S. mekongi (Byram and Lichtenberg, 1980). Our studies show that the two strains of S. malayensis adapted well in rabbits. It is also established that in rabbits, the virulence of the Baling strain of S. malayensis is greater than that of S. mekongi and approximates that of S. japonicum.
    Matched MeSH terms: Disease Models, Animal
  18. Abdul Samad S, Yasin MS, Arumugham G, Yap KL
    Malays J Pathol, 1993 Dec;15(2):119-23.
    PMID: 8065172
    An invasive aspergillosis model in rabbits was attempted using 3 concentrations of A. fumigatus conidia. Conidia concentrations of 1 x 10(6), 1 x 10(7) and 1 x 10(8) were inoculated intravenously into rabbits. The severity of infection was directly proportional to the inoculum size of the conidia. Aspergillus fumigatus was isolated from livers, kidneys, spleens, hearts and lungs of infected rabbits at a rate of 82%, 75%, 57%, 54% and 32% respectively. Cultures of urine specimens taken by bladder tap were positive for A. fumigatus in 30% of the rabbits tested. Blood cultures using the Bactec Fungal System (Becton Dickinson Corp., USA) failed to isolate A. fumigatus in 20 rabbits with biopsy-proven invasive apergillosis. Active infection with high fungal tissue burden occurred between 2-4 days after infection in rabbits inoculated with 1 x 10(7) conidia.
    Matched MeSH terms: Disease Models, Animal
  19. Mak JW
    PMID: 7973952
    The lymphatic filarial parasites which affect about 90 million people worldwide have similar host-parasite relationships in man. They are all able to survive, reproduce and cause chronic infections if they can successfully evade the protective responses of the host. Studies to investigate the wide spectrum of clinical manifestations of the infection even among those living in similar endemic areas and with presumed equal exposure to infective larvae, have been hampered by the lack of animal models showing similar host-parasite responses. The recent use of the nude mouse infected with Brugia spp, and the leaf-monkey (Presbytis spp) infected with B. malayi or Wuchereria spp for the study of immune responses and the associated pathology of these infections, has elucidated some of the host protective immune responses as well as the associated immunopathological reactions. The successfully entrenched parasite elicits minimal reactions and pathology, but with the onset of effective host responses, whether assisted by chemotherapy, development of protective immunity or both, severe inflammatory responses may occur. The role of such immune mediated response in determining subsequent pathology will probably be dependent on the frequency and duration of these episodes, but these have yet to be defined. Prenatal and perinatal sensitization by filarial antigens are postulated to result in tolerance and/or modification of immune responses to subsequent infections. A role for genetic predisposition to certain clinical outcomes, for example, the development of elephantiasis, has been postulated but needs further study. Advances have also been achieved in defining those parasite antigens/products involved in eliciting or suppressing protective and other immune responses.(ABSTRACT TRUNCATED AT 250 WORDS)
    Matched MeSH terms: Disease Models, Animal
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