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Biomedical subjects

M M Wong

Publications and source records attributed to M M Wong.

At least 55 records · Page 3Linked to original sources
PubMed1980

Ferric chloride leach-electrolysis process for production of lead.

The U.S. Department of the Interior, Bureau of Mines, under a cost-sharing, cooperative research agreement with lead producers, is studying a process to eliminate sulfur oxide generation and to minimize lead emission in the production of lead. The new process consists of leaching lead sulfide concentrate with a ferric chloride-sodium chloride solution to produce lead chloride, and fused-salt electrolysis of lead chloride to produce lead metal and chlorine. The chlorine is used to regenerate ferric chloride in the leach solution. The study is being conducted in a process investigation unit which treats 750 lb of concentrate a day. This paper discusses the results of operation of the process investigation unit, data on lead monitoring, and the precautions employed to control lead levels in the workplace atmosphere. The monitoring data for the initial phase of the investigation show lead levels well within OSHA permissible exposure limits. Continued development is necessary before the process can be considered for implementation.

Chlorides↗
PubMed1979

In vitro susceptibilities of Naegleria fowleri strain HB-1 to selected antimicrobial agents, singly and in combination.

The overall prognosis of primary amoebic meningoencephalitis remains poor. The results of this study support previous finding that amphotericin B is the most efficacious drug against the Naegleria species in in vitro testing. In addition, the methyl ester of amphotericin B, a new derivative, also appears to be an effective agent. Of the drug combinations studied, amphotericin B plus minocycline and amphotericin B plus tetracycline showed synergy. The clinical significance of these findings remains to be determined.

Amoeba↗
PubMed1979

Experimental congenital infection of Toxoplasma gondii in Macaca arctoides.

Congenital toxoplasmosis was studied in Macaca arctoides as a model for primates. Time-mated female monkeys were assigned to 5 experimental groups and inoculated with 4 different strains of Toxoplasma gondii before pregnancy and during various stages of gestation. All monkeys showed a rise in indirect hemagglutination antibody (IHA) titers following infection, and some had demonstrable parasitemia. Of the 23 progeny, 2 were stillbirths and 2 died soon after birth, but only the one neonate born of a mother inoculated intrauterally succumbed to acute toxoplasmosis. No physical anomalies were observed in any of the progeny. The toxoplasms organism was not isolated from any of the placentas obtained nor from the cord blood. None of the tissues from the stillborn or infant monkeys that died were positive for toxoplasmosis by mouse inoculation. The live progeny were usually born with high IHA antibody titers which were usually soon lost, indicating presence of passively acquired maternal antibody. However, 2 babies, born of mothers infected with tissue cysts on day 79 and 149 of gestation, maintained moderate to high titers for about 8 and 19 months respectively, indicating that an active infection had taken place but no clinical disease was detected. Data obtained suggest that although certain developmental stages of the toxoplasma organism and of the fetus may favor the occurrence of congenital infection, very little neonatal disease results in this primate model.

Animals↗
PubMed1979

Indirect fluorescent antibody test in occult dirofilariasis.

Indirect fluorescent antibody titers to Dirofilaria immitis microfilaria (IFA-mf) and peripheral eosinophilia were recorded from 15 to 52 months in ten experimentally infected dogs with occult dirofilariasis (heartworm infection without microfilaremia). Five dogs which were experimentally sensitized with D immitis microfilaria did not exhibit microfilaremia after inoculation with infective-stage larvae. In three other dogs, microfilaremia suddenly ceased after 4 to 7 months. In these three dogs, antimicrofilarial antibodies were detectable by IFA-mf test as soon as microfilaremia ended. In the remaining two dogs, which exhibited spontaneous occult dirofilariasis, antibodies were detected at the end of the prepatent period of 6 months. The presence of adult worms was confirmed by angiocardiography. Significant IFA=mf titers (greater than or equal to 1:8) persisted after successful treatment with an adulticide. Reinfection of treated dogs reestablished occult dirofilarasis. Eosinophilia was present in all dogs and peaked at about 3, 6, and 9 months after they were inoculated with infective-stage larvae. At necropsy, the ten dogs harbored gravid, reproducing adult worms in the heart and pulmonary arteries.

Animals↗
PubMed1978

Prevalence of metazoan parasite infections in five species of Asian macaques.

Necropsy examination was performed on a total of 697 wild-caught macaques of five species. Helminthic parasites were found to be prevalent among these macaques, with species of Strongyloides, Oesophagostomum, Anatrichosoma, Trichostrongylus, and Gongylonema being the most common patent infections. Some of the larval stages of nematodes (ascarids, spirurids), cestodes (hydatid, Sparganum), and pentastomids grew into adults in appropriate definitive hosts upon experimental feeding, enabling species identification.

Animals↗
PubMed1978

Cuticular morphology of five species of Dirofilaria: a scanning electron microscope study.

Cuticular markings of five species of Dirofilaria were examined by SEM. Variations in the patterns on the en face view were observed among the species. Transverse striations were observed on the cuticles of all five species, but longitudinal ridges were lacking on Dirofilaria immitis, the type species of the subgenus Dirofilaria. They were present on the other four species, Dirofilaria repens, Dirofilaria tenuis, Dirofilaria corynodes, and Dirofilaria magnilarvatum, members of the subgenus Nochtiella. Longitudinal ridges and other cuticular structures and patterns were seen to vary among the species and with the portion and aspect of the worm examined. It is suggested that SEM would be a good tool for a detailed study of specific cuticular morphology of all species of Dirofilaria, thus contributing toward their differentiation and recognition.

Animals↗
PubMed1977

Experimental Brugia malayi infections in the rhesus monkey.

Twenty-eight rhesus monkeys in 3 groups were exposed to single (Group I), double (Group II), and multiple (Group III) inoculations with B. malayi infective larvae. Infections were monitored by microfilarial and blood counts, selected biochemical tests, IFA responses, and records of body temperature and lymphadenopathy before and/or after treatment with DEC. As a whole, the highest microfilaraemia levels were observed in Group II and lowest in Group III monkeys. Eosinophilia was a common occurrence but reached the highest mean levels in Group III. Intermittent fevers and lymph node enlargements were observed in all groups of monkeys and the occurrence of these appeared to be correlated. No definite pattern of antibody production was discernable among groups, but an inverse relationship existed between microfilaraemia and detectable microfilarial antibodies. Treatment with DEC produced a microfilaraemia-taxic effect within the initial half hour and responses to treatment varied according to individuals. Although post-treatment reinfection appeared to cause lymphoid responses and tissue eosinophilia, no substantial resistance to reinfection was observed.

Aedes↗
PubMed1976

Experimental dirofilariasis in macaques. II. Susceptibility and host responses to Dirofilaria repens of dogs and cats.

In this second series of studies on dirofilariasis in primates, 13 macaques were inoculated with infective larvae of Dirofilaria repens and were killed 2 weeks to 11 months postinoculation. Two of these animals were treated with prednisolone (as an immunosuppressant) daily beginning at 2 months of infection. Larvae and adult worms were recovered from 10 monkeys, but microfilaremia was not observed in the untreated monkeys despite the presence of gravid female worms. Eosinophilia and filarial antibodies were notable in monkeys harboring gravid worms, especially at 2, 4.5, and 6 months, probably corresponding to the period of final molt, mating, and microfilarial production, respectively. Microfilaremia appeared in the two prednisolene-treated monkeys at 5.5 and 6 months of infections, respectively, suggesting that under similar conditions infection with D. repens could produca a microfilaremia in man.

Animals↗
PubMed1976

Experimental dirofilariasis in macaques. III. Susceptibility and host responses to Dirofilaria tenuis of raccoons.

In this third of a series of studies on experimental dirofilariasis in primate hosts, 3 Macaca cynomolgus, 6 M. speciosa, and 2 M. mulatta were inoculated with infective larvae of Dirofilaria tenuis, a parasite of the raccoon, and were killed at periods ranging from 2 weeks to 13 months of infection. One M. mulatta and one M. speciosa were treated daily with prednisolone beginning 2 months after inoculation; worms were recovered from these and 5 other monkeys (7 of 11). Microfilaremia was detected during the 28th week of infection in a monkey under prednisolone treatment. Microfilaremia was found to be aperiodic in that monkey and in a raccoon. Eosinophilia and antibodies to the microfilaria reached appreciable levels in three monkeys harboring gravid worms. Development of D. tenuis in M. speciosa appeared to be comparable to that observed in man.

Animals↗
PubMed1975

Experimental infections with pathogenic free-living amebae in laboratory primate hosts: I. (B) A study on susceptibility to Acanthamoeba culbertsoni.

Susceptibility to A. culbertsoni was studied in 15 Old World monkeys by intranasal, intravenous, or intrathecal inoculation of trophozoites. No clinically detectable disease resulted from either intranasal or intravenous inoculation, but 4 of 7 monkeys inoculated intrathecally succumbed to acutely fatal meningoencephalitis. Virulence of the ameba varied with cultural age of the inoculum. Size of inoculum, passages through animal tissues, and host-immune competence were other factors of consideration in pathogenicity of the ameba.

Amebiasis↗
PubMed1975

Experimental infections with pathogenic free-living amebae in laboratory primate hosts: I (A) A study on susceptibility to Naegleria fowleri.

Studies were conducted on 27 Old World monkeys to determine their susceptibility to pathogenic strains (HB-1 and C-66) of Naegleria fowleri by intranasal, intravenous, or intrathecal inoculation of trophozoites. No clinically detectable disease resulted from either intranasal or intravenous inoculation, but 11 of 18 monkeys inoculated intrathecally succumed to acutely fatal meningoencephalitis, while the other 7 survived with no obvious permanent brain damage. Pathogenicity of N. fowleri appeared to be influenced by the strain virulence, growth phase, and cultural condition of the amebae, as well as age, immune competence, and other as yet unknown host factors.

Administration, Intranasal↗