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J J Shaw

Publications and source records attributed to J J Shaw.

At least 55 records · Page 3Linked to original sources
PubMed1988

Observations on the development of Leishmania (L.) chagasi Cunha and Chagas in the midgut of the sandfly vector Lutzomyia longipalpis (Lutz and Neiva).

Previous observations have shown that forms of Leishmania, infective to hamsters, are present in the midgut of experimentally infected sandflies from 15-221 hours after the infective bloodmeal. In a continuation of these studies, stained smears of the midgut contents of Lutzomyia longipalpis infected with Leishmania (L.) chagasi, made at intervals between 15-120 hours, revealed two lines of parasite development. One of these is the direct transformation of small, non-dividing amastigotes into very small promastigotes, which are considered to represent the "infective" or "metacyclic" flagellates involved in subsequent transmission of the parasite. The other stems from enlarged, highly vacuolated amastigotes which undergo at least two divisions before giving rise to large, elongate and non-dividing promastigotes. These are thought to represent the non-infective forms of the parasite seen in in vitro cultures, and their function remains speculative.

Animals↗
PubMed1987

Leishmaniasis in Brazil. XXIV. Natural flagellate infections of sandflies (Diptera: Psychodidae) in Pará State, with particular reference to the rôle of Psychodopygus wellcomei as the vector of Leishmania braziliensis braziliensis in the Serra dos Carajás.

Between July 1983 and December 1984 natural flagellate infections were found in 114 (1%) of 11,586 female phlebotomine sandflies (Diptera: Psychodidae) of 21 species. A further 1084 females of 17 other species were not infected. Identification of the organisms on a number of occasions confirms the exclusive parasite/vector relationship of Leishmania mexicana amazonensis/Lutzomyia flaviscutellata and Le. braziliensis braziliensis/Psychodopygus "wellcomei". Undescribed or unidentified Leishmania spp. were isolated from Lu. shawi, Lu. ubiquitalis, Lu. whitmani, Ps. hirsutus, Ps. paraensis Ps. "wellcomei", and trypanosomes from Lu. nordestina and Lu. trinidadensis. Flagellate infections were recorded in 8 of 21 species examined for the first time, and some were isolated directly from insects into cultures. Le. b. braziliensis was transmitted to a hamster by the bite of a wild-caught, naturally infected Ps. "wellcomei". 7 of the 35 infected Ps. "wellcomei" were allowed to oviposit and the eggs were reared to adults. Four produced Ps. wellcomei males only, confirming the rôle of this species as the major vector of Le. b. braziliensis.

Animals↗
PubMed1987

Leishmaniasis in Brazil: XXIII. The identification of Leishmania braziliensis braziliensis in wild-caught neotropical sandflies using monoclonal antibodies.

Using the indirect immunofluorescence test natural flagellate infections of wild-caught sandflies, from the Serra dos Carajás region of Pará State, Brazil, were identified by sequentially staining smears made from the infected flies with monoclonal antibodies. With normal methods of isolation 30% of the infections were identifiable, but when monoclonal antibodies specific to Leishmania braziliensis braziliensis were used a further 26% were identified. The staining of organisms in smears of natural infections was different from that seen with culture forms and with forms from experimentally infected wild flies. A monoclonal antibody previously thought to be specific for Leishmania did not react with culture forms of Endotrypanum, but did react with those of monoxenous insect parasites.

Animals↗
PubMed1987

Leishmaniasis in Brazil. XXV. Sandfly vectors of Leishmania in Pará State, Brazil.

Leishmania of the braziliensis complex were isolated from various members of the squamiventris series sandflies, including Psychodopygus chagasi (Costa Lima), P.s.maripaensis (Ready et al.), P.s.squamiventris (Lutz & Neiva), and also P.ayrozai (Barreto & Coutinho) and Lutzomyia umbratilis Ward & Fraiha. Three different serodemes of Le.b.guyanensis Floch were isolated from Lu.anduzei Rozeboom, Lu.umbratilis and Lu.whitmani Antunes & Coutinho, simultaneously captured in the same area. Unidentified Leishmania were isolated from P.claustrei Abonnenc et al., and trypanosomes from Lu.pinottii Damasceno & Arouck and an unidentified species of Lutzomyia. A naturally infected female P.s.maripaensis transmitted a braziliensis complex Leishmania, by bite, to a hamster.

Animals↗
PubMed1987

Regulation of the vir genes of Agrobacterium tumefaciens plasmid pTiC58.

The virulence (vir) region of pTiC58 was screened for promoter activities by using gene fusions to a promoterless lux operon in the broad-host-range vector pUCD615. Active vir fragments contained the strongly acetosyringone-inducible promoters of virB, virC, virD, and virE and the weakly inducible promoters of virA and virG. Identical induction patterns were obtained with freshly sliced carrot disks, suggesting that an inducer is released after plant tissue is wounded. Optimal conditions for vir gene induction were pH 5.7 for 50 microM acetosyringone or sinapic acid. The induction of virB and virE by acetosyringone was strictly dependent on intact virA and virG loci. An increase in the copy number of virG resulted in a proportional, acetosyringone-independent increase in vir gene expression, and a further increase occurred only if an inducing compound and virA were present.

Conjugation, Genetic↗
PubMed1986

Apgar scores and asphyxia. Results of a study and proposal for a clinical grading system.

The Apgar score (AS) was devised in 1953 as a simple system for classifying neonatal condition at 1 minute and was later modified to include status at 5 minutes. However, studies have documented pitfalls, e.g. a poor correlation between AS and acid-base status. We studied 35 infants born at term. ASs were assigned by two nurses not involved in the delivery, and antepartum and postpartum events were noted. We confirmed the following: (i) labour ward staff tend to overestimate ASs; (ii) there is a poor correlation between the AS and acid-base status; and (iii) the labour ward staff's decision to resuscitate with intermittent positive-pressure respiration (IPPR) correlates with the AS but not with blood gas status. Infants with initially low ASs and/or a brief requirement for IPPR may be recorded by medical or nursing staff as being asphyxiated at birth. Our results show that low ASs may be associated with normal acid-base status and vice versa. In order further to define asphyxia, we therefore propose that a grading system which incorporates clinical data and the AS be used. Use of such a system would facilitate inter-area comparisons of grades of asphyxia encountered, efficacy of intervention programmes and developmental outcome of asphyxiated neonates.

Apgar Score↗
PubMed1986

Leishmaniasis in Brazil. XXII: Characterization of Leishmania from man, dogs and the sandfly Lutzomyia longipalpis (Lutz & Neiva, 1912) isolated during an outbreak of visceral leishmaniasis in Santarém, Pará State.

During epidemiological studies on an outbreak of visceral leishmaniasis in Santarém, Pará State, north Brazil, isolates of Leishmania from two children, three dogs and six naturally infected specimens of the sandfly Lutzomyia longipalpis were compared, biochemically, by starch-gel enzyme electrophoresis. They have proved to be indistinguishable from each other, and from a reference strain of Leishmania chagasi Cunha & Chagas, 1937 from a case of human visceral leishmaniasis from Bahia State, north-east Brazil, on their enzyme profiles for ASAT, ALAT, PGM, GPI, MDH and MPI. Lu. longipalpis is the principal, and possibly the only vector to man in the Amazon Region of Brazil.

Animals↗
PubMed1986

Separation of female Psychodopygus wellcomei and P. complexus (Diptera: Psychodidae) by cuticular hydrocarbon analysis.

Psychodopygus wellcomei (Diptera: Psychodidae), vector of Leishmania braziliensis braziliensis - causative agent of cutaneous leishmaniasis in Brazil, cannot be distinguished from sympatric P. complexus either by morphometrics or isoenzyme profiles. We report here the use of cuticular hydrocarbon analysis in the successful separation of individual female P. wellcomei and P. complexus. This technique involves the use of gas liquid chromatography and discriminant function analysis.

Animals↗
PubMed1986

Chemical analysis of compounds extracted from the tergal "spots" of Lutzomyia longipalpis from Brazil.

The chemical composition of the compounds contained in the tergal spots of Lutzomyia longipalpis was investigated. Four populations of L. longipalpis were examined, originating from: Sobral, Ceará, Brazil (one spot and two spot populations), Santarém, Pará, Brazil (one spot) and Marajó Island, Pará, Brazil (one spot). The tergal spots were dissected out, extracted in hexane and analysed on a gas chromatograph/mass spectrometer. Two compounds were found, identical to compounds found in earlier studies, but there was no correlation between number of tergal spots and type of compound present. It was suggested that the number of tergal spots could not be used as a marker for reproductively isolated populations, and that analysis of the compound present within the spots might be necessary to characterize potentially good vector populations.

Animals↗
PubMed1985

Leishmaniasis in Brazil. XXI. Visceral leishmaniasis in the Amazon Region and further observations on the role of Lutzomyia longipalpis (Lutz & Neiva, 1912) as the vector.

Further evidence is presented incriminating the sandfly Lutzomyia longipalpis as the vector of Leishmania chagasi, the causative agent of American visceral leishmaniasis, in the Amazon Region of Brazil. During an outbreak of the disease in Santarém, Pará State, this insect was shown to be the only species of sandfly consistently present in and around the patient's homes, where it often occurred in very large numbers. Of 491 specimens dissected, 35 (7.14%) proved to be infected, and isolates of L. chagasi were made from 16 of 27 of these sandflies following the inoculation of the promastigotes into hamsters. Finally, the parasite was transmitted to four other hamsters which had been subjected to the bites of large numbers of wild-caught Lu. longipalpis. Isolates of Leishmania from Lu. longipalpis captures in Santarém, and in another focus of visceral leishmaniasis on the Island of Marajó, Pará, have been shown to be biologically and biochemically indistinguishable from the parasite infecting man, dogs and foxes in Pará, and from stocks obtained from man elsewhere in Brazil (Bahia and Ceará States).

Animals↗
PubMed1983

Leishmaniasis in Brazil. XIX: visceral leishmaniasis in the Amazon Region, and the presence of Lutzomyia longipalpis on the Island of Marajó, Pará State.

Sporadic cases of visceral leishmaniasis in Amazonian Brazil appear limited to Pará State, in the lower Amazon valley and principally near the Atlantic coast. The fox Cerdocyon thous (L.) has been incriminated as a natural host of the causative parasite, Leishmania donovani chagasi, but past doubts have existed over the identification of the most likely vector as Lutzomyia (Lutzomyia) longipalpis (Lutz & Neiva, 1912). Investigations on two of five recent cases of visceral leishmaniasis of man in the Districts of Cachoeira do Arari and Salvaterra, on the eastern part of the Island of Marajó, Pará showed undoubted Lu. longipalpis to be abundant in one house and in numerous chicken-houses. This is the first record of Lu. longipalpis on Marajó Island, and the finding supports previous implication of this sandfly in the epidemiology of visceral leishmaniasis in other parts of Pará. Morphological differences have been noted between this insect from Marajó and other specimens from more highly endemic regions in the States of Ceará and Minas Gerais, Brazil.

Adult↗