New perspectives on a subclinical form of visceral leishmaniasis

During an epidemiological study of visceral leishmaniasis in an endemic region of Brazil, new perspectives emerged on a subclinical form of the disease. A group of 86 children with antibody to Leishmania were identified. None of these children had a history of leishmaniasis. The children were segregated into four groups: One group remained asymptomatic (n = 20), whereas another developed classic kala-azar within weeks of the index serology (n = 15). The remaining 51 patients initially had subclinical disease; 13 (25%) of these patients progressed to classic kala-azar (mean, five months). The others (75%) resolved their illness after a prolonged period (mean, 35 months). The initial illness in the subclinical group was characterized by hepatomegaly, frequent splenomegaly, intermittent cough, diarrhea, and low-grade fever. Malaise and poor weight gain were common. Giemsa-stained smears and cultures of bone marrow aspirates were usually negative for Leishmania in the absence of symptoms of classic kala-azar.

Spleen and lymph node cell populations, in vitro cell proliferation and interferon-gamma production during the primary immune response to Toxoplasma gondii

An animal model for the study of transient lymphadenopathy-splenomegaly during toxoplasmosis is presented. Injection of CBA/J mice with the low virulent, cyst-forming strain of Toxoplasma gondii (Pe strain) induces a three to four fold increase in weight and cellularity of spleen and lymph nodes with peak changes at 30-50 days after infection. The spleen displays marked haemopoiesis, a 30 fold increase in mononuclear phagocytes, and a two fold increase in Lyt2+ lymphocytes. Lymph nodes show a five fold increase in mononuclear phagocytes and a four and a half fold increase in Lyt2+ T cells. The increase in mononuclear phagocytes significantly alters T cell/macrophage ratios and this is associated with decreases in in vitro cell proliferation to mitogen and toxoplasma antigen. The relationship between alterations in cell balance of mononuclear phagocytes and T cell subsets and the expression of transient immune dysfunction can now be examined by modulating changes in these cell types.

A prospective study of visceral leishmaniasis in an endemic area of Brazil

The epidemiology, clinical patterns, and risk factors for visceral leishmaniasis were prospectively studied in an endemic area of Brazil. The prevalence of disease was 3.1% for children less than 15 years of age, and the annual incidence was 4.3 cases per 1,000 children. The number of children with disease fluctuated yearly and seasonally, and distribution of the disease varied within the endemic area. Risk factors included young age (median, three years) and malnutrition before the onset of disease. Intestinal parasitism, recent migration into the area, and house location within the area did not influence the progression of infection to disease. Serological testing indicated that 7.5% of children were infected with Leishmania each year and that the ratio of disease to infection was 1:18.5 for the whole area and 1:6.5 for the section with the highest prevalence of disease. Early diagnosis and therapy altered clinical patterns of the disease.

Leishmania donovani: an opportunistic microbe associated with progressive disease in three immunocompromised patients

Three cases are described showing that Leishmania donovani can cause progressive disease in immunocompromised hosts. The first patient was receiving corticosteroid therapy for ulcerative colitis and the second corticosteroids and cyclophosphamide for proliferative glomerulonephritis; in the third patient, leishmaniasis occurred after a long episode of hepatosplenic schistosomiasis and salmonella bacteraemia which was treated with chloramphenicol. In two cases, the patients had moved away from areas of L donovani transmission many years before the progressive disease occurred, consistent with long-term survival of the organism in normal hosts. L donovani should be added to the growing list of opportunistic microbial infections.

Association of symptomatic human infection with Toxoplasma gondii with imbalance of monocytes and antigen-specific T cell subsets

During recent symptomatic toxoplasmosis, alterations in quantity and function of mononuclear cells in peripheral blood were observed. Flow cytofluorometric analysis and differential leukocyte counts revealed increased absolute numbers of T8+ cells, Leu 7+ (natural killer/killer) cells, and monocytes. T4+ cells and HLA-DR+ cells were not significantly changed. T4/T8 cell ratios were reversed in symptomatic toxoplasmosis (0.7 +/- 0.3) and normal in chronic infection (1.7 +/- 0.5). Toxoplasma antigen induced higher numbers of T8+ and TQ1+ cells in four T cell lines from two individuals with symptomatic infection than in five T cell lines from three individuals with asymptomatic infection. Eight cloned T cell lines produced gamma interferon in an antigen-specific fashion and in higher amounts when they originated from an asymptomatic subject than from a symptomatic subject. These results indicate that marked alterations in properties of immunoregulatory cells are characteristic of recent symptomatic toxoplasmosis. The transient immune dysfunction may be a major part of the observed disease and/or a feature of successful parasitism.

Evaluation of the micro enzyme-linked immunosorbent assay (ELISA) for antibodies in American visceral leishmaniasis: antigen selection for detection of infection-specific responses

This study was designed to evaluate the ELISA for diagnosis of American visceral leishmaniasis (AVL) using antigen prepared from different Leishmania isolates and from a strain of Trypanosoma cruzi. Two Leishmania donovani chagasi isolates from Bahia and Maranhão (both states of northern Brazil), one L. donovani from Sudan, one L. mexicana amazonensis isolate, and one T. cruzi isolate were used. A total of 375 sera were tested, including 119 from AVL patients, 96 from nonleishmaniasis hospitalized patients, 20 from healthy persons, 30 from patients with mucocutaneous leishmaniasis, 28 from patients with Chagas' disease, 20 from patients with tuberculosis, 21 from leprosy patients, 27 from schistosomiasis patients and 14 from patients with systemic mycoses. The antigens prepared from L. d. chagasi (Bahia) and L. m. amazonensis showed the highest sensitivity (98% and 99%, respectively) for detecting antibodies in sera from AVL patients. However, the specificity of L. d. chagasi (Bahia) antigen was better than that of L. m. amazonensis (96% vs. 86%). Comparison among the three L. donovani isolates demonstrated that the antigen prepared with the isolate from the same area where the sera originated yielded higher mean absorbance than the others. By using spectrophotometric absorbance values it was possible to use a single dilution of serum (between 1/100-1/400) since a clear separation was seen between AVL patients and controls. No patients with the other diseases who were tested gave positive results. We suggest that ELISA can be a very convenient, sensitive, and specific test for diagnosis of AVL when soluble antigen, preferably from an isolate from the test area, is used.

Selection of a skin test antigen for American visceral leishmaniasis

Studies were designed to examine skin test responses to leishmanial antigens in American visceral leishmaniasis (AVL) in Brazil. We found that after recovery from AVL, patients had positive delayed hypersensitivity reactions to Leishmania. Different amounts of a soluble extract obtained from Leishmania donovani chagasi promastigotes were compared with whole L. d. chagasi promastigotes in persons with past AVL. The most effective soluble preparations tested contained 25 and 50 micrograms leishmanial protein. These produced positive responses in 95%-100% of the individuals with past AVL. The 25 micrograms protein dose was used in further studies. This preparation produced no positive responses in either normal controls, tuberculosis patients, or schistosomiasis patients, and less than 5% positive responses in persons with Chagas' disease. The same amount of soluble extract prepared from L. mexicana amazonensis produced 82% positive skin test responses in persons with past AVL. When persons living in an area endemic for AVL were skin tested with the 25 micrograms preparation of L. d. chagasi extract, 34.1% yielded positive tests with a low number of positive responses in young children and 48% positive in adults. Only 3.1% of the population studied had a history of AVL. We have found that positive delayed hypersensitivity response to a soluble Leishmania extract is a sensitive and specific indicator of previous infection with AVL.

In vitro cultivation of Toxoplasma gondii cysts in astrocytes in the presence of gamma interferon

Long-term culturing of Toxoplasma gondii cysts was accomplished in vitro in association with murine astrocytes and intermittent additions of gamma interferon to the media. Phase-contrast microscopy was used to follow the stages of cyst development, and electron microscopy confirmed the presence of morphologic characteristics of T. gondii cysts. T. gondii cysts formed in vitro had a single trilaminar membrane during both intracellular and extracellular existence and contained amorphous electron-dense material either throughout the cyst or in a uniform layer under the trilaminar membrane. The bradyzoites were similar to previous descriptions of tachyzoites in vitro except that they were smaller and contained numerous electron-lucent vacuoles. Gamma interferon is not necessary for cyst formation, but it controls the division of tachyzoites and may allow cysts to remain for prolonged periods without rupturing. In vitro-cultivated T. gondii cysts will be useful for producing bradyzoite and cyst antigens and for measuring the effects of antimicrobial agents and immune modulators on the viability of intracystic T. gondii.

Absence of gamma interferon and interleukin 2 production during active visceral leishmaniasis

The lymphocytes from eight patients with active visceral leishmaniasis (VL), a disease associated with marked immunologic dysfunction, were examined for ability to produce interleukin 2 (IL-2) and gamma interferon during in vitro cultivation. It was found that both IL-2 and gamma interferon production, in response to leishmania antigen, was absent during the active disease, but was restored after successful chemotherapy. Untreated VL patients produced IL-2 and gamma interferon when stimulated with phytohemagglutinin (PHA). Six patients with either active cutaneous or mucosal leishmaniasis, a disease not associated with immunosuppression, showed high levels of gamma interferon in response to leishmania antigen and PHA. Since IL-2 and gamma interferon have been shown to have important roles in the immune response and in the killing of leishmania, their absence may represent a key defect in the immune response in VL.

Immune responses to T-dependent and T-independent antigens during visceral leishmaniasis in mice: evidence for altered T-cell regulation of immune responses to non-parasite antigens

Antibody responses to T-dependent and T-"independent" antigens were studied in disease-susceptible (BALB/c and C57BL/10) and disease-resistant (A/J) mice infected with Leishmania donovani chagasi. Disease-susceptible mice but not disease-resistant mice showed a transient decrease in PFC responses to TNP on a T-dependent carrier (BGG) during the period of 4-8 weeks after infection. Infected disease-susceptible animals also showed increased responses to TNP on a type II T-independent carrier (Ficoll), which persisted until at least 14 weeks after infection. The increased responses were associated with a significant increase in anti-TNP antibody of the IgG2b subclass. When T-enriched spleen cells from infected mice and B-enriched spleen cells from uninfected mice were transferred to irradiated recipients immunized with TNP-Ficoll, increased anti-TNP PFC were observed over numbers seen in irradiated recipients which received both B and T cells from uninfected mice. Increased responses to TNP-Ficoll were also induced by prior administration of soluble leishmania extract in CFA. Infected mice immunized with TNP-LPS, a T-independent type I antigen, also had increased anti-TNP antibody responses, but had normal anti-LPS antibody responses. The elevated antibody production which occurred in response to the T-"independent" antigens could not be attributed to the relatively low polyclonal response which occurred in both disease-resistant and disease-susceptible mice infected with L. donovani chagasi. The observations are consistent with leishmania induced, transient alterations in some T-cell functions including response to haptens on T-dependent carriers, and a lack of down regulation of T-"independent" responses. Subtle lesions in immunoregulation may be important correlates of successful protozoal infection and may be responsible for some of the immunologic manifestations of the disease.

vic-Iodo Thiocyanates and Iodo Isothiocyanates. IX. A Synthesis of Penam and Other Polycyclic Β-Lactams

Penam (4-thia-1-azabicyclo[3.2.0]heptan-7-one) and 2,3-disubstituted penams are prepared conveniently from vic-iodo isothiocyanates beginning with the facile cyclization of the latter with di -t-butyl sodiomalonates. Treatment of the resulting di -t-butyl 2-(thiazolidin-2- ylene ) malonates with trifluoroacetic acid gives t-butyl 2-thiazolin-2- ylacetate derivatives which are reduced to the corresponding thiazolidines with aluminium amalgam. Cleavage of these t-butyl esters with hydrogen chloride affords β-amino acid hydrochlorides, which are cyclized to penam and its derivatives with 1-[3-( dimethylamino ) propyl ]- 3-ethylcarbodiimide hydrochloride. The structures of the (2α,3aβ,7aβ)- thiazolidine (5) and of the tricyclic β- lactam (41) have been confirmed by X-ray crystallography.

Chemistry of the Podocarpaceae. LXIX. Further Lignans from te Wood of Dacrydium intermedium

Structures and absolute configurations are established for five new lignans isolated from the wood of the New Zealand podocarp Dacrydium intermedium Kirk. X-ray crystallography has been used to confirm the structure of one of the new lignans. Structures for two further inseparable lignans are provisionally assigned. The structure of one of three lignans previously isolated from the wood is revised.

Leishmaniose mucocutânea humana em Três Braços, Bahia - Brasil: uma área de transmissão de Leishmania braziliensis braziliensis. III. Comprometimento mucoso e evolução inicial

Numa análise de 57 pacientes o acometimento da mucosa foi mais comumente observado em homens (77%) na terceira década de vida, embora fosse grande a variação das idades e ocorrendo mesmo o acometimento de duas crianças. Com a exceção de nove pacientes (16%) todos os outros tinham sinais de leishmaniose cutânea sendo que em somente oito (14%) de lesão era ativa. O acometimento do nariz foi observado em 100% de 19 pacientes que apresentavam lesões múltiplas e em 92% de 38 pacientes apresentando uma única lesão. A faringe, palato, laringe e lábio superior foram afetados nesta experiência. 42% dos pacientes com lesões múltiplas apresentavam acometimento da laringe sendo que em dois pacientes a única lesão existente apresentava-se neste ponto. Não foi observada qualquer diferença relacionada com a idade no que se referia à existencia de lesões únicas ou múltiplas. A duração do acometimento da mucosa variou de menos de 4 até 264 meses. Somente 7% desenvolveram o acometimento da mucosa após mais de dez anos o desenvolvimento da lesão cutânea. Os pacientes usualmente responderam ao tra-tamento adequado por antimonial embora em algumas exceções fosse usada amphotericina B. Morreram três pacientes que se recusaram a colaborar no tratamento. Dois anos após o tratamento observou-se positividade de anticorpos fluorescentes em somente 18% dos pacientes entre aqueles acompanhados.

Metal-proton interactions in benzylamine complexes of palladium(II): The effect of methyl substitution at nitrogen and the role of the interaction during cyclopalladation. X-ray crystal structure of tetrabenzylaminepalladium(II) acetate chloride

Reaction of Pd(O2CMe)2 with PhCH2NH2 leads to either Pd(NH2CH2Ph)2(O2CMe)2 or [Pd(NH2CH2Ph)4] [O2CMe]2. The X-ray crystal structure of [Pd(NH2CH2Ph)4] [Cl] [O2CMe] shows pairs of [Pd(NH2CH2Ph)4]2+ ions held together by hydrogen bonds from the NH proton to chlorine and oxygen atoms of the anions, and the absence of interactions between phenyl ring ortho protons and the metal. PhCH2NHMe reacts with Pd(O2CMe)2 giving Pd(NHMeCH2Ph)2(O2CMe) and PhCH2NMe2 gives the cyclometallate [Pd(NMe2CH2Ph-C,N)(�-O2CMe)]2. 1H N.M.R. spectra indicate that the complexes Pd(NMe2CH2Ph)(L)(O2CMe)2 (L = PhNH2, o-MeC6H4NH2) prepared from [Pd(L)(O2CMe)(�-O2CMe)]2, contain an interaction of the benzylamine ortho aromatic protons with the metal whereas Pd(NHMeCH2Ph)(L)(O2CMe)2 (L = o-MeC6H4NH2) does not. 1H n.m.r. analysis of PdCl42- and PhCH2NMe2 in (2Hl)methanol at 400 MHz indicates a 1 : 1 reaction stoichiometry and metal-proton interactions in intermediates containing above-plane and in-plane geometry of the aromatic ring, before metallation takes place. A 400-MHz spectral analysis of Pd(O2CMe), and PhCH2NMe2 in CDCl, suggests similarly orientated species arise in the reaction giving [Pd(NMe2CH2Ph-C,N)(�-O2CMe)]2.

A comparative study of different Leishmania tropica isolates from Iran: correlation between infectivity and cytochemical properties

Five isolates of Leishmania tropica from southwest Iran were studied to identify correlates among human disease, animal infectivity, and surface biochemistry. Clinical patterns of the disease in humans differed. One striking strain, LT-249, produced a small dry lesion which did not heal during four years of observation. Infectivity of these L. tropica for mice was correlated with lectin agglutination patterns and interaction with macrophages. There was also a significant difference among the five isolates regarding infectivity for BALB/c mice; isolate LT-249 was not infective whereas all the others were. All isolates agglutinated with Concanavalin A (Con A), Ricinus communis and soybean agglutinin but not with four other lectins listed. However, Leishmania isolate LT-249 showed much poorer agglutination with all lectins than did the other four isolates. Two isolates were selected for detailed study of attachment to macrophages, one, LT-249, which was not infective and one, LT-252, which was infective for BALB/c mice. The number of promastigotes which attached to macrophages in vitro was the same, but the mechanism of attachment differed since only the LT-252 bound predominantly by Con A-mannose receptor interaction. These results indicate a correlation among animal infectivity, lectin agglutination, and promastigote-macrophage attachment. In particular one isolate of L. tropica which caused prolonged infection in humans was not infective in BALB/c mice, showed poor agglutination with lectins, and bound to macrophages by a different mechanism than did other isolates from the same region.

Effect of hydrocortisone on macrophage response to lymphokine

To define the suppressive effects of corticosteroids on mononuclear phagocyte antiprotozoal activity, normal resident peritoneal macrophages were exposed to hydrocortisone (HC) before, during, and after in vitro activation with cell-free supernatants (lymphokines). The presence of pharmacological concentrations of HC before or during lymphokine activation prevented normal macrophages from acquiring the capacity to either respond oxidatively to Toxoplasma gondii ingestion or to inhibit intracellular toxoplasma replication. HC had no effect, however, on the cells fully stimulated by lymphokine or on macrophages previously activated in vivo. These findings indicate that although HC does not impair the ability of activated macrophages to control intracellular protozoan infection, it does compromise the antimicrobial activity of the cell-mediated immune system by rendering normal macrophages unresponsive to lymphokine.