Update on the biology of Triatoma dimidiata Latreille (Hemiptera: Reduviidae) under laboratory conditions.

Feeding time, postfeeding defecation delay, and life cycle for each stage of a cohort of recently colonized Mexican Triatoma dimidiata were evaluated, and results were compared to existing published information on this species. Seventy-five nymphs (41.7%) completed a cycle with an average time from N-I to adult of 142 +/- 64 days. The average span in days for each stage was 20.2 for N-I, 17.9 for N-II, 10.1 for N-III, 43.6 for N-IV, and 55.1 for N-V. First-stage nymphs had the highest mean feeding time (25 min) and the longest postfeeding defecation delay (45 min). Differences among biological data from previous studies and the present study confirm the importance of conducting research on the behavior of the indigenous triatomine species from various countries.

Amiloidosis secundaria: características clínicas / Clinical characteristic: secundary amyloidosis

Objetivo: determinar las características clínicas de la amiloidosis secundaria. Material y métodos: Se realizó un estudio retrospectivo de 115 pacientes con diagnóstico histopatológico de amiloidosis secundaria entre 1964 y 1997, determinados por biopsia renal (97.5 por ciento) o de glándula salival menor (2.5 por ciento). Resultados: como enfermedades determinantes se encontraron TBC pulmonar (90.43 por ciento), bronquiectasias (6.08 por ciento), osteomielitis (1.74 por ciento). Las manifestaciones clínicas fueron: edema en 98.2 por ciento, proteinuria 100 por ciento, e hipotensión en 30.43 por ciento. La proteinuria en 24 horas fluctuó entre 1.26 y 3.23 gr. El rango en que fluctuó la albúmina sérica fue de 0.6 a 3 gr/dl. Se encontró función renal normal en 5 por ciento e insuficiencia renal en 95 por ciento de los pacientes

Human tumor models in the severe combined immune deficient (scid) mouse.

PURPOSE: To test a number of established human tumor cell lines and early passage breast cancer (UACC2150) and melanoma cells (UACC1273) for growth in the scid mouse and the tumors' response to conventional chemotherapeutic drugs. METHODS: Established melanoma (A375, C81-61), colon (SW480), lung (A549), lymphomoblastoid leukemia (LCL-B), promyelocytic leukemia (HL60), prostate (PC-3, DU145), and breast (MCF7) cell lines were injected at subcutaneous (s.c.), intraperitoneal (i.p.), or mammary fat pad (MFP) sites. Tumor volume growth curves and survival curves were established for the various tumor cell lines. Carmustine (BCNU), cisplatin (CDDP), cyclophosphamide (CPA), doxorubicin, dacarbazine (DTIC), tamoxifen and vincristine were injected s.c. or i.p.. The chemotherapeutic drug effects on tumor volumes and survival were determined. RESULTS: Tumor growth occurred with each cell type. After i.p. injection, 90% mortality occurred within 26 to 60 days except for the early passage melanoma cell line UACC1273 with which mortality occurred within approximately 90 days. In the MCF7 breast model, treatment with tamoxifen (P < 0.001) and CPA (P < 0.0001) resulted in significant tumor growth delay compared with control groups. BCNU and CDDP resulted in significant tumor growth delays relative to control in SW480 colon cancer (P < 0.0014) and A375 melanoma (P < 0.0001) models, respectively. CPA and doxorubicin improved survival in the HL60 leukemia model (P = 0.0018). CONCLUSIONS: These scid mouse human tumor models appear to reflect the clinical situation in that clinically active chemotherapeutic drugs are similarly active in the scid mouse models. Therefore, the scid mouse models may be useful for testing new chemotherapeutic agents against various human cancer types.

Effects of amifostine and paclitaxel on growth of human ovarian carcinoma xenografts in the severe combined immune-deficient mouse: preliminary results.

The effects of amifostine on paclitaxel-induced tumor growth delay using in vivo human ovarian cancer models were evaluated. In some mouse strains amifostine causes hypothermia and/or vasodilation, leading to increased spleen weight and ascites that can result in experimental artifacts. We found, however, that amifostine alone at 100 or 200 mg/kg intraperitoneally did not substantially alter body weight, spleen weight, or body temperature in severe combined immune-deficient (scid) mice bearing human 2780 ovarian cancer cells. In a model of minimal tumor burden (tumor cells injected subcutaneously day 0, drug treatment started day 1) scid mice receiving paclitaxel (27 mg/kg intraperitoneally) with or without amifostine had increased survival at day 76 (83% to 100%) compared with mice that did not receive paclitaxel (17% to 33%). For a model of advanced ovarian cancer, mice received tumor cell injections on day 0 and did not begin drug treatment until tumors were palpable (0.2 x 0.2 cm). Paclitaxel given for five repetitive doses significantly decreased tumor growth (P = .0001) in the advanced ovarian cancer model, and these results were the same whether or not mice received amifostine prior to each paclitaxel dose. We conclude that the scid mouse is a good model for evaluating amifostine in vivo, and that there was no evidence of amifostine-induced tumor protection in these scid mouse human ovarian cancer models. In future studies we will evaluate whether the cytoprotective effects of amifostine will allow dose escalation of paclitaxel and result in enhanced antitumor effects.

[The focal control of malaria. Focal treatment using chemoprophylaxis and home insecticide spraying for the control of malaria in southern Mexico]. / Control focal del paludismo. Tratamiento focal usando quimioprofilaxis y rociado intradomiciliar con insecticida para el control del paludismo en el sur de México.

The efficacy of a focal control strategy for malaria was evaluated against a conventional scheme carried out in two groups of villages in the Soconusco, southern Chiapas, Mexico. Focal control consisted on the prophylactic administration of antimalarial drugs to people who had experienced malaria episodes two years previous to the study. Homes of these malaria patients were also sprayed indoors with DDT. The traditional strategy consisted on the treatment of all patients with antimalarial drugs as well as indoor spraying with DDT of all houses in the villages. Results from the focal control demonstrated similar efficacy as compared to conventional. However, in terms of cost, focal control was four fold more economical. Focal control had an additional advantage of incorporating community participation within the control operations.

Long-term engraftment of fresh human myeloma cells in SCID mice.

Using highly purified myeloma cells from patient bone marrow, we established human-murine myeloma chimeras in severe combined immunodeficiency (SCID) mice and documented secretion of monoclonal human immunoglobulins (Hulgs) in the mice for up to 299 days. Monoclonality of circulating Hulgs was found only when highly purified myeloma cells were injected intraperitoneally. In contrast, injection of unfractionated myeloma marrow led to the development of polyclonal Hulgs in the SCID mice. The criteria for myeloma engraftment included prolonged presence of monoclonal Hulgs in the sera of SCID mice and/or detection of human myeloma cells in their tissues by immunohistochemical examination. Ninety-one percent (10/11) of the fresh purified myeloma specimens engrafted in the SCID mice. Fifty-five percent (6/11) of the patient samples resulted in human B-cell grafts, and 45% (5/11) were identifiable as human myeloma chimeras. Pathologic studies showed that most human plasmacytes were located in the peritoneal cavity but metastatic infiltrates were also found in other organs in 69% of the SCID-human myeloma chimeras. This chimeric model should provide a useful tool for characterization of growth modulation and microenvironmental interactions as well as a means of testing new therapeutic approaches to multiple myeloma.

Growth and dissemination of human malignant melanoma cells in mice with severe combined immune deficiency.

BACKGROUND: The severe combined immune deficiency (SCID) mouse is lacking mature B and T lymphocytes and may be permissive for human tumor growth and metastasis. EXPERIMENTAL DESIGN: SCID mice received human melanoma cells of diverse origins including: 2 established cell lines, 4 early passage cell lines, and fresh or cryopreserved cells obtained directly from 9 patient biopsies. They were introduced into SCID mice via intraperitoneal, subcutaneous and intravenous injections. RESULTS: Tumor growth occurred with each of the 15 melanoma specimens for a take rate of 100% considering cell source. In addition, 60% of the 102 total mice injected displayed tumor growth in at least one site. The most consistent tumor growth (77%) occurred after intraperitoneal injection. Tumors developed in 41 and 48% of mice injected subcutaneously and intravenously, respectively. The mice developed both local tumor growth with palpable tumor nodules at injection sites and hematogenous and/or lymphatic dissemination to multiple sites in the abdominal and thoracic cavities. The number of metastases per animal averaged 16.3 and the number per organ ranged from 1 to 38. Melanotic and amelanotic tumor nodules obtained from a single patient retained their original characteristics with regard to melanin production after passage in the SCID mouse. The appearance of the human melanoma cells in SCID mouse tissues ranged from implants on the organ capsule to frank parenchymal organ involvement and vascular invasion. Some small foci of tumor were only detected using immunohistochemistry with monoclonal antibodies against the S-100 and HMB-45 to melanoma-related antigens. CONCLUSIONS: We conclude that the SCID mouse consistently supports growth, invasion, and metastatic spread of human melanoma cells, including specimens obtained from fresh patient biopsies. The SCID mouse will serve as a relevant in vivo model for studying the biology of human malignant melanoma and screening new therapeutic agents.

[Intra-domiciliary low volume spraying of malathion and deltamethrin for controlling Anopheles sp]. / Aplicación intradomiciliar de malatión y deltametrina en bajo volumen para el control de Anopheles sp.

The effectiveness of low volume (LV) house-spraying of deltamethrin 0.027 per cent and malathion 20 per cent in the control of Anopheles sp was evaluated in two villages of Tabasco, México during the last semester of 1987. Two spray rounds were carried out at three-month intervals, using Fontan R-12 back-pack-space sprayers. Residual effect and cost-benefit were evaluated and compared to the standard DDT spraying technique using the Hudson X-pert sprayer. The entomological evaluation focused on mortality rates and density levels observed from intra and peridomicilliary man biting collections, indoor mosquito resting densities, curtain trap and the standard WHO wall bioassay. It was determined that when using the LV method these insecticides were highly effective. Malathion showed a residual effect of eight weeks whereas deltamethrin was found to have a residual activity of up to 12 weeks. Deltamethrin was more effective in reducing intra and peridomiciliary biting rates, and indoor resting mosquitoes. The cost-benefit ratio of deltamethrin and malathion LV house-spraying was 2.56 and 0.89, respectively, as compared to the standard DDT house-spraying. Considering its effectiveness in anopheline control and its cost-benefit, in addition to being a functional technique, intradomicile LV insecticide spraying should be considered as a practical alternative in malaria control programs.

A graphical derivative approach to the photometric determination of lutetium and praseodymium in mixtures.

The reaction of lanthanides with 1,4-dihydroxyanthraquinone has been examined and optimum conditions have been found for the separate spectrophotometric determination of Lu and Pr. A graphical method based on use of first and second derivative spectra has been developed for analysis of binary mixtures of the two, in concentration ratios from 1:5 to 5:1. Linear calibration curves were obtained between 1 and 10 mug/ml.

Trace zinc determination by synchronous derivative fluorimetry.

A sensitive and selective synchronous-scanning derivative spectrofluorimetric determination of zinc based on the formation of a fluorescent chelate with 2-furaldehyde 2-pyridylhydrazone (FAPH) is described, and its analytical performance compared with that of the ordinary fluorimetric method. The detection limits lie in the ng ml range and the coefficient of variation is below 2% in both cases. The methods have been applied to the trace determination of zinc in pig liver tissue and environmental fume samples.

Photometric determination of cobalt by means of photochemically generated anti-2-furaldehyde 2-pyridylhydrazone.

The photochemical syn-anti isomerization of 2-furaldehyde 2-pyridylhydrazone (FAPH) in ethanolic solutions has been investigated. A study of the infrared, visible and ultraviolet, and n.m.r. spectra of the two isomers was made. The syn-anti ratio at the photostationary state was determined. syn-FAPH scarcely reacts with metal ions but the anti-FAPH formed by irradiation gives sensitive reactions with several metal ions to form stable chelates. A photometric method for the determination of cobalt (0.025-1.0 microg/ml ) in aqueous ethanolic medium (50% v/v ) at pH 9.7 is described. A detection limit of 0.007 microg/ml and relative standard deviation of 0.5% were found. By consideration of the syn-anti ratio at the photostationary state, the stoichiometry of the chelate was determined. An application of this technique to determination of cobalt in environmental fume samples is also described.

Production of hybrids of mouse myeloma cells and protozoa which express parasite antigens.

Mouse myeloma cells were fused with blood stage forms of the rodent malaria parasite Plasmodium chabaudi and with promastigotes of Leishmania donovani, the causative agent of kala-azar in man. The fusion was carried out by polyethylene glycol treatment. The parasites provided the enzyme which enabled the hybrids to grow in selective medium containing aminopterin. Clones of parasite-myeloma hybrids grown in continuous culture for up to 5 months expressed parasite antigen and induced anti-parasite antibodies in mice.