Epidemiology of bluetongue in Central America and the Caribbean: initial entomological findings. Regional Bluetongue Team

Forty-four species of Culicoides (Diptera: Ceratopogonidae) were caught in insect light traps during the first 2 years of studies on the epidemiology of bluetongue virus in the Caribbean and Central America. Traps were operated near sentinel ruminants which were bled monthly for serologic evaluation and then virus isolation. More than 570,000 individuals were identified. Culicoides insignis Lutz accounted for 90% of the catch, C. filarifer Hoffman/C. ocumarensis Ortiz 5%, C. furens Poey 3% and C. pusillus Lutz 2%. Other species accounted for less than 1% of the total catch. Sentinel ruminants became seropositive when C. insignis populations were high at many study sites. At a few sites C. pusillus and C. filarifer/C. ocumarensis were predominant or were present in large numbers during seroconversions of sentinels. Virus isolations were obtained from sentinel ruminants during times when these same species were present in large populations.     

Benzodiazepine withdrawal reaction in two children following discontinuation of sedation with midazolam

OBJECTIVE: To report the occurrence of recurrent benzodiazepine withdrawal reactions in two very young children following discontinuation of sedation with midazolam. CASE SUMMARY: A 15-month-old boy with apneic episodes was sedated with midazolam for 12 days with constant infusion. Half a day after discontinuation of the midazolam the boy became restless, tachycardic, and hyperpyrexic. When midazolam was readministered, all symptoms disappeared. Four days later midazolam was again discontinued and within 12 hours the same signs and symptoms reappeared. Midazolam infusion was restarted, and the signs and symptoms disappeared for the second time. After thoracotomy, a 14-day-old boy received intravenous midazolam for sedation for 29 days. Within 12 hours after discontinuation of midazolam he became restless, developed a bulging stomach secondary to aerophagia, and was vomiting. Midazolam therapy was reinstituted and continued for another 2 months by constant infusion. Thereafter, the boy was successfully weaned from artificial ventilation in 5 days under sedation with midazolam. About 12 hours after discontinuation of midazolam the boy became restless, tachycardic, again developed a bulging stomach because of aerophagia, and vomited. When the child was sedated with clorazepate by continuous infusion, the signs and symptoms disappeared. DISCUSSION: Case reports describing benzodiazepine withdrawal reaction upon discontinuation of midazolam were reviewed and compared. The symptoms observed in the children we present resemble those mentioned in the three children and two adults reported previously. Unique in the very young children in this article is the occurrence of gastrointestinal symptoms, which most likely are the result of air being swallowed secondary to severe agitation. CONCLUSIONS: Midazolam withdrawal reactions in adults and children, particularly in an intensive care unit, can be significant. Considerable caution must be taken with relatively long-term administration and abrupt discontinuation of midazolam.     

Progress in the study of IL-8

In vitro cultivation of B. burgdorferi in BSK medium results in the loss of infectivity and pathogenicity after repeated passages. To prevent this loss, a feeder layer of tibio-tarsal joint tissue derived from newborn LEW/N rats was grown on Cytodex 3 microcarriers in ESG (formerly BSKE), a novel medium developed to support the growth of both the feeder layer and B. burgdorferi. A new pathogenic isolate (FNJ) and a high passage, non-pathogenic strain (TNJ) grew well in this co-culture system with high yields of viable organism. FNJ caused no growth inhibition or visible damage to the cells in the feeder layer. FNJ remained arthritogenic for newborn LEW/N rats after 22 passages in the co-culture system, but lost its arthritogenicity after 7 passages when cultured in BSK medium. This borrelia-mammalian tissue co-culture technique presents an experimental system to study the long term interactions of B. burgdorferi with the infected host tissues in vitro, as well as facilitate diagnostic tests and vaccine development.     

Treatment of colorectal cancer: hepatic metastasis

Almost one-third of patients dying from colorectal cancer have tumor limited to the liver. Systemic chemotherapy is the appropriate palliative management of patients with metastases to the liver and other sites. For many patients with isolated hepatic metastases, systemic chemotherapy is also the most appropriate treatment. However, results with systemic chemotherapy indicate that one-third or less of patients will respond to such treatments, and long-term survival is rare. In this report we provide information concerning the natural history of colorectal hepatic metastases, followed by the expected benefits with systemic chemotherapy. This information provides background for the regional therapeutic strategies of surgical resection, cryosurgery, and hepatic artery chemotherapy. We discuss the selection factors appropriate for such treatments, morbidity and mortality, and the potential long-term benefits of such approaches. The last section focuses on surgical considerations in hepatic resection and hepatic artery chemotherapy.     

Expression of platelet-derived growth factor and its receptors by two pre-B acute lymphocytic leukemia cell lines

Platelet-derived growth factors (PDGF) are potent regulators of cell proliferation. The three isoforms of PDGF AA, AB, and BB are encoded by two genes: PDGF A and PDGF B. The v-sis oncogene is homologous to the PDGF-B gene. v-sis can transform cells that express the appropriate PDGF receptors. Two different types of receptors, PDGF-alpha and PDGF-beta, also encoded by two genes, have been identified. We show that two cell lines. SMS-SB and NALM-6, both derived from pre-B-cell acute lymphocytic leukemias, express the PDGF-A chain gene, and one of them, SMS-SB, releases PDGF-A chains into the media. The SMS-SB cells also express the PDGF-beta receptor, whereas NALM-6 cells express the PDGF-alpha receptor and bind PDGF. This extends the possible targets for PDGF to the B-cell lineage lymphocytes.