Small proportions: what to report for confidence intervals?

The original article to which this Erratum refers was published in Pharmacoepidemiology and Drug Safety 2005; 14: 239–247.     

Gastric cancer mortality and nitrate levels in Wisconsin drinking water.

The association between nitrate levels in public and private sources of drinking water and gastric cancer mortality in Wisconsin was investigated in a case-control study. All gastric cancer deaths of Wisconsin residents from 1982 through 1985 were compared with deaths from other causes (controls), and nitrate levels in the home drinking water of these residents were determined. Nitrate measures for public sources were obtained from historic nitrate data from municipal sources that existed in 1970. Nitrate measures for private water sources were obtained by testing the wells individually at the existing residences. Controls were matched individually to gastric cancer cases with respect to sex, year of birth, year of death, Wisconsin birth, and Wisconsin residency at the time of death. Matched-pair analyses were performed on the paired data, and the following levels of nitrate-nitrogen exposure were used as indicators of exposure: 0.5, 2.5, 5.0, and 10.0 mg/l. Matched-pair analysis was also performed for which private water supply constituted exposure. Odds ratios and 95% confidence intervals were, respectively, 0.92 (0.75, 1.12); 0.97 (0.74, 1.35); 0.86 (0.69, 1.08); 1.50 (0.12, 18.25); and 1.09 (0.82, 1.47) for exposure to private well-water sources. These results did not indicate an increased risk of gastric cancer at any level.     

Fusion with mouse thymocytes leads to expression of p30 antigen in fibroblasts of BALB/Mo mice

Embryonic fibroblasts of BALB/Mo mice carrying the endogenous genome of Moloney murine leukemia virus (M-MuLV) in addition to murine type C viruses were fused with Swiss mouse thymocytes, B lymphocytes, macrophages, or embryonic fibroblasts. We wanted to determine whether these cells contained physiological factors involved in induction of the integrated viral genome(s). Fusion with thymocytes and, to a lesser extent, fusion with B lymphocytes induced viral genome expression as demonstrated by the appearance of viral structural protein p30 detected by immunofluorescence. Maximal expression of p30 was observed about 36 hr after the fusion event, using thymocytes from 1- to 2-week-old Swiss mice. This temporary expression of p30 was not accompanied by release of infectious virus. Fusion of BALB/Mo fibroblasts with Swiss mouse macrophages or embryonic fibroblasts led to neither the production of p30 nor the release of detectable infectious virus. These results suggest the existence of thymocyte-specific and possibly B lymphocyte-specific factor(s) involved in the control of expression of integrated viral genome(s).     

Placentally derived prostaglandin E2 acts via the EP4 receptor to inhibit IL-2-dependent proliferation of CTLL-2 T cells

A number of immunomodulatory molecules are present in the placenta, including cytokines, prostaglandins, progesterone and indoleamine 2,3-dioxygenase. An undefined factor capable of down-regulating T-cell activity has recently been reported [1] as being produced by short-term cultures of placental fragments. By careful repetition of these studies we have confirmed that chorionic villi isolated from term placenta produce a low molecular weight, heat stable factor capable of inhibiting the IL-2-dependent proliferation of mouse CTLL-2 cells. This activity was not due, however, to a previously unknown immunosuppressive molecule, but rather to prostaglandin E2 (PGE2). Expression of cyclooxygenase (COX)-2 was detected in the syncytiotrophoblast of chorionic villi explants using immunohistochemistry. Culture of the explants in the presence of the COX-1/COX--2 inhibitors indomethacin and diclofenac, or with the COX-2-selective inhibitor DFP, blocked the production of the immunosuppressive factor. The immunosuppressive activity was restored by adding PGE2 to the supernatants obtained from diclofenac-inhibited explants. A number of different receptors are involved in mediating the biological effects of prostaglandins. By utilizing selective antagonists of individual receptors, we have established that the immunosuppressive effect of PGE2 on CTLL-2 cells is exerted via the EP4 receptor. Thus, addition of an EP4-selective antagonist, but not of EP1 or EP3 antagonists, abolished the immunosuppressive effect of PGE2 on CTLL-2 cells. This may have implications for attempts to selectively manipulate T-cell responses.     

Effect of a Water‐Soluble Polymer on Polymer Interdiffusion in P(MMA‐co‐BA) Latex Films

We describe non‐radiative energy‐transfer experiments to measure the rates of polymer interdiffusion in P(MMA‐co‐BA) latex films formed in the presence of poly(vinyl alcohol) (PVOH). PVOH had relatively little effect on the initial efficiency of energy transfer, even when the amount of PVOH was large enough to form the continuous phase. Since Φ_ET(0) is a measure of the interfacial area between D‐ and A‐labeled cells in the film, we conclude that under these circumstances the dispersed P(MMA‐co‐BA) copolymer is in the form of clusters with many contacts between particles containing D and A labels. These large amounts of PVOH also reduce the amount of polymer diffusion that takes place when the films are annealed. When smaller amounts of PVOH are present, the effects are measurable but much smaller. In the presence of 2 to 17 wt.‐% PVOH, the polymer diffusion rate is retarded. The magnitude of the effect increases with the amount of PVOH present, and the effect is larger at 45 °C than at 63 °C. We show that the PVOH has its largest influence at the very early stages of polymer diffusion.

Schematic representation of an energy transfer experiment, which monitors polymer interdiffusion in a latex film.     

Nachweis von α-Mannosidase und β-Glucosidase in einem für die Hefezellwand lytischen System von Streptomyces spec. 5s

Streptomyces spec. 5s accumulates in the culture fluid lytic activities against living cells of Candida guilliermondii H. From the culture fluid a freeze-dried dialyzed ammonium sulfate precipitate was prepared. Except β-glucosidase-activity it showed activity of α-mannosidase which was characterized. Separation of both enzymes by chromatography on polyacrylamide gel was possible.     

Neurotransmitter levels in two populations of larval Fundulus heteroclitus after methylmercury exposure

The effects of methylmercury (MeHg) exposure on neurotransmitter (NT) levels in larval mummichogs (Fundulus heteroclitus) obtained from a mercury-polluted site (Piles Creek (PC), NJ) and a reference site (Tuckerton (TK), NJ) were examined. Population differences between PC and TK larvae in neurochemical composition and in neurochemical changes in response to MeHg intoxication were found. Heads of untreated PC larvae (7 days posthatch (dph)) contained considerably higher levels of dopamine (DA) and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) than TK. However, they had comparable levels of serotonin (5-hydroxytryptamine (5-HT)) and 5-hyroxy-3-indoleacetic acid (5-HIAA)/5-HT ratios. Changes in NTs with age were noticed, especially in PC larvae. Exposure of larvae to 10 microg/l MeHg induced neurochemical alterations. A significant increase in DA and 5-HT, as well as depressed dopaminergic and serotonergic activity (i.e. decreased DOPAC/DA, HVA/DA and 5-HIAA/5-HT ratios) were seen in TK larvae. Exposure of PC larvae to 10 microg/l MeHg reduced 5-HT at 14 dph, increased serotonergic activity at 7 dph, and altered dopaminergic activity (i.e. increased DOPAC/DA ratios, but decreased HVA/DA ratios). Changes in DA levels were inconsistent over time. The DA level, which was considerably higher than the control at 7 dph, was significantly lower than the control at 14 dph. For the two populations, the level of 5-HT and serotonergic activity, as well as DOPAC and HVA levels, were correlated with previously noted spontaneous activity. The changes in NT levels after exposure to MeHg are an indication of neurological dysfunction in larvae.