Effects of a quick-release form of bromocriptine (Ergoset) on fasting and postprandial plasma glucose, insulin, lipid, and lipoprotein concentrations in obese nondiabetic hyperinsulinemic women

OBJECTIVE: To assess the effect on various aspects of carbohydrate and lipid metabolism of administering a quick-release formulation of bromocriptine (Ergoset) to obese, nondiabetic, hyperinsulinemic women. RESEARCH DESIGN AND METHODS: Hourly concentrations of prolactin, glucose, insulin, free fatty acid (FFA), and triglyceride were measured for 24 h before and after approximately 8 weeks of treatment with Ergoset. In addition, fasting lipid and lipoprotein concentrations and the steady-state plasma glucose (SSPG) concentration in response to a continuous infusion of somatostatin, insulin, and glucose were determined before and after Ergoset administration. RESULTS: Circulating prolactin concentrations were dramatically decreased (P < 0.001) following treatment, associated with a significant fall (P < 0.05) in 24-h-long plasma glucose, FFA, and triglyceride concentrations. Neither circulating plasma insulin concentrations nor the ability of insulin to mediate glucose disposal changed with treatment. Finally, fasting total cholesterol fell (P < 0.05) and the ratio of total to HDL cholesterol decreased (P = 0.06) in association with Ergoset treatment. CONCLUSIONS: The fact that significant metabolic improvement was seen in the obese nondiabetic hyperinsulinemic women studied suggests that Ergoset could be of therapeutic benefit in clinical conditions of hyperglycemia and/or dyslipidemia.     

Neurovisceral integration in cardiac and emotional regulation

The utility of heart-rate variability (HRV) to index important aspects of neural control of the heart has made it one of the most valuable tools for researchers interested in health and behavior. However, most of the literature and extant data on the central origins of HRV have been derived from animal models. As yet little is known about the central nervous system (CNS) origins and concomitants in humans. In the following we will briefly detail a set of neural structures that have been associated with important CNS functions including cardiac regulation and emotional regulation. We will briefly summarize recent data using pharmacological, neuroimaging, and psychophysiological techniques that have examined CNS concomitants of HRV especially during emotion. Based on these and other data will we report the results of a computational model that examined the interactions of several neural structures and their effect on emotion-related HRV.     

Testing an implantable intraspinal drug delivery device in the ewe

OBJECTIVE: The authors report the use of multiple implanted intraspinal port and catheter systems per test animal to study the in vivo functional characteristics and reliability of a new implantable spinal drug delivery port system. METHODS: Four ewes were each implanted with two epidural and one subarachnoid silicone elastomer catheters at the lumbar level. Each catheter was connected in series to one of three Therex filtered spinal delivery ports implanted subcutaneously in a similar grid pattern in each ewe to facilitate percutaneous identification. Saline (2 ml) was injected 3 times weekly in each port. The ease of injection and behavioral responses were recorded for 207-213 days of implantation until sacrifice/necropsy. RESULTS: All ports functioned reliably during the study. However, injection through two of the four subarachnoid catheters resulted in behavioral withdrawal responses intermittently. This behavioral pattern was much less common after epidural port injections. All four subarachnoid and four of eight epidural port and catheter systems were tested with local anesthetic just before sacrifice. Motor block was observed in three of four subarachnoid and three of four epidural port and catheter systems tested. Integrity of the other four epidural ports was tested by injection of methylene blue at sacrifice. This dye did not distribute in the epidural space in one of the latter four epidural ports (not local anesthetic tested) because of a concentric fibrotic reaction about the catheter. Similar fibrotic reactions surrounded the catheters that failed a functional test with local anesthetic. CONCLUSIONS: The implantable intraspinal port system tested functions reliably under repetitive percutaneous access. However, filtering such ports, though desirable to prevent entry of debris into the spinal canal, did not eliminate pericatheter chronic subarachnoid and epidural reaction. The number of test animals required to test 12 ports chronically was reduced by two-thirds without undue trauma to the individual test subject. Chronic percutaneous injection of an implanted subarachnoid system is feasible but may be associated with behavioral effects similar to that seen with chronic epidural systems. Fibrosis around chronic silicone catheters limited functional utility in one-fourth of the implanted test systems. Further study of the potential reactivity of chronic epidural and subarachnoid catheters is indicated.     

Characterization of EspC, a 110-kilodalton protein secreted by enteropathogenic Escherichia coli which is homologous to members of the immunoglobulin A protease-like family of secreted proteins

Enteropathogenic Escherichia coli (EPEC) secretes at least five proteins. Two of these proteins, EspA and EspB (previously called EaeB), activate signal transduction pathways in host epithelial cells. While the role of the other three proteins (39, 40, and 110 kDa) remains undetermined, secretion of all five proteins is under the control of perA, a known positive regulator of several EPEC virulence factors. On the basis of amino-terminal protein sequence data, we cloned and sequenced the gene which encodes the 110-kDa secreted protein and examined its possible role in EPEC signaling and interaction with epithelial cells. In accordance with the terminology used for espA and espB, we called this gene espC, for EPEC-secreted protein C. We found significant homology between the predicted EspC protein sequence and a family of immunoglobulin A (IgA) protease-like proteins which are widespread among pathogenic bacteria. Members of this protein family are found in avian pathogenic Escherichia coli (Tsh), Haemophilus influenzae (Hap), and Shigella flexneri (SepA). Although these proteins and EspC do not encode IgA protease activity, they have considerable homology with IgA protease from Neisseria gonorrhoeae and H. influenzae and appear to use a export system for secretion. We found that genes homologous to espC also exist in other pathogenic bacteria which cause attaching and effacing lesions, including Hafnia alvei biotype 19982, Citrobacter freundii biotype 4280, and rabbit diarrheagenic E. coli (RDEC-1). Although these strains secrete various proteins similar in molecular size to the proteins secreted by EPEC, we did not detect secretion of a 110-kDa protein by these strains. To examine the possible role of EspC in EPEC interactions with epithelial cells, we constructed a deletion mutant in espC by allelic exchange and characterized the mutant by standard tissue culture assays. We found that EspC is not necessary for mediating EPEC-induced signal transduction in HeLa epithelial cells and does not play a role in adherence or invasion of tissue culture cells.     

Inhibition of anthracycline semiquinone formation by ICRF-187 (dexrazoxane) in cells

The formation of semiquinone free radicals of doxorubicin, epirubicin, daunorubicin, and idarubicin was measured by electron paramagnetic resonance (EPR) spectroscopy in hypoxic suspensions of chinese hamster ovary (CHO) cells. The amount of semiquinone produced was in the order idarubicin > doxorubicin > daunorubicin > epirubicin. The idarubicin semiquinone signal was both the fastest to be formed and to decay. Idarubicin, which was the most lipophilic of the anthracyclines studied, also displayed the fastest fluorescence-measured cellular uptake of drug. Thus, it was concluded that semiquinone formation was dependent upon the rate of cellular uptake. Lysed cell suspensions were also shown to be capable of producing the doxorubicin semiquinone in the presence of added NADPH. The cardioprotective agent dexrazoxane (ICRF-187) was observed to decrease the amount of doxorubicin semiquinone observed in cell suspensions. Dexrazoxane also decreased the amount of doxorubicin semiquinone observed in the NADPH-lysed cell suspension mixture. Neither bipyridine nor deferoxamine decreased NADPH-dependent doxorubicin semiquinone formation. These results suggest that dexrazoxane does not decrease doxorubicin semiquinone formation through an iron complex formed from hydrolyzed dexrazoxane. Dexrazoxane may be inhibiting an NADPH-dependent enzyme.     

Paresthesias: a practical diagnostic approach

Filarial nematodes are a cause of chronic debilitating diseases in the tropics. A hallmark of filariasis is the marked down-regulation and polarization of host immune responses, yet molecular constituents of parasites causing this state have remained undefined. We describe a 17-kDa antigen (Av17) of the rodent filarial parasite Acanthocheilonema viteae, which shows amino acid homologies to cystatin C, a major cysteine protease inhibitor belonging to family 2 of the cystatin superfamily. Av17 is released by filariae in vitro. Exported molecules of A. viteae worms are shown to markedly suppress mitogen-induced T cell proliferation of mice and jirds. Av17 accounts for 45.5% of this suppressive activity in the murine system. Recombinant Av17 (rAv17), expressed in Escherichia coli, exhibits biological activity as a cysteine protease inhibitor and was used to examine the immunomodulatory effects, rAv17 induces down-regulation of murine T cell responses to mitogens, to T cell receptor cross-linking by anti-CD3 antibodies and to specific antigens, and at the same time up-regulation of interleukin-10. Hence, this filarial cystatin is a likely effector molecule of immunomodulation and a potential target for antifilarial intervention.     

New energy transfer dyes for DNA sequencing

We have synthesized a set of four energy transfer dyes and demonstrated their use in automated DNA sequencing. The donor dyes are the 5- or 6-carboxy isomers of 4'-aminomethylfluorescein and the acceptor dyes are a novel set of four 4,7-dichloro-substituted rhodamine dyes which have narrower emission spectra than the standard, unsubstituted rhodamines. A rigid amino acid linker, 4-aminomethylbenzoic acid, was used to separate the dyes. The brightness of each dye in an automated sequencing instrument equipped with a dual line argon ion laser (488 and 514 nm excitation) was 2-2.5 times greater than the standard dye-primers with a 2 times reduction in multicomponent noise. The overall improvement in signal-to-noise was 4- to 5-fold. The utility of the new dye set was demonstrated by sequencing of a BAC DNA with an 80 kb insert. Measurement of the extinction coefficients and the relative quantum yields of the dichlororhodamine components of the energy transfer dyes showed their values were reduced by 20-25% compared with the dichlororhodamine dyes alone.     

Pulmonary carcinogenicity of relatively low doses of beta-particle radiation from inhaled 144CeO2 in rats

This study was conducted to examine the carcinogenic effects of inhaled beta-particle-emitting radionuclides, particularly in lower dose regions in which there were substantial uncertainties associated with available information. A total of 2751 F344/N rats (1358 males and 1393 females) approximately 12 weeks of age at exposure were used. Of these, 1059 rats were exposed to aerosols of 144CeO2 to achieve mean desired initial lung burdens (ILBs) of 18 kBq (low level), 247 rats to achieve mean ILBs of 60 kBq (medium level) and 381 rats to achieve mean ILBs of 180 kBq (high level). Control rats (total of 1064) were exposed to aerosols of stable CeO2. Based on the 95% confidence intervals of the median survival times and the cumulative survival curves, there were no significant differences in the survival of groups of female and male exposed rats relative to controls. The mean lifetime beta-particle doses to the lungs of the rats in the four groups were: low level, 3.6 +/- 1.3 (+/-SD) Gy; medium level, 12 +/- 4.5 Gy; and high level, 37 +/- 5.9 Gy. The crude incidence of lung neoplasms increased linearly with increasing doses to the lungs (controls, 0.57%; low level, 2.0%; medium level, 6.1%; and high level, 19%). The estimated linear risk coefficients for lung neoplasms per unit of dose to the lung were not significantly different for the three dose levels studied. The risk coefficient at the lower level was 39 +/- 14 (+/-SE) excess lung neoplasms per 10(4) rat Gy; at the medium level the risk was 47 +/- 12; and at the higher level the risk was 50 +/- 9.0. The relationship of beta-particle dose to the lung and the crude incidence of lung neoplasms was described adequately by a linear function. We concluded that the risk of lung neoplasms in rats per unit of radiation dose did not increase with decreasing mean beta-particle dose to the lung over the range of 3.6 to 37 Gy. The weighted average of these three values was 47 +/- 6.4 (+/-SE) excess lung neoplasms per 10(4) rat Gy. To extend the risk coefficients for lung neoplasms to lower doses by experimentation will require much larger numbers of rats than used in this study.