The market made them do it. Participants in the Medicare Choices project say they're nudging out the insurance middleman--and insuring their own survival. Panel discussion

Medicare is experimenting again. This time HCFA wants to figure out ways to expand managed care options for the elderly. Under the Medicare Choices Demonstration Project, hospitals and health systems are developing and testing alternatives to standard Medicare HMOs. Dick Davidson, president of the American Hospital Association, sees these pilot programs as the precursors to provider-sponsored organizations building up a base of knowledge about what it means to manage risk. The AHA recently convened a meeting of organizations involved in the demonstration project and asked Hospitals & Health Networks executive editor Alden Solovy to lead a panel discussion on the lessons being learned.

Analytical Debye-Huckel model for electrostatic potentials around dissolved DNA

We present an analytical, Green-function-based model for the electric potential of DNA in solution, treating the surrounding solvent with the Debye-Huckel approximation. The partial charge of each atom is accounted for by modeling DNA as linear distributions of atoms on concentric cylindrical surfaces. The condensed ions of the solvent are treated with the Debye-Huckel approximation. The resultant leading term of the potential is that of a continuous shielded line charge, and the higher order terms account for the helical structure. Within several angstroms of the surface there is sufficient information in the electric potential to distinguish features and symmetries of DNA. Plots of the potential and equipotential surfaces, dominated by the phosphate charges, reflect the structural differences between the A, B, and Z conformations and, to a smaller extent, the difference between base sequences. As the distances from the helices increase, the magnitudes of the potentials decrease. However, the bases and sugars account for a larger fraction of the double helix potential with increasing distance. We have found that when the solvent is treated with the Debye-Huckel approximation, the potential decays more rapidly in every direction from the surface than it did in the concentric dielectric cylinder approximation.

Differentiation of hypoglycaemia induced cognitive impairments. An electrophysiological approach

Effects of hypoglycaemia on distinct cognitive processes were assessed with event-related brain-potential (ERP) measures and reaction times in a hybrid selective-attention/response-choice task. One group of subjects received a euglycaemia-hypoglycaemia-euglycaemia treatment order and a second group a euglycaemia-placebo(euglycaemia)-euglycaemia sequence of treatments. During hypoglycaemia, ERP measures of selective attention (selection negativity), response choice (lateralized readiness potential) and reaction time were delayed compared with baseline performance. After restoration of euglycaemia, the onset of the selection negativity returned to baseline, whereas the lateralized readiness potential was still delayed, and error frequencies remained elevated. These results suggest that hypoglycaemia delays both the stimulus selection and the motor-response selection. They further suggest that the stimulus-selection process recovers quickly after restoration of euglycaemia, but that the response-selection process does not. Slow shifts in cortical potentials with a broad frontal distribution that occurred during hypoglycaemia, are discussed in relation to frontal lobe mechanisms involved in the control of subordinate, modality-specific selection mechanisms.

Demonstration of the therapeutic potential of non-anaphylactogenic anti-IgE antibodies in murine models of skin reaction, lung function and inflammation

BACKGROUND

Allergies and allergic asthma are believed to be mediated by allergen-specific IgE antibodies. We have investigated the therapeutic potential of inhibiting endogenous IgE by a non-anaphylactogenic anti-mouse IgE antibody 1-5 with respect to its effects on antigen-induced skin reaction, lung function changes and lung inflammation in mice.

METHODS

Mice were immunized with benzylpenicillinoyl-KLH or ovalbumin, and antigen-mediated skin reaction, bronchoconstriction, bronchopulmonary hyperresponsiveness (BHR) and lung eosinophilic inflammation determined in anti-IgE 1-5-treated versus untreated animals.

RESULTS

Application of anti-IgE 1-5 inhibited (by 90%) the serum IgE and, 3-4 days after onset of treatment, blocked the antigen-induced skin reaction. Furthermore, the antibody also inhibited (by 90%) the antigen-induced infiltration of eosinophils into the lung. This latter effect seems to be mediated by blocking the IgE-CD23 interaction and indicates that lung eosinophilic inflammation also depends on IgE. Moreover, when applied to rats passively sensitized with mouse IgE, antibody 1-5 inhibited the antigen-induced bronchoconstriction. A similar effect could be seen in actively immunized mice, where antibody 1-5 was able to inhibit (by 70%) the ovalbumin-induced bronchoconstriction as well as BHR.

CONCLUSIONS

In summary, non-anaphylactogenic anti-IgE antibodies can markedly inhibit IgE levels and IgE-mediated allergic reactions. Since bronchoconstriction, BHR and lung eosinophilic inflammation can be suppressed, such antibodies may be attractive principles for the treatment of allergic asthma.

New-onset diabetes mellitus in pediatric thoracic organ recipients receiving tacrolimus-based immunosuppression

BACKGROUND

Tacrolimus has a negative effect on the pancreatic beta islet cell, and both glucose intolerance and diabetes mellitus are well-recognized complications of tacrolimus-based immunosuppression among adult solid organ transplant recipients.

METHODS

To determine the association between tacrolimus and new-onset diabetes mellitus in childhood, we reviewed data on 78 pediatric heart and heart-lung/lung recipients receiving tacrolimus-based immunosuppression. Trough tacrolimus levels, fasting and random blood glucose levels, and corticosteroid requirements were reviewed. Diabetes was defined as glucose intolerance requiring long-term insulin treatment more than 30 days after transplantation.

RESULTS

No patient had diabetes before introduction of tacrolimus. In heart-lung/lung recipients, 12 of 28 (43%) had development of diabetes at a median follow-up of 7 months (range 1 to 39). In this group diabetes developed in three of eight (38%) patients with cystic fibrosis and nine of 20 (45%) without (p = NS). In contrast, only two of 50 (4%) heart transplant recipients had development of diabetes. Of the 14 patients with diabetes, 10 had development of diabetes during augmentation of immunosuppression with pulsed corticosteroids. Tacrolimus trough levels were significantly lower in heart compared with heart-lung/lung transplant recipients (9.4 +/- 3.3 versus 15.3 +/- 0.9 ng/ml) (p < 0.01), and at latest follow-up significantly fewer heart transplant recipients were treated with maintenance corticosteroids (28% versus 75%; p < 0.01). In the heart-lung/lung group, no significant difference in tacrolimus levels was found between patients with and without diabetes, nor was there a significant difference in the average corticosteroid dose or number of pulses of corticosteroids per patient.

CONCLUSIONS

New-onset diabetes mellitus is rare in pediatric heart transplant recipients receiving tacrolimus-based immunosuppression, but it occurs with a high incidence after pediatric heart-lung/lung transplantation and usually develops during pulsed corticosteroid therapy. However, it is currently not possible to predict which heart-lung/ lung transplant recipients will have development of this serious complication.

Influence of duodenal infusion of nicotinic acid on the milk fat composition of dairy cows

Two experiments I and II, with 2 and 4 lactating dairy cows respectively, each fistulated with ruminal and duodenal cannulae, were carried out. The effects on milk composition and milk fat fatty acids' pattern through a continuous daily infusion into the duodenum with 6 g nicotinic acid were investigated. Treatments were nicotinic acid (NA) infusion in experiment I, and nicotinic acid infusion plus feeding 270 g of stearic acid in experiment II. No application of NA and stearic acid in experiments I and II respectively, acted as controls. Nicotinic acid infusion did not significantly influence protein, fat and lactose contents of milk. In both experiments, infusion of nicotinic acid decreased the proportion of short and middle chain fatty acids in milk fat and increased significantly the percentage of oleic acid from 19.0 to 25.4%. The addition of stearic acid alone had no effect on milk composition and fatty acids' pattern. Additional infusion of nicotinic acid infusion significantly increased nicotinamid concentration in the milk from 49.7 to 87.2 micrograms/100 ml.