Assessment of hepatic function in cystic fibrosis by lidocaine metabolism.

BACKGROUND: To determine hepatic drug metabolism in patients with cystic fibrosis, as measured by monoethylglycinexylidide formation after lidocaine injection and indocyanine green (ICG) clearance. METHODS: The following study is a case-control study, which included 19 patients with cystic fibrosis and 13 control subjects. Serum monoethylglycinexylidide concentration was measured after intravenous injection of 1 mg/kg (maximum, 50 mg) lidocaine. Indocyanine green (0.5 mg/kg) was injected concomitantly, and absorbance (805 nm) of serum was measured over time to determine its volume of distribution, serum half-life, and hepatic blood flow. RESULTS: Monoethylglycinexylidide formation was decreased in patients with cystic fibrosis compared with controls (39.4+/-16.9 microg/L versus 70.3+/-45.7 microg/L, mean +/- SD, respectively, P < 0.02). Indocyanine green half-life (4.6+/-2.7 min versus 3.0+/-1.0 min), volume of distribution (8.6+/-5.5 L versus 8.3+/-3.4 L), and hepatic blood flow (10.9+/-5.9 ml x kg(-1) x min(-1) versus 7.4+/-2.0 ml x kg(-1) x min(-1)) were similar in both groups. CONCLUSION: Monoethylglycinexylidide formation after lidocaine injection is impaired in patients with cystic fibrosis. This impairment may have clinical implications when using hepatically metabolized medications in patients with cystic fibrosis.

Herpetic croup: two case reports and a review of the literature.

Croup is an acute infectious illness usually occurring in children; it is characterized by brassy cough and stridor. The main pathogens include mainly parainfluenza and influenza viruses. Recently there have been reports of prolonged croup caused by the herpes simplex viruses. We report two cases of prolonged croup due to herpes simplex types 1 and 2. We also review and summarize the reported pediatric cases of herpetic croup.

Inhibition of T-lymphocyte activation by amiloride.

The T-lymphocyte activation process involves a series of coordinately coupled biochemical events occurring in response to antigen or mitogen. These events have not been completely characterized. The present studies investigate the mechanism of protein synthesis during the initial phase of T-cell activation. Among the early biochemical changes, induction of protein synthesis was observed as early as 10 minutes after mitogen stimulation of T-lymphocytes. This early protein synthesis was inhibited by cycloheximide but was insensitive to actinomycin-D, indicating the presence of preformed mRNA in resting lymphocytes. Since early protein synthesis parallels the increase in protein kinase C activity in activated T-lymphocytes, these two biochemical events may be related. In the present report, amiloride, an inhibitor of Na+/H+ antiport and protein kinase C, significantly inhibited [3H]leucine and [3H]thymidine incorporation in a dose-dependent manner into phytohemagglutinin (PHA)-stimulated T-lymphocytes. Furthermore, when T-lymphocytes were stimulated by phorbol myristate acetate, a known activator of protein kinase C, a similar inhibition of protein and DNA synthesis by amiloride was observed. The partially purified cytosol fraction isolated from PHA-activated T-lymphocytes showed a 75% decrease in protein kinase C-mediated [32P] incorporation from ATP in the presence of 100 microM amiloride. These results suggest that the T-cell activation process following exposure to mitogens involves early protein synthesis, which may be mediated by protein kinase C.

Effect of polymyxin-B on T-lymphocyte protein synthesis.

The role of protein kinase-C (PK-C) protein phosphorylation on the mitogen triggered responses of T-lymphocytes was examined by observing the effect of polymyxin-B (an inhibitor of PK-C) on mitogen induced protein and DNA synthesis. Polymyxin-B inhibited 3H-thymidine incorporation by PHA activated T-lymphocytes over a range of PHA concentrations. 3H-leucine incorporation by PHA activated T-lymphocytes was inhibited by polymyxin-B in a dose dependent manner. A partially purified PK-C fraction from polymyxin-B treated PHA activated T-lymphocytes demonstrated less than 25% of the phosphorylating activity of untreated lymphocytes. These results suggest that protein synthesis during the T-lymphocyte activation process is dependent on PK-C activity.

Severe combined immunodeficiency with natural killer-cell predominance: abrogation of graft-versus-host disease and immunologic reconstitution with HLA-identical bone marrow cells.

A 3 1/2-month-old infant with severe combined immunodeficiency was found to have an unusual blood lymphocyte phenotype. Thirty percent of her cells formed rosettes with sheep erythrocytes, but only 7.9% reacted with the pan T monoclonal antibody OKT3, and 5% reacted with an antibody (OKT4)-recognizing T-helper cells. Surprisingly 19.4% of her cells reacted with an antibody (OKT8)-recognizing T-suppressor cells and 94% reacted with OKT10 . Few reacted with other monoclonal antibodies detecting cellular activation antigens. Despite absence of T or B cell function, her monocyte-depleted blood lymphocytes caused a high degree of specific lysis of 51Cr-labeled K562 erythromyeloid cells in a natural killer-cell assay. Most of her lymphocytes were large and had azurophilic granules and a monocytoid nucleus. Because she had received a nonirradiated, unrelated red-cell transfusion 3 days earlier, 4.8 X 10(9) nucleated bone-marrow cells from her HLA-identical brother were given shortly after admission. Two days later a graft-versus-host reaction began but subsided completely within 3 days. On day 15 posttransplantation, a profuse secretory diarrhea began, accompanied by a rise in her serum IgE from 4 to 3000 IU. With engraftment, the number of T10+ cells and natural killer-cell function fell to normal, and full immunologic reconstitution was achieved.