Siberian ginseng (Eleutheroccus senticosus) effects on CYP2D6 and CYP3A4 activity in normal volunteers.

Siberian ginseng ([SG]; Eleutherococcus senticosus) is a commonly used herbal preparation. The objective of this study was to assess in normal volunteers (n = 12) the influence of a standardized SG extract on the activity of cytochrome P450 CYP2D6 and 3A4. Probe substrates dextromethorphan (CYP2D6 activity) and alprazolam (CYP3A4 activity) were administered orally at baseline and again following treatment with SG (1 x 485 mg twice daily) for 14 days. Urinary concentrations of dextromethorphan and dextorphan were quantified, and dextromethorphan metabolic ratios (DMRs) were determined at baseline and after SG treatment. Likewise, plasma samples were collected (0-60 h) for alprazolam pharmacokinetics at baseline and after SG treatment to assess effects on CYP3A4 activity. Validated high performance liquid chromatography methods were used to quantify all compounds and relevant metabolites. There were no statistically significant differences between pre- and post-SG treatment DMRs indicating a lack of effect on CYP2D6 (P > 0.05). For alprazolam there also were no significant differences in the pharmacokinetic parameters determined by noncompartmental modeling (C(max), T(max), area under the curve, half-life of elimination) indicating that SG does not significantly induce or inhibit CYP3A4 (P > 0.05). Our results indicate that standardized extracts of SG at generally recommended doses for over-the-counter use are unlikely to alter the disposition of coadministered medications primarily dependent on the CYP2D6 or CYP3A4 pathways for elimination.     

Abnormal neuromuscular junctions in the lateral rectus muscle of wobbler mice

We have studied the lateral rectus muscles and neuromuscular junctions (NMJs) of abducens motoneurons in wobbler (wr/wr) mutant mice from 26 to 58 days of age. The muscles of wr/wr weighed about 70% of the weight of littermate controls and were composed of fiber types comparable to those of controls, as assayed by succinate dehydrogenase activity. The most obvious difference between wr/wr and control NMJs was a reduction in the length of the postjunctional membrane of wr/wr mice. The mutant muscle endplate membrane was only about 70% (6.58 micron) the length of control muscle regions (9.44 micron). There were no obvious differences at the light microscopic level in the distribution of acetylcholine (ACh) receptors at junctional regions or staining of acetylcholinesterase, as assayed with alpha-bungarotoxin binding or enzyme histochemistry. Indirect immunocytochemical studies using antibodies directed against the subunits of the ACh receptor failed to indicate an abnormal presence of immature receptors clustered at the NMJs of wr/wr mice. Our findings suggest that the formation or maintenance of normal postjunctional folds and the differentiation of receptors at the junctions are under independent control during development. Furthermore, the wobbler mutation may affect muscle cell differentiation as well as neuronal differentiation. This mutant mouse should prove a useful model for study of postjunctional fold formation and function.     

Interleukin-1 and tumor necrosis factor-mediated regulation of C3 gene expression in human astroglioma cells

In this report, we show that in the human astroglioma cell line D54-MG, both interleukin-1 (IL-1β) and tumor necrosis factor-alpha (TNF-α) enhance C3 gene expression in a time- and dose-dependent manner. Kinetic analysis demonstrates that after 96 h, C3 mRNA levels increase approximately 30-fold and 20-fold in response to IL-1β or TNF-α, respectively. C3 protein production increases proportionally, reaching levels 36-fold and 18-fold higher than untreated controls upon exposure to IL-1β or TNF-α, respectively. D54-MG cells require a minimal 1 h exposure to IL-1β in order to enhance C3 gene expression significantly, while 4 to 8 h are required for TNF-α. Simultaneous treatment of D54-MG cells with IL-1β and interferon-gamma (IFN-γ) resulted in an additive increase in both C3 mRNA and protein expression, a finding not seen with the combination of TNF-α and IFN-γ. Primary rat astrocytes also express increased C3 mRNA levels after 48 h in response to IL-1β (5.3-fold increase) and TNF-α (7-fold increase), while an additive effect was observed upon simultaneous treatment with both IL-1β and IFN-γ. In the central nervous system (CNS), endogenous complement and cytokine production by astrocytes, and enhancement by IFN-γ, a product of activated T cells often seen in the CNS in neural autoimmune disease, may contribute to the pathogenesis of inflammatory demyelinating diseases such as multiple sclerosis.     

Efficacy of Intraoperative Cooling Methods

Background: Patients may require perioperative cooling for a variety of reasons including treatment of a malignant hyperthermia crisis and induction of therapeutic hypothermia for neurosurgery. The authors compared heat transfer and core cooling rates with five cooling methods.

Methods: Six healthy volunteers were anesthetized with desflurane and nitrous oxide. The cooling methods were 1) circulating water (5 [degree sign] Celsius, full-length mattress and cover), 2) forced air (10 [degree sign] Celsius, full-length cover), 3) gastric lavage (500 ml iced water every 10 min), 4) bladder lavage (300 ml iced Ringer's solution every 10 min), and 5) ice-water immersion. Each method was applied for 40 min or until the volunteers' core temperatures approached 34 [degree sign] Celsius. The volunteers were rewarmed to normothermia between treatments. Core cooling rates were evaluated using linear regression.

Results: The first volunteer developed abdominal cramping and diarrhea after gastric lavage. Consequently, the technique was not again attempted. Bladder lavage increased heat loss 10 [nearly =] 10 W and decreased core temperature 0.8 +/- 0.3 [degree sign] Celsius/h (r2 = 0.99 +/- 0.002; means +/- SD). Forced-air and circulating-water cooling comparably increased heat flux, [nearly =] 170 W. Consequently, core cooling rates were similar during the two treatments at 1.7 +/- 0.5 [degree sign] Celsius/h (r2 = 0.99 +/- 0.001) and 1.6 +/- 1.1 [degree sign] Celsius/h (r2 = 0.98 +/- 0.02), respectively. Immersion in an ice water slurry increased heat loss [nearly =] 600-800 W and decreased core temperature 9.7 +/- 4.4 [degree sign] Celsius/h (r sup 2 = 0.98 +/- 0.01). Immersion cooling was associated with an afterdrop of [nearly =] 2 [degree sign] Celsius.     

Characterization and phenotypic analysis of differentiating CD34+human bone marrow cells in liquid culture

Abstract: Our current understanding of human haematopoietic stem cell biology is based in part on the characterization of human CD34⁺ bone marrow cell differentiation in vitro. CD34 is highly expressed on early stem cells and haematopoietic progenitor cells with clonogenic potential and is gradually lost during differentiation and commitment. However, CD71 (transferrin receptor) is expressed at low levels on early stem cells and generally increases during haematopoietic progenitor cell proliferation. We reasoned that the combination of these surface markers would provide a useful framework for the simultaneous analysis of multiple lineage differentiation of CD34⁺ haematopoietic progenitor cells in liquid culture. In this report, we identify the phenotype of distinct subpopulations of myeloid, erythroid and lymphoid cells in liquid suspension culture using differential expression of CD34 vs. CD71 in combination with specific lineage markers. Freshly isolated human CD34⁺ bone marrow cells were introduced into suspension culture and monitored over a 6-d period using 3-colour flow cytometry. This is the first demonstration that differential expression of CD34 vs. CD71 can be used to simultaneously monitor differentiation of multiple haematopoietic cell lineages in liquid suspension culture, facilitating the study of cytokine-, drug- or chemical-induced alterations in haematopoietic progenitor cell differentiation in vitro.     

Silent and multiple mutations in p53 and the question of the hypermutability of tumors [published erratum appears in Carcinogenesis 1998 Jan;19(1):237]

Published data on TP53 mutations can be used to examine the question of whether generalized hypermutability is a necessary condition for tumorigenesis. Although individual mutations do play an etiologic role in tumor formation, the evidence so far does not make it necessary to assume a general mutability. Silent and multiple mutations in the TP53 data set indicate that a special hypermutability process operates on this gene during the generation of tumors. The percentage of silent p53 mutations observed (3%) is at least 20 times greater than would be expected and indicates hypermutability for this gene. The greater proportion of silent mutations among multiple p53 mutations (10%) indicates that the mutations occur nonselectively. The presence of silent mutations implies that not all mutations observed in tumors have an etiologic role. Analysis of the distribution of tumors with two, three, four and more p53 mutations suggests that mutations in some tumors occur in clusters possibly as a result of 'stuttering' in DNA synthesis. It is argued that the most likely alternative explanations of the data, polymorphism and/or a selective role for silent mutations, are not correct. It remains possible that the hypermutability process is restricted to particular genes or to regions of the genome as, for example, in antibody production. There is a surprising paucity of data on human polymorphism and nucleotide diversity which makes the analysis difficult.      

Endothelium-independent Vasoconstricting and Vasodilating Actions of Halothane on Rat Mesenteric Resistance Blood Vessels

Background: Whether volatile anesthetics produce changes in vascular resistance and blood flow because of direct effects on vascular tissue is unclear. Direct vasoconstricting and vasodilating actions have been demonstrated in isolated conductance arteries in vitro, but there is little information regarding direct effects on the small vessels that mediate resistance and flow changes in vivo.

Methods: We investigated the actions of halothane on 50-200 micro Meter branches of the rat mesenteric artery that were cannulated and studied in vitro. The vessels were pressurized to 60 mmHg, and vascular dimensions were continuously monitored using a computer-based real-time image analysis system. The vessel bath was perfused with HCO3 -buffered saline (37 degrees Celsius) equilibrated with 95% Oxygen2 /5% CO2 (plus/minus halothane). The vascular endothelium was mechanically removed before cannulation in some vessels.

Results: In unstimulated vessels, halothane had a concentration-dependent vasoconstricting action (EC50 = 0.45 mM = 1.5 vol% at 37 degrees Celsius) that was largely transient and was similar to that produced by caffeine. Both halothane and caffeine constrictions were unaffected by bath [Calcium2+], nifedipine (1 micro Meter) or Cadmium2+ (100 micro Meter) and were abolished by ryanodine (10 micro Meter). In addition, caffeine responses were attenuated by halothane in a concentration-dependent manner (EC50 - 1.6 mM). In vessels preconstricted with KCl (40 mM) or phenylephrine (10 sup -6 M), halothane produced transient constriction followed by concentration-dependent vasodilation. Ryanodine, which abolished halothane constrictions, had little effect on the amplitude of KCl- or phenylephrine-induced constrictions or the vasodilating action of halothane. Removal of the endothelium likewise had little effect on the vasoconstricting or the vasodilating actions of halothane in unstimulated, KCl- or phenylephrine-constricted vessels. Halothane completely relaxed KCl and phenylephrine constrictions with EC50 values of 0.36 mM (1.2% at 37 degrees Celsius) and 0.75 mM (2.5%), respectively, in intact vessels before ryanodine; 0.25 mM (0.8%) and 0.59 mM (1.9%) in intact vessels after ryanodine; and 0.52 mM (1.7%) and 0.67 mM (2.2%) in endothelium-denuded vessels.     

A pilot study of a parent-education group for families affected by depression.

OBJECTIVE: This study assessed the feasibility and efficacy of a parent-education group for families with young children and a parent with depression. We designed the program to be readily disseminated if shown to be effective. METHOD: We recruited 44 parents with depression from clinics and family doctors in Hamilton, Ontario, and randomly assigned them to receive the parenting program or to a wait-list control group. The outcomes measured included knowledge of depression, parenting, family relationships, depression symptoms, child depressive symptoms, and functioning. We used analysis of covariance to test for posttreatment differences between experimental and control groups. RESULTS: Of the treatment group, 27% dropped out at posttreatment, and 43% by follow-up. Those who dropped out had more severe depression at baseline than did those who completed the program, and there was selective loss of parents with more severe depression in the experimental group. In intention-to-treat analyses at posttreatment, probands in the experimental group reported more improvements on family functioning, parenting sense of competence, and family and parent conflict than did control subjects. Standardized effect sizes (ES) were medium (0.4 to 0.6). When baseline depressive symptom scores were controlled in the analyses, the between-group differences were reduced, showing that selective loss of participants may have influenced the findings. CONCLUSIONS: On balance, the results are encouraging and support the further development and evaluation of the group intervention. However, the study does not provide unequivocal evidence in support of the program. Before it is transferred to other settings, the program needs further modification to improve participation by parents with more severe depression and further evaluation of its effectiveness.