Concentration-dependent metabolism of diazepam in mouse liver

Previous mouse liver studies with diazepam (DZ),N-desmethyldiazepam (NZ), and temazepam (TZ) confirmed that under first-order conditions, DZ formed NZ and TZ in parallel. Oxazepam (OZ) was generatedvia NZ and not TZ despite that preformed NZ and TZ were both capable of forming OZ. In the present studies, the concentration-dependent sequential metabolism of DZ was studied in perfused mouse livers and microsomes, with the aim of distinguishing the relative importance of NZ and TZ as precusors of OZ. In microsomal studies, theK _ms andV _maxs, corrected for binding to microsomal proteins, were 34 μM and 3.6 nmole/min per mg and 239 μM and 18 nmole/min per mg, respectively, forN-demthylation andC ₃-hydroxylation of DZ. TheK _ms andV _maxs forN-demethylation andC ₃-hydroxylation of TZ and NZ, respectively, to form OZ, were 58 μM and 2.5 nmole/min per mg and 311 μM and 2 nmole/min per mg, respectively. The constants suggest that at low DZ concentrations, NZ formation predominates and is a major source of OZ, whereas at higher DZ concentrations, TZ is the important source of OZ. In livers perfused with DZ at input concentrations of 13 to 35 μM, the extraction ratio of DZ (E{DZ}) decreased from 0.83 to 0.60. NZ was the major metabolite formed although its appearance was less than proportionate with increasing DZ input concentration. By contrast, the formation of TZ increased disporportionately with increasing DZ concentration, whereas that for OZ decreased and paralleled the behavior of NZ. Computer simulations based on a tubular flow model and thein vitro enzymatic parameters provided a poorin vitro-organ correlation. TheE{DZ}, appearance rates of the metabolites, and the extraction ratio of formed NZ (E{NZ, DZ}) were poorly predicted; TZ was incorrectly identified as the major precursor of OZ. Simulations with optimized parameters imporved the correlations and identified NZ as the major contributor of OZ. Saturation of DZN-demethylation at higher DZ concentrations increased the role of TZ in the formation of OZ. The poor aqueous solubility (limiting the concentration range of substrates usedin vitro), avid tissue binding and the coupling of enzymatic reactions in liver, favoring sequential metabolism, are possible explanations for the poorin vitro-organ correlation. This work emphasizes the complexity of the hepatic intracellular milieu for drug metabolism and the need for additional modeling efforts to adequately describe metabolite kinetics. This work was supported by the Medical Research Council of Canada (MA-9104).     

Bring me home: Renal dialysis in the Kimberley

SUMMARY:   The incidence of end-stage renal failure (ESRF) in the Kimberley region at the top end of Western Australia far exceeds known national rates and trend analysis demonstrates a close parallel to what is occurring in the Northern Territory. Dialysis prevalence in the Kimberley has nearly tripled in the last decade and has increased at a much faster rate than the rest of Western Australia. Almost all of these people with ESRF are Aboriginal Australians living in remote communities.
In January 2004, the Western Australia Country Health Service and Kimberley Aboriginal Medical Services' Council, under the auspices of the Kimberley Aboriginal Health Planning Forum, embarked upon a review of renal disease in the Kimberley funded by the Western Australia Department of Health. The main purpose of the review was to identify the scope of the problem and make projections upon which to base programme and service development over the next 10 years.
This paper outlines the findings of the Review of Renal Disease in the Kimberley and presents, for the first time, regional data analysis and comparisons. In addition, future projections on the impact of ESRF and recommendations for improving current service delivery are discussed. Given the challenges of remoteness and individuals' desire to return home, this review recommends development of locally-based expertise capable of providing training and support to patients and their families, reinvigoration of community-based dialysis modalities, and the initiation of planning for a second satellite service in the Kimberley.     

Interleukin 6 Influences Germinal Center Development and Antibody Production via a Contribution of C3 Complement Component

Mice rendered deficient for interleukin (IL) 6 by gene targeting were evaluated for their response to T cell–dependent antigens. Antigen-specific immunoglobulin (Ig)M levels were unaffected whereas all IgG isotypes showed varying degrees of alteration. Germinal center reactions occurred but remained physically smaller in comparison to those in the wild-type mice. This concurred with the observations that molecules involved in initial signaling events leading to germinal center formation were not altered (e.g., B7.2, CD40 and tumor necrosis factor R1). T cell priming was not impaired nor was a gross imbalance of T helper cell (Th) 1 versus Th2 cytokines observed. However, B7.1 molecules, absent from wild-type counterparts, were detected on germinal center B cells isolated from the deficient mice suggesting a modification of costimulatory signaling. A second alteration involved impaired de novo synthesis of C3 both in serum and germinal center cells from IL-6–deficient mice. Indeed, C3 provided an essential stimulatory signal for wild-type germinal center cells as both monoclonal antibodies that interrupted C3-CD21 interactions and sheep anti–mouse C3 antibodies caused a significant decrease in antigen-specific antibody production. In addition, germinal center cells isolated from C3–deficient mice produced a similar defect in isotype production. Low density cells with dendritic morphology were the local source of IL-6 and not the germinal center lymphocytes. Adding IL-6 in vitro to IL-6–deficient germinal center cells stimulated cell cycle progression and increased levels of antibody production. These findings reveal that the germinal center produces and uses molecules of the innate immune system, evolutionarily pirating them in order to optimally generate high affinity antibody responses.     

What Factors in Early Pregnancy Indicate that the Mother Will Be Hit by Her Partner during the Year after Childbirth?A Nationwide Swedish Survey

Abstract: Background : To be hit by one's intimate partner during the first year after childbirth may affect a woman's health and ability to take care of her newborn. The purpose of this study was to document the prevalence and indicators in early pregnancy of a woman being hit by her partner during the year after childbirth. Method : Information was collected by a postal questionnaire in early pregnancy and 12 months after childbirth from the approximately 5,550 women in Sweden who visited an antenatal care clinic for the first time during one of three chosen weeks in 1999 and 2000. Results : Of the 3,266 recruited women, 2,563 returned the follow‐up questionnaire. Being hit during the first year after childbirth was reported by 52 of the 2,563 (2%) women: 32 (61%) had been hit by their partner once, 12 (23%) twice, and 8 (15%) three or more times. Risk increased in women who were age 24 years or younger (3.9% had been hit), unmarried (7.1%), born in countries outside Europe (6.8%), with a partner born outside Europe (5.4%), had a low level of education (8.9%), and were unemployed (5.0%). In early pregnancy, women with back pain (4.0%), a chronic illness (4.1%), coital pain (6.1%), frequent depression‐related symptoms (8.1%), stomach pain (3.8%), or a urinary tract problem (6.3%) were hit more often than others after childbirth. Conclusions : At least 2 percent of Swedish women giving birth in 2000 were hit by their partner during the year after childbirth. Using identified predictors during antenatal care may increase the likelihood of finding women at risk, thereby enhancing the possibility of interventions to prevent this crime and health hazard.     

Immunophenotyping of childhood acute lymphoblastic leukemia in Saudi Arabia: Second look

Geographical variations in the incidence of disease are of considerable theoretical and practical importance. It has been claimed that the distribution of acute lymphoblastic leukemia (ALL) phenotypes in Saudi Arabia is different from that recorded in the Western literature. One hundred and twelve (112) patients under 15 years of age, diagnosed as ALL between January 1992 and May 1994 had immunophenotypes performed on their blast cells. Common ALL (cALL) together with pre-B-ALL, formed 86.5% of the total; B-cell 3%, T-cell 6% and null cell 4.5%. These figures are not significantly different from the Western literature. A previous claim from this institution in 1990, that both null and B-cell ALL were significantly increased compared with elsewhere, is not supported by the present figures. Age and sex distribution, and FAB classification, L1 77%, L2 20% and L3 3%, were also of the same order as described elsewhere and, in particular, there was no increase in the frequency of L3 subtype.     

ASSESSING THE IMPACT OF A CHILD WITH SPINA BIFIDA ON THE FAMILY

This study examined the characteristics of families which may be more vulnerable than others to the impact of caring for a child with spina bifida. Morbidity and the use of health services were unexpectedly high. The impact on the family was related less to clinical diagnoses than to the characteristics of the child's functioning in the home and of the family. Major predictors of greater impact on the family were the number of the child's activities of daily living, parental perceptions of the child's health, low maternal educational attainment, low family income, the number of adults in the family, insurance status, the number of visits to a doctor in the month before the interview, and whether the adults in the family were employed. These results reinforce the need for assessments to include the child's function in the home, and for additional resources to help some families care for their child.     

Sample size considerations when groups are the appropriate unit of analysis.

This article discusses issues to be considered by nurse researchers when groups should be used as the unit of randomization. Advantages and disadvantages are presented, with statistical calculations needed to determine the effective sample size. Examples of these concepts are presented using data from the Black Cosmetologists Promoting Health Program. Different hypothetical scenarios and their impact on sample size are also presented. Given the complexity of calculating the sample size when using groups as the unit of randomization, it is advantageous for researchers to work closely with statisticians when designing and implementing studies that anticipate the use of groups as the unit of randomization.     

Glucokinase and cytosolic phosphoenolpyruvate carboxykinase (GTP) in the human liver. Regulation of gene expression in cultured hepatocytes.

Glucokinase and phosphoenolpyruvate carboxykinase are key enzymes of glucose metabolism in the rat liver. The former is considered to be instrumental in regulating glucose hepatic release/uptake according to the glycaemia level, and cytosolic phosphoenolpyruvate carboxykinase is a major flux-generating enzyme for gluconeogenesis. The level of expression of both enzymes and the regulation of their mRNAs in the human liver cell were investigated. Surgical biopsies of liver from patients undergoing partial hepatectomies and parenchymal hepatocytes derived from the biopsies were used to assay glucokinase, hexokinase and phosphoenolpyruvate carboxykinase activities. Hepatocytes were placed in culture and the actions of insulin, glucagon and cAMP on glucokinase and phosphoenolpyruvate carboxykinase mRNAs were studied. The main results are: (a) glucokinase accounts for 95% of the glucose phosphorylation activity of human hepatocytes, although this fact is masked in assays of total liver tissue; (b) glucokinase activity is set at a lower level in human hepatocytes than in rat hepatocytes, and vice-versa for the gluconeogenic enzyme phosphoenolpyruvate carboxykinase; and (c) as previously shown in rat liver, glucokinase and phosphoenolpyruvate carboxykinase mRNAs are regulated in a reciprocal fashion in human hepatocytes, insulin inducing the first enzyme and repressing the latter, whereas glucagon has opposite effects. These data have interesting implications with respect to metabolic regulation and intracellular hormone signaling in the human liver.