Overlap Arrhythmia Syndromes Resulting from Multiple Genetic Variations Studied in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are used for genetic models of cardiac diseases. We report an arrhythmia syndrome consisting of Early Repolarization Syndrome (ERS) and Short QT Syndrome (SQTS). The index patient (MMRL1215) developed arrhythmia-mediated syncope after electrocution and was found to carry six mutations. Functional alterations resulting from these mutations were examined in patient-derived hiPSC-CMs. Electrophysiological recordings were made in hiPSC-CMs from MMRL1215 and healthy controls. ECG analysis of the index patient showed slurring of the QRS complex and QTc = 326 ms. Action potential (AP) recordings from MMRL1215 myocytes showed slower spontaneous activity and AP duration was shorter. Field potential recordings from MMRL1215 hiPSC-CMs lack a "pseudo" QRS complex suggesting reduced inward current(s). Voltage clamp analysis of ICa showed no difference in the magnitude of current. Measurements of INa reveal a 60% reduction in INa density in MMRL1215 hiPSC-CMs. Steady inactivation and recovery of INa was unaffected. mRNA analysis revealed ANK2 and SCN5A are significantly reduced in hiPSC-CM derived from MMRL1215, consistent with electrophysiological recordings. The polygenic cause of ERS/SQTS phenotype is likely due to a loss of INa due to a mutation in PKP2 coupled with and a gain of function in IK,ATP due to a mutation in ABCC9.

A perspective on global access to insulin: a descriptive study of the market, trade flows and prices

AIM

To describe the global insulin market.

METHODS

Market intelligence data, United Nations Commodity Trade Statistics for insulin trade, the International Medical Products Price Guide for prices of human insulin and additional web searches were used as data sources. These sources were combined to gain further insight into possible links among market, trade flows and prices. Descriptive statistics and Spearman's rank order correlation were used for the analysis.

RESULTS

A total of 34 insulin manufacturers were identified. Most countries and territories are reliant on a limited number of supplying countries. The overall median (interquartile range) government procurement price for a 10-ml, 100-IU/ml vial during the period 1996-2013 equivalent was US$4.3 (US$ 3.8-4.8), with median prices in Africa (US$ 4.7) and low- (US$ 6.9) and low- to middle- (US$ 4.7) income countries being higher over this period. The relationships between price and quantity of insulin (Spearman's r=0.046; P>0.1) and number of import links (Spearman's r=0.032; P>0.1) were weak. The links between price and percentage of total insulin from a country where a 'big three' manufacturer produces insulin (Spearman's r=0.294; P<0.05) and total insulin from the main import link (Spearman's r=-0.392; P<0.05) were stronger.

CONCLUSIONS

This research shows the high variability of insulin prices and the reliance on a few sources, both companies and countries, for global supply. In addressing access to insulin, countries need to use existing price data to negotiate prices, and mechanisms need to be developed to foster competition and security of supply of insulin, given the limited number of truly global producers.

Design and synthesis of a novel series of 4-heteroarylamino-1'-azaspiro[oxazole-5,3'-bicyclo[2.2.2]octanes as α7 nicotinic receptor agonists 2. Development of 4-heteroaryl SAR

Quinuclidine-containing spirooxazolines, as described in the previous report in this series, were demonstrated to have utility as α7 nicotinic acetylcholine receptor (α7 nAChR) partial agonists. In this work, the SAR of this chemotype was expanded to include an array of diazine heterocyclic substitutions. Many of the heterocyclic analogs were potent partial agonists of the α7 receptor, selective against other nicotinic receptors and the serotinergic 5HT_3A receptor. (1'S,3'R,4'S)-N-(6-phenylpyrimidin-4-yl)-4H-1'-azaspiro[oxazole-5,3'-bicyclo[2.2.2]octan]-2-amine, a potent and selective α7 nAChR partial agonist, was demonstrated to improve cognition in the mouse novel object recognition (NOR) model of episodic memory.

meso-Acetoxymethyl BODIPY dyes for photodynamic therapy: improved photostability of singlet oxygen photosensitizers

Br or I substituted BODIPY photosensitizers for photodynamic therapy bearmeso-acetoxymethyl substitutents for improved photostability to singlet-oxygen damage rendering enhanced¹O₂generation before photodestruction.

Effect of day of mixing gestating sows on measures of reproductive performance and animal welfare

Effects of day of mixing sows after breeding were measured for reproduction and welfare on a commercial research farm. Sows (n = 1,436) were weaned into stalls for breeding, and groups of sows were assigned to 1) no mixing and housed in individual stalls (STL), 2) mixed on d 3 to 7 after breeding (D3), 3) mixed on d 13 to 17 after breeding (D14), or 4) mixed 35 d after breeding (D35). Mixed sows were moved into pens (n = 58 sows/pen) with an electronic sow feeding station and maintained as a static group. In the first 12 d after mixing or movement into STL (period 1), sows were assessed for lameness and lesions every 3 d and then every 2 wk until farrowing (period 2). Cortisol and fights were measured in period 1. Conception rates were reduced (P < 0.005) in D3 (87.1%) and D14 (89.2%) compared to D35 (92.2%) and STL (96.2%). Farrowing rates were lower (P < 0.0001) in D3 (82.8%) compared to D35 (90.5%) and STL (96.2%), but litter size was not (P ≥ 0.20) affected by mixing. The proportion of sows bred within 10 d of weaning was reduced (P < 0.05) for D14 compared to STL, but D3 and D35 did not differ among treatments. Number of fights 24 h after mixing was less (P < 0.0001) for D14 compared to D3 and D35 groups, and serum cortisol was greater (P < 0.05) for D35 compared to STL and D3. From period 1 to 2, lameness increased in D3 and decreased in D35 but did not change for D14 and STL (treatment × period, P < 0.05), whereas leg inflammation did not differ (P > 0.10) among treatments. Head and body lesion scores declined from period 1 to 2 in all mix groups, whereas vulva lesions increased in the D3 and D35 but did not change in D14 and STL (treatment × period, P < 0.0001). These results suggest STL can improve most measures of welfare compared to mixing in groups. However, when mixing sows, assessments for reproductive performance and welfare may change from gestation to farrowing. The poorest reproductive performance and welfare was observed when sows were mixed 3 to 7 d after breeding. There were few differences between the D14 and D35 treatments in reproduction or welfare, but D14--not D35--differed from STL in weaned sows rebred. Overall, results of this trial suggest that, even though any of the mixing days can result in acceptable measures of reproduction, there are clear effects of day of mixing on fertility and welfare, and special attention should be focused on the long-term reproductive and welfare consequences.

Development of a high-throughput calcium flux assay for identification of all ligand types including positive, negative, and silent allosteric modulators for G protein-coupled receptors

In recent years, the increased use of cell-based functional assays for G protein-coupled receptors in high-throughput screening has enabled the design of robust assays to identify allosteric modulators (AMs) in addition to the more traditional orthosteric agonists and antagonists. In this article, the authors describe a screening format able to identify all ligand types using a triple-add assay that measures changes in cytosolic calcium concentration with three separate additions and reads in the same assay plate. This triple-add assay captures more small molecule ligand types than previously described assay formats without a significant increase in screening cost. Finally, the customizability of the triple-add assay to suit the needs of various AM screening programs is demonstrated.

Taking training into your own hands

The Young Diabetologists' Forum (YDF) is a group designed and run by specialist trainees in endocrinology and diabetes that aims to provide high quality educational events. The YDF recognised that not all trainees in the specialty had equitable access to training opportunities and resolved to try and remedy the situation. This article describes the history and evolution of the YDF into an organisation representing over 400 trainees in endocrinology and diabetes, providing up to seven training events per year and with a budget of over pounds 200,000. As well as offering education and training another key purpose of the YDF is to give trainees from around the country the opportunity to meet up and exchange thoughts and ideas. The overall aim of the organisation is to improve the lives of people with diabetes by helping to ensure that future specialists are fully equipped for their role.

41 DETERMINATION OF THE RELATIONSHIP BETWEEN VULVAR SKIN TEMPERATURES AND TIME OF OVULATION IN SWINE USING DIGITAL INFRARED THERMOGRAPHY

Accurate estrus detection is an essential component of a successful AI program in modern swine operations. It is necessary to establish efficacious means of estrus detection and optimize reproductive performance in the herd. Measurement of physiological traits such as body temperature, vaginal electrical resistance, and vulva reddening have been investigated as methods to aid in estrus detection in swine. The relationship between vulvar skin temperature (VST) and ovulation has not been previously investigated. Therefore, the objective of this study was to assess changes in VST that occur during the periovulatory period using digital infrared thermography (IRT). The experiment group consisted of a total of 25 gilts and 27 multiparous sows, and the control group consisted of 30 sows that were 60 days of gestation. All Yorkshire-Landrace females were housed individually in a temperature and humidity controlled environment. VST were measured twice daily at 8-h intervals using the infrared digital thermocamera (Fluke IR FlexCam® Thermal Imager, Fluke Corporation, Everett, WA) while the animals were standing and eating prior to estrus detection. Estrus detection was performed twice daily (at 8-h intervals) with the aid of an adult boar. Once standing estrus was observed, transrectal real-time ultrasound was performed twice daily at 8-h intervals to monitor follicle development and determine the time of ovulation. Ovaries were visualized using an Aloka 500 V ultrasonics machine (Aloka Inc., Tokyo, Japan) fitted with a transrectal 7.5-MHz linear transducer, which was fitted into a rigid, fixed-angle PVC adapter. Average VST and hours were reported in mean ± SEM and compared using an ANOVA and Student’s t-test using SAS software (SAS Institute Inc., Cary, NC, USA). Additionally, pairwise comparisons were performed to compare VST at different times during estrus. Significant differences were reported at P ≤ 0.05. Evidence of CL formation and ovulation was detected at 38 ± 9.3 h after onset of estrus in gilts, and 43 ± 12 h in sows. The mean VST of sows during estrus was significantly higher (P ≤ 0.05) than that of gilts. During estrus, the mean VST of gilts reached a peak of 35.6 ± 0.24°C and then decreased significantly to 33.9 ± 0.32°C 12 h prior to ovulation. This marked change in mean VST was detected between 36 and 12 h prior to ovulation. There was a similar trend in sows with a peak mean VST of 36.1 ± 0.25°C at 24 h prior to ovulation and then dropping to 34.6 ± 0.31°C 12 h prior to ovulation. There was no significant difference (P ≥ 0.05) between VST in gilts and sows at the time of ovulation. This study demonstrated that VST of sows and gilts measured by IRT change significantly during the periovulatory period. Additionally, there are distinct times that VST rises and then falls precipitously in sows compared with gilts. Digital IRT as a predictor for ovulation in swine appears to be a promising tool. Further studies involving predictor models and hormonal assays need to be performed.

Improvement in asthma symptoms and quality of life in pediatric patients through specialty care delivered via telemedicine

Asthma is the most common chronic disease affecting children. Studies have demonstrated improvements in asthma control when care is delivered by specialists compared with generalists. We postulated that specialist care delivered by telemedicine would result in similar improvements in control of symptoms and quality of life as compared with face-to-face encounters with specialists. Seventeen patients with persistent asthma, who were cared for by pediatricians in a rural school-based health clinic, were treated over a 6-month period in an asthma specialty program. Patients had face-to-face encounters at week zero, and then telemedicine follow-up visits at weeks 4, 12, and 24. Patients maintained a symptom diary and reliever medication use log. Spirometry and patient and caregiver quality-of-life questionnaires were completed at each visit. Mean number of symptom free days increased 83% from 2.35 days at week 0 to 4.31 days at week 24 (p < 0.05). There was a 44% reduction in mean symptom scores, from 2.32 at week 0 to 1.31 at week 24 (p < 0.001). Nine patients reported having 7 symptom-free days or 7 days of symptom scores of zero in the preceding seven days at week 24 compared with one patient at week 0 (p < 0.002). FEV(1) increased by > or = 12% in seven patients during the study period. Significant improvements in quality of life were reported by patients at week 4 (p < 0.02) and week 24 (p < 0.01), and by caregivers at week 24 (p < 0.002). Specialty asthma care delivered via telemedicine resulted in improvements in asthma symptom control and quality of life similar to improvements reported in face-to-face encounters provided by specialists.

Audiotapes of oncology consultations: only for the first consultation?

BACKGROUND

Patients value audiotapes of their oncology consultations and letters summarising the discussion, and report improved recall and satisfaction when they receive them. However, studies to date have provided these interventions only after the initial or 'bad news' consultation. This study aimed to evaluate the utility of audiotaping routine follow-up oncology consultations.

PATIENTS AND METHODS

This was a prospective study following a cohort of consecutive patients attending routine follow-up at oncology outpatient appointments with one oncologist. Patients were approached when they attended their appointment and offered the opportunity to be audiotaped. Acceptance rates and reasons for refusal were documented. Two weeks after the consultation, patients were telephoned regarding their response to the tape and were sent a letter summarising the consultation. Two weeks later they received a further telephone call regarding the letter and their perceptions of the comparative value of the two interventions.

RESULTS

Seventy-five per cent of patients were female and for 40% English was not their first language. The patients had attended a median of 14 previous oncology appointments; 52 patients were offered audiotaping, 43 accepted and 30 decided to take home a copy of the audiotape. One patient felt recording had limited the discussion. Patients refused the tape most commonly because they felt no need for this aid, and accepted it most commonly to aid recall or share with family. Twenty-six patients listened to the tape, 14 did so more than once. Twenty had shared it with another person and over 75% thought it was useful. The majority (57%) preferred to receive both the tape and letter, with three preferring the tape alone and seven the letter. Married patients and those receiving bad news were more likely to want the tape.

CONCLUSIONS

Audiotaping follow-up consultations is an inexpensive procedure that is appreciated by the majority of patients. Randomised controlled trials of their impact are warranted.

The integrin-mediated cyclic strain-induced signaling pathway in vascular endothelial cells

The irregular distribution of plaque in the vasculature results from the interaction of local hemodynamic forces with the vessel wall. One well-characterized force is cyclic circumferential strain, the repetitive pulsatile pressure distention on the arterial wall. This review summarizes current research, which has aimed to elicit the signal transduction pathway by which cyclic strain elicits functional and structural responses in endothelial cells; specifically, it summarizes the signaling pathway that begins with the reorganization of integrins. One method by which these extracellular matrix receptors affect signal transduction is through their ability to initiate the process of phosphorylation on tyrosine residues of cytoplasmic protein kinases, including focal adhesion kinase. The strain-induced pathway appears to also involve ras and the mitogen-activated protein kinase family of enzymes, and preliminary data suggests a role for src as well. Ultimately, it is the regulation of gene expression through the modulation of transcription factors that allows endothelial cells to respond to changes in local hemodynamics.

Demonstration of the Activation of Prodrug CB 1954 Using Human DT-Diaphorase Mutant Q104Y-Transfected MDA-MB-231 Cells and Mouse Xenograft Model

The rat form of DT-diaphorase (NAD(P)H: quinone acceptor oxidoreductase; EC 1.6.99.2) is more effective than the human form in activating prodrugs such as CB 1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide). Our site-directed mutagenesis study has revealed that residue 104 (Tyr in the rat enzyme and Gln in the human enzyme) is an important residue responsible for the catalytic differences between the rat and the human enzymes in the activation of CB 1954 (S. Chen et al., 1997, J. Biol. Chem. 272, 1437-1439). The human mutant Q104Y is capable of reducing CB 1954 at a rate identical to that of the wild-type rat DT-diaphorase. In the present study, we prepared both the wild-type human DT-diaphorase- and the mutant Q104Y-expressing MDA-MB-231 breast cancer cell lines using the cDNA transfection method. The MDA-MB-231 cell line is homozygous for a P187S mutation in the DT-diaphorase gene and has no detectable DT-diaphorase activity. Stable clones for the wild-type transfected cells had the DT-diaphorase activity ranged from 0.1 to 3.8 micromol of DCIP reduced/min/mg of protein and the clones for Q104Y transfected cells had the activity ranged from 0.06 to 1.58 micromol of DCIP reduced/min/mg of protein. Furthermore, in contrast to the cells transfected with only expression vector that were not sensitive to CB 1954 treatment, the wild-type and Q104Y-expressing cells were capable of the reductive activation of CB 1954, resulting in cell eradication. Our data showed that cell killing by CB 1954 followed a dose and incubation-time dependent manner. It was also found that the cell survival upon the treatment of CB 1954 was related to the expressed DT-diaphorase activity in these cells. In the presence of 75 microM CB 1954, a 50% cell killing was achieved in cells containing Q104Y and the wild-type DT-diaphorase with the activity at approximately 0.67 and 3.8 micromol of DCIP reduced/min/mg of protein, respectively. These results agree well with those of the in vitro enzyme assays that show that Q104Y is significantly more active than the wild-type DT-diaphorase in the activation of CB 1954. Finally, the in vivo activation of CB 1954 was demonstrated with a nude mouse model using Q104Y-transfected MDA-MB-231 cells. These studies reveal that DT-diaphorase can activate CB 1954, and human Q104Y mutant enzyme is more active than the wild-type enzyme in the intracellular reductive activation of CB 1954.

Structure-function studies of DT-diaphorase (NQO1) and NRH: quinone oxidoreductase (NQO2)

DT-diaphorase, also referred to as NQO1 or NAD(P)H: quinone acceptor oxidoreductase, is a flavoprotein that catalyzes the two-electron reduction of quinones and quinonoid compounds to hydroquinones, using either NADH or NADPH as the electron donor. NRH (dihydronicotinamide riboside): quinone oxidoreductase, also referred to as NQO2, has a high nucleotide sequence identity to DT-diaphorase and is considered to be an isozyme of DT-diaphorase. These enzymes transfer two electrons to a quinone, resulting in the formation of a hydroquinone product without the accumulation of a dissociated semiquinone. Steady and rapid-reaction kinetic experiments have been performed to determine the reaction mechanism of DT-diaphorase. Furthermore, chimeric and site-directed mutagenesis experiments have been performed to determine the molecular basis of the catalytic differences between the two isozymes and to identify the critical amino acid residues that interact with various inhibitors of the enzymes. In addition, functional studies of a natural occurring mutant Pro-187 to Ser (P187S) have been carried out. Results obtained from these investigations are summarized and discussed.

Telehealth in a rural school-based health center

Telehealth is a new technology for the delivery of health care that allows a provider to deliver health care to a client at a remote setting via full, real-time video and audio interaction (American Nurses' Association, 1996). Telehealth does not change traditional health care standards or practice. School-based health centers are designed specifically for children and offer a continuum of preventive and acute care interventions that few other health care entities can provide (School-Based Adolescent Health Care Program, 1993). Telehealth and a school-based health center were joined together in a pilot project to demonstrate the efficacy of primary care via telehealth and to determine the value of this technology to the school and community. The telehealth capability enhanced the role of the school nurse and increased access to primary care for the students. The students were quick to adapt to the technology. The role of the school nurse was essential to the success of this project.

Molecular characterization of binding of substrates and inhibitors to DT-diaphorase: combined approach involving site-directed mutagenesis, inhibitor-binding analysis, and computer modeling

The molecular basis of the interaction of DT-diaphorase with a cytotoxic nitrobenzamide CB1954 [5-(aziridin-1-yl)-2, 4-dinitrobenzamide] and five inhibitors was investigated with wild-type DT-diaphorase (human and rat) and five mutants [three rat mutants (rY128D, rG150V, rH194D) and two human mutants (hY155F, hH161Q)]. hY155F and hH161Q were generated to evaluate a hypothesis that Tyr155 and His161 participate in the obligatory two-electron transfer reaction of the enzyme. The catalytic properties of hY155F and hH161Q were compared with a naturally occurring mutant, hP187S. Pro187 to Ser mutation disturbs the structure of the central parallel beta-sheet, resulting in a reduction of the binding affinity of the flavin-adenine dinucleotide prosthetic group. With NADH as the electron donor and menadione as the electron acceptor, the k(cat) values for the wild-type human DT-diaphorase, hY155F, hH161Q, and hP187S were measured as 66 +/- 1, 23 +/- 0, 5 +/- 0 and 8 +/- 2 x 10(3) min(-1), respectively. Because hY155F still has significant catalytic activity, the hydroxyl group on Tyr155 may not be as important as proposed. Interestingly, hY155F was found to be 3. 3 times more active than the human wild-type DT-diaphorase in the reduction of CB1954. Computer modeling based on our results suggests that CB1954 is situated in the active site, with the aziridinyl group pointing toward Tyr155 and the amide group placed near a hydrophobic pocket next to Tyr128. Dicoumarol, Cibacron blue, chrysin, 7,8-dihydroxyflavone, and phenindone are competitive inhibitors of the enzyme with respect to nicotinamide coenzymes. The binding orientations of dicoumarol, flavones, and phenindone in the active site of DT-diaphorase were predicted by results from our inhibitor-binding studies and computer modeling based on published X-ray structures. Our studies generated results that explain why dicoumarol is a potent inhibitor and binds differently from flavones and phenindone in the active site of DT-diaphorase.

Immune dysfunction and the pathogenesis of AIDS-associated non-Hodgkin's lymphoma

Much has been learned about how HIV-induced immune dysfunction contributes to B cell hyperactivation, and potentially, to the pathogenesis of AIDS-lymphoma. However, further studies are needed to fully understand how HIV infection and immune dysfunction promote B cell hyperactivation and the development/growth of AIDS-lymphoma. In particular, studies are needed to define the role of HHV8 vIL6, IL6 receptor-expression, and lymphocyte surface stimulatory molecules, in promoting B cell hyperactivation or lymphoma cell growth.

Catalytic properties of NAD(P)H:quinone oxidoreductase-2 (NQO2), a dihydronicotinamide riboside dependent oxidoreductase

Human NAD(P)H:quinone acceptor oxidoreductase-2 (NQO2) has been prepared using an Escherichia coli expression method. NQO2 is thought to be an isoform of DT-diaphorase (EC 1.6.99.2) [also referred to as NAD(P)H:quinone acceptor oxidoreductase] because there is a 49% identity between their amino acid sequences. The present investigation has revealed that like DT-diaphorase, NQO2 is a dimer enzyme with one FAD prosthetic group per subunit. Interestingly, NQO2 uses dihydronicotinamide riboside (NRH) rather than NAD(P)H as an electron donor. It catalyzes a two-electron reduction of quinones and oxidation-reduction dyes. One-electron acceptors, such as potassium ferricyanide, cannot be reduced by NQO2. This enzyme also catalyzes a four-electron reduction, using methyl red as the electron acceptor. The NRH-methyl red reductase activity of NQO2 is 11 times the NADH-methyl red reductase activity of DT-diaphorase. In addition, through a four-electron reduction reaction, NQO2 can catalyze nitroreduction of cytotoxic compound CB 1954 [5-(aziridin-1-yl)-2,4-dinitrobenzamide]. NQO2 is 3000 times more effective than DT-diaphorase in the reduction of CB 1954. Therefore, NQO2 is a NRH-dependent oxidoreductase which catalyzes two- and four-electron reduction reactions. NQO2 is resistant to typical inhibitors of DT-diaphorase, such as dicumarol, Cibacron blue, and phenindone. Flavones are inhibitors of NQO2. However, structural requirements of flavones for the inhibition of NQO2 are different from those for DT-diaphorase. The most potent flavone inhibitor tested so far is quercetin (3,5,7,3',4'-. 6pentahydroxyflavone). It has been found that quercetin is a competitive inhibitor with respect to NRH (Ki = 21 nM). NQO2 is 43 amino acids shorter than DT-diaphorase, and it has been suggested that the carboxyl terminus of DT-diaphorase plays a role in substrate binding (S. Chen et al., Protein Sci. 3, 51-57, 1994). In order to understand better the basis of catalytic differences between NQO2 and DT-diaphorase, a human NQO2 with 43 amino acids from the carboxyl terminus of human DT-diaphorase (i.e., hNQO2-hDT43) has been prepared. hNQO2-hDT43 still uses NRH as an electron donor. In addition, the chimeric enzyme is inhibited by quercetin but not dicumarol. These results suggest that additional region(s) in these enzymes is involved in differentiating NRH from NAD(P)H.

Selective cell ablation in transgenic mice expression E. coli nitroreductase

The gene encoding E. coli nitroreductase (NTR) was expressed in the luminal cells of the mammary gland of transgenic mice using the ovine beta-lactoglobulin promoter. Treatment of NTR expressing animals with the prodrug CB1954 (5-aziridin-1-yl-2-4-dinitrobenzamide) resulted in a rapid and selective killing of this population of cells whereas the closely associated myoepithelial cells were unaffected. NTR-mediated inducible cell ablation offers a number of advantages over the use of HSV1-tk for the selective killing of cells in vivo.

Molecular basis of the catalytic differences among DT-diaphorase of human, rat, and mouse

DT-diaphorase (EC 1.6.99.2), also referred to as NAD(P)H:(quinone-acceptor) oxidoreductase, is involved in the reductive activation process of several cytotoxic antitumor quinones and nitrobenzenes. It has been observed in our and other laboratories that the rat enzyme is significantly more effective in activating these drugs than the human and mouse enzymes. These results indicate that the available cytotoxic drugs are better substrates for the rat enzyme and are not the most ideal prodrugs for activation by DT-diaphorase in human tumors. In this study, using site-directed mutagenesis to replace residues in the rat enzyme with the human sequences and residues in the human enzyme with the rat sequences, we have found that residue 104 (Tyr in the rat enzyme and Gln in the human and mouse enzymes) is an important residue responsible for the catalytic differences between the rat and the human (and mouse) enzymes. With an exchange of a single amino acid, the rat mutant Y104Q behaved like the wild-type human enzyme, and the human mutant Q104Y behaved like the wild-type rat enzyme in their ability to reductively activate the cytotoxic drug CB 1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide). The study also confirms the conclusion of the x-ray structural analysis of rat enzyme that residue 130 (Thr in the rat enzyme and Ala in the human and mouse enzymes) is positioned near the binding region of the nicotinamide portion of NAD(P)H. This structural information is very important for designing suitable drugs and approaches for human cancer chemotherapy mediated by DT-diaphorase.

Catalytic properties of NAD(P)H:quinone acceptor oxidoreductase: study involving mouse, rat, human, and mouse-rat chimeric enzymes

NAD(P):quinone acceptor oxidoreductase (quinone reductase) (DT-diaphorase, EC 1.6.99.2) is involved in the process of reductive activation of cytotoxic antitumor quinones and nitrobenzenes. In this study, we initially examined the relative abilities of mouse, rat, and human quinone reductases to reduce two prodrugs, CB 1954 [5-(aziridin-1-yl)-2,4-dinitrobenzamide] and EO9 [5-(1-aziridinyl)-3-(hydroxymethyl)-2-(3-hydroxy-1-propenyl)-1- methyl-1H-indole-4,7-dione]. By using Escherichia coli-expressed quinone reductases and evaluating them under identical conditions, we confirmed previous finding showing that the human enzyme is not as effective as the rat enzyme in reducing CB 1954 and EO9, although the two enzymes have similar NAD(P)H-menadione reductase activities. Interestingly, although the amino acid sequence of mouse quinone reductase is more homologous to that of the rat enzyme, we found that the mouse enzyme behaves similarly to the human enzyme in its ability to reduce these compounds and to generate drug-induced DNA damage. To determine the region of quinone reductase that is responsible for the catalytic differences, two mouse-rat chimeric enzymes were generated. MR-P, a chimeric enzyme that has mouse amino-terminal and rat carboxy-terminal segments of quinone reductase, was shown to have catalytic properties resembling those of rat quinone reductase, and RM-P, a chimeric enzyme that has rat amino-terminal and mouse carboxyl-terminal segments of quinone reductase, was shown to have catalytic properties resembling those of mouse quinone reductase. In addition, MR-P and RM-P were found to be inhibited by flavones with Ki values similar to those for rat and mouse quinone reductases, respectively. Based on these results, we propose that the carboxyl-terminal portion of the enzyme plays an important role in the reduction of cytotoxic drugs and the binding of flavones.

A five-year experience with severe injuries in elderly patients

Recent reports of injury in elderly patients document that aggressive care is justified. Our experience indicates that geriatric injury differs from that of other trauma patients. All patients entered into a large urban trauma center registry over a five-year period were analyzed. Variables reviewed included demographics, trauma indices, mechanism of injury, mean number of hospital days, and morbidity and mortality for patients under 60 years old and for geriatric patients defined as those aged 60 and above. There were 3,064 patients in the reviewed group, of whom 243 qualified for geriatric analysis. Blunt injuries in males were the most typical scenario. Failure to use safety belts and alcohol intoxication persist into the geriatric age group (83% and 13%, respectively). Trauma indices including Injury Severity Score (ISS) were slightly greater in the geriatric group (27 versus 23) as compared to younger patients; plus geriatric patients tolerated head injury less well (GCS in those who died 6.7 versus 4.6, respectively; p < 0.001). Mortality in the geriatric group was 31% while being 17.1% in the younger group (p < 0.005). Days in the hospital were 20 for the geriatric compared to 13 for the younger group (p < 0.025). Infections and chest complications were twice as common in the elderly and dysrhythmias were five times more frequent. Elderly patients constitute 8% of the trauma population and suffer a magnitude of injury at least comparable to the general population. Their mortality is approximately 50% above the population as a whole and morbidity twice as common, accounting for the prolonged hospital stay.

Fibrinogen and the albumin-globulin ratio in recurrent stroke

BACKGROUND AND PURPOSE

In following patients initially recruited for a cross-sectional study of blood viscosity in ischemic cerebrovascular disease, it was noted that those having a low albumin-globulin ratio appeared to experience the majority of subsequent vascular events. Accordingly, a prospective study in which subjects were assigned to a high or low albumin-globulin cohort was undertaken to examine the relation between a low albumin-globulin ratio, the presence of clinical risk factors for stroke, and the occurrence of subsequent stroke, myocardial infarction, or vascular death.

METHODS

Three groups of subjects were followed for an average of 1.5 +/- 0.8 years to ascertain vascular end points. Group 1 consisted of 126 patients with acute ischemic stroke; group 2 included 109 subjects matched with group 1 for age, medications, and recognized clinical risk factors for stroke; and group 3 was composed of 84 healthy volunteers, matched for age with groups 1 and 2. The median albumin-globulin ratio for group 1 at enrollment, 1.45, was used to dichotomize patients into two cohorts: all subjects with an albumin-globulin ratio of 1.45 or less were assigned to the "low" albumin-globulin cohort; those whose ratio was greater than 1.45 were assigned to the "high" albumin-globulin cohort. The occurrence of vascular end points was verified during subsequent hospitalizations and outpatient clinic visits and by telephone interviews of patients and providers.

RESULTS

A total of 51 vascular events occurred, including 39 in group 1, 8 in group 2, and 4 in group 3. Subjects in either group 1 or 2 who were in the low albumin-globulin cohort had at least double the risk for a subsequent vascular event compared with their counterparts in the high albumin-globulin cohort (P < .01 and P < .03, respectively). In comparison with the high albumin-globulin cohort, significantly more patients in the low albumin-globulin cohort in group 1 had a history of prior stroke (P < .03). When groups 1 and 2 were combined, both a low albumin-globulin ratio and diabetes had a significant independent association with increased risk for subsequent vascular events in a Cox proportional-hazards model (P < .01 and P < .03, respectively).

CONCLUSIONS

The results of this study indicate that significantly increased risk for subsequent vascular events in stroke patients and in subjects with clinical risk factors for stroke is associated with a shift in the concentrations of blood proteins to a prothrombotic environment characterized by lower levels of albumin and an increased concentration of globulins and fibrinogen.

Steroid use is associated with pneumonia in pediatric chest trauma

A review of pediatric trauma focused on pediatric chest injuries was performed at a trauma center specializing in neurologic trauma. Eighty of 342 (23%) pediatric trauma patients admitted to the center had chest injuries. Age, gender, mechanism of injury, magnitude of injury, incidence of pulmonary infection, chest tube usage, endotracheal intubation, steroid or antibiotic usage, morbidity, and mortality data were reviewed. Sixteen of 78 children (20%) with chest injuries developed pulmonary infections and were compared with the noninfected group. Patients with pneumonia had a higher morbidity with significantly longer mean hospital stay (43.0 vs. 12.7 days; p = 0.001), duration of intubation (8.4 vs. 1.5 days; p = 0.001), and total days with chest tubes, (2.2 vs. 1.4 days; p = 0.02). Pneumonia was significantly associated with longer mean duration of steroid usage (6.4 vs. 0.8 days; p = 0.0001). Duration of steroid administration for the treatment of concomitant brain injury was a significant independent risk factor for the occurrence of pneumonia.

Effect of fat pre-feeding on bile flow and composition in the rat

Studies were conducted in rats to determine if the increase in lymph triacylglycerol output on pre-feeding a 20% glyceryltrioleate diet (Mansbach, C.M., II and Arnold, A. (1986) Am. J. Physiol. 251, G263-269) was due to an increase in phosphatidylcholine output into bile. Rats who were fed chow or pre-fed the 20% fat diet were equipped with biliary and duodenal cannulas and infused with glucose-saline while bile was collected hourly. The next day a taurocholate-glyceryltrioleate infusion was given and bile collected for 5 h. Bile flow, bile acid, phosphatidylcholine and cholesterol output were greater in the chow fed group than controls during the 6 h of the glucose saline period. Outputs were low overnight. During the taurocholate-glyceryltrioleate infusion, bile flow, bile acid, phosphatidylcholine and cholesterol output were all greater in the fat pre-fed group than the chow fed controls. We conclude that fat pre-feeding profoundly influences biliary composition and flow. The 2-fold increase in biliary phosphatidylcholine output during duodenal lipid infusion offers a potential explanation for the increased delivery of triacylglycerol into the lymph in rats on a similar fat pre-feeding program.

Chronic blood hyperviscosity in subjects with acute stroke, transient ischemic attack, and risk factors for stroke

The origin and significance of blood hyperviscosity in subjects with acute stroke has been controversial. It has been argued that viscous abnormalities simply reflect either elevated hematocrit or an acute-phase response to the stroke itself. To address these issues, we measured the factors that determine blood viscosity in a cross-sectional study of 430 subjects, including 135 with acute stroke, 89 with acute transient ischemic attacks of the brain, 115 with recognized risk factors for stroke, and 91 healthy controls. The at-risk group was balanced with the acute stroke group for types of risk factors and medication usage, and all four groups were balanced for age. The viscosity of whole blood at low rates of shear and the plasma viscosity were significantly elevated in both groups with cerebrovascular symptoms and in the at-risk group compared with the healthy controls. The severity of hyperviscosity was stroke group greater than transient ischemic attack group greater than at-risk group greater than healthy controls. Increased viscosity of whole blood was associated with an elevated plasma fibrinogen concentration and with a decreased albumin/globulin ratio. This study provides evidence that blood hyperviscosity is present not only in subjects with acute brain infarction, but also in those with risk factors for stroke, and that these abnormalities are, to a considerable degree, chronic.

Heterotopic lingual brain in the newborn

Heterotopic brain is a rare entity. Histologically, this lesion resembles mature brain and often contains specialized tissues similar to choroid plexus or glia. Specialized neural stains are necessary to differentiate this rare anomaly from other tumors or conditions found in the head and neck. The differential diagnosis includes squamous cell carcinoma, granular cell tumor, hemangioma, lymphangioma, thyroglossal duct cyst, dermoid cyst, hamartoma, rhabdomyosarcoma, and teratoma. We describe a newborn with heterotopic brain tissue occurring on the dorsum of the tongue. We found only one other description of this developmental aberration in the English literature. Our patient was successfully treated with carbon dioxide laser excision of the mass. There has been no evidence of complication or recurrence after one year of follow-up.