Elimination of the acetaminophen interference in an implantable glucose sensor

Acetaminophen has been one of the most serious electrochemical interferences to oxidase-based amperometric biosensors that measure H2O2. A study was carried out to investigate various polymer materials for their selectivity as the sensor inner membrane. A composite membrane of cellulose acetate and Nafion was found to eliminate acetaminophen and other electrochemical interferences effectively while at the same time maintaining reasonable diffusivity for hydrogen peroxide. The excellent in vivo performance of the sensor was attributed not only to significantly reduced steady-state sensitivity to acetaminophen but also to very slow acetaminophen response. These features, combined with rapid acetaminophen clearance pharmacokinetics, led to the decreased response as demonstrated in the rat.

Downregulation of beta-adrenergic receptors and signal transduction response in salivary glands of NOD mice

The nonobese diabetic (NOD) mouse is subject to autoimmune disease-associated lymphocytic attack on the salivary glands with a corresponding loss of exocrine function. Downregulation of stimulus response to the beta-adrenoceptor agonist, isoproterenol, appears to be related to a decline in beta-adrenergic receptor density, changes in the level of intracellular second messenger signaling component adenosine 3',5'-cyclic monophosphate, and protein kinase A activity. An autoantibody to the beta 1-adrenergic receptor present in the sera of diabetic NOD mice may be involved in the reduced agonist response by virtue of its ability to retard dihydroalprenolol radioligand binding to receptors in the membranes of salivary glands from control mice and recognition of purified beta 1-adrenergic receptor by immunoblotting techniques.

[Recurrent astrocytoma versus primary astrocytoma: a comparative study of morphological changes of 32 cases]

The pathologic morphological changes of 32 cases of recurrent astrocytoma (RA) and primary astrocytoma were reported. During recurrence, 20 cases (62.5%) of astrocytomas transformed into cases at higher grades. Twelve cases remained at the same grades as primary tumors. Among 21 cases of RA at grades III and IV, 15 cases (71.4%) came from primary astrocytomas, grades I and II. The change from astrocytoma grade I to grade III or IV took time longer than that from grade II to grade III or IV. The recurrent time of astrocytomas with different grades showed no statistical differences. Postoperative radiotherapy/chemotherapy did not play a major role in grading changes and recurrent time.

[Experimental study on the role of oxygen-free radicals in ischemic reperfusion tissue injury is island skin flaps]

In this study the role of oxygen-free radicals and the effect of treatment with superoxide dismutase (SOD) had been investigated in a 3 x 6 cm2 abdominal area island skin flaps of rat model which were subjected to 8 hours of total venous occlusion. In experiment 1, 56 rats were divided into seven test groups. Tissue assay for Malonydialdehyde (MDA) were obtained. Flaps with ischemia had higher MDA at 8.12 hours and all reperfusion groups had higher MDA as compared to the control groups (P < 0.01). In reperfusion groups, the MDA had increased at 4.8 hours compared to ischemia group at the same time. In experimental 2, 28 rats were used. Treatment with superoxide dismutase injected into the artery following the onset of reperfusion significantly enhanced island flap survival from 28.6% (4/14) to 78.6% (11/14) (P < 0.01).

[The effects of hypertonic and balanced saline solutions on burn shock resuscitation in burned rats]

Hypertonic saline solution (HS) has been used effectively to treat different kinds of shock. In this experiment, all rats are inflicted with a full-thickness burn of 20% BSA, and they are divided into three groups. Group I, control; group II, resuscitated with balanced saline solution; group III, with HS. All animals are sacrificed at 24 hours postburn to determine blood viscosity (BV) and tissue water content (TWC), as well as to observe the microcirculation in kidney with electronmicroscopy. We find that the TWC increased significantly in group II (P < 0.05), while BV decreased, especially in group III (P < 0.01). The electronmicroscopic observation indicates that: In group I, there are capillary dilatation, red cell aggregation, endothelium edema, and appearance of many gaps between endothelium. In group II, the blood flows easily and smoothly. In group III, the improvement of microcirculation is not significant and the blood vessel is filled with microthromboli. The results show that HS can improve systemic circulation, but not microcirculation.

The combination of coculture and selective assisted hatching: results from their clinical application

OBJECTIVE

To establish pregnancies using a combination of coculture and selective assisted hatching.

DESIGN

Clinical application for a selected group of patients. Not a controlled study.

SETTING

Private infertility practice.

PATIENTS

Women with high basal FSH levels, ovulatory disorders, and multiple failed IVF attempts.

MAIN OUTCOME MEASURES

Pregnancy and implantation rates.

RESULTS

Of the 95 patients who had coculture and selective assisted hatching, 45 (47.0%) have an ongoing pregnancy with a 23.0% implantation rate.

CONCLUSION

The combination of coculture and assisted hatching produced acceptable pregnancy and implantation rates within the selected patient population.

Genetic polymorphism of cytochrome P450. Functional consequences and possible relationship to disease and alcohol toxicity

The hepatic cytochrome P450 system participates in the oxidative metabolism of numerous endogenous and exogenous compounds. In total several hundred different P450s have been cloned, but it appears that in humans only about 5-10 isoforms account for the major part of drug metabolism. Some of these are polymorphically distributed in the population. Cytochrome P450 2D6 catalyzes the oxidation of over 25 clinically important drugs, eg neuroleptics, antidepressants and lipophilic beta-blockers. Seven % of Caucasians and 1% of Orientals are defective in this enzyme and clearance of drugs metabolized by the enzyme may be substantially decreased in these individuals, with potentially increased risks for side effects caused by the drug treatment. Some individuals are ultrarapid metabolizers and do not achieve therapeutic drug levels at ordinary doses. The molecular genetic basis of these polymorphisms are presented. Methods for genotyping, which can be of predictive value for a more efficient drug therapy, are discussed. Ethanol-inducible cytochrome P450 2E1 (CYP2E1) oxidizes ethanol and acetaldehyde, in addition to over 80 toxicologically important xenobiotics. Furthermore, this isozyme produces reactive oxy radicals which are implicated in the aetiology of alcoholic liver disease. The gene is polymorphic and a mutation in a putative binding site for HNF1, described to affect gene expression, is more rare among subjects with lung cancer as compared to healthy controls. Further studies might give an answer as to whether any of the polymorphic CYP2E1 alleles is associated with the sensitivity to obtain alcoholic liver disease.

Restrictive fragment length polymorphisms of markers 3'HVR and 24-1 and their applications in gene diagnosis of adult polycystic disease in Chinese

Adult polycystic kidney disease was diagnosed with pedigree analysis using polymorphic DNA markers linked to the disease gene in 5 families. The markers were thoroughly characterized in the population. We noted two important markers, 3'HVR and 24-1, which flank the disease gene PKD1 in normal Chinese. Southern hybridization was used, and numerous 3'HVR/PvuII polymorphic allelic bands varied from 1.4 kb to 8.0 kb with a positive skew distribution. They were divided into 11 groups with an interval of 0.6 kb and a heterozygosity rate of 0.86. Allele frequencies were observed. When the probe 24-1 was hybridized with genomic DNA digested by TaqI, two alleles, B1 and B2, were detected with frequencies of 0.76 and 0.24, respectively. B1 was 3.8 kb in size and B2 was composed of 2 bands, 1.5 kb and 1.3 kb. The polymorphism information content was found to be 0.297. Using these two markers for linkage analyses of 5 affected families, we confirmed the linkage between 3'HVR and the disease gene PKD1 and made presymptomatic diagnosis of the members at risk.

The nonstructural glycoprotein of rotavirus affects intracellular calcium levels

Rotavirus infection of monkey kidney cells has been reported to result in a significant increase in the concentration of intracellular calcium. This increase in intracellular calcium was associated with viral protein synthesis and cytopathic effects in infected cells. We tested the effect of individual rotavirus proteins on intracellular calcium concentrations in insect Spodoptera frugiperda (Sf9) cells. Insect cells were infected with wild-type baculovirus or baculovirus recombinants that contained an individual rotavirus gene. The cells were harvested at different times postinfection, and the intracellular calcium concentration was measured by using fura-2 as a fluorescent calcium indicator. We found that the concentration of intracellular calcium was increased nearly fivefold in infected Sf9 cells that expressed the nonstructural glycoprotein (NSP4) of group A rotavirus, and this increase in intracellular calcium concentration coincided with NSP4 expression. A similar result was observed in insect cells expressing NSP4 from a group B rotavirus, suggesting the conservation of this function among rotavirus groups. Expression of the other 10 rotavirus proteins or of wild-type baculovirus proteins in Sf9 cells did not significantly increase intracellular calcium levels. These results suggest that the nonstructural glycoprotein NSP4 is responsible for the increase in cytosolic calcium observed in rotavirus-infected cells.

Isolation and characterization of the murine homeobox gene Cdx-1. Regulation of expression in intestinal epithelial cells

The murine homeobox gene Cdx-1 is postulated to play an important role in the process of cellular commitment in the intestinal epithelium based upon its graded, tissue-specific expression pattern in the adult animal. We have isolated and sequenced both cDNA and genomic clones in order to understand how this expression pattern is regulated and to determine the amino acid sequence of the encoded protein. Our studies show that the Cdx-1 gene contains 3 exons and 2 introns and encodes a 268-amino acid protein which is translated from a 1.7-1.8-kilobase mRNA. Transcription of the Cdx-1 gene initiates some 30 base pairs downstream from a typical TATA box which, together with the 5' end of the gene, is located within a CpG island. Transient transfection experiments have shown three regions which regulate Cdx-1 gene expression. These include a typical silencer element at -589 to -380, an element at -887 to -1040 which blocks the effect of the silencer and a positive element at -47 to +66; the only one which shows epithelial cell specificity. Using gel shift and footprinting assays we have detected proteins in nuclear extracts prepared from colonic epithelial cells which bind to the silencer element. These initial results suggest that Cdx-1 gene expression is regulated by multiple positive and negative transcription factors.

Fast events in protein folding initiated by nanosecond laser photolysis

Initiation of protein folding by light can dramatically improve the time resolution of kinetic studies. Here we present an example of an optically triggered folding reaction by using nanosecond photodissociation of the heme-carbon monoxide complex of reduced cytochrome c. The optical trigger is based on the observation that under destabilizing conditions cytochrome c can be unfolded by preferential binding of carbon monoxide to the covalently attached heme group in the unfolded state. Photodissociation of the carbon monoxide thus triggers the folding reaction. We used time-resolved absorption spectroscopy to monitor binding at the heme. Before folding begins we observe transient binding of both nonnative and native ligands from the unfolded polypeptide on a microsecond time scale. Kinetic modeling suggests that the intramolecular binding of methionine-65 and -80 is faster than that of histidine-26 and -33, even though the histidines are closer to the heme. This optical trigger should provide a powerful method for studying chain collapse and secondary structure formation in cytochrome c without any limitations in time resolution.

[Studies on the correlation of blood selenium and lung cancer. II. An analysis of serum selenium levels and influencing factors in patients with lung cancer]

This paper reports the serum selenium concentration in 100 cases of lung cancer patients and 100 healthy controls. The results showed that the serum selenium level in patients with lung cancer was significantly lower than that of controls. Serum selenium level in lung cancer patients was inversely related to the stage of cancer, the amount of tobacco abuse and the serum Cu level. It was positively correlated with patient's nutritional status and the serum albumin level. Serum selenium level was decreased with cancer progression and increased with disease remission. These results suggest that the lower serum selenium level in lung cancer patients was the result rather than the cause of cancer.

Neurosteroid analogues: structure-activity studies of benz[e]indene modulators of GABAA receptor function. 1. The effect of 6-methyl substitution on the electrophysiological activity of 7-substituted benz[e]indene-3-carbonitriles

The effect of 6-methyl substitution of the ability of 7-(2-hydroxyethyl)benz[e]indene-3-carbonitriles to potentiate GABA-mediated chloride current and to directly gate a chloride current in the absence of GABA in cultured rat hippocampal neurons was investigated. Structurally analogous steroid 17-carbonitriles that either contained or did not contain a 19-methyl group were also investigated. Compounds were evaluated at 1 microM for their ability to potentiate GABA-mediated currents and at 10 microM for current activation in the absence of GABA. The benz[e]indene 3(R)-carbonitriles and analogous steroid 17 alpha-carbonitriles had no effects in either assay. The benz[e]indene-3(S)-carbonitriles and analogous steroid 17 alpha-carbonitriles were active in both assays. Relative to the 6-unsubstituted benz[e]indene 3(S)-carbonitrile, the following effects of 6-methyl substituents were observed: a 6(a)-methyl group increased both activities; a 6(e)-methyl group decreased both activities; and 6,6-dimethyl substituents had opposing effects so that both activities remained similar to those of the 6-unsubstituted compound. The activities of the steroid 17 beta-carbonitriles were not affected significantly by the presence or absence of a 19-methyl group. A conformational analysis using molecular modeling methods was also performed for the benz[e]indene 3S-carbonitriles and the steroid 17 beta-carbonitriles. The ability of the different 6-methyl substituents to differentially effect the conformations of the flexible benz[e]indenes and the inability of the steroid 19-methyl group to alter the conformations of the rigid steroid 17 beta-carbonitriles are suggested to explain the results.

Isolation and characterization of the binding sequences for the product of the Arabidopsis floral homeotic gene AGAMOUS

The Arabidopsis floral homeotic gene AGAMOUS (AG) is required for normal flower development. The deduced AG protein contains a region which shares substantial sequence similarity with the DNA-binding domains of known transcription factors, SRF (human) and MCM1 (yeast). Therefore, it is likely that AG is also a DNA-binding protein regulating transcription of floral genes. We describe here several experiments to characterize AG-DNA binding in vitro. We show that AG indeed binds a DNA sequence matching the consensus of SRF targets. Further, we have selected the AG-binding sequences from a pool of random oligonucleotides, and deduced an AG-binding consensus sequence of TT(A/T)CC(A/T)(A/t)2(T/A)NNGG(-G)(A/t)2. We have demonstrated that AG binds to the consensus region of three of the oligonucleotides by footprinting analysis. Finally, we have examined AG's relative binding affinity for different sequences, as compared to SRF, by gel mobility shift analysis. Our results indicate that AG is a sequence-specific DNA-binding protein, and that the AG-binding consensus sequence is similar to those of MCM1 and SRF.

2-Aminopurine inhibits the double-stranded RNA-dependent protein kinase both in vitro and in vivo

The autophosphorylation of interferon (IFN)-induced double-stranded RNA-dependent p68 protein kinase (PKR) and phosphorylation of the alpha-subunit of the translation initiation factor eIF-2 were inhibited by 10 mM 2-aminopurine in vitro. High concentrations of ATP overcame the inhibition. Kinetic studies indicated that 2-aminopurine is a competitive inhibitor with respect to ATP, suggesting that these two molecules bind the same site on the kinase. Treatment of HeLa cells with poly(I):poly(C) stimulated PKR autophosphorylation in vivo. The stimulated activity was inhibited by 10 mM 2-aminopurine to approximately the same extent as the in vitro inhibition.

MyoD and regulation of prostaglandin H synthase

MM14 myoblasts, in contrast to their differentiation defective variant (DD-1) cells, do not synthesize detectable levels of prostaglandins or of the initial enzyme in the pathway of prostaglandin synthesis, prostaglandin H synthase (PGHS) but do exhibit readily detectable level of PGHS mRNA (Steiner, S., et al., 1991, Exp. Cell Res. 192, 643). These findings suggest a possible relationship between the myogenic phenotype and the synthesis of prostaglandins. This relationship was examined in the current study by analysis of the effect of transfection of DD-1 cells with a MyoD expression vector (termed MyoDD-1 cells) on expression of MyoD and synthesis of prostaglandins. Proliferating MyoDD-1 cells express readily detectable levels of MyoD protein and mRNA and exhibit markedly diminished levels of PGHS protein and prostaglandins. In contrast, serum-deprived MyoDD-1 cells express little MyoD mRNA or protein and exhibit a readily detectable level of PGHS protein despite having only a slightly higher PGHS mRNA abundance compared to growing MyoDD-1 cells. These studies are consistent with the hypothesis that MyoD expression contributes to the inhibition of prostaglandin synthesis.