Dose-dependent pharmacokinetics of a new reversible proton pump inhibitor, DBM-819, after intravenous and oral administration to rats: hepatic first-pass effect

The dose-dependent pharmacokinetic parameters of DBM-819 were evaluated after intravenous (5, 10 and 20 mg/kg) and oral (10, 20 and 50 mg/kg) administrations of the drug to rats. The hepatic first-pass effect was also measured after intravenous and intraportal administrations of the drug, 10 mg/kg, to rats. After intravenous administration, the dose-normalized (based on 5 mg/kg) area under the plasma concentration-time curve from time zero to time infinity, AUC, at 20 mg/kg (27.0 and 45.8 microg min/ml) was significantly greater than that at 5 mg/kg due to saturable metabolism. After oral administration, the dose-normalized (based on 10 mg/kg) AUC(0-12 h) at 50 mg/kg (25.1, 18.3 and 49.2 microg min/ml) was significantly greater than those at 10 and 20 mg/kg again due to saturable metabolism. After oral administration of DBM-819, 10 mg/kg, 2.86% of oral dose was not absorbed and the extent of absolute oral bioavailability (F) was estimated to be 46.7%. After intraportal administration of DBM-819, 10 mg/kg, the AUC was 51.9% of intravenous administration, suggesting that approximately 48.1% was eliminated by liver (hepatic first-pass effect). The considerable hepatic first-pass effect of DBM-819 was also supported by significantly greater AUC of M3 (3.70 and 6.86 microg min/ml), a metabolite of DBM-819, after intraportal administration. The AUCs of DBM-819 were not significantly different (comparable) between intraportal and oral administrations of the drug, 10 mg/kg, suggesting that gastrointestinal first-pass effect of DBM-819 was almost negligible in rats. At 10 mg/kg oral dose of DBM-819, the hepatic first-pass effect was approximately 48.1%, F was approximately 46.7 and 2.86% was not absorbed from gastrointestinal tract in rats.

Mutations at the APC exon 15 in the colorectal neoplastic tissues of serial array

Although the APC protein is known to participate in cellular proliferation and apoptosis, APC mutations have been thought to play a major role in the early stage of colorectal tumorigenesis. The somatic APC mutation of exon 15 was assessed to determine its impact on various stages of colorectal tumorigenesis. The colorectal neoplastic tissues of serial array studied included sporadic adenomas (group 1, n = 36), adenomas (group 2, n = 33), and carcinomas (group 3, n = 32) in the synchronous adenoma and carcinoma as well as sporadic carcinomas (group 4, n = 36). Aberrant DNA was detected by protein truncation test and confirmed by direct sequencing. The mutation prevalence was 36.1% in group 1, 45.5% in group 2, 59.4% in group 3, and 41.7% in group 4 with no differences among the groups. Among the 18 patients with synchronous adenoma and carcinoma, 9 had mutation in their adenomas and 12 in their carcinomas. The mutation loci and patterns did not differ in adenomas and carcinomas. Mutations in the mutation cluster region (MCR) were much more frequent than in the preceding region of MCR, i.e., 85.7% vs. 14.3%. The mutation prevalence of villous adenomas appeared greater than that of tubular adenoma (3/21 vs. 3/4). Predominant pathogenic mutations at MCR suggest that the APC mutation is implicated in all stages of colorectal tumorigenesis.

Balloon dacryocystoplasty: results and factors influencing outcome in 350 patients

PURPOSE

To evaluate the initial and long-term results of balloon dacryocystoplasty in the treatment of epiphora caused by obstruction of the lacrimal system with analysis of the procedure's favorable effects.

MATERIALS AND METHODS

Four hundred thirty eyes of 350 patients with obstructions of the lacrimal system were enrolled. Dacryocystoplasty was performed with use of a balloon catheter and a ball-tipped guide wire. The lesions were categorized according to cause, severity, site of the obstruction, and diameter and inflation time of the balloon. The technical success, initial success (improvement of symptoms after 1 week), and long-term patency rates were calculated. These rates in each group were compared with the chi(2) test and the Kaplan-Meier method.

RESULTS

The overall technical success rate was 95.3%. The overall initial success rate was 57.4%. There was no significant complication except for mild epistaxis in 12%. The 2-month, 1-year, and 5-year patency rates were 48.2%, 39.4%, and 36.9%, respectively. Initial success was influenced by the severity (P =.014) and the site (P <.001) of the obstruction, and the diameter of the balloon (P =.047). Long-term patency was affected by the site of the obstruction (P <.001) and the balloon inflation time (P <.001). Among the 183 initially ineffective and 88 recurrent cases, 62 underwent repeat balloon dacryocystoplasty, and the initial success rate was 38.7%.

CONCLUSIONS

The initial success rate of balloon dacryocystoplasty is relatively low. However, long-term patency can be expected in cases with initial success. Some additional factors also should be considered for better results.

Automation of nucleic acid extraction for NAT screening of individual blood units

BACKGROUND

Automation of NAT for single units of blood is currently hampered by the labor-intensive steps involved in the extraction of nucleic acids from samples before the amplification procedures. A new method has been developed for the automation of these steps using hydrophilic polyvinylidene fluoride (PVDF) filter plates.

STUDY DESIGN AND METHODS

Quantitative nucleic acid recoveries from sera containing HCV, HIV, HBV, HAV, and human parvovirus B19 and from 3H-labeled HCV RNA were determined in parallel by the semi-automated PVDF method and a single-column method (Qiagen). Quantitative PCR was performed.

RESULTS

Similar recoveries of HCV, HIV, and HBV (with silica beads) were observed with the PVDF method and with the Qiagen single-column method. The sensitivity of the PVDF-based PCR assay for HCV, HIV, and HBV in serially diluted serum samples was always within two serial dilutions of that obtained when the Qiagen single-column method was used in the same assays. With the use of 3H-labeled HCV RNA, recoveries of approximately 70 percent were found by both methods.

CONCLUSION

The PVDF method will permit full automation of the simultaneous extraction of nucleic acid from sera containing HCV, HIV, and HBV. This procedure will permit NAT screening of individual units of blood, will replace the current screening of pools, and will achieve improved blood safety with reduced labor and costs.

Mitochondrial dysfunction by gamma-irradiation accompanies the induction of cytochrome P450 2E1 (CYP2E1) in rat liver

Multiple biological effects are induced by ionizing radiation through dysfunction of cellular organelles, direct interaction with nucleic acids and production of free radical species. The expression of cytochrome P450s was assessed in the livers of 60Co gamma-irradiated rats. Three gray (G) of gamma-irradiation caused CYP2E1 induction with a 3.6-fold increase in the mRNA at 24 h, whereas the expression of CYP1A2 and CYP3A was not changed. Pharmacokinetics of chlorzoxazone, a specific substrate of CYP2E1, was studied in 3 G-irradiated rats. The area under the plasma concentration-time curve from time zero to infinity of 6-hydroxychlorzoxazone and the amount of 6-hydroxychlorzoxazone excreted in 8 h urine were both significantly greater than those in control rats. Hepatic CYP2E1 was not induced in rats exposed to 0.5-1 G of gamma-rays. Rats irradiated at 6-9 G accumulated doses of gamma-rays exhibited smaller increases in the mRNA due to liver injury than those irradiated at a single dose of 3 G gamma-rays. The plasma glucose and insulin levels were not altered in rats with 3 G of gamma-irradiation. As the exposure level of gamma-irradiation increased, the activity of hepatic aconitase, a key enzyme in energy metabolism in mitochondria, was 30-90% decreased. The amount of mitochondrial DNA per gram of wet liver was 50% decreased in rats exposed to 3 G of gamma-rays. These results demonstrated that gamma-ray irradiation at the exposure level inducing organelle dysfunction induced CYP2E1 in the liver, which might be associated with mitochondrial damage, but not with alterations in glucose or insulin levels.

A de novo designed peptide ligase: a mechanistic investigation

A 33-residue de novo designed peptide ligase is reported which catalyzes the template-directed condensation of suitably activated short peptides with catalytic efficiencies in excess of 10(5) ([k(cat)/K(m)]/k(uncat)). The ligase peptide, derived from natural and designed alpha-helical coiled-coil proteins, presents a surface for substrate assembly via formation of a hydrophobic core at the peptide interface. Charged residues flanking the core provide additional binding specificity through electrostatic complementarity. Addition of the template to an equimolar fragment solution results in up to 4100-fold increases in initial reaction rates. Dramatic decreases in efficiency upon mutation of charged residues or increase in ionic strength establishes the importance of electrostatic recognition to ligase efficiency. Although most of the increase in reaction efficiency is due to entropic gain from binding of substrates in close proximity, mechanistic studies with altered substrates demonstrate that the system is highly sensitive to precise ordering at the point of ligation. Taken together these results represent the first example of a peptide catalyst with designed substrate binding sites which can significantly accelerate a bimolecular reaction and support the general viability of alpha-helical protein assemblies in artificial enzyme design.

Infectivity of blood from PCR-positive, HBsAg-negative, anti-HBs-positive cases of resolved hepatitis B infection

BACKGROUND

Numerous reports have noted the existence of sera, particularly from resolving cases of HBV infection, that are positive for HBV DNA by PCR, despite being negative for HBsAg and IgM anti-HBc. If such blood is infective and detectable by HBV NAT screening, it seems desirable to introduce such screening for transfused blood.

STUDY DESIGN AND METHODS

Three chimpanzees were inoculated with serum and lymphocytes from three patients who were HBV DNA PCR positive, but HBsAg negative. The animals were tested over a period of 15 months for HBsAg, anti-HBs, anti-HBc, and HBV DNA by PCR.

RESULTS

All animals remained uninfected.

CONCLUSION

Small amounts of plasma and MNCs from HBV DNA-positive HBsAg-negative blood do not appear to be infectious; however, further studies with larger volumes of inoculum should be conducted.

Effect of a capsular tension ring on the shape of the capsular bag and opening and the intraocular lens

PURPOSE

To evaluate the effect of a capsular tension ring (CTR) on the shape of the capsular bag, the extent of the capsular opening, and the shape of intraocular lenses (IOLs).

SETTING

Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Korea.

METHODS

The corneal button was removed from porcine eyes in vitro. After phacoemulsification was performed, an IOL alone or an IOL and CTR were inserted in the capsular bag in 6 groups of 5 eyes each. The eyes were examined from the posterior aspect using a Miyake technique to assess capsular bag shape and the capsular opening. To evaluate effects of the CTR on IOL shape, rabbit eyes had phacoemulsification and IOL implantation with and without placement of a CTR in vivo. The IOLs were removed from enucleated eyes 3 months postoperatively and compared with unused control IOLs.

RESULTS

The differences between the maximum and minimum diameters of the capsular bags and capsular openings were significantly less in groups with a CTR. Intraocular lens size (difference from haptic to haptic) decreased significantly in eyes with only an IOL compared with normal controls or eyes with both an IOL and CTR.

CONCLUSIONS

The CTR preserved the integrity of the capsular bag diameter, capsular opening, and IOL shape. It is likely that CTR implantation can avert contracture of the capsular bag and capsular opening, preventing IOL decentration.

High-performance liquid chromatographic analysis of a new neuroprotective agent for ischemia-reperfusion damage, KR-31378

A high-performance liquid chromatographic method was developed for the determination of a neuroprotective agent for ischemia-reperfusion damage, KR-31378, in human plasma and urine and in rat tissue homogenates. The method involved deproteinization of the the biological samples with 0.5 volumes of saturated Ba(OH)2, 0.5 volumes of 0.04 M ZnSO4 and 1 volume of acetonitrile. A 80-microl aliqout of the supernatant was injected onto a reversed-phase C18 column. The mobile phase, 50 mM triethylamine acetate : acetonitrile : tetrahydrofuran (65:30:5, v/v/v), was run at a flow rate of 1.0 ml/min. The column effluent was mornitored by a ultraviolet detector set at 310 nm. The retention time of KR-31378 was approximately 6.5 min. The detection limits of KR-31378 in human plasma and urine and rat tissue homogenates were 0.2, 0.5 and 0.5 microg/ml, respectively. The coefficients of variation (within-day and between-day) were below 13.6% for human plasma and urine and rat homogenates. No interferences from endogenous substances were found.

Radiologic anatomy of the rabbit liver on hepatic venography, arteriography, portography, and cholangiography

Seo TS, Oh JH, Lee DH, et al. Radiologic anatomy of the rabbit liver on hepatic venography, arteriography, portography, and cholangiography. Invest Radiol 2001;36:186-192.

RATIONALE AND OBJECTIVES

The radiologic anatomy of rabbit liver has received little study but is important in many experimental investigations.

METHODS

Twenty-four rabbits were studied by using hepatic venograms, aortograms, hepatic arteriograms, cholangiograms, and portograms.

RESULTS

In all cases, the right, middle, and left hepatic veins drained into the inferior vena cava just below the diaphragm, and the caudate lobe hepatic vein drained more inferiorly. The proper hepatic artery was a branch of the common hepatic artery in 96%. The first branch of the proper hepatic artery was the caudate lobe artery. The remaining main hepatic artery was divided into the right and left hepatic arteries. The left hepatic artery was further divided into the medial and lateral segmental branches in 95%. The anatomy of the portal vein or bile duct was the same as the hepatic artery in 100% of cases.

CONCLUSIONS

Knowledge of the normal patterns and variations of the vessels and bile duct will be helpful for experiments of the rabbit liver in future studies.

The effect of lumbar sympathectomy on increased tactile sensitivity in spinal nerve ligated rats

The aim of this study was to investigate the reason for the contradictory results following surgical sympathectomy on increased tactile sensitivity in spinal nerve ligated rats. For this purpose, firstly the results of L5 spinal nerve ligation alone and both L5 and L6 (L5/6) spinal nerve ligation were compared in Sprague-Dawley rats. Secondly, the difference in tactile sensitivity between the plantar surface (the middle glabrous area on the foot pads of the hind paw) and on the toe (the proximal half of the third and fourth toe of the hind paw) after the spinal nerve injury was studied. Third, we divided the L5 spinal nerve ligated rats into two groups, (i.e. low and high threshold groups) based on the degree of tactile sensitivity and investigated the effect of surgical lumbar sympathectomy (L2-L5) on tactile sensitivity in both the plantar and toe areas. The results show that the tactile sensitivities of L5 spinal nerve ligated rats and L5/6 spinal nerve ligated rats were not different. However, tactile sensitivities of the plantar surface were less than those of toe area suggesting that the response from toe is a better indicator of neuropathic pain. Surgical sympathectomy reduced the response from only the toe area and only in the low threshold group. These results suggest that the reason for the contradictory results of surgical sympathectomy in spinal nerve ligation models is, at least in part, the difference in the degree of mechanical allodynia in each study.

Evidence that neurones accumulating amyloid can undergo lysis to form amyloid plaques in Alzheimer's disease

AIMS

Amyloid has recently been shown to accumulate intracellularly in the brains of patients with Alzheimer's disease (AD), yet amyloid plaques are generally thought to arise from gradual extracellular amyloid deposition. We have investigated the possibility of a link between these two apparently conflicting observations.

METHODS AND RESULTS

Immunohistochemistry and digital image analysis was used to examine the detailed localization of beta-amyloid(42) (A beta 42), a major component of amyloid plaques, in the entorhinal cortex and hippocampus of AD brains. A beta 42 first selectively accumulates in the perikaryon of pyramidal cells as discrete, granules that appear to be cathepsin D-positive, suggesting that they may represent lysosomes or lysosome-derived structures. AD brain regions abundantly populated with pyramidal neurones exhibiting excessive A beta 42 accumulations also contained evidence of neuronal lysis. Lysis of these A beta 42-burdened neurones apparently resulted in a local, radial dispersion of their cytoplasmic contents, including A beta 42 and lysosomal enzymes, into the surrounding extracellular space. A nuclear remnant was found at the dense core of many amyloid plaques, strengthening the idea that each amyloid plaque represents the end product of a single neuronal cell lysis. The inverse relationship between the amyloid plaque density and pyramidal cell density in the AD brain regions also supports this possibility, as does the close correlation between plaque size and the size of local pyramidal cells.

CONCLUSIONS

Our findings suggest that excessive intracellular accumulation of A beta 42-positive material in pyramidal cells can result in cell lysis, and that cell lysis is an important source of amyloid plaques and neuronal loss in AD brains.

Studies on the possible mechanisms of protective activity against alpha-amanitin poisoning by aucubin

Aucubin, an iridoid glucoside, was investigated to determine whether it has a stimulating effect on alpha-amanitin excretion in alpha-amanitin intoxicated rats, and whether there is binding activity to calf thymus DNA. High-performance liquid chromatography (HPLC) analysis of alpha-amanitin in rat urine allowed quantitative measurement of the alpha-amanitin concentration with a detection limit of 50 ng/ml. In this system, a group treated with both alpha-amanitin and aucubin showed that alpha-amanitin was excreted about 1.4 times faster than in the alpha-amanitin only treated group. Our previous results showed that the toxicity of alpha-amanitin is due to specific inhibition of RNA polymerase activity and the resultant blockage of the synthesis of certain RNA species in the nucleus. However, no significant activity change on RNA polymerase from Hep G2 cells was observed when aucubin was treated with alpha-amanitin at any concentration tested. Nevertheless, aucubigenin inhibited both DNA polymerase (IC50, 80.5 microg/ml) and RNA polymerase (IC50, 135.0 microg/ml) from the Hep G2 cells. The potential of both alpha-amanitin and aucubin to interact with DNA were examined by spectrophotometric analysis. Alpha-Amanitin showed no significant binding capacity to calf thymus DNA, but aucubin was found to interact with DNA, and the apparent binding constant (Kapp) and apparent number of binding sites per DNA phosphate (Bapp) were 0.45 x 10(4) M(-1) and 1.25, respectively.

Effects of smoking cessation on changes in blood pressure and incidence of hypertension: a 4-year follow-up study

We performed the present study to investigate the effects of smoking cessation on changes in blood pressure and incidence of hypertension. We evaluated 8170 healthy male employees at a steel manufacturing company who had received occupational health examinations at the company's health care center in 1994 and were reexamined in 1998. Adjustment covariates were the baseline age, body mass index, cigarette smoking, alcohol consumption, exercise, family history of hypertension, systolic or diastolic blood pressure, and changes in body mass index and alcohol consumption during the follow-up period. The adjusted relative risks of hypertension in those who had quit smoking for <1, 1 to 3, and >/=3 years were 0.6 (95% CI 0.2 to 1.9), 1.5 (95% CI 0.8 to 2.8), and 3.5 (95% CI 1.7 to 7.4), respectively, compared with current smokers. The trends for increased risk of hypertension for longer periods of smoking cessation were observed in subgroups of those who maintained weight as well as those who gained weight after smoking cessation. The adjusted increments in both systolic and diastolic blood pressure were higher in those who had quit for >/=1 year than in current smokers. These trends among weight losers, as well as gainers and maintainers, were similar. We observed progressive increases in blood pressure with the prolongation of cessation in men, although at this time the mechanism remains unknown and must be clarified. This study implies that the cessation of smoking may result in increases in blood pressure, hypertension, or both.

DNA prime/canarypox boost-based immunotherapy of chronic hepatitis B virus infection in a chimpanzee

There are about 200 million chronic hepatitis B virus (HBV) carriers at high risk of development of cirrhosis and hepatocellular carcinoma. Termination of the carrier state may avert these risks. We have investigated immunotherapy for chronic HBV infection in a chimpanzee HBV carrier using recombinant DNA-based immunization followed by a recombinant canarypox booster. One week after the booster, HBV DNA declined greater than 400-fold and remained undetectable by the quantitative polymerase chain reaction (PCR) assay for 186 weeks. Plasma levels of hepatitis B surface antigen (HBsAg) declined for only a short time. The decline in HBV DNA correlated with a boost in gamma interferon production without a corresponding boost in cytotoxic T lymphocyte levels, and decline in the transcriptional template or covalently closed circular DNA level. Confirmation of these findings requires further studies in chimpanzees and/or in humans.

An azophenol-based chromogenic anion sensor

[figure: see text] A new chromogenic azophenol-thiourea based anion sensor, 2, has been developed. This system allows for the selective colorimetric detection of F-, H2PO4-, and AcO-. Selectivity trends turned out to be dependent upon guest basicity and conformational complementarity between 2 and the guest.

Pharmacological properties of a newly synthesized H(+)/K(+) ATPase inhibitor, 1-(2-methyl-4-methoxyphenyl)-4-

A new compound, 1-(2-methyl-4-methoxyphenyl)-4-[(3-hydroxypropyl)amino]-6-methyl-2,3-dihydropyrrolo[3,2-c]quinoline (DBM-819), given intraduodenally in pylorus-ligated rats, inhibited basal acid secretion with an ED(50) value of 3.5 mg/kg. In addition, DBM-819 reduced histamine- and pentagastrin-stimulated gastric acid secretion with ED(50) values of 4.0 and 5.1 mg/kg, respectively. The duration of the anti-secretory effect was approximately 18 h when DBM-819 was administered orally to rats with a chronic gastric fistula. Oral administration of DBM-819 protected against gastric lesions induced by ethanol, NaOH, indomethacin and aspirin, and the duodenal ulcer induced by cysteamine, in a dose-dependent manner with ED(50) values of 7.0, 20, 3.1, 4.0 and 6.0 mg/kg, respectively. Taken together, these results suggest that DBM-819 acts as an effective oral anti-ulcer agent in vivo, and that DBM-819 could be developed as a new therapeutic agent for peptic ulcer disease.

Biochemical properties of a newly synthesized H(+)/K(+) ATPase inhibitor, 1-(2-methyl-4-methoxyphenyl)-4-

A new compound, 1-(2-methyl-4-methoxyphenyl)-4-[(3-hydroxypropyl)amino]-6-methyl-2,3-dihydropyrrolo[3,2-c]quinoline (DBM-819), inhibited gastric H(+)/K(+) ATPase in the rabbit (EC 3.6.1.3) with an IC(50) value of 5 microM. However, DBM-819 was a weak inhibitor of kidney Na(+)/K(+) ATPase in the dog, indicating that it has selectivity for the gastric H(+)/K(+) ATPase. The inhibition was reversible and non-competitive with respect to the activating cation K(+). The presence of dithiothreitol did not protect the H(+)/K(+) ATPase from inactivation. The inhibition by DBM-819 was potentiated by acid pretreatment of the compound, suggesting that DBM-819 is converted into a more active intermediate under acidic conditions. The results suggest that DBM-819 is a potent, selective and reversible inhibitor of gastric H(+)/K(+) ATPase, and that the essential cysteine residue may not be involved in the DBM-819-mediated inactivation of gastric H(+)/K(+) ATPase.

A bone replaceable artificial bone substitute: cytotoxicity, cell adhesion, proliferation, and alkaline phosphatase activity

Cellular toxicity, cell adhesion and proliferation, and alkaline phosphatase (ALP) activity were investigated for an artificial bone substitute composed of heated carbonate apatite (CAp) and Type I atelocollagen (AtCol) extracted from bovine tail skins (88/12 in %wt/wt). To enhance the intramolecular crosslinking between collagen molecules, the CAp-AtCol substitutes were irradiated by ultraviolet rays (wave length 254 nm) at 4 degrees C for 4 h or vacuum dried at 150 degrees C for 2 h. Cytotoxicity tests by a direct contact method and an extract dilution method revealed that the CAp-AtCol substitutes were cytocompatible for balb 3T3 fibroblasts. Osteoblast adhesion studies demonstrated that the substitute disks composed of 980 degrees C-heated CAp and AtCol were significantly more adhesive for osteoblasts than those of 1,200 degrees C-sintered CAp and AtCol (p < 0.05). Proliferation studies showed that the number of osteoblasts grown in the media containing substitutes of 980 degrees C-heated CAp and AtCol was statistically higher than grown in those of 1,200 degrees C-sintered CAp and AtCol after 5 days (p < 0.05). It was found that osteoblasts grown in the substitutes of 980 degrees C-heated CAp and AtCol only expressed similar ALP activity to the controls. These results suggested that the substitutes consisting of 980 degrees C-heated CAp and AtCol show more favorable interactions with osteoblasts than those of 1,200 degrees C-sintered CAp and AtCol.

Development and performance of an alternative biofilter system

Step tracer tests were carried out on lab-scale biofilters to determine the residence time distributions (RTDs) of gases passing through two types of biofilters: a standard biofilter with vertical gas flow and a modified biofilter with horizontal gas flow. Results were used to define the flow patterns in the reactors. "Non-ideal flow" indicates that the flow reactors did not behave like either type of ideal reactor: the perfectly stirred reactor [often called a "continuously stirred tank reactor" (CSTR)] or the plug-flow reactor. The horizontal biofilter with back-mixing was able to accommodate a shorter residence time without the usual requirement of greater biofilter surface area for increased biofiltration efficiency. Experimental results indicated that the first bed of the modified biofilter behaved like two CSTRs in series, while the second bed may be represented by two or three CSTRs in series. Because of the flow baffles used in the horizontal biofilter system, its performance was more similar to completely mixed systems, and hence, it could not be modeled as a plug-flow reactor. For the standard biofilter, the number of CSTRs was found to be between 2 and 9 depending on the airflow rate. In terms of NH3 removal efficiency and elimination capacity, the standard biofilter was not as good as the modified system; moreover, the second bed of the modified biofilter exhibited greater removal efficiency than the first bed. The elimination rate increased as biofilter load increased. An opposite trend was exhibited with respect to removal efficiency.

Systematic methodology for the design of a flexible keel for energy-storing prosthetic feet

An effective design method is suggested for a flexible keel design for energy-storing prosthetic feet (ESPF). The basic, two-dimensional shape of the keel is based on anthropometric data and normal gait analysis available in the literature. Cost function is defined for the performance evaluation of the keel. Five factors and five levels of their effect on the performance of the keel are established. By use of an orthogonal array table, 25 trials of dynamic simulations of prosthetic walking are designed, from among 3,125 possible combinations, dramatically reducing the number of total simulations needed to examine sufficiently the contribution of each factor to cost function. A prosthetic walking model is built, and a dynamic simulation of prosthetic walking is performed using the finite element method. The contribution of each factor to cost function is investigated by an analysis of variance (ANOVA), and the average main effects of factors for cost function are calculated. The optimum combination of factor levels is obtained by minimisation of cost function. To examine the structural safety of the keel, the deformation and stress distribution of the keel are investigated by static analysis, and failure indices are calculated by three failure criteria. Finally, the optimum flexible keel is designed with increased energy storage capacity, without failure, and suitable for more active prosthetic walking; the recoverable strain energy stored in the optimum ESPF keel is 25.8J.

Monitoring cerebral perfusion after subarachnoid hemorrhage using CT

The aim of this prospective study was to assess the feasibility and diagnostic relevance of repetitive dynamic (contrast-enhanced) CT measurements of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) in the first 3 weeks after aneurysmal subarachnoid hemorrhage (SAH). In 15 patients with SAH, 59 dynamic CT studies including 944 regions of interest (ROI) were analyzed. The results were correlated with the clinical course and time after the event and the occurrence of vasospasm. Values for the entire series were 33.8+/-19.3 ml/100 g/min (CBF), 3.3+/-1.3 ml/100 g (CBV), and 7.3+/-3.9 s (MTT). Significant differences in CBF and CBV were found between ROI in grey and white matter, with time after the event, between patients with significant and absent or minor vasospasm, and between patients with and without a presumed vasospasm-related infarct.

Intranet-based quality improvement documentation at the Veterans Affairs Maryland Health Care System

The Pathology and Laboratory Medicine Service of the Veterans Affairs Maryland Health Care System is inspected biannually by the College of American Pathologists (CAP). As of the year 2000, all documentation in the Anatomic Pathology Section is available to all staff through the VA Intranet. Signed, supporting paper documents are on file in the office of the department chair. For the year 2000 CAP inspection, inspectors conducted their document review by use of these Web-based documents, in which each CAP question had a hyperlink to the corresponding section of the procedure manual. Thus inspectors were able to locate the documents relevant to each question quickly and efficiently. The procedure manuals consist of 87 procedures for surgical pathology, 52 procedures for cytopathology, and 25 procedures for autopsy pathology. Each CAP question requiring documentation had from one to three hyperlinks to the corresponding section of the procedure manual. Intranet documentation allows for easier sharing among decentralized institutions and for centralized updates of the laboratory documentation. These documents can be upgraded to allow for multimedia presentations, including text search for key words, hyperlinks to other documents, and images, audio, and video. Use of Web-based documents can improve the efficiency of the inspection process.

Increased vascular endothelin-1 gene expression with unaltered nitric oxide synthase levels in fructose-induced hypertensive rats

The present study aimed to investigate whether altered expression levels of endothelin-1 (ET-1) and nitric oxide synthase (NOS) are related to the development of insulin-resistant hypertension. Male Sprague-Dawley rats were fed a fructose-rich diet for 5 weeks. Systolic blood pressure significantly increased in fructose-fed rats. While serum free fatty acid (FFA) and plasma nitrite/nitrate (NOx) levels did not significantly differ between the fructose-fed and control groups, plasma insulin and serum triglyceride (TG) concentrations significantly increased in the former. ET-1 mRNA expression in the aorta increased to 195% in fructose-fed rats. Neither the protein expression of constitutive NOS (cNOS) nor that of inducible NOS (iNOS) were significantly affected by fructose feeding. However, NOx levels in the aorta were significantly increased. These results indicate that an increased expression of vascular ET-1 may be causally related to the development of hypertension in fructose-fed rats. However, an altered role of the vascular nitric oxide (NO) pathway may not be primarily involved in the development of fructose-induced hypertension.

Treatment of internal carotid artery dissections with endovascular stent placement: report of two cases

Extracranial carotid artery dissection may manifest as arterial stenosis or occlusion, or as dissecting aneurysm formation. Anticoagulation and/or antiplatelet therapy is the first-line treatment, but because it is effective and less invasive than other procedures, endovascular treatment of carotid artery dissection has recently attracted interest. We encountered two consecutive cases of trauma-related extracranial internal carotid artery dissection, one in the suprabulbar portion and one in the subpetrosal portion. We managed the patient with suprabulbar dissection using a self-expandable metallic stent and managed the patient with subpetrosal dissection using a balloon-expandable metallic stent. In both patients the dissecting aneurysm disappeared, and at follow-up improved luminal patency was observed.