The early stages of filamentous phage phiLf infection require the host transcription factor, Clp

Xanthomonas campestris pv. campestris produces great amounts of an exopolysaccharide (EPS), xanthan gum. Eight eps loci involved in biosynthesis of the EPS were previously located in the chromosome map of strain Xc17. In this study, the eps8 region was cloned, sequenced and found to contain a crp homologue whose deduced amino acid sequence possesses similarity to that of the cyclic AMP receptor protein of bacteria, with the highest identity (97%) being shared with the X. campestris pv. campestris B-1459 clp gene previously shown to be involved in pathogenicity and regulation of the production of xanthan, extracellular enzymes, and pigment (de Crecy-Lagard V., Glaser P., Lejeune P., Sismeiro O., Barber C.E., Daniels M.J., and Danchin A., J. Bacteriol. 172:5877-5883, 1990). Based on sequence identity, pleiotropic effects of the mutation, the ability to complement an Escherichia coli cya crp mutant, and Southern hybridization detecting a single copy in the chromosome, we propose this eps8 gene to be the Xc17 clp. In addition to the previously reported properties, a clp mutant (AU56E) cannot be plaqued with filamentous phage phiLf, although it retains the capability to support phiLf DNA replication and release authentic phage particles upon electroporation of the RF DNA. Infective center assays demonstrated that the frequency of infection is 460- to 7,500-fold lower in AU56E compared to that in the wild-type Xc17. Electron microscopy, which showed no surface appendages other than the monotrichous flagellum, confirmed that AU56E drastically diminishes in the efficiency of phage adsorption. These results suggest Clp to be regulating the biosynthesis of the primary receptor, most likely a type IV pilus. Upstream to clp is a homologue of the E. coli speD gene required for spermidine synthesis. Mutation of the clp flanking regions and transcriptional analyses suggest clp to be monocistronic and the only gene contained at the eps8 locus.

Differential telomerase expression and telomere length in primary intracranial tumors

BACKGROUND

Telomerase activity and telomere length have been shown to be involved in controlling cell proliferation and regulating cell senescence. The authors examined telomerase activity and telomere length in intracranial tumors to determine the clinicopathological behavior of primary intracranial tumors with respect to telomerase expression and alteration of telomere length.

METHODS

Telomerase activity was examined in 139 brain tumor samples. Telomere length was examined in 138 of the 139 samples. These tumors included 61 meningiomas, 27 schwannomas, 19 high-grade neuroepithelial tumors, and 32 low-grade neuroepithelial tumors. Telomerase activity was measured with a telomerase polymerase chain reaction, enzyme-linked immunosolvent assay kit. Telomere length was examined by Southern blot analysis for the terminal restriction fragment length.

RESULTS

Telomerase activity was detected in 39.2% (20/51) of the neuroepithelial tumors. Detection rates were 47.4% (9/19) for anaplastic astrocytomas and glioblastomas and 34.4% (11/32) for low-grade neuroepithelial tumors. However, detectable telomerase activity was found in 30.8% (4/13) of atypical or malignant meningiomas, but was not detected in any schwannomas. There was a highly significant difference in the telomerase detection rate in neuroepithelial or non-neuroepithelial tumors (p = 0.001). Telomere elongation was found in 11.7% (7/60) of all meningiomas, 46.1% (6/13) of atypical or malignant meningiomas, and 14.8% (4/27) of schwannomas. Elongation of telomere length was detected in 12.6% (11/87) of the cases and 23.5% (12/51) in neuroepithelial tumors. This difference was also significant (p < 0.05). Telomere length was reduced in the majority, (75%, 3/4) of malignant or atypical meningiomas with detectable telomerase activity, but only 45% (9/20) of the neuroepithelial tumors.

CONCLUSION

These results indicate that telomerase activation may be a critical step in the pathogenesis of intracranial tumors. Telomere length elongation also indicates a high potential for malignant behavior in these tumors.

Hypertensive caudate hemorrhage prognostic predictor, outcome, and role of external ventricular drainage

BACKGROUND AND PURPOSE

The purpose of the present study was to analyze the outcome and outcome predictors of caudate hemorrhage and role of external ventricular drainage in acute hydrocephalus.

METHODS

Clinical data from 36 consecutive patients with hypertensive caudate hemorrhage was used in the present study. Age, gender, volume of parenchymal hematoma, hematoma in the internal capsule, initial Glasgow Coma Scale (GCS), hydrocephalus, severity of intraventricular hemorrhage, and hemorrhagic dilatation of the fourth ventricle were analyzed for effect on outcome. Effect of external ventricle drainage for hydrocephalus was evaluated by comparing preoperative and postoperative GCS scores.

RESULTS

By univariate analyses, poor outcome was associated with a poor initial GCS score (P=0.016), hydrocephalus (P<0.001), intraventricular hemorrhage severity (P<0.01), and hemorrhagic dilatation of the fourth ventricle (P=0.02). By multivariate analysis, stepwise logistic regression revealed that hydrocephalus was the only independent prognostic factor for poor outcome (P<0.001). Postoperative 48-hour GCS score was better than the preoperative score by use of paired-sample t test (P<0.001).

CONCLUSIONS

Hydrocephalus is the most important predictor of poor outcome. External ventricular drainage response for hydrocephalus was good in the present study, whereas an early decision should be made regarding preoperative neurological condition.

Preload induces troponin I degradation independently of myocardial ischemia

BACKGROUND

Although global ischemia induces troponin I (TnI) degradation, regional ischemia does not. We hypothesized that this disparity is related to preload-induced proteolysis, which varies as a function of the amount of myocardium at risk of ischemia.

METHODS AND RESULTS

Isolated rat hearts were buffer-perfused at controlled levels of preload. Increasing preload to 25 mm Hg in the absence of ischemia produced pronounced TnI degradation (27 kDa versus 31 kDa bands: 16.4 +/- 3.6% versus 4.7 +/- 1.9% in immediately excised controls, P<0.05). TnI degradation could be blocked by preventing the activation of endogenous calpains with 25 micromol/L calpeptin (4.3 +/- 0.6%). This improved function, with left ventricular systolic pressure increasing from 103 +/- 4 mm Hg to 137 +/- 7 mm Hg (P<0.05). Eliminating elevations in preload after global ischemia-induced stunning also prevented TnI degradation.

CONCLUSIONS

Calpain-mediated TnI proteolysis can be dissociated from stunning and arises from elevations in preload rather than ischemia. This raises the possibility that ongoing preload-induced TnI degradation could impair myocardial function long-term.

Early prediction of aphasia outcome in left basal ganglia hemorrhage

OBJECTIVES

The independent predictors of aphasia outcome for patients with left basal ganglia hemorrhage were evaluated.

PATIENTS AND METHODS

We included 140 patients of 1,036 patients with spontaneous intracerebral hemorrhage admitted to our hospital from January 1993 through December 1997. Aphasia was assessed using the aphasia scale of the Scandinavian stroke scale. Univariate and step-wise logistic regression analyses were performed to assess the relationships between the initial aphasia score, age, gender, blood volume, locations of hematoma and aphasia outcome.

RESULTS

Step-wise logistic regression analysis revealed that the following two factors were independently associated with the final aphasia outcome: initial aphasia score (P < 0.0001) and location of hematoma involving the posterior limb of the internal capsule (P = 0.004).

CONCLUSIONS

A particularly high likelihood of poor aphasia outcomes of patients with left basal ganglia hemorrhage are predicted in those who have poor initial aphasia score and whose brain computed tomography shows the hematoma involves the posterior limb of the internal capsule.

Klebsiella brain abscess in adults

BACKGROUND

We analyzed the clinical manifestations and therapeutic outcomes of Klebsiella brain abscesses.

PATIENTS AND METHODS

The clinical data of 15 patients with Klebsiella brain abscesses, retrospectively collected over a 14-year period, were studied.

RESULTS

The 15 patients included 13 cases of Klebsiella pneumoniae infection and two cases of Klebsiella oxytoca. All but one case were community-acquired infections. Locations of all of these abscesses were supratentorial. 12 cases involved a single abscess, and three involved multiple abscesses. Gas formation was also found in two cases (13%). Common predisposing factors included metastatic spread, chronic otitis media and neurosurgical procedures. Among these 15 patients, 11 were treated surgically and four received antibiotics alone. In total, 11 patients survived and four died, with an overall mortality rate of 26.7%.

CONCLUSION

The clinical presentations and therapeutic outcomes varied according to the different Klebsiella species. While debilitating diseases were common in K. pneumoniae infections, they were not common in K. oxytoca infection. And while metastatic septic abscess is a well-known, devastating complication of K. pneumoniae septicemia, usually seen as a brain abscess with a gas-forming appearance, all of these K. oxytoca infections had both otogenic infections and more favorable outcomes.

The effect of elastin damage on the mechanics of the aortic valve

Porcine bioprosthetic heart valves degenerate and fail mechanically through a mechanism that is currently not well understood. It has been suggested that damage to the elastin component of prosthetic valve cusps could be responsible for changes in the mechanical function of the valve that would predispose it to increased damage and ultimate failure. To determine whether damage to elastin can produce the structural and mechanical changes that could initiate the process of bioprosthetic valve degeneration, we developed an elastase treatment protocol that fragments elastin and negates its mechanical contribution to the valve tissue. Valve cusps were mechanically tested before and after digestion to measure the mechanical changes resulting from elastin damage. Elastin damage produced a decrease in radial and circumferential extensibility (from 43 to 18% strain radially and 12 to 7% strain circumferentially), with a slight increase in stiffness (1.3-2.6kN/m for radial and 10.6-11.9kN/m for circumferential directions). Digestions with trypsin, which does not cleave elastin, confirmed that the changes in mechanics of the circumferential samples were likely due to the nonspecific removal of proteoglycans by elastase, while the changes in the radial samples were indeed due to elastin damage. Removing the mechanical contribution of elastin alters the mechanical behavior of the aortic valve cusp, primarily in the radial direction. This finding implies that damage to elastin will distend the cusps, reduce their extensibility, and increase their stiffness. Damage to elastin may therefore contribute to the degeneration and failure of prosthetic valves.

Effect of isoflurane versus nicardipine on blood flow of lumbar paraspinal muscles during controlled hypotension for spinal surgery

STUDY DESIGN

This study compared the effects of isoflurane and nicardipine on regional blood flow of the lumbar paraspinal muscles.

OBJECTIVES

The purpose of this study was to determine whether treatment with hypotensive agents result in ischemia of the lumbar paraspinal muscles, thereby facilitating surgical procedures.

SUMMARY OF BACKGROUND DATA

Despite the general acceptance of controlled hypotension as effective in reducing blood loss during spinal surgery, the changes of blood flow that occur at the lumbar paraspinal muscles when this technique is applied remain unclear. The use of laser Doppler flowmetry allows changes of muscle blood flow to be easily detected in real time with minimal invasion, thereby allowing differences among distinct pharmacological approaches for induction and maintenance of controlled hypotension to be evaluated.

METHODS

The prehypotensive and hypotensive (reduction of mean arterial pressure by 20 mm Hg) blood flow of the lumbar paraspinal muscles were assessed with a laser Doppler flowmeter in 40 patients undergoing lumbar spinal surgery. The first half of the patients (n = 20) received isoflurane, whereas the second half received nicardipine to achieve arterial hypotension.

RESULTS

Compared with the prehypotensive state, during the hypotensive state, patients in the isoflurane group exhibited a 17% to 46% (mean, 33.7%) decrease in lumbar paraspinal muscle blood flow, whereas patients in the nicardipine group exhibited a 24% to 177% (mean, 82.5%) increase in lumbar paraspinal muscle blood flow. Statistical analysis showed a significant difference in the changes of flux after induced hypotension between the isoflurane and nicardipine group (P < 0.001).

CONCLUSIONS

Depending on the pharmacological treatment used to achieve arterial hypotension in spine surgery, there will be either a reduction in paraspinal muscle blood flow (ischemia) or an enhancement of this blood flow (hyperemia).

Patterns of palmar skin temperature alterations during transthoracic endoscopic T2 sympathectomy for palmar hyperhidrosis

Transthoracic endoscopic T2 sympathectomy has been widely applied to the treatment of a variety of sympathetically mediated disorders. Palmar hyperhidrosis is probably the most common indication for thoracic sympathectomy, especially in certain subtropical areas. Which sympathetic ganglion is to be ablated and how extensive such ablation is enough to eliminate palm sweating are two important issues. Intraoperative monitoring of palmar skin temperature (PST) is the most frequently used method for assessing the accuracy as well as adequacy of ablation of the target sympathetic ganglia. With continuous monitoring of bilateral PST during the operative course of T2 sympathectomy, it was possible to depict the alterations of bilateral PST in response to specific surgical procedures in a real-time manner. For each case, a PST graph was obtained, which represented the graphical expression of intraoperatively recorded bilateral PST data plotted against time. The PST graphs of 93 consecutive cases were analysed. Three types of PST graphs existed, reflecting different responses of bilateral PST to different surgical procedures during the operation. In Type I PST graph pattern, found in 58 cases, skin incision and intercostal muscle dissection caused dramatic bilateral PST drop; and unilateral T2 sympathectomy induced synchronous bilateral PST elevation. Twenty-four cases demonstrated Type II PST graph pattern, in which unilateral T2 sympathectomy caused only ipsilateral PST elevation, although the PST-depressing effect of skin incision and muscle dissection was as significant as in Type I graph pattern. In the 11 cases who showed Type III PST graph pattern, neither skin incision nor T2 sympathectomy induced any apparent changes of PST on either side, giving rise to two rather flat PST curves on the PST graphs. These findings implicate that reciprocal interactions between bilateral sympathetic activities exist in the majority of cases, and that crossover sympathetic modulation may play a role in the neural control of the sudomotor and vasomotor activities of the palms. This study also provides information regarding how PST would possibly change following specific surgical procedures during transthoracic endoscopic T2 sympathectomy, which may be of importance to those who use intraoperative PST monitoring as a guide in determining whether or not the correct sympathetic ganglia are ablated for adequate sympathetic denervation of the palms.

Failure of prevention against postoperative vomiting by ondansetron or prochlorperazine in patients undergoing gynecological laparoscopy

BACKGROUND

Ondansetron has been approved for the treatment and prevention of postoperative emesis. Since it is presumably considered to possess potent antiemetic effect with fewer side effects, the administration of ondansetron to inhibit emesis in patients following gynecological laparoscopic surgery might be recommendable. Hence, we examined the effects of intravenous ondansetron at dosage of 4 and 8 mg in comparison with intravenous prochlorperazine at 5 mg and placebo.

METHODS

A total of 120 patients were allocated randomly into 3 groups. Group 1 patients who served as control were given NaCl 0.9% 4 mL (placebo) intravenously (i.v.); patients in group 2 and group 3 were given ondansetron 4 mg ondansetron 8 mg i.v. respectively; patients in group 4 were given prochlorperazine 5 mg i.v. Premedication was omitted.

RESULTS

Logistic regression analysis adjusted for prognostic factors revealed no significant difference between 5 mg prochlorperazine group and 4 mg or 8 mg ondansetron group as compared over the 24 h study period.

CONCLUSIONS

The results of this study suggest that i.v. 4 or 8 mg ondansetron and 5 mg prochlorperazine were not effective in prevention of postoperative emesis in patients undergoing gynecological laparoscopy. Since the cost of ondansetron is high, its routine use for prevention against postoperative nausea and vomiting is not be recommended clinically because of its uncertain benefit.

Interobserver agreement in the electrocardiographic diagnosis of acute myocardial infarction in patients with left bundle branch block

STUDY OBJECTIVE

To determine the interobserver agreement between cardiologists and emergency physicians in the ECG diagnosis of acute myocardial infarction (AMI) in patients with left bundle branch block (LBBB) using the ECG algorithm previously described by Sgarbossa et al.

METHODS

Using the Sgarbossa ECG algorithm, 4 cardiologists and 4 emergency physicians independently interpreted a test set of 224 ECGs with LBBB, of which 100 ECGs were from patients with an evolving AMI. A subset of 25 ECGs was reinterpreted by each reader to test intraobserver agreement for AMI as well as interobserver agreement for the degree of ST-segment deviation. Agreement rates for AMI were estimated using the kappa statistic. In addition, the sensitivity and specificity for diagnosing AMI were determined for each reader, using the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO I) enzyme criteria for AMI as the gold standard. The study was conducted at 3 university-affiliated medical centers. The test set contained ECGs from 100 patients enrolled in the GUSTO I trial with LBBB on their initial ECG and an evolving AMI confirmed by serum cardiac enzyme changes, and 124 control patients from the Duke Databank for Cardiovascular Disease who had stable, angiographically documented coronary artery disease and LBBB.

RESULTS

There was excellent interobserver agreement (kappa=0.81, 95% confidence interval [CI] 0.80 to 0.83) between cardiologists and emergency physicians for diagnosing AMI. Intraobserver agreement kappa values for AMI diagnosis by cardiologists and emergency physicians were 0.81 (95% CI 0.67 to 0.94) and 0.71 (95% CI 0.54 to 0.89). The median sensitivity for diagnosing AMI by cardiologists and emergency physicians was 73% (range 66% to 80%) versus 67% (range 61% to 75%); median specificity was 98% (range 97% to 99%) versus 99% (range 98% to 99%). Spearman rank correlation coefficients for the degree of ST-segment deviation in all 12 leads was 0.86 (95% CI 0.85 to 0.87) among all readers.

CONCLUSION

There is excellent interobserver agreement between cardiologists and emergency physicians for diagnosing AMI when applying the Sgarbossa ECG algorithm to patients with LBBB. Emergency physicians should be able to reliably use this algorithm when evaluating patients.

Arsenite induces p53 accumulation through an ATM-dependent pathway in human fibroblasts

Arsenic compounds are potent human carcinogens. Accumulated evidence has shown that arsenite-induced cytogenetic alterations are associated with the carcinogenicity of arsenic. Because p53 plays a guarding role in maintaining genome integrity and accuracy of chromosome segregation, the mechanistic effects of arsenite on p53 activation were analyzed. In the present study, arsenite-induced DNA strand breaks were confirmed by alkaline single-cell gel electrophoresis (comet assay) in human fibroblast (HFW) cells. Accompanying the appearance of DNA strand breaks was a significant accumulation of p53 in arsenite-treated HFW cells, as demonstrated by immunoblotting and immunofluorescence techniques. p53 downstream proteins, such as p21 and the human homologue of murine double minute-2, were also significantly induced by arsenite treatment. Cell cycle retardation and G2-M arrest were observed in 5-bromo-2'-deoxyuridine pulse-labeled HFW cells by flow cytometry. Wortmannin, an inhibitor of phosphatidylinositol 3-kinases, inhibited arsenite- or X-ray irradiation-induced p53 accumulation but did not alter UV irradiation- or N-acetyl-Leu-Leu-norleucinal-induced p53 accumulation. p53 phosphorylation on serine 15 was also confirmed by immunoblotting technique in arsenite- and X-ray-treated HFW cells but was not observed in UV- or N-acetyl-Leu-Leu-norleucinal-treated HFW cells. These results suggest the involvement of a phosphatidylinositol 3-kinase-related protein kinase in arsenite-induced p53 accumulation. For confirmation, we demonstrated that arsenite treatment, similar to X-ray irradiation, did not induce p53 accumulation in GM3395 fibroblasts derived from a patient with ataxia telangiectasia. In contrast, UV irradiation did cause p53 accumulation in these cells. Together, these findings infer that arsenite-induced DNA strand breaks may lead to p53 phosphorylation and accumulation through an ataxia telangiectasia mutated-dependent pathway in HFW cells.

Calpain-mediated proteolytic cleavage of troponin I induced by hypoxia or metabolic inhibition in cultured neonatal cardiomyocytes

While ischemic damage to myofibrillar proteins is thought to be responsible in part for depressed cardiac function, the relation between myofilament protein breakdown and chronic hypoxia has not been defined. We previously characterized a chemical hypoxia model of neonatal cardiomyocytes mediated by 1 mM azide that exhibits features of calpain activation (Mol Cell Biochem 178:141-149, 1998). We here show that both hypoxia and azide-mediated metabolic inhibition induced heme oxygenase-1 expression, and caused cell death associated with lipid peroxidation. While blocking calcium influx or inhibiting calpain activity efficiently attenuated hypoxia-induced cell injury, it failed to prevent cell injury caused by adenoviral overexpression of the tumor suppressor protein p53. Inhibitors of caspases, on the other hand, suppressed cell injury caused by p53 overexpression. Hypoxia caused selective cleavage of troponin I (TnI), which could be suppressed by either nifedipine or calpeptin. Other myofilament proteins such as troponin T, myosin heavy chain, and actin appeared to remain largely intact. p53-mediated cell injury exhibited proteolysis of the caspase protein substrate lamin B without appreciable breakdown of TnI. We suggest that calpain-induced TnI breakdown may constitute a unique biochemical marker associated with chronically hypoxic cardiomyocytes.

Blockade of endothelin receptors markedly reduces atherosclerosis in LDL receptor deficient mice: role of endothelin in macrophage foam cell formation

OBJECTIVE

We evaluated the direct effects of long-term blockade of ET(A) and ET(B) receptors using a mixed endothelin (ET) receptor antagonist, LU224332, in the low density lipoprotein receptor (LDL-R) knockout mouse model of atherosclerosis.

METHODS

Four groups of LDL-R deficient mice were studied: control mice fed normal chow (group I); mice fed a high cholesterol (HC, 1.25%) diet alone (group II), HC fed animals treated with LU224332 (group III); and mice fed normal chow treated with the LU compound (group IV). All treatments were continued for 8 weeks at which time the animals were sacrificed and the aortae were removed and stained with oil red O. Atherosclerotic area (AA) was determined by quantitative morphometry and normalized relative to total aortic area (TA).

RESULTS

Cholesterol feeding resulted in a marked increased in total plasma cholesterol ( approximately 15 fold) and widespread aortic atherosclerosis (AA/TA: group I: 0.013+/-0.007; group II: 0.33+/-0. 11; P<0.001). Atherosclerotic lesions were characterized by immunohistochemistry as consisting mainly of macrophages which also showed high levels of ET-1 expression. Treatment with ET antagonist significantly reduced the development of atherosclerosis (AA/TA: group III: 0.19+/-0.07, P<0.01 vs. group II), without altering plasma cholesterol levels and blood pressure. The direct effect of LU224332 on macrophage activation and foam-cell formation was determined in vitro using a human macrophage cell line, THP-1. Treatment of the THP-1 cells with LU224332 significantly reduced cholesterol ester and triacylglycerol accumulation and foam-cell formation on exposure to oxidized LDL (P<0.01 and P<0.05, respectively).

CONCLUSION

We conclude that a nonselective ET receptor antagonist substantially inhibited the development of atherosclerosis in a genetic model of hyperlipidemia, possibly by inhibiting macrophage foam-cell formation, suggesting a role for these agents in the treatment and prevention of atherosclerotic vascular disease.

Disgust sensitivity and contamination fears in spider and blood-injection-injury phobias

Disgust has been implicated in the onset and maintenance of blood-injection-injury (BII) and animal phobias. Research suggests that people with these phobias are characterized by an elevated sensitivity to disgust-evoking stimuli separate from their phobic concerns. The disgust response has been described as the rejection of potential contaminants. Disgust-motivated avoidance of phobic stimuli may therefore be related to fears of contamination or infection. The present study compared BII phobics, spider phobics and nonphobics on two measures of disgust sensitivity and two measures of contamination fears. Positive correlations were found between disgust sensitivity and contamination fear. Specific phobics scored higher than nonphobics on all scales and BII phobics scored higher than spider phobics on contamination fear measures. Furthermore, the contamination fear scales were correlated with the blood phobia measure, but not correlated with the spider phobia measure. The results suggest that while both phobias are characterized by elevated disgust sensitivity, contamination fear is more prominent in BII than spider phobia.

Tin-protoporphyrin potentiates arsenite-induced DNA strand breaks, chromatid breaks and kinetochore-negative micronuclei in human fibroblasts

Numerous reports have shown that oxidative stress is involved in arsenite-induced genetic damage. Arsenite is also a potent inducer of heme oxygenase (HO)-1. To understand whether HO-1 could function as a cellular antioxidant and protect cells from arsenite injury, the effects of tin-protoporphyrin (SnPP), a competitive inhibitor of HO-1, on arsenite-induced genetic damage were examined in human skin fibroblasts (HFW). In the present study, we found that SnPP at 100 microM significantly potentiated arsenite-induced cytotoxicity, DNA strand breaks (assayed by alkaline single cell gel electrophoresis(SCGE)), and chromatid breaks. Although arsenite alone mainly induced kinetochore-plus micronuclei (K(+)-MN), SnPP only synergistically enhanced kinetochore-negative micronuclei (K(-)-MN). The increase in K(-)-MN by SnPP cotreatment was consistent with the increase in DNA strand breaks and chromatid breaks caused by SnPP. However, at higher arsenite doses, K(+)-MN was significantly reduced by SnPP. Pretreatment of HFW cells with hemin, an inducer of HO-1, significantly attenuated the cytotoxicity of arsenite. Therefore, the present results suggest that HO-1 induction by arsenite plays certain roles in protecting cells from arsenite-induced injury.

K-wire position in tension band wiring of the olecranon - a comparison of two techniques

Tension band wiring is a recognised standard treatment for olecranon fractures. We studied the effect of K-wire position on backing out of the wire in a group of 80 patients with closed transverse olecranon fractures with a minimum follow-up time of 9 months. The rate of wires backing out as seen on X-ray was three times greater in patients who had K-wires passed down the long axis of the ulna rather than across the anterior cortex as recommended by the AO group. There was a corresponding higher rate of local complications in these patients. 42% of this group had to have the metal removed compared with 11.4% of the transcortical group. We compared the biomechanical properties of both K-wires positions in a human cadaveric model. The maximum pull-out strength for each configuration was recorded in 20 elbow joints. The average maximum pullout strength for the intramedullary wires was 56.3 N (range 27. 7-95.6 N) and 122.7 N for the transcortical wires (range 56.7-201.2). The results of both the clinical study and biomechanical data support the routine use of transcortical placement of K-wires in tension-band wiring of transverse olecranon fractures.

Determination of 14 elements in Taiwanese bones

The objective of this study was to measure the concentration of 14 elements in human bone and investigate the affecting factors. This study aims to establish a database of elements in Taiwanese bone. Seventy-seven bone samples were taken from 70 subjects who were undertaking various bone surgeries from a medical center in central Taiwan. Bone samples were pretreated using microwave digestion and then, after determining the optimal conditions for analysis, fourteen elements were analyzed using Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). Results showed that Ca had the highest concentration, followed by Mg and Zn. The lowest concentrations were of Mn, followed by Cd and Co. There was a positive correlation between the frequency of seafood intake and presence of all the 14 elements in human bone. There were several elements that had positive inter-correlation: As with Co; Al, Ag and Ca; Ni with Co, Mn and Al; Co with Al, Ag and Ca; Mn with Cr and Cu; Cr with Cu; Mg with Ca; Al with Ag and Ca; Ag with Ca; and also Zn with Mg. There were no significant differences found between concentrations of elements and etiology of bone disease and age. The authors suggest that further studies be conducted to establish a normal value of elements in human bone in Taiwan. This will greatly benefit the understanding of the relationship between disease pattern and elements in human bone.

Delayed apnea in patients with mid- to lower cervical spinal cord injury

STUDY DESIGN

A retrospective study of 36 patients with mid- to lower cervical spinal cord injury (CSCI) divided into two groups based on whether delayed apnea developed.

OBJECTIVES

To determine nonpulmonary risk factors associated with the development of delayed apnea in mid- to lower cervical spinal cord injury.

SUMMARY OF BACKGROUND DATA

Patients with mid- to lower cervical spinal cord injury are generally at lower risk of developing respiratory failure than those with high cervical spinal cord injury. Respiratory failure manifesting as sudden apnea may occur days or even weeks after injury without any pulmonary complications in such patients.

METHODS

An index group of eight patients with complete mid- to lower cervical spinal cord injury in whom delayed catastrophic apnea occurred were reviewed. Another group of 28 patients with cervical spinal cord injury of identical magnitude and presentation but without respiratory failure served as the control group. Six parameters presumed to be related to the delayed apnea were analyzed.

RESULTS

The extent of cord lesions was significantly different, being diffuse in most of the index patients, but focal in the majority of the control patients (P<0.001). Involvement of the C4 segment of cord appeared to be more frequent in the index group; however, the difference was not statistically significant (P = 0.091). The incidence of transient bradycardia (P<0.01) and dyspnea (P<0.001) in the index group was significantly higher than in the control group. Paralytic ileus was a much rarer event and found to be unrelated to the occurrence of apnea. In five of the eight index patients, the apnea occurred during sleep. Six of the eight index patients died of it.

CONCLUSIONS

Delayed but devastating apnea may develop in patients with mid- to lower cervical cervical spinal cord injury, even when they are clinically stable and free from any pulmonary complications. The presence of diffuse, extensive cord lesions, respiratory distress, or bradycardia with or without associated hypotension, however transient and self-limited, should be regarded as warning signs. Sleep was found to be a risky period of time.

Abnormal aortic valve development in mice lacking endothelial nitric oxide synthase

BACKGROUND

Endothelium-derived nitric oxide (NO) is produced by an oxidative reaction catalyzed by endothelial NO synthase (eNOS). NO plays a crucial role in controlling cell growth and apoptosis, as well as having well-characterized vasodilator and antithrombotic actions. More recently, endothelium-derived NO was shown to be involved in postdevelopmental vascular remodeling and angiogenesis, as well as in the formation of limb vasculature during embryogenesis. Therefore, we investigated the role of endothelium-derived NO during cardiovascular development using mice deficient in eNOS.

METHODS AND RESULTS

We examined the hearts of 12 mature eNOS-deficient and 26 mature wild-type mice. Five of the mature eNOS-deficient mice had a bicuspid aortic valve; none of the 26 wild-type animals exhibited identifiable valvular or cardiac abnormalities. Immunohistochemical analysis revealed prominent eNOS expression localized to the endothelium lining the valve cusps of the aorta in mature wild-type mice; expression was localized to the myocardium and endothelial cell monolayer lining the valve leaflets in the developing embryo.

CONCLUSIONS

These results show a strong association between eNOS deficiency and the presence of a bicuspid aortic valve; they provide the first molecular insight into one of the most common types of congenital cardiac abnormality.

Biaxial strain properties of elastase-digested porcine aortic valves

BACKGROUND AND AIMS OF THE STUDY

Previous studies have suggested that elastin in porcine aortic valve cusps is responsible for restoring collagen fibers to their original configuration between loading-unloading cycles.

METHODS

Biaxial loading tests were performed on intact aortic valves before and after elastase treatment to further investigate the role of elastin.

RESULTS

Degradation of elastin caused an increase in the radial dimensions of the cusps (mean increase in gauge length, 29%), which corresponded to a significant decrease in radial extensibility (mean decrease, 61%) and a threefold increase in radial stiffness. Changes in circumferential extensibility and stiffness were smaller and, for most cusps, were not statistically significant. Control experiments, in which the valves were treated with buffer only, resulted in the opposite changes in radial dimensions and extensibility (7% decrease in gauge length and doubling of extensibility).

CONCLUSION

Changes in the mechanical properties of the aortic valve cusps following incubation in elastase were due to elastin damage, and not incidental to soaking in buffer. As many explanted bioprosthetic valves have mechanical characteristics similar to those of the elastase-treated valves, elastin damage may be a factor in the progressive degeneration and ultimate failure of bioprosthetic heart valves.

Correlation of lycopene measured by HPLC with the L, a, b color readings of a hydroponic tomato and the relationship of maturity with color and lycopene content

Tomatoes (Lycopersicon esculentum cv. Laura) were separated, according to the ripening stage, by a sensory panel into seven groups, and color was measured on the tomato surface with a Minolta Chroma meter. The L, a, b, hue, chroma, and lycopene content were plotted against the maturity stages of the tomatoes, and several good correlations were found. The a/b ratio and the lycopene content were the parameters that allowed six of seven maturity groups in the tomato to be statistically distinguished. The lycopene content, measured by HPLC, was also correlated with the color measurements, and the a, a/b, and (a/b)(2) color factors produced the best regressions. An estimation of the lycopene content in tomatoes can be achieved by using a portable chroma meter, with a possible field usage application. Equations to calculate the lycopene content of tomatoes based on the color readings are reported.

Quality comparison of hydroponic tomatoes (Lycopersicon esculentum) ripened on and off vine

There is a general belief that the quality of tomatoes ripened on vine is better than tomatoes ripened off the vine, influencing among other parameters, the price of this commodity. We compared the quality of hydroponic tomatoes ripened on and off vine by chemical, physical, and sensory evaluation to find what attributes are affected and to what extent. Lycopene, beta-carotene, total and soluble solids, moisture content, ascorbic acid, acidity, pH, texture, and color were analyzed. Tomatoes ripened on vine had significantly more lycopene, beta-carotene, soluble and total solids, higher a* and lower L*, and were firmer. However, a 100-judge panel rated only the color and overall liking of the vine-ripened tomatoes as more intense than the fruit ripened off vine. Therefore, the chemical and physical differences were mostly not large enough to influence the panelist's perception. The characterization of tomatoes ripened on and off vine may help to guide post-harvest handling and treatment and to improve the quality of tomatoes ripened off vine.

Arsanilic acid-Sepharose chromatography of pyruvate kinase from KB cells

In the present study, arsanical-based affinity chromatography for pyruvate kinase (PK) isolation was explored. p-Arsanilic acid (4-aminophenyl arsonic acid), which contains an arsonic acid moiety structurally similar to inorganic pentavalent arsenate, was conjugated to Sepharose 4B via its para-amino group to form an As(V)-Sepharose matrix. The cellular proteins from KB cells bound to arsonic acid moieties were eluted by 50 mM sodium arsenate in Tris-HCl buffer (50 mM, pH 7.6). A single protein band with a molecular mass of 58 kDa was shown on a sodium dodecyl sulfate-polyacrylamide gel. By immunoblotting, amino acid sequencing and enzymatic analysis, the sodium arsenate-eluted 58-kDa protein was demonstrated to be a human PK (type M2). By using this one-step As(V)-Sepharose chromatography, PK from KB cells was purified 35.4-fold with a specific activity of 153.15 U/mg protein in the presence of 6 mM fructose-1,6-biphosphate. Although PK was eluted from an As(V)-Sepharose column with sodium arsenate, PK activity was apparently inhibited by the used eluent system, but not by p-arsanilic acid, indicating a specific interaction of As(V) to PK. In summary, our results indicate that As(V)-Sepharose can serve as a simple and efficient chromatographic support for PK purification from KB cells.