Identification of the indoleamine 2,3-dioxygenase nucleotide sequence in a rat liver transplant model

A tryptophan catabolizer, indoleamine 2,3-dioxygenase (IDO) is highly expressed in the placenta and plays an essential role in maternal tolerance. Recent data have shown that the administration of an IDO inhibitor blocked not only maternal tolerance but also liver allograft tolerance. However, little is known about the induction of IDO in liver allografts, although a gene specific for tryptophan 2,3-dioxygenase (TDO) is believed to be expressed in the liver. In the present study, we investigated whether IDO is induced in liver allografts. Synthetic oligonucleotide primers based on the mouse IDO cDNA sequence were used to amplify RNA derived from livers of donor, syngeneic or allogeneic OLT rats. RNA encoding IDO was induced in the rat allogeneic liver after orthotopic liver transplantation (OLT), but not in syngeneic OLT. The rat nucleotide sequence of the RT-PCR products obtained from OLT livers revealed identities of 89% homology to the mouse IDO and of 68% to the human IDO. This study demonstrated the presence of RNA encoding IDO in allogeneic OLT livers, which may be involved in the immune response after liver transplantation.

Effects of VEGF121 and/or VEGF165 gene transfection on collateral circulation development

BACKGROUND AND PURPOSE

Angiogenesis is regulated by various factors, including vascular endothelial growth factor (VEGF). Five isoforms of VEGF have been discovered: VEGF121, VEGF145, VEGF165, VEGF189, and VEGF206. The teleologic basis for the various VEGF isoforms remains unclear, but different VEGF isoforms may mediate distinct endothelial cell functions such as angiogenesis, vascular permeability, and differentiation. We sought to determine the effects of various VEGF isoforms on angiogenesis under ischemic conditions in rabbits.

METHODS

The effects of VEGF121 and/or VEGF165 gene transfection on collateral circulation development in ischemic rabbit hindlimb muscles were investigated by using naked plasmids encoding VEGF121 or VEGF165 (pVEGF121 or pVEGF165), either individually or in combination. pCMV beta was used as the control plasmid. The femoral artery on one side of New Zealand White rabbits was ligated. Ten days later, the ischemic muscles received direct intramuscular injection of pVEGF121 (500 micrograms), pVEGF165 (500 micrograms), or pVEGF121 (250 micrograms) + pVEGF165 (250 micrograms) in experimental groups, while pCMV beta (500 micrograms) was used in the control group. Therapeutic effects were evaluated 30 days later by anatomic and physiologic analysis.

RESULTS

Internal iliac angiography showed strong development of collateral circulation in all of the pVEGF-treated groups. In contrast, collateral arteries developed weakly in the control group. Combination treatment with both pVEGF121 and pVEGF165 did not result in additional improvement compared with pVEGF121 or pVEGF165 treatment alone (angiographic scores: pVEGF121 = 0.85 +/- 0.10; pVEGF165 = 0.81 +/- 0.11; pVEGF121 + pVEGF165 = 0.83 +/- 0.09; control = 0.53 +/- 0.09; p < 0.01). A favorable response in the development of circulation at the capillary level with pVEGF121 and/or pVEGF165 versus pCMV beta was also found. Blood pressure measurement and regional blood flow measurement using colored microspheres revealed similar results.

CONCLUSIONS

Our results show that direct intramuscular injection of naked DNA encoding VEGF121 or VEGF165, individually or in combination, is an effective method for gene transfer in an animal model of ischemic limbs and results in augmented collateral vascular development and tissue perfusion.

Lattice boltzmann method on composite grids

A composite block-structured lattice Boltzmann method is proposed for the simulation of two-dimensional incompressible fluid flows. The grid structure is composed of a coarse base grid and one or several fine grid(s). The former covers the entire physical domain; the latter are placed at regions where local grid refinement is desirable. The simulation is first carried out on the base grid level at a smaller relaxation time, allowing a rapid propagation of boundary information throughout the entire domain. Thus large-scale flow features can be resolved efficiently at a relatively low cost. At a later time, fine grid variables are initiated. The dependent variables on both grid levels are, then, advanced in time simultaneously with the fine grid boundary conditions obtained from the base grid solution at the grid interface. As a demonstration, the lid-driven cavity flow is selected for study. The results show good agreement with benchmark numerical data and those calculated from the finite-volume U2RANS model. The proposed method is able to produce accurate solutions on fine grids, with a considerable saving in CPU time.

Delayed administration of the K+ channel activator cromakalim attenuates cerebral vasospasm after experimental subarachnoid hemorrhage

BACKGROUND

Delayed cerebral vasospasm remains an unpredictable and inadequately treated complication of aneurysmal subarachnoid hemorrhage (SAH). Recent evidence indicates that the potassium channel activator cromakalim is capable of limiting cerebral vasospasm in rabbits when administered immediately after experimental SAH (i.e. before spastic constriction has been initiated). However, the ultimate clinical value of cromakalim for treating vasospasm will depend in part on its effectiveness when administered after SAH-induced constriction has already been initiated. The present study examined the effects of cromakalim on vasospasm when treatment was initiated after SAH-induced constriction was underway.

METHODS

New Zealand white rabbits were subjected to experimental SAH by injecting autologous blood into the cisterna magna. Cromakalim (0.03, 0.1 or 0.3 mg/kg) or vehicle was injected intravenously at 8 hour intervals beginning 24 hours post-SAH. Animals were killed by perfusion fixation 48 hours after SAH. Basilar arteries were removed and sectioned, and cross-sectional area was measured.

FINDINGS

The average cross sectional areas of basilar arteries were reduced by 64% and 68% in the SAH-only and SAH + vehicle groups, respectively. Treatment with cromakalim dose-dependently attenuated SAH-induced constriction. The groups treated with 0.03, 0. 1, and 0.3 mg/kg cromakalim exhibited average decreases in cross-sectional area of 57%, 42%, and 19%, respectively.

INTERPRETATION

These findings indicate that cromakalim dose-dependently attenuates cerebral vasospasm when administered 24 hours after experimental SAH in the rabbit. The results suggest K(ATP) channel activators, such as cromakalim. could be of benefit for reversing cerebral vasospasm after aneurysmal SAH.

Binding of retinol induces changes in rat cellular retinol-binding protein II conformation and backbone dynamics

The structure and backbone dynamics of rat holo cellular retinol-binding protein II (holo-CRBP II) in solution has been determined by multidimensional NMR. The final structure ensemble was based on 3980 distance and 30 dihedral angle restraints, and was calculated using metric matrix distance geometry with pairwise Gaussian metrization followed by simulated annealing. The average RMS deviation of the backbone atoms for the final 25 structures relative to their mean coordinates is 0.85(+/-0.09) A. Comparison of the solution structure of holo-CRBP II with apo-CRBP II indicates that the protein undergoes conformational changes not previously observed in crystalline CRBP II, affecting residues 28-35 of the helix-turn-helix, residues 37-38 of the subsequent linker, as well as the beta-hairpin C-D, E-F and G-H loops. The bound retinol is completely buried inside the binding cavity and oriented as in the crystal structure. The order parameters derived from the (15)N T(1), T(2) and steady-state NOE parameters show that the backbone dynamics of holo-CRBP II is restricted throughout the polypeptide. The T(2) derived apparent backbone exchange rate and amide (1)H exchange rate both indicate that the microsecond to second timescale conformational exchange occurring in the portal region of the apo form has been suppressed in the holo form.

Species of Caligus Müller, 1785 (Copepoda: Caligidae) parasitic on marine fishes of Taiwan

Six species of copepods of the genus Caligus (Caligidae, Siphonostomatoida) parasitic on marine fishes of Taiwan are reported. They are: C. absens n. sp. from Priacanthus blochii and P. macracanthus; C. epinepheli Yamaguti, 1936 from Scolopsis vosmeri; C. kanagurta Pillai, 1961 from Decrapterts kurroides; C. laticaudus Shiino, 1960 from Lutjanus vitta and Parapristiopoma trilineatum; C. nengai Rangnekar, Rangnekar & Murti, 1953 from Triacanthus biaculeatus; and C. rotundigenitalis Yü, 1933 from Drepane punctata, Liza macrolepis and Terapon jarbua. C. distortus Pillai & Natarajan, 1977 is relegated to a synonym of C. nengai and C. multispinosus Shen, 1957 reported by Lin et al. (1994) from the cultured sea bream Acanthopagrus schlegeli is a misidentification for C. rotundigenitalis Yü, 1933.

Development of brain injury in mice by Angiostrongylus cantonensis infection is associated with the induction of transcription factor NF-kappaB, nuclear protooncogenes, and protein tyrosine phosphorylation

Eosinophilic meningitis or meningoencephalitis caused by Angiostrongylus cantonensis is endemic to the Pacific area of Asia, especially Taiwan, Thailand, and Japan. Although eosinophilia is an important clinical manifestation of A. cantonensis infection, the role of eosinophils in the progress of the infection remains to be elucidated. In this experiment, we showed that A. cantonensis-caused eosinoplia and inflammation might lead to the induction of NF-kappaB and protooncogene expression via activation of the tyrosine phosphorylation signal pathway. After mice were infected daily with 30 third-stage larvae of A. cantonensis by oral adminstration for 6 weeks, no significant differences PKC-alpha, MEK-1, ERK-2, JNK, and p38 protein expression were found between the control and infected mice. However, the protein tyrosine phosphorylation levels, NF-kappaB, and iNOS protein products were significantly increased by 3.5-, 3.3-, and 6.3-fold, respectively, after 3 weeks of A. cantonensis infection. The same pattern was found for c-Myc, c-Jun, and c-Fos proteins, which were elevated by 3.2-, 2.3-, and 3.4-fold, respectively, compared to control animals after 3 weeks. The expression potency of these proteins started increasing in week 1, reaching maximal induction in week 3, and then declining in week 5 after A. cantonensis infection. Another consistent result was noted in the pathological observations, including eosinophilia, leukocyte infiltration, granulomatous reactions, and time responses in brain tissues of infected mice. These data suggest that the development of brain injury by eosinophlia of A. cantonensis infection is associated with NF-kappaB and/or nuclear protooncogenes expression, which is activated by the tyrosine phosphorylation pathway.

Minimal blood loss living donor hepatectomy

BACKGROUND

Donor hepatectomy with maximal safety while preserving graft viability is of principal concern in living donor liver transplantation. There are compelling reasons for avoiding blood transfusion, even with autologous blood, to avoid the potential risks it imposes on healthy donors. This study aims to describe the surgical technique and clinical outcomes of living donor hepatectomy with minimal blood loss requiring no blood transfusion.

METHODS

Donor hepatectomy was performed in 30 living donors according to a detailed preoperative imaging study of the vascular and biliary anatomy. Liver parenchymal transection was carried out with strict adherence to a meticulous surgical technique without vascular inflow occlusion to either side of the liver. Pre-, intra-, and postoperative data were gathered, and factors related to blood loss were analyzed retrospectively.

RESULTS

The intraoperative blood loss ranged from 20 to 300 ml with a mean of 72.0+/-58.9 ml (median, 55 ml), and neither homologous nor autologous blood transfusion was required in any of the donors intra- and postoperatively. All 30 donors were discharged with minimal complications, and remain well at a mean follow-up of 24 months after donation. Excellent graft viability was verified by the fact that all 30 recipients are alive and well with a few manageable complications. The actual graft and patient survival are both 100% at the time of writing.

CONCLUSIONS

Regardless of the extent of donor hepatectomy, blood loss can and should be kept to a minimum, and living donor hepatectomy without blood transfusion is a realistic objective.

Clusterin may be involved in rat liver allograft tolerance

Little is known about the possible role of complement inhibitors on tolerance induced by liver allografts. Clusterin, which is a plasma glycoprotein, inhibits cytolytic membrane attack complex (MAC) of complement by binding to soluble C5b-7 complex. The role of clusterin in relation to the naturally achieved tolerance in a rat orthotopic liver transplantation (OLT) has not been investigated before. Here we determined the kinetics of clusterin expression at different post-transplantation time points in a tolerogenic model (DA-PVG) where rejection was naturally overcome without any immunosuppressive drugs in comparison with the syngenic OLT model (DA-DA). Peripheral blood and liver tissues were taken from OLT at various post-operative time points. A strong expression of soluble clusterin was observed on post-transplantation day 7, which occurred at the peak of the rejection in this tolerogenic OLT model. The expression of clusterin remained strong even after tolerance was achieved. The intensity of clusterin expression was much stronger when compared with the syngenic OLT (DA-DA) model after OLT. A strong expression of clusterin mRNA was also observed in the tolerogenic model on post-OLT day (POD) 7 and the expression persisted when compared with the syngenic model on post-OLT day 60. Our data have shown that the strongest levels of clusterin during the reaction phase in tolerogenic OLT may be involved in tolerance induction.

Repeated hypotensive episodes due to hepatic outflow obstruction during liver transplantation in adult patients

We report two cases of unusual repeated hypotension, decreased cardiac output, decreased mixed venous oxygen saturation, decreased central venous pressure, pulmonary artery pressure, and pulmonary wedge pressure after the completion of all vascular anastamoses of liver transplantation. These unstable hemodynamics appear to reflect a clinically relevant picture of hypovolemia. However, the real cause was partial hepatic outflow obstruction. The obstruction was suspected because hypotension was alleviated by elevating the full-sized liver graft ventrally and to the left. Doppler ultrasound examination confirmed that the flow velocity of the hepatic vein outflow was insufficient when the liver fell to its resting position in the right hepatic fossa. An additional side-to-side cavo-caval anastomosis resolved the problem in one patient, whereas the other required not only the additional anastomosis, but also application of a tissue expander filled with 770 mL normal saline beneath the liver to eliminate the obstruction. We emphasize that obstruction of the hepatic outflow causes only temporal hypovolemia because of a decrease of venous return and that treatment of this complication should be surgical intervention to relieve the obstruction. Blind resuscitation with fluids will not solve the problem and, in fact, may result in fluid overload with subsequent complications.

Vaccinia virus envelope H3L protein binds to cell surface heparan sulfate and is important for intracellular mature virion morphogenesis and virus infection in vitro and in vivo

An immunodominant antigen, p35, is expressed on the envelope of intracellular mature virions (IMV) of vaccinia virus. p35 is encoded by the viral late gene H3L, but its role in the virus life cycle is not known. This report demonstrates that soluble H3L protein binds to heparan sulfate on the cell surface and competes with the binding of vaccinia virus, indicating a role for H3L protein in IMV adsorption to mammalian cells. A mutant virus defective in expression of H3L (H3L(-)) was constructed; the mutant virus has a small plaque phenotype and 10-fold lower IMV and extracellular enveloped virion titers than the wild-type virus. Virion morphogenesis is severely blocked and intermediate viral structures such as viral factories and crescents accumulate in cells infected with the H3L(-) mutant virus. IMV from the H3L(-) mutant virus are somewhat altered and less infectious than wild-type virions. However, cells infected by the mutant virus form multinucleated syncytia after low pH treatment, suggesting that H3L protein is not required for cell fusion. Mice inoculated intranasally with wild-type virus show high mortality and severe weight loss, whereas mice infected with H3L(-) mutant virus survive and recover faster, indicating that inactivation of the H3L gene attenuates virus virulence in vivo. In summary, these data indicate that H3L protein mediates vaccinia virus adsorption to cell surface heparan sulfate and is important for vaccinia virus infection in vitro and in vivo. In addition, H3L protein plays a role in virion assembly.

Telomerase activity in rat liver allografts

BACKGROUND

Telomerase activity in grafts may be involved in the alteration of cellular senescence after transplantation or its relevant immunological events.

METHODS

At the age of 20 weeks, donor livers harvested from DA (RT1a) were orthotopically transplanted into PVG (RT1c) or LEW (RT1(1)) rats. Rats having undergone orthotopic liver transplantation (OLT; DA-PVG) naturally overcome rejection, whereas all OLT (DA-LEW) rats die from acute rejection within 14 days. Telomerase activity in liver allografts was measured at various intervals post OLT.

RESULTS

At day 7 when the most severe rejection episode was observed in OLT (DA-LEW) and OLT (DA-PVG), the telomerase activity was significantly higher than in syngeneic OLT (DA-DA) rats, in which no rejection occurred. Telomerase activity in tolerogenic OLT (DA-PVG) livers remained elevated for at least 2 months.

CONCLUSION

These results suggest that telomerase activity in allogeneic OLT livers may reflect regenerating hepatocytes or activation of lymphocytes and/or hematopoietic stem cells associated with rejection or tolerance.

A novel speech controller for radio amateurs with a vision impairment

This paper describes a portable speech controller system for persons with a vision impairment to adjust the channel frequency of a radio set via speech commands. The speech commands are recognized on a general-purpose digital signal processor using a hidden Markov model (HMM), and are used to remotely control radio channel changes.

Molecular analysis of Duffy, Yt and Colton blood groups in Taiwanese, Filipinos and Thais

We used a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method for DNA-based typing of Duffy, Yt and Colton blood groups in Taiwanese, Filipinos and Thais. A total of 200 Taiwanese, 115 Filipinos and 105 Thais were studied. In the Duffy blood group in Taiwanese, 180 cases (90%) were homozygote of Fya, 18 cases (9%) were double heterozygote of Fya and Fyb, and 2 cases (1%) were homozygote of Fyb. In Filipinos, 98 cases (85.2%) were homozygote of Fya, 16 cases (14.0%) were double heterozygote of Fya and Fyb and 1 case (0.8%) was homozygote of Fyb. In Thais, 87 cases (82.9%) were homozygote of Fya, 18 cases (17.1%) were double heterozygote of Fya and Fyb, and no case of Fyb was found. These results correlate well with serological phenotype. For the Yt blood group, only YT1 was found in Taiwanese. Among Filipinos, 114/115 (99.1%) was YT1/1 and 1/115 (0.9%) was YT1/2. In Thais, 103/105 (98.1%) was YT1/1 and 2/105 (1.9%) was YT1/2. For the Colton blood group, the results showed that there was only Coa allele in these three populations. Our results provide the first data of the Yt and Colton blood groups in these three populations.

Obstructive hypertrophic cardiomyopathy in Taiwanese adults

The purpose of this study was to analyze the clinical profiles, echocardiographic findings, and mortality among adult Taiwanese patients with obstructive hypertrophic cardiomyopathy (HCM) at Chang Gung Memorial Hospital, a university-affiliated tertiary referral center in suburban Taipei. We reviewed the medical records of all adult (> 15 years of age) patients referred to our laboratory for echocardiographic examinations of cardiac diseases from May 1990 through December 1996. The diagnosis of obstructive HCM required an outflow gradient of above 10 mm Hg and the presence of asymmetric septal hypertrophy of the left ventricle. Follow-up information on was obtained from hospital records, questionnaires, interviews, or the National Death Certificate Registry. Of the 6.798 adults who underwent echocardiographic examinations during the study period 122 (1.79%) had obstructive HCM. The mean +/- standard deviation age of the patients was 62.2 +/- 12.6 years, and females predominated (n = 76, 62.3%). During the mean follow-up period of 3.2 years, the annual all-cause mortality rate was 4.7%. Most deaths were due to concurrent medical conditions. The annual cardiac mortality rate was 0.99%. Logistic regression analysis identified medication with calcium channel blockers as the only negative predictor (relative risk = 0.26, 95% confidence interval = 0.07-0.96) of all-cause mortality, and left atrial size as the only positive predictor (relative risk = 1.18, 95% confidence interval = 1.02-1.37) of cardiac mortality. Cox regression analysis confirmed the former association, but not the latter. Thus, in our institution, obstructive HCM had a low prevalence among adult patients referred for echocardiographic examination. These patients were elderly and often had other associated medical conditions. The high all-cause mortality rate was largely due to non-cardiac causes. These findings suggest that obstructive HCM tends to have a benign clinical course. Large atrial size could be an independent predictor of cardiac mortality, but this possibility requires further confirmation.

Reentrant tachyarrhythmias in right atria of cardiomyopathic versus healthy Syrian hamster

We studied the role of acetylcholine (ACh) and calcium overload in the induction of atrial flutter or atrial fibrillation (AF) in right atria from 34 normal male Syrian hamsters (F1B) and 33 cardiomyopathic Syrian hamsters (BIO 14.6) associated with focal myocardial necrosis. Action potential (AP) was recorded with conventional microelectrode techniques and twitch force by a transducer. ACh (0.1, 1 and 10 microM) induced high-frequency AF (around 33 Hz) along with tension oscillations and contracture in 7 of 12 normal hamster atria. These effects of ACh were abolished by tetrodotoxin or quinidine as well as by atropine. In contrast, ACh induced AF only in 1 of 12 myopathic atria. In both normal and myopathic atria, ACh induced similar changes in AP duration, spontaneous rate and force. The effects of calcium overload were tested by means of a high [Ca(2+)](o) (8.1 mM) low [K(+)](o) (1 mM) solution in another series of experiments. This solution also induced incidence of AF higher in normal (10/12) than in myopathic atria (4/12). The calcium load was also increased by high-frequency pacing (32 Hz for 3 or 30 s): AF occurred in normal atria (5/8), but not in myopathic atria (0/8). Measurement of the refractory period revealed a longer refractory period in myopathic than in control atria. We concluded that the lower incidence of AF in myopathic atria was probably due to their longer refractory period and the associated focal myocardial necrosis which then hindered the establishment of such a reentrant rhythm.

Gender differences in the presentation of adult obstructive hypertrophic cardiomyopathy with resting gradient: a study of 122 patients

The present study investigated gender differences among adult patients with obstructive hypertrophic cardiomyopathy (OHCM) and resting gradient. Using outflow gradients >10 mmHg and the presence of asymmetrical septal hypertrophy of the left ventricle as inclusion criteria, 122 patients were identified among patients referred for echocardiographic examinations between May 1990 and October 1996. Clinical, echocardiographical and follow-up data were compared between male and female patients. The female patients were significantly older than male patients (mean age +/-SD 66.7+/-10.5 vs 54.8+/-12.5 years). The female patients had a smaller interventricular septal wall thickness, less frequent systolic anterior movement of the mitral valve, more frequent association with hypertension, and less frequent association with ischemic heart disease (IHD) and giant T wave inversion. In this study population, adult female patients presented with OHCM 12 years later than males. Whether this represents female patients' reluctance to seek medical attention early, a different disease process that affects predominantly elderly females, or a gender-specific end organ response to aging, hypertension, IHD and other processes, or the protective effects of estrogen remains to be determined.

The fas and fas ligand pathways in liver allograft tolerance

The Fas and Fas ligand (Fas/FasL) pathways may play a central role in cytotoxicity or immunoregulation in liver transplantation. Here, in an attempt to examine the role of Fas/FasL on drug-free tolerance, we measured mRNA levels of Fas/FasL in livers by reverse transcriptase-polymerase chain reaction (RT-PCR), and also protein levels of Fas/FasL in livers by immunohistochemistry and in serum by dot blot assay. PVG recipients bearing DA livers showed serious rejection between post-operative (POD) days 7 and 14, but this rejection was naturally overcome without any immunosuppression. Fas gene and protein products were expressed on almost every cell in livers taken from naive rats, and at any time point in both syngeneic and allogeneic orthotopic liver transplantation (OLT) rats. In contrast, FasL mRNA in DA livers was detectable at POD 2, peaked at POD 14, and declined at POD 63 in allogeneic OLT (DA-PVG). Although the FasL gene was detectable in isografts at POD 14, its expression was much lower than in allografts. The time course and localization of FasL expression indicated that the expression of FasL gradually switched from infiltrating cells to hepatocytes when the rejection was naturally overcome and tolerance was induced in this OLT model. Soluble Fas could constitutively be detected at any time point in the serum of the tolerogenic OLT (DA-PVG) rats and was not diminished during the rejection phase. Soluble FasL peaked at POD 14 in allogeneic OLT, while sFasL was significantly lower in the serum of normal and syngeneic OLT rats. These findings suggest that the Fas and FasL pathways, including soluble forms, may contribute to the control of the immune response in this drug-free tolerance OLT model.

Cardiogenic shock in a patient with glyphosate-surfactant poisoning

We present a case of glyphosate-induced cardiogenic shock in a young man. The patient a 26-year-old man, presented with nausea and vomiting 4 hours after attempting suicide by drinking 150 mL of glyphosate surfactant. Cardiogenic shock with accelerated idio-ventricular rhythm on electrocardiography developed after admission. Intravenous injection of epinephrine, atropine, and calcium failed to improve the condition. Over the next 16 hours, the QRS complex gradually narrowed, sinus rhythm returned, and the hemodynamic status improved. Echocardiograms revealed diffuse left ventricular hypokinesis with markedly reduced ejection fraction while the patient was in shock; normal left ventricular function resumed the next day. In this case, the glyphosate surfactant poisoning-induced shock may have been due to transient suppression of the cardiac conduction system and contractility, rather than intravascular hypovolemia.

Prognosis of spontaneous intracerebral hemorrhage in hemodialysis patients

During an 8-year period, 32 consecutive patients with chronic renal failure on maintenance hemodialysis were diagnosed to have cerebral hemorrhage. The outcome was determined using the activity of daily life (ADL) at 6 months after hemorrhage. The overall mortality was 64%. Of the 12 surviving patients, no one made a good recovery (back to normality), 5 recovered to ADL grade II, 4 to grade III, 1 to grade IV, and 2 to grade V. Up to 91% of the patients had a history of hypertension. On admission, Glasgow coma scale (GCS) was 15 in 8 cases, 8-14 in 10, and below 8 in 14. The poor prognostic factors showing statistical significance included a poor admission GCS, age above 65 years, and blood sugar level of more than 200 mg/dl. Other factors which apparently were not related to the outcome included sex, history of stroke, acute myocardial infarction, hypertension, and diabetes mellitus, the locations of hemorrhage, the duration of hemodialysis, treatment modality (surgery vs non-surgery), and the laboratory data (blood urea nitrogen, creatinine, platelet count, hemoglobin, prothromin time, and partial thromboplastin time). This study confirmed a poor prognosis for hemodialysis patients with cerebral hemorrhage. More attention should be paid to the control of blood sugar in this group to improve the outcome of cerebral hemorrhage in hemodialysis patients, especially in elderly patients with poor admission GCS.

Automatic finite element mesh generation for maxillary second premolar

Developing three dimensional finite element mesh models for irregular geometric objects requires a large amount of manual efforts, hence limiting the three dimensional approach for dental structure analyses. An automatic procedure which can be used to generate a three dimensional finite element mesh for the maxillary second premolar was developed in this study. Firstly, a embedded second premolar was sliced and scanned parallel to the occlusal surface. A self-developed image processing system was employed to detect the boundaries of different materials within each section. An automatic mesh generation program was used on these boundaries to create tetrahedral elements based on moving nodes of uniform cube approach. Six mesh models of the second premolar with different element sizes using linear and quadratic elements were analyzed. Strain energy and von Mises stresses were reviewed for convergence in the crown regions.

Attenuation of basilar artery spasm after experimental subarachnoid hemorrhage in rabbit by potassium channel activator cromakalim--a preliminary result

Cerebral vasospasm associated with aneurysmal subarachnoid hemorrhage (SAH) remains a major complication in patients suffering from SAH. Regulation of membrane potential of arterial smooth muscle through activation or inhibition of potassium (K+) channel activity provides an important mechanism to dilate or constrict arteries. The present study examined the effect of a K+ channel activator, cromakalim, on cerebral vasospasm following experimental SAH. By the route of topical application and intra-arterial injection, basilar arteries were exposed transclivally and measured on-line using videomicroscopic camera. Continuous microinjection from right vertebral artery was given after the result of application was observed. Basilar artery spasm induced by SAH was released by topical or intra-arterial administration of cromakalim, and this beneficial effect against cerebral vasospasm was dose-dependent. There was no significant difference between topical and intra-arterial administration of cromakalim. These results indicate that K+ channel activator may play an important role for ameliorating cerebral vasospasm. An important goal of future studies will be to carefully evaluate the possibility and effect of intra-arterial administration of cromakalim to treat angiographic vasospasm.

Morphological alterations associated with the cytotoxic and cytostatic effects of citric acid on cultured human dental pulp cells

Citric acid exerts potential harmful effects on the pulp when used for root surface demineralization, smear layer removal, and dentin etching. Using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, we found that incubation of cultured human dental pulp cells in medium containing 0.5% (pH 4.74) or 1.0% (pH 3.42) of citric acid for 2 h lead to 25% and 48% of cell death, respectively. Cytotoxicity of citric acid was associated with its acidity. Exposure of cells to pure 1% citric acid (pH 2.26) for 60 s lead to immediate cell death. Cytotoxicity was usually preceded by cell retraction, cell surface blebbing, and finally uptake of trypan blue, implicating the presence of cell membrane damage. A medium containing 0.05% citric acid can retard the growth of pulp cells. These results indicate that adequate protection of the pulp is important, especially when the remaining dentin is thin in deep carious lesions or in the presence of accessory canals on the root surface.