Evaluation of functional changes in the medial temporal region during intracarotid amobarbital procedure by use of SPECT

PURPOSE

Because the main blood supply to the medial temporal region is through the posterior cerebral artery, the validity of the intracarotid amobarbital procedure (IAP) is still debated. To verify clinical validity of the IAP, we investigated changes in neuronal function in the medial temporal region during IAP.

METHODS

Brain single photon emission computed tomography (SPECT) was performed during IAP (IAP-SPECT) in 22 patients with temporal lobe epilepsy (TLE), and regional cerebral blood flow (rCBF) in the medial and lateral temporal regions of interest (ROIs) was measured quantitatively. To determine the distribution of sodium amobarbital, in another 20 patients with TLE, SPECT images were obtained after intracarotid injection of 99mTc-HMPAO mixed with sodium amobarbital.

RESULTS

Mean rCBF was 89.2% in the medial temporal region and 81.6% in the lateral temporal region: in the former region, it was significantly lower than that shown by the results of interictal SPECT (99.1%; p < 0.001). In a few patients, however, rCBF did not decrease in the medial temporal region. In only 25% of patients, the medial temporal region was visualized in SPECT images obtained after intracarotid injection of 99mTc-HMPAO.

CONCLUSIONS

The results in this study demonstrate that IAP is valid because the medial temporal region is inactivated in spite of infrequent delivery of sodium amobarbital. We assume that intratemporal diaschisis is operating for the inactivation of neuronal function. IAP-SPECT with intratemporal ROIs may be useful for monitoring changes in neuronal function in the medial temporal region during IAP.

Effect of cross-link density and hydrophilicity of PU on blood compatibility of hydrophobic PS/hydrophilic PU IPNs

To investigate the effect of the hydrophilic and hydrophobic microdomain structure on blood compatibility, a series of interpenetrating polymer networks (IPNs) composed of hydrophilic polyurethane (PU) and hydrophobic polystyrene (PS) was prepared. One series was prepared with varying cross-link densities of each network, the other with varying hydrophilicity of the PU component. All PU/PS IPNs exhibited microphase-separated structures that had dispersed PS domains in the continuous PU matrix. The domain size decreased with decreasing the hydrophilicity of the PU component and increasing the cross-link density of each network. As the cross-link density and hydrophobicity of the PU component was increased, an inward shift of Tgs was observed, which was due to the decrease in phase separation between the hydrophobic PS component and hydrophilic PU component. In the in vitro platelet adhesion test, as the microdomain size of PU/PS IPN surface decreased, the number of adhered platelets on the PU/PS IPN surface was reduced and deformation of the adhered platelets decreased. It could be concluded that blood compatibility of PU/PS IPN was mainly affected by the degree of mixing between PU and PS component, which was reflected by the domain size of PS rich phase.

Vaccination with a recombinant vaccinia virus encoding a "self" antigen induces autoimmune vitiligo and tumor cell destruction in mice: requirement for CD4(+) T lymphocytes

Many human and mouse tumor antigens are normal, nonmutated tissue differentiation antigens. Consequently, immunization with these "self" antigens could induce autoimmunity. When we tried to induce immune responses to five mouse melanocyte differentiation antigens, gp100, MART-1, tyrosinase, and tyrosinase-related proteins (TRP) 1 and TRP-2, we observed striking depigmentation and melanocyte destruction only in the skin of mice inoculated with a vaccinia virus encoding mouse TRP-1. These mice rejected a lethal challenge of B16 melanoma, indicating the immune response against TRP-1 could destroy both normal and malignant melanocytes. Cytotoxic T lymphocytes specific for TRP-1 could not be detected in depigmented mice, but high titers of IgG anti-TRP-1 antibodies were present. Experiments with knockout mice revealed an absolute dependence on major histocompatibility complex class II, but not major histocompatibility complex class I, for the induction of both vitiligo and tumor protection. Together, these results suggest that the deliberate induction of self-reactivity using a recombinant viral vector can lead to tumor destruction, and that in this model, CD4(+) T lymphocytes are an integral part of this process. Vaccine strategies targeting tissue differentiation antigens may be valuable in cancers arising from nonessential cells and organs such as melanocytes, prostate, testis, breast, and ovary.

The evening tea break ritual--a case study

Many nursing scholars, such as Carter (1990), Ford and Walsh (1994), Huey (1986), James (1990), Thomlinson (1990), Larson (1987), Rush et al (1990), Spiller (1992), Street (1990a,b; 1992a,b,c,d), Lawrence (1996), Walker (1967), Walsh and Ford (1989 a,b,c,d; 1991 a,b), have examined the effects of rituals in nursing practice, and have argued for a need to scrutinise these ritual practices because of their negative effect on patients. Other scholars, such as Holland (1993) and Biley and Wright (1997), have argued that these rituals have meanings for nurses. Street (1992c) has argued that rituals are resilient in nursing practice. In order to identify the factors that contribute to rituals' resilience, there is a need to understand their meanings and effects on nurses, and how nurses keep them alive. This study has explored the meanings of the 'evening tea break' ritual to a group of nurses in a medical ward. The study has employed an ethnographic approach, and has found that the evening tea break ritual had affective effects on the participating nurses. It provides the time, space, the process and the environment for nurses to ventilate their feelings, to gain support from each other.

Biochemical characterization of a UDP-sugar pyrophosphorylase from Thermus caldophilus GK24

An extremely thermostable UDP-GlcNAc pyrophosphorylase has been purified from Thermus caldophilus GK24 by chromatographic methods including ion-exchange, hydrophobic interaction, and affinity chromatographies. The specific activity of the enzyme was enriched 41.8-fold, with a recovery of 2%. The molecular mass of the enzyme was 41 kDa by SDS/PAGE and 45 kDa by gel-filtration chromatography. The activity was maximum at 86 degrees C and its half-life at 95 degrees C was 30 min. Its optimum pH was 6.9 in the presence of Mg2+ ions. A biochemical study showed that UDP-GlcNAc pyrophosphorylase activity could be enhanced by fructose 1-phosphate, a precursor of UDP-GlcNAc. The enzyme showed a broad substrate specificity with sugar 1-phosphates, including glucose 1-phosphate, GlcNAc-1-P and xylose 1-phosphate. The enzyme was therefore named UDP-sugar pyrophosphorylase. The N-terminal and internal peptide sequences were determined and compared with known sequences from various sources. It was found that N-terminal sequence is similar to that of UDP-GlcNAc and UDP-glucose pyrophosphorylases from other bacterial sources.

Mechanisms related to [18F]fluorodeoxyglucose uptake of human colon cancers transplanted in nude mice

[18F]Fluorodeoxyglucose ([18F]FDG), a glucose analogue, has been widely used for tumor imaging. To investigate the mechanisms related to [18F]FDG uptake by tumors, an experiment involving nude mice was performed.

METHODS

Human colon cancer cell lines SNU-C2A, SNU-C4 and SNU-C5 were transplanted to nude mice. Using immunohistochemical staining and Western blot, the expression of glucose transporter (Glut) isoforms (Glut-1 through -5) in xenografted tumors was analyzed. For the analysis of messenger ribonucleic acid (mRNA) expression, reverse-transcription polymerase chain reaction and Northern blot were used and the enzyme activity of hexokinase in cancer tissues was measured by continuous spectrophotometric rate determination.

RESULTS

[18F]FDG uptake in SNU-C4 and SNU-C5 cells was higher than in normal colon cells. Among these cells and xenografted tumors, SNU-C5 showed the highest level of [18F]FDG uptake, followed by SNU-C4 and SNU-C2A. An immunostaining experiment showed intense staining of Glut-1 in SNU-C5 tumors but somewhat faint staining in SNU-C4. SNU-C5 tumors also showed positive staining with Glut-3, although this was not the case with SNU-C2A and SNU-C4. Western blot analysis showed the expression of Glut-1 and Glut-3 in all tumors. Experiments involving Northern blot analysis and reverse-transcription polymerase chain reaction confirmed the overexpression of Glut-1 mRNA in all tumors, with the highest level in SNU-C5. The level of Glut-3 mRNA was also elevated in SNU-C5 tumors but not in SNU-C2A and SNU-C4. The enzyme activity of hexokinase did not vary among different tumors.

CONCLUSION

Gluts, especially Glut-1, are responsible for [18F]FDG uptake in a nude mouse model of colon cancer rather than hexokinase activity. Increased numbers of glucose transporters at the plasma membrane of cancer cells is attributed to an increased level of transcripts of glucose transporter genes and may be a cause of increased [18F]FDG uptake, at least in colon cancer tumors.

Purification and characterization of N-Acetylglucosamine 6-phosphate deacetylase from Thermus caldophilus

N-Acetylglucosamine 6-phosphate deacetylase [EC 3.5.1.25] was purified and biochemically characterized from an extreme thermophile, Thermus caldophilus GK24. The optimum temperature and pH of the enzyme were 80 degrees C and 7.5, respectively. The enzyme is a tetramer composed of identical 45 kDa subunits. The N-terminal amino acid sequence of the purified enzyme was determined to be MSVDLKTLHRRHVLTP. It hydrolyzed GlcNAc-6-P, but not GlcNAc-1-P or chitin oligosaccharides. The deacetylase activity was completely inhibited by the addition of 1 mM Cu2+, but moderately activated by that of 1 mM Mn2+ and Co2+. Within 2 h of reaction, 2 mM GlcNAc-6-P was completely hydrolyzed to GlcN-6-P and acetate by the action of the deacetylase.

A thermostable xylose isomerase from Thermus caldophilus: biochemical characterization, crystallization and preliminary X-ray analysis

A highly thermostable xylose isomerase from Thermus caldophilus has been expressed in Escherichia coli. The purified enzyme has an optimum temperature of 363 K. It has been crystallized at room temperature using ammonium sulfate as a precipitant. The crystal belongs to the orthorhombic space group P212121, with unit-cell parameters a = 84.35, b = 123.60, c = 140.24 A. The presence of one molecule of tetrameric xylose isomerase in the asymmetric unit gives a crystal volume per protein mass (Vm) of 2.1 A3 Da-1 and a solvent content of 41% by volume. The crystals initially showed diffraction to 1.7 A Bragg spacing with synchrotron X-rays, and a set of native data extending to 2.3 A resolution has been collected.

Thymic selection by a single MHC/peptide ligand: autoreactive T cells are low-affinity cells

In H2-M- mice, the presence of a single peptide, CLIP, bound to MHC class II molecules generates a diverse repertoire of CD4+ cells. In these mice, typical self-peptides are not bound to class II molecules, with the result that a very high proportion of H2-M- CD4+ cells are responsive to the various peptides displayed on normal MHC-compatible APC. We show here, however, that such "self" reactivity is controlled by low-affinity CD4+ cells. These cells give spectacularly high proliferative responses but are virtually unreactive in certain other assays, e.g., skin graft rejection; responses to MHC alloantigens, by contrast, are intense in all assays. Possible explanations for why thymic selection directed to a single peptide curtails self specificity without affecting alloreactivity are discussed.

Topoisomerase I inhibitors from the Streptomyces sp. strain KM86-9B isolated from a marine sponge

The crude extract of Streptomyces sp. strain KM86-9B, isolated from a marine sponge, displayed significant inhibition on topoisomerase I activity. Investigation of the causative components by bioactivity-directed fractionation resulted in the isolation of a series of iso- and anteiso-fatty acids.

Bone scan appearance of renal osteodystrophy in diabetic chronic renal failure patients

To investigate Tc-99m methylenediphosphonate (MDP) bone scan appearance in diabetic chronic renal failure patients, we compared the bone scan images of chronic renal failure patients with and without diabetes. The number of patients studied was 134, of whom 43 had diabetes. Two nuclear medicine physicians read Tc-99m MDP bone scan images and for six areas - the axial skeleton, long bone, skull and mandible, periarticular areas, costochondral junction, and sternum - assigned a score of either 1 or 0. The sums of scores were compared. We also performed multivariate analysis including sex, age, and serum creatinine level using analysis of covariance. DM group patients scored significantly lower (2.01+/-0.95) than those of the non-DM group (3.26+/-1.16). Analysis of covariance revealed that the lower DM group score was independent of sex, age, and serum creatinine level. The bone scans of diabetic chronic renal failure patients showed less Tc-99m MDP uptake than those of non-diabetic patients. Thus, diagnosing renal osteodystrophy in diabetic chronic renal failure patients on bone scan images could be difficult.

Whole-body [18F]FDG PET in the management of metastatic brain tumours

BACKGROUND

To determine its roles in the diagnosis and the systemic evaluation of metastatic brain tumours, whole-body positron emission tomography (PET) using [18F]FDG was performed in 20 consecutive patients.

METHODS

All patients were thought to be suffering or needing to be differentiated from metastatic brain tumours. Nine patients had multiple brain lesions; six were older and showed a rim-enhancing lesion with surrounding oedema; seven had homogeneously enhancing periventricular lesion(s) on computed tomography (CT) and/or magnetic resonance (MR) imaging, thought to be central nervous system lymphomas. Two patients had skull mass(es) and two patients had a solid mass suspected to be, respectively, a haemorrhagic metastasis and a metastatic malignant melanoma. All of them received whole-body [18F]FDG PET and conventional systemic work-up for metastasis in order to compare the results of the two methods.

RESULTS

Metastatic brain tumours were diagnosed on whole-body [18F]FDG PET in eleven patients who had extracranial and intracranial hypermetabolic lesions. In nine of these, a conventional work-up also detected primary lesions which on whole-body [18F]FDG PET were seen to be hypermetabolic foci. Systemic lymph node metastases were detected by whole-body [18F]FDG PET only in two patients and histological diagnosis was possible by biopsy of lymph nodes rather than of brain lesions. In the remaining nine patients who had only intracranial hypermetabolic foci, histological diagnosis was made by craniotomy or stereotactic biopsy. It was confirmed that seven of nine patients were suffering from a primary brain tumour and two from metastatic carcinoma. None of the nine showed evidence of systemic cancer on conventional work-up. Histological diagnoses of the primary brain tumours were four cases of primary central nervous system lymphoma and one each of multifocal glioblastoma, Ewing's sarcoma, and cavernous angioma. Patients felt no discomfort during the whole-body [18F]FDG PET procedure and there were no complications. The false negative rate in [18F]FDG PET and in conventional work-up was 15.4% and 30.7% respectively. There were no false positives on either [18F]FDG PET or conventional work-up.

CONCLUSION

It is suggested that whole-body [18F]FDG PET is a safe, reliable, and convenient method for the diagnosis and systemic evaluation of patients thought to be suffering or needing to be differentiated from a metastatic brain tumour.

Phospholipid translocation from the outer to the inner leaflet of synaptic vesicle membranes isolated from the electric organ of Japanese electric ray Narke japonica

The phospholipid translocation from the outer to the inner leaflet of synaptic vesicles isolated from the electric organ of the Japanese electric ray, Narke japonica, was measured using fluorescent phospholipid probes. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), or phosphatidylserine (PS) with a fluorescent NBD-labeled short acyl chain at the sn-2 position was mixed with purified synaptic vesicles and the probe in the outer leaflet of the membranes was reduced with dithionite to quench the fluorescence from time to time. The percentage of fluorescence remaining after the dithionite treatment served as an index for the phospholipid translocation. The results obtained indicated that about 30, 13, and 9% of NBD-PE, NBD-PS, and NBD-PC, respectively, were translocated from the outer to the inner leaflet in 3 h. Thus, the translocation activity in synaptic vesicle membranes was much higher for PE than for PS, in contrast to the previous results obtained with plasma membranes, including synaptosomal membranes. The percentages of the phospholipid in the inner leaflet at equilibrium were estimated to be 41, 31, and 14% for PE, PS, and PC, respectively. The translocation was inhibited by pretreatment with an SH reagent, iodoacetamide, indicating the involvement of a proteinaceous translocator. These data may provide a biochemical basis for elucidating the mechanisms of membrane fusion and exocytosis at nerve endings.

Dopamine transporter imaging with [123I]-beta-CIT demonstrates presynaptic nigrostriatal dopaminergic damage in Wilson's disease

OBJECTIVES

The most common neurological manifestations in Wilson's disease are parkinsonism and dystonia. These are assumed to be due to striatal injury, which has been repeatedly demonstrated by pathology and CT or MRI. The substantia nigra has not been shown to be damaged in pathological studies. However, there have been clinical and imaging studies suggesting presynaptic nigrostriatal injury. (1r)-2Beta-carbomethoxy-3beta-(4-iodophenyl)tropane (beta-CIT) is a specific ligand that binds to the dopamine transporter (DAT), and can examine the integrity of dopaminergic nerve terminals. Evidence for presynaptic nigrostriatal dopaminergic damage in Wilson's disease was searched for using [123I]-beta-CIT SPECT.

METHODS

Six patients with Wilson's disease were studied, together with 15 healthy normal controls, and six patients with Parkinson's disease. After injection of [123I]-beta-CIT, SPECT studies were done at 18 hours. Specific striatal/occipital binding ratio (S/O ratio) was calculated as (striatal binding-occipital binding)/occipital binding.

RESULTS

The specific S/O ratios were 6.22 (1.32) (mean (SD)) in normal volunteers, 3.78 (0.65) in Parkinson's disease, and 3.60 (0.49) in Wilson's disease.

CONCLUSION

There was severe loss of the DAT in the striatum suggesting significant damage in presynaptic nigrostriatal dopaminergic nerve terminals. Therefore, a presynaptic lesion may contribute to neurological manifestations in Wilson's disease.

Prevalence of viral hepatitis markers in Korean patients with hepatocellular carcinoma

The positive rates of hepatitis B surface antigen (HBsAg) and antibody to hepatitis C virus (anti-HCV) were analyzed according to year, sex, age, and serum ALT levels in 1,370 patients with hepatocellular carcinoma (HCC) who visited the Korea Cancer Center Hospital between January 1989 and December 1994. The positive rate of HBsAg was 68.8 to 76.0% per year in patients with HCC, while that of anti-HCV was 3.2 to 9.8% per year. No sex predominance was found in the positive rates of HBsAg and anti-HCV. HBsAg positivity was distributed mostly in the 41 to 50 age group, whereas anti-HCV positivity was distributed mostly in the over 50 age group. Higher positive rate of anti-HCV was observed in HCC patients with serum ALT levels above the normal range than in those with serum ALT levels within the normal range. However, elevated serum ALT levels above the normal range was not related to the positive rate of HBsAg. The relatively low prevalence of anti-HCV in patients with HCC suggests that the role of HCV infection in the development of HCC lower than that of HBV infection in Korea. However, our results suggest that HCV is another potent risk factor for HCC even in HBV endemic areas.

Top DNA polymerase from Thermus thermophilus HB27: gene cloning, sequence determination, and physicochemical properties

A gene, top encoding Thermus thermophilus HB27 (Top) DNA polymerase, was cloned in E. coli and its nucleotide sequence was determined. Based on its deduced amino acid sequence, Top DNA polymerase is a 93.8 kDa protein comprising 834 amino acid residues. Top DNA polymerase showed high amino acid homology with those of other DNA polymerases from the Thermus sp., for example, 87.3% identity with Taq DNA polymerase. Codon usage in the top gene was similar to those of the proteins from other Thermus strains. The G + C content in the third position of the codons was as high as 93%. The top gene under the control of the tac promoter was expressed in E. coli [plasmid pTOP9]. DNA amplification using the recombinant Top DNA polymerase performed the same as other thermostable DNA polymerases from Thermus strains. The optimum temperature for its reaction was 76 degrees C. An interesting observation was that the recombinant Top DNA polymerase was slowly cleaved into two fragments of about 60 kDa and 35 kDa at 4 degrees C and -20 degrees C. The larger fragment possessed polymerase activity like the Klenow fragment of E. coli DNA polymerase I. To prevent the cleavage of the Top DNA polymerase, a variety of protecting agents were examined. Among those examined, (NH4)2SO4 (100 mM) solution demonstrated an outstanding ability to block its cleavage for a prolonged period.

Diagnostic value of positron emission tomography for detecting breast cancer

Positron emission tomography (PET) is an imaging method that employs radionuclide and tomography techniques. PET has high sensitivity for detecting breast cancer, both the primary tumor and axillary node metastasis. From June 1995 to November 1996 a total of 27 patients underwent breast operations based on PET results at Seoul National University Hospital. Whole-body PET images were obtained beginning 60 minutes after injection of 370 MBq (10 mCi) 18F-fluorodeoxyglucose. Regional scans were also obtained with transmission images. We compared the PET results with those from the physical examination and mammography. All cases were histologically confirmed. The diagnostic accuracy of PET was excellent for the primary tumor mass (97%) compared with that of the physical examination (78%) and mammography (67%). For axillary lymph node metastasis, PET had outstanding detection accuracy (96%) compared with the physical examination and mammography (74% and 60%, respectively). Whole-body PET scans made it possible to see all of the metastatic lesions at a glance in cases of metastatic or recurrent breast cancer. There was a probable correlation between the standard uptake value (SUV) and the number of axillary lymph node metastases, but in this study statistical significance was not proved because of the small number of cases. PET also could detect breast cancer in paraffin-augmented breasts. We concluded that PET is a highly sensitive, accurate diagnostic tool for breast cancer and that SUV, after more studies, could be used as an important prognostic factor.

Patterns of relapse and response to retreatment in patients with metastatic melanoma or renal cell carcinoma who responded to interleukin-2-based immunotherapy

PURPOSE

The purpose of this study was to examine the pattern of relapse and the treatment of relapse with either surgery or repeat immunotherapy in patients with metastatic melanoma or renal cell carcinoma who had previously responded to interleukin-2-based therapy.

PATIENTS AND METHODS

Over a 10-year period 1051 patients with metastatic melanoma or renal cell carcinoma were treated with interleukin-2-based immunotherapy at a single institution. One hundred fifty-nine patients who relapsed after an initial partial response or complete response to interleukin-2-based immunotherapy formed the study population for this retrospective review. Medical records, physical examination forms, and relevant radiographs were reviewed to determine response, relapse site(s), and response to treatment for relapse.

RESULTS

Relapse after an initial response to interleukin-2-based therapy occurred in 84 (80%) of 105 patients with metastatic melanoma and in 75 (70%) of 107 patients with metastatic renal cell carcinoma. Relapse after an initial partial response involved 71 (97%) of 73 patients with metastatic melanoma and 55 (86%) of 64 patients with metastatic renal cell carcinoma. The initial site(s) of relapse after a partial response involved a new site(s), old site(s), or both old and new sites with relatively even distribution. Relapse after an initial complete response occurred in 13 (41%) of 32 patients with metastatic melanoma and in 20 (47%) of 43 completely responding patients with metastatic renal cell carcinoma. Surprisingly, the initial site of relapse after a complete response involved only new sites of disease in 70% of patients. Retreatment of relapses with the same interleukin-2-based therapy originally used was effective in only one (2%) of 54 selected patients, but a different interleukin-2-based therapy in 35 patients resulted in five responders (a 14% secondary response rate). Most re-responders, however, responded to treatment with tumor-infiltrating lymphocytes and interleukin-2, and only one of 20 patients responded to retreatment with interleukin-2 alone. Surgical metastasectomy with therapeutic intent in 25 selected melanoma patients and in 31 selected renal cell cancer patients resulted in a 2-year progression-free survival of 18% in patients with metastatic melanoma and 37% in patients with metastatic renal cell carcinoma.

DISCUSSION

In patients with metastatic melanoma or renal cell carcinoma, tumor relapse was common after a partial response to an interleukin-2-based therapy and included previously identified sites of disease in most patients. Relapse after a complete response was less frequent and involved only new sites in a majority of patients. In selected patients who relapsed, repeat treatment with the same interleukin-2-based therapy that provided the initial response was rarely effective. However, with a different interleukin-2-based therapy, usually using tumor-infiltrating lymphocytes, repeat treatment induced secondary responses in some patients. In addition, salvage metastasectomy resulted in durable progression-free survival in selected patients.

cDNA isolation of Alzheimer's amyloid precursor protein from cholinergic nerve terminals of the electric organ of the electric ray

Alzheimer's amyloid precursor protein (APP) is a transmembrane protein containing three phosphorylation sites in its cytoplasmic domain. In the present study, we isolated cDNA of APP from electric ray electric lobe (elAPP). This APP (elAPP699) consists of 699 amino acids, contains the beta-amyloid domain and has 80.7% similarity with the human APP695 isoform. The cytoplasmic domain, including three phosphorylation sites, was completely conserved. In the nerve terminals of the cholinergic neuron from the electric ray electric organ, we found elAPP699 existed exclusively in the mature form. We found the phosphorylated form of mature elAPP699 in the nerve terminal as well as in cell body. Immature elAPP699 was not subject to phosphorylation. Our findings indicate that, in neurons, the phosphorylation of APP occurs after maturation.

Cauda equina syndrome after incidental total spinal anesthesia with 2% lidocaine

A 77 year-old male presented for a right popliteal distal vein bypass graft procedure with continuous epidural anesthesia and light general endotracheal anesthesia. After the uneventful placement of the epidural needle and catheter at the L2-L3 interspace, fentanyl 150 microg and a total of 72 ml of preservative-free 2% lidocaine with epinephrine was continually injected through the epidural catheter for the duration of the more than 5 hour procedure. At the end of the procedure, it was noted that the patient had developed total spinal anesthesia, and his pupils were fixed and dilated. Further examination confirmed that the catheter tip was placed in the subarachnoid space. The patient was unable to turn or sit up by himself for over 1 month. Over a 12-month period, he improved to walking with a quad cane, but he required self-catheterization. Although numerous factors were considered, neurotoxicity of 2% lidocaine solution has been discussed as the potential cause. We were unable to find any other factors that could have caused the cauda equina syndrome.

HCV and HBV coexist in HBsAg-negative patients with HCV viraemia: possibility of coinfection in these patients must be considered in HBV-high endemic area

Hepatocellular carcinoma (HCC) is one of the most common cancers and is highly associated with hepatitis B virus (HBV) infection in Korea. The role of HBV and hepatitis C virus (HCV) in HCC patients who are negative for hepatitis B surface antigens (HBsAg) remains poorly defined. It has been suggested that HCV core protein may impair the polymerase activity of HBV in vitro, potentially lowering HBV titre in coinfected patients. Therefore, routine enzyme immunoassay may not detect HBV, in spite of the presence of HBV viraemia in low titres. The aim of this study was to confirm the coexistence of HBV viraemia in hepatitis C-infected patients with HCC who have apparent HBsAg seronegativity and to establish the need for clinical reinterpretation of enzyme immunoassay (EIA) serological tests of HBsAg in patients with HCV viraemia and HCC. The serological profiles of HBV and HCV in 616 patients with HCC were analysed and the coinfection rate of HCV and HBV investigated. Sera were obtained from 16 patients who were both anti-HCV and HCV-RNA positive but HBsAg negative, and tested for HBV by polymerase chain reaction (PCR). Eleven non-A and non-B chronic hepatitis patients without HCC who had the same profiles of anti-HCV, HCV-RNA, and HBsAg were tested for HBV by PCR. As a control group, sera were obtained from 15 patients with HCC and 30 non-A and non-B chronic hepatitis patients without HCC; both were anti-HCV, HCV-RNA, and HBsAg negative and tested for HBV PCR. Of the 616 patients with HCC, 450 (73.1%) had current HBV infection, 48 (7.8%) had anti-HCV antibodies, and nine (1.5%) had viral markers of both HCV and HBV by serological profiles. Of the 27 patients with HCV viraemia and HBsAg seronegativity (16 with HCC; 11 with non-A non-B chronic hepatitis), 14 (51.9%) showed HBV viraemia by PCR. In contrast, of the 75 patients in the control group (45 with HCC; 30 with non-A and non-B chronic hepatitis) who were both HCV PCR negative and HBsAg negative, five (11.1%) showed HBV viraemia by PCR. The PCR for HBV revealed coexistent HBV viraemia in HCV viraemia patients, despite HBsAg negativity by EIA. In HBV-endemic areas, the possibility of coinfection of HBV in HBsAg-negative patients with HCV viraemia should be considered and molecular analysis for HBV-DNA performed.

Hepatitis C virus E2 protein purified from mammalian cells is frequently recognized by E2-specific antibodies in patient sera

The envelope protein of hepatitis C virus (HCV) is composed of two membrane-associated glycoproteins, E1 and E2. To obtain HCV E2 protein as a secretory form at a high level, we constructed a recombinant chinese hamster ovary (CHO) cell line expressing a C-terminal truncated E2 (E2t) fused to human growth hormone (hGH), CHO/hGHE2t. The hGHE2t fusion protein was purified from the culture supernatant using anti-hGH mAb affinity chromatography at approximately 80% purity. The purified hGHE2t protein appeared to be assembled into oligomers linked by intermolecular disulfide bond(s) when density gradient centrifugation and SDS-polyacrylamide gel electrophoresis were employed. When the purified fusion protein was used for testing its ability to bind to antibodies specific for HCV by enzyme-linked immunosorbent assay, the protein was recognized by antibodies in sera from 90% of HCV-positive patients. Treatment of hGHE2t protein by beta-mercaptoethanol, but not by heat and SDS, significantly reduced its reactivity to the antibodies of patient sera, suggesting that intermolecular and/or intramolecular disulfide bonds are important for its ability to recognize its specific antibody and that the E2 protein contains discontinuous antigenic epitope(s).

Mutagenesis of the positively charged conserved residues in the 5' exonuclease domain of Taq DNA polymerase

Taq DNA polymerase from Thermus aquaticus has been shown to be very useful in the polymerase chain reaction method. Taq DNA polymerase has a domain at the amino terminus (residue 1 to 290) that has a 5' exonuclease activity and a domain at the C-terminus that catalyzes polymerase reaction. Taq DNA polymerase is classified into the pol I family which is represented by E. coli DNA polymerase I. The alignment of amino acid sequences for the 5' exonuclease domains of the pol I family DNA polymerases shows six highly conserved sequences called motifs A to F. Motif C contains three positively charged residues such as 74Arg, 82Lys and 85Arg which might be involved in catalysis. In order to understand the function of those residues, they are mutagenized to alanine. The 5' exonucleolytic activities of those mutated 5' exonucleases decreased by 80 to 90%, thereby implying that three positively charged residues play certain roles in the 5' exonuclease catalysis.

Biodegradable block copolymers as injectable drug-delivery systems

Polymers that display a physicochemical response to stimuli are widely explored as potential drug-delivery systems. Stimuli studied to date include chemical substances and changes in temperature, pH and electric field. Homopolymers or copolymers of N-isopropylacrylamide and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (known as poloxamers) are typical examples of thermosensitive polymers, but their use in drug delivery is problematic because they are toxic and non-biodegradable. Biodegradable polymers used for drug delivery to date have mostly been in the form of injectable microspheres or implant systems, which require complicated fabrication processes using organic solvents. Such systems have the disadvantage that the use of organic solvents can cause denaturation when protein drugs are to be encapsulated. Furthermore, the solid form requires surgical insertion, which often results in tissue irritation and damage. Here we report the synthesis of a thermosensitive, biodegradable hydrogel consisting of blocks of poly(ethylene oxide) and poly(L-lactic acid). Aqueous solutions of these copolymers exhibit temperature-dependent reversible gel-sol transitions. The hydrogel can be loaded with bioactive molecules in an aqueous phase at an elevated temperature (around 45 degrees C), where they form a sol. In this form, the polymer is injectable. On subcutaneous injection and subsequent rapid cooling to body temperature, the loaded copolymer forms a gel that can act as a sustained-release matrix for drugs.