Transplantation of hNT neurons into the ischemic cortex: Cell survival and effect on sensorimotor behavior

Cell transplantation offers a potential new treatment for stroke. Animal studies using models that produce ischemic damage in both the striatum and the frontal cortex have shown beneficial effects when hNT cells (postmitotic immature neurons) were transplanted into the ischemic striatum. In this study, we investigated the effect of hNT cells in a model of stroke in which the striatum remains intact and damage is restricted to the cortex. hNT cells were transplanted into the ischemic cortex 1 week after stroke induced by distal middle cerebral artery occlusion (dMCAo). The cells exhibited robust survival at 4 weeks posttransplant even at the lesion border. hNT cells did not migrate, but they did extend long neurites into the surrounding parenchyma mainly through the white matter. Neurite extension was predominantly toward the lesion in ischemic animals but was bidirectional in uninjured animals. Extension of neurites through the cortex toward the lesion was also seen when there was some surviving cortical tissue between the graft and the infarct. Prolonged deficits were obtained in four tests of sensory-motor function. hNT-transplanted animals showed a significant improvement in functional recovery on one motor test, but there was no effect on the other three tests relative to control animals. Thus, despite clear evidence of graft survival and neurite extension, the functional benefit of hNT cells after ischemia is not guaranteed. Functional benefit could depend on other variables, such as infarct location, whether the cells mature, the behavioral tests employed, rehabilitation training, or as yet unidentified factors.

“Orthogonal” separations for reversed-phase liquid chromatography

A general procedure is proposed for the rapid development of a reversed-phase liquid chromatographic (RP-LC) separation that is "orthogonal" to a pre-existing ("primary") method for the RP-LC separation of a given sample. The procedure involves a change of the mobile-phase organic solvent (B-solvent), the replacement of the primary column by one of very different selectivity, and (only if necessary) a change in mobile phase pH or the use of a third column. Following the selection of the "orthogonal" B-solvent, column and mobile phase pH, further optimization of peak spacing and resolution can be achieved by varying separation temperature and either isocratic %B or gradient time. The relative "orthogonality" of the primary and "orthogonal" RP-LC methods is then evaluated from plots of retention for one method versus the other. The present procedure was used to develop "orthogonal" methods for nine routine RP-LC methods from six pharmaceutical analysis laboratories. The relative success of this approach can be judged from the results reported here.

A retrospective study evaluating single-unit red blood cell transfusions in reducing allogeneic blood exposure

Although guidelines recommend the use of single-unit red blood cell (RBC) transfusions to minimize allogeneic blood exposure, clinical practice remains dominated by two-unit transfusions. This study assesses the potential impact of a single-unit transfusion policy on reducing RBC utilization. We performed a retrospective analysis of adult patients admitted to a tertiary care hospital who received one or two RBC units. In subjects transfused two units, the effect of one unit was estimated by dividing the change in haemoglobin by 2. The proportion of patients reaching a haemoglobin threshold of 70, 75, 80, 85 and 90 g L(-1) with a single RBC unit was estimated. Of 302 included patients, only 65 received a one-unit transfusion. Based on thresholds of > or = 90, > or = 80 and > or = 70 g L(-1), a single-unit transfusion would be sufficient in 42.0% (RRR = 0.54), 79.6% (RRR = 0.23) and 98.0% (RRR = 0.02) of cases, respectively. This corresponds to 0.21, 0.57 and 0.82 mean RBC units saved per patient. In the orthopaedic subpopulation, the mean RBC units saved are 0.53, 0.88 and 1.00 for the same haemoglobin targets. Adopting a policy of transfusing RBC in single-unit aliquots could significantly improve RBC utilization and decrease patient exposure to allogeneic blood.

A prospective evaluation of health-related quality of life in Hong Kong Chinese patients with chronic non-cancer pain

OBJECTIVE

To evaluate the health-related quality of life in Hong Kong Chinese patients with chronic non-cancer pain.

DESIGN

Prospective cross-sectional survey.

SETTING

Regional public hospitals, Hong Kong.

PATIENTS

Patients attending out-patient pain management clinics between 1 July 2002 and 28 February 2003 were approached to complete a set of standardised questionnaires.

MAIN OUTCOME MEASURES

Demographic profiles, treatment modality, litigation, compensation, social welfare status, Hospital Anxiety Depression Scale, and Medical Outcomes Survey short-form health survey (SF36).

RESULTS

Data from 166 patients were analysed. The median numeric pain rating score was 6 (interquartile range, 2-10). Work-related injury occurred in 34.3% of patients, while another 34% were involved in pain-related litigation and 32% were receiving disability or unemployment benefit. Sixty-four percent of patients were managed by three or more disciplines, while 54.8% were also receiving complimentary alternative medical treatment, mainly traditional Chinese medicine (49.7%). The Hospital Anxiety Depression Score indicated clinical anxiety or depression in 71.1% of patients. All SF36 subscale scores were lower than the local population norm. Unemployed patients had higher depression scores (P = 0.005), while students or retirees had lower physical functioning scores (P = 0.004). Patients who were single had higher role emotion scores than those who were married or separated/widowed (P = 0.011). Logistic regression analysis showed that younger age (odds ratio = 0.95), being married (6.62), work-related injury (15.63) or higher general scores (1.03) were more likely to be associated with litigation. Social welfare benefit was associated with unemployment (3.39) and a lower level of physical functioning (0.98).

CONCLUSION

There was a high prevalence of clinical anxiety, depression, and severe impairment in the health-related quality of life in Hong Kong Chinese patients with chronic non-cancer pain. Specific factors affected the health-related quality of life, likelihood of litigation, and social benefit.

Transplanted human fetal neural stem cells survive, migrate, and differentiate in ischemic rat cerebral cortex

We characterize the survival, migration, and differentiation of human neurospheres derived from CNS stem cells transplanted into the ischemic cortex of rats 7 days after distal middle cerebral artery occlusion. Transplanted neurospheres survived robustly in naive and ischemic brains 4 wk posttransplant. Survival was influenced by proximity of the graft to the stroke lesion and was negatively correlated with the number of IB4-positive inflammatory cells. Targeted migration of the human cells was seen in ischemic animals, with many human cells migrating long distances ( approximately 1.2 mm) predominantly toward the lesion; in naive rats, cells migrated radially from the injection site in smaller number and over shorter distances (0.2 mm). The majority of migrating cells in ischemic rats had a neuronal phenotype. Migrating cells between the graft and the lesion expressed the neuroblast marker doublecortin, whereas human cells at the lesion border expressed the immature neuronal marker beta-tubulin, although a small percentage of cells at the lesion border also expressed glial fibrillary acid protein (GFAP). Thus, transplanted human CNS (hCNS)-derived neurospheres survived robustly in naive and ischemic brains, and the microenvironment influenced their migration and fate.

A multicentre study of the usefulness of liver biopsy in hepatitis C

The role of liver biopsy in the assessment of chronic hepatitis C is generally accepted yet there is no prospective data available to quantify its contribution. A previous single centre pilot study suggested that the clinician could predict the amount of fibrosis and to a lesser extent, inflammation with moderate accuracy. The 2002 National Institute of Health Hepatitis C Consensus Conference recommended further study of the role of liver biopsy. Our objective was to compare a prediction of biopsy findings by expert clinicians using usually available clinical and laboratory data to actual biopsy results in order to determine whether biopsy is required routinely. This was a prospective observational study conducted at seven university centres in which the accuracy of clinician's predictions of the degree of inflammation and fibrosis were compared with the actual liver biopsy using an adaptation of a standard histological scoring system. We studied 81 adults with previously untreated chronic hepatitis C, raised serum transaminases and positive HCV-RNA in serum. Clinicians predicted the inflammatory grade in 44 of 80 cases (55%) and the fibrosis stage in 46 of 81 cases (57%). Nine of 17 cirrhotic cases were predicted (sensitivity 53%, specificity 56%). No unexpected additional diagnoses were made on the biopsies. Thus despite knowledge of the clinical and laboratory investigations of patients with hepatitis C, clinicians are unable to accurately predict the hepatic inflammatory grade and fibrotic stage. Liver biopsy is an essential investigation to accurately evaluate the grade and stage of liver disease patients with hepatitis C.

Out-patient chronic pain service in Hong Kong: prospective study

OBJECTIVE

To examine the profile and referral pattern of patients attending an out-patient pain management service in Hong Kong.

DESIGN

Prospective cross-sectional survey.

SETTING

Regional public hospitals, Hong Kong.

PATIENTS

All patients attending out-patient pain management clinics in the New Territories East public hospitals between 1 September and 31 December 2002.

MAIN OUTCOME MEASURES

Demographic profiles, referring specialty, pain diagnosis, pain sites, duration and severity of pain, treatment modality, litigation, compensation, and social welfare status. Data were collected using a standardised questionnaire.

RESULTS

Two hundred and forty-eight patients were interviewed. Most patients (70%) were middle-aged, with 21% over 60 years. Seventy-nine percent of patients were referred to the clinics either from orthopaedic surgeons (64.1%), general and other surgeons (14.9%), or general practitioners (3.6%). The median (range) duration of pain was 2.3 (0.08-26.7) years. The most common pain diagnoses were musculoskeletal back pain (46.4%) and neuropathic pain (27.8%). A total of 11.3% of the patients had two pain diagnoses, while 40.7% complained of pain in more than one location. Pain in the limbs was the most frequent complaint followed by the head, neck, and back. Approximately 38% of patients had tried four or more treatment modalities. Oral medication was the most common method (86.7%) of pain-relief treatment. More than half of the patients had also tried physiotherapy and traditional Chinese medicine. Approximately 37% of the patients were unemployed, while 31% were receiving social security subsidy. Eighty-six patients had pain associated with a work-related injury, and of these patients, 80% were involved in compensation claims.

CONCLUSIONS

The profile of patients referred to the pain management clinics was complex. Patients were mainly referred from specialists. The economic implication in this group of patients is likely to be significant as many patients utilised multiple treatment modalities, were unemployed and on social welfare benefits, and were involved in compensation and litigation proceedings.

CNS angiitis in graft vs host disease

Graft-vs-host disease (GVHD) is a potentially treatable cause of progressive neurologic decline after bone marrow transplantation (BMT). The authors present histologic confirmation of CNS granulomatous angiitis in a child with chronic GVHD after BMT. Since cranial MRI showed only nonspecific findings, CNS vasculitis associated with GVHD after BMT may be underdiagnosed.

Complement activation in factor D-deficient mice

To assess the contribution of the alternative pathway in complement activation and host defense and its possible role in the regulation of systemic energy balance in vivo, factor D-deficient mice were generated by gene targeting. The mutant mice have no apparent abnormality in development and their body weights are similar to those of factor D-sufficient littermates. Complement activation could not be initiated in the serum of deficient mice by the alternative pathway activators rabbit erythrocytes and zymosan. Surprisingly, injection of cobra venom factor (CVF) caused a profound and reproducible reduction in serum C3 levels, whereas, as expected, there was no C3 reduction in factor B-deficient mice treated similarly. Studies of C3 and factor B activation in vitro by CVF demonstrated that in factor D-deficient serum the alpha chain of C3 was cleaved gradually over a period of 60 min without detectable cleavage of factor B. CVF-dependent C3 cleavage in the deficient serum required the presence of Mg(2+), whereas in normal mouse serum the presence of divalent cations was not required. These results suggest that in mouse proteolytic cleavage of factor B by factor D is not an absolute requirement for the zymogen to active enzyme conformational transition of CVF-bound factor B. Kinetics of opsonization of Streptococcus pneumoniae by C3 fragments was much slower in factor D-deficient serum, suggesting a significant contribution of the alternative pathway to antibacterial host defense early after infection.

Patient-controlled pethidine after major upper abdominal surgery: comparison of the epidural and intravenous routes

We compared epidural (n = 17) and intravenous (n = 20) patient-controlled analgesia (PCA) using pethidine (bolus 10 mg, lockout interval 10 min, 4-h maximum dose 3 mg.kg(-1)) after total gastrectomy. We found that mean (SD) pethidine consumption in the first 24 h was 33% less in the epidural group [255 (85) mg] than in the intravenous group [379 (129) mg, p = 0.002], although most of this difference occurred in the first 8 h. Plasma concentrations of pethidine were lower at 8 h (p < 0.01) in the epidural group, but were similar at 24 h. Pain scores, side-effects, patient satisfaction and patient outcome were similar between groups. Epidural and intravenous pethidine PCA provided similar efficacy after major abdominal surgery, although the epidural route can reduce the amount of pethidine used initially.

[Mutagenic activity of organic pollutants extracted from waters in Guanting Reservoir and Yongding River]

Water samples collected from Guanting Reservoir and Yongding River in July 1999 were examined by Ames test to evaluate the mutagenic activity of organic pollutants. The samples have been concentrated by using XAD-2 resin filled columns. In the test with strain TA98, direct mutagenic effects (-S9) were observed in water extracted from Bridge No.8 and Yanchi at the dosage of 0.8 L/plate, indicating the existence of direct frame shift mutagens. The mutagenic effects disappeared after addition of S9, indicating no pro-mutagen in the samples. In the test with strain TA100, direct base pair substitute mutagenic effect was observed only in the sample from Bridge No. 8 at the dosage of 0.4 L/plate. When adding S9, suspicious positive reaction could exist at the dosage of 0.8 L/plate. The results demonstrated that the water in Yongding River has been heavily polluted by mutagens, for which further studies should be carried out to identify the sources and types of these mutagens.

[Quantitative analysis of human herpes virus type 8 and expression of its genes in patients with multiple myeloma]

OBJECTIVE

To investigate if infection of human herpesvirus type 8 (HHV8) exists in Chinese patients with multiple myeloma (MM), and to identify the relationship between clinical manifestation and the viral load in bone marrow biopsy samples.

METHODS

Real-time quantitative PCR was conducted to define the viral load of HHV8 in bone marrow biopsy samples from 23 patients with MM. Nested PCR was conducted to amplify the KS330(233)Bam fragment of HHV8 from peripheral blood mononuclear cells, bone marrow aspirates and bone marrow biopsy samples. RT-PCR was used to study the expression of suspected oncogenes: vIL-6 and vIRF-1 genes. Bone marrow biopsy samples of 5 patients with blood diseases other than MM and 5 patients with non-blood system diseases were used as controls. PCR product of BCBL-1 cell line was used as positive control.

RESULTS

(1) The positive rate of HHV8 in bone marrow biopsy samples from patients with MM was 69.6% (16/23) by real-time fluorescence quantitative PCR, and 82.6% (19/23) by nested-PCR. 16 bone marrow samples positive by fluorescence quantitative were positive too by nested-PCR. However, 3 bone marrow samples positive by nested-PCR were negative by fluorescence quantative. HHV8 was positive in only one of the 25 bone marrow aspirates from patients with MM (4%) and in none of the 20 peripharal blood samples from patients with MM. PCR showed negative result in 7 bone marrow aspirates taken form 13 MM patients with positive result by fluorescence quantative PCR. HHV8 was negative in bone marrow biopsy samples from patients with other diseases. HHV8 was negative in the peripheral blood samples from 16 MM patients, among which 9 out of the 11 cases with bone marrow biopsy samples taken showed HHV8 positive by fluorescence quatative PCR. Bone marrow biopsy samples of all patients with other blood diseases and non-blood system diseases were HHV8 negative. RT-PCR showed that among 12 MM patients the expression rate of vIRF-1 was 83.3% (10/12), and expression rate of vIL-6 was 0. The PCR positive products tallied with the sequence of HHV8 DNA. Clinical analysis showed that all of the patients with negative results had had chemotherapy.

CONCLUSION

There is a certain association between multiple myeloma pathogenesis and HHV8. In detection of HHVb, nested-PCR is more sensitive than fluorescence quantitaative PCR. The viral gene vILR-1 plays a certain role in the pathogenesis of MM.

Inhibition of progression of heart failure and expression of TGF-beta 1 mRNA in rats with heart failure by the ACE inhibitor quinapril

The cardioprotective effects of quinapril, an angiotensin-converting enzyme inhibitor, were studied in a rat model of heart failure. Twenty-six rats were divided into two groups: one given 20 mg/kg/day quinapril (n = 11), and controls given 0.5% methylcellulose (n = 15). After oral administration for 1 month, quinapril reduced heart weight (from 1.28+/-0.05 to 0.87+/-0.02 g; p < 0.05) without changing body weight. Quinapril lowered left ventricular end-diastolic pressure (from 14.1+/-2.0 to 6.6+/-1.5 mmHg; p < 0.05) and central venous pressure (from 2.7+/-0.9 to 0.7+/-0.4 mmHg), and increased +/- dP/dt (from +2409+/-50 to +3569+/-169 mmHg/s, and from -2318+/-235 to -3960+/-203 mmHg/s; both p < 0.01). The area of myocardial fibrosis was markedly reduced by quinapril (6+/-3%) as compared with controls (29+/-6%; p < 0.01). Expression of transforming growth factor (TGF)-beta1 mRNA was markedly increased in controls as compared with age-matched normal rats. The increase in level of TGF-beta1 mRNA was significantly suppressed by quinapril (from 17.1+/-6.2 to 9.00+/-2.40; p < 0.05). These observations indicated that quinapril has cardioprotective effects on heart failure, and that the beneficial effects may be partly explained by attenuation of fibrotic response through suppression of TGF-beta1 mRNA expression.

Bisoprolol improves survival in rats with heart failure

The cardioprotective effects of bisoprolol were studied in a rat model of severe heart failure induced by autoimmune myocarditis. Twenty-eight days after immunization, Lewis rats were divided into four groups: 0.1 mg/kg/day bisoprolol (Group 0.1), 1.0 mg/kg/day bisoprolol (Group 1) and 10 mg/kg/day bisoprolol (Group 10), and vehicle (0.5% methylcellulose; Group V) (all groups, n = 13). After oral administration for 1 month, heart weight, mean blood pressure, heart rate, central venous pressure, peak left ventricular pressure, left ventricular end-diastolic pressure, +/- dP/dt, and area of fibrosis were measured. Although bisoprolol reduced heart rate (399+/-11/min in Group V, 382+/-10/min in Group 0.1, 348+/-8/min in Group 1 and 302+/-9/min in Group 10) and increased survival (62% in Group V, 69% in Group 0.1, and 100% in Group 1 and Group 10) in a dose-dependent manner, this drug did not change heart weight, the area of myocardial fibrosis or hemodynamic parameters. These observations suggested that bisoprolol may improve survival independently of its effect on left ventricular function by reducing sudden death in patients with severe heart failure.

Transgenic mice with overexpression of human scavenger receptor A on endothelial cells

OBJECTIVES

To establish a new transgenic mouse model for determining the function and role of human scavenger receptor A (SR-A) in atherosclerosis in vivo.

METHODS

Human scavenger receptor minigene-driven mouse tie-1 promoter was constructed and confirmed by endonuclease digestion and sequence analysis. Transgenic mice were generated via the microinjection method. PCR and Southern blot were used to screen the positive transgenic mice. RT-PCR and immunohistochemical analysis were used to detect the level and location of human SR-AI expression in transgenic mice. The activity of human SR-AI was determined by morphologic observation of aortic endothelial cells of transgenic mice under transmission electron microscopy.

RESULTS

The electrophoresis assay showed the expected 4 fragments of 0.9 kb, 1.1 kb, 1.2 kb and 4.2 kb in the Sma I digest and 2 fragments of 0.8 kb and 6.7 kb in Bgl II digest of plasmids pTie-1/hSR-A. The fragment sequence of tie-1 promoter and human SR-A cDNA in plasmids pTie-1/hSR-A was correct and no ATG before the translation initiation sites of human SR-A was found by sequence analysis. 561 injected and surviving embryos with the purified human SR-A minigene were implanted into the oviducts of 19 ICR pseudopregnant mice. Among the 54 surviving pups from 13 foster mothers, 7 were identified by PCR and Southern blot analysis. The results of RT-PCR and immunohistochemical analysis showed human SR-A was specifically expressed on vascular endothelial cells of the aorta and renal artery, as well as hepatic sinusoidal endothelial cells in transgenic mice. Transmission electron microscope (TEM) of aorta of transgenic mice showed that a large number of vesicles, multivesicle bodies and swollen mitochondria filled the plasma of endothelial cells.

CONCLUSIONS

A transgenic mouse model with overexpression of human SR-A in endothelial cells was successfully established. The transgene was integrated and transmitted into the chromosome of transgenic mice. Tie-1 promoter controlled the transgene to express in endothelial cells in mice. Pinocytic activity of aortic endothelial cells in transgenic mice was higher than that of C57BL/6J mice. Our studies will provide a new transgenic model for investigation of atherosclerosis and functions of human SR-A.

Administration of adenoviral vectors induces gangrene in acutely ischemic rat hindlimbs: role of capsid protein-induced inflammation

PURPOSE

The initial purpose of this study was to determine the effects of intravascular adenoviral vector-mediated gene transfer of endothelial nitric oxide synthase (AdeNOS) on experimental hindlimb ischemia in the rat. Unexpectedly, administration of AdeNOS immediately after induction of acute limb ischemia led to limb gangrene. We subsequently sought to define the molecular mechanisms responsible for this unusual effect and to devise adenoviral gene transfer strategies to prevent the development of gangrene in acutely ischemic limbs.

METHODS

Phosphate-buffered saline or adenoviral vectors containing the bovine endothelial nitric oxide synthase gene (AdeNOS) or no transgene (Ad-E1) were injected intra-arterially into the hindlimb of a rat under vascular isolation immediately after surgical induction of severe ischemia. Hematoxylin and eosin staining was performed on muscle sections to evaluate inflammation. A separate group of animals was injected with an adenovirus containing a nontranscribable genome, treated with cyclosporine, or received delayed administration of the adenoviral vector. Gene expression after delayed adenoviral gene transfer was assessed with immunohistochemistry, Western blotting, and nitric oxide synthase (NOS) activity assay.

RESULTS

Both AdeNOS and Ad-E1 caused gangrene of the entire hindlimb within 12 days in a dose-dependent manner, at a threshold concentration of 1 x 10(9) plaque-forming unit/mL. Adenoviral delivery was associated with more inflammation and edema compared with phosphate-buffered saline histologically. Inactivation of adenoviral DNA transcription did not affect induction of gangrene. However, gangrene was prevented by concurrent immunosuppression with cyclosporine or delayed administration of the vector. Delayed administration allowed adenoviral gene expression as determined by immunohistochemistry, NOS protein levels, and an assay of NOS enzyme activity.

CONCLUSION

Intra-arterial administration of adenoviral vectors, under vascular isolation, immediately after induction of acute ischemia causes inflammation and subsequent limb gangrene. The inflammatory response is unrelated to the expression of the recombinant transgene or the adenoviral genome and is likely due to the adenoviral capsid proteins. However, administration of cyclosporine or delayed injection of the adenoviral vector is a method that can be used for adenoviral mediated gene transfer in limb ischemia.

Frequent demonstration of human herpesvirus 8 (HHV-8) in bone marrow biopsy samples from Turkish patients with multiple myeloma (MM)

In order to investigate the frequency of HHV-8 in MM patients from another geographic location, we obtained fresh bone marrow (BM) biopsies from Turkish patients with MM (n = 21), monoclonal gammopathy of undetermined significance (MGUS) (n = 2), plasmacytoma (n = 1) with BM plasma cell infiltration, various hematological disorders (n = 6), and five healthy Turkish controls. The frequency of HHV-8 was analyzed by polymerase chain reaction (PCR) in two independent laboratories in the USA and in Turkey. Using fresh BM biopsies, 17/21 MM patients were positive for HHV-8 whereas all five healthy controls, and six patients with other hematological disorders were negative. Two patients with MGUS, and one patient with a solitary plasmacytoma were also negative. The data from the two laboratories were completely concordant. Also using primer pairs for v IRF and v IL-8R confirmed the results observed with the KS330233 primers. Furthermore, sequence analysis demonstrated a C3 strain pattern in the ORF26 region which was also found in MM patients from the US. Thus, HHV-8 is present in the majority of Turkish MM patients, and the absence of the virus in healthy controls further supports its role in the pathogenesis of MM.

Behavioral and histological outcomes following graded spinal cord contusion injury in the C57Bl/6 mouse

A computer-controlled electromagnetic spinal cord injury device (ESCID) has been adapted to develop a mouse model of spinal cord contusion injury. In the present study, we have extended this model in C57Bl/6 mice with behavioral and histopathological outcome assessment. Three groups of mice received a laminectomy at the T(9) vertebral level followed by a contusion injury from a predetermined starting load of 1500 dynes. Contusion was produced by rapid displacement of the spinal cord to a peak distance of 0.3, 0.5, or 0.8 mm, with the entire injury and retraction procedure completed over a 23-ms epoch. Control groups received laminectomy alone or complete transection. Functional recovery was examined for 9 weeks after injury using the BBB locomotor rating scale, grid walking, and footprint analysis. Distinct patterns of locomotor recovery were evident across the five groups. Measurements of spared white matter at the epicenter, lesion length, and cross-sectional area of fibronectin-immunopositive scar tissue were also significantly different between injury groups. The severity of injury corresponded with the biomechanical measures recorded at the time of impact as well as with behavioral and histological parameters. The results demonstrate that graded contusion injuries can be produced reliably in mice using the ESCID. The data provide a thorough and quantitative analysis of the effects of contusion injury on long-term behavioral and histological outcome measures in this strain and species.

Theory for phase transitions in insulating V2O3

We show that the recently proposed S = 2 bond model with orbital degrees of freedom for insulating V2O3 not only explains the anomalous magnetic ordering but also other mysteries of the magnetic phase transition. The model contains an additional orbital degree of freedom that exhibits a zero temperature quantum phase transition in the Ising universality class.

[Cloning and sequence analysis of the phytase phyA gene of Aspergillus niger N25]

The phyA encoding phytase of Aspergillus niger N25 was amplified by the polymerase chain reaction (PCR) with primers designed according to the sequences of the phyA in GenBank. The amplified fragment was cloned and sequenced. The results show that: the coding region is 1506 bp in size, includes a 102 bp intron, and encodes a peptide of 476 amino acid residues, in which there is a signal peptide with 19 amino acids and a mature peptide of 448 amino acids. Comparison of this sequence with the phyA of the natural A. niger NRRL3135 (GenBank Accession: M94550), the most highly secreting-phytase strain, shows that the nucleotide homology is as high as 96.746%, and the amino acid homology comes up to 97.64%. The phyA of A. niger N25 strain in this paper is appropriate to be used to construct the phytase gene-engineering bacteria.

Monitoring priority pollutants in a sewage treatment process by dichloromethane extraction and triolein-semipermeable membrane device (SPMD)

Semipermeable membrane devices containing a neutral lipid triolein (triolein-SPMD) and conventional dichloromethane extraction were used to monitor the presence and concentrations of priority organic pollutants in a sewage treatment process in Beijing, China. Both samples gave similar information on the presence of target PCB congeners, PAHs, Organochlorine pesticides and substituted benzenes in sewage at all sites. After 20 days' sampling, the concentrations of contaminants in triolein of SPMD were much higher than those in dichloromethane extracts, which resulted in easier analysis, improved the detection limits, and increased the accuracy. Previous field mean sampling rates for SPMD were used to estimate concentrations of PCB congeners in sewage, which compared to their determined concentrations by dichloromethane extraction. The consistency and superiority of SPMD technology were proved for the detection of priority organic contaminants from sewage. Lower removal rates for PCB congeners and PAHs coincided with the persistence of them in environment. More attention should be paid to urban sewage treatment process adopting activated-sludge method, where priority organic pollutants might not be removed, even present higher concentrations after treatment.

Carvedilol enhances atrial and brain natriuretic peptide mRNA expression and release in rat heart

To clarify the role of the natriuretic peptide (NP) system in the myocardial protective effects of carvedilol, a beta-blocking agent, we investigated the effects of carvedilol on the NP system in the rat heart. After oral administration of carvedilol (low-dose group: 2 mg/kg/day, group C2; high-dose group: 20 mg/kg/day, group C20) for 1 week, plasma rat atrial NP (r-ANP), atrial mRNA levels of ANP, left ventricular mRNA of brain NP (BNP), NP receptor-A and NP receptor-C (NPR-C) (as a clearance receptor) were measured. Values were compared with those in vehicle-treatment rats (group V). The concentration of r-ANP was significantly higher in group C2 (135 +/- 9 pg/ml) and group C20 (161 +/- 11 pg/ml) than group V (75 +/- 6 pg/ml; both p < 0.01). ANP and BNP mRNA levels were significantly increased and NPR-C was significantly down regulated in group C2 (151 +/- 7, 120 +/- 8 and 78 +/- 7%, respectively, vs. group V) and group C20 (164 +/- 8. 133 +/- 7 and 72 +/- 8%, respectively, vs. group V) compared with group V (all p < 0.01). These results suggest that not only a high dose, but a low dose of carvedilol has the effect of increasing plasma ANP and BNP levels. This effect was closely related to the upregulation of ANP and BNP mRNA expression, and the down regulation of NPR-C mRNA expression in the heart. These mechanisms seem to account for a sizable portion of the protective effect of carvedilol for heart diseases.

[Large-capacity expanded cytoline-induced killer cells and its cytotoxic activity]

This study was conducted to establish the large-capacity culture methd of cytokine-induced killer (CIK) cells for clinical therapy and assess its effect on the fuction of cell-mediated immunity following autologous CIK cells reinfusion. Autologus CIK cells were expanded in 1000 ml culture-bag and reinfused back. The MTT method was used to test the cytotoxic activity of CIK cells before and after reinfusion. The results showed that the total amount of autologous CIK cells reinfusion exceeded 1.6 x 10(10) with the use of the culture method of large-capacity. The PBMNC from patients treated by CIK cells showed significant increase in cytotoxic activity, no side effects were observed, and therefore the large-capacity culture method of CIK cells is a simle and safe therapy for treating the minimum residue of diseases.

[Construction of B. thuringiensis shuttle vector and expression of the cry1C gene]

We have constructed the E. coli-Bt shuttle vector pHV-1 by cloning the replicon (approximately 1.6 kb) of Bt ken-Ag and the aphI gene of pUC4K into pUC19. The rate of plasmid maintenance is more than 80% after 100 generations in E. coli, whereas 80% after 40 generations in Bti 4Q8. We have also constructed pHV-cry1C through cloning the alpha-amylase promoter from B. licheniformis and the cry1C gene from Bt 9510 into pHV-1 and introduced it into Bti 4Q8 by means of electroporation. Under the microscope, we can see that there is no crystal in Bti 4Q8, however, there are many rhomboid crystals in Bti 4Q8 (pHV-cry1C), which are smaller than those of Bt 9510. The bioassay result of Bti 4Q8 (pHV-cry1C) demonstrates that the expressed crystal protein is insecticidally active against Spodoptera exigue.

DDT, PAH and PCB in sediments from the intertidal zone of the Bohai Sea and the Yellow Sea

Current contents of persistent organic contaminants, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and the congeners (naphthalene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo(a)anthracene, benzo(a)pyrene and benzo(e)pyrene), DDTs and metabolites in the intertidal sediments of the Bohai Sea and the Yellow Sea were studied. The mean levels of DDTs, PAHs and PCBs were 177.52, 877.2 and 3.4 ng g-1 dry weight, respectively. The spatial trends of the contaminant residue levels were analysed too.

A prospective survey of patients after cessation of patient-controlled analgesia

Cessation of IV patient-controlled analgesia (PCA) in the postoperative period is often an arbitrary clinical decision. We conducted a prospective survey of patients 24 h after cessation of IV PCA morphine to determine whether they wished to be restarted on PCA, and to evaluate factors affecting this decision. One hundred and fifteen patients were surveyed over a 3-mo period. Thirty-eight patients (33%) wished to restart PCA. The most common reason was the expectation that IV PCA would be more effective. Age, sex, type of surgery, duration of PCA use, side effects, pain scores, and reasons for cessation of PCA did not affect the decision. The reasons given by those who did not wish to restart PCA were minimal pain (51.9%), inconvenient PCA machine (15.6%), ineffective analgesia by IV PCA (11.7%), side effects during PCA (11.7%), and wishing to tolerate pain (7.8%). PCA morphine consumption in the 24-h period before cessation of PCA (mean [SD]) was larger in patients wishing to restart PCA than in those who did not (21.1 [14.8] mg vs 15.1 [15.1] mg; P < 0.05). In conclusion, the clinical decisions to cease IV PCA do not predict patient acceptance of and satisfaction with the decision and with subsequent pain treatment. Morphine consumption may predict a patient's acceptance of ceasing PCA.

IMPLICATIONS

We surveyed patients 24 h after cessation of IV patient-controlled analgesia (PCA). This survey revealed that the usual clinical reasons to stop IV PCA might not be the most appropriate. Patients have different reasons why they wish to restart or not restart IV PCA. The cessation of PCA should be individualized.

[Anti-inflammatory effect of saucernetilignan-8]

Saucernetilignan-8 (Sc-8), which was isolated from Saururus chinesis, has significant anti-inflammatory effect.

Cardiovascular responsivity to stress in adolescents with and without persistently elevated blood pressure

OBJECTIVES

The goal of this study was to compare the cardiovascular responses to behavioural stressors of three groups of adolescents who differed in blood pressure status across assessments.

DESIGN

Casual blood pressure of adolescents who were identified as having elevated blood pressure during a school screen was re-evaluated in the laboratory. The adolescents were classified into two groups: (i) those with consistently elevated blood pressure across school and laboratory assessments and (i) those with labile blood pressure whose blood pressure in the laboratory was below 130/80 mmHg. A comparison group of adolescents with consistently normal blood pressure was also included.

METHODS

Cardiovascular parameters were assessed during rest and during two behavioural stressors, the evaluated speaking task and the mirror tracing task.

RESULTS

Adolescents with elevated blood pressure were more vascularly responsive across stressors than adolescents with labile blood pressure, who, in turn, were more reactive than adolescents with normal blood pressure.

CONCLUSIONS

These results suggest that vascular reactivity to behavioural stressors may be useful in predicting risk of hypertension because of its sensitivity in distinguishing adolescents with consistently elevated blood pressure from those with labile blood pressure and those with normal blood pressure.

Functional mosaic organization of mouse olfactory receptor neurons

In contrast to rapid progress in the molecular biology of olfaction, there are few physiological data to characterize the odor response properties of different populations of olfactory receptor neurons (ORNs) and their spatial distributions across the epithelium, which is essential for understanding the coding mechanisms underlying odor discrimination and recognition. We have tested the hypothesis that the ORNs are arranged in a functional mosaic, using an intact epithelial preparation from the mouse, in which odor responses of many ORNs in situ can be monitored simultaneously with calcium imaging techniques. ORNs responding to a given odor were widely distributed across epithelium and intermingled with ORNs responding to other odors. Tight clusters of ORNs responding to the same odor were observed. For a given odor, more ORNs were recruited when the concentration was increased. ORNs were able to distinguish between pairs of enantiomers by showing distinct but somewhat overlapping patterns. The results provide evidence regarding the response spectra of ORNs in situ, supporting the combinatorial coding of odor quality and intensity by different ORN subsets.

Speciation of key arsenic metabolic intermediates in human urine

Biomethylation is the major human metabolic pathway for inorganic arsenic, and the speciation of arsenic metabolites is essential to a better understanding of arsenic metabolism and health effects. Here we describe a technique for the speciation of arsenic in human urine and demonstrate its application to the discovery of key arsenic metabolic intermediates, monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), in human urine. The study provides a direct evidence in support of the proposed arsenic methylation pathway in the human. The finding of MMAIII and DMAIII in human urine, along with recent studies showing the high toxicity of these arsenicals, suggests that the usual belief of arsenic detoxification by methylation needs to be reconsidered. The arsenic speciation technique is based on ion pair chromatographic separation of arsenic species on a 3-micron particle size column at 50 degrees C followed by hydride generation atomic fluorescence detection. Speciation of MMAIII, DMAIII, arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV) in urine samples is complete in 6 min with detection limits of 0.5-2 micrograms/L. There is no need for any sample pretreatment. The capability of rapid analysis of trace levels of arsenic species, which resulted in the findings of the key metabolic intermediates, makes the technique useful for routine arsenic speciation analysis required for toxicological and epidemiological studies.

Determination of monomethylarsonous acid, a key arsenic methylation intermediate, in human urine

In this study we report on the finding of monomethylarsonous acid [MMA(III)] in human urine. This newly identified arsenic species is a key intermediate in the metabolic pathway of arsenic biomethylation, which involves stepwise reduction of pentavalent to trivalent arsenic species followed by oxidative addition of a methyl group. Arsenic speciation was carried out using ion-pair chromatographic separation of arsenic compounds with hydride generation atomic fluorescence spectrometry detection. Speciation of the inorganic arsenite [As(III)], inorganic arsenate [As(V)], monomethylarsonic acid [MMA(V)], dimethylarsinic acid [DMA(V)], and MMA(III) in a urine sample was complete in 5 min. Urine samples collected from humans before and after a single oral administration of 300 mg sodium 2,3-dimercapto-1-propane sulfonate (DMPS) were analyzed for arsenic species. MMA(III) was found in 51 out of 123 urine samples collected from 41 people in inner Mongolia 0-6 hr after the administration of DMPS. MMA(III )in urine samples did not arise from the reduction of MMA(V) by DMPS. DMPS probably assisted the release of MMA(III) that was formed in the body. Along with the presence of MMA(III), there was an increase in the relative concentration of MMA(V) and a decrease in DMA(V) in the urine samples collected after the DMPS ingestion.

[An ultrastructural observation on rat retina after photoreceptor cell implantation]

OBJECTIVE

To further study the retinal neuronal signal.

METHODS

The Wistar/RCS (RCS rats are rats with hereditary photoreceptor degeneration) rats were respectively as donors/acceptors, and the retinal pathway was reconstructed with the technique of pure photoreceptor transplantation. The photoreceptor layer of the retina was obtained with the technique of retinal whittle by manual method or excimer laser. The specimens were got separately at 2 weeks and 1 month after the transplantation and studied under the light and transmission electron microscopes.

RESULTS

Most transplanted photoreceptors with physical poles were lined up regularly between the retinal pigment epithelium (RPE) and inner nuclear layer. It was shown that in the new outer plexiform layer the relatively integral synapse and its interconnection were seen.

CONCLUSION

The retinal neuronal pathway can be reconstructed by retinal transplantation.

[Analysis of lymphocytic clone formation after stem cell transplantation and immunological reconstitution by gene fingerprinting]

OBJECTIVE

To analyze T lymphocytic clone formation in patients with malignant disease after bone marrow or peripheral blood stem cell transplantation and to understand the relationship between immunological reconstitution and clinic remission.

METHODS

Due to the different TCRgamma gene rearrangements in different gamma/delta T cell clones, a gene fingerprinting was set up by PCR and denatured gel electrophoresis. The gene fingerprinting was used to analyze the gamma-delta T cell clone variations in 8 patients who received stem transplantation. In order to identify the source of the regenerated lymphocytes, the polymorphism of microsatellite was used at mean time.

RESULTS

After PCR amplification and electrophoresis of each TCRgammaV region gene on a 60 cm sequence gel, a gene fingerprinting composed of about a hundred bands was set up. It showed the basic distribution of the dominant gamma/delta T cell clones in the body. Usually, a new band presenting after transplantation represented an expansive lymphocytic clone. Successful immunological reconstitution led to a good prognosis; and unsuccessful immunological reconstitution led to bad prognosis. After transplantation, some T cell clones expanded. Comparing the sequences of a expansive T cell clone in a multiple myeloma patient after auto-stem cell transplantation with 230 000 genes of immunoglobulin and T cell receptor in GeneBank, we found that two T cell line had homogenous sequences. Both T cell clones recognized homogeneous antigen.

CONCLUSION

A new method to observe the distribution of gamma/delta T cells called gene fingerprinting was set up. Gene fingerprinting is useful in the analysis of immunological reconstitution after stem cells transplantation. The effect of transplantation is correlated to immunological reconstitution. Transplantation patients may appear some expansive T cell clones; probably they have anti - tumor effect.

Orbitally degenerate spin-1 model for insulating V2O3

Motivated by recent neutron, x-ray absorption, and resonant scattering experiments, we revisit the electronic structure of V2O3. We propose a model in which S = 1 V3+ ions are coupled in the vertical V-V pairs forming twofold orbitally degenerate configurations with S = 2. Ferro-orbital ordering of the V-V pairs gives a description which is consistent with all experiments in the antiferromagnetic insulating phase.

Occurrence of monomethylarsonous acid in urine of humans exposed to inorganic arsenic

Monomethylarsonous acid (MMA(III)) has been detected for the first time in the urine of some humans exposed to inorganic arsenic in their drinking water. Our experiments have dealt with subjects in Romania who have been exposed to 2.8, 29, 84, or 161 microg of As/L in their drinking water. In the latter two groups, MMA(III) was 11 and 7% of the urinary arsenic while the monomethylarsonic acid (MMA(V)) was 14 and 13%, respectively. Of our 58 subjects, 17% had MMA(III) in their urine. MMA(III) was not found in urine of any members of the group with the lowest level of As exposure. If the lowest-level As exposure group is excluded, 23% of our subjects had MMA(III) in their urine. Our results indicate that (a) future studies concerning urinary arsenic profiles of arsenic-exposed humans must determine MMA(III) concentrations, (b) previous studies of urinary profiles dealing with humans exposed to arsenic need to be re-examined and re-evaluated, and (c) since MMA(III) is more toxic than inorganic arsenite, a re-examination is needed of the two hypotheses which hold that methylation is a detoxication process for inorganic arsenite and that inorganic arsenite is the major cause of the toxicity and carcinogenicity of inorganic arsenic.

[Expression of ET of early ischemic myocardium in rats]

To study the expression of ET of early ischemic myocardium, we designed a model of early myocardial ischemia (EMI) in rats. The study was conducted with SABC method and HE staining. Cardiac myocytes of ischemia showed a little ET-positive at 60-min. Cardiac myocytes, endothelium and smooth muscle of vessel showed ET-positive staining in the area of EMI after 120-min. Staining was negative for Ischemia myocardium at 30-min and for the control group. No change was seen with HE staining in all groups. The data indicates that ET-SABC method may reveal the injury of myocardial ischemia 60-min and longer and may provide a new marker to diagnose EMI in forensic pathology.

DMPS-arsenic challenge test. II. Modulation of arsenic species, including monomethylarsonous acid (MMA(III)), excreted in human urine

The administration of sodium 2,3-dimercapto-1-propane sulfonate (DMPS) to humans chronically exposed to inorganic arsenic in their drinking water resulted in the increased urinary excretion of arsenic, the appearance and identification of monomethylarsonous acid (MMA(III)) in their urine, and a large decrease in the concentration and percentage of urinary dimethylarsinic acid (DMA). This is the first time that MMA(III) has been detected in the urine. In vitro biochemical experiments were then designed and performed to understand the urinary appearance of MMA(III) and decrease of DMA. The DMPS-MMA(III) complex was not active as a substrate for the MMA(III) methyltransferase. The experimental results support the hypothesis that DMPS competes with endogenous ligands for MMA(III), forming a DMPS-MMA complex that is readily excreted in the urine and points out the need for studying the biochemical toxicology of MMA(III). It should be emphasized that MMA(III) was excreted in the urine only after DMPS administration. The results of these studies raise many questions about the potential central role of MMA(III) in the toxicity of inorganic arsenic and to the potential involvement of MMA(III) in the little-understood etiology of hyperkeratosis, hyperpigmentation, and cancer that can result from chronic inorganic arsenic exposure.

Effects of Manduca diuresin on neonates of the tobacco hornworm, Manduca sexta

Manduca diuresin (MD), a 30 amino acid peptide, was isolated and identified from the type IIb median neurosecretory cells in the brain of adult Manduca sexta (Blackburn et al., Biochem. Biophys. Res. Commun., 181, 927-932, 1991). The synthetic hormone stimulates water loss in the adult moth both in vitro using isolated Malphigian tubule preparations and in vivo using decapitated adult moths as bioassay animals (Blackburn and Ma, Arch. Insect Biochem. Physiol., 27, 3-10, 1994). In the present study, MD was shown to have adverse physiological effects on neonates of Manduca sexta when fed synthetic hormone-treated leaf discs. With a sustained diet of MD-treated discs, neonates exhibited symptoms of reduced food consumption and marginal weight increases. In addition to slowed growth and reduced developmental rates, a high percentage of these neonates failed to molt into second instar larvae and death usually followed shortly thereafter. This is a first report that a synthetic insect neuropeptide has shown detrimental effect on insect larvae by ingestion. The possibility of utilizing this peptide in plant protection is discussed.

Methodological issues in the use of guidelines and audit to improve clinical effectiveness in breast cancer in one United Kingdom health region

AIMS

To develop a system to improve and monitor clinical performance in the management of breast cancer patients in one United Kingdom health region.

DESIGN

An observational study of the changes brought about by the introduction of new structures to influence clinical practice and monitor change.

SETTING

North Thames (East) Health region, comprising seven purchasing health authorities and 21 acute hospitals treating breast cancer.

SUBJECTS

The multi-disciplinary breast teams in 21 hospitals and an audit sample of 419 (28%) of the breast cancer patients diagnosed in 1992 in the region.

INTERVENTIONS

Evidence-based interventions for changing clinical practice: regional guidelines, senior clinicians acting as <<opinion leaders>>, audit of quality rather than cost of services, ownership of data by clinicians, confidential feed-back to participants and education.

OUTCOME MEASURES

Qualitative measures of organizational and behavioural change. Quantitative measures of clinical outcomes compared to guideline targets and to results from previous studies within this population.

RESULTS

Organizational changes included the involvement, participation of and feedback to 16 specialist surgeons and their multidisciplinary teams in 21 hospitals. Regional clinical guidelines were developed in 6 months and the dataset piloted within 9 months. The audit cycle was completed within 2 years. The pilot study led to prospective audit at the end of 2 years for all breast cancers in the region and a 15-fold increase in high quality clinical information for these patients. Changes in clinical practice between 1990 and 1992 were observed in the use of chemotherapy (up from 17-23%) and axillary surgery (up from 46-76%).

CONCLUSIONS

The approach used facilitated rapid change and found a balance between local involvement (essential for sustainability within a hospital setting) and regional standardization (essential for comparability across hospitals). The principles of the approach are generalized to other cancers and to other parts of the UK and abroad.

Adenoviral-mediated gene transfer of ICP47 inhibits major histocompatibility complex class I expression on vascular cells in vitro

PURPOSE

Many viruses have evolved mechanisms to evade detection by the host immune system. The herpes simplex gene ICP47 encodes a protein that binds to the host antigen-processing transporter, inhibiting the formation of major histocompatibility complex class I (MHC-I) antigens in infected cells. MHC-I antigen expression is also important in acute allograft rejection. This study was designed to quantitate the effect of adenoviral-mediated gene transfer of ICP47 on MHC-I cell surface expression of human vascular cells. We hypothesized that the transduction of vascular cells with a replication-incompetent adenoviral vector that was expressing ICP47 (AdICP47) would inhibit constitutive and inducible MHC-I expression and thereby reduce the rate of cytolysis of ICP47-transduced vascular cells by sensitized cytotoxic T lymphocytes (CTL).

METHODS

A replication-incompetent adenoviral vector, AdICP47, was created to express ICP47 driven by the cytomegalovirus immediate early promoter. Cultured human vascular endothelial and smooth muscle cells and human dermal fibroblasts were transduced with either AdICP47 or the control empty vector AddlE1. Cell surface constitutive and gamma-interferon-induced MHC-I expression were quantitated by flow cytometry. A standard 4-hour chromium release cytotoxicity assay was used to determine the percent cytolysis of transduced and nontransduced endothelial cells by sensitized CTL. Finally, to quantitate the specificity of the effect of ICP47 on MHC-I expression, adhesion molecule expression was quantitated in both transduced and nontransduced cells.

RESULTS

Constitutive MHC-I expression in AdICP47-transduced endothelial cells was inhibited by a mean of 84% +/- 5% (SEM) in five experiments. After 48 hours of exposure to gamma-interferon, AdICP47-transduced cells exhibited a mean of 66% +/- 8% lower MHC-I expression than nontransduced cells. Similar inhibition in MHC-I expression was achieved in AdICP47-transduced vascular smooth muscle cells and dermal fibroblasts. Percent cytolysis of AdICP47-transduced endothelial cells by CTL was reduced by 72%. Finally, the specificity of the effect of transduction of ICP47 on vascular cell MHC-I expression was confirmed by a lack of significant change in either constitutive or tumor necrosis factor-induced vascular cell adhesion molecule/intercellular adhesion molecule expression.

CONCLUSION

Transduction of vascular cells with AdICP47 strongly inhibits both constitutive and inducible MHC-I expression in human vascular cells. AdICP47-transduced cells exhibited a substantial reduction in cytolysis by CTL. Thus AdICP47 transduction holds promise as a technique to characterize the role of MHC-I expression in acute vascular allograft rejection in vivo and as a potential therapeutic intervention.

Intracellular mRNA cleavage induced through activation of RNase P by nuclease-resistant external guide sequences

Most antisense oligonucleotide experiments are performed with molecules containing RNase H-competent backbones. However, RNase H may cleave nontargeted mRNAs bound to only partially complementary oligonucleotides. Decreasing such "irrelevant cleavage" would be of critical importance to the ability of the antisense biotechnology to provide accurate assessment of gene function. RNase P is a ubiquitous endogenous cellular ribozyme whose function is to cleave the 5' terminus of precursor tRNAs to generate the mature tRNA. To recruit RNase P, complementary oligonucleotides called external guide sequences (EGS), which mimic structural features of precursor tRNA, were incorporated into an antisense 2'-O-methyl oligoribonucleotide targeted to the 3' region of the PKC-alpha mRNA. In T24 human bladder carcinoma cells, these EGSs, but not control sequences, were highly effective in downregulating PKC-alpha protein and mRNA expression. Furthermore, the downregulation is dependent on the presence of, and base sequence in, the T-loop. Similar observations were made with an EGS targeted to the bcl-xL mRNA.