Coupling of arterial pulse and 10-Hz rhythm in sympathetic nerve discharge

We used time series analysis to characterize the relationships among the arterial pulse (AP) and the cardiac-related and 10-Hz rhythms in sympathetic nerve discharge (SND) of urethane-anesthetized cats. We found that 10-Hz activity was more tightly coupled to the AP than to the cardiac-related rhythm. These data support the view that the dynamic coupling of AP and the 10-Hz rhythm in SND involves a direct influence of baroreceptor activity on the 10-Hz oscillator.

Frequency of hepatitis B virus reactivation in cancer patients undergoing cytotoxic chemotherapy: a prospective study of 626 patients with identification of risk factors

Hepatitis B virus (HBV) reactivation is a well-described complication in cancer patients who receive cytotoxic chemotherapy and may result in varying degrees of liver damage. As chemotherapy is used increasingly in cancer patients, HBV reactivation during cytotoxic treatment may become a more common problem. In lymphoma patients, the incidence of chronic HBV infection has been reported to be 26%, of whom 47% developed HBV reactivation during chemotherapy. However, corresponding data for patients with other malignancies undergoing cytotoxic chemotherapy are not known. In this prospective study, hepatitis B surface antigen (HBsAg) was determined in 626 consecutive cancer patients who received cytotoxic chemotherapy over a 12-month period. Seventy-eight patients (12%) were found to be HBsAg positive. Thirty-four (44%) developed raised alanine transaminase during their course of chemotherapy. In these 34 patients, hepatitis was attributed to HBV reactivation in 15 patients (44%), chronic active HBV infection in 1 patient (3%), hepatitis C infection in 1 patient (3%), malignant hepatic infiltration in 2 patients (6%), and the use of hepatotoxic chemotherapeutic agents in 11 patients (32%). The causes of hepatitis were unknown in 4 patients (12%). HBV reactivation was more likely to develop in patients who were male, younger age, HBeAg seropositive, and those with lymphoma. Presence of malignant hepatic infiltration, baseline pre-treatment alanine transaminase, total bilirubin, and HBV DNA levels did not correlate with the development of HBV reactivation. Of the 15 patients who developed HBV reactivation, antiviral therapy with lamivudine was available and used in 9. There was no HBV-related mortality during chemotherapy. It is concluded that in patients with chronic HBV infection under chemotherapy, HBV reactivation occurs in nearly 20% of them and accounts for 44% of hepatitis cases. The risk factors identified include male sex, younger age, HBeAg seropositive, and the diagnosis of lymphoma. In HBV endemic areas, patients with risk factors for HBV reactivation should be identified prior to receiving cytotoxic treatment and monitored closely. The potential benefit of lamivudine requires further confirmation.

Sequence variations of precore/core and precore promoter regions of hepatitis B virus in patients with or without viral reactivation during cytotoxic chemotherapy

Reactivation of the hepatitis B virus (HBV) is a well-described complication among cancer patients undergoing cytotoxic chemotherapy. Mutations in the preC/C and the preC promoter regions of HBV have been reported in some patients who developed this condition. A G-to-A mutation at nt 1896 in the preC/C region (HBeAg negative/ anti-HBe positive) has been associated with more severe liver disease than that caused by wild type virus. In addition, it has been suggested that patients with these mutations may be more likely to reactivate than those with the wild type virus. Whether or not such mutations were present before the commencement of or developed during the course of cytotoxic chemotherapy is not known. In this study, 28 cancer patients (consisting of 14 consecutive patients who developed HBV reactivation and another 14 who had no reactivation during cytotoxic chemotherapy) are reported. The objectives were firstly, to determine the prechemotherapy HBeAg status and nucleotide sequences of the preC/C and preC promoter regions of HBV in order to determine if these parameters affected the rate of reactivation, and secondly, for those who developed reactivation, to determine whether the mutations were present before chemotherapy or developed during, possibly as a result of, cytotoxic chemotherapy. HBV DNA was amplified by PCR and nucleotide sequencing performed on samples taken prior to chemotherapy and at the time of reactivation. Results revealed that 16 of the 28 patients were HBeAg negative/anti-HBe positive. Of these 16, four (57%) of the seven patients who had nt 1896 mutation, but only one (17%) of the six who had the wild type HBV genome, developed reactivation. Three had no detectable HBV DNA. In the majority of cases, the type of virus, i.e. wild/mutant at preC/C, that was detected during the reactivation was identical to that detected in the pretreatment samples. With respect to the preC promoter region, the two commonest mutations detected were at nt 1762 (A to T) and nt 1764 (G to A). When this region was translated into amino acid sequences, stop codons leading to truncated X protein at carboxyl terminus were found in four patients, three of whom developed HBV reactivation. We conclude that chronic HBV carriers who are HBeAg negative/anti-HBe positive with nt 1896 mutation (G to A) may be more likely to develop HBV reactivation during cytotoxic chemotherapy than those with the wild type virus. Cytotoxic chemotherapy does not appear to select out mutant HBV, or to be consistently mutagenic in patients who develop HBV reactivation. The occurrence of stop codons in the amino acid sequences of the X protein in three patients who developed HBV reactivation, including one who was detected only at the time of reactivation, is of particular interest, as such mutant viruses remain replication competent.

The function of PML in p53-dependent apoptosis

The PML gene of acute promyelocytic leukaemia (APL) encodes a growth- and tumour-suppresor protein that is essential for several apoptotic signals. The mechanisms by which PML exerts its pro-apoptotic function are still unknown. Here we show that PML acts as a transcriptional co-activator with p53. PML physically interacts with p53 both in vitro and in vivo and co-localizes with p53 in the PML nuclear body (PML-NB). The co-activatory role of PML depends on its ability to localize in the PML-NB. p53-dependent, DNA-damage-induced apoptosis, transcriptional activation by p53, the DNA-binding ability of p53, and the induction of p53 target genes such as Bax and p21 upon gamma-irradiation are all impaired in PML-/- primary cells. These results define a new PML-dependent, p53-regulatory pathway for apoptosis and shed new light on the function of PML in tumour suppression.

Loosening of sacral screw fixation under in vitro fatigue loading

Sacral screw fixation is frequently used for fusion of the lower lumbar spine, but sacral screws appear to offer less secure fixation than lumbar pedicle screws, and failure due to loosening under fatigue loading is common. The aim of this study was to examine in vitro the stability of medial and lateral bicortical and unicortical sacral screw fixation under a physiologically relevant fatigue-loading pattern. Bone mineral density, screw insertion torque, and screw-fixation stiffness were measured prior to cyclic loading between 40 and 400 N compression at 2 Hz for 20,000 cycles. The screw-fixation stiffness was measured every 500 cycles, and the axial pullout strength of the screws was recorded following loading. All of the lateral insertions loosened under the applied loading, but some of the medial insertions remained stable. Medial insertions proved stiffer and stronger than lateral insertions, and bicortical fixations were stronger than unicortical fixations. Bone mineral density and insertion torque were correlated with screw stiffness and pullout strength, although better correlation was found for insertion torque than bone mineral density. Bone mineral density is a good preoperative indicator of sacral screw-fixation strength, and insertion torque is a good intraoperative indicator. An insertion torque greater than 1.5 Nm is suggested as an indicative value for a stable medial unicortical insertion, whereas an insertion torque greater than 2 Nm suggests a stable medial bicortical insertion. It appears that, apart from the choice of technique (screw orientation and depth), minimizing the load on the screws during the initial part of the fusion process is also critical to maintain stability of the fused section and to obtain a solid fusion mass.

Bone mineral density variations along the lumbosacral spine

Vertebral bone quality is essential in vertebral strength and the stability of spinal screw fixation. A major factor of bone quality is the density of bone mineral and its distribution throughout the bone. There have been studies regarding bone mineral density variations in the cervical and thoracolumbar spine, but bone mineral density variations in the lumbosacral spine have not been documented. The purpose of the current study was to quantify bone mineral density variations at different lumbosacral levels and within vertebra, especially along the pathways of lumbar pedicle screws. Bone mineral density variations within the vertebrae along the lumbosacral spine were measured in 13 specimens from young male cadavers using peripheral quantitative computed tomography. Measurements included bone mineral density variations at different lumbosacral levels and in transverse layers and vertical columns within each vertebral body. These original data showed that the bone mineral density increased gradually from lumbar to S1 vertebrae, possibly reflecting a caudally increasing load on different lumbosacral levels. The highest bone mineral density in the lumbosacral spine is found at the pedicles and regions closest to pedicle bases, supporting the use of pedicle screw fixation.

Modes of baroreceptor-sympathetic coordination

We tested the hypothesis that the cardiac-related rhythm in sympathetic nerve discharge (SND) results from the forcing of a central oscillator to the frequency of the heart beat by pulse-synchronous baroreceptor afferent nerve activity. For this purpose, time series analysis was used to examine the phase relations between the brachial arterial pulse (AP) and cardiac-related activity recorded from the postganglionic inferior cardiac sympathetic nerve (CN) in urethan-anesthetized cats. Specifically, we made cycle-by-cycle measurements of peak systolic blood pressure, heart period, CN burst amplitude, and the phase angle (and corresponding interval) between peak systole and the next peak of CN activity. As the steady-state level of systolic blood pressure was raised by increasing the rate of a constant intravenous infusion of phenylephrine, we observed transitions from no phase-locking of CN activity to the AP to either phase-locking of variable strength or phase walk through part of the cardiac-cycle on the time scale of respiration. Phase walk is defined as a progressive and systematic change in the phase lag of cardiac-related CN activity relative to peak systole. Raising blood pressure strengthened phase-locking and either increased or decreased the mean interval between peak systole and the next peak of CN activity even when the change in heart period was small. CN burst amplitude and the interval between peak systole and the next peak of CN activity were inversely related, but the strength of the relationship varied considerably with experimental conditions. The relationship was strongest during phase walk. Step-wise increases in blood pressure induced by abdominal aortic obstruction led to an abrupt increase in the phase lag of CN activity relative to peak systole even when heart rate was not changed. We refer to such changes as sharp phase transitions that are a general property of dynamical nonlinear systems. The results support the view that the cardiac-related rhythm in SND is a forced nonlinear oscillation rather than the consequence of periodic inhibition of randomly generated activity.

Partial spectral analysis of cardiac-related sympathetic nerve discharge

We have studied the relationship between pulse synchronous baroreceptor input (represented by the arterial pulse, AP) and the cardiac-related rhythm in sympathetic nerve discharge (SND) of urethan-anesthetized cats by using partial autospectral and partial coherence analysis. Partial autospectral analysis was used to mathematically remove the portion of SND that can be directly attributed to the AP, while partial coherence analysis was used to removed the portion of the relationship between the discharges of sympathetic nerve pairs that can be attributed to linear AP-SND relationships that are common to the nerves. The ordinary autospectrum of SND (AS(SND)) and coherence functions relating the discharges of nerve pairs (Coh(SND-SND)) contained a peak at the frequency of the heart beat. When the predominant mode of coordination between AP and SND was a phase walk, partialization of the autospectra of SND with AP (AS(SND/AP)) left considerable power in the cardiac-related band. In contrast, when the predominant mode of coordination between AP and SND was phase-locking, there was virtually no cardiac-related activity remaining in AS(SND/AP). Partialization of Coh(SND-SND) with AP reduced the peak coherence within the cardiac-related band in both modes of coordination but to a much greater extent during phase-locking. After baroreceptor denervation, Coh(SND-SND) at the cardiac frequency remained significant, although a clear peak above background coherence was no longer apparent. These results are consistent with a model in which the central circuits controlling different sympathetic nerves share baroreceptor inputs and in addition are physically interconnected. The baroreceptor-sympathetic relationship contains both linear and nonlinear components, the former reflected by phase-locking and the latter by phase walk. The residual power in AS(SND/AP) during phase walk can be attributed to the nonlinear relationship, and the residual peak in partialized nerve-to-nerve coherence (Coh(SND-SND/AP)) arises largely from nonlinearities that are common to the two nerves. During both phase walk and phase-locking, in addition to common nonlinear AP-SND relationships, coupling of the central circuits generating the nerve activities may contribute to Coh(SND-SND/AP) because significant Coh(SND-SND) was still observed following baroreceptor denervation.

[Effect of domestic glutathione on the alcoholic liver disease]

OBJECTIVE

To evaluate the effect and safety of domestic glutathione (GSH) on serum ALT, AST, SB levels in alcoholic liver disease (ALD) by multicenter, randomized and TAD controlled trial.

METHODS

All the 110 patients with ALD enrolled had a history of drinking over 80g-120g daily for 5 years, and were randomized either into GSH (continuous infusion of 600g daily for 30d) or TAD (with the same dosage, course and route as GSH) group. The efficacy and safery were evaluated with clinical and biochemical (ALT, AST and GGT) parameters.

RESULTS

After 8 weeks of treatment, the clinical signs were improved at a different degree in both groups. ALT, AST and SB showed no significant difference in the two groups (the efficacy rate of 93% vs 96%, P>0.05).

CONCLUSION

The domestic GSH, with a good tolerance and safety, has a sound efficacy in the improvement of clinical signs and hepatic functions.

Differential pattern of spinal sympathetic outflow in response to stimulation of the caudal medullary raphe

In urethan-anesthetized cats, frequency domain analysis was used to explore the mechanisms of differential responses of inferior cardiac (CN), vertebral (VN), and renal (RN) sympathetic nerves to electrical stimulation of a discrete region of the medullary raphe (0-2 mm caudal to the obex). Raphe stimulation in baroreceptor-denervated cats at frequencies (7-12 Hz) that entrained the 10-Hz rhythm in nerve activity decreased CN and RN activities but increased VN activity. The reductions in CN and RN discharges were associated with decreased low-frequency (</=6 Hz) power and either increased (low stimulus intensity) or decreased (high stimulus intensity) 10-Hz band power. In contrast, VN 10-Hz band power was increased at all stimulus intensities, without changes in low-frequency power. High-frequency (25 Hz) stimulation decreased low-frequency activity of CN and RN discharges in both baroreceptor-denervated and baroreceptor-intact cats, without decreasing VN low-frequency activity. We propose that the differential pattern produced by raphe stimulation involves resonance at the level of the 10-Hz oscillators and differential inhibition of follower circuits that transmit both 10-Hz and low-frequency activity to sympathetic nerves.

Anti-HBV effect of targeted antisense RNA against HBV C gene

OBJECTIVE

To investigate the anti-HBV effect of targeted antisense RNA to hepatic cells.

METHODS

pREP4-aC which would transcript antisense RNA against HBV C gene in eukaryotic cells were delivered into 2.2.15 cells by glactosylated poly-L-lisine (Gal-PLL), and the positive cells were selected. HBsAg, HBeAg and HBV DNA produced by 2. 2.15 cells were detected with ELISA or Southern blot during the experiment, and the cytotoxicity of targeted antisense on 2.2.15 cells was observed.

RESULTS

The inhibition effect on HBsAg, HBeAg and HBV DNA occurred at the 24th hour after delivery and reached the highest level at the 6th day, and kept at lest two months. No cytotoxicity on 2.2.15 cells was observed.

CONCLUSION

The targeted antisense against HBV C gene by delivery of Gal-PLL could effectively inhibit the antigen expression of HBV and DNA replication.

[Three-dimensional reconstruction of internal auditory meatus and anatomical study of the inner structures]

OBJECTIVE

To provide anatomical basis for surgical operation in internal auditory meatus (IAM).

METHODS

Structures of cerebellopontine angle (CPA) and IAM in 25 temporal bone specimens (50 sides) fixed in formalin were measured. Three-dimensional reconstruction (3DR) of IAM in 13 normal adults (26 sides) was conducted using spiral CT scanning.

RESULTS

IAM took a conic shape with larger inside and smaller outside. The average width of IAM was (4.16 +/- 1.23) mm(2.87-6.83 mm) in horizontal dimension, the average height was (3.14 +/- 1.01) mm(2.23-4.45 mm) in vertical dimension, the average length was (8.67 +/- 2.31) mm (6.77-11.22 mm), the average volume was (98.23 +/- 16.56) mm3(67.44-133.21 mm3). There were 1-4 internal auditory arteries branched from the anterior-inferior cerebellar artery, which formed a vascular ansa near the opening of IAM. The average length of the facial nerve in IAM was (0.98 +/- 0.03) mm (0.89-1.07 mm), the average diameter of vestibulocochlear nerve was (1.67 +/- 0.05) mm (1.42-1.97 mm), the average diameter of the intermediate nerve (0.23 +/- 0.02) mm (0.19-0.26 mm).

CONCLUSION

It is necessary to pay attention to types of vascular ansa and relative nerve location in IAM during operation.

TT virus: a study of molecular epidemiology and transmission of genotypes 1, 2 and 3

BACKGROUND

TT virus (TTV) is a recently discovered virus, which is not related to any other known virus infecting humans.

OBJECTIVES

To investigate: (i) the world-wide distribution of the three major TTV genotypes; and (ii) the possible routes of viral transmission.

STUDY DESIGN

(i) The phylogenetic distribution of 494 TTV isolates originating from 31 countries was analysed, using partial ORF1 sequences. (ii) Faeces samples (n=22) and saliva samples (n=72) from French individuals were tested for the presence of TTV DNA. (iii) Viral titres in paired serum and saliva samples were compared.

RESULTS

(i) Genotypes 1, 2 and 3 were distributed world-wide, with a high proportion of type 1 in Asia (71%) and no type 3 identified in Africa to date. In the USA, 77% of isolates were grouped in four clusters only (genetic distances <10%). This was also the case of 76% of French isolates, 76% of Japanese isolates, and 89% of Hong Kong isolates. (ii) TTV DNA was detected in 18% of faeces samples and 68% of saliva samples tested. (iii) Viral titre in saliva samples was 100-1000 times higher than that of the corresponding serum.

CONCLUSIONS

(i) The observed epidemiological distribution of TTV isolates is compatible with an ancient dissemination of viral ancestors belonging to the different genotypes and a slow genetic evolution in sedentary populations. (ii) Besides the possible transmission of TTV by the parental and oral-faecal routes, the high titre of TTV DNA observed in saliva raises the hypothesis of the viral transmission by saliva droplets. This route of transmission could explain the high degree of exposure to viral infection observed in the general population.

Defenselike patterns of spinal sympathetic outflow involving the 10-Hz and cardiac-related rhythms

Frequency- and time-domain analyses were used to compare the effects of stimulation of the defense region of the midbrain periaqueductal gray (PAG) on the 10-Hz and cardiac-related discharges of sympathetic nerves with different cardiovascular targets. In baroreceptor-denervated cats anesthetized with urethan, PAG stimulation at frequencies equal to or higher (up to 25 Hz) than that of the free-running 10-Hz rhythm produced an immediate and sustained decrease in vertebral sympathetic nerve (VN) 10-Hz activity but increased the 10-Hz discharges of the inferior cardiac (CN) and renal (RN) nerves. In baroreceptor-innervated cats, VN cardiac-related activity was initially unchanged by high-frequency (25-Hz) PAG stimulation, or it increased along with that in the CN and RN. Later, during high-frequency PAG stimulation, when the rise in blood pressure approached its peak, VN cardiac-related activity usually was reduced below control level. At this time, the increases in CN and RN cardiac-related discharges were largely sustained. The cardiac-related discharges of the three nerves were unaffected by PAG stimulation at frequencies just below or just above that of the heartbeat. We conclude that the defenselike pattern of spinal sympathetic outflow involving the 10-Hz rhythm is different in mechanism and character from that involving the cardiac-related rhythm.

Presence of mitochondrial tRNA(Leu(UUR)) A to G 3243 mutation in DNA extracted from serum and plasma of patients with type 2 diabetes mellitus

AIMS/BACKGROUND

An A to G substitution at base pair 3243 in the mitochondrial tRNA(Leu(UUR)) gene (mt3243) is commonly associated with maternally inherited diabetes and deafness, and other diseases. It is possible that cell free mitochondrial DNA exists in serum and plasma from these patients, and these samples might be a source of material for the detection of such mutations.

METHODS

Sixteen patients with type 2 diabetes mellitus and 25 healthy subjects were tested for the 3243 mutation by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis. Plasma and serum from the 41 subjects were tested blind, without knowledge of the final diagnosis.

RESULTS

PCR amplification of the mtRNA(Leu(UUR)) region in mitochondrial DNA (mtDNA) in serum samples revealed the presence of mtDNA in all samples. After ApaI digestion of the amplified DNA fragments, mt3243 was detected in the serum and plasma samples of the seven patients with diabetes who had previously been found to have this mutation in their leucocyte DNA. None of the serum/plasma samples from the healthy subjects or those patients negative for mt3243 in their leucocytes had this mutation (p < 0.001). In addition, the degree of heteroplasmy of mt3243 appeared to be higher in serum and plasma samples than in leucocytes among mt3243 carriers (p < 0.05).

CONCLUSIONS

Therefore, mtDNA and associated mutations are present and detectable in serum and plasma. Plasma and serum might be alternative sources for the molecular diagnosis of mt3243 associated diabetes mellitus, as well as other mitochondrial mediated diseases.

Role of SUMO-1-modified PML in nuclear body formation

The tumor-suppressive promyelocytic leukemia (PML) protein of acute promyelocytic leukemia (APL) has served as one of the defining components of a class of distinctive nuclear bodies (NBs). PML is delocalized from NBs in APL cells and is degraded in cells infected by several viruses. In these cells, NBs are disrupted, leading to the aberrant localization of NB proteins. These results have suggested a critical role for the NB in immune response and tumor suppression and raised the question of whether PML is crucial for the formation or stability of NB. In addition, PML is, among other proteins, covalently modified by SUMO-1. However, the functional relevance of this modification is unclear. Here, we show in primary PML(-/-) cells of various histologic origins, that in the absence of PML, several NB proteins such as Sp100, CBP, ISG20, Daxx, and SUMO-1 fail to accumulate in the NB and acquire aberrant localization patterns. Transfection of PML in PML(-/-) cells causes the relocalization of NB proteins. By contrast, a PML mutant that can no longer be modified by SUMO-1 fails to do so and displays an aberrant nuclear localization pattern. Therefore, PML is required for the proper formation of the NB. Conjugation to SUMO-1 is a prerequisite for PML to exert this function. These data shed new light on both the mechanisms underlying the formation of the NBs and the pathogenesis of APL. (Blood. 2000;95:2748-2752)

The transcriptional role of PML and the nuclear body

The PML gene encodes a tumour suppressor protein associated with a distinct subnuclear domain, the nuclear body. Various functions have been attributed to the PML nuclear body, but its main biochemical role is still unclear. Recent findings indicate that PML is essential for the proper formation of the nuclear body and can act as a transcriptional co-factor. Here we summarize the current understanding of the biological functions of PML and the nuclear body, and discuss a role for these intra-nuclear structures in the regulation of transcription.

Pattern selection induced by electroconvection in the electrodeposition of iron

The morphology of iron electrodeposit is shown to relate closely to the pH of the electrolyte solution. Macroscopically, depending on the strength of the interbranch convection, which is associated with the concentration of H3O+ in the electrolyte, the deposit morphology varies from treelike pattern to meshlike pattern and dense-branching morphology. Microscopically the deposit is ramified and dense-branching at lower concentration of H3O+, while it becomes relatively smooth and stringy at higher H3O+ concentration. The symmetry of the convective vortices on the two sides of the growing tip is observed to decide the growth behavior of the tip. We suggest that H3O+ influences the pattern formation and pattern selection in the electrodeposition of iron from FeSO4 solution by either initiating interbranch convection or changing the effective interfacial energy of the deposit and the electrolyte.

The effects of cyclic loading on pull-out strength of sacral screw fixation: an in vitro biomechanical study

STUDY DESIGN

The pull-out strength of sacral screw fixation after cyclic loading was tested using young human cadaveric specimens.

OBJECTIVES

To evaluate the effects of fatigue loading on the pull-out strength of medial and lateral unicortical and bicortical sacral screws and to correlate the pull-out strength with sacral bone density and the screw insertion torque.

SUMMARY OF BACKGROUND DATA

The immediate biomechanical effects of depth of penetration, screw orientation, and bone density on sacral screw fixation have been studied in aged cadaveric specimens. The effect of cyclic loading on the pull-out strength of sacral screw fixation is unknown, however, and data from young specimens is rare.

METHODS

Eleven fresh specimens of human sacrum were used in this study. Bone mineral density at the vertebral body and the ala were determined by peripheral quantitative computed tomography. Seven-millimeter compact Cotrel-Dubousset sacral screws were inserted into the sacrum anteromedially and anterolaterally, both unicortically and bicortically, and the insertion torque for each screw was measured. Cyclic loading from 40 to 400 N was applied to each screw at a frequency of 2 Hz up to 20,000 cycles. Pull-out tests were conducted after completion of the fatigue tests.

RESULTS

The average bone density was 0.38 +/- 0.08 g/mL at the S1 body and 0.24 +/- 0.05 g/mL at the S1 ala. The insertion torque and average pull-out force after cyclic loading were significantly higher for bicortical fixation than for unicortical fixation for a particular screw alignment. The pull-out strength and insertion torque of medially oriented fixation was always higher than that for lateral fixation, however, regardless of whether the insertion was unicortical or bicortical. The pull-out force of unicortical and bicortical medial screw fixations after cyclic loading showed significant linear correlations with both the insertion torque and the bone mineral density of the S1 body.

CONCLUSIONS

In a young population, screw orientation (anterolateral or anteromedial) was more important in determining pull-out strength than screw depth (unicortical or bicortical) after fatigue loading, anteromedially directed screws being significantly stronger than laterallyplaced screws. Bone mineral density of the S1 body andinsertion torque were good preoperative and intraoperative indicators of screw pull-out strength.

Purification of the newly found selenium-containing proteins in the arterial wall and brain of the rat

Previously several selenium-containing proteins with different subunit molecular masses (M(r)) were detected in the arterial wall and brain of rats. In continuation of this work, after labeling of rats in vivo with [(75)Se]selenite, the new selenium-containing proteins of interest were purified on a Sephadex G-200 column followed by preparative isoelectric focusing. Nuclear analytical methods (gamma-counter and gamma-detector) were applied in the detection and identification of the (75)Se-labeled proteins. The two (75)Se-containing proteins from the arterial wall migrated as 15.0- and 67.0-kDa species on SDS-PAGE gels with pI values of 4.5 and 5.1, respectively. The three (75)Se-containing proteins from brain purified to homogeneity had M(r) values of 18.0, 30.0, and 42.9 kDa and pI values of 6.3, 6.5, and 6.0, respectively. Of these proteins, the 67.0-, 42.9-, and 30.0-kDa species may be yet not characterized selenoproteins with important biological functions.

Internal structure and early thermal evolution of Mars from Mars Global Surveyor topography and gravity

Topography and gravity measured by the Mars Global Surveyor have enabled determination of the global crust and upper mantle structure of Mars. The planet displays two distinct crustal zones that do not correlate globally with the geologic dichotomy: a region of crust that thins progressively from south to north and encompasses much of the southern highlands and Tharsis province and a region of approximately uniform crustal thickness that includes the northern lowlands and Arabia Terra. The strength of the lithosphere beneath the ancient southern highlands suggests that the northern hemisphere was a locus of high heat flow early in martian history. The thickness of the elastic lithosphere increases with time of loading in the northern plains and Tharsis. The northern lowlands contain structures interpreted as large buried channels that are consistent with northward transport of water and sediment to the lowlands before the end of northern hemisphere resurfacing.

Frequent integration of precore/core mutants of hepatitis B virus in human hepatocellular carcinoma tissues

The development of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) frequently follows persistent HBV infection and may arise in individuals who are hepatitis B e antigen (HBeAg) negative, indicating the possible presence of precore/core mutants. It is unclear whether precore/core mutants are associated with tumour development or are selected for after chromosomal integration of the wild-type viral DNA. We studied the status and sequence variation of the precore/core region of HBV in 56 patients with HBV-associated HCC and in various corresponding non-tumour tissues by Southern blot analysis, polymerase chain reaction and direct sequencing. Southern blot showed that integrated HBV DNA existed in 43 of 56 HCC tissues. Sequence analysis revealed mutations in 65% of the HCC (26/40) and 45% (14/31) of the corresponding non-tumour tissues. The mutation at nucleotide (nt) 1896, known to prevent HBeAg synthesis, was detected in 40% (16/40) of the tumours and in 35.4% (11/31) of the non-tumour tissues. Other mutations were found at nt 1899 (eight of 40 in HCC; three of 31 in non-tumour tissues), nt 1898 (seven of 40 in HCC; two of 31 in non-tumour tissues), nt 1912 (seven of 40 in HCC; none of 31 in non-tumour tissues) and nt 1886 (three of 40 in HCC; none of 31 in non-tumour tissues). To determine whether this finding merely reflected the prevalence of such mutants in this geographical region, HBV DNA from the sera of patients (also in this region) with acute and chronic hepatitis were sequenced. The nt 1896 mutant was found in 5.6% (one of 18) of patients with acute hepatitis B and in 22.8% (nine of 35) of patients with chronic hepatitis B. However, the nt 1898 mutation was not found in any of these sera. The precore/core mutant was observed with increasing frequency from acute hepatitis to chronic hepatitis, non-tumour and HCC, and this difference in frequency was significant between HCC and acute hepatitis B groups (P < 0.01), suggesting that the precore/core mutant or hepatocytes harbouring this mutant may be under immune selection and that such mutations may facilitate integration and subsequent tumour development.

[Applied anatomy of the transverse rectus abdominis musculocutaneous (TRAM) flap in relation to the eleventh or twelfth thoracic nerve]

OBJECTIVE

To observe the distribution of the terminal branches of the eleventh and twelfth thoracic nerve(T11, T12) for the anatomical basis and operation key points of the transverse rectus abdominis musculocutaneous(TRAM) flap with T11, T12.

METHODS

The anterior abdominal wall was investigated through anatomical dissection in 22 embalmed cadavers.

RESULTS

Cutaneous nerve distribution in the TRAM flap came mainly from T11, T12. They run obliquely between transverse abdominis and obliquus internus abdominis muscle. At the lateral edge of the rectus abdominis, they piece the anterior rectus sheath into the muscle. While supplying the muscle they pass on to supply the anterior rectus sheath and the overlying skin.

CONCLUSION

It is possible to preserve T11, T12 in the TRAM flap, which would favour rapid return of flap sensation.

Hepatitis B virus reactivation in patients undergoing cytotoxic chemotherapy for solid tumours: precore/core mutations may play an important role

Reactivation of the hepatitis B virus (HBV) is a rare, but well described complication of cytotoxic chemotherapy that may result in hepatic failure. Patients who are chronic carriers of the HBV and who have a G to A mutation at nucleotide 1896 in the precore region may develop more severe liver disease, possibly because of rapid selection and enhanced replication ability of the mutant strain. Such mutant viruses have been implicated occasionally in chemotherapy induced reactivation of hepatitis B virus. In this report, 5 patients with solid tumours were identified to have developed severe hepatitis B virus related liver disease during treatment with cytotoxic agents (with dexamethasone as anti-emetic). All had clinical and serological evidence of reactivation of the HBV. Three patients developed icteric hepatitis; 2 fully recovered, and 1 had died from progressive metastatic disease while recovering from the reactivation. The other two died from progressive liver failure. Direct sequencing of the polymerase chain reaction (PCR) products of the precore (preC) and precore promoter region of the HBV-DNA was carried out on the patients' serum samples taken during the episode of reactivation. In each case, similar mutations (G to A) in nucleotide 1896 of the preC region were found, together with additional mutations in the preC promoter. The present findings suggest that reactivation involving a mutant hepatitis B virus may lead to liver failure, which is possibly more severe than that caused by wild type HBV, and can be triggered by cytotoxic chemotherapy, or the administration of corticosteroids. In Eastern Asia the HBV carriage rate in adults is high. HBV reactivation and severe liver disease during cytotoxic treatment may become a serious and common problem in this region as cytotoxic chemotherapy is more widely used. Patients should be screened routinely for HBsAg in endemic areas of chronic hepatitis B virus infection prior to receiving cytotoxic treatment. The possibility of HBV reactivation should be considered in patients developing liver dysfunction. Patients who are HBeAg negative/Anti-HBe positive, and are suspected to be having an HBV reactivation, should have HBV-DNA levels measured for confirmation as they may carry a mutant HBV.

Variation in bone mineral density of the sacrum in young adults and its significance for sacral fixation

STUDY DESIGN

Bone mineral density variations throughout the sacrum were measured and correlated with sacral screw insertion torque.

OBJECTIVE

To quantify bone mineral density variations within the S1 body and ala of young human specimens, especially along the pathways of sacral screws, and to examine the relation between sacral screw fixation and bone mineral density.

SUMMARY OF BACKGROUND DATA

Vertebral bone quality is an essential factor in anterior or posterior screw fixation of the spine. Several studies have been conducted regarding bone mineral density variations in the cervical and thoracolumbar spine. However, such variations in bone mineral density in the sacrum have not been well documented.

METHODS

The bone mineral density of 13 sacral specimens from young male cadavers (mean age, 31 years) was measured using highly accurate quantitative computed tomography. Variations in bone mineral density were measured in five transverse layers and seven vertical columns within the S1 body, and in four transverse layers and six vertical columns within the ala. The sacral screw insertion torque was measured (unicortical and bicortical), and the correlation with bone mineral density was calculated.

RESULTS

The mean bone mineral density of the S1 body was 381.9 +/- 59 mg/cm3, which was 31.9% higher than that of the sacral ala (mean, 296.9 +/- 86 mg/cm3) (P < 0.05). Bone mineral density of the superior sacral endplate was higher than that of any other transverse layer. Columns near the lateral posterior and lateral anterior of the S1 body had the highest bone mineral density. In the ala, bone mineral density values of the internal columns (pedicle) were the highest. Screw insertion torque for bicortical purchase along the S1 pedicle correlated well with the bone mineral density of the S1 body (r = 0.67, P < 0.05).

CONCLUSION

This study quantified the volumetric bone mineral density variations within the S1 body and ala, and a significant linear correlation between the screw insertion torque and bone mineral density was found. Optimal sacral screw insertion pathways were also outlined based on bone mineral density values.

Pancreatic insulinomas: experience in 220 patients

OBJECTIVE

To summarize the experience in the diagnosis and treatment of insulinoma.

METHODS

We retrospectively reviewed 220 patients with insulinoma confirmed surgically in the PUMC Hospital from 1953 to 1999. They were 131 men and 89 women, aged on average 39 years.

RESULTS

In the 220 patients, the average interval from the onset of symptoms to diagnosis was 35 months. 54% of the patients were misdiagnosed before admission to the hospital. In 214 patients underwent operation, 201 (93.9%) had benign tumor and 12 (5.6%) malignant one. The diameter of 78% tumors was less than 2cm. 90.7% tumors were single and 9.3% were multiple. 37.1% tumors were located in the head and uncinate process of the pancreas, 26.1% in the body, 36.1% in the tail, and 0.7% ectopic. 95.5% patients had Whipple's triad and the ratio of insulin to glucose was greater than 0.3 in 89% patients. The positive rates of B-ultrasound, CT and MRI for localization before operation were low, but those of angiography and PTPC were 62.8% and 88% respectively. Most patients could be cured by simple enucleation of tumor. The main complications were pancreatic fistulae and pancreatitis.

CONCLUSION

It is important for surgeons to familiarize with insulinoma, the most common islet cell tumor, for a better treatment.

A role for PML and the nuclear body in genomic stability

The PML gene of acute promyelocytic leukemia (APL) encodes a cell-growth and tumor suppressor. PML localizes to discrete nuclear bodies (NBs) that are disrupted in APL cells. The Bloom syndrome gene BLM encodes a RecQ DNA helicase, whose absence from the cell results in genomic instability epitomized by high levels of sister-chromatid exchange (SCE) and cancer predisposition. We show here that BLM co-localizes with PML to the NB. In cells from persons with Bloom syndrome the localization of PML is unperturbed, whereas in APL cells carrying the PML-RARalpha oncoprotein, both PML and BLM are delocalized from the NB into microspeckled nuclear regions. Treatment with retinoic acid (RA) induces the relocalization of both proteins to the NB. In primary PML-/- cells, BLM fails to accumulate in the NB. Strikingly, in PML-/- cells the frequency of SCEs is increased relative to PML+/+ cells. These data demonstrate that BLM is a constituent of the NB and that PML is required for its accumulation in these nuclear domains and for the normal function of BLM. Thus, our findings suggest a role for BLM in APL pathogenesis and implicate the PML NB in the maintenance of genomic stability.

A RA-dependent, tumour-growth suppressive transcription complex is the target of the PML-RARalpha and T18 oncoproteins

PML and Tif1a are fused to RARA and Braf, respectively, resulting in the production of PML-RARalpha and Tif1alpha-B-Raf (T18) oncoproteins. Here we show that PML, Tif1alpha and RXRalpha/RARalpha function together in a transcription complex that is dependent on retinoic acid (RA). We found that PML acts as a ligand-dependent coactivator of RXRalpha/RARalpha. PML interacts with Tif1alpha and CBP. In Pml-/- cells, the RA-dependent induction of genes such as RARB2 and the ability of Tif1alpha and CBP to act as transcriptional coactivators on RA are impaired. We show that both PML and Tif1alpha are growth suppressors required for the growth-inhibitory activity of RA. T18, similar to PML-RARalpha, disrupts the RA-dependent activity of this complex in a dominant-negative manner resulting in a growth advantage. Our data define a new pathway for the control of cell growth and tumorigenesis, and provide a new model for the pathogenesis of acute promyelocytic leukaemia (APL).

Particulate Air Pollution in Mexico City: A Collaborative Research Project

PM₁₀, PM₂₅, precursor gas, and upper-air meteorological measurements were taken in Mexico City, Mexico, from February 23 to March 22, 1997, to understand concentrations and chemical compositions of the city's particulate matter (PM). Average 24-hr PM₁₀ concentrations over the period of study at the core sites in the city were 75 H g/m³. The 24-hr standard of 150 μ g/m³ was exceeded for seven samples taken during the study period; the maximum 24-hr concentration measured was 542 μ g/m³. Nearly half of the PM₁₀ was composed of fugitive dust from roadways, construction, and bare land. About 50% of the PM₁₀ consisted of PM_2.5, with higher percentages during the morning hours. Organic and black carbon constituted up to half of the PM_2.5. PM concentrations were highest during the early morning and after sunset, when the mixed layers were shallow. Meteorological measurements taken during the field campaign show that on most days air was transported out of the Mexico City basin during the afternoon with little day-to-day carryover.

Intraoperative ultrasound for hepatic neoplasm during surgery

OBJECTIVE

The purpose of this study was to determine the impact of intraoperative ultrasound (IOUS) on the management of patients with neoplasms of the liver.

METHODS

Forty-nine patients operated on for liver or other pathologic processes were examined intraoperatively with 5.0 MHz special ultrasound transducers during surgical exploration of the abdomen. Subjects were evaluated because of known or suspected disease of the liver. Preoperative imaging studies included percutaneous ultrasound (n = 49), magnetic resonance imaging (n = 11), and computed tomography (n = 34). Intraoperative evaluation on all patients included inspection, bimanual palpation, and ultrasonography. Comparison between preoperative imagings and IOUS were analysed.

RESULTS

Sensitivity for detection of hepatic neoplasms showed in intraoperative ultrasound, percutaneous ultrasound, magnetic resonance imaging and computed tomography as 100% (23/23), 74% (17/23), 74% (14/19) and 75% (6/8). Specificity showed 100% (26/26), 100% (26/26), 93% (14/15) and 67 (2/3). In seven patients (14%), the neoplasms were not found by inspection, bimanual palpation, and identified only by IOUS.

CONCLUSIONS

Intraoperative ultrasound is the most sensitive and specific method for detection and surgery of liver neoplasms, especially the occult neoplasms and small size lesion (< 2 cm).

[Applied anatomy on musclebone flap of hyoideumomohyoid to renovate vocal fold]

OBJECTIVE

In order to provide anatomical basis for renovating vocal fold with muscle-bone flap of hyoideum-omohyoid.

METHOD

It was measured that the anatomical structure correlative with superior belly of hyoideum-omohyoid, artery, vein and nerve of the muscle and vocal fold morphosis by 26(52 sides) cephalocevical sample dissection.

RESULT

It was observed that the muscle is 74.8 mm in length, 8.4 mm in width of starting part, 9.6 mm in width of middle part, 4.4 mm in width of tendon part. Its blood supply are mainly from cricothyriod artery (51.9%) and superior laryngeal artery (25.0%) with an arterial trunk of 9.8 mm in length and 0.7 mm in diameter. The venous trunk is 17.4 mm in length and 1.1 mm in diameter. The muscle is innervated by the sub-broaches arising from hypoglossal nerve ansa, the trunk is 19.6 mm in length and 0.6 mm in diameter.

CONCLUSION

It is possible that musclebone flap of hyoideumomohyoid to renovate vocal fold according to the study of the muscle morphology characteristic.

Differential patterns of spinal sympathetic outflow involving a 10-Hz rhythm

Time and frequency domain analyses were used to examine the changes in the relationships between the discharges of the inferior cardiac (CN) and vertebral (VN) postganglionic sympathetic nerves produced by electrical activation of the midbrain periaqueductal gray (PAG) in urethan-anesthetized, baroreceptor-denervated cats. CN-VN coherence and phase angle in the 10-Hz band served as measures of the coupling of the central oscillators controlling these nerves. The 10-Hz rhythm in CN and VN discharges was entrained 1:1 to electrical stimuli applied to the PAG at frequencies between 7 and 12 Hz. CN 10-Hz discharges were increased, and VN 10-Hz discharges were decreased when the frequency of PAG stimulation was equal to or above that of the free-running rhythm. In contrast, stimulation of the same PAG sites at lower frequencies increased, albeit disproportionately, the 10-Hz discharges of both nerves. In either case, PAG stimulation significantly increased the phase angle between the two signals (VN 10-Hz activity lagged CN activity); coherence values relating their discharges were little affected. However, the increase in phase angle was significantly more pronounced when the 10-Hz discharges of the two nerves were reciprocally affected. Importantly, partialization of the phase spectrum using the PAG stimuli did not reverse the change in CN-VN phase angle. This observation suggests that the increase in the CN-VN phase angle reflected changes in the phase relations between coupled oscillators in the brain stem rather than the difference in conduction times to the two nerves from the site of PAG stimulation. In contrast to the effects elicited by PAG stimulation, stimulation of the medullary lateral tegmental field induced uniform increases in the 10-Hz discharges of the two nerves and no change in the CN-VN phase angle. Our results demonstrate that changes in the phase relations among coupled brain stem 10-Hz oscillators are accompanied by differential patterns of spinal sympathetic outflow. The reciprocal changes in CN and VN discharges produced by PAG stimulation are consistent with the pattern of spinal sympathetic outflow expected during the defense reaction.

Detection of apolipoprotein B mRNA editing by peptide nucleic acid mediated PCR clamping

Apolipoprotein B (apoB) mRNA editing leads to a single base change in its mRNA and the production of apoB-48. Currently, the degree of apoB mRNA editing is analyzed by the RT-PCR primer extension method. While this method is quantitative, it is labor intensive, utilizes radioactivity for labeling and may not be sensitive enough to discriminate between low levels of editing and inherent assay background levels. Peptide nucleic acid (PNA) oligonucletides have been used in single point mutation detection through PCR clamping. In the present work, we developed a PCR based assay which can detect the single base change responsible for the apoB-48 production. We found that as low as 0.5% of the edited form can be clearly detected by PNA mediated PCR clamping. When combined with the primer extension assay, an approximately 180-fold enrichment of the edited percentage is observed, reflecting selected PCR amplification of templates containing the edited base.

[Evaluation of intraoperative ultrasonography for hepatic neoplasm in surgery]

OBJECTIVE

The purpose of this study was to evaluate the impact of intraoperative ultrasound (IOUS) on the management of patients with neoplasms of the liver.

METHODS

Forty-nine patients received operations for liver tumors were examined intraoperatively with 5.0 MHz special ultrasound transducers during surgical exploration of the abdomen. Preoperative imaging studies including percutaneous ultrasound (n = 49), magnetic resonance imaging (n = 11), and computed tomography (n = 34) were taken to compare with intraoperative ultrasonography for the evaluation.

RESULTS

Sensitivity for detection of hepatic neoplasms showed in intraoperative ultrasound, percutaneous ultrasound, magnetic resonance imaging and computed tomography as 100%(23/23), 74%(17/23), 74%(14/19), and 75%(6/8) respectively. Specificity showed 100%(26/26), 100%(26/26), 93%(14/15), and 67(2/3) respectively.

CONCLUSIONS

Intraoperative ultrasound was the most sensitive and specific method for detection and surgery of liver neoplasms, especially the occult neoplasms and small size lesion (< 2 cm).

ApoA-II maintains HDL levels in part by inhibition of hepatic lipase. Studies In apoA-II and hepatic lipase double knockout mice

High density lipoprotein (HDL) cholesterol levels are inversely related to the risk of developing coronary heart disease. Apolipoprotein (apo) A-II is the second most abundant HDL apolipoprotein and apoA-II knockout mice show a 70% reduction in HDL cholesterol levels. There is also evidence, using human apoA-II transgenic mice, that apoA-II can prevent hepatic lipase-mediated HDL triglyceride hydrolysis and reduction in HDL size. These observations suggest the hypothesis that apoA-II maintains HDL levels, at least in part, by inhibiting hepatic lipase. To evaluate this, apoA-II knockout mice were crossbred with hepatic lipase knockout mice. Compared to apoA-II-deficient mice, in double knockout mice there were increased HDL cholesterol levels (57% in males and 60% in females), increased HDL size, and decreased HDL cholesteryl ester fractional catabolic rate. In vitro incubation studies of plasma from apoA-II knockout mice, which contains largely apoA-I HDL particles, showed active lipolysis of HDL triglyceride, whereas similar studies of plasma from apoA-I knockout mice, which contains largely apoA-II particles, did not. In summary, these results strongly suggest that apoA-II is a physiological inhibitor of hepatic lipase and that this is at least part of the mechanism whereby apoA-II maintains HDL cholesterol levels.

Hepatitis B envelope protein mutants in human hepatocellular carcinoma tissues

Hepatitis B virus (HBV) envelope mutants in the region encoding the highly immunogenic major hydrophilic region (MHR) of surface antigen (HBsAg) have been associated with vaccine failure and chronic infection. To determine if these mutants are associated with the development of human hepatocellular carcinoma (HCC), we measured the frequency and nature of such mutants in 23 HBV-associated HCC and various control tissues by performing Southern blot analysis, the polymerase chain reaction (PCR) and direct sequencing. The HBV genome was present mainly in an integrated form and, in most of the samples, the envelope gene was intact. Amino acid substitutions, involving the MHR region in the HCC tissues, were analysed in 11 (61. 1%) of 18 patients with HCC. The mutation Gly145Arg, which has been reported to be associated with immunoevasion, was found in seven of the 18 HCC tissues. A significantly higher frequency of mutations was found in HCC tissues (11 of 18) than in the corresponding non-tumorous tissue of the same patients (one of eight), and in samples from patients with acute (one of 19) or chronic (three of 31) HBV infection (P < 0.001, Fisher's exact test). The accumulation of these envelope mutants in the HCC tissue suggests that such envelope protein mutations may play a role in the process of oncogenesis and that specific vaccines may need to be developed to prevent the occurrence of mutant HBV-associated HCC. Alternatively, the progressive accumulation of mutants in patients with acute hepatitis, chronic hepatitis and HCC may reflect the increased length of duration of HBV infection in these groups of liver lesions.

Lymphohematopoietic stem cell engraftment

Traditional dogma has stated that space needs to be opened by cytoxic myeloablative therapy in order for marrow stem cells to engraft. Recent work in murine transplant models, however, indicates that engraftment is determined by the ratio of donor to host stem cells, i.e., stem cell competition. One hundred centigray whole body irradiation is stem cell toxic and nonmyelotoxic, thus allowing for higher donor chimerism in a murine syngeneic transplant setting. This nontoxic stem cell transplantation can be applied to allogeneic transplant with the addition of a tolerizing step; in this case presensitization with donor spleen cells and administration of CD40 ligand antibody to block costimulation. The stem cells that engraft in the nonmyeloablated are in G0, but are rapidly induced (by 12 hours) to enter the S phase after in vivo engraftment. Exposure of murine marrow to cytokines (IL-3, IL-6, IL-11 and steel factor) expands progenitor clones, induces stem cells into cell cycle, and causes a fluctuating engraftment phenotype tied to phase of cell cycle. These data indicate that the concepts of stem cell competition and fluctuation of stem cell phenotype with cell cycle transit should underlie any new stem cell engraftment strategy.

Traumatic instabilities of the cervical spine caused by high-speed axial compression in a human model. An in vitro biomechanical study

STUDY DESIGN

Traumatic injury of the cervical spine was produced on human cadavers and evaluated with instability tests and radiographs.

OBJECTIVE

To relate traumatic injuries of the cervical spine to instability and patterns of traumatic injury to different levels of impact energy.

SUMMARY OF BACKGROUND DATA

Data from young human cadavers are rare in traumatic models of the cervical spine, and instabilities caused by axial compression with different impacts remain unknown.

METHODS

Fourteen cervical spine specimens (C2-C4) obtained from fresh human cadavers were divided evenly into two groups and subjected to axial compressive impact with 30 J and 50 J impact energy, respectively. Pure moments in flexion-extension, left/right lateral bending, and left/right axial rotation were applied to each specimen before and after trauma. The maximum moment was 2.0 Nm in each case. Ranges of motion and neutral zones were measured using stereophotogrammetry.

RESULTS

Ranges of motion and neutral zones for both groups increased after trauma. No bony injury was observed on the radiographs after trauma with 30 J, but motions increased significantly in flexion, extension, and axial rotation. All specimens showed bony injuries after trauma with 50 J, whereas motions continued to increase significantly in all directions. The relative neutral zone values were larger than the corresponding range of motion values, except in flexion-extension after trauma with 50 J.

CONCLUSIONS

The injury patterns of the cervical spine were associated with impact energy, and a high level of impact energy could produce either three-column injury or anterior middle-column injury. Instabilities of the cervical spine caused by compressive trauma increased with the level of impact energy. The neutral zone was more sensitive than the range of motion in representing spinal instability, whereas instability testing was more sensitive than radiographs in evaluating traumatic injury of cervical spine.

Human brain alpha rhythm: nonlinear oscillation or filtered noise?

The mechanism for generation of the alpha rhythm is controversial. In the current study, analysis in the time and frequency domains revealed that the alpha rhythm recorded from the scalp overlying the human occipital cortex can be entrained to the second or third harmonic of low frequency light flashes. These results support the view that the alpha rhythm is generated by a nonlinear oscillator rather than a narrow-band transmission system acting as a filter.

RB regulates the stability and the apoptotic function of p53 via MDM2

The binding of RB to MDM2 is shown to be essential for RB to overcome both the antiapoptotic function of MDM2 and the MDM2-dependent degradation of p53. The RB-MDM2 interaction does not prevent MDM2 from inhibiting p53-dependent transcription, but the RB-MDM2 complex still binds to p53. Since RB specifically rescues the apoptotic function but not the transcriptional activity of p53 from negative regulation by MDM2, transactivation by wild-type p53 is not required for the apoptotic function of p53. However, an RB-MDM2-p53 trimeric complex is active in p53-mediated transrepression. These data link directly the function of two tumor suppressor proteins and demonstrate a novel role of RB in regulating the apoptotic function of p53.

[The applied anatomy of the periosteal flap composed of submental artery and dgastric muscle]

OBJECTIVE

To provide anatomical basis for a new style operation using periosteal flap composed of submental artery, anteroventral portion of digastric muscle and submental artery for the renovation of laryngotrachea.

METHODS

The anatomical structures correlative with submental artery, submental vein, anteroventral portion of digastric muscle and mandibular periosteum in 23 (46 sides) cephalocervical samples were measured.

RESULTS

The periosteal flaps had shown many advantages inculding large transfer capacity, rich blood supply, flexibility.

CONCLUSION

It is feasible that the periosteal flap composed of submental artery, anteroventral portion of digastric muscle and mandibular periosteum is useful laryngotracheal renovation.

PML is essential for multiple apoptotic pathways

The PML gene of acute promyelocytic leukaemia (APL) encodes a cell growth and tumour suppressor, however, the mechanisms by which PML suppresses tumorigenesis are poorly understood. We show here that Pml is required for Fas- and caspase-dependent DNA-damage-induced apoptosis. We also found that Pml is essential for induction of programmed cell death by Fas, tumour necrosis factor alpha (TNF), ceramide and type I and II interferons (IFNs). As a result, Pml-/- mice and cells are protected from the lethal effects of ionizing radiation and anti-Fas antibody. Pml is required for caspase 1 and caspase 3 activation upon exposure to these stimuli. The PML-RAR alpha fusion protein of APL renders haemopoietic progenitor cells resistant to Fas-, TNF- and IFN-induced apoptosis with a lack of caspase 3 activation, thus acting as a Pml dominant-negative product. These results demonstrate that Pml is a mediator of multiple apoptotic signals, and implicate inhibition of apoptosis in the pathogenesis of APL.