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.

Comparison of the strengths of lumbosacral fixation achieved with techniques using one and two triangulated sacral screws

STUDY DESIGN

The strength of sacral screw fixation achieved with techniques using one sacral screw and two triangulated sacral screws with Chopin block was tested on 10 fresh human sacrum specimens.

OBJECTIVES

To compare the stiffness and the failure strength of single sacral screw fixation and those of two divergent triangulated sacral screw fixation under different loading conditions.

SUMMARY OF BACKGROUND DATA

Weak sacral screw fixation is the major cause of failure in instrumented lumbosacral fusion. Although previous studies have evaluated the strength of anteromedially and anterolaterally inserted sacral screws, the strength of two divergent triangulated sacral screws has not been evaluated biomechanically. It is assumed that increasing the number of sacral screws and using a triangulated insertion technique may increase the strength of purchase for lumbosacral fixation.

METHODS

Ten fresh human sacrum specimens were used in this study. Six specimens were from donors less than 30 years of age (younger group), and the other four were from donors more than 60 years of age (aged group). The specimens were assigned randomly to either one side one S1 pedicle screw inserted anteromedially or to the other side with two screws directed anteromedially and anterolaterally. All specimens were tested with an Instron material testing machine (Instron Limited, High Wycombe, England). The average stiffness under compression, tension, and torsion were calculated from the average slopes of the load deformation curves. The failure load was applied for the final testing.

RESULTS

The results showed significant differences in stiffness between fixation with one screw and fixation with two divergent triangulated screws. With one S1 pedicle screw fixation, the average stiffness was 203 N/mm for compression, 147 N/mm for tension, and 2 Nm/degree for torsion. With two-screw fixation the average stiffness increased to 255 N/mm (126%), 185 N/mm (126%) and 2.4 Nm/degree (120%), respectively. The average failure strength under tension loads was found to be 1450 N in the younger specimens and was reduced to 980 N in the aged specimens.

CONCLUSION

This study showed that fixation with two divergent triangulated screws to the sacrum was significantly stronger than one-screw fixation for lumbosacral fusion. The strength of fixation seems to have a negative correlation with aging.

Nonlinear interactions of slow and rapid rhythms in sympathetic nerve discharge

We used bispectral analysis to characterize the nonlinear interactions of the respiratory-related (RR), cardiac-related (CR), or 10-Hz rhythms in sympathetic nerve discharge (SND) of urethan-anesthetized cats. Bispectral analysis investigates relationships among frequency triples in the same signal (inferior cardiac postganglionic SND) where the third frequency is the sum of the other two due to quadratic nonlinear coupling. Coupling of the RR and CR rhythms leading to the generation of new components (i.e., modulated frequencies) in SND occurred in 84% of the total cases, whereas the incidence was 71% for the RR and 10-Hz rhythms. The occurrence of such nonlinear interactions implies that the RR, CR, and 10-Hz rhythms are carried to common targets by the same postganglionic sympathetic neurons. Furthermore, we suggest that nonlinear interactions leading to the generation of new frequencies in SND may affect end-organ function beyond the level expected in simple cases of linear superposition of the primary rhythms. This suggestion is supported by our observation that strong coupling of the RR and CR rhythms resulted in appreciable power at the modulated frequencies.

Mobilization of peripheral blood progenitor cells by Betafectin PGG-Glucan alone and in combination with granulocyte colony-stimulating factor

Betafectin PGG-Glucan, a novel beta-(1,6) branched beta-(1,3) glucan purified from the cell walls of Saccharomyces cerevisiae, has been shown to synergize with myeloid growth factors in vitro and to enhance hematopoietic recovery in myelosuppressed mice and primates. Here we report that PGG-Glucan is also capable of mobilizing peripheral blood progenitor cells (PBPC). PGG-Glucan (0.5 mg/kg to 16 mg/kg) was administered intravenously to C3H/HeN male mice and blood collected at times ranging from 30 min to seven days after injection. Based on granulocyte-macrophage colony-forming cell (GM-CFC) levels, peak mobilization occurred 30 min after a 2 mg/kg PGG-Glucan dose. At this time GM-CFC numbers in PGG-Glucan-treated mice were approximately fourfold greater than in saline-treated control mice. A second, smaller wave of GM-CFC mobilization (approximately twofold increase) also occurred on days 4 and 5 after PGG-Glucan treatment. Mobilization was not associated with the induction of alpha-chemokines, which have recently been reported to induce rapid progenitor cell mobilization. Competitive repopulation experiments performed in irradiated female C3H/HeN mice revealed that, at three months after transplantation, more male DNA was present in bone marrow, splenic, and thymic tissues from animals transplanted with cells obtained from mice 30 min after a 2 mg/kg PGG-Glucan dose than in tissues from animals transplanted with cells obtained from saline-treated mice. Additional experiments evaluated the mobilization effects of PGG-Glucan (2 mg/kg) administered to mice which had been pretreated for three consecutive days with G-CSF (125 microg/kg/day). When blood was collected 30 min after PGG-Glucan treatment, the number of GM-CFC mobilized in combination-treated mice was additive between the number mobilized in mice treated with G-CSF alone and the number mobilized in mice treated with PGG-Glucan alone. These studies demonstrate that: A) PGG-Glucan can rapidly mobilize PBPC; B) the kinetic pattern of PGG-Glucan-induced mobilization is different from that of the CSFs; C) the reconstitutional potential of PGG-Glucan mobilized cells is greater than that of steady-state PBPC, and D) PGG-Glucan can enhance G-CSF-mediated PBPC mobilization.

Lymphohematopoietic engraftment in minimally myeloablated hosts

The concept that myeloablation to open space was a prerequisite for marrow stem cell engraftment has been challenged by studies showing high rates of engraftment in nonmyeloablated mice (Stewart et al, Blood 81:2566, 1993; Quesenberry et al, Blood Cells 20:97, 1994; Brecher et al, Blood Cells 5:237, 1979; Saxe et al, Exp Hematol 12:277, 1984; and Wu et al, Exp Hematol 21:251, 1993). However, relatively large numbers of marrow cells were necessary to achieve high long-term donor percentages. We have demonstrated, using a BALB/c male/female marrow transplant model and detecting male DNA in host tissues by Southern blot or fluorescent in situ hybridization, that exposure to doses of irradiation that cause minimal myeloablation (50 to 100 cGy) leads to very high levels of donor chimerism, such that relatively small numbers of marrow cells (10 to 40 million) can give donor chimerism in the 40% to 100% range. Studies of radiation sensitivity of long-term engrafting cells have shown that 100 cGy, although not myelotoxic, is stem cell toxic, and indicate that the final host:donor ratios are determined by competition between host and donor stem cells. These data indicate that low levels of irradiation should be an effective approach to nontoxic marrow transplantation in gene therapy or in attempts to create allochimerism to treat such diseases as cancer, sickle cell anemia, or thalassemia.

Osteogenesis of electrically stimulated bone cells mediated in part by calcium ions

Culture selected and expanded osteoblastic cells may be able to be reintroduced into massive skeletal defects to accelerate cell mediated regeneration of skeletal tissues, especially in bone ingrowth in total joint replacement, fracture healing, and osteoporosis. In vitro osteogenic cell culture is a useful model in studying the mechanism of bone metabolism under direct current stimulation. In this study, an osteoblastlike cell line was isolated from newborn rat calvaria. The osteogenic processes of the in vitro cultured cell line were studied by cytochemical, electron microscopic, and energy dispersive x-ray analysis techniques that resembled those observed in membrane bone ossification centers in vivo. Direct current stimulation of 100 microA/cm2 accelerated greatly the proliferation and calcification of the in vitro cultured cells. Intracellular free calcium ion metabolism was measured with an Adherent Cell Analysis and Sorting Machine. Under direct current stimulation, intracellular free calcium ion concentration increased an average of 2.3 times of the original level, which may play a key role in regulating osteogenesis and bone metabolism.

[The effect of the macrophages conditioned media(MOCM) on NGF secretion in newborn rat schwann cells in vitro]

OBJECTIVE

To study the influence of macrophages on nerve growth factor (NGF) secretion in newborn rat schwann cells.

METHODS

LPS-activated and not-activated adult rat peritoneal macrophages conditioned media (MOCM) were treated on purified cultured Schwann cells for 24, 48 and 72 hours in three different concentrations the NGF contents in the cultured Schwann cells suspension media were measured by a two-site enzyme-linked immunoserbent assay.

RESULTS

Both L-MOCM (LPS-activated MOCM) and N-MOCM(not-activated MOCM) obviously enhanced NGF secretion in chwann cells in each different concentration or testing time.

CONCLUSION

MOCM contains some factors which can promote NGF secretion in rat schwann cells in vitro, suggesting that macrophages regulating NGF secretion by secreted certain cytokines.

[A study on the relationship of primary hypertension in elderly and their quality of life in Changsha City]

To study the relationship between hypertension and their quality of life in Changsha City, in the elderly primary questionnaire concerning quality of life developed by the Chinese Geriatric Association was used to investigate 555 aged workers. A community-based control programme on hypertension and it's impact was analysed. The results of stepwise regression suggested that physical status and function of daily activities were both subjective and objective determinants of importance. Morbidity of hypertension was the highest among all chronic diseases influecing aged worker's health status. The total score of quality of life and activities in aged people with hypertension was obviously low. There were many problems in the community-based control program on hypertension in urban districts. The treatment on systolic hypertension has positive effect. Strenthening community-based control of hypertension has important impact on improving the quality of life among aged people.

Joint wavelet representation correlator for pattern recognition

A joint wavelet representation correlator is proposed as a newarchitecture to combine wavelets and the joint transformcorrelator. It performs wavelet representation preprocessing andthe correlation operation simultaneously. An intensity filter usedfor wavelet representation is the power spectrum of the waveletfunction and can easily be synthesized and displayed. Computersimulation shows that, as compared with previous joint wavelettransform correlators, its discrimination capability is better and itsperformance is more stable under input noise.

Paradoxical sympathetic nerve response to baroreceptor reflex activation

Spectral analysis revealed an enhancement of cardiac-related postganglionic sympathetic nerve discharge (SND) in response to elevated blood pressure in cats. Most of the enhancement occurred at blood-pressure levels above which coherence of SND to the arterial pulse at the frequency of the heart beat became maximal. This raises the possibility that the enhancement is due to mechanisms other than improved phase locking of SND to pulse-synchronous baroreceptor afferent nerve activity.

Chiaroscuro hematopoietic stem cell

These observations suggest several immediate clinical strategies. In gene therapy, approaches could be targeted to obtain cycling of hematopoietic stem cells and gene-carrying retrovirus vector integration followed by engraftment at an appropriate time interval which favors engraftment. The same type of approach can be utilized for stem cell expansion approaches. Alternatively marrow or peripheral stem cell engraftment can be obtained with minimal to no toxicity in allochimeric strategies in such diseases as sickle cell anemia or thalassemia. A similar approach could be useful in obtaining cell engraftment with minimal toxicity in therapies employing cellular immune (T-cell and NK-cell) attack against cancer. These areas of clinical application are outline in Table 3.

Adaptive smoothing respecting feature directions

Accurate extraction of the image feature directions is essential to image smoothing and other image processing tasks. We show that the gradient-based feature direction extraction method can be very erroneous. The gradient is too local, and it cannot detect oscillations. We have developed two new methods: the Hessian method, an approach using higher order differentiations, and the Gabor (1946) method, an approach using space-frequency analysis.

Nonlinear dynamics of the frequency locking of baroreceptor and sympathetic rhythms

We used phase plane analysis to identify modes of frequency locking of the 10-Hz rhythm in sympathetic nerve discharge (SND) to the cardiac cycle in urethan-anesthetized, baroreceptor-innervated cats. Frequency locking occurred in rational ratios predicted by a generic mathematical construct called the Farey tree. Both simple harmonic ratios (e.g., 1:3) and complex ratios (e.g., 2:5) comprised of relatively prime integers (no common divisor) were identified under natural conditions. Frequency locking in such ratios is attributed to forcing of the 10-Hz oscillator by pulse-synchronous baroreceptor afferent nerve activity (BNA). Ventricular pacing changed the frequency of the 10-Hz rhythm as well as heart rate so as to maintain or change the ratio of frequency locking in a predictable way. Intriguingly, frequency locking of the 10-Hz rhythm to medullary raphe sympathoinhibitory stimuli in simple harmonic ratios was accompanied by increased power in the 10-Hz band of SND, whereas locking in complex ratios led to decreased 10-Hz power. These findings raise the possibility that pulse-synchronous BNA also exerts divergent actions on the 10-Hz rhythm depending on the ratio of frequency locking. Augmented 10-Hz power can be attributed to the resonant properties of oscillators that are periodically forced at the same phase in their cycle.

Engraftment of hematopoietic stem cells in nonmyeloablated and myeloablated hosts

Hematopoietic stem cell engraftment has traditionally been assessed in irradiated murine hosts. More recently, we and others have shown that engraftment is virtually quantitative in host animals who have received no preconditioning myeloablation. It appears that at the stem cell level, engraftment may even be favored in the normal host. The final phenotypic readout in the engrafted animal is then determined by competition between the engrafted stem cells and the number of residual host stem cells. Further studies have indicated that with cytokine exposure in vitro, in vivo or 5-fluorouracil exposure and consequent stimulation of primitive hematopoietic stem cells to enter cell cycle, an engraftment defect relating to long-term engraftment occurs. This occurs in the face of an expansion of cycling surrogate stem cells as mirrored by the high proliferative potential colony-forming cell. These data indicate that the phenotype of the hematopoietic stem cell, as assessed in vitro, may not give insight into the phenotype of these cells in vivo.

[High performance liquid chromatographic determination of quercetin in the extract of Ginkgo biloba L. leaves]

This paper reports the HPLC determination of one of the flavones quercetin in the extract of Ginkgo biloba leaves. Quercetin was separated completely on an YWG-C18 column(0.46 cm x 15 cm), using a mixture of methanol, water and phosphoric acid(50:49.8:0.2) as mobile phase, with UV detection at 360 nm. The results have shown the recoveries to be between 95.3%-103.2% and RSD 1.86%.

Differential gender response produced by meal and ad lib feedings of a high-fat diet in Osborne-Mendel rats

We investigated if there were gender differences in metabolic consequences produced by meal feeding of a high-fat (HF) diet in male and female Osborne-Mendel rats. An HF diet was fed either ad lib (AL) or in 1 meal (MF) during the last 3 h of the dark cycle for 4 weeks (lights off from 2400 h to 1200 h). All rats were sacrificed at 1 of 3 time-points: prior to MF rats receiving their food at 0900 h, after food was taken from MF groups at 1200 h or 1500 h. Food intake, body weight, body fat weight, retroperitoneal adipose tissue lipoprotein lipase activity, plasma cholesterol, or HDL-cholesterol levels did not differ between MF- and AL-fed groups, but were higher in male than in female rats. There were no differences between the male and female groups in plasma levels of insulin and glucose or systolic blood pressures. Plasma triglyceride levels at 1200 h were significantly different between MF and AL Groups within either gender, but this was not observed at 0900 h or 1500 h. Body weights were correlated with internal fat weights and plasma cholesterol levels in both males (r = 0.57, p < 0.05) and females (r = 0.59, p < 0.05). Hence, it is the amount of HF diet ingested, rather than the pattern of meal feeding, that was the most significant factor related to gender differences in weight gain, increases in fat mass, and metabolic differences.

[A study on location of poles of terminal leads of ventricular fractionated potentials]

To eliminate the electromyogram-noise-signal from recording ventricular fractionated potentials (VFP) of the terminal leads(TLs), the multi-locations of leads were used to record ECG and VFP in 36 cases of controls and 68 cases of coronary heart disease. It was shown that the electromyogram-noise-signal could be minimized when TLs located separately at the point of infraclavicular cross lines axillaries media and the point of upperinguen cross lines axillaries media, and the essential formation of the ECG and VFP signals could not be changed except the QRS potentials becoming higher.

Coupled oscillators account for the slow rhythms in sympathetic nerve discharge and phrenic nerve activity

Phase-locked slow rhythms in sympathetic nerve discharge (SND) and phrenic nerve activity (PNA) are generally thought to arise from a common brain stem "cardiorespiratory" oscillator. The results obtained in vagotomized and baroreceptor-denervated cats anesthetized with pentobarbital sodium do not support this view. First, partial coherence analysis revealed that the discharges of pairs of sympathetic nerves remained correlated at the frequency of the central respiratory cycle after mathematical removal of the portion of these signals common to PNA. The residual coherence suggests that the slow rhythm in SND is dependent on central mechanisms in addition to those responsible for rhythmic PNA. Second, the rhythms in SND and PNA became coupled in a 2:1 relationship during either moderate systemic hypocapnia or hypercapnia. Third, the slow rhythm in SND was maintained when rhythmic PNA was eliminated during extreme hypocapnia. Fourth, during extreme hypercapnia, coherence of the rhythms in SND and PNA was drastically reduced. These results suggest that the slow rhythms in SND and PNA arise from separate oscillators that are normally coupled.

Binary joint transform correlator based on differential processing of the joint transform power spectrum

A novel binary joint transform correlator with differential processing in the joint transform power spectrum is proposed. The new model of the binary joint transform correlator can eliminate the dc component and sharpen the correlation intensity peaks, hence increasing its discrimination ability but with a lower complexity of computation. Preliminary results are shown by computer simulations.

Bispectral analysis of complex patterns of sympathetic nerve discharge

Bispectral analysis was used to demonstrate quadratic nonlinear coupling (i.e., phase locking) of different frequency components in inferior cardiac sympathetic nerve discharge (SND) of urethan-anesthetized rats. The complex patterns of SND analyzed included mixtures of 1) the cardiac-related and 10-Hz rhythms, 2) the 10-Hz rhythm and irregular 2-to 6-Hz oscillations, and 3) the 10-Hz rhythm and a lower frequency non-cardiac-related rhythm near 4 Hz. In some cases, the bicoherence function (normalized bispectrum) showed no phase locking of these frequency components. Cases of nil bicoherence are equated with linear superposition of frequency components, which implies the existence of multiple and noninteractive central circuits. Increased complexity of SND was observed in other cases, as evidenced by significant phase locking of different frequency components with or without frequency locking. Frequency locking (higher frequency rhythm is a multiple of lower) was confirmed by constructing Lissajous orbital plots showing covariation of voltages in selectively filtered bands of SND. We equate frequency locking with nonlinear coupling of the central generators of different sympathetic nerve rhythms and phase locking without frequency locking possibly with nonlinearities arising at levels below noncoupled central rhythm generators.

The solution structure of the Raf-1 cysteine-rich domain: a novel ras and phospholipid binding site

The Raf-1 protein kinase is the best-characterized downstream effector of activated Ras. Interaction with Ras leads to Raf-1 activation and results in transduction of cell growth and differentiation signals. The details of Raf-1 activation are unclear, but our characterization of a second Ras-binding site in the cysteine-rich domain (CRD) and the involvement of both Ras-binding sites in effective Raf-1-mediated transformation provides insight into the molecular aspects and consequences of Ras-Raf interactions. The Raf-1 CRD is a member of an emerging family of domains, many of which are found within signal transducing proteins. Several contain binding sites for diacylglycerol (or phorbol esters) and phosphatidylserine and are believed to play a role in membrane translocation and enzyme activation. The CRD from Raf-1 does not bind diacylglycerol but interacts with Ras and phosphatidylserine. To investigate the ligand-binding specificities associated with CRDs, we have determined the solution structure of the Raf-1 CRD using heteronuclear multidimensional NMR. We show that there are differences between this structure and the structures of two related domains from protein kinase C (PKC). The differences are confined to regions of the CRDs involved in binding phorbol ester in the PKC domains. Since phosphatidylserine is a common ligand, we expect its binding site to be located in regions where the structures of the Raf-1 and PKC domains are similar. The structure of the Raf-1 CRD represents an example of this family of domains that does not bind diacylglycerol and provides a framework for investigating its interactions with other molecules.

[Tuberculosis of the pancreatic head]

Eight patients with tuberculosis of the head of the pancreas were retrospectively reviewed. They were 4 men and 4 women (mean age 42.8 years). All patients complained of fever, sweating, fatigue, weight loss, and in the pain in the upper right belly. Abdominal mass was noted in 4 patients, jaundice in 3, and splenomegaly with hypersplenism in 4. Among the 8 patients, 5 suffered tuberculosis of the pancreas before the operation. All of them received laparotomy. Pancreatic tuberculosis in the all patients was confirmed by pathologically. Tuberculosis abscess was drained operatively. Antituberculosis therapy was available for all patients after the operation.

Comparison of results obtained with time- and frequency-domain analysis when searching for the 10-Hz rhythm in sympathetic nerve discharge

Kubota et al. (Neurosci. Lett., 196 (1995) 173-176) constructed distributions of the intervals between successive bursts of sympathetic nerve discharge (SND) in three mammalian species. The mode in such interburst interval histograms (IBIHs) was near 100 ms in most cases. This interval was equated with the 10-Hz rhythm in SND identified by others using power density autospectral analysis. However, in the current study we found a modal interval near 100 ms independent of whether the autospectrum showed a peak near 10 Hz. A 10-Hz rhythm appeared in the autospectrum of SND only when counts in the IBIH were normally distributed around 100 ms and the coefficient of variation was < 0.25. We conclude that a modal interval of 100 ms, by itself, is not a predictor of a 10-Hz rhythm in SND. As such, the conclusions of Kubota et al. on the spinal origin and ubiquity of the 10-Hz rhythm are open to question.

Increased coronary heart disease in Japanese-American men with mutation in the cholesteryl ester transfer protein gene despite increased HDL levels

Plasma high density lipoprotein (HDL) levels are strongly genetically determined and show a general inverse relationship with coronary heart disease (CHD). The cholesteryl ester transfer protein (CETP) mediates the transfer of cholesteryl esters from HDL to other lipoproteins and is a key participant in the reverse transport of cholesterol from the periphery to the liver. A high prevalence of two different CETP gene mutations (D442G, 5.1%; intron 14G:A, 0.5%), was found in 3,469 men of Japanese ancestry in the Honolulu Heart Program and mutations were associated with decreased CETP (-35%) and increased HDL chol levels (+10% for D442G). However, the overall prevalence of definite CHD was 21% in men with mutations and 16% in men without mutations. The relative risk (RR) of CHD was 1.43 in men with mutations (P < .05); after adjustment for CHD risk factors, the RR was 1.55 (P = .02); after additional adjustment for HDL levels, the RR was 1.68 (P = .008). Similar RR values were obtained for the D442G mutation alone. Increased CHD in men with mutations was primarily observed for HDL chol 41-60 mg/dl; for HDL chol > 60 mg/dl men with and without mutations had low CHD prevalence. Thus, genetic CETP deficiency appears to be an independent risk factor for CHD, primarily due to increased CHD prevalence in men with the D442G mutation and HDL cholesterol between 41 and 60 mg/dl. The findings suggest that both HDL concentration and the dynamics of cholesterol transport through HDL (i.e., reverse cholesterol transport) determine the anti-atherogenicity of the HDL fraction.

Frequency and effect of negative comments ("badmouthing") on medical students' career choices

BACKGROUND

Some call it "medical bigotry," and others describe it as the "hidden curriculum," but, by any name, the superficial and demeaning comments that students hear about particular career choices are thought to play a major role in discouraging the selection of primary care careers. This paper explores the frequency and effect of "badmouthing" on career choice with the hypothesis that it is more frequently heard about primary care disciplines but has relatively little influence on actual career choice.

METHOD

In 1993, 129 (79%) of the 163 University of Washington School of Medicine graduates responded to a two-page questionnaire about badmouthing. This information was used to refine the questionnaire. In 1994, 1,447 graduating students from nine medical schools were surveyed with the revised questionnaire. The schools were chosen to represent schools that had high, medium, and low proportions of students going into primary care careers.

RESULTS

A total of 1,114 questionnaires were returned, for a response rate of 77%. Badmouthing was heard frequently (76% of the responding students) and often occurred as early as the first and second years of medical school. The students heard badmouthing about their career choices most frequently when they selected surgery (91%) and family medicine (87%) and least frequently when they chose pediatrics (57%), p < .001. The students reported that the influence on career choice was low in general, but 186 students (17% of all respondents) did report altering their choices based on badmouthing.

CONCLUSION

Primary care fields and non-primary care fields were equally affected by career changes due to badmouthing. This study indicates that badmouthing, while pervasive across all disciplines and an unattractive aspect of the educational experience, cannot alone account for the low proportion of graduates choosing primary care careers.

[The role of amylase in abdominal fluid in evaluating severity of acute pancreatitis and its prognosis]

Acute pancreatitis (AP) was induced on 22 cats, by injecting the mixture of bile and trypsin at different doses into the main pancreatic duct (MPD). In Group A, 7 cats revealed pancreatic interstitial edema after the injection of the mixture at 0.8 mg/kg. In Group B, 8 cats received the injection of the MPD at 1.0 mg/kg which resulted in significant extensive necrosis of the pancreas. The same pathological change was found in Group C (7 cats), combined with lesions of the lung and the liver. The survival time was different, more than 7 days in Group A, 50.4 hours in Group B and 10.4 hours in Group C (P < 0.001). Amylase concentration also showed marked difference in different groups, 4,890 U/L in Group A; 13 952 U/L in Group B and 23,810 U/L (P < 0.001) in Group C. These results are directly proportional to the severity of AP, but inversely proportional to the survival time. It suggests that amylase concentration in abdominal fluid can be used as an important marker to evaluate the severity of AP and its prognosis.

Involvement of the switch 2 domain of Ras in its interaction with guanine nucleotide exchange factors

While Ras proteins are activated by stimulated GDP release, which enables acquisition of the active GTP-bound state, little is known about how guanine nucleotide exchange factors (GEFs) interact with Ras to promote this exchange reaction. Here we report that mutations within the switch 2 domain of Ras (residues 62-69) inhibit activation of Ras by the mammalian GEFs, Sos1, and GRF/CDC25Mm. While mutations in the 62-69 region blocked upstream activation of Ras, they did not disrupt Ras effector functions, including transcriptional activation and transformation of NIH 3T3 cells. Biochemical analysis indicated that the loss of GEF responsiveness of a Ras(69N) mutant was due to a loss of GEF binding, with no change in intrinsic nucleotide exchange activity. Furthermore, structural analysis of Ras(69N) using NMR spectroscopy indicated that mutation of residue 69 had a very localized effect on Ras structure that was limited to alpha-helix 2 of the switch 2 domain. Together, these results suggest that the switch 2 domain of Ras forms a direct interaction with GEFs.

Heligmosomoides polygyrus: resistance in inbred, outbred, and selected mice

Mice reared selectively as high- and low- immune responders to reinfection with Heligmosomoides polygyrus showed extremes of resistance and susceptibility after infection when compared to inbred BALB/C, DBA/I, CBA, and SJL/J and outbred Quackenbush (Q) mice. The levels of anti-H. polygyrus total IgG and IgG1, IgG2b, and IgG3 isotype antibodies detected in serum from the seven strains of mice after secondary and the eosinophil leucocyte counts in blood after both primary and secondary infections correlated positively and strongly with the levels of protective immunity developed when evaluated using a resistance index formulated from the infectivity, fecundity, and length of adult worms recovered after infection.

Characterization of the genomic structure of the mouse APLP1 gene

Amyloid beta protein (beta A4), the major component of the core of amyloid plaques in Alzheimer disease, is derived from the transmembrane amyloid precursor proteins (APPs). Our recent studies showed that a murine member of the evolutionarily conserved APP family, amyloid precursor-like protein 1 (APLP1), is specifically localized to the cerebral cortex postsynaptic density and may thus participate in brain synaptic function. To investigate regulatory mechanisms of APLP1 synthesis at the genomic level, we isolated and characterized genomic clones containing the mouse APLP1 gene. Sequence analysis revealed a genomic structure consisting of 17 exons and a promoter region that is devoid of apparent TATA and CCAAT boxes. The 5' region contains putative binding sites for AP-1, heat-shock protein, and Sp1, suggesting that multiple elements are potentially involved in regulating transcription of the APLP1 gene.