Nucleotide-dependent conformational change near the fulcrum region in Dictyostelium myosin II

In skeletal muscle myosin, the reactive thiols (SH1 and SH2) are close to a proposed fulcrum region that is thought to undergo a large conformational change. The reactive thiol region is thought to transmit the conformational changes induced by the actin-myosin-ATP interactions to the lever arm, which amplifies the power stroke. In skeletal muscle myosin, SH1 and SH2 can be chemically cross-linked in the presence of nucleotide, trapping the nucleotide in its pocket. Although the flexibility of the reactive thiol region has been well studied in skeletal muscle myosin, crystal structures of truncated nonmuscle myosin II from Dictyostelium in the presence of various ATP analogs do not show changes at the reactive thiol region that would be consistent with the SH1-SH2 cross-linking observed for muscle myosin. To examine the dynamics of the reactive thiol region in Dictyostelium myosin II, we have examined a modified myosin II that has cysteines at the muscle myosin SH1 and SH2 positions. This myosin is specifically cross-linked at SH1-SH2 by a chemical cross-linker in the presence of ADP, but not in its absence. Furthermore, the cross-linked species traps the nucleotide, as in the case of muscle myosin. Thus, the Dictyostelium myosin II shares the same dynamic behavior in the fulcrum region of the molecule as the skeletal muscle myosin. This result emphasizes the importance of nucleotide-dependent changes in this part of the molecule.

Methionine enkephalin immunoreactivity in the brain of the budgerigar (Melopsittacus undulatus): similarities and differences with respect to oscine songbirds

The brain of the budgerigar (Melopsittacus undulatus), a small parrot that acquires new vocalizations throughout life, was examined for immunoreactivity to the opioid peptide methionine enkephalin (mENK). mENK is a highly prominent feature of the chemical architecture of the forebrain vocal system of oscine songbirds. Forebrain vocal control nuclei are believed to have evolved independently in parrots and songbirds (Streidter [1994] J. Comp. Neurol. 343:35-56); however, recent studies have found similarities in the neural organization of vocal control pathways in budgerigars and songbirds (Durand et al. [1997] J. Comp. Neurol. 377:179-206). Among the similarities are the existence of recursive pathways interconnecting vocal control neurons in the archistriatum, basal ganglia (i.e., lobus parolfactorius), and dorsal thalamus. In the present study, we found that all vocal control nuclei within the budgerigar forebrain exhibit prominent mENK-like immunoreactivity (ELI) in fibers and somata. We also found striking similarities between the morphology of ELI elements in budgerigar vocal control nuclei and that described previously in songbird vocal nuclei. Despite these similarities, the budgerigar dorsal striatopallidum (lobus parolfactorius, paleostriatum augmentatum, and paleostriatum primitivum) and somatomotor (anterior) archistriatum exhibit unique patterns of ELI. The dorsal striatopallidum contained far less ELI, whereas the archistriatum contained far more than would be expected on the basis of previous studies of opioid peptides in other avian species, including pigeons, chickens, and songbirds. These differences may reflect neural specializations unique to the budgerigar that contribute to the extraordinary flexibility of the vocal motor system of this species to acquire socially significant stimuli throughout life.

[Clinical application of combined acupuncture-drug anesthesia in cerebral functional area operation]

OBJECTIVE

To reach for higher tumor resection rate and low incidence of disability by operation with combined acupuncture-drug anesthesia in cerebral functional area.

METHODS

According to the different operation ways, two groups of combination of body-acupuncture and ear-acupuncture were adopted.

RESULTS

Satisfactory effect was obtained in all the 80 patients, including 20 cases in language center and 60 in sensory and motor center. The anesthesia grade 1 rate was 100%. After operation, no aggravation in dysphasia or dysfunction was found, 5 cases showed aggravation on myasthenia and dysesthesia, but all recovered within 2-4 weeks.

CONCLUSION

Operation with combined acupuncture-drug anesthesia might result high tumor resection rate and low incidence of disability, therefore, this method of anesthesia could be regarded as one of the routine anesthesia methods.

[Maxillary expansion with magnetic force: an animal experimental study]

Two adult rhesus monkeys were chosen for the experimental study of maxillary expansion with magnetic force. The duration of experiment was 70 days. The following methods were applied: 1. measuring the width between the two canines and the width between the two first molars on the casts, 2. taking occlusal radiographs for the observation of premaxillary and midpalatal sutures. 3. observing the histological sections under the microscope. The results showed the width of 3 to 3 and the width of 6 to 6 significantly increased, associating with the adaptation of periodontal tissues to the action of magnetic force.

Matrix metalloproteinase inhibitors: a structure-activity study

Modifications around the dipeptide-mimetic core of a hydroxamic acid based matrix metalloproteinase inhibitor were studied. These variations incorporated a variety of natural, unnatural, and synthetic amino acids in addition to modifications of the P1' and P3' substituents. The results of this study indicate the following structural requirements: (1) Two key hydrogen bonds must be present between the enzyme and potent substrates. (2) Potent inhibitors must possess strong zinc-binding functionalities. (3) The potential importance of the hydrophobic group at position R3 as illustrated by its ability to impart greater relative potency against stromelysin when larger hydrophobic groups are used. (4) Requirements surrounding the nature of the amino acid appear to be more restrictive for stromelysin than for neutrophil collagenase, 72 kDa gelatinase, and 92 kDa gelatinase. These requirements may involve planar fused-ring aryl systems and possibly hydrogen-bonding capabilities.

Semiautomated segmentation of ovarian follicular ultrasound images using a knowledge-based algorithm

The application of a knowledge-based segmentation method to the problem of automatically detecting the outer follicle wall boundary in ultrasonographic images of ovaries is presented. A combination of computer detection and interactive adjustment was used to define an approximate inner follicle-wall boundary, which was then used by the computer algorithm as a priori knowledge to automatically find the outer follicle-wall border. The segmentation algorithm was tested on ultrasonographic images of women's ovaries that were imaged in vivo. The semiautomatic segmentations were compared to segmentations by an expert human observer in terms of border placement differences and in terms of quantitative parameters relevant to the physiologic status of the follicles. These physiological parameters include total and specific signal intensity from the follicle and from the follicle wall. The computer-detected outer follicle wall boundaries correlated well with the human observer-defined wall boundaries, in terms of enclosed follicle area, specific and total follicle signal, enclosed wall area, and specific and total wall signal. The actual border placement differences were also small, with a maximum placement difference of 1.47 +/- 0.83 mm and a root mean square (r.m.s.) placement difference of 0.59 +/- 0.28 mm.

[Studies of mechanism of erythrocyte deformability injury during hypobaric hypoxia in rats]

Rats were randomized into sea level group and hyoxic group. Erythrocyte filtration index (IF), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), erythrocyte [pH]i, [Mg2-]i, [Ca2+]i and [K+]i/[Na+]i were investigated in our studies. The results were as follows: 1. IF was increared in hypoxic group (0.234 +/- 0.060) 2. [Ca2+]i of hypoxic group (7.02 +/- 1.66) was evidently increased and correlated with its IF (r = 0.7386, P < 0.01), but [Mg2+]i had no obvious changes, [K+]i/ [Na+]i ratio of hypoxic group was reduced and negatively correlated with IF (r = -0.3957, P < 0.05), meanwhile, [pH] of hypoxic group increased evidently. 3. There was no statistic difference between MCHC of hypoxic and sea level group, but MCV of hypoxic group increased. These findings suggest that the changes of [Ca2+]i, [K+]i/[Na+]i ratio, [pH]i and MCV may play important role in erythrocyte deformability injury during hypoxia.

[The development of an Co-60 teletherapy missing tissue filling and compensating paraffin phantom and support]

The manufacturing way of missing tissue compensating paraffin phantom and the development of support are introduced in this article. They are designed to solve the problem that the dose is bad-distribated when the wedged plates are taken the places of tissue compensator in the course of missing tissue teletherapy. The manufacturing way of missing tissue compensating paraffin phantom is simple, Keeping paraffin phantom in position is accurate and the operating is simple and convenient.

[Preliminary study on the effects of Nd-Fe-B magnet on trace elements in rhesus monkeys]

Three adult rhesus monkeys were selected. Two of them were fixed with Nd-Fe-B magnets on the palates respectively. Nd-Fe-B magnet was not used in one monkey. Blood was drawn from all monkeys. Ten kinds of trace elements in blood were measured. The result showed that there was no quantitative difference in ten kinds of trace elements between the experimental and control animals.

[The relationship of the permeability coefficients of testosterone with solubility parameters of vehicles]

The effects of vehicles on the penetration through rat skin of testosterone were investigated. The solubilities of testosterone in various vehicles and the fluxes through rat abdomen skin had been determined. The solubility parameters of testosterone (delta i) and vehicles (delta v(n)) were calculated by Hildebrand's method. There was a good inverse parabola correlation between the log permeability coefficients (logp) and (delta v(n)). When delta v(n) approched delta i the permeability coefficients of testosterone approched the minimum as its limit.

Antisense inhibition of silica-induced tumor necrosis factor in alveolar macrophages

Tumor necrosis factor-alpha (TNFalpha) has been shown to play an important role in the pathogenesis of silicotic fibrosis. In this study, antisense oligonucleotides targeted to TNFalpha mRNA were used to inhibit silica-induced TNFalpha gene expression in alveolar macrophages. To achieve macrophage-specific oligonucleotide delivery, a molecular conjugate consisting of mannosylated polylysine that exploits endocytosis via the macrophage mannose receptor was used. Complexes were formed between the mannosylated polylysine and oligonucleotides and added to the cells in the presence of silica. Enzyme-linked immunoadsorbent assay showed that the complex consisting of the conjugate and antisense oligomer effectively inhibited TNFalpha production, whereas the oligomer alone had much less effect. Reverse transcriptase-polymerase chain reaction analysis revealed that the reduction in TNFalpha secretion was associated with specific ablation of targeted TNFalpha mRNA. The conjugate alone or conjugate complexed with inverted or sense sequence oligonucleotide had no effect. The promoting effect of the conjugate on antisense activity was shown to be due to enhanced cellular uptake of the oligomer via mannose receptor-mediated endocytosis. Cells lacking mannose receptors showed no susceptibility to the conjugate treatment. These results indicate that effective and selective inhibition of macrophage TNFalpha expression can be achieved using the antisense mannosylated polylysine system.

Environmental and occupational determinants of blood pressure in rural communities in China

PURPOSE

To identify and characterize major environmental and occupational determinants of blood pressure in rural communities in China.

METHODS

In 1993 we conducted a large cross-sectional, community-based study of 20,216 residents aged 15 years or older, from the Yijing area of Anhui Province (8022 men, 12,194 women), one of whom were receiving treatment for hypertension. The mean systolic blood pressure was 116.7 +/- 19.5 mmHg for men and 113.2 +/- 19.4 mmHg for women.

RESULTS

The mean diastolic blood pressure was 72.4 +/- 12.1 mmHg for men and 70.4 +/- 11.6 mmHg for women. Age and body mass index were the two most important determinants of blood pressure in this population. With controls for age and body mass index, height and weight remained significant predictors of blood pressure. Multiple linear regression analysis indicated that alcohol consumption, self-reported exposure to noise, drinking of tap water and pond water, occupational exposure to dust/fumes/gases, rice consumption, inferior housing, household crowdedness, and being unmarried were related to increased blood pressure levels. Vegetable intake, frequent consumption of meat at meals, high level of physical activity, exposure to straw-combustion smoke, and pesticide use were negatively associated with blood pressure.

CONCLUSIONS

Our study demonstrated that a broad array of demographic, ergonomic, nutritional, and environmental factors are critical determinants of blood pressure in this rural Chinese population.

X-Ray Focusing Optics and Its Applications in XRMF and XRL

A brief review of the research on capillary x-ray focusing optics (the x-ray lens) at the X-Ray Optics Laboratory of the Institute of Low Energy Nuclear Physics at Beijing Normal University is presented. As a new tool for controlling powerful wide-bandwidth x-ray beams, the x-ray lens has very broad applications in both pure and applied sciences and in industry. Research toward developing such optics continues to grow in Russia, United States, and China. Some applications of x-ray lenses have also been developed. The preliminary results of theoretical and experimental studies on applications of x-ray lenses in x-ray microfluorescence and deep submicron lithography are quite encouraging. These achievements anticipate the appearance of a new generation of x-ray equipment.

[On the effect of Chinese lacquer upon the cell division of root tip of Allium cepa]

Chinese Lacquer, as a fine coating, has been studied and applied for thousands years. The allergic reaction in Chinese Lacquer on the human skin has also been known early. The reaction of Chinese Lacquer on mitosis of cell in plant meristem have not been reported yet and was carefully studied in this paper. The result showed that Chinese Lacquer induced severe abnormality of mitotic division in Allium cepa root tips. This was more obvious in the anaphase and telophase, especially in the former phase laggard chromosomes, chromosome bridges, acentric fragments and polypolar distribution could be seen frequently. A lot of polynuclear bodies were observed in the telophase. Therefore, we think that the Chinese Lacquer can be used as a plant cell mutagen, and suggest geneticists and physiologists to do more researches on the effects of Chinese Lacquer at the genetic variation, metabolism etc.

Electronic Band Structure and Madelung Potential Study of the Nickelates La(2)NiO(4), La(3)Ni(2)O(7), and La(4)Ni(3)O(10)

Tight-binding electronic band structures and Madelung potentials were calculated for La(2)NiO(4), La(3)Ni(2)O(7), and La(4)Ni(3)O(10) to examine why a metal-to-metal transition occurs in the nickelate Ln(4)Ni(3)O(10) (Ln = La, Nd, Pr). La(4)Ni(3)O(10) and La(3)Ni(2)O(7) are each found to have two hidden one-dimensional (1D) Fermi surfaces, which suggests that both compounds should possess a charge density wave instability. Factors leading to hidden 1D Fermi surfaces in the e(g) block bands of the nickelates were discussed.

Occupational and Environmental Risk Factors for Asthma in Rural Communities in China

Respiratory allergens such as dust, gases/fumes, and hay smoke, which are frequently present in agricultural settings, can cause or aggravate asthma. The purpose of this study was to examine the relationships between occupational and environmental exposures and asthma in Chinese rural communities. The study population consisted of 28,946 people 15 years old or older, living in rural areas of Anhui province, China. A modified Mandarin translation of the ATS-DLD questionnaire was administered by trained interviewers to request information about exposures to specific occupational/environmental agents and respiratory disorders. In Huaining, the prevalence of wheezing was 3.8% for men; 2.1% for women; the prevalence of asthma was 1.6% for men; 1.8% for women. In Zongyang, the prevalence of wheezing was 2.7% for men; 1.9% for women; the prevalence of asthma was 1.7% for men; 1.2% for women. With control for potential confounders such as gender, age, residential area, education level, and smoking status, the pooled adjusted odds ratios (ORs) of wheezing and asthma for the group exposed to wood/hay smoke were 1.36 (95% CI: 1.14-1.61) and 1.27 (95% CI: 1.02-1.58), respectively. For coal-stove users, the pooled adjusted ORs were 1.47 (95% CI: 1.09-1.98) for wheezing and 1.51 (95% CI: 1.05-2.17) for asthma. After stratification of the subjects by dust type, the estimated ORs for wheezing were 1.58 (95% CI: 1.02-2.44) among the group exposed to inorganic dust and 3.03 (95% CI: 1.25-7.33) among the group exposed to metal dust. Asthma was not shown to be significantly associated with any specific dust type. Findings of the present study are consistent with previously reported adverse respiratory health effects related to occupational/environmental exposures to wood/hay smoke and dust, and indicate the need for further occupational disease surveillance in rural communities.

[A comparison of the modified gamma nail and the ender nail for treatment of intertrochanteric fractures]

We made a comparison between the modified Gamma nailing and the Ender nailing in the treatment of 102 patients with intertrochanteric fracture. Sixty patients were treated with the modified Gamma nailing and forty-two patients with the Ender method. The preoperative conditions of the patients in the two groups were similar as showed by statistical analysis. More intraoperative bleeding was recorded in the modified Gamma nail group. However, there were a earlier full weight -bearing, a better hip function and a lower rate of operative complication in the patients treated with the modified Gamma nailing. We conclude that with the modified technique and the modified femoral component the Gamma nail is advanced in the treatment of intertrochanteric fracture. However, it is danger to apply in elderly patients accompanied with certain vital problems. For these patients the Ender nail may be considered.

Oxidation states of the manganese cluster during the flash-induced S-state cycle of the photosynthetic oxygen-evolving complex

The Mn K-edge x-ray absorption spectra for the pure S states of the tetranuclear Mn cluster of the oxygen-evolving complex of photosystem II during flash-induced S-state cycling have been determined. The relative S-state populations in samples given 0, 1, 2, 3, 4, or 5 flashes were determined from fitting the flash-induced electron paramagnetic resonance (EPR) multiline signal oscillation pattern to the Kok model. The edge spectra of samples given 0, 1, 2, or 3 flashes were combined with EPR information to calculate the pure S-state edge spectra. The edge positions (defined as the zero-crossing of the second derivatives) are 6550.1, 6551.7, 6553.5, and 6553.8 eV for S0, S1, S2, and S3, respectively. In addition to the shift in edge position, the S0--> S1 and S1--> S2 transitions are accompanied by characteristic changes in the shape of the edge, both indicative of Mn oxidation. The edge position shifts very little (0.3 eV) for the S2--> S3 transition, and the edge shape shows only subtle changes. We conclude that probably no direct Mn oxidation is involved in this transition. The proposed Mn oxidation state assignments are as follows: S0 (II, III, IV, IV) or (III, III, III, IV), S1 (III, III, IV, IV), S2 (III, IV, IV, IV), S3 (III, IV, IV, IV).

Comparison of stored and secreted rat pancreatic digestive enzymes by mass spectrometry: alpha-amylase

As part of a continuing effort to better understand the mechanisms of protein secretion, we compared the mass of pancreatic digestive enzymes, in resting and stimulated states, both in secretion and in the zymogen granule to determine whether their secretion is accompanied by chemical modification. Mass spectra were obtained applying the electrospray method on samples separated by reverse-phase HPLC. We report here our results for alpha-amylase (1,4-alpha-D-glucan glucanohydrolase EC 3.2.1.1). The data illustrate structural differences between states and compartments for this enzyme. Multiple isozymes were identified from the mass spectra, varying roughly from 52 to 60 kDa. On the basis of mass comparisons, not all of the products seen in the zymogen granule were found in secretion, nor were all secreted isoforms in the granule. Stimulation of protein secretion with a cholinergic agonist, led to time-dependent changes in the number and masses of isoforms in secretion, leaving only one of five resolvable forms in the granule. Only one form, 55.5 kDa, was found in all samples, granule and secretion. In addition to these differences, microheterogeneities of 400 Da or less were observed. The data suggest the differential or non-parallel release of different amylase forms and their chemical modification during the secretion process. As such, release appears to involve a third, intermediate compartment, between zymogen granule to ductal space, such as the cytoplasm, in which chemical modification takes place.

Enhanced cellular uptake of oligonucleotides by EGF receptor-mediated endocytosis in A549 cells

PURPOSE

The goal of this study was to investigate the feasibility of utilizing epidermal growth factor (EGF) receptor-mediated endocytosis to enhance cellular uptake and targeting of oligonucleotides in epithelial cancer cells. To overcome the problem of endosomal entrappment associated with receptor-mediated delivery, we also examined the effects of two fusogenic peptides, polymyxin B and influenza HA2 peptide, for their capability to promote cytoplasmic delivery of oligonucleotides.

METHODS

A molecular conjugate consisting of EGF and poly-L-lysine (PL) was synthesized and complexed with 5' fluorescently-labeled oligonucleotide. Cellular uptake of the complex in presence or absence of the fusogenic peptides was monitored fluorometrically. Microscopic studies were performed to visualize the intracellular distribution of the oligonucleotide.

RESULTS

Cells treated with the complex exhibited intracellular fluorescence intensity significantly enhanced over free oligonucleotide-treated controls. The uptake of the complex was shown to occur via the EGF receptor-mediated pathway. Fluorescence microscopic studies revealed cellular internalization of the complex, however, the complex appeared to be accumulated in endocytic vesicles. Exposure of the cells to complex in presence of HA2 peptide and polymyxin B resulted in a more diffused intracellular fluorescence pattern and a corresponding increase in fluorescence intensity. These results are consistent with the known fusion and destabilizing activities of the peptides.

CONCLUSIONS

Since EGF receptors are overexpressed in many cancer cell types, the EGF-PL conjugate may potentially be used as an effective and selective delivery system to enhance uptake of oligonucleotides into cancer cells.

An enzyme-linked immunosorbent assay using biotinylated heparan sulfate to evaluate the interactions of heparin-like molecules and basic fibroblast growth factor

Basic fibroblast growth factor (bFGF) is a member of the heparin-binding growth factor family that interacts with cell surface heparan sulfate (HS) proteoglycans and extracellular matrix heparin. Here we report the development of a simple and sensitive assay that used biotinylated HS or heparin to bind to bFGF coated onto 96-well microtiter plates. Bound labeled HS or heparin was reacted with enzyme-linked streptavidin and results were recorded as optical density. Increased molar excess of biotin resulted in increased incorporation of biotin and higher signal without compromising binding. Glycosaminoglycans and modified heparins were assayed for their ability to compete with biotinylated HS for binding to bFGF. Inhibition of that binding by heparin and HS but not by chondroitin sulfate A or C, dermatan sulfate, or keratan sulfate demonstrated the specificity of the glycosaminoglycan binding. Structural modifications of heparin produced various degrees of inhibition with high structural specificity. Although removal of N-sulfates or 2,3-O-sulfate groups resulted in significant loss of inhibition, removal of 6-O-sulfates had little affect on binding. Carboxyl reduction or N-acetylation following N-desulfation produced heparinoids with moderate changes in binding capacity. Results from this assay are in agreement with previous data from our laboratory and reports from other researchers with respect to the specificity of glycosaminoglycan binding to bFGF and the role of 2,3-O- and 6-O-sulfate groups of heparin. The flexibility of this assay, in both the amount of label incorporated and the variability of solid substrate, makes this an excellent tool to study other heparin binding proteins.