Study on the pathogenic factors of Kashin-Beck disease

Kashin-Beck disease (KBD) is a chronic osteoarthritic disease, endemic in parts of China. Its etiology is unknown. Selenium deficiency, high concentration of organic matter (mainly fulvic acid) in drinking water, and severe contamination of grain by fungi have been proposed environmental causes. Free radicals, possible mediators between the environmental factors and origin of KBD, have been studied in this work. Drinking water from KBD-affected areas contains a higher level of semiquinone radicals than that from disease-free areas. In animal experiments, fulvic acid (FA) accumulated in the skeletal system as semiquinone radicals. Contamination of grain by Fusarium oxysporum or Alternaria alternata significantly increased the content of semiquinone radicals. Furthermore, corn grown in endemic areas had a higher content of radicals than that from disease-free areas. The g factor values for these radicals from contaminated corn were about 2.0040, in the range of semiquinone radical. In monolayer culture of human embryonic chondrocytes, FA and aqueous extracts of grain contaminated by Fusarium injured the chondrocytes and enhanced lipid peroxidation. Selenite and superoxide dismutase (SOD) protected the cells from injury by these toxins and reduced lipid peroxide. Lower glutathione peroxidase activities and higher levels of lipid peroxidation were also found in the children living in KBD-affected regions. Thus, FA and the mycotoxin, which are seen as exogenous free-radical carriers, are important environmental factors in the pathogenesis of Kashin-Beck disease; and selenium, vitamin C, and vitamin E, which inhibit free-radical formation, are considered to be protective.

Effects of p-chlorophenylalanine on thermoregulation and sleep in rats

Sleep/waking and body temperature (Tb) were recorded in male rats in a 12:12 light-dark photoperiod at one of 3 ambient temperatures (Ta's): 20, 30, or 32 degrees C. After adaptation to the sleep recording chamber for at least 48 h, the rats were injected with saline at the beginning of lights-on (day S1). Twenty-four hours later (day P1), they were injected with PCPA (300 mg/kg, i.p.) and recordings continued for 4 more days (P2-P5). At these Ta's, hypothalamic 5-HT was depleted by 66-75% 30 h post-PCPA. Changes in both amplitude and acrophase of Tb depended on Ta. Compared to S1, amplitude was reduced on P2-P4 at 20 degrees C and on P3-P4 at 30 degrees C. Acrophase was advanced on P1-P3 at Ta 20 degrees C only. Sleep variables were generally independent of Ta and largely unchanged in the dark. In the light, amounts of slow-wave sleep (SWS) were depressed on P2-P4, number of bouts decreased on P3-P5 and percent nocturnality decreased on P2-P5. Bout length was depressed on P2 and lengthened on P4-P5. Acrophase was delayed on P2-P4 at Ta 30 degrees C. Amounts of rapid-eye-movement sleep (REMS) were depressed on P1-P3. REMS bout length decreased on P1-P3. The decreases in number of REMS bouts seen on P1-P3 depended on Ta. Changes in percent nocturnality and acrophase of REMS were minor. Waking----SWS transitions decreased on P3-P5 while SWS----REMS transitions were reduced on P1-P2. These results suggest that PCPA affects circadian aspects of both Tb and sleep, that 5-HT is important in the initiation of SWS bouts, and finally that the mechanisms by which 5-HT depletion affects Tb, SWS and REMS are different.

Effect of chronic administration of dexfenfluramine on blood pressure in salt-sensitive rats

Chronic administration of dexfenfluramine, at a relatively low daily dose, slowed the development of salt-induced elevation of blood pressure in salt-sensitive (Dahl DS and Rapp SS) rats. This effect could not be accounted for by drug-related anorexia alone. Elevated serotonin activity, possibly in the brain, may underlie this antihypertensive action of dexfenfluramine.

An optical biosensor for lysine based on the use of lysine decarboxylase and a cadaverine-sensitive membrane

We describe an optical biosensor for lysine based on the use of lysine decarboxylase and an optical transducer for detection of cadaverine which is formed as a result of enzymatic action. A plasticized PVC (polyvinyl chloride) membrane containing a lipophilic tartrate as the amine carrier acts as the optical cadaverine sensor. The transport of the cadaverine cation into the membrane is coupled to a transport of a proton (of the indicator dye) out of the membrane. This causes a spectral change of the indicator dye which can be related to the cadaverine concentration, provided the pH is kept constant. The enzymatic reaction is performed in an enzyme reactor which is part of a flow-through system. The dynamic range is from 0.1 to 100 mM for both cadaverine and lysine. While the cadaverine sensor is moderately selective (ethylamines, for example, interfere), the whole sensor system is highly specific for lysine, nicotine being the only major interferent. Unlike other enzyme-based detection schemes where the production of CO2 (in case of decarboxylases) or consumption of oxygen (in case of oxidases) is measured, this scheme is based on the measurement of the organic ammonium ion (cadaverin cation) formed in the enzymatic reaction. The major advantage of this approach is that in many real samples there is a rather low and fairly constant background of organic amines.(ABSTRACT TRUNCATED AT 250 WORDS)

[Preliminary studies on subtypes of respiratory syncytial virus in China]

An analysis of subtypes of 9 respiratory syncytial (RS) viruses isolated from Guangzhou and Nanjing areas of china was carried out with eight Sweden RS-subtype specific monoclonal antibodies (MAbs) and 7 internal anti-RS MAbs. All these MAbs directed against respectively the large Glycoprotein (G), fusion protein (F), nucleoprotein (NP), and phosphoprotein (P) components of the prototype Long strain of RS virus. The patterns of the reactions of these MAbs to the nine isolated strains of RS virus were compared with indirect immunofluorescence assay (IFA), alkaline phosphoesterase-anti alkaline phosphoesterase (APAAP) enzyme-linked assay and Western blotting. The antigenic variations were founded among the strains of RS virus, and two subtypes allocated to the subtype A and B of RS virus by using the eight RS-subtype specific MAbs. Seven out of the 9 isolated strains of RS virus belonged to the subtype A, and two were being to the subtype B. The antigenic diversities were also founded within the same subtype, and the main pronounced difference were observed on the G glycoprotein by using the internal anti-RS MAbs. These findings are potentially important both for vaccine development and for the understanding of clinical and epidemiological characteristics of RS virus.

Blockade of the AMPA receptor prevents CA1 hippocampal injury following severe but transient forebrain ischemia in adult rats

The cytoprotective effect of NBQX, a selective AMPA receptor antagonist, was tested following 10 min of severe forebrain ischemia using the 4-vessel occlusion model. Immediately, and at 15 and 30 min following reperfusion, adult Wistar rats received intraperitoneal injections of either saline (n = 5), 1 mg lithium chloride (n = 17) or 30 mg/kg of the lithium salt of NBQX (n = 18). In saline-treated animals 82 +/- 12% of CA1 hippocampal neurons were lost. Of those treated with lithium 70 +/- 23% were injured, while those given NBQX sustained only 40 +/- 34% CA1 necrosis (P less than 0.01). Twelve of 18 NBQX-treated animals had less than 30% CA1 injury as compared with 1 of 17 lithium-treated animals. The AMPA receptor may play a more important role than the NMDA receptor in selective ischemic necrosis of hippocampal neurons.

Arginine/serine-rich domains of the su(wa) and tra RNA processing regulators target proteins to a subnuclear compartment implicated in splicing

Two unrelated pre-mRNA splicing regulators-suppressor-of-white-apricot (su(wa)) and transformer (tra)-contain distinctive, approximately 120 amino acid arginine/serine (RS)-rich domains. Deletion of the su(wa) RS domain eliminates function. Replacement with the tra RS domain restores su(wa) function to nearly wild-type levels. Replacement with a 10 amino acid simple nuclear entry signal allows partial, inefficient function. Thus, the su(wa) RS domain apparently serves a generic function(s) subsuming nuclear entry. Moreover, immunocytochemical studies demonstrate that both RS domains specifically direct localization of a fused reporter protein to a punctate subnuclear compartment shown previously to be enriched in several constitutive splicing components. We propose that RS domains are a new class of targeting signals directing concentration of proteins in a subnuclear compartment implicated in splicing metabolism.

Synthesis, isolation, and characterization of endogenous beta-galactoside-binding lectins in human leukocytes

Galaptin, a beta-galactoside-binding lectin, was isolated from human buffy coat cells (peripheral leukocytes) and spleen by affinity chromatography. The molecular weight (32K) of the native buffy coat galaptin was similar to that for splenic galaptin. Their subunit molecular weight (14.5K), pI (4.60-4.85), and amino acid composition were identical. Both galaptins showed the presence of a single polypeptide when subjected to reversed-phase HPLC. Monospecific rabbit polyclonal antiserum raised against the 14.5-kDa subunit of splenic galaptin reacted with a 14.5-kDa polypeptide present in buffy coat cells, Epstein-Barr virus-immortalized B lymphoblastoid cells, and HL-60 promyelocytic leukemia cells. However, galaptin was not synthesized in vitro by buffy coat cells. Rather, a monomeric beta-galactoside-binding protein of Mr 15.5-16.5K that is immunologically distinct from galaptin was synthesized. This galactoside-binding protein was separable from galaptin by polyacrylamide gel electrophoresis and by anion-exchange chromatography. In contrast, immunoprecipitation experiments confirmed that galaptin was synthesized by the B lymphoblastoid cells. cDNA corresponding to the B lymphoblastoid cell mRNA encoding galaptin was amplified by the polymerase chain reaction. The amplified product was partially sequenced, and 299 nucleotides were identified. The derived amino acids corresponded to residues 6-65, 84-114, and 118-126 found to be present in human splenic galaptin. Immunohistochemical analyses revealed that galaptin was distributed throughout the cytoplasm of B lymphoblastoid cells rather than being localized to the cell surface.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pharmacological studies on the Chinese drug radix Angelicae dahuricae]

Several species of the Chinese drug Angelica dahurica from different habitats have been studied in terms of anti-inflammatory, analgesic and antipyretic actions and acute toxicity. The medical value of these species is reported in this paper as a guideline for their clinic application.

Effect of arginine on immune function in rats with obstructive jaundice

In this study we used an experimental model produced by bile duct ligation (BDL) in rats to demonstrate relation between immune function and susceptibility to infection associated with obstructive jaundice and immunoregulatory effect of arginine in BDL rats. Our experimental results showed that thymus weight, content of lymphocytes in thymus and responsiveness to Con A in vitro were dramatically reduced in BDL rats as compared to rats with sham operation and that the impairment of lymphocyte function was significantly related to the susceptibility to infection. Arginine, as a T cell stimulator, markedly improved immune function and decreased susceptibility to infection of BDL rats.

Cytogenetic analysis of hepatic cell lines derived from SV40-T antigen gene-harboring transgenic mice

A total of five hepatic cell lines were established from SV40-T transgenic mice at different stages of development. Karyotype analysis performed on these cell lines revealed 1) chromosomal instability manifested by numerous karyotypic alterations, 2) non-random numerical changes of chromosome number 18 and 3) frequent occurrence of marker chromosomes in four of the five lines. These findings indicate that genetic abnormalities occur very frequently in hepatocytes of the transgenic mice, most probably caused by the mutagenic action of T-antigen, raising the possibility that they play essential roles in initiation and progression in this model of murine hepatocarcinogenesis.

Vitreous replacement by gas as a therapeutic modality in bacterial endophthalmitis

We investigated vitreous replacement by long-lasting gas in the management of severe Staphylococcus aureus endophthalmitis in 19 rabbits randomized for vitrectomy (9 animals) and for vitrectomy followed by replacement of the vitreous by a 20% perfluoropropane-80% air mixture (10 animals). Both groups received systemic antibiotics and achieved comparable intraocular antibiotic levels. Clinically and histopathologically, gas-filled eyes demonstrated less inflammation than did eyes without gas (P less than 0.01). Replacement of vitreous by gas offers an effective adjunct to vitrectomy by eliminating a culture medium, preventing vitreous abscess formation, enabling fundus visualization, and delaying the onset of retinal detachment.

Analysis of bovine herpesvirus 4 (DN 599) major antigens with monoclonal antibodies and polyclonal immune serum

Monoclonal antibodies (MAbs) and polyclonal immune sera were produced and used to identify the major antigens of bovine herpesvirus type 4 (BHV-4). SDS-polyacrylamide gel electrophoresis of immunoprecipitates of radiolabeled lysates from infected cells resolved 24 peptide bands varying from 12 kDa to over 300 kDa. Six peptides were identified as major viral antigens by immunoprecipitation. Based on the pattern of radioimmunoprecipitation, MAbs were assigned into four groups. Group 1 precipitated a tunicamycin-sensitive glycoprotein complex which contained six components (245, 190, 152, 123, and 48/46 kDa). Deglycosylation with endoglycosidase F revealed two peptides with Mr of 93 and 38 kDa as the basic peptides of the glycoprotein complex. In addition, a 115 kDa glycopeptide containing glycan-peptide bonds of mixed type was identified. Group 2 precipitated a non-glycosylated protein complex consisting of three monomers (33/31/30 kDa). Groups 3 and 4 reacted with single monomeric non-glycosylated peptides with Mr of 48 and 14 kDa, respectively. Although none of the MAbs exhibited significant neutralizing activity, some reacted strongly in immunosorbent and/or immunohistochemical assays, suggesting they may be good candidates for use in diagnostic assays.

Altered lymphocyte subsets and natural killer cells of patients with obstructive jaundice in perioperative period

Sepsis is a common and occasionally lethal complication of obstructive jaundice. The reasons for the increased susceptibility to infection are not fully understood. This study was conducted to examine lymphocyte subsets and natural killer cells of patients with obstructive jaundice in perioperative period. In these patients, when compared with normal controls, there was a significant reduction in the percentage of Leu 4 (pan T lymphocytes), Leu 3a (T helper cells) and Leu 7 (natural killer cells) before operation, and the immune suppression induced by surgical operation was more marked and persistent.

[Relationship between free radicals and diabetic microangiopathy]

Lipid peroxide (LPO) values in blood plasma, along with the glutathione peroxidase (GSH-PX) activity in whole blood and superoxide dismutase (SOD) activity in erythrocytes were determined in 50 patients with non-insulin-dependent diabetes mellitus (NIDDM) and in 33 control subjects. The mean LPO value, SOD activity, LPO/GSH-PX and LPO/SOD ratios in the diabetic patients were significantly higher than those in the control subjects. The increases of LPO value, LPO/GSH-PX and LPO/SOD ratios were more pronounced in diabetics with microangiopathy than in those without microangiopathy. Our results suggest that free radicals may be implicated in the pathogenesis of diabetic microangiopathy.

[Percutaneous mitral commissurotomy by a domestic balloon catheter in 215 patients and a follow-up study of 41 cases]

Between June, 1987 and June 1990, percutaneous balloon catheter mitral commissurotomy (PBMC) was performed in 215 patients (mean age 37.1 +/- 10.1 years) with rheumatic mitral stenosis by domestic balloon catheter and were successful in 213 patients (99%). After PBMC, there was a significant improvement in mitral gradient (2.58 +/- 0.93 kPa to 0.66 +/- 0.31 kPa, P less than 0.001), mean left atrial pressure (3.18 +/- 0.94 kPa to 1.26 +/- 0.55 kPa, P less than 0.001), mitral valve area (1.14 +/- 0.22 cm2 to 2.27 +/- 0.42 cm2, P less than 0.001) and left atrial dimension (46 +/- 5 mm to 36 +/- 4 mm, P less than 0.001). Severe mitral regurgitation was noted in two patients (0.9%) and pericardial tamponade in one patient (0.5%). No death was occurred. 41 patients from the first 160 ones were followed up for a mean of 25 +/- 6 months (12-36 months). Mitral valve area remained stable in all but one with restenosis. In addition, the experience on prevention and cure for complications of PBMC were discussed.

[Characteristics of central acute resetting of high threshold baroreflex in rabbit's aortic nerves]

Experiments were performed on 37 urethane-anesthetized rabbits. The aortic nerves, carotid sinus nerves and vagus nerves were cut, MAP and renal sympathetic nerve activity (RSNA) were recorded. The conditional stimulation CSc (0.5 ms, 10 Hz, 4-6V, 5 min) was used to mimic the information of baroreflex non-medullated afferent fibers responding to acute increase of BP. Test stimulation TSa (0.02 ms, 0-80 Hz/30 s, 4-6V) and TSc (0.5 ms, 0-20 Hz/30s, 4-6V) was used to examine the responses of baroreflex A- and C-fibers. After CSc at 1 min the reflex MAP and RSNA of TSc was attenuated at 45.5% (P less than 0.01) and 10.6% (P less than 0.05), the MAP response of TSa was attenuated at 32.1% (P less than 0.05), but the RSNA response was not. From the further investigation it is concluded that the characteristics of central acute resetting are dependent on the components of baroreflex afferent fibers. The reflex responses are attenuated mainly by correspondent afferent components.

Differential regulation by 1,25-dihydroxyvitamin D3 of calbindin-D9k and calbindin-D28k gene expression in mouse kidney

The mouse kidney is a unique tissue since both vitamin D-dependent calcium binding proteins (calbindin-D9k and calbindin-D28k) are present in the same cells of the distal convoluted tubule. We have used specific complementary DNAs to mouse calbindin-D9k and mouse calbindin-D28k and Northern and slot blot analyses in order to obtain a better understanding of the regulation of two different molecular expressions of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] action in the same cells. Both calbindins were found to be regulated developmentally in a similar manner (an increase in gene expression between birth and 1 week of age, coinciding with nephron differentiation, and a peak at 3 weeks of age). However, the time course of response of the messenger RNA of each calbindin to 1,25(OH)2D3 was markedly different. The peak of induction of renal calbindin-D28k mRNA was at 12 h after a single injection of 1,25(OH)2D3 (200 ng/100 g body wt) to vitamin D-deficient mice, and a decrease was observed at 24 h (similar to the time course of response of other steroid-regulated genes). Interestingly, unlike calbindin-D28k, a delayed response of renal calbindin-D9k mRNA to 1,25(OH)2D3 was observed (the peak of induction was at 24 h after 1,25(OH)2D3 administration). Both genes in mouse kidney did not respond to glucocorticoids, although a dose-dependent decrease (12-86%) of mouse intestinal calbindin-D9k mRNA was observed after dexamethasone treatment, suggesting tissue-specific multiple steroid interactions in the regulation of calbindin gene expression. The finding of a different time course of regulation of each calbindin by 1,25(OH)2D3 suggests that different factors may be regulating the expression of the two different calbindins in mouse kidney and that elucidation of these control mechanisms should provide new insight concerning 1,25(OH)2D3-regulated gene expression.

Scanning electron microscopic study of subchondral bone tissues in osteoarthritic femoral head

During total hip replacement for 12 cases of advanced osteoarthritis of the hip joint in aged women, three types of diseased or abnormal articular cartilage with different degrees of severity (white articular cartilage, white and hyperplastic articular cartilage, and yellowish articular cartilage) and ivory bone were obtained together with their subchondral bone tissues. These specimens were processed and studied under scanning electron microscope and were compared with sex- and age-matched non-osteoarthritic femoral head articular cartilage specimens. The following findings were observed: 1. In non-osteoarthritic femoral head, the subchondral bone plate was quite thin. The bone plate connected on its deep surface with the lattice-work of trabeculae of the epiphyseal region. The trabeculae were fine and smooth and some revealed round or spindle-shaped callus resulted from microfracture. 2. In osteoarthritic femoral heads, with increased the severity of the articular lesion, the articular cartilage gradually became thinned out and eventually lost. The subchondral bone plate was markedly thickened. The epiphyseal trabeculae were also thickened and turned rough so that the lattice-work pattern gradually disappeared. The thickened trabeculae finally fused into a large piece of dense bone tissue. No microfracture was detected. These changes were attributable to the increased stress imposed on the subchondral bone tissues as a result of defective articular cartilage. Consequently, the changes on the part of the subchondral bone tissues of the osteoarthritic femoral heads were the sequent, rather than the cause, of the articular lesions.

[Characteristics of central acute resetting of low threshold baroreflex in rabbit's aortic nerve]

Experiments were performed on 40 urethane-anesthetized rabbits. The aortic nerves, carotid sinus nerves and vagus nerves were cut, mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) were recorded. The conditional stimulation (0.02 ms, 50 Hz, 4-6 V, 5 min) of central cut end of aortic nerve was used to evoke the afferent A-fibers and to mimic the response of low threshold baroreflex to holding pressure, so as to induce the central process of acute resetting. It was observed that after conditional stimulation ceased 1 min, the MAP and RSNA for response to stimulation of myelinated aortic afferent was attenuated at 41.8 +/- 7.6% (P less than 0.01, n = 11) and 19.31 +/- 2.6% (P less than 0.05, n = 11), but both MAP and RSNA were not significantly changed for non-myelinated fibers. The result suggests that the characteristics of central resetting were dependent on the component of baroreflex afferent fibers. The central resetting of low threshold myelinated afferent activities was attenuated only on the baroreflex produced by myelinated afferent fibers.

[Pathological observation of experimental asbestosis treated by hydroxy piperquin phosphate in dogs]

The paper presents experimental asbestosis treated with hydroxy piperquin phosphate (HPQP) in dogs. Results showed that the total cell number of bronchoalveolar lavage fluid, the viability of alveolar macrophages and the enzyme activities of lactate dehydrogenase, acid phosphatase and beta-glucuronidase of alveolar macrophages in treated dogs were higher than those in exposed dogs, asbestos fibers contents in the lungs and the mean scores of lung lesions in the treated dogs were markedly less than those in the exposed dogs. These findings support that HPQP may play a role in protecting alveolar macrophages from damage and inhibiting the progression of lung fibrosis, and that the clinical application of HPQP is somehow evidenced by this study.

Initiation and regulation mechanisms of ribosomal RNA transcription in the eukaryote Acanthamoeba castellanii

Acanthamoeba rRNA transcription involves the binding of a transcription initiation factor (TIF) to the core promoter of rDNA to form the preinitiation complex. This complex is formed in the absence of RNA polymerase I, and persists for multiple rounds of initiation. Polymerase I next binds to form the initiation complex. This binding is DNA sequence-independent, and is directed by protein-protein contacts with TIF. DNA melting occurs in a separate step. In contrast to most prokaryotic transcription, melting occurs only following nucleotide addition and beta-gamma hydrolysis of ATP is not required as for polymerase II. Growth-dependent regulation of rRNA transcription is accomplished by modification of RNA polymerase I. The inactive form of polymerase (PolE) is unable to bind to the promoter and has altered heat stability. PolE is still active in elongation; thus, the modification affects the polymerase site involved in TIF contact. Modification of a polymerases I and III common subunit has been detected leading to the suggestion that transcription of stable RNAs of the ribosome might be co-regulated by this mechanism.

The statistical correlation of nucleotides in protein-coding DNA sequences

The statistical correlation of nucleotides in a DNA sequence is described by a set of redundancies D1, D2, D3, . . . . By calculation of [Dn] of 2341 coding regions of nucleic acid sequences it is demonstrated that about 2/3 of sequences has correlation length less than or equal to 2, 10% of sequences--correlation with 3-periodicity and others--long range aperiodic correlations. The implications of the results from the interactions of random mutation and natural selection are discussed briefly.

Differentiation of macrophage precursors to cells with LAK activity under the influence of CSF-1 and high dose IL-2

Mouse macrophage precursor cells with natural killer (NK) like activity, derived from in vitro culture of light-fraction-bone marrow cells in the presence of colony-stimulating factor 1 (CSF-1) and low dose IL-2, were incubated with high dose (1000 U/ml) IL-2. After 3 days of incubation, cells had developed from NK like (killing Yac-1 but not P815) into LAK-like (killing both YAC-1 and P815) effector cells. Morphological studies revealed that LAK activity occurred at the time when macrophage precursors with NK like activity containing few cytoplasmic granules had further differentiated into cells with abundant azurophilic granules in their cytoplasma. Proliferation of macrophage-precursor derived NK/LAK-like cells was dependent on the presence of colony-stimulating factor, generation of cytoplasmic granules was induced by IL-2 in a dose dependent way. Flow cytometric analysis showed that macrophage precursor-derived LAK effectors were positive for NK 1.1 but almost negative for F4/80. When the same starting cell population was cultured in the presence of 200 U/ml Interferon gamma (IFN gamma), proliferation was completely stopped and within 3-4 days all cells differentiated into mature macrophages expressing F4/80. In context with our previous data, we describe here a continuum of development from agranular macrophage precursors to granular cells with NK-like activity and further to cells with LAK activity under the influence of CSF-1 as growth factor and IL-2 as granule- and cytotoxicity-inducing factor.

A conserved sequence element in ribonuclease III processing signals is not required for accurate in vitro enzymatic cleavage

Ribonuclease III of Escherichia coli is prominently involved in the endoribonucleolytic processing of cell and viral-encoded RNAs. Towards the goal of defining the RNA sequence and structural elements that establish specific catalytic cleavage of RNase III processing signals, this report demonstrates that a 60 nucleotide RNA (R1.1 RNA) containing the bacteriophage T7 R1.1 RNase III processing signal, can be generated by in vitro enzymatic transcription of a synthetic deoxyoligonucleotide and accurately cleaved in vitro by RNase III. Several R1.1 RNA sequence variants were prepared to contain point mutations in the internal loop which, on the basis of a hypothetical 'dsRNA mimicry' structural model of RNase III processing signals, would be predicted to inhibit cleavage by disrupting essential tertiary RNA-RNA interactions. These R1.1 sequence variants are accurately and efficiently cleaved in vitro by RNase III, indicating that the dsRNA mimicry structure, if it does exist, is not important for substrate reactivity. Also, we tested the functional importance of the strongly conserved CUU/GAA base-pair sequence by constructing R1.1 sequence variants containing base-pair changes within this element. These R1.1 variants are accurately cleaved at rates comparable to wild-type R1.1 RNA, indicating the nonessentiality of this conserved sequence element in establishing in vitro processing reactivity and selectivity.

The N-methyl-D-aspartate antagonist, MK-801, fails to protect against neuronal damage caused by transient, severe forebrain ischemia in adult rats

The neuroprotective effects of dizocilipine maleate (MK-801), a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor/channel, were tested in the 4-vessel occlusion rat model of forebrain ischemia. Adult Wistar rats, treated intraperitoneally with MK-801 or saline using several different treatment paradigms were subjected to 5 (n = 208) or 15 (n = 62) min of severe, transient forebrain ischemia. In saline-treated animals, 15 min of ischemia (n = 13) produced extensive and consistent loss of pyramidal neurons in the CA1 zone of hippocampus. The degree and distribution of cell loss were not reduced by single dose preischemic administration of MK-801 at 1 (n = 7), 2.5 (n = 4), or 5 mg/kg (n = 8). In other animals subjected to 15 min of forebrain ischemia, multiple doses of MK-801 (5, 2.5, and 2.5 mg/kg) given immediately and at approximately 8 and 20 hr after cerebral reperfusion (n = 5) did not alter CA1 injury compared to saline-treated controls (n = 5). Five minutes of forebrain ischemia in saline-treated animals, (n = 82) resulted in significantly fewer (p less than 0.001) dead CA1 pyramidal cells and a greater variance compared to animals subjected to 15 min of ischemia. Power analysis of the preliminary saline-treated animals subjected to 5 min of ischemia (n = 22) indicated that 60 animals per group were necessary to detect a 15% difference between MK-801 and vehicle-treated groups. Multidose treatment with MK-801 (1 mg/kg) given 1 hr prior to 5 min of ischemia (n = 60) and again at approximately 8 and 16 hr after recirculation failed to attenuate hippocampal injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of a methyl farnesoate binding protein in hemolymph from Libinia emarginata

Hemolymph from Libinia emarginata was tested for its ability to bind methyl farnesoate (MF), a JH-like compound found in many crustaceans. Hemolymph bound MF with moderate affinity (KD = 4.5 x 10(-6) M). Competitive binding studies showed that this binding was specific for MF, with farnesoic acid and JH homologues having less than 30 and 7%, respectively, of the relative binding activity of MF. JH acid and ecdysterone had no binding activity. MF binding activity was lost after pretreatment of hemolymph with heat or protease, suggesting that the binding component was a protein. Gel filtration analysis showed that the binding activity had a molecular weight of about 650,000.

Temperature dependence of plasmin-induced activation or inhibition of human platelets

It is known that at 37 degrees C plasmin may have two opposite effects on platelets: at high concentrations (greater than 1.5 caseinolytic units [CU]/mL), plasmin activates platelets; at lower concentrations (0.1 to 1.0 CU/mL) it inhibits platelet activation induced by thrombin, collagen, or calcium ionophore A23187. In this study, we report that when lowering the incubation temperature to 22 degrees C, plasmin at low concentrations (0.1 to 0.5 CU/mL) fully activated platelets. When platelets were treated with 0.2 CU/mL of plasmin, lowering the incubation temperature from 37 degrees C to 22 degrees C resulted in an increase in the expression of fibrinogen receptors, in platelet release and aggregation. Thromboxane A2 was not generated by plasmin treatment at either temperature. Ultrastructural studies showed that platelets responded to low-dose plasmin at 37 degrees C by forming pseudopods, centralizing granules without fibrinogen release, whereas at 22 degrees C the same dose of plasmin caused platelet degranulation with the appearance of alpha-granule fibrinogen within the lumen of the surface connected canalicular system. In addition, at 22 degrees C plasmin at doses insufficient to induce platelet aggregation potentiated platelet response to thrombin. Thus, we suggest that plasmin may initiate both activating and inhibitory processes within platelets and that the change of temperature could influence this balance. These results may be of clinical relevance, because the fibrinolytic system was found activated during cardiopulmonary bypass in which the temperature of patient's blood circulation was reduced. This temperature-dependent behavior is also an interesting model for a further study on platelet response to serine proteinases.

[Small-airway lesions induced by inhalation of asbestos dust in dogs--pathological and aetiological studies]

This paper presents the pathological changes of the small airways of dogs inhaling asbestos dust in the workshop of Xin Kong Asbestos Mine for 1 to 3 years. Dogs of the experimental group showed that variable degrees of dust deposition and fibrous tissue reaction were found in all the three types of the small airways-respiratory bronchioles, alveolar ducts and membranous bronchioles of both lungs. The lesions in the lung increased with the duration of exposure. These changes in the canine small airways resulting from asbestos dust were very much similar to those of the humans. In addition, deposited dust collected from the workshop of the asbestos mine, and 50 dust particles selected randomly in foci were identified in situ by energy dispersive X-ray analysis. Findings demonstrated that the majority of the dust particles in the foci was principally mixed silicate dust. Among them asbestos dust predominated absolutely, and there were more amphiboles than chrysotiles. Therefore, it is concluded that the small airway lesions induced in the dogs are mainly due to mixed asbestos dust, and that there appears to exist a dose-response relationship.

Circadian rhythms of body temperature and drinking and responses to thermal challenge in rats after PCPA

Body temperature (Tb) and drinking were measured for five days in male and female rats. On day 6 (S1) the rats were injected with saline. On day 7 (P1) they were injected with PCPA (300 mg/kg IP). Measurements continued for 12 days. Immediately after PCPA Tb dropped. After that, the amplitude of the daily Tb rhythm was significantly decreased from days P2-P5. Females were more affected than males. Nocturnality of drinking was decreased on days P2-P4. Because the peak of the Tb rhythm advanced after PCPA, while the peak of the drinking rhythm was delayed, we conclude that the attenuation of the Tb rhythm was a direct result of PCPA treatment rather than a masking effect due to the attenuation of other rhythms. Other rats were thermally challenged during the first week post-PCPA. There were no differences in ability to regulate Tb in the cold, and the small variations in the heat were overshadowed by gender differences.