Studies of human platelet ultrastructure and quantitative analyses of membrane glycoprotein IIB/IIIA in shear stress-induced platelet quick release reaction

The ultrastructural characteristics of platelets and the quantitative analysis of membrane glycoprotein (GP) IIb/IIIa quick-release reaction induced by high shear stress (HSS) were studied with transmission electron microscope and immunocolloidal gold staining. The results showed that platelets were activated and aggregated by HSS (50 dynes/cm2 or 100 dynes/cm2). Besides, HSS also caused a special platelet quick-release reaction which was called granule-membrane-fused lytic release (GFLR). GFLR differed from releases I and II which were induced by ADP and thrombin respectively. Granules were released quickly and lysis occurred when all granules had been discharged in GFLR. GFLR is a special form of platelet quick release induced by HSS and is called release III by the authors. In the process of platelet activation and lysis, the gold particles of GPIIb/IIIa were increasingly condensed. The possible reasons of increased surface expression of GPIIb/IIIa stimulated by HSS are also discussed.

Delta 9-tetrahydrocannabinol produces naloxone-blockable enhancement of presynaptic basal dopamine efflux in nucleus accumbens of conscious, freely-moving rats as measured by intracerebral microdialysis

This study examined the effects of acute administration of delta-9-tetrahydrocannabinol (delta 9-THC), the psychoactive ingredient in marijuana, on extracellular efflux of dopamine (DA) and its metabolites as measured by in vivo microdialysis in nucleus accumbens of conscious, freely-moving rats. delta 9-THC, at low doses (0.5-1.0 mg/kg), which significantly enhance brain stimulation reward (intracranial self-stimulation), significantly increased DA efflux in nucleus accumbens. Augmentation of DA efflux by delta 9-THC was abolished by removal of calcium (Ca++) ions from the perfusion fluid, indicating a Ca(++)-dependence of delta 9-THC's action. Augmentation of DA efflux by delta 9-THC was either totally blocked or significantly attenuated by doses of naloxone as low as 0.1 mg/kg. Given the postulated role of mesocorticolimbic DA circuits in mediating and/or modulating brain stimulation reward, the present data raise the possibility that marijuana's rewarding effects, and hence its euphorigenic effects and abuse potential, may be related to pharmacological augmentation of presynaptic DA mechanisms. Additionally, the DA mechanisms enhanced by marijuana appear to be modulated by an endogenous opioid peptide system.

On the relationships between rural labor productivity, family investment in education, and population quality

The authors consider "the relationships between labor productivity and population quality in order to demonstrate the importance of economic development, and of improving population quality in rural areas. This study is made on the basis of surveys conducted in 1979 and 1986 on the age-specific VP and VC [volume of production and volume of consumption] in certain areas of Jiangsu Province [China]." Population quality is defined primarily in terms of the educational status of the labor force.

Transcapillary oncotic pressure in the edema of congestive heart failure

Tissue fluid and plasma oncotic pressure levels were measured in an unselected group of 13 patients presenting with congestive heart failure. Patients had a mean serum albumin of 3.6 g/dl +/- (SD) 0.35; serum oncotic pressure was 22.23 +/- 1.8 mm Hg; tissue fluid (lower leg) oncotic pressure was 0.985 +/- 0.34 mm Hg. The oncotic pressure gradient between plasma and tissue fluid was 21.25 Hg +/- 1.7. This is about 10 mm Hg greater than delta pi in normal man. The high value in congestive heart failure is a mechanism to protect against the formation of edema. The possible mechanisms responsible for the formation of edema in congestive heart failure are discussed.

Fertility of fresh and frozen rabbit semen inseminated at different times is indicative of male differences in capacitation time

Some reports indicate that sperm from different males differ in capacitation time, and other reports suggest that freezing sperm may affect their capacitation time. These two variables were specifically studied in rabbits in a fertility trial with 96 does inseminated with approximately 1.6 million motile fresh or frozen sperm from three different bucks at 15, 10, 5, and 0 h before expected ovulation. Fresh semen averaged 84% live (unstained) sperm and 88% had normal acrosomes; corresponding values for frozen sperm were 44% and 54%. On the basis of does that became pregnant, average litter size with fresh semen was 5.5 and with frozen semen was 4.8 (p greater than 0.05), but overall, does bred with frozen semen produced fewer young (p less than 0.05). On the basis of total does and total semen, average litter size from insemination at 15, 10, 5, and 0 h was 2.8, 4.2, 3.8, and 1.7, and average litter size for the three bucks was 4.0, 1.8, and 3.6. There was no interaction of type of semen (fresh or frozen) with the other variables in the model (p greater than 0.05). Bucks and time of insemination affected both the proportion of does that were pregnant and litter size (p less than 0.01). A major interaction between buck and time of insemination (p less than 0.01) was due apparently to both differential sperm survival and probable capacitation time among bucks. This major interaction should be considered in designing in vitro and in vivo fertility studies, and for selecting males for use in artificial insemination.

The micronucleus test and erythropoiesis. Effects of erythropoietin and a mutagen on the ratio of polychromatic to normochromatic erythrocytes (P/N ratio)

It is considered that a decrease of the ratio of polychromatic erythrocytes (PCE) to normochromatic erythrocytes (NCE) (P/N) in the micronucleus test is an indicator of bone marrow toxicity induced by mutagens. However, the exact meaning of fluctuation in the P/N ratio is not yet known. We have studied this point by counting the total number of erythrocytes and nucleated cells in the bone marrow following various treatments. The P/N ratio decreased gradually with time after administration of mitomycin C. Our data suggest that the decrease of P/N ratio was attributable to an increase in the numbers of the denominator, i.e. NCE, caused by rapid differentiation and multiplication or denucleation of erythroblasts which remained in the bone marrow instead of entering the peripheral blood stream. A decrease of P/N ratio was also observed in the early phase after administration of erythropoietin, an agent which induces differentiation and multiplication of erythroblasts. This phenomenon might result from an increase of PCE delivery into the blood circulation. However, following the initial decrease, the P/N ratio increased gradually 48 h after administration of erythropoietin. It is supposed that this increase probably resulted from an increase in PCE in the bone marrow due to the direct effects of erythropoietin on erythropoiesis. The drastic change in erythropoiesis in the bone marrow induced by either mutagen or erythropoietin treatment will affect the fluctuations of the P/N ratio or the number of micronucleated erythrocytes per non-micronucleated erythocytes in the micronucleus test. This contrasts with the original explanation for such fluctuations which attributed them to replenishment of the marrow by peripheral blood.

An exponential ESS model and its application to frequency-dependent selection

A nonlinear ESS model is put forward, that is, a nonnegative exponential ESS model. For a simple case, we discuss the existence, uniqueness, and stability of an ESS. As an application of the model, we give a quantitative analysis of frequency-dependent selection in population genetics when the rare type has an advantage.

[A quantitative study of human platelet membrane glycoproteins using immunocolloidal gold under the electron microscope]

Two human platelet membrane glucoproteins (GP) and the quantitative changes of them induced by high shear stress (HSS) were studied using SZ-2 and SZ-21 monoclonal antibodies against GPIb and GPIIb/IIIa respectively by means of immunocolloidal gold technique with electron microscopy. Exposure to HSS (50 dynes/cm2, 5 min; 100 dynes/cm2, 3 min) resulted in the transformation of platelets from native smooth discs to activated spiny spheres followed by the centralization of organelles and lysis or aggregation of platelets. The results showed that resting platelets with few gold probes were turned into activated platelets by HSS with increased gold probes which represent the quantity of GPIb or GPIIb/IIIa. HSS also caused a specific platelet reaction--lysis. In the process of platelet lysis, platelet GPIIb/IIIa were increasingly condensed. On the contrary, GPIb reduced gradually. It suggests that the increase of GPIIb/IIIa under HSS may be one of the causes inducing platelet adhesion, release and aggregation at the opening of branched vessels, curved arteries, stenosed or partially occluded arteries due to local spasm.

Oedema protein concentrations for differentiation of cellulitis and deep vein thrombosis

The differentiation between cellulitis and deep vein thrombosis was investigated in a series of patients with acutely swollen, painful, red legs. Oedema-fluid protein concentrations (as mean [SD]) were significantly higher in patients with cellulitis than in those with deep vein thrombosis (19.8 g/l [5.0] vs 5.85 g/l [1.6]), and the oncotic pressure of oedema-fluid was also significantly higher in cellulitis (6.3 mm Hg [1.3] vs 2.1 mm Hg [0.6]). In hospitals where phlebography, plethysmography, or doppler ultrasound are not available, measurement of oedema-fluid protein concentrations may be a rapid and inexpensive guide to the cause of a red, swollen leg.

[Observation on enhanced adhesion to dentin by amino acid]

An amino acid was adopted to pretreat the surface of dentin. The bond strength between GP adhesive and dentin mediated by the amino acid was enhanced after the pretreatment. Furthermore, the longer the stored time of extracted tooth was, the better the effect of adhesion was. This pretreatment will benefit the adhesive restoration for dead tooth or low activity tooth clinically.

Relative adherence of Bacteroides species and strains to Actinomyces viscosus on saliva-coated hydroxyapatite

The study was designed to compare the adherence of several Bacteroides species to A. viscosus. Using 3H, we labeled 24 laboratory strains, including 13 Bacteroides species and 11 fresh clinical isolates of three Bacteroides species. Their adherence to A. viscosus bound to a saliva-coated mineral surface was quantified by liquid scintillation. Adherence relative to a standard strain, B. gingivalis 2561, was compared. Among the lab bacteroides, those of B. gingivalis (eight strains) were the greatest binders (mean, 80.5 +/- 12.4%). Strains of other lab bacteroides bound less well (mean, 33.4 +/- 6.3%). The difference in means was statistically significant (p less than 0.01). The mean for B. gingivalis strains was also significantly greater than that for strains of B. intermedius (51.7 +/- 6.2%). Attachment of B. gingivalis was saturable in experiments in which either input concentration or time was the independent variable, indicating that B. gingivalis cells do not accumulate in this vitro simulation of plaque formation by binding to each other. Subculture did not seem to affect the degree of binding.

Proteolytic processing of a coleopteran-specific delta-endotoxin produced by Bacillus thuringiensis var. tenebrionis

Insecticidal protein delta-endotoxin crystals harvested from sporulated cultures of Bacillus thuringiensis var. tenebrionis contain a major polypeptide of 67 kDa and minor polypeptides of 73, 72, 55 and 46 kDa. During sporulation, only the 73 kDa polypeptide could be detected at stage I. The 67 kDa polypeptide was first detected at stage II and increased in concentration throughout the later stages of sporulation and after crystal release, with a concomitant decrease in the 73 kDa polypeptide. This change could be blocked by the addition of proteinase inhibitors. Trypsin or insect-gut-extract treatment of the delta-endotoxin crystals after solubilization resulted in a cleavage product of 55 kDa with asparagine-159 of the deduced amino acid sequence of the toxin [Höfte, Seurinck, van Houtven & Vaeck (1987) Nucleic Acids Res. 15, 71-83; Sekar, Thompson, Maroney, Bookland & Adang (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 7036-7040; McPherson, Perlak, Fuchs, Marrone, Lavrik & Fischhoff (1988) Biotechnology 6, 61-66] at the N-terminus. This polypeptide was found to be as toxic in vivo as native delta-endotoxin.

[Inhibition of release of prostaglandins and leukotrienes from calcimycin-induced mouse peritoneal macrophages and bovine aorta endothelial cells by anisodamine]

[3H]Arachidonic acid (AA)-prelabeled mouse peritoneal macrophages were stimulated by calcium ionophore A-23187 to release [3H]AA metabolites. The major labeled products which were co-chromatographed with the authentic PG and LT standards by TLC and determined by liquid scintillation were 6-keto-PGF1 alpha, PGE2, LTC4, and LTB4. Anisodamine (Ani) significantly inhibited the A-23187-induced release of PG and LT from mouse macrophages in a dose-dependent manner. In the presence of Ani at 0.5 mmol/L, the A-23187-induced release of 6-keto-PGF1 alpha, PGE2, LTC4 and LTB4 was reduced by 57%, 20%, 53% and 49%, respectively. A-23187-induced release of 6-keto-PGF1 alpha measured by RIA from bovine aorta endothelial cells was also significantly inhibited by Ani in a dose-dependent manner. These results indicate that the calcium-antagonistic effects of Ani may not only play a significant role in its inhibiting release of PG and LT, but also contribute to its salutary effects in the treatment of septic shock.

Overproduction of the protein encoded by the maize transposable element Ac in insect cells by a baculovirus vector

The polypeptide encoded in the Activator (Ac) element of Zea mays L. has been expressed in Spodoptera frugiperda insect cells using plasmids which carry the strong polyhedrin promoter of the baculovirus Autographa californica nuclear polyhedrosis virus (AcNPV). Recombinant AcNPVs with the Ac-cDNA integrated and under the control of the viral polyhedrin promoter have been isolated and their genomes have been partly characterized as to the location of the foreign DNA insert. Upon infection of S. frugiperda cells with the recombinant AcNPV, maize Ac element specific messenger RNAs, as well as a newly synthesized polypeptide with an apparent molecular weight of about 116 kDa, have been detected in extracts of recombinant infected cells. This polypeptide is absent from extracts of wild-type infected cells expressing the polyhedrin polypeptide which can be recognized by the presence of nuclear inclusion bodies. Recombinant infected cells lack this protein. The Ac specific polypeptide is detected by antisera, which have been raised against fusion proteins containing Ac sequences synthesized in Escherichia coli, both in immunoprecipitation and in Western blotting experiments. The Ac specific protein is a nuclear phosphoprotein and represents about 1%-2% of the newly synthesized protein.

Purification and properties of the NusB protein of Escherichia coli

Mutations in the nusB gene of Escherichia coli block transcriptional antitermination mediated by the N gene protein of bacteriophage lambda. We describe here two methods of overproducing the NusB protein in E. coli and a method of purifying NusB to apparent homogeneity on a large scale. Purified NusB directly stimulates transcriptional antitermination by the lambda N protein in vitro. It behaves as a monomer (Mr = 15,689) during gel permeation chromatography and gradient sedimentation. The number of NusB molecules in a wild type E. coli K12 cell ranges from about 3,000 to about 6,000 molecules/cell, depending on the growth medium, and is about 50-80% of the number of molecules of the core component of RNA polymerase in the cell. This implies that NusB has a major role in regulating chain elongation during the transcription of E. coli genes. Many E. coli strains with nusB mutations cannot grow at low temperature. However, a sup+ strain with the suppressible amber mutation nusBam115 can grow at 42 degrees C. Since such a strain does not produce NusB protein detectable by immunoprecipitation with anti-NusB, normal amounts of NusB are not essential for the survival of E. coli at 42 degrees C.

Trace element content in drinking water of nasopharyngeal carcinoma patients

Chinese in the Xiangxi region of Hunan province in China have a high incidence of nasopharyngeal carcinoma (NPC). For analyzing the relation between NPC and trace elements, the concentrations of 7 trace elements in drinking water (well water) of high- and low-incidence areas were measured (75 samples). The results showed that the concentrations of Ni, Zn and Cd in drinking water of high-incidence areas were significantly higher than those in low-incidence areas. Especially, the Ni level in drinking water had a significant positive correlation with NPC mortality. These observations are consistent with earlier studies. We also found a highly positive correlation between Ni/pH value in drinking water and NPC mortality. This suggests that only considering the ion concentration in drinking water is not enough, we should also pay attention to the pH of the drinking water when we study the relation between NPC and trace elements. Because the pH of the medium can strongly affect trace element chemical characteristics and its metabolic state in living systems, the M/pH (M, metal concentration) may be an important factor worthy of further research.

An elongation control particle containing the N gene transcriptional antitermination protein of bacteriophage lambda

The N gene transcriptional antitermination protein of bacteriophage lambda is incorporated in vitro into transcriptional elongation complexes containing the E. coli proteins NusA and NusB. The binding of NusA to elongating RNA polymerase is sequence-independent and follows the release of sigma 70. Incorporation of N into the elongation complex requires an N utilization site (nut site) on the DNA template. Incorporation of NusB into the complex requires NusA, ribosomal protein S10, and the boxA component of the nut site. T1 RNAase releases N, but not NusB, from the elongation complex. We therefore propose that an N-modified termination-resistant elongation complex includes an elongation control particle (ECP) containing at least NusA, NusB, S10, N, and an RNA transcript of the nut site.