Impact of a school-based AIDS prevention program on risk and protective behavior for newly sexually active students

This project assessed the impact of a school-based AIDS prevention program on student participation in sexual risk and protective behaviors such as use of condoms and use of condoms with foam and intention to participate in such behaviors. The paper focuses on students who became sexually active for the first time between the seventh and eighth grade ("changers," n = 312). The school-based intervention was developed using social cognitive theory and the social influences model of behavior change. Using an experimental, longitudinal design, 15 high-risk school districts were divided randomly into two treatment (10 districts) and one control (five districts) conditions. Students in both treatment conditions received a 10-lesson classroom program in the seventh grade with a five-lesson booster in the eighth grade, while control students received basic AIDS education (current practice in their districts) in compliance with state mandates. Results indicated classroom programs had an impact on certain protective behaviors and on frequency of sexual activity the past month. Post-intervention measures also indicated the program affected students' intentions to perform specific protective behaviors.

Interaction with pig ileal explants of Escherichia coli O45 isolates from swine with postweaning diarrhea

We have previously observed that Escherichia coli O45 isolates from swine postweaning diarrhea (PWD) induced attaching-effacing (A/E) lesions in experimentally inoculated gnotobiotic piglets. In the present work, ileal explant culture has been used as an in vitro model for the study of the development of A/E lesions due to these isolates. The characteristic intimate bacterial attachment and microvilli effacement with cupping and pedestal formation, identical to that observed in gnotobiotic piglets, was demonstrated in pig ileal explants inoculated with O45 E. coli isolates. The initial attachment of bacteria to the enterocytes was observed from 2 to 4 h postinoculation (PI) and full development of A/E lesions was observed within 8 h PI. In this model, we observed that 22 of 25 eaeA-positive O45 isolates induced A/E lesions. However, A/E lesions were not observed for any of 7 eaeA-negative O45 isolates. Thus, we describe a useful in vitro model for the study of A/E capacity of porcine E. coli. Use of this model has enabled us to demonstrate the relatedness of the eaeA gene to A/E capability among porcine O45 E. coli from PWD.

Effects of cassava starch on the property of artificial endosperm and on the germination of artificial seeds

Effects of 4 polymers on the property of artificial endosperm and on the germination of artificial seeds were studied. Results showed that complexed endosperm made from 1% cassava starch and 1.5% alginate improve the ventilation and imbibition properties of artificial seeds made from alginate only and enhanced the germination rate of artificial seeds.

Characterization of coding ends in thymocytes of scid mice: implications for the mechanism of V(D)J recombination

We previously identified possible intermediates in V(D)J recombination at the TCR delta locus and characterized molecules with signal ends and with covalently sealed (hairpin) coding ends in thymocytes of scid mice by Southern blotting. Here, we use a sensitive ligation-mediated PCR assay to demonstrate that all coding ends detected in scid thymocytes are covalently sealed. Neither coding nor signal ends exhibit loss or addition of nucleotides. These data imply that hairpin formation is coupled to the initial cleavage at the signal/coding border, and that the cleavage step in V(D)J recombination is conservative. In scid/+ or wild-type thymocytes, hairpin coding ends are at least 1000-fold less abundant than signal ends. These results provide insight into the mechanism of V(D)J recombination.

A longitudinal comparison of the AIDS-related attitudes and knowledge of parents and their children

As part of an evaluation of an experimental school-based AIDS risk-reduction program, data from 2,392 middle-school students in 15 high-risk school districts and from 1,627 of their parents were compared to examine how young adolescents and their parents differ with respect to AIDs-related knowledge and attitudes. At the time of the seventh-grade pretest, parents knew significantly more about AIDS than their children did. At the eighth-grade posttest, students who participated in the program knew either more than or at least as much as their parents in several subject areas, while among those not exposed to the program, parents still knew more than their children in most areas. The intervention had a positive impact on students' attitudes toward people with AIDS and on their degree of comfort about discussing with their parents such issues as drug use and sexuality.

A comparison of AIDS-defining events and subsequent CDC stage IV events in IDUs and gay men

The two major risk groups for acquisition of HIV in the UK are gay men and IDUs. Individuals from these risk groups vary in a number of respects in their life-style, which have the potential to affect the course of their HIV disease. This study compares gay men and IDUs from the Lothian Region of Scotland with respect to their AIDS defining diagnosis and subsequent CDC (Centers for Disease Control) stage IV events. Comparisons were made between the two risk groups for their AIDS defining diagnosis by performing chi square tests, Mann-Whitney tests and logistic regression. Subsequent CDC stage IV events were analysed using ordinal logistic regression and Cox regression. 89 IDUs and 56 gay men were included in the analysis. Oesophageal candida was a commoner AIDS-defining diagnosis in IDUs than gay men and Kaposi's sarcoma was diagnosed more frequently in gay men than IDUs. Subsequently oesophageal candida was also commoner in IDUs and CMV retinitis was seen more frequently in gay men. The role of prophylaxis and differences in diet are discussed as possible causes of the observed differences in the incidence of oesophageal candida. The higher incidence of CMV retinitis in gay men probably reflects the high level of sexual acquisition of CMV.

Virulence properties and attaching-effacing activity of Escherichia coli O45 from swine postweaning diarrhea

Escherichia coli O45 isolates associated with swine postweaning diarrhea in Québec were characterized with respect to virulence determinants genetically and investigated for their attaching and effacing (A/E) activities by experimental inoculation of gnotobiotic piglets and by the HEp-2 cell adherence assay. All of 32 isolates tested were negative for enterotoxigenic and verotoxigenic E. coli virulence determinants, heat-labile enterotoxin (LT), heat-stable enterotoxins (STap, STb), verotoxins (VT1, VT2), and F4 (K88), F5 (K99), F6 (987P), and F41, except one STb-positive and two F4-positive isolates. A total of 25 isolates hybridized with an EaeA probe, and 11 hybridized with an enteropathogenic E. coli adherence factor (EAF) probe. None of 32 isolates hybridized with a bundle-forming pilus (BFP) probe. The EAF, EaeA, and BFP factors have been associated with human enteropathogenic E. coli strains. A total of 10 of 12 eaeA-positive porcine O45 isolates induced A/E lesions characterized by intimate adherence of bacteria to the intestinal epithelial cell membrane with effacement of the microvilli, similar to those of human attaching-effacing E. coli. However, A/E lesions were not observed in the piglets inoculated with any one of three eaeA-negative O45 isolates. All E. coli O45 isolates were non-adherent to HEp-2 cells. Thus, we have demonstrated the production of typical A/E lesions by nonenterotoxigenic E. coli O45 isolates from swine postweaning diarrhea. The results indicate the significance of the eaeA gene in A/E activities of these isolates and suggest that EAF and BFP are not involved in O45 E. coli infection of weaning piglets.

Regulation of adhesion molecule expression in Kaposi's sarcoma cells

Kaposi's sarcoma (KS) is a neoplasm with multifocal vascular lesions that is often seen in homosexual HIV-infected individuals. Infiltrates of leukocytes are characteristic components of KS lesions, and the products of leukocytes have been shown to enhance the proliferation of KS cells in vitro and most likely are crucial for the development of KS lesions in vivo. It is therefore likely that the expression of cellular adhesion molecules (CAM) is a critical determinant in the pathogenesis of KS by dictating the numbers and types of leukocytes that accumulate in areas predisposed to KS. We report that in the absence of inducers, KS cells in culture expressed low levels of ICAM-1 and undetectable VCAM-1 and E-selectin. ICAM-1, VCAM-1, and E-selectin were all induced by dsRNA (poly (I:C)), IL-1 beta, TNF-alpha, and LPS in KS cells. All of these agents increased NF-kappa B binding activity in nuclear extracts from KS cells. Neither human dermal fibroblasts nor human aortic smooth muscle cells had detectable VCAM-1 protein expression in response to conditions that led to high levels of VCAM-1 expression in KS cells. Although E-selectin expression was induced in KS cells, the peak cell surface protein levels were less than 25% the levels achieved on HUVEC or human dermal microvascular endothelial cells (HMEC). These low levels resembled the levels that were induced in HMEC immortalized with SV 40 large T Ag. These data indicate that multiple proinflammatory agents can induce NF-kappa B binding activity and can enhance ICAM-1, VCAM-1, and E-selectin expression in KS cells. The increased CAM expression enhances leukocyte binding to KS cells. Thus, the induction of CAM expression could be an early event in the development of KS by recruiting leukocytes into KS lesions, thereby providing factors that could potentiate the development of KS.

Regulation of adhesion molecule expression in Kaposi's sarcoma cells

Kaposi's sarcoma (KS) is a neoplasm with multifocal vascular lesions that is often seen in homosexual HIV-infected individuals. Infiltrates of leukocytes are characteristic components of KS lesions, and the products of leukocytes have been shown to enhance the proliferation of KS cells in vitro and most likely are crucial for the development of KS lesions in vivo. It is therefore likely that the expression of cellular adhesion molecules (CAM) is a critical determinant in the pathogenesis of KS by dictating the numbers and types of leukocytes that accumulate in areas predisposed to KS. We report that in the absence of inducers, KS cells in culture expressed low levels of ICAM-1 and undetectable VCAM-1 and E-selectin. ICAM-1, VCAM-1, and E-selectin were all induced by dsRNA (poly (I:C)), IL-1 beta, TNF-alpha, and LPS in KS cells. All of these agents increased NF-kappa B binding activity in nuclear extracts from KS cells. Neither human dermal fibroblasts nor human aortic smooth muscle cells had detectable VCAM-1 protein expression in response to conditions that led to high levels of VCAM-1 expression in KS cells. Although E-selectin expression was induced in KS cells, the peak cell surface protein levels were less than 25% the levels achieved on HUVEC or human dermal microvascular endothelial cells (HMEC). These low levels resembled the levels that were induced in HMEC immortalized with SV 40 large T Ag. These data indicate that multiple proinflammatory agents can induce NF-kappa B binding activity and can enhance ICAM-1, VCAM-1, and E-selectin expression in KS cells. The increased CAM expression enhances leukocyte binding to KS cells. Thus, the induction of CAM expression could be an early event in the development of KS by recruiting leukocytes into KS lesions, thereby providing factors that could potentiate the development of KS.

Characterization of broken DNA molecules associated with V(D)J recombination

We previously demonstrated that DNA molecules with double-strand breaks at variable-(diversity)-joining [V(D)J] recombination signal sequences are relatively abundant in mouse thymocytes. This abundance strongly suggests that the mechanism of V(D)J recombination involves double-strand cleavage at recombination signals. As a first step toward understanding the mechanism of cleavage, we used a sensitive PCR assay to characterize the structure of one class of cleavage products, the signal ends, in detail. Here we demonstrate that most of these ends are blunt and terminate in 5' phosphoryl groups. Virtually all of the flush signal ends are full length. A minor subpopulation of broken ends terminates in short single-strand extensions. We have found no evidence for covalent DNA-protein linkages involving the signal ends. These data allow further refinement of the double-strand cleavage model for V(D)J recombination.

Angiotensin-converting enzyme inhibitors have no effect on ovulation and ovarian steroidogenesis in the perfused rat ovary

The null hypothesis of this study was that the angiotensin-converting enzyme inhibitors, captopril and teprotide, would not reduce the number of ovulations in vivo and in vitro in the rat. Captopril (in three regimens) was administered continuously beginning prior to pregnant mare's serum gonadotropin and hCG to trigger ovulation. The number of in vivo ovulations were counted. Ovaries similarly primed with pregnant mare's serum gonadotropin were dissected and perfused in media with hCG and captopril (two regimens) or teprotide (one regimen). The number of in vitro ovulations and steroid production in the perfusions were evaluated. The results were evaluated by the Student's t test. Power calculations gave only a 20% chance of missing a 16% difference in ovulations or steroidogenesis. There was no inhibition of ovulation or change in steroid production in angiotensin-converting enzyme treated rats in vivo or in vitro. While angiotensin II has been shown to be an important mediator in the mechanism of ovulation, angiotensin-converting enzyme inhibition via captopril or teprotide does not result in angiotensin II antagonistic effects. Hypothetical mechanisms to explain this paradox are presented.

Determination of adhesion force between single cell pairs generated by activated GpIIb-IIIa receptors

A biophysical approach was used to directly determine the avidity of the junction between two Chinese hamster ovary (CHO) cells bearing recombinant GpIIb-IIIa in the presence and absence of fibrinogen. Micromanipulation was used to induce conjugation of the cell pairs with or without activating the GpIIb-IIIa molecules with monoclonal antibody (MoAb) 62. Activation of GpIIb-IIIa caused an increase in the force required to separate the conjugates. The molecular bonding force between cells bearing activated GpIIb-IIIa and fibrinogen molecules was found to be 2.1 x 10(-7) dyne, which is 3.7 times higher than that between nonactivated GpIIb-IIIa and fibrinogen (5.7 x 10(-8) dyne). The results provide a quantitative assessment of the molecular bonding force between fibrinogen and the GpIIb-IIIa expressed on cell surface. The findings indicate that the activation of GpIIb-IIIa leads to an increase in the adhesive force in CHO cell aggregation by increasing the strength of the GpIIb-IIIa-fibrinogen bonds rather than the number of these bonds.

The angiotensin II antagonist saralasin inhibits ovulation in the perfused rat ovary

OBJECTIVE

Our null hypothesis was that the angiotensin II antagonist saralasin does not reduce the number of ovulations in the rat ovarian perfusion model.

STUDY DESIGN

Ovaries from pregnant mare's serum gonadotropin-stimulated immature rats were perfused with nutrient media to which luteinizing hormone and 3-isobutyl-1-methylxanthine had been added to induce ovulation. Test perfusions were treated with saralasin 1 mumol/L (n = 0.5) and compared with controls (n = 5) with the Student t test. Perfusions with both saralasin and angiotensin II and dose-response evaluations were performed.

RESULTS

Saralasin-treated ovulations were 6.6 +/- 1.3 (mean + SEM) compared with 18.6 +/- 3.9, p < 0.02. The effects of saralasin could be reversed with the addition of an equimolar amount of angiotensin II. Dose-response evaluations showed a progressive inhibition of ovulation at 10(-8) to 10(-6) mol/L.

CONCLUSION

The angiotensin II antagonist saralasin inhibits ovulation in a dose-dependent fashion; this effect is canceled by the addition of equimolar concentrations of angiotensin II.

A region of antisense RNA from human p120 cDNA with high homology to mouse p120 cDNA inhibits NIH 3T3 proliferation

The human nucleolar p120 protein is a proliferation-associated antigen which is expressed in G1 and peaks during the early S phase of the cell cycle. Overexpression of the human p120 protein caused the transformation of NIH 3T3 cells and expression of an antisense p120 construct inhibited the growth of NIH 3T3 cells (Perlaky et al., Cancer Res., 52:428-436, 1992). The middle region of the antisense p120 RNA was found to be almost as inhibitory as the full length antisense construct but the 5' and 3' antisense portions did not affect NIH 3T3 cell proliferation. After the mouse p120 complementary DNA was cloned and sequenced, comparison with the human p120 complementary DNA showed a striking conservation of 85% of the nucleotide sequence and 96% of the amino acid sequence. The two ends of the p120 molecule had less homology in their nucleotide and amino acid sequences. Based on this homology, the observed inhibitory effects of the middle portion of antisense human p120 RNA may be related to suppression of mouse p120 expression by RNA:RNA duplex formation. The high evolutionary conservation of the middle region suggests it has a critical role for the function of this protein.

[Studies on the technological process for preparing medicated leaven]

This paper takes as index the content of free acids and total acids, the action of pepsin in the stomachs of hungry mice, impelling functions and intestines of hungry mice and makes a comparison of the raw products with the processed products of medicated leaven. It is suggested that bran-perched or burnt perched leaven is better for invigorating the function of the spleen and promoting digestion.

Effects of thyrotropin-releasing hormone on acute experimental traumatic head injury in cats

The effects of thyrotropin-releasing hormone (TRH) on early acute traumatic head injury in cats were evaluated by continuous intravenous infusion of TRH (2 mg/kg/h) or saline (2 ml/kg/h) for four hours, beginning one hour after injury. The results showed that TRH, administered intravenously, significantly increased the mean arterial pressure and cerebral perfusion pressure, decreased intracranial pressure, alleviated brain edema, and reduced the mortality rate. These effects promoted the recovery of neurologic function following traumatic head injury. Because of the significant central action and the ability to antagonize many pathophysiological effects of endogenous opioids or exogenous opiates except their analgesic effects, TRH and its analogues have broad prospects in the treatment of patients with CNS injuries or shock.

Changes of immunoreactive TRH in cerebrospinal fluid and plasma after acute head injury and its clinical significance

Using radioimmunoassay (RIA) concentrations of immunoreactive TRH (TRH-ir) in cerebrospinal fluid (CSF) and plasma were determined after acute head injury in 29 patients. The results showed that the concentrations of TRH-ir (pmol/L) in CSF and plasma on the days when injuries were sustained were 29.25 +/- 8.92 pg/ml and 30.29 +/- 8.26 (1 pg/ml = 2.8 pmol/L) in mildly (n = 12), 57.78 +/- 11.72 and 65.27 +/- 8.57 in moderately (n = 9), and 70.09 +/- 7.58 and 85.65 +/- 7.92 in severely (n = 8), head-injured patients. While the concentrations of TRH-ir in CSF and plasma were 25.11 +/- 11.85 and 27.90 +/- 11.39 in the control group (n = 10). Dynamic observations revealed that the contents of TRH-ir in CSF and plasma were gradually recovered to their control levels when improvement of the head-injured patients took place. But they were significantly decreased and became much lower than the control levels in patients with poor prognosis. These results suggest that the assay of TRH-ir in CSF and plasma has clinical significance in reflecting the severity and prognosis of acute head-injured patients.

A tissue inhibitor of metalloproteinases and alpha-macroglobulins in the ovulating rat ovary: possible regulators of collagen matrix breakdown

Immature female Sprague-Dawley rats were primed with 20 IU eCG at 28 days of age and treated with 10 IU hCG 48 h later. Ovulation followed at 12-14 h. Ovaries were extracted at various times after hCG by use of Triton X-100 and 10 mM CaCl2 (Triton extract) followed by heating to 60 degrees C for 6 min with 0.1 M CaCl2 in 50 mM Tris/0.15 M NaCl, pH 7.5 (heat extract). These extracts were tested for their ability to inhibit tissue metalloproteinases by use of the small uterine metalloproteinase (UMP) of the rat. The ovary contains three plasma-derived inhibitors (alpha 1-macroglobulin [alpha 1 M], alpha 2-macroglobulin [alpha 2 M], and alpha 1 inhibitor3 [alpha 1I3]) and one tissue-derived inhibitor of the tissue inhibitor of metalloproteinases (TIMP) family. alpha 1 I3 was shown to inhibit UMP and rat collagenase. The concentration of the tissue inhibitor rose 5-fold from 0.6 micrograms UMP blocked per gram wet tissue in ovaries not primed with eCG to 3.2 micrograms UMP blocked at 8 h after hCG. Over this same time interval, the sum of alpha 1M + alpha 2M per gram of ovary rose 7-fold from 3.2 to 22.4 micrograms UMP inhibited and alpha 1I3 rose 2-fold from 4.4 to 10.7 micrograms UMP inhibited. The increases in the tissue inhibitor are interpreted to be due to increased synthesis by the tissue, whereas the changes in alpha-macroglobulins are postulated to be due to increased vascularity and increased permeability of the vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of ovulation in the perfused rat ovary by the synthetic collagenase inhibitor SC 44463

A new, powerful, synthetic inhibitor of mammalian tissue collagenases and related metalloproteinases is inhibitory to ovulation in perfused rat ovaries. Ovaries of immature rats, primed with 20 IU of eCG, were dissected and perfused with 0.1 micrograms/ml LH and 0.2 mM 3-isobutyl-1-methylxanthine (IBMX) for 20 h. Addition of SC 44463 (N4-hydroxy-N1-[1S [(4-methoxphenyl)methyl]-2-(methylamino)-2-oxoethyl]- 2R-(2-methylpropyl)butane-diamide) at a concentration of 25 nM inhibited ovulation by 55% (9.6 +/- 1.7 ovulations per ovary, mean +/- SEM, compared to a control value of 21.7 +/- 1.7); and 250 nM inhibited ovulation by 75% (5.3 +/- 1.1 ovulations per ovary). We previously showed that the related compound SC 40827 inhibited ovulation by 70% when used at a concentration of 25 microM (Brännström et al., Endocrinology 1988; 122:1715-1721). We now show that SC 44463 is 100, 500, and 75 times more powerful than SC 40827 in blocking ovulation, inhibiting action of ovarian interstitial collagenase, and inhibiting action of the small metalloproteinase of the rat uterus, respectively. SC 44463 also inhibits ovarian type IV collagen-digesting activity 50% at a concentration of 18 nM. Ovulation occurs after 9-12 h of perfusion with LH. Compound SC 44463 (25 nM) showed its full inhibitory capacity when added to the medium as late as 7 h after LH, but there was no significant inhibition when it was added at 9 h. This suggests that the major collagenolytic events occur beyond 7 h after stimulation by LH.

A thermodynamic and biomechanical theory of cell adhesion. Part I: General formulism

The equilibrium thermodynamics calculus of cell adhesion developed by Bell et al. (1984, Biophys. J. 45, 1051-1064) has been extended to the general non-equilibrium case. In contrast to previous models which could only compute the end results of equilibrium states, the present theory is able to calculate the kinetic process of evolution of adhesion, which may or may not approach towards equilibrium. Starting from a basic constitutive hypothesis for Helmholtz free energy, equations of balance of normal forces, energy balance at the edge of the contact area and rate of entropy production are derived using an irreversible thermodynamics approach, in which the restriction imposed by the Second Law of Thermodynamics takes the place of free energy minimization used by Bell et al. (1984). An explicit expression for adhesion energy density is derived for the general transient case as the difference of the usable work transduced from chemical energy liberation from bond formation of specific crosslinking molecules and the repulsive potential of non-specific interactions. This allows the energy balance to be used as an independent boundary equation rather than a practical way of computing the adhesion energy. Jump conditions are obtained from the conservation of crosslinking molecules across the edge of adhesion region which is treated as a singular curve. The bond formation and lateral motion of the crosslinking molecules are assumed to obey a set of reaction-diffusion equations. These equations and the force balance equation within the contact area, plus the jump conditions and the energy balance equation at the edge form a well-posed moving boundary problem which determines the propagation of the adhesion boundary, the separation distance between the two cell membranes over the contact area as well as the distributions of the crosslinking molecules on the cell surfaces. The behavior of the system depends on the relative importance of virtual convection, lateral diffusion and bond formation of the crosslinking molecules at the edge of the adhesion region, according to which two types of rate limiting cases are discussed, viz, reaction-limited and diffusion-limited processes.

Feasibility of using liquid crystals for the development of molecularly selective fiber-optic chemical sensors

A new type of fiber-optic chemical sensor has been developed for the determination and differentiation of geometric isomers. The operation of the sensor is based upon the molecular-geometric-selective absorption of polynuclear aromatic hydrocarbons (PAH) on a liquid crystal. The selective interaction of a PAH with a liquid-crystal substrate causes quenching of the liquid-crystal fluorescence. Detection limits of such a device for PAH compounds approach 10(-10) mol/cm3; the sensor response time is about 2 min. Because the sensor is based upon physical absorption, it is reusable and reversible.

Passive deformations and active motions of leukocytes

The purpose of this paper is to review the development of continuum mechanics models of single leukocytes in both passive deformations and active motions and to indicate some future directions. Models of passive deformations describe the overall rheological behavior of single leukocytes under externally applied forces and predict the average mechanical properties from experimental data. Various "apparent" viscoelastic coefficients are obtained depending on the models assumed and the types of test used. Models of spontaneous motions postulate active driving mechanisms which must be derived internally from the cell itself and probably have different bases for different kind of motions. For pseudopod protrusion on leukocytes, energy transduction from chemical potential to mechanical work associated with actin polymerization at the tip of the projection is assumed to supply the motive power. For pseudopod retraction, active contraction due to actin-myosin interaction is assumed to be the driving force. The feasibility of the hypotheses are tested via numerical examples and comparison of the theoretical results with experimental measurements.

Rheological aspects of red blood cell aggregation

The rheological aspects of red blood cell aggregation include molecular phenomena, cell viscoelasticity, and bulk flow rheology. At the molecular level, rates at which bonds are formed and broken, the chemical energy liberation from bond formation, the elasticity of the cross-bridges and lateral mobility of cross-linking molecules must all be considered for a complete description of bond formation and distribution. Lateral migration of binding molecules occurs due to diffusion in the surface of the membrane but may also be influenced by the stresses in the membrane during separation of adhering cells. In red blood cell disaggregation, fluorescent probes have shown concentration of ligands in the region of contact close to the line of separation. The chemical potential decrement that occurs when a bond is formed provides the energy source that may deform red blood cells in the process of aggregation. The degree of aggregation and the extent of cell deformation depends on the viscoelastic properties of the cell as well as the dynamics of bond formation and repulsive potential of surface charges present, which is governed by an equation representing a balance of these energies. In flowing blood, the hydrodynamic forces applied by the plasma and surrounding cells must be added to the bond forces and elastic response of the cell. Under sufficiently strong aggregation, plug flow or large aggregates may result. At high shear rates, aggregation may be prevented due to the small contact time and high shear stresses so that no effects of aggregation may be observed. At intermediate shear stresses, transitory contact, adhesion and disaggregation may occur between neighboring cells. Such phenomena have not been analyzed in detail, but simplified models suggest that plug-like flow can occur due to hydrodynamic cell-cell interaction even when cells are not aggregated.

Connective tissue breakdown in ovulation

A meshwork of collagen over the apical region of the follicle must be breached to permit the ovum to escape. We propose that specific collagenase activity is responsible for collagen breakdown in this region. Immature rats are primed with pregnant mare serum gonadotropin (PMSG), followed at 48 h by hCG. At 8 h after hCG, collagenase activity, measured in extracts of ovarian tissue, is elevated about five-fold. Ovulation follows at 10-12 h. Ovaries from PMSG-primed rats are dissected at 48 h, placed in a perfusion apparatus, and perfused with luteinizing hormone and 3-isobutyl-1-methyl xanthine. The ovulations induced by this treatment can be blocked to the extent of 70% with a synthetic collagenase inhibitor. The activation of procollagenase is believed to involve plasminogen activator and plasmin. In support of this, we find that tranexamic acid at 1 mM inhibits ovulation about 70%. The inhibitor must be added within 3-4 h of LH to be effective. A specific plasmin inhibitor, D-Val-Phe-Lys-chloromethyl ketone, is similarly effective.

[Effect of naloxone on experimental head injury in cats]

Forty-five cats were randomly divided into four groups: (1) the control group (n = 11); (2) the head injury group (n = 17); (3) the naloxone group (n = 8); (4) the saline group (n = 9). Naloxone (10mg/kg) was directly injected into cisterna cerebello-medullaris 2 hours after injury. The results showed that naloxone had some effects in maintaining MABP, CPP, lowering of ICP and edema of brain).

Human interstitial retinoid-binding protein. Gene structure and primary structure

Interstitial retinoid-binding protein (IRBP) is synthesized and secreted by rod photoreceptor cells into the interphotoreceptor matrix and is known to bind retinoids and fatty acids. We have used cDNA clones encoding human IRBP to isolate a 15-kilobase genomic fragment that encompasses the complete human IRBP gene. The IRBP gene spans more than 11 kilobases and is interrupted by three introns, all of which are positioned near the 3'-end of the coding sequence. The 3741-base pair coding region of IRBP appears to have been generated by quadruplication of an approximately 900 base pair long ancestral gene. The deduced amino acid sequence predicts a mature protein of 1,230 residues (calculated molecular weight 133,000). The protein sequence can be aligned into four homologous segments, each consisting of about 300 residues. Sequence similarity between segments is as high as 60% when conservative substitutions are taken into account. Two putative N-linked glycosylation sites are located in highly conserved domains in the center of the first and second segment of IRBP. A domain consisting of 41 residues at the COOH-terminal end of the third segment has 15 matching residues (38%) with an intradiscal loop of rhodopsin, a retinal-binding protein in rod photoreceptors.

Beta-endorphin-like immunoreactivity in CSF of patients with acute head injury. A clinical report of 36 cases

beta-endorphin-like immunoreactivity (beta-ELI) was measured in the cerebrospinal fluid (CSF) of 36 patients with acute head injury and 12 controls. The mean values of beta-ELI in CSF of controls and patients with moderate and severe acute head injury were 51.9 +/- 5.6 pg/ml, 110.5 pg/ml, and 173.8 +/- 20.1 pg/ml respectively, with significant difference between them (p less than 0.05). The results showed that beta-ELI increased in CSF of acute head injury patients.

One-dimensional steady continuum model of retraction of pseudopod in leukocytes

A one-dimensional steady state continuum mechanics model of retraction of pseudopod in leukocytes is developed. The retracting pseudopod is assumed to move bodily toward the main cell body, the bulk motion of which can be represented by cytoplasmic flow within a typical stream tube through the leukocyte. The stream tube is approximated by a frictionless tube with prescribed geometry. The passive rheological properties of cytoplasm in the main cell body and in the pseudopod are modeled, respectively, by Maxwell fluid and Hookean solid. The two regions are assumed to be separated by a sharp interface at which actin gel solates and thereby changes its rheological properties as it flows from the pseudopod to the main cell body. The driving mechanism responsible for the active retraction motion is hypothesized to be a spontaneous deformation of the actin gel, analogous but not necessarily equal to the well known actin-myosin interaction. This results in an active contractile stress being developed in the pseudopod as well as in the cell cortex. The transverse traction pulls against the inclined wall of the stream tube and is transduced into an axial stress gradient, which in turn drives the flow. The tension on the tube wall is picked up by the prestressed cortical shell. Governing equations and boundary conditions are derived. A solution is obtained. Sample data are computed. Comparison of the theory with experiments shows that the model is compatible to the observations.

[A preliminary study on pollinating bees for Amomum compactum Soland ex Maton]

This article deals with the species of bees pollinating Amomum compactum, along with the laws governing their growth and decline, and the pollinating effect of Nomia and Ceratina in the field.

A continuum model of protrusion of pseudopod in leukocytes

The morphology of human leukocytes, the biochemistry of actin polymerization, and the theory of continuum mechanics are used to model the pseudopod protrusion process of leukocytes. In the proposed model, the pseudopod is considered as a porous solid of F-actin network, the pores of which are full of aqueous solution. G-actin is considered as a "solute" transported by convection and diffusion in the fluid phase. The pseudopod grows as actin filaments elongate at their barbed ends at the tip of the pseudopod. The driving force of extension is hypothesized as being provided by the actin polymerization. It is assumed that elongation of actin filaments, powered by chemical energy liberated from the polymerization reaction, does mechanical work against opposing pressure on the membrane. This also gives rise to a pressure drop in the fluid phase at the tip of the pseudopod, which is formulated by an equation relating the work done by actin polymerization to the local state of pressure. The pressure gradient along the pseudopod drives the fluid filtration through the porous pseudopod according to Darcy's Law, which in turn brings more actin monomers to the growing tip. The main cell body serves as a reservoir of G-actin. A modified first-order equation is used to describe the kinetics of polymerization. The rate of pseudopod growth is modulated by regulatory proteins. A one-dimensional moving boundary problem based on the proposed mechanism has been constructed and approximate solutions have been obtained. Comparison of the solutions with experimental data shows that the model is compatible with available observations. The model is also applicable to growth of other cellular systems such as elongation of acrosomal process in sperm cells.

A t(8;14)(q24;q11) translocation in a T-cell leukemia (L1-ALL) with c-myc and TcR-alpha chain locus rearrangements

Cell lines established from T-cell leukemias have recently been reported to exhibit a chromosome translocation t(8;14) involving proto-oncogene c-myc and the gene of the T-cell receptor alpha-chain(TcR-alpha). In this work, we have studied a case of T-cell leukemia presenting a t(8;14)(q24;q11) translocation that was found in fresh leukemic cells taken during relapse, but was absent in cells collected at diagnosis. Hybridization analysis showed that the breakpoint on chromosome 8 was located 3' to the c-myc exon 3. A TcR-alpha-specific original probe (D14S7, Mathieu-Mahul et al., 1985) revealed two differently rearranged patterns in DNA from leukemic cells obtained at diagnosis and during relapse. In contrast, the rearranged TcR-beta-gene DNA pattern did not change during the course of the disease, indicating that leukemic cells were clonally related. These data indicate that the chromosome breakpoint in 14q11 is situated in the TcR-alpha locus. These results suggest that translocations t(8;14) involving TcR-alpha and c-myc genes in T-cell malignancies are analogous to variant t(2;8) and t(8;22) translocations observed in Burkitt lymphoma. They also establish that the same types of molecular rearrangements due to a t(8;14)(q24;q11) translocation, at first described in T-cell lines established in culture, also exist in vivo and may play a role in the evolution of the leukemic process.