Altered behavior and long-term potentiation in type I adenylyl cyclase mutant mice

The murine Ca(2+)-stimulated adenylyl cyclase (type I) (EC 4.6.1.1), which is expressed predominantly in brain, was inactivated by targeted mutagenesis. Ca(2+)-stimulated adenylyl cyclase activity was reduced 40-60% in the hippocampus, neocortex, and cerebellum. Long-term potentiation in the CA1 region of the hippocampus from mutants was perturbed relative to controls. Both the initial slope and maximum extent of changes in synaptic response were reduced. Although mutant mice learned to find a hidden platform in the Morris water task normally, they did not display a preference for the region where the platform had been when it was removed. These results indicate that disruption of the gene for the type I adenylyl cyclase produces changes in behavior and that the cAMP signal transduction pathway may play an important role in synaptic plasticity.

[The significance of fascial tissue of the upper eyelid in double eyelidplasty]

The anatomical structure of fascial tissue of the upper eyelid is described in this article. It is emphasized that removing redundant fascial tissue is an important procedure in the double-eyelid operation of the upper eyelid. This is especially true for patients with baggy deformities or blepharochalasis. Based on this principle, 654 cases of double eyelidplasty were performed from 1990 to 1993 with satisfactory results revealed by postoperative follow-up of 1 month to 3 years.

Aggregation efficiency of activated normal or fixed platelets in a simple shear field: effect of shear and fibrinogen occupancy

Shear rate can affect protein adsorption and platelet aggregation by regulating both the collision frequency and the capture efficiency (alpha). These effects were evaluated in well defined shear field in a micro-couette for shear rate G = 10 - 1000 s-1. The rate of protein binding was independent of G, shown for adsorption of albumin to latex beads and PAC1 to activated platelets. The initial aggregation rate for ADP-activated platelets in citrated platelet-rich plasma followed second order kinetics at the initial platelet concentrations between 20,000 and 60,000/microliters. alpha values, which dropped nearly fivefold for a 10-fold increase in G, were approximately proportional to G-1, contrary to a minor drop predicted by the theory that includes protein cross-bridging. Varying ADP concentration did not change alpha of maximally activated platelet subpopulations, suggesting that aggregation between unactivated and activated platelets is negligible. Directly blocking the unoccupied but activated GPIIb-IIIa receptors without affecting pre-bound Fg on "RGD"-activated, fixed platelets (AFP) by GRGDSP or Ro 43-5054 eliminated aggregation, suggesting that cross-bridging of GPIIb-IIIa on adjacent platelets by fibrinogen mediates aggregation. Alpha for AFP remained maximal (approximately 0.24) over 25-75% Fg occupancy, otherwise decreasing rapidly, with a half-maximum occurring at around 2% occupancy, suggesting that very few bound Fg were required to cause significant aggregation.

Flow-induced detachment of red blood cells adhering to surfaces by specific antigen-antibody bonds

Fixed spherical swollen human red blood cells of blood type B adhering on a glass surface through antigen-antibody bonds to monoclonal mouse antihuman IgM, adsorbed or covalently linked on the surface, were detached by known hydrodynamic forces created in an impinging jet. The dynamic process of detachment of the specifically bound cells was recorded and analyzed. The fraction of adherent cells remaining on the surface decreased with increasing hydrodynamic force. For an IgM coverage of 0.26%, a tangential force on the order of 100 pN was able to detach almost all of the cells from the surface within 20 min. After a given time of exposure to hydrodynamic force, the fraction of adherent cells remaining increased with time, reflecting an increase in adhesion strength. The characteristic time for effective aging was approximately 4 h. Results from experiments in which the adsorbed antibody molecules were immobilized through covalent coupling and from evanescent wave light scattering of adherent cells, imply that deformation of red cells at the contact area was the principal cause for aging, rather than local clustering of the antibody through surface diffusion. Experiments with latex beads specifically bound to red blood cells suggest that, instead of breaking the antigen-antibody bonds, antigen molecules were extracted from the cell membrane during detachment.

Hysterectomy in the United States, 1988-1990

OBJECTIVE

To describe patient characteristics and diagnoses associated with hysterectomy in the United States from 1988-1990 using data from the National Hospital Discharge Survey.

METHODS

We analyzed data from the National Hospital Discharge Survey, an annual probability sample of discharges from nonfederal, short-stay hospitals in the United States. A population-based sample of all women aged 15 years or older in the United States civilian population who had a hysterectomy during 1988-1990 was examined to characterize factors associated with hysterectomy: patients' age and race, diagnoses, surgical approach, and oophorectomy.

RESULTS

Approximately 1.7 million women had a hysterectomy during 1988-1990. The highest rates--100.5 hysterectomies per 10,000 women--were for women aged 30-54 years. Total rates of hysterectomy for black women were similar to those for white women (61.7 and 56.5 per 10,000 women, respectively); uterine leiomyoma ("fibroid tumor") was reported as the primary diagnosis for 61% of black women and 29% of white women. Abdominal surgery was used for 75% of all hysterectomies. Concomitant bilateral oophorectomy was done for 37% of the women under 45 years old and 68% of the women 45 years or older.

CONCLUSIONS

Two-thirds of all hysterectomies for noncancerous conditions were performed for uterine leiomyoma or endometriosis--conditions that are most common before the age of menopause. Future assessments of the appropriateness of hysterectomy will require better understanding of these disorders. Continued monitoring of hysterectomy rates is critical to understanding the appropriate use of hysterectomy, alternative therapies for uterine disorders, and future trends in women's health care.

Polymetallic macromolecules are potential contrast agents of improved efficiency

The commercial synthetic homopolypeptide polyaspartate (average MW = 30,000, approximately 220 monomers) in solution quantitatively binds up to 40 mol Gd3+ ions per mole of polyaspartate. The water proton relaxivity of the solutions is far higher than that of clinically used or commonly investigated gadolinium(III) complexes. It is shown that polymetallic macromolecular complexes combine the high relaxing efficiency of monometallic macromolecular complexes with the favorable metal/ligand mass ratio of small monometallic complexes.

Surveillance for ectopic pregnancy--United States, 1970-1989

PROBLEM/CONDITION

From 1970 through 1989, hospitalizations for ectopic pregnancy have increased in the United States; the number of cases has increased fivefold, from 17,800 to 88,400.

REPORTING PERIOD COVERED

1970-1989.

DESCRIPTION OF SYSTEM

Reported ectopic pregnancies were estimated from data collected by CDC's National Center for Health Statistics (NCHS) as part of the ongoing National Hospital Discharge Survey. Data from responding hospitals were weighted to represent national estimates. The number of deaths resulting from ectopic pregnancy was based on U.S. vital statistics collected by NCHS. Denominators for calculating ectopic pregnancy rates were the total number of reported pregnancies, which includes live births, legal induced abortions, and ectopic pregnancies. Data for live births were obtained from NCHS natality statistics and data for legal induced abortions from CDC's Division of Reproductive Health.

RESULTS

From 1970 through 1989, more than one million ectopic pregnancies were estimated to have occurred among women in the United States; the rate increased by almost fourfold, from 4.5 to 16.0 ectopic pregnancies per 1,000 reported pregnancies. Although ectopic pregnancies accounted for < 2% of all reported pregnancies during this period, complications of this condition were associated with approximately 13% of all pregnancy-related deaths. During this period, the risk of death associated with ectopic pregnancy decreased by 90%: the case-fatality rate declined from 35.5 deaths per 10,000 ectopic pregnancies in 1970 to 3.8 in 1989. The risks of ectopic pregnancy and death from its complications were consistently higher for blacks and other racial/ethnic minorities than for whites throughout the period.

INTERPRETATION

Although the general trend has been for the numbers and rates of ectopic pregnancy to increase over the 20-year period, the variability of the data does not permit meaningful conclusions to be made about year-to-year changes in the estimates of ectopic pregnancies, especially for the years 1988 and 1989.

ACTIONS TAKEN

These findings indicate the need to characterize behaviors and risk factors that may respond to preventive interventions. Until these risks factors are better characterized, early detection and appropriate management of ectopic pregnancies will remain the most effective means of reducing the morbidity and mortality associated with this condition.

Expression of two different forms of cDNA for thromboxane synthase in insect cells and site-directed mutagenesis of a critical cysteine residue

cDNA coding for human placental thromboxane synthase (EC 5.3.99.5) was amplified by PCR from a human placental cDNA library and sequenced. This cDNA and a shorter cDNA isolated from a human lung cDNA library with a deletion of 163 bp near the 3' end were expressed in Spodoptera frugiperda (Sf9) insect cells using a baculovirus expression system. The cDNA from human placenta was expressed as an active enzyme (60 kDa) with a specific activity higher than those reported from other cell types, whereas the shorter cDNA was expressed in an inactive form (52 kDa). The active recombinant enzyme appeared to be unglycosylated as the molecular mass and the enzyme activity were not altered in the presence of tunicamycin. Site-directed mutagenesis was performed to convert a cysteine at position 480 in thromboxane synthase to a serine. This cysteine is found to be highly conserved in related cytochrome P-450 enzymes. The mutant enzyme was found to be inactive, although Western blot, immunoprecipitation and SDS/PAGE analysis indicated that the mutant enzyme was expressed at a level comparable with the wild-type enzyme. These results suggest that Cys-480 is essential for the enzyme catalytic activity and that the short-form cDNA may be a non-functional transcript.

Kinetics of specific and nonspecific adhesion of red blood cells on glass

Fixed spherical human red blood cells suspended in 17% sucrose were allowed to adhere on either clean glass surfaces or glass surfaces preincubated with antibodies specific to a certain blood group antigen. The adhesion experiments were performed in an impinging jet apparatus, in which the cells are subjected to stagnation point flow. The objective of this study was to compare the efficiencies of nonspecific and specific (antigen-antibody mediated) adhesion of red blood cells on glass surfaces. The efficiency was defined as the ratio of the experimental adhesion rate to that calculated based on numerical solutions of the mass transfer equation, taking into account hydrodynamic interactions as well as colloidal forces. The efficiency for nonspecific adhesion was nearly unity at flow rates lower than 85 microliter/s (corresponding to a wall shear rate, Gw, of 30 s-1 at a radial distance of 110 microns from the stagnation point). The values of efficiency dropped at higher flow rates, due to an increase in the tangential force. The critical deposition concentration is found to occur at 120-150 mM NaCl, which is consistent with the theoretically predicted values. At low salt concentrations, the experimental values are higher than the theoretical ones. Similar discrepancies have been found in many colloidal systems. Introducing steric repulsion by adsorbing a layer of albumin molecules on the glass completely prevents nonspecific adhesion at flow rates below 60 microliter/s (Gw congruent to 15 s-1). The efficiency of specific adhesion depends both on the concentration of antibody molecules on the surface and the flow rate. Normal red cells adhere more readily through antigen-antibody bonds than fixed cells. Fixed spherical cells have a higher adhesion efficiency than fixed biconcave ones.

Cloning, chromosomal mapping, and expression of human fetal brain type I adenylyl cyclase

The neural-specific calmodulin-sensitive adenylyl cyclase (type I), which was first cloned from bovine brain, has been implicated in learning and memory. The objective of this study was to clone and determine the chromosomal localization of human fetal brain type I adenylyl cyclase. A 3.8-kb cDNA clone was isolated that contained sequence coinciding with the 3' end 2553 nucleotides of the bovine open reading frame. This clone shows 87% nucleotide and 92% translated amino acid sequence identity to the bovine clone. The most significant sequence differences were in the carboxy-terminal 100 amino acid residues. This region contains one of several possible calmodulin binding domains and the only putative cAMP-dependent protein kinase A phosphorylation site. A chimera was constructed that contained the 5' half of the bovine type I adenylyl cyclase and the 3' half of the human type I adenylyl cyclase. The activity of the chimeric gene product and its sensitivity to calmodulin and calcium were indistinguishable from those of the bovine type I adenylyl cyclase. In situ hybridization was used to localize the human type I adenylyl cyclase gene to the proximal portion of the short arm of chromosome 7.

The regulatory diversity of the mammalian adenylyl cyclases

Clones for six mammalian adenylyl cyclases have recently been isolated. One of these enzymes, the type I calmodulin-sensitive adenylyl cyclase, is neurospecific and is implicated in neuroplasticity. We propose that the type I adenylyl cyclase may be important for learning and memory because it allows Ca(2+)-amplified cAMP signals, synergism between Ca2+ and cAMP-activated kinases, and positive feedback regulation of Ca2+ channels by cAMP-dependent protein kinase.

[In vitro effect of alveolar macrophages of dust-exposed rabbit on lung fibroblasts (V79)]

This is a study of the interactions between rabbit alveolar macrophages (AM) and Chinese hamster lung fibroblasts (V79) mediated by Xinkang chrysotile asbestos, UICC Canadian chrysotile B asbestos, quartz and pure titanium dioxide on (1) fibroblast proliferation, (2) collagen synthesis and (3) morphological changes. In comparison with the control, the results of 3H-TdR incorporation, histochemical staining and quantitative microscopic observation of V79 cell suggested that the supernatants of AM treated by the four kinds of dust could stimulate the proliferation and collagen accumulation of V79 cell group. As to the degree of fibrosis resulting from the dust, Xinkang asbestos was noted to be similar to quartz but stronger than UICC asbestos; the effect of TiO2 was the weakest.

Type I calmodulin-sensitive adenylyl cyclase is neural specific

The distribution of type I calmodulin-sensitive adenylyl cyclase in bovine and rat tissues was examined by northern blot analysis and in situ hybridization. Northern blot analysis using poly(A)(+)-selected RNA from various bovine tissues indicated that mRNA for type I adenylyl cyclase was found only in brain, retina, and adrenal medulla, suggesting that this enzyme is neural specific. In situ hybridization studies using bovine, rabbit, and rat retina indicated that mRNA for type I adenylyl cyclase is found in all three nuclear layers of the neural retina and is particularly abundant in the inner segment of the photoreceptor cells. The neural-specific distribution of type I adenylyl cyclase mRNA and its restricted expression in areas of brain implicated in neuroplasticity are consistent with the proposal that this enzyme plays an important role in various neuronal functions including learning and memory.

The type III calcium/calmodulin-sensitive adenylyl cyclase is not specific to olfactory sensory neurons

A cDNA clone for type III adenylyl cyclase was originally isolated from a rat olfactory cDNA library and Northern analysis using total RNA suggested that the expression of the type III mRNA may be limited to the olfactory epithelium (Bakalyar and Reed, Science, 250 (1990) 1403-1406). In this study, the distribution of type III adenylyl cyclase mRNA in a number of bovine tissues and cultured cells was examined by Northern analysis using poly(A)+ RNA. Type III adenylyl cyclase mRNA was expressed in brain, spinal cord, adrenal medulla, adrenal cortex, heart atrium, aorta, lung, retina, 293 cells and PC-12 cells. Furthermore, the Ca2+ sensitivity of adenylyl cyclase activity in 293 cells indicated the presence of type III adenylyl cyclase. These data indicate that expression of the type III adenylyl cyclase is not limited to olfactory tissues, and that this enzyme probably has a number of physiological functions in addition to olfactory signal transduction.

Stimulation of the type III olfactory adenylyl cyclase by calcium and calmodulin

Characterization of adenylyl cyclases has been facilitated by the isolation of cDNA clones for distinct adenylyl cyclases including the type I and type III enzymes. Expression of type I adenylyl cyclase activity in animal cells has established that this enzyme is stimulated by calmodulin and Ca2+. Type III adenylyl cyclase is enriched in olfactory neurons and is regulated by stimulatory G proteins. The sensitivity of the type III adenylyl cyclase to Ca2+ and calmodulin has not been reported. In this study, type III adenylyl cyclase was expressed in human kidney 293 cells to determine if the enzyme is stimulated by Ca2+ and calmodulin. The type III enzyme was not stimulated by Ca2+ and calmodulin in the absence of other effectors. It was, however, stimulated by Ca2+ through calmodulin when the enzyme was concomitantly activated by either GppNHp or forskolin. The concentrations of free Ca2+ for half-maximal stimulation of type I and type III adenylyl cyclases were 0.05 and 5.0 microM Ca2+, respectively. These data suggest that the type III adenylyl cyclase is stimulated by Ca2+ when the enzyme is activated by G-protein-coupled receptors and that increases in free Ca2+ accompanying receptor activation may amplify the primary cyclic AMP signal.

Microrheological aspects of adhesion of Escherichia coli on glass

The adhesion of both live and fixed bacteria (Escherichia coli) on glass has been studied under well-defined hydrodynamic conditions, created in an impinging jet apparatus. With this technique one can accurately measure the initial deposition rate jo on the surface, the average lifetime of a bacterium on the surface, tau esc, and the surface area blocked per deposited bacterium, normalized by its projected area, gamma. The experimental results are compared to theoretical results for equivalent spheres. It is found that near the stagnation point the deposition rate jo is mainly controlled by convective diffusive transport which, for rod-shaped Eschericia coli, with an axis ratio of about 2, is found to be equal to that for spheres. No differences in jo and tau esc were found between live and fixed bacteria at low flow rates. At high flow rates fixed bacteria adhered to the surface at a slower rate. In both systems jo was found to decrease suddenly at a distance of about 150 microns from the stagnation point, in contrast to systems of spherical particles for which jo is uniform over the surface. Most likely this is due to the rotation of the rod-shaped particles, which vary their distance to the surface periodically with time. The main difference between live and fixed bacteria, besides different deposition rates in strong flows, is that gamma is about 30% larger for fixed bacteria than for live ones, resulting in a much lower final coverage for fixed bacteria. These results imply a larger repulsion between fixed bacteria than between living ones. From detachment experiments we can conclude that not all bacteria stick to the surface with the same bond strength. The variation in the bond strength is due to the aging of the bonds between the bacteria and the surface. The average bond strength corresponds to an energy of about 13-15 kT.

Preliminary X-ray crystallographic study of methanol dehydrogenase from Methylophilus methylotrophus

Single crystals of methanol dehydrogenase from Methylophilus methylotrophus have been prepared by the macroseeding method. The crystals belong to the monoclinic space group C2, and have unit cell parameters a = 125.62 A, b = 63.83 A, c = 83.99 A, and beta = 93.24 degrees. There is one 62,000 Mr monomer in the asymmetric unit. The crystals diffract to beyond 2.0 A resolution.