Showing papers by "Medical University of South Carolina published in 1983"

Intrinsic laminar lattice connections in primate visual cortex

Abstract: Intracortical injections of horseradish peroxidase (HRP) reveal a system of periodically organized intrinsic connections in primate striate cortex. In layers 2 and 3 these connections form a reticular or latticelike pattern, extending for about 1.5-2.0 mm around an injection. This connectional lattice is composed of HRP-labeled walls (350-450 microns apart Saimiri and about 500-600 microns in macaque) surrounding unlabeled central lacunae. Within the lattice walls there are regularly arranged punctate loci of particularly dense HRP label, appearing as isolated patches as the lattice wall labeling thins further from the injection site. A periodic organization has also been demonstrated for the intrinsic connections in layer 4B, which are apparently in register with the supragranular periodicities, although separated from these by a thin unlabeled region. The 4B lattice is particularly prominent in squirrel monkey, extending for 2-3 mm from an injection. In both layers, these intrinsic connections are demonstrated by orthogradely and retrogradely transported HRP and seem to reflect a system of neurons with long horizontal axon collaterals, presumably with arborizations at regularly spaced intervals. The intrinsic connectional lattice in layers 2 and 3 resembles the repetitive array of cytochrome oxidase activity in these layers; but despite similarities of dimension and pattern, the two systems do not appear identical. In primate, as previously described in tree shrews (Rockland et al., '82), the HRP-labeled anatomical connections resemble the pattern of 2-deoxyglucose accumulation resulting from stimulation with oriented lines, although the functional importance of these connections remains obscure.

Lymphocyte heterogeneity in the trout, Salmo gairdneri, defined with monoclonal antibodies to IgM

Abstract: A monoclonal antibody to trout serum IgM was tested by immunofluorescence analysis with lymphocytes from thymus, spleen and head kidney. By visual examination, the antibody reacted with only a subpopulation of lymphocytes. The mean values +/- SE for positive cells were 5.2 +/- 2.3% in the thymus, 30.3 +/- 7.9% in the spleen and 12.4 +/- 3.0% in the head kidney. Flow cytofluorometric analysis revealed evidence of heterogeneity by size among the membrane IgM-positive cells of the head kidney and spleen. Depletion of head kidney cells positive for surface IgM by an immune affinity adherence technique of panning, using monoclonal anti-IgM, significantly reduced the mitogenic response to lipopolysaccharide but not to concanavalin A. It is suggested that this information supports the existence of distinct subpopulations of fish lymphocytes that may be homologous in certain respects to mammalian T and B type cells.

Light microscopic detection of sugar residues in glycoconjugates of salivary glands and the pancreas with lectin-horseradish peroxidase conjugates. I. Mouse.

Abstract: Salivary glands and pancreases from male rats were stained with a battery of ten different lectin-horseradish peroxidase conjugates. Qualitative and quantitative differences were observed in the content of terminal sugar residues in stored secretory glycoproteins in parenchymal cells of glands having a similar histological structure. Heterogeneity in the content of secretory glycoconjugates was also found between cells in the same exocrine glands, which were previously thought to be identical on the basis of classical morphological and histochemical staining studies. Similar differences were observed in the structure of glycoconjugates associated with the apical surface of epithelial cells lining glandular excretory ducts. Intercalated ducts presented a gland specific staining pattern different from that of the glandular secretory cell population, whereas striated duct and interlobular duct epithelial cells stained similarly in all major rat exocrine glands. A comparison of lectin binding patterns in identical histological sites in the mouse, reported in a companion paper, is provided, and the similarities and differences between these two rodent species are discussed. In addition to providing valuable information concerning the localization and structure of tissue complex carbohydrates, a comparison of staining in the same tissue sites with labelled lectins reported biochemically to have similar binding specificity has revealed interesting differences in the binding specificity of these macromolecules.

Cytology of periolivary cells and the organization of their projections in the cat.

Abstract: Projections of cells located near principal nuclei of the superior olive, periolivary cells, were studied by injecting horseradish peroxidase or fluorescent tracers into the cochlea, cochlear nucleus, and inferior colliculus. At least two distinct cytological classes of periolivary cells were found to project to each of these structures. "Large" and "small" olivocochlear cells were labelled. Their cytology and locations were found to be as had been previously described. Some olivocochlear cells also project to the cochlear nucleus. Other major periolivary cell classes that project to the cochlear nucleus include a lateral group of multipolar cells whose members are located around the ipsilateral lateral superior olive and have coarse, darkly staining Nissl substance. The other major periolivary cell class that projects to the cochlear nucleus is the small cell of the ventral nucleus of the trapezoid body. This cell is characterized by its size and by only one or two intensely staining clumps of Nissl substance. Projections of these cells to the cochlear nucleus is from both sides. Periolivary cells that project to the inferior colliculus include medial and lateral groups. Cells of the lateral group project from both sides. These cells are multipolar in shape and contain lightly staining, flocculent Nissl substance. They are predominantly located immediately ventral to the lateral superior olive. Projections from the medial group are predominantly ipsilateral and arise from the region medial to the medial superior olive. The cells are multipolar and contain clumped Nissl substance. They often lie near "large" olivocochlear cells, which they resemble in Nissl material, but are distinguished from the latter in Protargol material by having ring-type axosomatic endings. The appearance and locations of these six classes of periolivary cells make it possible to recognize them in nonexperimental material and to infer with confidence what their projections are. These results show considerable organization of these previously little understood structures.

Proliferative kinetics and differentiation of murine blast cell colonies in culture: evidence for variable G0 periods and constant doubling rates of early pluripotent hemopoietic progenitors.

Abstract: Several investigators have described hemopoietic colonies expressing multilineage differentiation in culture. We recently identified a class of murine hemopoletic progenitors which form blast cell colonies with very high replating efficiencies. In order to clarify further the relationship between progenitors for blast cell colonies and progenitors for the multilineage hemopoietic colonies in culture, we carried out analyses of kinetic and differentiation properties of murine blast cell colonies. Serial observations of the development of blast cell colonies into multilineage (and single lineage) colonies in cultures of spleen cells obtained from 5-fluorouracil (5-FU)-treated mice confirmed the transitional nature of the murine blast cell colonies. The data also suggested that the early pluripotent progenitors are in G0 for variable periods, and that when triggered into cell cycle, they proliferate at relatively constant doubling rates during the early stages of differentiation. The notion that some of the pluripotent progenitors are in G0 was also supported by long-term thymidine suicide studies in which spleen cells were exposed to 3H-thymidine with high specific activity for 5 days in culture, washed, and assayed for surviving progenitors. Comparison of replating abilities of day-7 and day-16 blast cell colonies from normal as well as 5-FU-treated mice indicated that some of the day-7 blast cell colonies are derived from maturer populations of progenitors which are sensitive to 5-FU. In contrast, progenitors for the day-16 blast cell colonies are dormant in cell cycle and were not affected by 5-FU treatment. Previously we reported that progenitors for day-16 blast cell colonies have a significant capacity for self-renewal. These observations suggest the hypothesis that the capability for self-renewal is accompanied by long periods of G0, and that once commitment to differentiation takes place, then active cell division occurs.

Histochemical evaluation of mouse and rat kidneys with lectin-horseradish peroxidase conjugates

Abstract: Paraffin sections of mouse and rat kidney were stained with a battery of ten lectin-horseradish peroxidase conjugates and lectin binding was correlated with the ultrastructural distribution of periodate-reactive sugar residues as determined by the periodic acid-thiocarbohydrazide-silver proteinate technique. Various segments of the uriniferous tubule in both species showed differential affinity for labelled lectins. Significant differences were also evident between comparable tubular segments in mouse and rat kidneys. Neutral glycoconjugates containing terminal beta-galactose and terminal alpha-N-acetylgalactosamine were prevalent on the luminal surface of the proximal convoluted tubule in the rat, but alpha-N-acetylgalactosamine was absent in this site in the mouse. In both species, terminal N-acetylglucosamine was abundant in the brush border of proximal straight tubules but absent in proximal convolutions. Fucose was demonstrated in both proximal and distal segments of mouse kidney tubules but only in the distal nephron and collecting ducts in the rat. Lectin staining revealed striking heterogeneity in the structure and distribution of cellular glycoconjugates. Such cellular heterogeneity was previously unrecognizable with earlier histochemical methods. The marked cellular heterogeneity observed with several lectin-conjugates in distal convoluted tubules and collecting ducts of both species raises a prospect that lectins can provide specific markers for intercalated and principal cells in the mammalian kidney. Glycoconjugates containing terminal sialic acid and penultimate beta-galactose were present on vascular endothelium in both rodent kidneys, as were terminal alpha-galactose residues; but both species lacked reactivity for Ulex europeus I lectin in contrast to human vascular endothelial cells. The constant binding pattern of lectin conjugates allows convenient and precise differentiation of renal tubular segments and should prove valuable in the study of changes in kidney morphology promoted by experimental manipulation or pathologic changes.

Adolescent chest pain: a prospective study.

Abstract: One hundred adolescents with chest pain were prospectively analyzed to determine the etiology, functional consequences, and illness attributions of patients seen in a general pediatric clinic. The typical patient had frequent pain (63% had two or more episodes weekly) of moderate duration (51% of the pain lasted longer than six minutes) that had been occurring for many months (36% had pain occurring longer than 6 months). Stressful events, such as a death in the family, major illness, an accident, family separations, and school changes occurred in 31% of patients. The most frequently diagnosed condition was musculoskeletal problems (31%) including costochondritis (14%), chest wall syndrome (13%), skeletal trauma (2%), and ribcage anomalies (2%). Hyperventilation accounted for 20% of diagnoses and 5% had breast-related problems. Thirty-nine percent of patients had pain not readily classifiable. Serious underlying illness was a rare cause of chest pain, although several patients had associated organic disease not responsible for their chest pain. More than two thirds of patients restricted physical activities; more than 40% were absent from school. When patients were questioned about their understanding of their illness, 44% were afraid that they were experiencing a heart attack, 12% worried about heart disease, and 12% feared cancer. Chest pain is a prevalent problem that is usually benign but is commonly misunderstood and causes considerable dysfunction and anxiety in adolescents.

Stereoselective binding of propranolol to human plasma, α1-acid glycoprotein, and albumin

Abstract: Our aim was to determine possible stereoselectivity in the plasma binding of propranolol. Equilibrium dialysis with plasma from seven healthy subjects and a deuterium-labeled pseudoracemate of propranolol was used. Plasma binding of the propranolol enantiomers differed with the unbound fraction of (-)-propranolol (22 +/- 2%; mean +/- SE) being smaller than that of (+)-propranolol (25.3 +/- 1.9%). The (-)/(+)-propranolol ratio for the unbound fraction, a measure of the stereoselectivity, was 0.86 +/- 0.02. There was an inverse correlation between the unbound (-)/(+)-propranolol ratio in individual subjects and overall binding of (+/-)-propranolol, indicating greater stereoselectivity at higher total binding. To assess the site of the stereoselective binding to plasma proteins, the binding of (+)- and (-)-propranolol to human alpha 1-acid glycoprotein (AGP) and human serum albumin (HSA) was examined. The binding to AGP was stereoselective for (-)-propranolol with a (-)/(+)-propranolol ratio for the unbound fraction of 0.79 +/- 0.01, whereas (+)-propranolol was bound to a greater extent to HSA with a (-)/(+)-propranolol ratio for the unbound fraction of 1.07 +/- 0.01. Although these results demonstrate opposite stereoselectivity in the binding of (+)- and (-)-propranolol to AGP and HSA, the stereoselective binding of (-)-propranolol to AGP predominates in plasma. This stereoselective plasma binding of the (-)-enantiomer of propranolol could limit the access of this more active enantiomer to beta-receptors or other active sites. The uptake of propranolol by red blood cells was not stereoselective.

Endocrine function following complex partial seizures.

Abstract: Previous studies have demonstrated hyperprolactinemia following generalized tonic-clonic seizures and after electroconvulsive therapy. We found transient hyperprolactinemia following complex partial seizures but little change in serum gonadotropins, thyroid-stimulating hormone, growth hormone, or cortisol. Serum prolactin was invariably normal interictally. Postictal elevation of serum prolactin may represent a biochemical marker of complex partial seizures, and it offers a potential pathogenic mechanism for the sexual dysfunction that often complicates temporal lobe epilepsy.

Linkage between surface immunoglobulin and cytoskeleton of B lymphocytes may involve Gc protein

Abstract: The membrane immunoglobulin (MIg) of B lymphocytes is thought to have an important role in antigen recognition and cellular activation1,2. In common with many membrane glycoproteins, MIg moves extensively in the lipid bilayer, and after binding of specific antisera displays lateral mobility with patch and cap formation3,4. This phenomenon appears to involve the cytoskeleton, particularly the actin that is present in the cell membrane of B lymphocytes5 and aggregates beneath capped immunoglobulin6. Recently, it has been reported that the isolation of MIg results in co-purification of actin and an unknown protein of molecular weight (MW) ∼56,000 (refs 7, 8). We now demonstrate that this component displays physicochemical and immunological properties indistinguishable from those of Gc (group-specific component)9. In addition, evidence is presented which suggests that this vitamin D3-binding protein is involved in the linkage between MIg and actin, and may therefore be important in signal transduction.

Molecular analysis of plasmids in epidemiologic investigation.

Abstract: The techniques themselves fall into two categories: indirect and direct techniques Indirect techniques include agarose gel electrophoresis and restriction endonuclease analysis Electrophoresis of plasmids in an agarose gel provides a fairly accurate estimate of the size of a plasmid molecule [3] Re- striction endonucleases are bacterial enzymes that cleave double-stranded DNA at specific recognition sites to generate a series of plasmid fragments [4] The number and sizes of these fragments depend upon the number and location of specific recognition sites present in the plasmid molecule If two plasmids are of the same size and yield identical patterns of fragments on restriction endonuclease analysis, especially if two or more restriction enzymes are used, they may be assumed to be identical or nearly so Conversely, two plasmids of the same size may have entirely different base sequences; this can be recognized by the different fragment patterns generated by a restriction endonuclease Finally, two plasmids may be quite different in size but possess one or more homologous regions of DNA; an intimation of this may be obtained by finding shared fragments on restriction endonuclease analysis Direct techniques involve hybridization of DNA

Development of fetal retina, tectum, and cortex transplanted to the superior colliculus of adult rats.

Abstract: Earlier studies showed that embryonic retina, cortex, or tectum transplanted adjacent to the superior colliculus of newborn host rats differentiated many of the histological features appropriate for the donor region and developed interconnections with the host nervous system. In the study presented here, the same regions were transplanted to the brain of adult host rats and the development of these transplants was compared to those into newborn hosts. Retina, rostral tectum, or occipital cortex was dissected from donor rat embryos on gestational day 14 or 15. A portion of cortex was aspirated in 2-;menth-old host rats to expose the right superior colliculus, and one of the donor tissues was placed adjacent to the colliculus in each host. Two to 4 months after transplantation, transplant histology and neuronal interconnections between the transplant and host nervous system were studied by using Nissl and neurofibrillar stains and 3H-proline and HRP tract tracing techniques. Four main points can be drawn from these results. First, 80% of the transplants survived in adult hosts –a percentage comparable to that found in newborn hosts. Second, each of the types of tissues transplanted differentiated histological characteristics appropriate for its site of origin, although the degree of differentiation was always much less than in transplants to newborns. Third, the transplants developed only relatively local projections into the host cortex and superior colliculus. This contrasts with the extensive projections found from the transplants into the brain of newborn hosts. Fourth, no definitive projections from the host retina or brain were identified to any of the transplants into adults, whereas both cortical and tectal transplants into newborns received projections from the host.

Neuronal composition and development in lamina 4C of monkey striate cortex.

Abstract: Lamina 4C (Lund, '73) of the monkey, Macaca nemestrina, visual striate cortex occupies a key position as a principal recipient zone of axons from the lateral geniculate nucleus (LGN). Synaptic maturation in lamina 4C is of particular interest since it involves a competitive interaction between thalamic axons for postsynaptic territory: an interaction which is strongly influenced by afferent activity (Hubel et al., '77). As an initial step toward understanding the normal process of synapse maturation in 4C, this study examines Golgi material to define the adult neuron populations of subdivisions 4C alpha (receiving afferents from magnocellular LGN) and 4C beta (receiving afferents from parvocellular LGN). Three groups of spine-bearing neurons are described--one relatively confined to either alpha or beta subdivision, the other two bridging the depth of 4C; four groups of smooth dendritic neurons interact with the spine-bearing population. Electron microscopy of normal and Golgi-impregnated tissue is used to define key features of synapse populations on these neurons. From embryonic day 159 through adulthood the smooth and spiny neurons occur in the same constant proportions in the neuropil (5% smooth, 95% spiny). Changes in the distribution of synapses on the spiny neurons are analyzed qualitatively; type 1 axon terminals (asymmetric apposition--round vesicles) shift from dendritic shafts to spine tips during maturation. Each spine is found to bear a type 1 contact at all ages; these results allow us to conclude that the figures of Boothe et al. ('79) on changes in spine populations during maturation can now be interpreted as changes in type 1 synapse populations. It is shown that type 2 synapses (symmetric appositions--pleomorphic vesicles) arise from axons of the smooth dendritic neurons. These synapses are found to increase in number on the spiny cell somata in early postnatal development, and this is followed by a decrease in number to the adult level.

Evidence for an orderly arrangement of optic axons within the optic nerves of the major nonmammalian vertebrate classes

Abstract: The pathways of selected optic axons were traced in representative urodele, anuran, teleost, reptile, and avian species by filling the fibers with HRP or by tracing, at the light and electron microscopic (EM) level, the degeneration caused by focal retinal or optic nerve lesions. In all species it was shown that fibers retain retinotopic neighborhood relationships throughout their transit of the optic nerve. Additionally, in anurans, it was found that a subset of large diameter, myelinated fibers take up a random arrangement in the nerve. It is argued that retinotopic fiber organisation is a reflection of contact guidance of axons during fiber outgrowth in the embryo and that this organisation could account for the arrival of fibers in orderly arrays at central nuclei during normal embryonic development.

Spine formation and maturation of type 1 synapses on spiny stellate neurons in primate visual cortex

Abstract: This study continues an investigation (Mates and Lund, '83a) of neuronal development in lamina 4C of macaque monkey striate visual cortex. The maturational history of the type 1 synaptic contacts on spine-bearing stellate neurons, which comprise 95% of the neurons of the lamina, is described. It is shown that type 1 contacts are initially found on the dendritic shafts; these contacts appear to be carried out on spine outgrowths. This leads to the adult condition where type 1 contacts are found only on the spine tips. A similar phenomenon has been reported for pyramidal neurons of the rat (reported during the course of this study by Miller and Peters, '81). In later maturation the spine and its type 1 contact may be lost; profiles found in the neuropil illustrate a process of shrinkage and detachment of both the type 1 axon terminals and postsynaptic dendritic spines in normal maturation. These findings provide an explanation for the marked increase and decrease in spine populations observed to occur on these neurons during normal maturation in an earlier study by Boothe et al. ('79).

Immunolocalization of carbonic anhydrase isozymes in rat and mouse salivary and exorbital lacrimal glands.

Abstract: Carbonic anhydrase (CA) isozyme I and isozyme II have been localized with the immunoperoxidase bridge method in cells of mouse and rat salivary glands and exorbital lacrimal glands. Immunostaining proved optimal in Carnoy fixed specimens for some sites and in Bouin fixed glands for other sites. Staining in mouse largely resembled that in rat glands, but minor species differences were observed. Serous acinar cells in the submandibular gland stained uniformly and exclusively for CA I. From 50 to 100% of the serous acinar cells in the parotid glands evidenced content of both CA I and CA II. A minor population of serous acinar cells in the mouse exorbital lacrimal gland stained for CA I and CA II, but these glands in the rat failed to stain. Immunostaining was observed in ducts in Bouin fixed glands. Some cells in striated ducts of submandibular and sublingual glands stained for CA I and CA II and other cells in these ducts were negative. Such cellular heterogeneity was also observed in excretory ducts of submandibular and sublingual glands. These findings thus demonstrate the presence of CA in two morphologically and functionally diverse cell populations in rodent salivary glands. Immunolocalization of the CA isozymes in serous acinar cells and intercalated duct cells, presumably packaged in secretory granules, implies a role for this enzyme in salivary secretions whereas localization of CA in striated and excretory ducts suggests their traditional function in fluid and electrolyte transport.

Purification of a calcium-activated neutral proteinase from bovine brain

Abstract: A calcium-activated neutral proteinase (CANP) resolved into three components has been partially purified from bovine brain. The method of isolation has resulted in 22,000, 7,100, and 8,000-fold purification for CANP I, II and III respectively. All three fractions require Ca2+ for activation. The characterization of the purified CANP I has shown that it is activated by 250 μM Ca2+ and the enzyme loses its activity when incubated in the presence of Ca2+ without substrate. Mg2+ is ineffective. The enzyme degrades neurofilament triplet proteins, tubulin and casein efficiently. The myelin basic protein is hydrolyzed after longer incubation. Bovine serum albumin and histones are unaffected. The enzyme is active at pH 5.5 to 9.0 with optimum between pH 7.5 and 8.5. It has a Km of 1.8×10−7 M for the 69,000 dalton neurofilament protein. The enzyme is inhibited by sulphydryl blocking reagents and also by EGTA, leupeptin and E-64c. The SDS-PAGE analysis of the enzyme fractions has shown a major band at 66–68,000 daltons and two minor bands at 60,000 and 48–50,000 daltons for CANP I; a major band at 48–50,000 daltons and a minor band at 30–32,000 daltons for CANP II and a predominant doublet at 30–32,000 daltons with a minor band at 48–50,000 daltons for CANP III. The degradation of neurofilament proteins suggests that the CANP(s) may be involved in the turnover of these proteins.

Developmental changes in the relationship between type 2 synapses and spiny neurons in the monkey visual cortex.

Abstract: This study continues an exploration of synaptic development in the primary visual cortex of the monkey (Macaca nemestrina). In a prior study (Mates and Lund, '83a), we observed that type 2 synapses on the cell bodies of spiny stellate neurons of lamina 4C appeared not only to increase in number during early postnatal development but also subsequently decreased during maturation. Using quantitative, stereological electron microscopic methods, we examined the maturation of this synapse population from embryonic day 159 to adult, on spiny stellate neurons of 4C alpha and beta and, for comparison, on pyramidal neurons in upper and lower lamina 6. Tissue was also taken for comparison from two animals reared to 8 weeks of age with binocular eyelid closure from birth. We confirmed that a marked increase and subsequent decrease occurred in this somal type 2 synapse population on both neuron populations. However, due to the infrequency of the smooth dendritic neurons (approximately 5% of the neuron population) giving rise to the type 2 contacts, and due to expansion of the neuropil during maturation increasing intercell distances against constant volume of the type 2 axon arbors, it is concluded that the decrease in type 2 somal synapses may represent a redistribution to dendrites rather than loss from the neuropil. Cells of lamina 4C beta (receiving input from the parvocellular lateral geniculate nucleus-LGN) show a slower initial accumulation of type 2 contacts compared to neurons of lamina 4C alpha (receiving input from magnocellular LGN), or to pyramidal neurons of lamina 6.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential Effects of Testosterone, Thyroxine, and Cortisol on Rat Submandibular Gland Versus Renal Kallikrein

Abstract: The effects of 17α-methyltestosterone (Tα), T4) or cortisol (F) on tissue kallikrein in the rat submandibular gland and renal cortex were measured. Castrated male or normal female Sprague-Dawley rats were treated with Tα or T4 for 2 weeks. In addition, F, Tα, or T4 was given to adrenalectomized female rats for 2 weeks. In the submandibular glands of male rats, castration resulted in a significant reduction of both kallikrein-like α-N-tosyl-Larginine methyl ester (Tos-Arg-OMe) esterase activity and immunoreactive kallikrein content. Treatment with Tα or administration of T4 significantly increased Tos-Arg-OMe esterase activity and immunoreactive kallikrein over that in the castrated rats receiving vehicle. Both the Tos-Arg-OMe esterase activity and kallikrein content of the submandibular glands of normal female rats were increased significantly by Tα or T4. However, Tα or T4 either significantly reduced or had no effect on renal Tos-Arg-OMe esterase activity or kallikrein content in castrated male or norma...

Evidence of increased Gc:actin complexes in pregnant serum: a possible result of trophoblast embolism.

Abstract: The molecular configuration of group-specific component Gc protein in sera from pregnant and nonpregnant individuals was compared by analytical isoelectric focusing and by print immunofixation in conjunction with known standards of Gc:actin and Gc:vitamin D3 complexes. These studies revealed that while complexes of Gc with actin and with vitamin D were detectable in small amounts in nonpregnant sera, much larger quantities of both types of complexes were consistently visualized in pregnancy. In addition, when actin was added to pregnant sera containing Gc:vitamin D3 complexes, a third anodal complex was revealed which presented the molecular configuration of actin: Gc: vitamin D3. These results demonstrate that Gc:actin complexes may be present under physiological circumstances in the circulation. Since large amounts of trophoblast enter the maternal circulation during both normal and abnormal human pregnancy, experiments were undertaken that showed that actin was released from isolated trophoblast membranes and also upon lysis of other viable cells under physiological conditions similar to those obtained in serum, and such actin complexed rapidly with Gc. Although the effects of this phenomenon upon the immunobiology of pregnancy are unknown, these findings are consistent with the concept that Gc protein may exert a “scavenger” function in mopping up actin released from damaged cells.