Biomedical subjects

G L Nieder

Publications and source records attributed to G L Nieder.

At least 19 recordsLinked to original sources

PubMed2000

Going virtual with quicktime VR: new methods and standardized tools for interactive dynamic visualization of anatomical structures.

Continuing evolution of computer-based multimedia technologies has produced QuickTime, a multiplatform digital media standard that is supported by stand-alone commercial programs and World Wide Web browsers. While its core functions might be most commonly employed for production and delivery of conventional video programs (e.g., lecture videos), additional QuickTime VR "virtual reality" features can be used to produce photorealistic, interactive "non-linear movies" of anatomical structures ranging in size from microscopic through gross anatomic. But what is really included in QuickTime VR and how can it be easily used to produce novel and innovative visualizations for education and research? This tutorial introduces the QuickTime multimedia environment, its QuickTime VR extensions, basic linear and non-linear digital video technologies, image acquisition, and other specialized QuickTime VR production methods. Four separate practical applications are presented for light and electron microscopy, dissectable preserved specimens, and explorable functional anatomy in magnetic resonance cinegrams.

Anatomy, Cross-Sectional↗

PubMed2000

Using QuickTime virtual reality objects in computer-assisted instruction of gross anatomy: Yorick--the VR Skull.

QuickTime virtual reality (QTVR) is a software technology that creates, on a normal computer screen, the illusion of holding and turning a three-dimensional object. QTVR is a practical photo-realistic virtual reality technology that is easily implemented on any current personal computer or via the Internet with no special hardware requirements. Because of its ability to present dynamic photo-quality images, we reasoned that QTVR can provide a more realistic presentation of anatomic structure than two-dimensional atlas pictures and facilitate study of specimens outside the dissection lab. We created QTVR objects, using portions of the skull, and incorporated them into an instructional program for first-year medical students. To obtain images, the bones of the skull were mounted on a rotating table, and a digital camera was positioned on a swinging arm so that the focal point remained coincident with the rotational center of the object as the camera was panned through a vertical arc. Digital images were captured at intervals of 10 degrees rotation of the object (horizontal pan). The camera was then swung through an arc with additional horizontal pan sequences taken at 10 degrees intervals of vertical pan. The images were edited to place the object on a solid black background, then assembled into a linear QuickTime movie. The linear movie was processed to yield a QTVR object movie that can be manipulated on vertical and horizontal axes using the mouse. QTVR movies were incorporated into an interactive environment that provided labeling, links to text-based information and self-testing capabilities. This program, Yorick-the VR Skull, has been used in our first-year medical and graduate gross anatomy courses for the past two years. Results of student evaluation of the program indicate that this QTVR-based program is an effective learning tool that is well received by students.

Anatomy↗

PubMed1996

Matrix metalloproteinase expression during mouse peri-implantation development.

PROBLEM: The purpose of this study was to define the temporal expression and to quantitate the mRNA levels of collagenase, 72 kDa, 92 kDa, and membrane-type matrix metalloproteinase during the peri-implantation period of pregnancy in the mouse uterus. Embryonic expression of 72 kDa and 92 kDa matrix metalloproteinases, as well as interleukin 1 alpha, was also investigated. METHODS: Uterine matrix metalloproteinases were detected using gelatin substrate gel electrophoresis (zymography) and reverse-transcription polymerase chain reaction methodology was used to detect and quantitate different mRNA species in the mouse uterus and blastocyst. RESULTS: Collagenase, 72 kDa, and 92 kDa matrix metalloproteinases are developmentally regulated during the peri-implantation period of pregnancy, but membrane-type matrix metalloproteinase appears to be expressed constitutively. Matrix metalloproteinase mRNA levels have been quantitated and confirm the observed developmental expression patterns. Prominent expression of bot 92 kDa matrix metalloproteinase and interleukin 1 alpha was observed in blastocysts during outgrowth while weak expression of the 72 kDa matrix metalloproteinase was detected. CONCLUSIONS: The date provide evidence of matrix metalloproteinase expression in vivo and substantiate their potential role in tissue remodeling prior to and during blastocyst implantation. Expression of interleukin 1 alpha, 92 kDa, and 72 kDa matrix metalloproteinases suggests that these proteins are important for trophoblast invasion associated with implantation of the early embryo.

Animals↗

PubMed1995

Localization of NADPH diaphorase in the mouse uterus during the first half of pregnancy and during an artificially induced decidual cell reaction.

Uteri from non-pregnant and pregnant (Days 1-10) mice were examined for the presence of NADPH diaphorase (NADPH-d) activity by histochemical techniques. Macrophages positive for NADPH-d were observed in all uterine sections but appeared to migrate out of the implantation site and cluster in the mesometrium and interimplantation zones beginning on Day 4. NADPH-d activity was seen in the luminal and glandular epithelium and in several isolated fibers coursing through the myometrium. Many branches of the uterine artery also expressed activity, with the most intense staining in the vessels of the mesometrium. However, the most remarkable staining began on Day 6 within the primary decidual zone. When the stromal cells underwent decidualization, they began to show NADPH-d activity, with the pattern of activity matching the expanding area of decidualization. By Day 9 most of the decidual cell reaction had occurred and the mesometrial decidual staining began to decrease. However, the blood vessels and the cells surrounding the developing blood spaces continued to express activity, and heavy staining was evident within the antimesometrial decidua. No NADPH-d activity was seen in any of the trophoblast cells at any time, or in embryonic tissue, except on Day 8. NADPH-d has been used to identify nitric oxide (NO) synthase. Therefore, it may represent an NO-mediated paracrine control over decidual blood flow, myometrial quiescence, or immune response during pregnancy.

Animals↗

PubMed1992

Localization of c-fos-like proteins in the mouse endometrium during the peri-implantation period.

Fos, which collectively refers to protein products of the c-fos proto-oncogene family, was immunohistochemically localized in the mouse uterus to ascertain the effects of steroids on Fos expression in the mouse and to determine the course of Fos expression during normal pregnancy and pseudopregnancy. In ovariectomized mice, Fos was induced in luminal and glandular epithelium and an occasional stromal cell following treatment with 100 ng 17 beta-estradiol (E2). Priming with 2 mg progesterone (P4) for 3 days prior to the administration of 100 ng E2 or giving 100 ng E2 and 2 mg P4 concomitantly induced Fos in the luminal and glandular epithelium with enhanced staining in stromal cells. Priming with P4 before giving E2 had the added effect of inducing Fos at an earlier time point. Progesterone alone failed to induce Fos in any cell type in the uteri of ovariectomized animals. On Days 1 and 2 of pregnancy and pseudopregnancy, Fos was detected in the luminal and glandular epithelium and in the stroma. Staining was decreased by Day 3 and was not detectable by the morning of Day 4. No further staining for Fos was found during subsequent days of pseudopregnancy. On the afternoon of Day 4 of pregnancy, Fos was detected in the epithelium and the antimesometrial stroma. On the morning of Day 5, implantation sites and non-site areas were distinguishable, with Fos present in luminal epithelium and antimesometrial stroma in sites, and in just the luminal epithelium in non-sites. Fos remained in the epithelium of non-sites through Day 7 of pregnancy. In sites on the afternoon of Day 5, staining was found in the luminal epithelium and primary decidual zone. On Day 6, staining was found in the secondary decidual zone, but was absent from the primary zone and epithelium. On Day 7, Fos was also detected in the embryonic trophoblast giant cells and the ectoplacental cone. These results demonstrate that E2 and P4 modulate Fos in the mouse endometrium and that Fos is induced during implantation. Significantly, the embryo appears to induce Fos expression on the afternoon of Day 4, while it is still encased in the zona pellucida.

Amino Acid Sequence↗

PubMed1991

Initiation of placental lactogen-I production by blastocysts growing on a two-dimensional surface and in hanging drops.

The mouse blastocyst undergoes a program of protein secretion during the perimplantation period including the initial production of placental lactogen-I (mPL-I) on day 6 of pregnancy. Although blastocysts collected on day 5 also produce mPL-I when cultured to form outgrowths on plastic dishes, it was not known if embryos have an intrinsic ability to produce mPL-I during culture in vitro, or if a specific uterine influence is necessary. Earlier experiments also suggested that attachment of the trophoblast to a stable surface may be a prerequisite for synthesis of mPL-I. Both questions were addressed by examining mPL-I production by day 3 and day 4 embryos cultured either on a two-dimensional tissue culture dish surface or in hanging drops. The presence of intracellular mPL-I was assayed by immunohistochemistry, while the secreted hormone was detected by its known position in two-dimensional electrophoresis gels. These experiments demonstrated that these earlier stage embryos do have an intrinsic program for mPL-I production which proceeds in vitro under various culture conditions. Synthesis of mPL-I occurred in embryos suspended in hanging drops as well as in those spreading on a solid two-dimensional surface, thus showing that adhesion to a surface is not required for production of this hormone. Although some mPL-I synthesis was seen in embryos cultured in medium containing BSA as the sole macromolecule, the inclusion of fibronectin either in dishes, where it supports attachment, or in the hanging drop system stimulated mPL-I secretion. Serum supplementation in both culture systems further increased growth and differentiation of the embryo, as well as mPL-I secretion, compared to fibronectin supplementation.

Animals↗

PubMed1990

Early embryo development in the Siberian hamster (Phodopus sungorus).

Development of preimplantation embryos of the Siberian hamster (Phodopus sungorus) in vivo and in vitro was examined. The timing of early development in vivo was found to be slower than that reported for the golden hamster. Progression through the cleavage stages, cavitation, and hatching from the zona pellucida occurred later, with blastocyst formation beginning on the afternoon of day 4 and uterine attachment occurring early on day 5. In vitro, morulae, and early blastocysts collected on day 4 and cultured in serum-containing medium formed expanded blastocysts and some began to hatch from the zona pellucida. With extended culture, blastocysts attached and formed trophoblast outgrowths. Outgrowth was characterized by an initial migration of small cells from the blastocyst, followed by formation of a sheet of trophoblast giant cells. Differences in the morphology of outgrowth between the hamster and mouse suggest that further comparative studies with the Siberian hamster may be useful.

Animals↗

PubMed1990

Protein secretion by the mouse trophoblast during attachment and outgrowth in vitro.

Protein secretion from mouse blastocysts undergoing attachment and trophoblast outgrowth in vitro was assessed. When Day 5 blastocysts were cultured in serum-containing medium, secretion of several 'attachment-associated' proteins (PAS) was initiated within 24 h, coincident with attachment and outgrowth. Those proteins characteristic of the pre-attachment blastocyst disappeared or made-up only a small portion of the secretions once attachment began. The major secreted protein from attached embryos, PA1, is a 35,000-45,000 Mr acidic glycoprotein with multiple isoelectric forms. PA2, a group of basic 40,000 Mr proteins and PA3 a group of 72,000 Mr proteins were also produced during outgrowth. PAS were secreted during outgrowth on fibronectin-coated plastic in serum-free medium, but not by blastocysts held in a non-attachment state during culture in serum-free medium on uncoated plastic. In pre-attachment blastocysts, secreted proteins were produced by trophoblast vesicles, but not by isolated inner cell masses. Both trophoblast vesicles growing out in vitro and surgically isolated trophoblast from spreading blastocysts had secreted protein patterns qualitatively similar to those of intact blastocyst outgrowths. The results indicate that development of trophoblast protein secretion continues through the period of outgrowth and giant cell transformation. These changes are apparently dependent on attachment of the blastocyst to a suitable substrate, but not dependent on any other serum influence.

Animals↗

PubMed1990

Production of mouse placental lactogen-I by trophoblast giant cells in utero and in vitro.

Mouse placental lactogen-I (mPL-I) is the earliest appearing member of the PRL-GH family of placental hormones. Using immunological techniques, we have localized mPL-I both in utero and in vitro to trophoblast giant cells. Detectable amounts of mPL-I were first seen by immunohistochemistry on day 6 of gestation in the mural trophoblast. On day 7 giant cells of the ectoplacental cone also contained mPL-I, and on day 10 giant cells adjacent to both the decidua basalis and decidua capsularis stained positive. By day 12 however, all intra- and extraembryonic tissues were negative. The pattern of mPL-I staining in the placenta is consistent with its reported gestational serum profile. mPL-I was also present in trophoblast giant cells in vitro shortly after attachment and spreading of day 5 blastocysts. Analysis of conditioned medium from blastocyst outgrowths by immunoprecipitation and two-dimensional electrophoresis, and by immunoblotting, identified mPL-I as the major secretory product from the trophoblast, consisting of a group of acidic proteins of 30,000-45,000 Mr. The synthesis and secretion of mPL-I in vitro occurred in a serum-free medium suggesting that production of this hormone is part of an endogenous program of trophoblast differentiation.

Animals↗

PubMed1990

Interferon activity is not detected in blastocyst secretions and does not induce decidualization in mice.

Mouse trophoblast cells synthesized and secreted proteins during the peri-implantation period, some in the molecular size range of alpha interferons (IFN-alpha), known mediators of the maternal recognition of pregnancy in sheep and cows. However, conditioned media samples containing secreted proteins from Day-5 mouse blastocysts or from trophoblast outgrowths did not contain detectable levels of antiviral activity indicative of IFN. In addition, it was not possible to induce a decidual reaction in suitably sensitized uteri with intraluminal instillation of IFN-alpha. The results indicate that IFNs are probably not involved in the maternal recognition of pregnancy at the time of implantation in the mouse.

Animals↗

PubMed1989

Analysis of proteins secreted by mouse embryos developing in vivo and in vitro.

Proteins secreted by mouse blastocysts developing in vitro were compared to these from blastocysts developing in utero to determine if a simple medium supporting blastocyst development also supports secreted protein expression. In-vivo embryos were collected on days 3, 4, or 5 of pregnancy and incubated in 35S-methionine to produce conditioned medium containing released, labeled proteins. Embryos for culture were collected on day 3 and after 48 or 72 h labeled conditioned medium was produced. Labeled proteins were separated by two-dimensional electrophoresis and compared using a digital image analysis system. Day 3 embryos did not release proteins in detectable amounts, although synthesis of intracellular proteins was substantial. Day-4 and -5 blastocysts released proteins in increasing amount and complexity, consistent with previous results. When day-3 embryos were cultured in medium containing 4 mg/ml BSA for 48 h, secreted protein patterns were similar but not identical to those of day-5 uterine blastocysts. Although most of the proteins produced by uterine blastocysts were secreted by cultured embryos, differences were found in the relative quantities of certain proteins. Neither crystallized BSA nor polyvinyl alcohol at 4 mg/ml supported development of protein secretion as well as the crude fraction-V BSA. Blastocysts restricted to the oviduct also exhibited quantitative differences in protein secretion patterns compared to uterine blastocysts. Thus, although blastocyst development and the expression of many secreted proteins are supported outside the uterus, the full pattern of secretion characteristic of the peri-implantation embryo may be dependent on specific uterine influences.

Animals↗

PubMed1988

Effect of deciduogenic stimuli on protein secretion by the mouse uterus.

Instillation of oil into progesterone-primed, oestrogen-sensitized uteri of mice resulted in secretion patterns which were similar, but not identical, to those found on Day 5 of pregnancy. Stimulus-dependent responses common to pregnancy and the experimental decidual cell reaction included an early but transient increase in a 40,000 Mr basic protein and decreases in two other proteins. Some of the characteristic changes were also found after oil instillation in the progesterone-maintained 'non-receptive' uterus, even though subsequent decidualization did not occur. Instillation of cholera toxin, another deciduogenic substance, also resulted in patterns similar to those of pregnancy, including an increased secretion of a 25,000 Mr acidic protein which was only minimally produced during the oil-induced decidual cell reaction.

Animals↗

PubMed1987

Synthesis and secretion of stage-specific proteins by peri-implantation mouse embryos.

Blastocysts were recovered from intact mice at various times on the fourth and fifth days of pregnancy and incubated in vitro with 35S-methionine. Labeled proteins synthesized by the embryos and secreted into the medium were separated in two-dimensions on polyacrylamide gels by electrophoresis and localized by fluorography. The array of proteins synthesized and secreted by late stage blastocysts was found to be qualitatively and quantitatively different from those released by embryos at earlier stages of development. Similar changes were also observed in secreted proteins when delayed-implanting embryos were reactivated after an injection of estrogen. Furthermore, there was a temporal correlation between the appearance of certain proteins secreted by the embryos and changes in specific proteins synthesized and released by the uterus. It is suggested that these various secreted proteins constitute a signal-response mechanism that is important for the process of embryo implantation in mice.

Animals↗

PubMed1987

Uterine and oviducal protein secretion during early pregnancy in the mouse.

Changes in the protein composition of the embryo's environment during early development were studied by analysis of proteins synthesized and secreted by oviducal and uterine explants on Days 1-6 of pregnancy. Although secretions from ampullar and isthmic oviduct and uterus contained many proteins in common, each area also produced its own characteristic proteins. In the uterus, changes in the secretion pattern were found during the peri-implantation period, including both increases and decreases in particular proteins which appear to be dependent on the presence of embryos. Embryo-induced effects on uterine secretion began between 09:00 h of Day 4 and 09:00 h of Day 5. Oviducal secretions exhibited many of the embryo-dependent proteins found in the uterus, but the expression of these proteins did not appear to be influenced by the presence of embryos on Day 1 or Day 3. The characteristic pattern of secreted protein expression by each portion of the reproductive tract may reflect the specialization of each area for certain developmental events.

Animals↗

PubMed1985

Catecholamine, adenosine triphosphate, and P-creatine levels in decapitated whole mouse brain.

The levels of norepinephrine, epinephrine, dopamine, adenosine triphosphate, and P-creatine were measured in whole mouse brain collected under two conditions: 1) the decapitated head was immediately plunged into liquid nitrogen (nonanoxic tissue); or 2) the tissue was allowed to remain anoxic before the quick-freezing procedure. The substrate levels were significantly decreased in brain anoxic for only 30 sec. The catecholamine levels in nonanoxic mouse brain appear to be higher than levels previously reported in brains collected with microwave irradiation or by decapitation with rapid dissection of tissue before it was frozen.

Adenosine Triphosphate↗

PubMed1985

Effects of metabolic substrates and ionic environment on in-vitro activation of delayed implanting mouse blastocysts.

The possibility that the embryonic diapause associated with delayed implantation in mice is maintained by limitation of an essential amino acid, energy substrate or concentration of ions was examined by comparing the rates of DNA synthesis in delayed implanting embryos that were 'reactivated' by incubation in 'complete' medium or in one of several specially formulated 'deficient' media. It was found, in agreement with earlier observations, that an increase in the rate of DNA synthesis could be detected within 12 h and continued through 72 h in complete medium. An identical pattern was found when embryos were incubated in medium deficient in amino acids and vitamins. Similar patterns of activation were observed in the absence of all metabolizable substrates, a drastically reduced concentration of Na+, and even in a medium consisting only of 25 mM-bicarbonate buffer, NaCl and KCl. The embryos incubated in the more drastically deficient media appeared to be damaged after 18-24 h. Nevertheless, the observation that the rate of DNA synthesis did not remain depressed suggests that such deficiencies are not the means by which embryonic dormancy is maintained in utero.

Animals↗

PubMed1984

Regulation of glycolysis in the mouse blastocyst during delayed implantation.

The rate of oxidation of glucose is reduced in mouse embryos in the prolonged free living phase associated with delayed implantation and increases when the embryos are reactivated by estrogen. To determine how these changes in metabolism are regulated, several aspects of glucose metabolism were evaluated in dormant and reactivated blastocysts: 1) Embryos were exposed to 14C-pyruvate in vitro and evolved 14CO2 was measured. It was found that the rate of production of CO2 was equal in the two types of blastocysts, suggesting that aerobic pathways are fully functional during delayed implantation. 2) Production of lactate in the presence of O2 was measured and a decrease of 30% was found in delayed implanting embryos, suggesting that the overall regulatory mechanism for glucose metabolism resides in the glycolytic portion of the pathway. 3) Capacity for uptake and phosphorylation of glucose was evaluated using 3H-2-deoxyglucose and was found to be equal in the two types of embryos. 4) Total amounts of the rate-controlling enzymes for glycolysis (i.e., hexokinase and phosphofructokinase) in lysates of delayed and reactivated embryos were found to be equal, indicating that amounts of these enzymes are not limiting in delayed implantation. 5) Lactate production, measured under anaerobic conditions, was found to be equal, demonstrating that it is not the capacity for glycolysis but a difference in the degree of allosteric inhibition that is responsible for reduced glucose oxidation in delayed implantation. 6) Levels of ATP, ADP, and hexose-6-phosphates were found to be consistent with allosteric inhibition of the glycolytic pathway at phosphofructokinase during delay and a release of this inhibition with reactivation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerobiosis↗

PubMed1983

Pyruvate and lactate levels in oviducts of cycling, pregnant, and pseudopregnant mice.

Pyruvate and lactate were measured in oviducts during the first 5 days following ovulation in cycling, pregnant, and pseudopregnant mice, to determine how oviductal metabolism might change to promote the availability of these substrates to the early embryo. The postovulatory peak in ampullar pyruvate was most evident in the 12-h pregnant oviduct, 3.19 mmol . kg-1. This increase at +12 h was related to a decrease in lactate dehydrogenase (LDH) activity, compared to cycling animals, observed at this time. Although cycling animals showed a significant increase in isthmic pyruvate at +3 h, no change in isthmic pyruvate was observed in either mated group through the postovulatory period. Isthmic LDH activity was also unchanged in cycling or mated animals through this period. Ampullar lactate in both mated groups was elevated at 12 to 24 h after ovulation, a pattern similar to that seen in cycling animals. Isthmic lactate levels also increased after ovulation in all groups, but in the pregnant group the lactate remained elevated (25-28 mmol . kg-1) through 72 h, while concentrations in the cycling and pseudopregnant animals, returned to low levels (14-16 mmol . kg-1) by 48 h. The patterns of pyruvate and lactate, especially those in the pregnant animals, seem suited to providing these metabolites at levels near those required for optimal in vitro embryo growth. The +12 h ampullar pyruvate peak noted in mated animals implies a specific response to the mating stimulus. Prolongation of increased isthmic lactate levels only in pregnant animals suggests a response of the oviduct to the viable embryo.

Analysis of Variance↗