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Biomedical subjects

G B Anderson

Publications and source records attributed to G B Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1995

Birth of large calves that developed from in vitro-derived bovine embryos.

High birth weights were observed in calves that developed from bovine embryos produced by in vitro maturation (IVM) and in vitro fertilization (IVF) procedures. After IVM and IVF, embryos were either co-cultured in vitro with oviductal epithelial cells or transferred into the sheep oviduct for development to the blastocyst stage. Blastocysts were transferred to the reproductive tracts of recipient heifers and cows for development to term. Birth weights and gestation periods were compared between calves that developed from in vitro-derived embryos and calves born after artificial insemination (AI) of cows in the herd from which recipient females were selected. Gestation periods were not different among the groups (P > 0.05), but calves that developed from IVM/IVF-derived embryos co-cultured in vitro were larger at birth than calves born from IVM/IVF-derived embryos that developed into blastocysts in the sheep oviduct and calves born from AI (P < 0.001). Dystocia and calf mortality were associated with large calf size at birth. These data were collected from an experiment designed for other purposes, and confounding variables and small sample size could have influenced the observed differences in birth weights. Nevertheless, the extreme birth weights of some calves suggest that abnormal prenatal growth occurs in some IVM/IVF-derived bovine embryos and that conditions for co-culture to the blastocyst stage may exacerbate the problem.

Journal Article↗
PubMed1995

Presence of species-specific, monomorphic antigens on sheep and goat binucleate cells.

Immunocytochemical assays for sheep and goat species-specific, monomorphic antigens were developed utilizing polyclonal antisera from sheep and goats immunized by interspecific pregnancy. The assays were applied to cell isolates from sheep and goat fetal cotyledons collected from allogeneic pregnancies at Days 35, 40 and 120 of gestation. The isolates contained 7 to 48% binucleate cells (BNC). Using these assays, the sheep-specific antigen was detected on sheep cotyledonary cell isolates on all days of gestation tested (P < 0.001); the assay also detected the antigen on the BNC subset of the cotyledonary cell isolate population (P < 0.001). The caprine-specific antigen was shown to be present on cotyledonary cell isolates (P < 0.05), although the presence of the antigen could not be demonstrated with statistical confidence on goat BNC due to insufficient numbers of discernible cells. Binucleate cells contribute to the formation of the syncytial layer of the placenta by fusing with maternal epithelial cells and with the syncytium. The species-specific antigen (or antigens) is present on BNC at the appropriate time of gestation at which it (they) could play a role in the humoral immune response to interspecific and hybrid pregnancies observed in ewes and does.

Journal Article↗
PubMed1995

Risk of second aerodigestive cancers increases in patients who survive free of small-cell lung cancer for more than 2 years.

PURPOSE: Patients who survived small-cell lung cancer (SCLC) for more than 2 years were evaluated to determine the frequency and anatomic pattern of redevelopment of small-cell cancer and development of non-small-cell lung cancer (NSCLC) and aerodigestive cancers with the passage of time. PATIENTS AND METHODS: From April 1973 through December 1991, 578 patients with previously untreated SCLC were entered onto prospective therapeutic trials at the National Cancer Institute (NCI), Bethesda, MD. Sixty-two (11%) were cancer-free 2 years after initiation of therapy and were assessable for redevelopment of SCLC and development of NSCLC, and aerodigestive cancers. RESULTS: Twenty patients redeveloped SCLC 2.0 to 12.2 years after initiation of chemotherapy, of whom two patients were deemed to have a second primary small-cell cancer that involved the aerodigestive tract. Fifteen patients developed 16 cancers in the lung other than SCLC 3.4 to 14.9 years after initiation of therapy. Two developed other aerodigestive cancers that involved the larynx and lip. The risk of a NSCLC and aerodigestive cancer in these patients increased more than sixfold from 2% per patient per year during years 2 to 4 to 12.6% and 14.4%, respectively, after more than 10 years. The cumulative actuarial risk of a second primary NSCLC or aerodigestive cancer at 16 years is 69% and 72%, respectively. CONCLUSION: The increasing risk of second aerodigestive cancers with the passage of time is a mounting problem for patients cured of SCLC. Chemoprevention trials for these patients should be considered.

Adult↗
PubMed1995

The effect of mammary gland expression of human lysozyme on the properties of milk from transgenic mice.

Transgenic mice were used as model systems to evaluate the impact of human lysozyme expression in the mammary gland. We previously generated two lines of transgenic mice that express human lysozyme mRNA in the mammary gland under the tissue-specific and developmentally correct control of the bovine gene promoter for alpha s1-casein. Concentrations of human lysozyme protein in milk of transgenic mice varied from .25 to .71 micrograms/microliters of milk. Human lysozyme secreted into mouse milk retained its antimicrobial activity, as determined by a denaturing polyacrylamide gel activity assay. The physical and functional properties of the milk were also altered, because mouse milk containing human lysozyme had a 35% decrease in rennet clotting time, a smaller median micelle size (157 nm vs. 172 nm), and a 2.5- to 3-fold greater gel strength than control milk. From these results, we conclude that the use of transgenic animals producing lysozyme in the milk is feasible and potentially useful to the dairy industry.

Animals↗
PubMed1995

Effectiveness of an irrigating solution utilized during ultrasonic scaling.

The objective of this study was to determine whether removal of calculus was enhanced when ProSol PDS 22-4, an irrigating solution, was utilized during ultrasonic cleaning rather than a control (water). Thirty individuals with incipient-to-moderate generalized periodontitis who had not received previous root instrumentation were randomly divided into two equal groups. Baseline examinations included Plaque Index, Gingival Index, Retention Index, pocket depths, clinical attachment levels, bleeding on probing, and Discoloration Index. Immediately after treatment by ultrasonic scaling and the irrigation with either ProSol or water, and 2 weeks postscaling, the clinical parameters were reevaluated. Baseline mean Retention Index revealed no differences between experimental and control groups for any of the surfaces; however, immediately after instrumentation, significant differences were found between treatments in favor of the experimental condition.

Adult↗
PubMed1994

Delivery of a live calf after in vitro maturation and fertilization of oocytes obtained from ovaries removed from a moribund cow.

An aged Holstein cow of high genetic merit and economic value was determined to have a squamous cell carcinoma of the tarsus. Treatment was unsuccessful, as was an attempt at superovulation and embryo collection; thus, the owner elected euthanasia. On day 17 of the estrous cycle, the ovaries were removed via laparotomy and the cow was immediately euthanatized. Oocytes were aspirated from ovarian follicles and subjected to in vitro maturation and fertilization procedures. Seven morulae that developed in culture were transferred nonsurgically to 3 recipient females, resulting in birth of a full-term healthy male calf. In vitro maturation and fertilization procedures can be used to obtain offspring from valuable, terminally ill cows for which conventional embryo collection techniques have proven unsuccessful.

Animals↗
PubMed1994

Expression of human lysozyme mRNA in the mammary gland of transgenic mice.

Owing to its inherent antimicrobial effect and positive charge, the expression of human lysozyme in bovine milk could be beneficial by altering the overall microbial level and the functional and physical properties of the milk. We have used transgenic mice as model systems to evaluate the expression of human lysozyme containing fusion gene constructs in the mammary gland. Expression of human lysozyme was targeted to the mammary gland by using the 5' promoter elements of either the bovine beta (line B mice) or alpha s1 (line H mice) casein genes coupled to the cDNA for human lysozyme. Expression of human lysozyme mRNA was not found in mammary tissue from any of line B mice. Tissues were analysed from six lines of H mice and two, H6 and H5, were found to express human lysozyme mRNA in the mammary gland at 42% and 116%, respectively, of the levels of the endogenous mouse whey acidic protein gene. At peak lactation, female mice homozygous for the H5 and H6 transgene have approximately twice the amount of mRNA encoding human lysozyme as hemizygous animals. Expression levels of human lysozyme mRNA in the mammary gland at time points representing late pregnancy, early, peak and late lactation corresponded to the profile of casein gene expression. Human lysozyme mRNA expression was not observed in transgenic males, virgin females or in the kidney, liver, spleen or brain of lactating females. A very low level of expression of human lysozyme mRNA was observed in the salivary gland of line H5.

Animals↗
PubMed1994

Survival of porcine inner cell masses in culture and after injection into blastocysts.

Isolation of embryonic stem cells has been documented only in the mouse and perhaps the hamster and cow. We report results of experiments designed to determine the effect of age of porcine embryos (6 through 10 d after the first day of estrus) on isolation of cell lines with embryonic stem cell-like morphology. The capacity of fresh and short-term cultured inner cell mass (ICM) cells to differentiate into normal tissues after injection into blastocysts was also measured. Few Day-6 ICM survived in culture to the first passage onto fresh feeder cells, but cell lines with embryonic stem cell-like morphology developed from Day-7 through Day-10 ICM. Isolation of embryonic stem cell-like colonies was achieved at a higher frequency from ICM isolated from older embryos, but embryonic stem cell-like colonies from older embryos also tended to differentiate spontaneously in culture. Viable porcine chimeras were born after injection of fresh ICM into blastocysts that were transferred to recipients for development to term; no chimeras were born from blastocysts injected with ICM subjected to short-term (1 to 6 d) culture. Germ-cell chimerism was confirmed in one of the chimeras. These results document that undifferentiated cells can be removed from porcine blastocysts, transplanted to other embryos, and contribute to development of normal differentiated tissues, including germ cells. Cells with embryonic stem-like morphology can be isolated in culture from ICM at various embryonic ages, but ICM from young blastocysts (e.g., Day-7 embryos) yield embryonic stem cell-like colonies at lower frequency than do ICM from older blastocysts (e.g., Day-10 embryos).

Journal Article↗
PubMed1993

Sexing and detection of gene construct in microinjected bovine blastocysts using the polymerase chain reaction.

We present a polymerase chain reaction (PCR)-based procedure for rapid bovine embryo sexing and classifying embryos for the presence of exogenous DNA. Fourteen bovine blastocysts microinjected with gene construct DNA at the pronuclear stage were divided into quarters and subjected to amplification with construct-specific and sex gene-specific (ZFY/ZFX) primers in the same initial PCR reaction. Blastocysts carrying microinjected construct DNA could be identified by the presence of construct-specific PCR product in approximately 4 h. Approximately half of the microinjected and two of 16 non-microinjected blastocysts typed PCR-positive for the construct DNA. Owing to erroneous amplifications in the two non-microinjected control blastocysts, and the inability of the system to distinguish integrated from non-integrated copies of the microinjected construct, the number of construct-positive blastocysts determined in our assay most likely overestimates the number of true transgenic embryos. Nevertheless, using this assay, we were able to determine that approximately half of the microinjected embryos were negative for the transgene construct and thus could be eliminated from transfer to a recipient cow. Embryo sexing was achieved in less than 6 h by restriction fragment length polymorphism analysis of nested ZFY/ZFX PCR products reamplified from initial PCR reactions. In 11/14 microinjected blastocysts all sections assayed unambiguously as the same sex. In one embryo, only one section was analysed, while two other blastocysts showed some discrepancies of sexing results between the sections analysed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Cryopreservation of embryos as a means of germ plasm conservation in sheep.

Embryos were collected from 4 lines of Targhee sheep between 1986 and 1990. The lines were selected for preweaning growth rate (Lines DH and HW) or for multiple births (Line HT); Line C served as an unselected control group. Estrus was synchronized using fluorogestone acetate-impregnated vaginal pessaries, and ewes were superovulated with FSH. Embryos at the morula or blastocyst stage were surgically recovered from mature ewes at Days 5 to 6 and were frozen following morphological evaluation. The overall average number of freezable embryos per collection was 2.9, and did not differ significantly among years or among lines. Of the embryos collected between 1986 and 1988, 92 were transferred to 53 recipients in 1989, producing 53 lambs. Survival rates were 60.9 and 47.8%, respectively, for embryos evaluated as good and fair after thawing. Good-quality blastocysts yielded the highest survival rate (64.4%). Analyses indicated no significant effects of line, developmental stage or embryo evaluation on the incidence of lambing. It was concluded that embryos of morula or blastocyst stage can be successfully frozen for extended periods. The data on embryo yield and survival following cryopreservation were used to calculate numbers of donors needed to preserve and reconstitute a population of specified size.

Journal Article↗
PubMed1993

Tolerance of sheep-goat chimeras to their component cells.

Four sheep-goat chimeras with a goat or sheep sibling having an identical genotype to one of the two component species of cells were tested for tolerance through mixed lymphocyte response (MLR) and skin grafts. None of the four chimeras showed a response to its sib in MLR and three of the four accepted sib skin grafts. This demonstrates that the chimerism exhibited by these animals was sufficient to render the chimera tolerant to antigens expressed by the sib. Two of the four sibs showed positive responses to their chimeric sibs in MLR and two did not; one negative response was expected because the chimera's lymphocytes were essentially all the same species as the sib's. Chimeric skin grafts were partially accepted by two of the four sibs, suggesting the presence of both sheep and goat cells in the skin grafts derived from the chimeras. Two of the four sibs did not accept chimeric skin grafts, possibly due to lack of compatible cells in the graft. Neither differences between an allo- and xenoresponse in MLR nor time differences in the rejection of allo- and xenografts were observed.

Animals↗
PubMed1993

Reproductive cycles and pregnancy in interspecific sheep<==>goat chimaeras.

The objectives of the current study were to determine whether interspecific sheep<==>goat chimaeras exhibited reproductive cycles of their component species and were capable of maintaining ovine and caprine pregnancies to term. All chimaeras had oestrous cycles and several exhibited characteristics of both ewes and does, including short, 6-7-day cycles. Sixteen caprine pregnancies were confirmed in eight sheep<==>goat and one hybrid<==>sheep chimaera from 21 embryo transfers; of these, six appeared normal by ultrasonographic examination during Weeks 5 or 6, but none progressed beyond Week 8. Three apparent pseudopregnancies developed in two animals. In contrast, eight of 11 pregnancies in chimaeras resulted in term ovine offspring after transfer of ovine embryos or natural matings with rams. By comparison, interspecific (caprine or hybrid) pregnancies in ewes were lost in Week 4 (n = 8) or Weeks 5-6 (n = 2). First interspecific (ovine or hybrid) pregnancies in does were maintained longer (Weeks 6-12, n = 7) than second interspecific pregnancies (Weeks 4-5, n = 5) (P < 0.05) or interspecific pregnancies in ewes (P < 0.05). The results suggest that abnormal fetomaternal interactions during the early stages of implantation are responsible for termination of caprine pregnancies in the ovine or chimaeric uterus, whereas ovine conceptuses are able to implant successfully in the chimaeric uterus. All chimaeras were fertile, since each carried at least one ovine pregnancy to term following natural matings with rams.

Animals↗
PubMed1993

Effects of chimerism in sheep-goat concepti that developed from blastomere-aggregation embryos.

Chimeric sheep-goat pregnancies were established in 24 ewes and 29 does by transferring 251 embryos, prepared by the blastomere-aggregation technique, to 52 ewes and 61 does. Fifteen does experienced early pregnancy failure; however, term offspring were delivered by 24 ewes (17 lambs, 3 kids, 6 chimeras) and 14 does (6 lambs, 9 kids, 6 chimeras). (Fetal classifications were based on phenotype, red blood cell isozymes, and lymphocyte antigen expression). RIAs for ovine and caprine placental lactogen detected chimerism in the binucleate cell population of the trophoblast throughout the pregnancies of 2 ewes and 7 does; these pregnancies resulted in the birth of 12 healthy offspring. Histological examinations of intact placentomes from 2 of these recipients revealed a continuous cellular trophoblast apposed to a syncytium as in normal placentas. Chimerism was detected electrophoretically in the membranes of the placentas with binucleate cell chimerism and in 17/28 of the other placentas. Data collected on placental lactogen production, chimerism in the conceptus, and placental morphometry were examined with respect to the stages of the blastomeres aggregated to form the chimeric embryo and with respect to fetal status at delivery. For comparison, analogous data were collected on sheep-goat concepti that developed from embryos prepared by inner cell mass transplantation.

Animals↗
PubMed1993

Antibody response of ewes and does to chimeric sheep-goat pregnancy.

Antibody production was evaluated in 62 recipients of blastomere-aggregation sheep-goat embryos, including 23 multiparous ewes, 21 multiparous does, 16 primiparous does, and 2 virgin does. The reactivity of sera collected weekly after the embryo transfer surgery was compared to that of sera collected prior to the embryo transfer by means of 1) complement-dependent cytotoxicity tests against peripheral blood lymphocytes (PBLs) from the parents of the embryo(s) and from random-bred sheep and goats, 2) hemagglutination and hemolytic assays with red blood cells (RBCs) from the two sires of the embryo(s), and 3) assays with PBLs and RBCs following absorptions with RBCs and PBLs from the parents and offspring. Although cross-reactivity to ovine and caprine PBL antigens was present in the control sera of some recipients, xenogeneic immunization during pregnancy was detected in 20 of 30 recipients that experienced term pregnancy. The xenogeneic response involved the production of antibody that reacted with both PBLs and RBCs. Allogeneic responses to RBCs were not observed, but allogeneic responses to PBLs occurred frequently, beginning after the onset of the xenogeneic response in most recipients (98 +/- 28 vs. 57 +/- 15 days in ewes; 93 +/- 23 vs. 46 +/- 7 days in does; mean day of onset +/- SD). The onsets of the responses were examined in conjunction with data collected on fetal and placental chimerism to evaluate possible routes of immunization. The onsets of the allogeneic responses and the limited serum reactivity to third-party PBLs suggested that fetal lymphocytes leaking across the placenta immunized the recipients to parentally inherited polymorphic antigens. The xenogeneic responses were associated with placental chimerism and appeared to involve the recognition of a species-specific monomorphic antigen shared by PBLs and RBCs. Neither of the responses appeared to affect continuation of pregnancy to term.

Animals↗
PubMed1993

Tracheal occlusion from an intrathoracic stomach.

A patient presented with recurrent respiratory failure following esophagectomy. Systematic evaluation detected a previously unreported process causing this problem. Simple therapeutic measures were effective once the diagnosis was established.

Aged↗
PubMed1993

Failure of sheep-goat hybrid conceptuses to develop to term in sheep-goat chimaeras.

Six hybrid pregnancies were established: three in sheep-goat chimaeras, one in a sheep-(sheep-goat)hybrid chimaera and two in does. Pregnancies were monitored weekly by ultrasonography and peripheral concentrations of pregnancy specific protein B (PSPB) were measured. Placental development as detected by ultrasonography appeared to be slower in hybrid-in-goat pregnancies than in hybrid-in-chimaera pregnancies, although this difference was not reflected in PSPB concentrations. Time of fetal death could not be predicted from PSPB concentrations. Chimaeras appeared to carry hybrid pregnancies longer than ewes and does usually carry hybrid pregnancies, but none was carried to term.

Animals↗
PubMed1993

Guided tissue regeneration and bone grafts in the treatment of furcation defects.

The present study evaluated the effects of guided tissue regeneration (GTR), with and without demineralized freeze-dried cortical bone grafts, in the treatment of furcation defects in 4 female beagle dogs with naturally occurring periodontal disease. The root surfaces were thoroughly debrided. Four weeks later, full thickness facial and lingual mucoperiosteal flaps were reflected using inverse bevel incisions on both sides of the mandible involving the 2nd, 3rd, and 4th premolar, and the 1st molar teeth. Following debridement, notches were placed on the roots at the level of supporting bone. Test quadrants were randomly selected and furcations were filled with reconstituted, demineralized, freeze-dried human cortical bone grafts. Following bone grafting, all defects were covered with an expanded polytetrafluoroethylene (ePTFE) membrane, which was sutured with 4-0 sutures. Afterward, interproximal sutures were placed through the flaps, assuring the flaps covered the membranes completely. The contralateral side, serving as control, was treated by debridement only and application of ePTFE membrane. All membranes were removed 6 weeks after surgery. Dogs were sacrificed at 4 months after surgery. Both mesio-distal and bucco-lingual histologic sections were evaluated by descriptive histology. Linear measurements and surface area determination of the furcal tissues were carried out using the microscope attached to a digitizer. Twelve to 20 nonserial sections were made of the mid-buccal aspects of each root of each treated tooth. Half of these sections were stained with Harris' hematoxylin and eosin (H&E) and the other half stained with Mallory's trichrome stain.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗