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PubMed2000

Sperm viability and morphology of two genetically diverse Merino lines.

Microscopically evaluated sperm parameters, as well as computer-aided sperm motility analysis (CASMA), were used to assess sperm quality and the effect of cryopreservation on ram semen obtained from two genetically diverse Merino lines. These lines were divergently selected on maternal ranking values for multiple rearing ability from the same base population since 1986. Replacements in the high (+) line were preferentially the progeny of ewes rearing >1 lamb per joining. Progeny of ewes rearing <1 lamb per joining was preferred as replacements in the low (-) line. Sperm quality, as assessed by percentages of live, abnormal and acrosome-intact spermatozoa as well as by motility, was independent (P < or = 0.20) of line, time of sampling and their interaction in ejaculated samples obtained from the eight rams used as sires in 1995. Sperm quality of frozen-thawed samples was adversely affected (P < or = 0.01) by cryopreservation and thawing at 35 degrees C for 30 s relative to fresh ejaculated samples. No consistent differences between lines were found in epididymal sperm samples obtained from 12 slaughtered rams (6 from each line). The adverse effect (P < or = 0.05) of cryopreservation and thawing at 35 degrees C for 30 s on sperm viability and motility was also demonstrated for these samples.

Animals↗
PubMed2005

Gene flow across linguistic boundaries in Native North American populations.

Cultural and linguistic groups are often expected to represent genetic populations. In this article, we tested the hypothesis that the hierarchical classification of languages proposed by J. Greenberg [(1987) Language in the Americas (Stanford Univ. Press, Stanford, CA)] also represents the genetic structure of Native North American populations. The genetic data are mtDNA sequences for 17 populations gleaned from literature sources and public databases. The hypothesis was rejected. Further analysis showed that departure of the genetic structure from the linguistic classification was pervasive and not due to an outlier population or a problematic language group. Therefore, Greenberg's language groups are at best an imperfect approximation to the genetic structure of these populations. Moreover, we show that the genetic structure among these Native North American populations departs significantly from the best-fitting hierarchical models. Analysis of median joining networks for mtDNA haplotypes provides strong evidence for gene flow across linguistic boundaries. In principle, the language of a population can be replaced more rapidly than its genes because language can be transmitted both vertically from parents to children and horizontally between unrelated people. However, languages are part of a cultural complex, and there may be strong pressure to maintain a language in place whereas genes are free to flow.

DNA, Mitochondrial↗
PubMed1986

Host cell-mediated selection of a mutant influenza A virus that has lost a complex oligosaccharide from the tip of the hemagglutinin.

During serial passage in Madin-Darby bovine kidney (MDBK) cells, a substrain of influenza virus A/WSN is lost from the population and is replaced by a mutant virus with altered host cell binding properties. This selection does not occur during growth in chicken embryo fibroblasts (CEF). It occurs during growth in MDBK cells because the parental virus produced by these cells has a dramatically reduced affinity for cellular receptors [Crecelius, D.M., Deom, C. M. & Schulze, I. T. (1984) Virology 139, 164-177]. We have now compared the hemagglutinin (HA) subunits, HA1 and HA2, of the parent and mutant viruses by NaDodSO4/PAGE and have found that when the viruses are grown in either host cell the HA1 subunit of the mutant is smaller than that of the parent virus. The nonglycosylated HAs, made in the presence of tunicamycin, have the same apparent molecular weight, indicating that the HA1 subunit of the mutant virus contains less carbohydrate than that of the parent. This reduction in carbohydrate content was observed with 11 independently derived mutants that had been selected by growth in MDBK cells. The nucleotide sequence of the HA gene of the parent and mutant viruses indicates that there are five potential glycosylation sites on the parent HA1 subunit and four on the mutant and that the mutation responsible for this difference is a single base change that eliminates the glycosylation site at amino acid 125 of the parent HA1 subunit. Treatment of the parent and mutant HAs from both cell sources with endo-beta-N-acetylglucosaminidases F and H showed that the HA1 of the parent virus has four complex and one high-mannose oligosaccharides, whereas that of the mutant virus has three complex and one high-mannose oligosaccharides. Thus, all of the potential sites on both HA1 subunits are glycosylated. We conclude that the oligosaccharide attached to amino acid 125 of the parent HA by MDBK cells can reduce the affinity of the virus for cellular receptors and that the mutant virus has a higher affinity than the parent because the mutant HA is not glycosylated at that site. Since amino acid 125 of the parent HA is glycosylated by both CEF and MDBK cells, we further conclude that the host-determined structure of the oligosaccharide at that site affects the affinity of the parent virus for cellular receptors and, thereby, determines whether the mutant virus will have a growth advantage.

Amino Acid Sequence↗
PubMed1988

Continuous synthesis of two protein-kinase-C-related proteins after down-regulation by phorbol esters.

The phorbol 12-myristate 13-acetate (PMA)-dependent down-regulation of immunoprecipitable protein kinase C was studied in human breast cancer cell lines that display different growth inhibitions toward the tumor promoter. PMA induces translocation of [35S]methionine-prelabeled cytosolic protein kinase C to membranes, followed by complete degradation of the enzyme (t1/2, 2 hr). PMA does not affect the protein kinase C synthesis; 20-80% of total protein kinase C of control cells was still immunoprecipitable as membrane-bound 74- and 80-kDa protein kinase C-related polypeptides if cells were allowed to incorporate [35S]methionine during PMA exposure for greater than 6 hr. These two proteins lack protein kinase activity and phorbol ester binding but reveal V8 peptide patterns identical to the active forms of protein kinase C (77/80 kDa) of PMA-untreated cells. The amounts of the immunoprecipitable membrane-bound 80-kDa protein kinase C-related polypeptide synthesized during the prolonged PMA treatment appear to inversely correlate with the extent of PMA-mediated growth inhibition of the respective human breast cancer cell line. These data suggest that after homologous down-regulation, functional protein kinase C (77/80 kDa) is replaced by a population of membrane-associated but enzymatically inactive protein kinase C-related polypeptides (74/80 kDa).

Breast Neoplasms↗
PubMed2005

Deconvolution of a complex target using DNA aptamers.

In vitro selection of single-stranded nucleic acid aptamers from large random sequence libraries is now a straightforward process particularly when screening with a single target molecule. These libraries contain considerable shape diversity as evident by the successful isolation of aptamers that bind with high affinity and specificity to chemically diverse targets. We propose that aptamer libraries contain sufficient shape diversity to allow deconvolution of a complex mixture of targets. Using unfractionated human plasma as our experimental model, we aim to develop methods to obtain aptamers against as many proteins as possible. To begin, it is critical that we understand how aptamer populations change with increasing rounds of in vitro selection when using complex mixtures. Our results show that sequence representation in the selected population changes dramatically with increasing rounds of selection. Certain aptamer families were apparent after only three selection rounds. Two additional cycles saw a decline in the relative abundance of these families and the emergence of yet another family that accounted for more than 60% of sequences in the pool. To overcome this population convergence, an aptamer-based target depletion method was developed, and the library screen was repeated. The previous dominant family effectively disappeared from the selected populations but was replaced by other aptamer families. Insights gained from these initial experiments are now being applied in the creation of second generation plasma protein screens and also to the analysis of other complex biological targets.

Aptamers, Nucleotide↗
PubMed1975

Control of bone resorption by hematopoietic tissue. The induction and reversal of congenital osteopetrosis in mice through use of bone marrow and splenic transplants.

The reciprocal transplantation of hematopoietic tissues was carried out on young, lethally irradiated mice of inbred, microphthalmic stock. The cell infusions prepared from the bone marrow or spleen of a normal littermate fully restored capacity to resorb bone and cartilage in the osteopetrotic recipients. Conversely, cell infusions prepared from the spleen of microphthalmic mice induced osteopetrosis in their irradiated, normal littermates. It is concluded that resorption of skeletal matrix is controlled by migratory cells, possibly osteoclastic progenitors, derived from the myelogenous tissues. No evidence was obtained to suggest that skeletal changes observed in the experimental animals were mediated by a graft-vs.-host reaction. The earliest skeletal changes in the experimental mice were detected 2 wk after onset which may represent the length or time required to replace the osteoclast population of the mouse.

Animals↗
PubMed1989

Blood carnitine status after orthotopic liver transplantation in patients with end-stage liver disease.

We determined the effects of orthotopic liver transplantation on plasma and red cell carnitine concentrations in patients with end-stage liver disease. Before transplantation, plasma and red cell carnitine were significantly elevated above normal. The partitioning factor (ratio of red cell carnitine to plasma carnitine) was four times greater than that observed in our reference population. After hepatic replacement, plasma and red cell carnitine approached normal levels within 6 mo. The partitioning factor, however, remained elevated at that time. These results indicate that 1) there is no evidence for carnitine deficiency in severe liver disease on the basis of carnitine concentrations in the plasma and red compartments and 2) altered partitioning of carnitine between plasma and red cells persists for greater than or equal to 6 mo after hepatic replacement.

Carnitine↗
PubMed2005

The susceptibility to growth-promoting antibiotics of Enterococcus faecium isolates from pigs and chickens in Europe.

OBJECTIVES: To establish the susceptibility of Enterococcus faecium isolates from pigs and chickens to antimicrobial growth promoters that either were or had been in use in the European Union. METHODS: Samples were taken at abattoirs in two successive years (mid-1998-mid-1999, year 1; mid-1999-mid-2000, year 2) from chickens (France, The Netherlands, Sweden, UK) and pigs (Denmark, The Netherlands, Spain, Sweden). E. faecium was isolated from faecal samples at national laboratories and sent to a central laboratory where MICs of avilamycin, avoparcin, bacitracin, flavophospholipol, spiramycin, tylosin and virginiamycin were determined. Microbiological breakpoints were allocated on the basis of MIC distributions, and comparison was made between host species, country of origin and year of sample. RESULTS: In total, 2567 isolates were obtained from chickens and 1742 from pigs. In all countries, resistance to avoparcin (banned in 1997) was uncommon, but resistance to bacitracin and flavophospholipol was common (and was probably largely intrinsic). The prevalence of resistance was similar in chicken and pig isolates, with the exception of avilamycin, to which resistance was commoner among chicken isolates. The removal of four compounds as growth promoters (bacitracin, spiramycin, tylosin, virginiamycin) between years 1 and 2 appeared to result in a significant decrease in resistance to three of them-spiramycin, tylosin and virginiamycin, with no change in resistance to bacitracin, but an increase in resistance to avilamycin (not discontinued). Associated resistance was shown between some of the compounds. CONCLUSIONS: Resistance prevalence declined rapidly following removal of growth promoters in pigs and chickens, suggesting that in the absence of selective pressure, a susceptible population began to replace phenotypically resistant strains. Associated resistance between different compounds, where seen, could have resulted from either shared resistance mechanisms or from carriage of resistance genes on the same plasmid. Multiresistance to streptogramins, macrolides and glycopeptides was rare.

Animals↗
PubMed1989

Percutaneous central venous catheterization in a pediatric intensive care unit: a survival analysis of complications.

We investigated the relationship between the duration of percutaneous central venous catheterization and the occurrence of catheter-related complications in critically ill children by survival analysis techniques. Data were collected prospectively and analyzed for infectious and noninfectious complications from 379 pediatric patients in whom central venous catheters had been placed in the pediatric ICU over a 45-month period. Cumulative survival rate analysis revealed a linear decrease in the number of complication-free catheters with time. The median duration of complication-free catheter survival was projected to be 23.3 days. The risk of catheter complication did not increase with increasing daily duration of catheter use as demonstrated by probability density function: catheter complication rates were similar on the first day after insertion (1.06 +/- 0.5%), the seventh day (4.27 +/- 1.6%), and the 24th day (2.48 +/- 2.4%). Therefore, in this population, routine catheter replacement would not be expected to lower the incidence of catheter-related complications, but may unnecessarily increase the number of insertion-related complications.

Adolescent↗
PubMed2003

Narrow time-window dual-point 18F-FDG PET for the diagnosis of thoracic malignancy.

Dual time-point imaging has been proposed as a means of improving the accuracy of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) for the diagnosis of malignant pulmonary nodules. The purpose of this study was to evaluate a dual time-point protocol that has a narrow time window between its initial and its delayed imaging sessions. All patients examined during a 16-month time period, either for the diagnosis of a radiographically indeterminate thoracic lesion or for the staging of non-small-cell carcinoma, were included in the study provided that they completed the dual-point protocol and had either biopsy evidence of malignancy, biopsy evidence of a benign condition involving the thoracic lesion of concern, or clinical and radiographic follow-up consistent with the absence of malignancy. The entire study population was further divided into a central subpopulation, whose index lesions were adjacent to or within the hilum or mediastinum, and a peripheral subpopulation, whose index lesions were non-central. The maximum standardized uptake value (SUV) was measured for each lesion, and various body surface areas (BSAs) and glucose corrections on the SUV were compared using discriminant analysis. BSA corrected SUVs for the initial (iSUV) and the delayed (dSUV) imaging sessions, along with their absolute difference (deltaSUV) and fractional difference (fSUV) were also compared using discriminant analysis and receiver operating characteristic (ROC) analysis. The study population consisted of 132 patients, of whom 81 had malignancy and 51 were classified as having a benign condition. Thirty-three index lesions were central and 99 were peripheral; 109 had visible uptake and 23 had such low uptake that they were not visible above background. The mean time (+/-SD) between initial and delayed imaging for the visible lesions was 31.1+/-9.4 min. With respect to the entire study population, the BSA replacement for body weight gave the best performance among the various SUV corrections examined. In addition, the BSA corrected delayed SUV (dSUV) gave a performance superior to either initial SUV (iSUV), absolute difference in SUV (deltaSUV) and fractional difference in SUV (fSUV) alone. Performance gains achieved by BSA correction and by dSUV appeared to derive primarily from the central subpopulation, thereby indicating that central lesions tend to behave differently to peripheral ones. For the central subpopulation, ROC analysis also demonstrated improved detection of malignancy from dual-point imaging. The best performance was achieved when the BSA corrected dSUV was at least 2.4, or when the fSUV showed at least a 5% increase from initial to delayed imaging. With the optimal combined dSUV/fSUV strategy, the area under the ROC curve was 0.99, as opposed to 0.96 for dSUV alone, or 0.93 for iSUV alone. The ability of 18F-FDG PET to discriminate between benign and malignant conditions of the central thorax can be improved by correcting the SUV for BSA and by increasing the 'incubation time' between 18F-FDG injection and imaging, or by performing narrow time-window dual-point imaging.

Adult↗
PubMed2007

Fungal colonization and infection in Boston keratoprosthesis.

PURPOSE: To determine the incidence of and risk factors for fungal keratitis and endophthalmitis in patients with a Boston keratoprosthesis (KPro) and to determine whether surveillance cultures were helpful in predicting fungal infection. METHODS: A retrospective chart review was performed of 182 patients (202 eyes) who received a type 1 (through cornea) or type 2 (through cornea and lid) KPro between March 1, 1990, and December 31, 2004, and who were followed for at least 1 month (range, 1 month to 13 years; mean, 2.84 years). There were 148 eyes with type 1 and 54 eyes with type 2. Beginning in late 1999, many eyes were given a prophylactic topical regimen containing vancomycin, and many eyes with type 1 KPro were given therapeutic contact lenses. Cases of fungal keratitis or endophthalmitis were analyzed. To determine the fungal colonization rate, 70 surveillance cultures of the ocular or lid surface around the KPro optic were obtained of 36 uninfected KPro eyes (35 patients) at random time-points over 1 year (August 2002 to July 2003). RESULTS: There were 4 definite and 1 probable fungal infections in 6893 patient-months of follow-up, or 0.009 fungal infections per patient-year. These included 3 cases of definite or probable Candida endophthalmitis (C. parapsilosis, C. glabrata, and C. albicans) and 2 cases of mold keratitis (Alternaria, Fusarium). The rate was higher in eyes receiving a vancomycin-containing topical prophylactic regimen than those with on a non-vancomycin regimen (5 cases/2774 person-months vs. 0 cases/4119 person-months; P = 0.011). In eyes with type 1 KPro, the rate was higher with therapeutic contact lens wear than without (4/1682 vs. 0/3115 person-months; P = 0.015). Surveillance cultures did not predict fungal infection, and none of the 6 surveillance eyes colonized with fungi (all Candida) developed a fungal infection. The prevalence of fungal colonization in KPro eyes had not changed since our 1996 surveillance study (11% vs. 10%, P > 0.05). CONCLUSION: Fungal infections in KPro eyes have appeared since we introduced broad-spectrum antibiotic prophylaxis and therapeutic contact lenses 5 years ago, but the infection rate remains very low in our mostly New England-based patient population. Cleaning or replacing the contact lens on a regular basis and prescribing a short course of topical amphotericin at the first visible signs of fungal colonization may prevent these infections.

Adult↗
PubMed1983

Influence of Langerhans cells on the survival of H-Y incompatible skin grafts in rats.

Evidence is presented that Langerhans cells (LCs) play an important role in the rejection of H-Y incompatible skin grafts in BN rats. Not only are small male trunk skin isografts much more likely to be rejected by BN females than similarly sized male foot pad, tail, and ear skin transplants, all of which possess fewer LCs than trunk skin, but the survival of male trunk skin grafts can be prolonged by replacing their LC population with allogeneic female cells.

Animals↗
PubMed1994

An atypical myeloproliferative disorder with t(8;13) (p11;q12): a third case.

A 43-year-old male presented with a myeloproliferative disorder with prominent lymphadenopathy. Examination of the bone marrow showed almost complete replacement by a population of cells with an acquired chromosomal translocation t(8;13)(p11;q12). There are two other case reports describing a similar clinical syndrome with t(8;13)(p11;q12) as the sole chromosomal aberration in bone marrow cells, suggesting a role for this translocation in the pathogenesis of this myeloproliferative disorder.

Adult↗
PubMed2005

Fire, rain and the selection of seeder and resprouter life-histories in fire-recruiting, woody plants.

Several Cape species of the genus Erica are known to present seeder and resprouter phenotypes, and this variation seems to have a genetic basis. Therefore, this genus provides ideal model systems for using to elucidate the evolution of nonsprouting or seeder and resprouter life-histories in woody, fire-recruiting plants. A simple simulation model was developed to identify, under life-history optimality, the ecological conditions (viz. rainfall conditions and fire frequency) that conferred a selective advantage to the seeder phenotype over the resprouter in a given Cape Erica species. The model illustrated that the seeder life-history was able to invade and replace a resprouter population only under a mild mediterranean climate, with short, moderate summer droughts. This simulation approach will contribute to a better understanding of the biogeographical pattern of seeder and resprouter lineages of one of the paradigmatic fynbos woody taxa throughout the Cape floristic region.

Biological Evolution↗
PubMed1995

First trimester fetal nuchal translucency: problems with screening the general population. 2.

OBJECTIVE: To investigate first trimester nuchal translucency > or = 3 mm as a screening test for aneuploidy in the normal pregnant population. DESIGN: A pilot observational study. SETTING: University College Hospital, London. SUBJECTS: One thousand one hundred and twenty-seven women had measurements of nuchal translucency at the time of their dating scan (8-13 weeks of gestation). RESULTS: Seventy fetuses (6%) had a nuchal translucency > or = 3 mm. Five karyotypically abnormal fetuses were identified by standard routine techniques (three trisomy 21, two trisomy 18), all in high risk mothers (> or = 39 years). Only two had nuchal translucency > or = 3 mm (one trisomy 21, one trisomy 18). CONCLUSIONS: Although nuchal translucency measurement is feasible and promising, there is at present insufficient data to warrant its introduction for screening of the general population, or to replace traditional second trimester screening.

Adult↗
PubMed1980

The response of ornithine decarboxylase during neuronal degeneration and regeneration in olfactory epithelium.

Mature olfactory neurons are continually replaced from a population of progenitor cells. Olfactory nerve section, bulbectomy, or treatment with certain chemicals induces degeneration of olfactory neurons followed in some cases by regeneration. Ornithine decarboxylase (ODC) activity was measured in mouse olfactory tissues as an indicator of cellular regeneration. ODC activity in olfactory tissue (0.2-0.4 nmol/mg protein/h) is 10-30 times higher than in a variety of other cerebral tissues. Within 3 h after unilateral olfactory nerve section, ODC activity in the epithelium declines to 50% of control followed by a slow return to basal activity by 6 days. In the same animals, ODC activity increases severalfold in bulb (1 day) with a gradual decline to normal (9 days). Except for an early transient increase, the effects of unilateral bulbectomy on epithelial ODC activity are similar to those seen after nerve section. The changes in ODC activity following intranasal irrigation with 10 mM-colchicine also closely mimic those seen after nerve section. The effects of intranasal irrigation on ODC activity with 0.5% Triton X-100 or 0.17 M-ZnSO4 are more complex. Thus, when the mature neuronal population is degenerating after surgery or chemical treatments, ODC activity decreases in the epithelium. The subsequent increase of ODC activity prior to reconstitution of the mature neuronal population probably reflects the regeneration mechanism of the olfactory epithelium. The increase of ODC activity in the olfactory bulb after nerve section is best interpreted as a cellular injury response. These alterations in ODC activity in olfactory tissues after chemical and surgical treatments constitute the earliest biochemical events observed in these tissues in response to cellular damage.

Aging↗
PubMed1978

Motility events of trichocyst insertion in Paramecium tetraurelia.

Following electroshock-induced extrusion of its inserted trichocysts, Paramecium tetraurelia rapidly begins replacement of the population of lost organelles. Light microscopy of the cortical insertion of new trichocysts reveals a series of characteristic motility activities. An uninserted trichocyst in the cyclotic flow of the cell appears to be "captured" and removed to the noncyclotic, subcortical regions. The trichocyst then makes a series of saltatory motions which apparently serve to transport it to the cortex, with proper orientation (tip first) for insertion. Trichocyst saltations end with either cortical insertion of the organelle, or return to cyclosis. If the trichocyst is inserted, it makes a series of unique pivoting movements around the motionless tip. This form of motility, termed "wobble," continues for a short period of time. After cessation of wobble, the insertion of the trichocyst is apparently complete, since no further motility is observed. With the aid of these observations it was possible to identify saltatory motility as the means for transporting trichocysts to the cortex for insertion, and also to observe a motility of unknown significance (wobble) apparently associated with the process of cortical insertion.

Animals↗
PubMed2003

Farmers and their languages: the first expansions.

The largest movements and replacements of human populations since the end of the Ice Ages resulted from the geographically uneven rise of food production around the world. The first farming societies thereby gained great advantages over hunter-gatherer societies. But most of those resulting shifts of populations and languages are complex, controversial, or both. We discuss the main complications and specific examples involving 15 language families. Further progress will depend on interdisciplinary research that combines archaeology, crop and livestock studies, physical anthropology, genetics, and linguistics.

Agriculture↗