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Biomedical subjects

R Kelly

Publications and source records attributed to R Kelly.

At least 73 records · Page 4Linked to original sources
PubMed1996

Effect of interval from fetal corticosteriod treatment to delivery on postnatal lung function of preterm lambs.

The effect of altering the interval from treatment to delivery on postnatal lung function of the preterm lamb is unknown. We treated groups of 8-10 singleton fetal sheep with 0.5 mg/kg betamethasone by fetal injection and evaluated postnatal lung function 40 min after preterm delivery at 123 days gestation 2 days after treatment or at 128 days gestation 2, 4, and 7 days after treatment relative to groups of 4-8 saline-injected control animals. At 123 days, betamethasone significantly improved arterial PCO2, dynamic thoracic compliance, and ventilatory efficiency index and doubled lung gas volume relative to a control group. Fetal treatment with betamethasone 2, 4, or 7 days before delivery at 128 days also improved these same indicators of lung function relative to controls, and the magnitude of the improvements was the same for all indicators and independent of treatment-to-delivery interval. Betamethasone suppressed the normal postnatal increase in plasma cortisol after 2 and 4 days of exposure but not after 7 days of exposure. Betamethasone also increased fetal and postnatal triiodothyronine concentrations after 2 days of exposure but not at 4 or 7 days of exposure. Although the hormone effects were transient, postnatal lung functional responses to betamethasone persisted over the 2- to 7-day interval from treatment to delivery.

Adrenal Cortex Hormones↗
PubMed1996

Activation of different myogenic pathways: myf-5 is induced by the neural tube and MyoD by the dorsal ectoderm in mouse paraxial mesoderm.

Newly formed somites or unsegmented paraxial mesoderm (UPM) have been cultured either in isolation or with adjacent structures to investigate the influence of these tissues on myogenic differentiation in mammals. The extent of differentiation was easily and accurately quantified by counting the number of beta-galactosidase-positive cells, since mesodermal tissues had been isolated from transgenic mice that carry the n-lacZ gene under the transcriptional control of a myosin light chain promoter, restricting expression to striated muscle. The results obtained showed that axial structures are necessary to promote differentiation of paraxial mesoderm, in agreement with previous observations. However, it also appeared that the influence of axial structures could be replaced by dorsolateral tissues, adjacent to the paraxial mesoderm. To elucidate which of these tissues exerts this positive effect, we cultured the paraxial mesoderm with a variety of adjacent structures, either adherent to the mesoderm or recombined in vitro. The results of these experiments indicated that the dorsal ectoderm exerts a positive influence on myogenesis but only if left in physical proximity to it. In contrast, lateral mesoderm delays the positive effect of the ectoderm (and has no effect on its own) suggesting that this tissue produces an inhibitory signal. To investigate whether axial structures and dorsal ectoderm induce myogenesis through common or separate pathways, we dissected the medial half of the unsegmented paraxial mesoderm and cultured it with the adjacent neural tube. We also cultured the lateral half of the unsegmented paraxial mesoderm with adjacent ectoderm. The induction of the myogenic regulatory factors myf-5 and MyoD was monitored by double staining of cultured cells with antibodies against MyoD and beta-galactosidase since the tissues were isolated from mouse embryos that carry n-lacZ targeted to the myf-5 gene, so that myf-5 expressing cells could be easily identified by either histochemical or immunocytochemical staining for beta-galactosidase. After 1 day in culture myogenic cells from the medial half expressed myf-5 but not MyoD, while myogenic cells from the lateral half expressed MyoD but not myf-5. By the next day in vitro, however, most myogenic cells expressed both gene products. These data suggest that the neural tube activates myogenesis in the medial half of paraxial mesoderm through a myf-5-dependent pathway, while the dorsal ectoderm activates myogenesis through a MyoD-dependent pathway. The possible developmental significance of these observations is discussed and a model of myogenic determination in mammals is proposed.

Animals↗
PubMed1996

Compartment syndromes of the hand.

We retrospectively reviewed the records of nineteen patients who had been managed with fasciotomy because of compartment syndrome of the hand. The patients were five months to sixty-seven years old and included ten adults and nine children. Seventeen patients were followed for an average of twenty-one months (range, one to fifty-eight months), one patient was lost to follow-up after discharge, and one patient died four days postoperatively. All of the patients had a tense, swollen hand and elevated pressure in at least one interosseous compartment. Eight patients also had a compartment syndrome of the forearm. The compartment syndromes developed after intravenous injections (eleven patients); after a gunshot wound, a crush injury, or a complication related to the use of an arterial line (two patients each); and after a complication related to an arthrodesis of the wrist or a crush injury due to prolonged pressure on the upper extremity secondary to a drug overdose (one patient each). Fifteen patients had an obtunded sensorium-either because of a serious illness or injury or secondary to prolonged anesthesia-when the compartment syndrome was recognized. In thirteen of these patients, including eight children and five adults, the compartment syndrome developed because of a complication related to the intravenous or intra-arterial administration of drugs. Carpal tunnel release and decompression of the involved compartments led to a satisfactory result for thirteen of the seventeen patients who were followed. The remaining four patients (including two children who had an amputation, one child who had impaired function of the hand secondary to brain damage, and one adult who had extensive involvement of the forearm and complete loss of function of the hand) had a poor result. All four of these patients had been obtunded when the compartment syndrome developed. The treating physician should maintain a high index of suspicion for a compartment syndrome of the hand when managing seriously ill, obtunded patients-particularly children-who are receiving multiple intravenous or intra-arterial injections.

Adolescent↗
PubMed1995

Lack of functional retinoblastoma protein mediates increased resistance to antimetabolites in human sarcoma cell lines.

Growth inhibition assays indicated that the IC50 values for methotrexate (MTX) and 5-fluorodeoxyuridine (FdUrd) in HS-18, a liposarcoma cell line lacking retinoblastoma protein (pRB), and SaOS-2, an osteosarcoma cell line with a truncated and nonfunctional pRB, were 10- to 12-fold and 4- to 11-fold higher, respectively, than for the HT-1080 (fibrosarcoma) cell line, which has wild-type pRB. These Rb-/- cell lines exhibited a 2- to 4-fold increase in both dihydrofolate reductase (DHFR) and thymidylate synthase (TS) enzyme activities as well as a 3- to 4-fold increase in mRNA levels for these enzymes compared to the HT-1080 (Rb+/+) cells. This increase in expression was not due to amplification of the DHFR and TS genes. Growth inhibition by MTX and FdUrd was increased and DHFR and TS activities and expression were correspondingly decreased in Rb transfectants of SaOS-2 cells. In contrast, there was no significant difference in growth inhibition among these cell lines for the nonantimetabolites VP-16, cisplatin, and doxorubicin. A gel mobility-shift assay showed that parental SaOS-2 cells had increased levels of free E2F compared to the Rb-reconstituted SaOS-2 cells. These results indicate that pRB defective cells may have decreased sensitivity to growth inhibition by target enzymes encoded by genes whose transcription is enhanced by E2F proteins and suggest mechanisms of interaction between cytotoxic agents and genes involved in cell cycle progression.

Antimetabolites, Antineoplastic↗
PubMed1995

Redistribution of synaptic vesicles and their proteins in temperature-sensitive shibire(ts1) mutant Drosophila.

From an extract of Drosophila melanogaster head homogenates, a membrane fraction can be isolated that has the same sedimentation properties as vertebrate synaptic vesicles and contains Drosophila synaptotagmin. The fraction disappears from homogenates of temperature-sensitive (ts) mutant shibire(ts1) (shi(ts1)) flies paralyzed by exposure to non-permissive temperatures, and reappears on return to permissive temperatures. Since reversible, temperature-dependent depletion of synaptic vesicles is known to occur in shibire(ts1) flies, we conclude that the fraction we have identified contains synaptic vesicles. We have examined the fate of synaptic vesicle membrane proteins in shibire flies at nonpermissive temperatures and found that all of these vesicle antigens are transferred to rapidly sedimenting membranes and codistribute with a plasma membrane marker by both glycerol velocity and metrizamide density sedimentation and by confocal microscopy. Three criteria were used to establish that other neuron-specific antigens--neuronal synaptobrevin and cysteine-string proteins--are legitimate components of synaptic vesicles: cosedimentation with Drosophila synaptotagmin, immunoadsorption, and disappearance of these antigens from the vesicle fractions in paralyzed shibire flies.

Amino Acid Sequence↗
PubMed1995

Myoblast differentiation during mammalian somitogenesis is dependent upon a community effect.

The differentiation potential of early mammalian myogenic cells was tested under clonal culture conditions. Cells were isolated from paraxial mesoderm and limb buds of transgenic mouse embryos at 9.5 days after conception and grown in culture at clonal density either on collagen-coated dishes or on various feeder cell layers. The transgene used contained a reporter gene encoding beta-galactosidase with a nuclear localization signal under the control of regulatory sequences from the gene for fast myosin light chain 3, so that beta-galactosidase staining indicated the presence of differentiated muscle cells. After 5 days in culture, the number and size of beta-galactosidase-positive (beta-gal+) clones were recorded. Cells isolated from somites I-V (the last five somites to have formed) or from unsegmented paraxial mesoderm did not give rise to any beta-gal+ clones. Cells isolated from somites VI-X or from the forelimb bud gave rise to beta-gal+ clones, but only on feeder cells. Cells from somites XI or older gave rise to beta-gal+ clones independently of the substrate. However, when cells isolated from unsegmented paraxial mesoderm or somites I-V were cultured with nontransgenic cells from the trunk (including neural tube and notochord), differentiation occurred on condition that the cells were in a three-dimensional aggregate, even though their specific position in the somite had been lost. By culturing explants ranging in size from 1 to < 100 cells in the presence of an inhibitor of cell division, we determined that a minimal number of 30-40 cells is required for mesodermal cells to differentiate.

Animals↗
PubMed1995

Regulatory, design, and analysis aspects of complex stability studies. US Food & Drug Administration.

Drug stability studies are expensive and time consuming. Multiple batches are studied to ensure that a product will consistently remain within specifications for its entire expiration dating period. Some of these studies involve the same drug products in similar packages or in multiple strengths. Application of sound statistical design principles can reduce the amount of testing required. We extend the principles stated in the Food & Drug Administration's 1987 publication Guideline for Submitting Documentation for the Stability of Human Drugs and Biologics to setting expiration dating periods for more complex situations.

Drug Packaging↗
PubMed1995

Postnatal lung function in preterm lambs: effects of a single exposure to betamethasone and thyroid hormones.

OBJECTIVE: We determined the effect of a single direct fetal injection of corticosteroid and thyroid hormones on postnatal pulmonary function in preterm lambs. STUDY DESIGN: Initially fetal sheep (126 days' gestation) randomly received saline solution, betamethasone (Celestone Soluspan, 0.5 mg/kg), betamethasone plus triiodothyronine (5 micrograms/kg), or betamethasone plus thyroxine (15 micrograms/kg) as a single injection. Forty-eight hours later (128 days' gestation) the fetuses were delivered and ventilated for 50 minutes. In a second protocol fetuses were delivered at 128 days' gestation, after only 24 hours of hormone exposure. RESULTS: Betamethasone treatment improved compliance nearly twofold after 24 or 48 hours of exposure. Efficiency of ventilation also improved after steroid therapy; this effect was augmented 48 hours after thyroxine exposure (but not triiodothyronine). No thyroxine effect was noted after 24 hours of exposure. Maximal lung volume increased by 80% after steroid treatment and doubled in response to combination betamethasone and thyroxine therapy. Alveolar pool sizes of saturated phosphatidylcholine and surfactant protein A were comparable for all groups exposed for 48 hours. CONCLUSIONS: A single fetal exposure to betamethasone improves postnatal pulmonary function after 24 or 48 hours. Addition of thyroxine (but not triiodothyronine) augments this effect at 48 hours.

Animals↗
PubMed1995

Myosin light chain 3F regulatory sequences confer regionalized cardiac and skeletal muscle expression in transgenic mice.

The myosin light chain IF/3F locus contains two independent promoters, MLC1F and MLC3F, which are differentially activated during skeletal muscle development. Transcription at this locus is regulated by a 3' skeletal muscle enhancer element, which directs correct temporal and tissue-specific expression from the MLC1F promoter in transgenic mice. To investigate the role of this enhancer in regulation of the MLC3F promoter in vivo, we have analyzed reporter gene expression in transgenic mice containing lacZ under transcriptional control of the mouse MLC3F promoter and 3' enhancer element. Our results show that these regulatory elements direct strong expression of lacZ in skeletal muscle; the transgene, however, is activated 4-5 d before the endogenous MLC3F promoter, at the time of initiation of MLC1F transcription. In adult mice, transgene activity is downregulated in muscles that have reduced contributions of type IIB fibers (soleus and diaphragm). The rostrocaudal positional gradient of transgene expression documented for MLC1F transgenic mice (Donoghue, M., J. P. Merlie, N. Rosenthal, and J. R. Sanes. 1991. Proc. Natl. Acad. Sci. USA. 88:5847-5851) is not seen in MLC3F transgenic mice. Although MLC3F was previously thought to be restricted to skeletal striated muscle, the MLC3F-lacZ transgene is expressed in cardiac muscle from 7.5 d of development in a spatially restricted manner in the atria and left ventricular compartments, suggesting that transcriptional differences exist between cardiomyocytes in left and right compartments of the heart. We show here that transgene-directed expression of the MLC3F promoter reflects low level expression of endogenous MLC3F transcripts in the mouse heart.

Animals↗
PubMed1995

The social dynamics of HIV transmission as reflected through discordant couples in rural Uganda.

OBJECTIVE: To describe the role of men and women as sources of HIV transmission and to estimate HIV incidence among discordant couples resident in diverse rural communities in Uganda. SETTING: Rakai, a rural district in Uganda, East Africa. METHODS: A population-based cohort study, which has been conducted as annual serological and behavioral surveys since 1989. Community clusters were stratified into trading centers on main roads, intermediate trading villages on secondary roads and agricultural villages off roads. In the 1990 survey round, serological data were available for 79 discordant and 411 concordant HIV-negative couples aged 13-49 years. The present analysis examines sex-specific seropositivity associated with place of residence and the incidence of seroconversion among discordant couples between 1990 and 1991. RESULTS: Seventy-nine discordant couples were followed; the HIV-positive partner was male in 44 couples (57%) and female in 35 couples (43%). There was marked variation in the sex of the seropositive partner by place of residence: women were the HIV-positive partner in 57% of couples from trading centers, 52% from intermediate villages, and 20% from agricultural communities (P < 0.008). Condom use was higher in discordant couples in which the man was the uninfected partner (17.1%) rather than the woman (9.5%). HIV-positive women, but not HIV-positive men, reported significantly more sexual partners and more genital ulcers than seronegative individuals of the same sex. Seroincidence rates among men and women in discordant relationship were 8.7 and 9.2 per 100 person-years (PY), respectively, which was much higher than in concordant seronegative couples (men, 0.82; women, 0.87 per 100 PY). CONCLUSIONS: In this Ugandan population, men are the predominant source of new infections in rural villages. Risk factors and preventive behaviors vary with the sex of the infected partner, and seroconversion rates are similar in both sexes.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Postnatal lung function in lambs after fetal hormone treatment. Effects of gestational age.

We previously found that a single dose of betamethasone in combination with thyroxine given by intramuscular injection to fetal sheep 48 h before preterm delivery at 128 d gestation improved postnatal lung function. We have now asked how the combination of 0.5 mg/kg betamethasone and 15 micrograms/kg T4 given by a single fetal intramuscular injection changes lung response 48 h after treatment at 121 and 135 d gestation. At 121 d gestation the fetal hormone treatment significantly improved postnatal lung function. Compliance increased by 55%, arterial PO2 increased from 39 to 215 mm Hg, PCO2 decreased from 109 to 79 mm Hg, and maximal lung volumes increased by 112%. The hormone treatment decreased the severity of the respiratory failure, although these very preterm lambs still had severe respiratory failure. At 135 d gestation, the fetal hormone treatment decreased the ventilatory pressure requirements that were needed to normalize PCO2 values from 30 to 21 cm H2O. Compliance increased by 40%, and maximal lung volumes increased by 33%. Alveolar or lung tissue, saturated phosphatidylcholine, or alveolar SP-A pool sizes did not change with hormone treatment at 135 d gestation. We conclude that fetal hormone treatment significantly improved postnatal lung function at both gestational ages, although the characteristics of the responses were different.

Animals↗
PubMed1995

Myogenic conversion of mammalian fibroblasts induced by differentiating muscle cells.

Somite-derived skeletal myoblasts are supposed to be the sole source of muscle fibre nuclei during pre- and postnatal development, but evidence is accumulating for unorthodox contributions to muscle fibre nuclei from other cell types. For example, in tissue culture, fibroblasts can fuse with dysgenic myoblasts and restore correct membrane function. We report here the results of a series of experiments investigating this phenomenon and its possible mechanism. 10T1/2 cells, infected with a replication defective retrovirus encoding the bacterial enzyme beta-galactosidase, fused to form beta-galactosidase positive, differentiated myotubes when cocultured with differentiating uninfected C2C12 or primary myogenic cells, but this did not occur when they were cocultured with other cells such as 3T3 fibroblasts or PC12 pheochromocytoma cells. Myogenic conversion ranged from 1 to 10% of the 10T1/2 cell population and required close cell interaction between the different cells types: it was not induced by conditioned medium or extracellular matrix deposited by C2C12 cells. Myogenic conversion was also observed in vivo, after injection of similarly infected 10T1/2 cells into regenerating muscle. Conversion was seen also after coculture of uninfected 10T1/2 cells with primary chick myoblasts, thus demonstrating that it was not dependent upon viral infection and that there is no species or class barrier in this phenomenon. Primary fibroblasts, isolated from different organs of transgenic mice carrying a Lac Z marker under the control of a muscle-specific promoter, restricting beta-galactosidase expression to striated muscle cells, also underwent myogenic conversion, when cocultured with C2C12 myoblasts.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1995

En bloc aortic resection for bulky metastatic germ cell tumors.

Between 1989 and 1993, 97 patients with stages B3 and/or C nonseminomatous germ cell tumors of the testes underwent induction chemotherapy followed by retroperitoneal lymph node dissection. Of these patients 6 (ages 22 to 41 years) had gross extension of tumor into the aortic adventitia at operation, which necessitated en bloc aortic and, on 3 occasions, iliac artery resection for complete tumor removal. Aortic continuity was restored by a woven Dacron tube or bifurcated graft. All grafts were covered with omentum. There were no postoperative vascular complications. Pathological study of the residual retroperitoneal disease demonstrated that 2 patients had mature teratoma only, 2 had mature teratoma with occasional nests of immature teratoma and 2 had residual yolk sac, embryonal or choriocarcinoma elements. The latter 2 patients underwent postoperative salvage chemotherapy with varying combinations of bleomycin, etoposide, ifosfamide and cisplatin. At 4 to 55 months 4 patients were disease-free, while 2 died of metastatic disease. No problems related to the aortic reconstruction have occurred. This small experience demonstrates that, if necessary, complete surgical en bloc extirpation of bulky metastatic germ cell tumors and the aorta/iliac artery can be performed safely with a satisfactory long-term outcome.

Adult↗
PubMed1994

Isolation and sequence of the t-RNA ligase-encoding gene of Candida albicans.

The gene encoding tRNA ligase from Candida albicans was isolated from a genomic library by complementation of a Saccharomyces cerevisiae strain containing a disrupted structural gene, RLG1, encoding tRNA ligase. The cloned gene also complements a temperature-sensitive allele of RLG1. Sequence analysis revealed a single 2499-nt coding region. The gene encodes a protein of 833 amino acids that is 42% identical to S. cerevisiae tRNA ligase. Hybridization to chromosomes of C. albicans separated by pulsed-field gel electrophoresis located the gene to chromosome 1, the smallest C. albicans chromosome.

Amino Acid Sequence↗
PubMed1994

Heterologous transformation of Zalerion arboricola.

A heterologous DNA-mediated transformation system was developed for the pneumocandin-producing fungus Z. arboricola that was based on either conferral of hygromycin B resistance or complementation of a nitrate reductase mutant. Hygromycin-resistant transformants were selected with plasmid pCSN43 which contains the E. coli hygromycin B phosphotransferase gene under the control of Aspergillus nidulans trpC transcription signals. Transformation frequencies were about four transformants per microgram of circular DNA and could be improved four- to six-fold by linearizing the transforming DNA. The transformants differed from one another with respect to the copy number of the integrated plasmid and the site of integration. Adding an autonomously-replicating sequence (AMA1) from A. nidulans to pCSN43 enhanced transformation three-fold and produced, in addition, numerous abortive transformants. However, it is unlikely that the AMA1 sequence promoted plasmid replication in Z. arboricola. Nitrate reductase mutants of Z. arboricola were isolated by positive selection on chlorate-containing medium, and one mutant was subsequently transformed with pSTA700 which contains the nitrate reductase gene (niaD) from Cephalosporium acremonium. Introduction of the niaD gene restored sensitivity to chlorate in the mutant; therefore, using the niaD gene as a selectable marker provides a system for both positive and negative selection. To our knowledge, this is the first report describing transformation of a member of the genus Zalerion.

Acremonium↗
PubMed1994

Papulonecrotic tuberculide and erythema induratum as presenting manifestations of tuberculosis.

We describe a patient with two tuberculides, erythema induratum and papulonecrotic tuberculide. At presentation these were the only manifestations of tuberculosis and they responded dramatically to antituberculous therapy. With the rise in incidence of tuberculosis in Western countries these and other presentations of tuberculosis will be seen with increasing frequency and may provide the only clue to the underlying diagnosis.

Adult↗