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Biomedical subjects

R Kang

Publications and source records attributed to R Kang.

34 records · Page 2Linked to original sources
PubMed1996

Alternative splicing of the pyruvate kinase M gene in a minigene system.

The M1-type and M2-type isozymes of pyruvate kinase are produced from a single gene by mutually exclusive use of exons 9 and 10. Selection of exon 10 generates the M2 type, which occurs in most tissues, whereas the M1 type is expressed by use of exon 9 only in skeletal muscle, heart and brain. We investigated the mechanism by which exon 10, but not exon 9 is selected in M2-expressing cells by transfecting minigenes containing exon 9 and/or exon 10 in cells and by analyzing the transcripts using reverse-transcriptase polymerase chain reaction. Deletion of the most conserved region in intron 8 did not affect selection of exon 10 in dRLh-84 cells, which express only the M2 type. Exclusion of exon 10 from the minigene resulted in two major spliced products. One included correctly spliced exon 9 and the other skipped this exon. Similar splicing patterns were observed when these minigenes were transfected in hepatocytes which express the L type, but not M1 or M2 types. The 5' splice site but not the 3' splice site of exon 9 was found to be hardly recognized by the splicing machinery in dRLh-84 cells. Mutation of the 5' splice site sequence of exon 9 to that of exon 10 and vice versa did not change the splicing patterns. However, mutation of this site of exon 9 to a perfectly complementary sequence of U1 snRNA resulted in selection of exon 9 correctly spliced to exon 10. A 9-10 fusion exon (constructed by substitution of 68 bases of the 3' portion of exon 9 and 33 bases of the 5' portion of intron 9 for the corresponding regions of exon 10 and intron 10) was also correctly incorporated into a major product together with exon 10. Thus, we propose that exon 9 is not recognized in non M1-expressing cells due to the weak signal of its 5' splice site and that, although the 5' splicing signal of exon 10 also appears to be weak, this exon can be recognized in these cells because the 5' recognition signal may be relatively strengthened by cis-acting element(s) which may be present in the 3' portion of exon 9 and the 5' portion of intron 9 and/or the corresponding regions of exon 10 and intron 10.

Alternative Splicing↗
PubMed1996

Relationship between the concentrations of glycolytic intermediates and expression of the L-type pyruvate kinase gene in cultured hepatocytes.

Previous studies have suggested that some glycolytic intermediates are involved in the regulation of L-type pyruvate kinase gene expression by carbohydrates such as glucose and fructose. To find such intermediates, we examined the relationship between the levels of L-type pyruvate kinase mRNA and glycolytic metabolites in hepatocytes cultured under various conditions. Of the metabolites, the levels of 3-phosphoglycerate and phosphoenol-pyruvate only increased significantly under conditions under which the expression of the L-type pyruvate kinase gene was stimulated. The level of glucose 6-phosphate, which was reported to be involved in dietary stimulation of this gene expression, was not correlated with the mRNA level since marked accumulation of deoxyglucose 6-phosphate occurring on the addition of deoxyglucose, a nonmetabolizable glucose analog, was not accompanied by an increase in the L-type pyruvate kinase mRNA level. In addition, we found that fructose at a low concentration in the presence of glucose failed to increase the mRNA and metabolite levels in contrast to other reports that the promoter activity of the L-type pyruvate kinase gene is stimulated by this treatment. Thus we propose that 3-phosphoglycerate and/or phosphoenolpyruvate are involved in the carbohydrate regulation of L-type pyruvate kinase gene expression.

Animals↗
PubMed1996

Gene transfer to the rabbit patellar tendon: potential for genetic enhancement of tendon and ligament healing.

Injuries to ligaments and tendons occur very commonly, but often heal very poorly. A number of growth factors show promise as biological agents with which to augment the reparative responses of these tissues, but they are extremely difficult to deliver clinically. We have suggested the use of gene transfer as a possible way to obviate this limitation. Here we have used the lacZ marker gene to evaluate methods for gene delivery to ligaments and tendons. Cell cultures were established from the following tissues of the New Zealand white rabbit: anterior and posterior cruciate ligaments, medial collateral ligament, patellar tendon and semitendionsus. In vitro experiments confirmed that these cells were very efficiently transduced by an E1- E3- adenoviral vector carrying the lacZ gene. Cells derived from ligaments and tendons also proved readily susceptible to retroviral transduction and, following transfer of the ned gene, selection in G418. To determine whether these cells could be genetically altered in situ, gene transfer to the patellar tendons of rabbits' knee joints was attempted using an adenovirus for in vivo delivery and a retrovirus for ex vivo delivery. Direct, percutaneous injection of the adenovirus resulted in high levels of lacZ expression, but this was limited to the area of tendon immediately adjacent to the injection site, and preferentially labeled cells in the epitenon sheath. An unexpected finding of these studies was the in vivo adenoviral transduction of bone cells in areas where the tendon insertion site had been accidentally injected. Allotransplantation of tendon fibroblasts into which the lacZ gene had been retrovirally introduced led to lacZ expression throughout the body of the tendon itself. The genetically altered cells appeared able to migrate from the site of injection and to integrate themselves into the crimp pattern of the tissue. Both in vivo and ex vivo methods led to gene expression for at least 6 weeks, which may be long enough for clinical purposes.

Adenoviridae↗
PubMed1995

Preterm infant follow-up project: a multi-site field experiment of hospital and home intervention programs for mothers and preterm infants.

This study was designed as a multi-site field experiment to test the efficacy of hospital and home visit interventions to improve interaction between mothers and preterm infants. Hospital intervention consisted of State Modulation (SM) treatment, which focused on teaching mothers to read the behavioral cues and modulate the states of consciousness of preterm infants during feedings. Home visit intervention was a field-tested program, Nursing Systems for Effective Parenting-Preterm (NSTEP-P), implemented during the first five months after the infant's hospital discharge. A hospital program on car seats (CS) and standard public health nursing home visits (PHN) served as comparison treatments. The sample consisted of 327 mothers and their preterm infants who were less than 36 weeks of gestational age at hospital discharge. Mothers were randomly assigned to intervention groups on the basis of their education. High education (HE) was > or = 13 years of education, while low education (LE) was < or = 12 years of education. HE mothers were only assigned to hospital programs, while LE mothers were assigned to combinations of hospital and home visit programs. Evaluations were conducted at 40 weeks conceptual age (expected date of birth), at 46 weeks conceptual age (1.5-months-corrected age), and 60 weeks conceptual age (5-months-corrected age). Comparisons were made within each educational group. For HE groups, SM infants gave significantly more clear cues during observations of feeding interactions at 1.5-months-corrected age and teaching interactions at 5-months-corrected age than infants in the CS group. During the teaching interaction, well-educated SM mothers provided significantly more social-emotional and cognitive stimulation than CS mothers. For LE groups, infants in the SM group combined with either PHN or NSTEP-P exhibited significantly more responsive behavior during feeding observations than those infants in the CS/PHN group at 1.5-months-corrected age. LE mothers in the SM/NSTEP-P group demonstrated more sensitivity and more stimulation during teaching interactions at 5-months-corrected age than mothers in the SM/PHN or CS/PHN groups. Findings suggest that State Modulation treatment is effective in influencing positive social interaction of infants regardless of the level of maternal education. State modulation treatment combined with NSTEP-P is most effective in improving the social interaction between preterm infants and mothers with limited formal education. Such treatment-specific programs suggest avenues for providing cost-effective care that complements the changing transactional needs of mothers and preterm infants.

Adolescent↗
PubMed1995

Building community capacity for health promotion: a challenge for public health nurses.

The centennial celebration of public health nursing is a strong reminder of the tradition and practice of public health nursing's commitment to communities. Partnerships with communities give public health nurses fiduciary responsibility to be actively involved in public health reform to advance health promotion and health protection. Public health nurses must rise to the challenge to build community capacity through facilitating community participation, enhancing community health services, and coordinating public policy to achieve core public health responsibilities of assessment, policy, and assurance. This paper explicates strategies for building community capacity for health promotion.

Community Health Services↗
PubMed1995

Entry of Escherichia coli into stationary phase is indicated by endogenous and exogenous accumulation of nucleobases.

Endogenous and exogenous accumulation of nucleobases was observed when Escherichia coli entered the stationary phase. The onset of the stationary phase was accompanied by excretion of uracil and xanthine. Except for uracil and xanthine, other nucleobases (except for minor amounts of hypoxanthine), nucleosides, and nucleotides (except for cyclic AMP) were not detected in significant amounts in the culture medium. In addition to exogenous accumulation of nucleobases, stationary-phase cells increased the endogenous concentrations of free nucleobases. In contrast to extracellular nucleobases, hypoxanthine was the dominating intracellular nucleobase and xanthine was present only in minor concentrations inside the cells. Excretion of nucleobases was always connected to declining growth rates. It was observed in response to entry into the stationary phase independent of the initial cause of the cessation of cell growth (e.g., starvation for essential nutrients). In addition, transient accumulation of exogenous nucleobases was observed during perturbations of balanced growth conditions such as energy source downshifts. The nucleobases uracil and xanthine are the final breakdown products of pyrimidine (uracil and cytosine) and purine (adenine and guanine) bases, respectively. Hypoxanthine is the primary degradation product of adenine, which is further oxidized to xanthine. The endogenous and exogenous accumulation of these nucleobases in response to entry into the stationary phase is attributed to degradation of rRNA.

Cell Cycle↗
PubMed1994

Description of the clinical practice of advanced practice nurses in family-centered early intervention in two rural settings.

The purpose of this study was to describe the scope of clinical practice of advanced practice nurses who were involved in a project designed to increase access of families with at-risk and disabled young children, newborn to 3 years of age, to early intervention services in rural Washington State. The findings from this study are based on the retrospective review of records of clients seen by the advanced practice nurses. Nursing diagnoses and nursing interventions were assigned to chart recordings. The most frequently occurring nursing diagnoses assigned to parents were Altered Parenting, Altered Family Processes, Fear, Noncompliance, and Knowledge Deficit. The most frequently occurring nursing diagnoses assigned to children were Impaired Physical Mobility, Impaired Verban Communication, Altered Nutrition: Less than Body Requirements, Sensory-Perceptual Alteration, and Altered Thought Processes. Categories of nursing intervention recorded most frequently were Monitoring, Planning and Information. Discussion of findings addresses the roles and reimbursement of advanced practice nurses who provide family-centered early intervention services in rural communities.

Child, Preschool↗
PubMed1992

Microvascular changes in rat glomeruli as a consequence of small differences in selenium exposure.

This paper evaluates the effect of small differences in selenium exposure, within the safe range, on the glomerular vascular tufts of rats fed high-sucrose diets. In the first experiment male Wistar rats were housed in galvanized cages and were provided sucrose-based diets to induce a mild chronic insult to the microcirculation. One group of rats received the diet prepared to contain 0.10 mg Se/kg and another group 0.21 mg Se/kg. To assure that the galvanized metal cages were not influencing the results of the experiment this protocol was repeated in a second experiment wherein rats were housed in stainless steel cages. The levels of Se used supported normal activity of the long-term indicator of Se sufficiency, erythrocyte glutathione peroxidase. In both experiments rats fed diets containing 0.21 mg Se/kg had larger Bowman's capsules (P < 0.01) and vascular tufts (P < 0.01). Vascular tufts from these rats also contained a higher proportion of open capillary lumen (P < 0.01), contained less cytoplasmic and extracellular material (P < 0.001), and had larger nuclei (P < 0.001) than those fed 0.10 mg Se/kg. A third study was designed to determine if the selenium-dependent differences in nuclear size were indicative of this being a site of incorporation. Year-old rats subjected to the same protocol as those in the second experiment were given 75Se, by injection into the femoral vein, to label the sites of incorporation. Glomeruli were purified and subjected to subcellular fractionation. Ninety percent of the radioactivity was associated with the crude nuclear fraction. Purification of the crude nuclear fraction demonstrated that the radioactivity was associated with the nuclei.

Animals↗
PubMed1985

Convergence of sensory inputs in somatosensory cortex: interactions from separate afferent sources.

Intracellular recording techniques were used to test for cross-modality and topographic convergence among inputs to area 3a of cerebral cortex. Recordings were made within the projection area of group I afferent fibers of the deep radial nerve in barbiturate-anesthetized cats. Epsps were evoked in 90% of neurons (81/90) by electrical stimulation of more than one nerve of the contralateral forelimb. The deep radial nerve evoked the shortest latency epsps within this region of cortex and the only ones likely to be mediated by a monosynaptic thalamocortical pathway. However, the epsps evoked from other forelimb nerves (of deep or cutaneous origin) had mean latencies only a few milliseconds (1.3-3.0 ms) longer. Furthermore, there were a variety of interactions among inputs from separate afferent sources. The observed interactions included spatial facilitation, occlusion and afferent inhibition. The consequence of these interactions was that neuronal responses were shaped by combinations of effects from different topographic regions of the forelimb or of different modalities. The findings are interpreted as indicating a sharing of neurons among pathways to cortical neurons from separate afferent sources. Interactions between ascending pathways by way of such shared neurons may contribute to the modulation or plasticity of somatosensory responsiveness during behavior or after deafferentation.

Animals↗
PubMed1985

Responses of cat motor cortex neurons to cortico-cortical and somatosensory inputs.

Intracellular techniques were used to investigate a cortico-cortical path from sensory cortex to motor cortex of cats. Cortico-cortical epsps were evoked in motor cortex neurons by microstimulation of area 3a. Epsps with latencies between 1.2 and 2.4 ms were identified as monosynaptic. These short latency cortico-cortical effects were recorded in layers II through VI of the motor cortex. Neurons with monosynaptic cortico-cortical epsps also received excitatory inputs from forelimb nerves, usually from both muscle and cutaneous afferent fibers. The epsps evoked from forelimb nerves in motor cortex neurons were preceded by neural activity in somatosensory cortex. Time delays between arrival of inputs in sensory cortex and in motor cortex were compared to the latencies of cortico-cortical epsps in the same motor cortex neurons. It was apparent that the timing was appropriate for the identified cortico-cortical path to have relayed some sensory inputs to motor cortex.

Animals↗
PubMed1983

Interactions among convergent inputs to somatosensory cortex neurons.

Postsynaptic potentials (psps) produced by electrical stimulation of 4 forelimb nerves were recorded intracellularly from neurons in the primary somatosensory cortex of sodium pentobarbital anesthetized cats. Convergent inputs were found from nerves subserving different modalities and different regions of the forelimb. Psps from separate afferent sources usually did not sum linearly but rather interacted with one another. These interactions could have occurred at the cortical level or earlier in the ascending pathways and are interpreted with regards to the control of somatosensory responsiveness by multiple converging inputs.

Animals↗
PubMedDate not supplied

Clinical gene therapy for arthritis.

To overcome problems associated with conventional drug delivery in the treatment of rheumatoid arthritis (RA) our laboratory has been exploring the application of gene transfer as a means to express therapeutic proteins intraarticularly. Initial experiments in rabbit knee joints demonstrated that the gene encoding interleukin (IL)-1 receptor antagonist (IL-1RA) could be delivered to the synovial lining and expressed at a therapeutic level. The success of these experiments has led to the initiation of a clinical trial to assess the safety and efficacy of using gene therapy to treat RA. For this procedure autologous synoviocytes are retrovirally transduced in culture to express IL-1RA, and are transplanted into two metacarpophalangeal (MCP) joints of the hand. For comparative controls nonmodified synoviocytes are injected into the remaining two MCP joints. During scheduled joint replacement surgery articular tissues and fluids are recovered and analyzed for expression of the IL-1RA transgene. Nine patients will be treated in groups of three; with each group receiving successively higher numbers of transduced synoviocytes. To date five patients have completed the procedure. Thus far it has been well tolerated and intraarticular expression of the IL-1 transgene has been detected by both reverse transcriptase-polymerase chain reaction and in situ hybridization analyses. If this procedure indeed proves to be safe and feasible, future trials will address therapeutic efficacy and involve treatment in patients earlier in the progression of RA.

Journal Article↗