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Biomedical subjects

J Yu

Publications and source records attributed to J Yu.

At least 91 records · Page 5Linked to original sources
PubMed1997

Pulmonary drug delivery: physiologic and mechanistic aspects.

Peptide and protein drugs are being used increasingly in major research and development programs in the pharmaceutical industry and are also an important class of therapeutic agents due to advances in genetic engineering and biotechnology. Systemic delivery of these macromolecular drugs, however, has been limited to the parenteral route largely because of their extensive presystemic elimination when taken orally. Faced with this dilemma concerning the systemic delivery of these macromolecules with their unique conformational complexity for therapeutic activity, pharmaceutical scientists have evaluated the potential of various non-oral routes of administration as alternatives. Despite the tremendous efforts that have been devoted to this problem, only limited success has been achieved--mostly with small peptides. Growing attention has been given to the potential of a pulmonary route as an alternative non-invasive means for systemic delivery of peptide/protein-based therapeutic agents due to the fact that the lung provides a huge but extremely thin absorptive mucosal membrane. Although current studies show great promise, pulmonary delivery of therapeutic peptides and proteins is complicated by the complexity of the anatomic structure of the human respiratory system and the influence on drug deposition exerted by respiration. This review discusses the fundamental structure and physiology of the human respiratory system, current methodology used to study pulmonary drug absorption, approaches of drug delivery to the distal lung, and recent progress in pulmonary drug delivery by case studies. The mechanisms of pulmonary drug absorption are also discussed.

Absorption↗
PubMed1997

Analysis of clonality of lymphocytic leukemia and lymphoma by T-cell receptor gene rearrangement.

OBJECTIVE: To analyse the relationship between the number of T-cell receptor (TCR) gamma gene rearrangement and clonality of malignant cells in lymphocytic leukemia and lymphoma. METHODS: The TCR gamma gene characteristics of 73 cases of lymphocytic leukemia and lymphoma and other diseases that had presented 1 or 2 prominent bands of amplified TCR gamma VI subgroups-J1/2 gene rearrangement (GR) were detected by polymerase chain reaction-restriction enzymes (PCR-RE), heteroduplex formation (HDF), DNA sequencing and single-strand conformational polymorphism (SSCP). RESULTS: Thirty-four percent patients had 2 of TCR gamma GR (biallelic rearrangement); twenty-six percent had 1 of TCR gamma GR; fifty-four percent of acute lymphocytic leukemia's and nineteen percent of non-Hodgkin's lymphomas (NHL) had 2 of TCR gamma GR. HDF could rapidly confirm more than 1 of alleles while more alleles were difficult to be recognized by restriction analysis. Sense and antisense strands of heteroduplex were composed of 2 of TCR gamma GR respectively. By combining HDF method, oligoclonalities in three patients (2 acute lympholytic leukemia and 1 myelodysplastil syndrome and clone evolution in one NHL were found. CONCLUSIONS: The fact that many patients had 2 of TCR GR means that complications of two neoplastic clones can be affirmed only if more than 2 of TCR GR are found. HDF can be used to detect the clonality, oligoclonality and polyclonality of lymphoid cells in lymphocytic leukemia and lymphoma by analysis of the difference of gene segments. HDF is a reliable method for the clone evolution research of lymphoid malignancies in progression.

Base Sequence↗
PubMed1996

Sec61-mediated transfer of a membrane protein from the endoplasmic reticulum to the proteasome for destruction.

The human cytomegalovirus genome encodes proteins that trigger destruction of newly synthesized major histocompatibility complex (MHC) class I molecules. The human cytomegalovirus gene US2 specifies a product capable of dislocating MHC class I molecules from the endoplasmic reticulum to the cytosol and delivering them to the proteasome. This process involves the Sec61 complex, in what appears to be a reversal of the reaction by which it translocates nascent chains into the endoplasmic reticulum.

Adenosine Triphosphate↗
PubMed1996

Cholinergic neurons from different subdivisions of the basal forebrain lack connectional specificity for cerebral cortical target sites in vitro.

Basal forebrain cholinergic neurons send their axons to cerebral cortex in a topographically organized projection. Experiments tested the hypothesis that this topographic organization results from target preferences of the cholinergic neurons. Slices containing either medial septum or substantia innominata were grown in co-culture with slices of lateral neocortex and hippocampus. Cholinergic neurons from septum and from substantia innominata projected axons into neocortex and hippocampus, without obvious differences in pattern or density. These data suggest that basal forebrain cholinergic neurons can innervate any portion of the cerebral mantle.

Acetylcholinesterase↗
PubMed1996

Frequent deletion in the methylthioadenosine phosphorylase gene in T-cell acute lymphoblastic leukemia: strategies for enzyme-targeted therapy.

Methylthioadenosine phosphorylase (MTAP), an enzyme essential for the salvage of adenine and methionine, is deficient in a variety of cancers, including acute lymphoblastic leukemia (ALL). Because the MTAP gene is located adjacent to the tumor-suppressor gene p16 on chromosome 9p21 and more than 60% of T-cell ALL (T-ALL) patients have deletion in the p16 gene, we examined the status of the MTAP gene in T-ALL patients. Quantitative polymerase chain reaction amplification of exon 8 of MTAP showed a deletion in 16 of 48 (33.3%) patients at diagnosis and in 13 of 33 (39.4%) patients at relapse. Southern blot analysis showed that, in addition to deletion of the entire MTAP gene, a common break point was between exons 4 and 5, resulting in deletion of exons 5 through 8. The finding of frequent deficiency of MTAP in T-ALL offers the possibility of an enzyme targeted therapy for T-ALL. MTAP(-) T-ALL-derived cell line, CEM cells were very sensitive to methionine deprivation, with cell viability at 50% of control as early as 48 hours after methionine deprivation. In contrast, methionine deprivation had little effect on the viability of normal lymphocytes or on their proliferative response to phytohemagglutinin. Alanosine, an inhibitor of AMP synthesis, inhibited the growth of both MTAP(+) (Molt-4 and Molt-16) and MTAP(-) (CEM and HSB2) cell lines. However, the addition of methylthioadenosine, the substrate of MTAP, protected the MTAP(+) cells but not the MTAP(-) cells from alanosine toxicity. These findings suggest the possibility of targeting MTAP for selective therapy of T-ALL.

Adenosine Monophosphate↗
PubMed1996

YY1 and c-Myc associate in vivo in a manner that depends on c-Myc levels.

The c-Myc oncoprotein has previously been shown to associate with transcription regulator YY1 and to inhibit its activity. We show herein that endogenous c-Myc and YY1 associate in vivo and that changes in c-Myc levels, which accompany mitogenic stimulation or differentiation of cultured cells, affect the ratio of free to c-Myc-associated YY1. We have also investigated the mechanism by which association with c-Myc inhibits YY1's ability to regulate transcription. c-Myc does not block binding of YY1 to DNA. However, protein association studies suggest that c-Myc interferes with the ability of YY1 to contact basal transcription proteins TATA-binding protein and TFIIB.

3T3 Cells↗
PubMed1996

A knock-out model of paroxysmal nocturnal hemoglobinuria: Pig-a(-) hematopoiesis is reconstituted following intercellular transfer of GPI-anchored proteins.

We created a "knockout" embryonic stem cell via targeted disruption of the phosphatidylinositol glycan class A (Pig-a) gene, resulting in loss of expression of cell surface glycosyl phosphatidylinositol-anchored proteins and reproducing the mutant phenotype of the human disease paroxysmal nocturnal hemoglobinuria. Morphogenesis of Pig-a- embryoid bodies (EB) in vitro was grossly aberrant and, unlike EB derived from normal embryonic stem cells, Pig-A EB produced no secondary hematopoietic colonies. Chimeric EB composed of control plus Pig-A- cells, however, appeared normal, and hematopoiesis from knock-out cells was reconstituted. Transfer in situ of glycosyl phosphatidylinositol-anchored proteins from normal to knock-out cells was demonstrated by two-color fluorescent analysis, suggesting a possible mechanism for these functional effects. Hematopoietic cells with mutated PIG-A genes in humans with paroxysmal nocturnal hemoglobinuria may be subject to comparable pathophysiologic processes and amenable to similar therapeutic protein transfer.

Animals↗
PubMed1996

Effects of intraventricular transplantation of NGF-secreting cells on cholinergic basal forebrain neurons after partial immunolesion.

The aim of the present study was to examine the effects of nerve growth factor on brain cholinergic function after a partial immunolesion to the rat cholinergic basal forebrain neurons (CBFNs) by 192 IgG-saporin. Two weeks after intraventricular injections of 1.3 micrograms of 192 IgG-saporin, about 50% of CBFNs were lost which was associated with 40-60% reductions of choline acetyltransferase (ChAT) and high-affinity choline uptake (HACU) activities throughout the basal forebrain cholinergic system. Two groups of lesioned animals received intraventricular transplantations of mouse 3T3 fibroblasts retrovirally transfected with either the rat NGF gene (3T3NGF+) or the retrovirus alone (3T3NGF-) and were sacrificed eight weeks later. In vivo production of NGF by 3T3NGF+ cells was confirmed by NGF immunohistochemistry on the grafts and NGF immunoassay on cerebrospinal fluid (CSF) samples. Both ChAT and HACU activities returned to normal control levels in the basal forebrain and cortex after 3T3NGF+ transplants, whereas no recovery was observed in 3T3NGF- transplanted animals. There was a 25% increase in the size of remaining CBFNs and an increased staining intensity for NGF immunoreactivity in these cells after NGF treatments. Acetylcholinesterase (AChE) histochemistry revealed that the optical density of AChE-positive fibers in the cerebral cortex and hippocampus were reduced by about 60% in immunolesioned rats which were completely restored by 3T3NGF+ grafts. In addition, decreases in growth-associated protein (GAP)-43 immunoreactivity after immunolesion and increases in synaptophysin immunoreactivity after 3T3NGF+ grafts were observed in the hippocampus. Our results further confirm the notion that transfected NGF-secreting cells are useful in long-term in vivo NGF treatment and NGF can upregulate CBFN function. They also highly suggest that NGF induces terminal sprouting from remaining CBFNs.

3T3 Cells↗
PubMed1996

Sex differences in estrogen receptor and progestin receptor induction in the guinea pig hypothalamus and preoptic area.

Quantitative in vitro autoradiography was used to determine if regional sex differences in estrogen receptor (ER) content and/or estrogen responsiveness, as indicated by an increase in progestin receptor (PR), are present in the adult guinea pig brain. Adult male and female guinea pigs were gonadectomized 1 week before subcutaneous injection of 25 micrograms estradiol benzoate (EB)/kg body wt or the sesame oil vehicle. Animals were killed by decapitation 44 h after injection. Unoccupied PRs, and unoccupied and occupied ERs, were measured in discrete brain regions by quantitative in vitro autoradiography using [3H]R5020 and [3H]estradiol as ligands, respectively. In vehicle-injected controls, a higher level of ER was found in the arcuate nucleus (ARC), dorsal medial nucleus (DMN) and ventrolateral nucleus (VLN) of females as compared to males. At 44 h after EB injection, 32-55% of the ERs were occupied; however, EB treatment caused a marked down-regulation of total receptor (calculated as occupied+ unoccupied receptor) in most of the brain regions examined, including the periventricular preoptic area (PVP), medial preoptic area (MPO), bed nucleus of the stria terminalis, paraventricular nucleus, ARC, ventrolateral hypothalamus (VLH), VLN, and DMN. In EB-treated animals, PR binding was detectable in the PVP, MPO, ARC, VLH, and VLN, with higher levels of binding observed in the PVP, MPO, and VLN of the female as compared to the male. No PR binding was observed in oil-injected control animals. These results demonstrate region-specific sex differences in ER as well as estrogen-induced regulation of progestin and ERs in the guinea pig brain. The discordance between the regional distributions of sex differences in ER and estrogen-induced PR implies that sex differences in ER and estrogen-induced PR implies that sex differences in estrogen response may not be clearly linked to a sex difference in receptor number. Instead, sex differences in response may involve differences in receptor number within specific subpopulations of estrogen target cells or may involve differences in ER dynamics.

Animals↗
PubMed1996

Localization of the homolog of a mouse craniofacial mutant to human chromosome 18q11 and evaluation of linkage to human CLP and CPO.

The transgene-induced mutation 9257 and the spontaneous mutation twirler cause craniofacial and inner ear malformations and are located on mouse chromosome 18 near the ataxia locus ax. To map the human homolog of 9257, a probe from the transgene insertion site was used to screen a human genomic library. Analysis of a cross-hybridizing human clone identified a 3-kb conserved sequence block that does not appear to contain protein coding sequence. Analysis of somatic cell hybrid panels assigned the human locus to 18q11. The polymorphic microsatellite markers D18S1001 and D18S1002 were isolated from the human locus and mapped by linkage analysis using the CEPH pedigrees. The 9257 locus maps close to the centromeres of human chromosome 18q and mouse chromosome 18 at the proximal end of a conserved linkage group. To evaluate the role of this locus in human craniofacial disorders, linkage to D18S1002 was tested in 11 families with autosomal dominant nonsyndromic cleft lip and palate and 3 families with autosomal dominant cleft palate only. Obligatory recombinants were observed in 8 of the families, and negative lod scores from the other families indicated that these disorders are not linked to the chromosome 18 loci.

Alleles↗
PubMed1996

Normal development of mice lacking metablastin (P19), a phosphoprotein implicated in cell cycle regulation.

Metablastin, also called P19, stathmin, prosolin, Lap18, and oncoprotein18, is a highly conserved cytosolic protein that undergoes extracellular factor- and cell cycle-regulated serine phosphorylation and developmentally regulated expression in mammals. It has been implicated in a variety of cellular functions including growth and differentiation, and recent evidence suggests an involvement in cell cycle control. To explore its potential role in mammalian development, we have disrupted the gene encoding metablastin by gene targeting in mice. The metablastin null mutants have no overt phenotype regarding development, growth rate, behavior, T cell maturation, or fertility and do not exhibit an increased predisposition to tumors. SCG10, a protein closely related in structure to metablastin, shows no compensatory up-regulation in metablastin-/- mice. Although the data suggest that metablastin is not essential for mammalian development, the knockout mice should prove valuable in exploring the role of this protein in cell cycle regulation.

Animals↗
PubMed1996

Study of receptor-mediated neurotoxins released by HIV-1-infected mononuclear phagocytes found in human brain.

Although there is growing evidence that neurotoxic molecules produced by HIV-1-infected mononuclear phagocytes damage neurons, the precise mechanisms of neuronal attack remain uncertain. One class of cytotoxin involves neuronal injury mediated via the NMDA receptor. We examined blood monocytes and brain mononuclear cells isolated at autopsy from HIV-1-infected individuals for the ability to release NMDA-like neuron-killing factors. We found that a neurotoxic amine, NTox, was produced by blood monocytes and by brain mononuclear phagocytes infected with retrovirus. In vivo injections of minute quantities of NTox produced selective damage to hippocampal pyramidal neurons. NTox can be extracted directly from brain tissues infected with HIV-1 and showed structural features similar to wasp and spider venoms. In contrast to NTox, HIV-1 infection did not increase the release of the NMDA excitotoxin quinolinic acid (QUIN) from mononuclear cells. Although we found modest elevations of QUIN in the CSF of HIV-1-infected individuals, the increases were likely attributable to entry through damaged blood-brain barrier. Taken together, our data pinpoint NTox, rather than QUIN, as a major NMDA receptor-directed toxin associated with neuro-AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Assembly of high-resolution restriction maps based on multiple complete digests of a redundant set of overlapping clones.

An approach to restriction-site mapping and contig building that uses fragment-size data from multiple complete digests of a set of clones that oversample a genomic region is presented. Maps containing both fragment-length data and clone-end data are maintained for each restriction enzyme. Synchronization between the maps for the different enzymes is achieved by requiring the clone-end maps for all enzymes to be compatible. Basic concepts that underlie multiple-complete-digest mapping--including the match/merge approach to map incorporation, extension vs assimilation, ambiguity, and clone-end compatibility--are presented. An initial application of multiple-complete-digest mapping to real data on a set of cosmid clones suggests that this mapping method has exceptional power to produce accurate maps that are well suited to the needs of large-scale DNA-sequencing projects.

Algorithms↗
PubMed1996

Hormonal regulation of CREB phosphorylation in the anteroventral periventricular nucleus.

The anteroventral periventricular nucleus (AVPV) is a nodal point in neural circuits regulating secretion of gonadotropin and contains sexually dimorphic populations of hormonally regulated dopamine-, dynorphin-, and enkephalin-containing neurons. Because the tyrosine hydroxylase (TH), prodynorphin (PDYN), and proenkephalin (PENK) genes contain cAMP response elements that control their expression in their promoters, we used histochemical methods to determine whether ovarian steroids alter expression of the cAMP response element-binding protein (CREB) in the AVPV. Because the ability of CREB to activate transcription depends on phosphorylation at Ser133, we also evaluated the effects of acute steroid treatment on levels of phosphorylated CREB (pCREB) in AVPV neurons by using an antibody that differentiates between CREB and pCREB. Treatment of ovariectomized rats with estradiol treatments caused a significant induction in the number of pCREB-immunoreactive nuclei within 30 min that was maintained for at least 4 hr, but did not alter CREB immunostaining in the AVPV. Pretreatment with the estrogen antagonist Nafoxidine blocked this induction. In contrast, acute administration of progesterone to estrogen-primed animals suppressed and then increased pCREB staining in the ASVPV at 30 and 60 min, respectively; no significant differences between experimental and control animals were apparent by 2 hr after progesterone treatment. Double-labeling experiments showed that pCREB was colocalized with PDYN, PENK, or TH mRNA in the AVPV, suggesting that pCREB may mediate the effect of steroid hormones on gene expression in these neurons.

Animals↗
PubMed1996

Altered NGF protein levels in different brain areas after immunolesion.

Nerve growth factor (NGF) provides critical trophic support to the cholinergic basal forebrain neurons that express high levels of the low-affinity NGF receptor (p75NGFR) in the adult rat brain. Intraventricular injection of 192 IgG-saporin, made by coupling the monoclonal antibody to p75NGFR 192 IgG to the cytotoxin saporin, selectively destroys the p75NGFR-bearing neurons in the basal forebrain and was used here to examine the effects of selective cholinergic lesions on brain NGF protein levels. We showed that 192 IgG-saporin produced significant long-lasting elevation of NGF protein levels in the hippocampus, cortex, and olfactory bulb, with profound reductions of ChAT activities representing complete cholinergic deafferentations of these areas. NGF level was maintained in the basal forebrain, even though there was almost complete loss of p75NGFR-immunoreactive cells and significant decrease of ChAT activity. In addition, a mild glial response was observed in the basal forebrain, and most of the activated astroglia expressed NGF-like immunoreactivity there. The increases in NGF protein levels in the target areas of the basal forebrain were most likely due to loss of cholinergic basal forebrain neurons and retrograde transport of NGF from these areas. Glial-derived NGF is partially responsible for the maintained level of NGF in the basal forebrain after the loss of cholinergic neurons. The accumulation of NGF protein in the target areas may have some effects on synaptic rearrangement in denervated tissues.

Animals↗
PubMed1996

Dielectric properties of human fetal organ tissues at radio frequencies.

The in vitro dielectric properties of human fetal organ tissues were measured in the frequency range from 100 kHz to 500 MHz at 24 degrees C. The dielectric measurements were performed by using a network analyzer (HP4195A) and a coaxial line capacitive sensor. The tested samples, including skin, muscle, heart, lung, liver, kidney, spleen, and brain tissues, were obtained from the legal abortion of five women with 14-16 weeks gestation periods.

Abortion, Legal↗
PubMed1996

Detection and characterization of primary liver cancer in rats by MS-264-enhanced MRI.

A new MR contrast agent, MS-264 (Gd(1RS)-1-(p-butylbenzyl)-DTPA), was developed to achieve hepatobiliary specificity and its potential evaluated for detecting and characterizing liver tumors in rats with chemically induced hepatocellular carcinoma (HCC). In seven rats with 66 HCC lesions, enhancements of different abdominal organs and tumors were compared on T1-weighted images after intravenous administration of Gd-DTPA (0.3 mmol/kg) and MS-264 (0.05 mmol/kg). MR images were correlated with postmortem microangiographic and histological findings. An overall enhancement of different organs, which normalized within 24 h, was observed after Gd-DTPA and MS-264 injection. MS-264 caused a higher relative enhancement (RE) in liver (60%), compared with that of Gd-DTPA (40%), which resulted in a prompt negative contrast enhancement in 59 of 66 HCCs. All were moderately to poorly differentiated (Grades II-IV) tumors. Six of these 59 negative contrast-enhancing lesions showed a positively enhanced peritumoral rim, which corresponded histologically to malignant infiltration (n = 2) or compression (n = 4). On the other hand, six well differentiated HCCs showed prolonged positive enhancement. However, one well differentiated HCC was not positively enhanced by MS-264, probably due to poor access of the agent to the lesion. In comparison to that of the precontrast images, enhancement with Gd-DTPA and MS-264 increased the number of detected lesions by 22 and 42%, respectively. In this animal study, MS-264 proved to be useful in detection and characterization of primary liver cancers.

Animals↗