Biomedical subjects

J Kim

Publications and source records attributed to J Kim.

At least 595 records · Page 33Linked to original sources

PubMed1999

Requirement of RBP9, a Drosophila Hu homolog, for regulation of cystocyte differentiation and oocyte determination during oogenesis.

The Drosophila RNA binding protein RBP9 and its Drosophila and human homologs, ELAV and the Hu family of proteins, respectively, are highly expressed in the nuclei of neuronal cells. However, biochemical studies suggest that the Hu proteins function in the regulation of mRNA stability, which occurs in the cytoplasm. In this paper, we show that RBP9 is expressed not only in the nuclei of neuronal cells but also in the cytoplasm of cystocytes during oogenesis. Despite the predominant expression of RBP9 in nerve cells, mutational analysis revealed a female sterility phenotype rather than neuronal defects for Rbp9 mutants. The female sterility phenotype of the Rbp9 mutants resulted from defects in oogenesis; the lack of Rbp9 activity caused the germarium region of the mutants to be filled with undifferentiated cystocytes. RBP9 appears to stimulate cystocyte differentiation by regulating the expression of bag-of-marbles (bam) mRNA, which encodes a developmental regulator of germ cells. RBP9 protein bound specifically to bam mRNA in vitro, which is required for cystocyte proliferation, and the number of cells that expressed BAM protein was increased 5- to 10-fold in the germarium regions of Rbp9 mutants. These results suggest that RBP9 protein binds to bam mRNA to down regulate BAM protein expression, which is essential for the initiation of cystocyte differentiation into functional egg chambers. In hypomorphic Rbp9 mutants, cystocytes differentiated into egg chambers; however, oocyte determination and positioning were perturbed. Therefore, the concentrated localization of RBP9 protein in the oocyte of the early egg chambers may be required for proper oocyte determination or positioning.

3' Untranslated Regions↗

PubMed1999

Developmental expression of aquaporin 1 in the rat renal vasculature.

Aquaporin 1 (AQP-1) is a water channel protein that is constitutively expressed in renal proximal tubule and descending thin limb cells as well as in endothelial cells of the descending vasa recta. Studies in the developing rat kidney have demonstrated that AQP-1 is expressed in renal tubules before birth. However, nothing is known about the expression of AQP-1 in the renal vasculature during kidney development. The purpose of this study was to establish the distribution of AQP-1 in the renal vasculature of the developing rat kidney and follow the differentiation of the vascular system during kidney development. Kidneys from 16-, 17-, 18-, and 20-day-old fetuses and 1-, 4-, 7-, 14-, 21-, and 28-day-old pups were preserved and processed for immunohistochemical studies using a preembedding immunoperoxidase procedure. AQP-1 immunoreactivity was detected using affinity-purified rabbit polyclonal antibodies to AQP-1. AQP-1 was expressed throughout the arterial portion of the renal vasculature of the fetal and neonatal kidney from gestational age 17 days to 1 wk after birth. AQP-1 immunoreactivity gradually disappeared from the renal vasculature between 1 and 2 wk of age and remained only in the descending vasa recta. In contrast, AQP-1 immunoreactivity was not observed in lymphatic vessels until 3 wk of age and persisted in the adult kidney. AQP-1 was also expressed in a population of interstitial cells in the terminal part of the renal papilla at 3 wk of age as well as in the adult kidney. The transient expression of AQP-1 in the arterial portion of the renal vasculature in the developing rat kidney suggests that AQP-1 is important for fluid equilibrium and/or drainage in the developing kidney or, alternatively, plays a role in the regulation of growth and/or branching of the vascular tree during kidney development.

Aging↗

PubMed1999

Response of human tongue protrudor and retractors to hypoxia and hypercapnia.

It is well established that the genioglossus muscle (tongue protrudor) has a role in protecting or enhancing upper airway patency in individuals with obstructive sleep apnea. However, no investigation completed to date has addressed the role of the styloglossus and hyoglossus muscles (tongue retractors) in maintaining upper airway patency in humans. As a first step toward this goal, the present investigation was designed to examine the response of human tongue protrudor and retractor muscles during a breathhold maneuver and in steady-state hypoxic hypercapnia. The results showed that the protrudor and retractor muscles were coactivated under both conditions. Measurements of onset time of electromyographic activity during steady-state hypoxic hypercapnia revealed that phasic protrudor and retractor activity was initiated immediately before or during the early part of inspiration. We conclude that the tongue protrudor and retractor muscles are coactivated in response to hypoxia and hypercapnia, and that the tongue retractors may have a significant role in protecting upper airway patency during both apnea and hyperpnea.

Adult↗

PubMed1999

Gastrointestinal absorption of a new reversible proton pump inhibitor, YJA-20379-8, and its pharmacokinetics after oral administration in acetic acid-induced gastric ulcer in rats.

The absorption of YJA-20379-8 (3-butyryl-4-[5-(R)-(+)-methylbenzylamino]-8-ethoxy-1,7-naphthyrid ine) from various rat gastrointestinal segments was evaluated using in-situ closed-loops. The pharmacokinetics of the drug were also evaluated after oral administration to rats with acetic acid-induced gastric ulcer (AIURs). The concentrations of YJA-20379-8 in the biological samples were analyzed by HPLC. The absorption of YJA-20379-8 from stomach and jejunum was fast, but approximately 50% of the drug was recovered from each segment at 24 h. The total areas under the plasma concentration-time curves from time zero to 24h (AUC(0-24h)) were 161, 392, 233, 365, and 226 microg min mL(-1) for stomach, duodenum, jejunum, ileum, and colon, respectively. After oral administration of the drug, the plasma concentrations and the resultant AUC (0- 12h) were not significantly different between control and AIURs. The detection limits of YJA-20379-8 in human plasma and urine were 50 and 100 ng mL(-1), respectively. The results suggest that modification of the oral dose of YJA-20379-8 may not be required in gastric ulcer patients if the present rat pharmacokinetic data could be extrapolated to man.

Acetic Acid↗

PubMed1999

Gastrointestinal first-pass effect of YJA-20379-8, a new reversible proton pump inhibitor, in rats.

Since low bioavailability of YJA-20379-8 (3-butyryl-4-[5-R-(+)-methylbenzylamino]-8ethoxy-1,7-naph thy ridine), a new reversible proton pump inhibitor, has been reported after oral administration of the drug to rats, the first-pass organ of the drug was investigated in rats. YJA-20379-8, 50 mg kg(-1), was infused over 1 min via the jugular vein (n=5) or the portal vein (n=5), or was instilled directly into the stomach (n=5) or the duodenum (n=5). After intravenous or intraportal infusion of the drug, the total body clearance of YJA-20379-8 (18.1 and 19.7 mL min(-1) kg(- 1) based on plasma data) was considerably lower than the reported cardiac output (296 mL min(-1) kg(-1) based on blood data) in rats. This data indicated that the first-pass effect of YJA-20379-8 by the lung and heart was negligible. The areas under the plasma concentration-time curve from time zero to time infinity (AUC) after intravenous or intraportal administration of YJA-20379-8 (2760 and 2540 microg min mL(-1)) were not significantly different, indicating that the hepatic first-pass effect of the drug was also negligible in rats. After intragastric or intraduodenal instillation of YJA-20379-8, the extent of absolute oral bioavailability was 18.2 and 33.8%, respectively. Based on gastrointestinal recovery studies, approximately 86.5 and 91.2% of YJA-20379-8 was absorbed from rat gastrointestinal tract after intragastric or intraduodenal instillation, respectively. The data indicated that gastrointestinal and intestinal first-pass effects of YJA-20379-8 were approximately 68% (86.5-18.2) and 57% (91.2-33.8), respectively. The AUC(0-24h) values of YJA-20379-8 were significantly different between intragastric and intraduodenal instillation, indicating that the gastric first-pass effect of the drug was approximately 10% in rats. Therefore, it could be concluded that the low F value of YJA-20379-8 after oral administration of the drug could be due to a considerable (approx. 60%) intestinal first-pass effect in rats.

Animals↗

PubMed1999

Intercalated cell subtypes in connecting tubule and cortical collecting duct of rat and mouse.

At least two populations of intercalated cells, type A and type B, exist in the connecting tubule (CNT), initial collecting tubule (ICT), and cortical collecting duct (CCD). Type A intercalated cells secrete protons via an apical H+-ATPase and reabsorb bicarbonate by a band 3-like Cl-/HCO3-exchanger, AE1, located in the basolateral plasma membrane. Type B intercalated cells secrete bicarbonate by an apical Cl-/HCO3- exchanger that is distinct from AE1 and remains to be identified. They express H+-ATPase in the basolateral plasma membrane and in vesicles throughout the cytoplasm. A third type of intercalated cell with apical H+-ATPase, but no AE1, has been described in the CNT and CCD of both rat and mouse. The prevalence of the third cell type is not known. The aim of this study was to characterize and quantify intercalated cell subtypes, including the newly described third non A-non B cell, in the CNT, ICT, and CCD of the rat and mouse. A triple immunolabeling procedure was developed in which antibodies to H+-ATPase and band 3 protein were used to identify subpopulations of intercalated cells, and segment-specific antibodies were used to identify distal tubule and collecting duct segments. In both rat and mouse, intercalated cells constituted approximately 40% of the cells in the CNT, ICT, and CCD. Type A, type B, and non A-non B intercalated cells were observed in all of the three segments, with type A cells being the most prevalent in both species. In the mouse, however, non A-non B cells constituted more than half of the intercalated cells in the CNT, 39% in the ICT, and 22% in the CCD, compared with 14, 7, and 5%, respectively, in the rat. In contrast, type B intercalated cells accounted for only 8 to 16% of the intercalated cells in the three segments in the mouse compared with 26 to 39% in the rat. It is concluded that striking differences exist in the prevalence and distribution of the different types of intercalated cells in the CNT, ICT, and CCD of rat and mouse. In the rat, the non A-non B cells are fairly rare, whereas in the mouse, they constitute a major fraction of the intercalated cells, primarily at the expense of the type B intercalated cells.

Animals↗

PubMed1999

Functional characterization of the MODY1 gene mutations HNF4(R127W), HNF4(V255M), and HNF4(E276Q).

Genetic studies have shown that mutations in the gene encoding hepatocyte nuclear factor (HNF)-4alpha, a member of the steroid/thyroid hormone receptor superfamily, give rise to early-onset type 2 diabetes (MODY1). The functional properties of mutant HNF-4alpha proteins and the molecular mechanisms by which they impair insulin secretion are largely unknown. In the present study, we have investigated transcriptional activation, DNA binding properties, and protein dimerization activity of three HNF-4alpha missense mutations--HNF4(R127W), HNF4(V255M), and HNF4(E276Q)--that have been associated with type 2 diabetes. We demonstrate that HNF4(E276Q) has lost its ability to bind to HNF-4 consensus binding sites and activate transcription. HNF4(E276Q) had no effect on the functional activity of wild-type HNF-4alpha in the pancreatic beta-cell line HIT-T15, but it exhibited weak dominant-negative activity in other cell types. Analysis of HNF4(E276Q) protein showed that it exists in two forms: a full length 54-kDa protein and a 40-kDa COOH-terminal protein lacking the NH2-terminal transactivation domain and the DNA binding domain. Immunoprecipitation experiments indicate that this truncated protein can bind to wild-type HNF-4alpha and may be responsible for the weak dominant-negative effects seen in these cells. In addition, we show that the transcriptional transactivation of HNF4(R127W) and HNF4(V255M) is indistinguishable from that of wild-type HNF-4alpha, suggesting that they are sequence polymorphisms. Our results demonstrate that HNF4(E276Q) is a loss-of-function mutation and that it identifies glutamic acid 276 in alpha-helix 8 of the ligand-binding domain of HNF-4alpha protein as a critical residue for DNA binding, transcriptional activation, and protein stability in vivo.

Animals↗

PubMed1999

Organization and sequences of p-hydroxybenzaldehyde dehydrogenase and other plasmid-encoded genes for early enzymes of the p-cresol degradative pathway in Pseudomonas putida NCIMB 9866 and 9869.

The gene (designated pchA) encoding the aldehyde dehydrogenase that is required to metabolise the p-hydroxybenzaldehyde produced by the degradation of p-cresol in Pseudomonas putida NCIMB 9866 and 9869 has been identified on plasmids pRA4000 and pRA500, respectively. The gene lies immediately upstream of the pchC and pchF genes encoding the subunits of p-cresol methylhydroxylase (PCMH), the preceeding enzyme in the p-cresol degradative pathway. In pRA500 the latter genes are followed by the genes encoding the alpha (pcaG) and beta (pcaH) subunits of protocatechuate-3,4-dioxygenase, whereas in pRA4000 the genes encoding PCMH are followed by an open reading frame encoding a protein that is similar to the maturase-related protein of P. alcaligenes. A gene, designated pchX, that encodes a protein of unknown function was identified between the pchC and pchF genes in both plasmids.

Aldehyde Oxidoreductases↗

PubMed1999

Rapid and easy detection of Helicobacter pylori by in situ hybridization.

Various in situ hybridization (ISH) methods have been used to identify Helicobacter pylori, a causative organism responsible for chronic gastritis and peptic ulcer disease, but they were hard to perform and time consuming. To detect H. pylori in a rapid and easily reproducible way, we developed synthetic biotinylated oligonucleotide probes which complement rRNA of H. pylori. Formalin-fixed and paraffin-embedded tissues from 50 gastric biopsy specimens were examined. Using a serologic test and histochemical stain (Warthin-Starry silver stain and/or Giemsa stain) as a standard, 40 of them were confirmed to be H. pylori-positive. Our ISH was quickly carried out within one hr and results were compared with those obtained from immunohistochemical stain. The ISH produced a positive reaction in 38 of 40 cases (95%). All H. pylori-negative cases failed to demonstrate a positive signal. The ISH has a sensitivity comparable to those of conventional histochemical and immunohistochemical stain, and has high specificity. In conclusion, ISH with a biotinylated oligonucleotide probe provides a useful diagnostic method for detecting H. pylori effectively in routinely processed tissue sections.

Helicobacter Infections↗

PubMed1999

Role of tissue inhibitors of metalloproteinases (TIMPs) in colorectal carcinoma.

Increased production of matrix metalloproteinases (MMPs) has been associated with increases in invasive and metastatic potential in many types of human carcinoma. Tissue inhibitors of metalloproteinase (TIMP)-1 inhibits most interstitial collagenases and MMP-9. TIMP-2 binds specifically and noncovalently to the pro-form of MMP-2 and inhibits its enzyme activity. In this study, we examined TIMP-1 and TIMP-2 expressions in relation to clinicopathological variables in colorectal carcinoma with in situ hybridization and immunohistochemistry. TIMP-1 and TIMP-2 expressions were localized overwhelmingly to pericancer stromal cells, while malignant and normal mucosal cells were weak or negative. Strong stromal TIMP-1 immunoreactivity correlated with Dukes' stage (p=0.022), status of lymph node metastasis (p=0.044) and poor survival (p= 0.005). The degree of immunohistochemical staining of TIMP-2 did not correlate with all clinicopathological variables. The correlation between enhanced TIMP-1 expression and advanced stage and poor survival suggest a growth promoting activity of TIMP-1 in colorectal carcinoma.

Adenocarcinoma↗

PubMed1999

Variation of antigenicity and serological reaction to Pneumocystis carinii in Korea.

The present study observed the variation of antigenicity of Pneumocystis carinii and serum IgG antibody reaction to the antigens from different localities in Korea. Antigens of rat P. carinii and sera of inhabitants were collected at Chunchon. Chungju, Kwangju, and Seoul during 1995-1996. Enzyme-linked Immunosorbent Assay and immunoblot were used for immune reaction. Absorbance of 1,294 human sera ranged between 0.01 and 0.93. Sera from Chunchon showed higher absorbances than those from other areas. Immunoblotting revealed IgG antibody reactions to 116, 100, and 45-55 kDa antigenic bands of rat P. carinii, but the frequencies of positive reaction to individual bands were variable by localities. Total 62.6% of the sera showed the reaction to 116 kDa band while 37.7% reacted to 100 kDa band and 32.0% to 45-55 kDa bands. For the reaction to 116 kDa, the reaction rate was 60.0% to 82.6% by localities. It is found that the reaction rates of the human sera to rat P. carinii antigen are variable according to the localities. Also, the high molecular antigen of 116 kDa of rat P. carinii is the most frequent antigenic band reacting to human sera.

Animals↗

PubMed1999

Is Pneumocystis carinii vertically transmitted to neonatal rats?

Pneumocystis carinii is a pulmonary pathogen of immunocompromised humans or other mammals. Its infection results from activation of organisms involved in latent infection or from new infection through the air. Almost all children are known to be infected within 2 to 4 years of birth, though prenatal transplacental transmission has not yet been demonstrated. In this study we observed experimental P. carinii infection in neonatal rats, thus investigating the possibility of transplacental vertical transmission by Diff-Quik staining of the lung impression smears and in-situ hybridization for lung sections. The positive rate of P. carinii infection in immunosuppressed maternal rats was 100%, but that in normal maternal rats was 0%. Cystic forms of P. carinii were observed in three of six 1-week old neonatal rats born of heavily infected mothers, but none of them was positive by in-situ hybridization. Five weeks after birth, cystic forms were detected in four neonatal rats. In the lobes of the lungs, no predilection site of P. carinii was recognized. Counts of cystic forms on smears and the reactivity of in-situ hybridization in the lungs of neonatal rats were significantly lower than in maternal rats. The present findings suggest that P. carinii is rarely transmitted through the placenta and proliferates less successfully in the lungs of neonatal rats than in mothers.

Animals↗

PubMed1999

Behavioral, toxic, and neurochemical effects of sydnocarb, a novel psychomotor stimulant: comparisons with methamphetamine.

Sydnocarb (3-(beta-phenylisopropyl)-N-phenylcarbamoylsydnonimine) is a psychostimulant in clinical practice in Russia as a primary and adjunct therapy for a host of psychiatric disorders, including schizophrenia and depression. It has been described as a stimulant with an addiction liability and toxicity less than that of amphetamines. The present study undertook to evaluate the psychomotor stimulant effects of sydnocarb in comparison to those of methamphetamine. Sydnocarb increased locomotor activity of mice with reduced potency (approximately 10-fold) and efficacy compared with methamphetamine. Sydnocarb blocked the locomotor depressant effects of haloperidol at doses that were inactive when given alone. The locomotor stimulant effects of both methamphetamine and sydnocarb were dose-dependently blocked by the dopamine D1 and D2 antagonists SCH 39166 and spiperone, respectively; blockade generally occurred at doses of the antagonists that did not depress locomotor activity when given alone. In mice trained to discriminate methamphetamine from saline, sydnocarb fully substituted for methamphetamine with a 9-fold lower potency. When substituted for methamphetamine under self-administration experiments in rats, 10-fold higher concentrations of sydnocarb maintained responding by its i.v. presentation. Sydnocarb engendered stereotypy in high doses with approximately a 2-fold lower potency than methamphetamine. However, sydnocarb was much less efficacious than methamphetamine in inducing stereotyped behavior. Both sydnocarb and methamphetamine increased dialysate levels of dopamine in mouse striatum; however, the potency and efficacy of sydnocarb was less than methamphetamine. The convulsive effects of cocaine were significantly enhanced by the coadministration of nontoxic doses of methamphetamine but not of sydnocarb. Taken together, the present findings indicate that sydnocarb has psychomotor stimulant effects that are shared by methamphetamine while demonstrating a reduced behavioral toxicity.

Animals↗

PubMed1999

Known mutations of apoB account for only a small minority of hypobetalipoproteinemia.

Low LDL cholesterol and apoB levels in plasma cosegregate with mutations of apoB in some kindreds with familial hypobetalipoproteinemia. Approximately 35 apoB mutations, many specifying apoB truncations, have been described. Based on the centile nomenclature where the full-length nature apoB consisting of 4536 amino acids is designated as apoB-100, only those truncations of apoB >25% of normal length are detectable in plasma. Previously, we reported on five unrelated kindreds with familial hypobetalipoproteinemia in whom although no apoB truncations were detectable in plasma, low apoB levels were nevertheless linked to the apoB gene. In one of those kindreds, we reported a donor splice site mutation in intron 5 (specifying apoB- 4). We now describe a nonsense mutation in exon 10 (apoB-9) in two of the other unrelated families. Both the apoB-4 and apoB-9 mutations have been reported by others in unrelated families. Recurrent mutations of apoB-40 and apoB-55 also have been reported, suggesting that recurrent mutations of apoB may account for an appreciable proportion of familial hypobetalipoproteinemia kindreds. To test this hypothesis, we searched for four apoB mutations whose products are not detected in plasma including the apoB-4, apoB-9, and two other previously reported mutations in exons 21 and 25. We studied three groups with plasma cholesterols <130 mg/dl in whom no apoB truncations were detected in plasma: a) 28 FHBL probands from St. Louis, b) 151 individual St. Louisians, and c) 28 individual Sicilians. One subject from the 28 kindreds and two subjects among 151 hypobeta individuals from St. Louis harbored the exon 10 mutation. None of the other mutations were detected. Thus, among hypobeta lipoproteinemic subjects without any detectable apoB truncations in plasma, <5% had an apoB truncation-producing mutation. As only about 0.5% of hypobeta lipoproteinemic subjects have plasma-detectable apoB truncations, our data suggest that the known apoB truncations account for only a small proportion of hypocholesterolemia.

Apolipoproteins B↗

PubMed1999

Thickness distribution of the occipital bone--a new approach based on CT-data of modern humans and OH 9 (H. ergaster).

A new approach for the analysis of cranial bone thickness is introduced. The study focuses on the occipital bone of modern humans and of a 1.25 Myr-old H. Ergaster/erectus specimen from Olduvai Gorge (OH 9). A semiautomatic algorithm detects a multitude of thicknesses from CT-data of the investigated bones. We find that every bone is characterized by its own distribution pattern of cranial thickness, which is then analyzed statistically. The results demonstrate that the thickness distribution of the occipital bone of OH 9 is within the normal range of the H. sapiens sample (which itself shows a remarkably high variance). This contributes to a further analysis of phyletic differences of hominid morphology by including distribution patterns of thickness combined with aspects of functional anatomy.

Algorithms↗

PubMed1998

The Vestigial and Scalloped proteins act together to directly regulate wing-specific gene expression in Drosophila.

A small number of major regulatory (selector) genes have been identified in animals that control the development of particular organs or complex structures. In Drosophila, the vestigial gene is required for wing formation and is able to induce wing-like outgrowths on other structures. However, the molecular function of the nuclear Vestigial protein, which bears no informative similarities to other proteins, was unknown. Here, we show that Vestigial requires the function of the Scalloped protein, a member of the TEA family of transcriptional regulators, to directly activate the expression of genes involved in wing morphogenesis. Genetic and molecular analyses reveal that Vestigial regulates wing identity by forming a complex with the Scalloped protein that binds sequence specifically to essential sites in wing-specific enhancers. These enhancers also require the direct inputs of signaling pathways, and the response of an enhancer can be switched to another pathway through changes in signal-transducer binding sites. Combinatorial regulation by selector proteins and signal transducers is likely to be a general feature of the tissue-specific control of gene expression during organogenesis.

Animals↗

PubMed1998

Isolated human germinal center centroblasts have an intact mismatch repair system.

Ig somatic hypermutation contributes to the generation of high-affinity Abs that are essential for efficient humoral defense. The presence of multiple point mutations in rearranged Ig V genes and their immediate flanking sequences suggests that the DNA repair system may not be working properly in correcting point mutations introduced to the restricted region of Ig genes. We examined the DNA repair functions of germinal center (GC) centroblasts, which are the cells in which ongoing Ig hypermutation takes place. We found that GC centroblasts express all known components of the human DNA mismatch repair system, and that the system corrects DNA mismatches in a strand-specific manner in vitro. We conclude that general suppression of mismatch repair at the cellular level does not occur during somatic hypermutation.

B-Lymphocytes↗

PubMed1998

Isolation and characterization of mammalian homologs of the Drosophila gene glial cells missing.

The glial cells missing (gcm) gene in Drosophila encodes a transcription factor that determines the choice between glial and neuronal fates. We report here the isolation of two mammalian gcm homologs, Gcm1 and Gcm2, and the characterization of their expression patterns during embryonic development. Although Gcm2 is expressed in neural tissues at a low level, the major sites of expression for both of the mammalian genes are nonneural, suggesting that the functions of the mammalian homologs have diverged and diversified. However, when expressed ectopically, Gcm1 can substitute functionally for Drosophila gcm by transforming presumptive neurons into glia. Thus, certain biochemical properties, although not the specificity of the tissue in which the gene is expressed, have been conserved through the evolution of the Gcm gene family.

Amino Acid Sequence↗