PubMed Health⌕ Search

Biomedical subjects

H Sakano

Publications and source records attributed to H Sakano.

At least 37 records · Page 2Linked to original sources
PubMed2000

The DNA-bending protein, HMG1, is required for correct cleavage of 23 bp recombination signal sequences by recombination activating gene proteins in vitro.

DNA-bending proteins are known to facilitate the in vitro V(D)J joining of antigen receptor genes. Here we report that the high-mobility group protein, HMG1, is necessary for the correct nicking of the 23 bp recombination signal sequence (23-RSS) by the recombination [corrected] activating gene (RAG) proteins, RAG1 and RAG2. Without HMG1, the mouse Jkappa1 23-RSS was recognized as if it were the 12-RSS and nicked at a site 12 + 7 nucleotides away from the 9mer signal, even though no 7mer-like sequence was evident at the cryptic nicking site. When increased amounts of HMG1 were added, the 23-RSS substrate was nicked correctly at a site 23 + 7 nucleotides from the 9mer, and nicking at the cryptic site disappeared. Unlike the 23-RSS, the 12-RSS did not require HMG1 for correct nicking, although HMG1 was found to increase the interaction between RSS and RAG proteins. Modification-interference assays demonstrated that HMG1 caused changes in the interaction between the 23-RSS and RAG proteins specifically at the 7mer and the cryptic nicking site.

Animals↗
PubMed1999

Olfactory neurons expressing closely linked and homologous odorant receptor genes tend to project their axons to neighboring glomeruli on the olfactory bulb.

We have characterized two separate odorant receptor (OR) gene clusters to examine how olfactory neurons expressing closely linked and homologous OR genes project their axons to the olfactory bulb. Murine OR genes, MOR28, MOR10, and MOR83, share 75-95% similarities in the amino acid sequences and are tightly linked on chromosome 14. In situ hybridization has demonstrated that the three genes are expressed in the same zone, at the most dorsolateral and ventromedial portions of the olfactory epithelium, and are rarely expressed simultaneously in individual neurons. Furthermore, we have found that olfactory neurons expressing MOR28, MOR10, or MOR83 project their axons to very close but distinct subsets of glomeruli on the medial and lateral sides of the olfactory bulb. Similar results have been obtained with another murine OR gene cluster for A16 and MOR18 on chromosome 2, sharing 91% similarity in the amino acid sequences. These results may indicate an intriguing possibility that olfactory neurons expressing homologous OR genes within a cluster tend to converge their axons to proximal but distinct subsets of glomeruli. These lines of study will shed light on the molecular basis of topographical projection of olfactory neurons to the olfactory bulb.

Amino Acid Sequence↗
PubMed1999

Multiple gigantic arteriovenous malformations with destruction of lumbar vertebral bodies. A case report.

STUDY DESIGN: This case report describes a patient with massive intramuscular and paravertebral arteriovenous malformations with destruction of vertebral bodies. OBJECTIVES: To demonstrate successful interbody fusion of the involved vertebral bodies after embolization for arteriovenous malformation. SUMMARY OF BACKGROUND DATA: Although arteriovenous malformations in the spinal cord are well documented in the literature, arteriovenous malformation in the paravertebral and iliopsoas muscles with destruction of vertebral bodies is an extremely rare clinical condition. METHODS: After careful investigation with angiography, the arteriovenous malformations were managed with embolization, and the scoliosis caused by the collapsed vertebral bodies was managed surgically by anterior spinal fusion with segmental spinal instrumentation. RESULTS: The patient's scoliosis caused by vertebral collapse was corrected by surgery, and good alignment of the lumbar spine was achieved. The preoperation pain had subsided completely by follow-up assessment 1 year and 10 months after fusion. However, the arteriovenous malformations still remained. Careful observation should be maintained continuously in the coming days. CONCLUSION: In arteriovenous malformations with destruction of the vertebral bodies, embolization and spinal fusion with segmental instrumentation may be necessary to relieve pain and prevent the progression of spinal deformity. Arteriovenous malformation should be considered in the diagnostic evaluation of a patient who has experienced vertebral collapse with no inflammatory signs.

Adult↗
PubMed1999

Functional identification and reconstitution of an odorant receptor in single olfactory neurons.

The olfactory system is remarkable in its capacity to discriminate a wide range of odorants through a series of transduction events initiated in olfactory receptor neurons. Each olfactory neuron is expected to express only a single odorant receptor gene that belongs to the G protein coupled receptor family. The ligand-receptor interaction, however, has not been clearly characterized. This study demonstrates the functional identification of olfactory receptor(s) for specific odorant(s) from single olfactory neurons by a combination of Ca2+-imaging and reverse transcription-coupled PCR analysis. First, a candidate odorant receptor was cloned from a single tissue-printed olfactory neuron that displayed odorant-induced Ca2+ increase. Next, recombinant adenovirus-mediated expression of the isolated receptor gene was established in the olfactory epithelium by using green fluorescent protein as a marker. The infected neurons elicited external Ca2+ entry when exposed to the odorant that originally was used to identify the receptor gene. Experiments performed to determine ligand specificity revealed that the odorant receptor recognized specific structural motifs within odorant molecules. The odorant receptor-mediated signal transduction appears to be reconstituted by this two-step approach: the receptor screening for given odorant(s) from single neurons and the functional expression of the receptor via recombinant adenovirus. The present approach should enable us to examine not only ligand specificity of an odorant receptor but also receptor specificity and diversity for a particular odorant of interest.

Adenoviridae↗
PubMed1999

Prf, a novel Ets family protein that binds to the PU.1 binding motif, is specifically expressed in restricted stages of B cell development.

During the development of lymphocytes, expression of the Ig genes is strictly regulated in a tissue-specific manner and in a time-ordered fashion. We have previously shown that the PU.1 binding motif in the Igkappa 3' enhancer (kappaE3') and a novel Ets family protein other than PU.1 may be possibly involved in the control of V(kappa)-J(kappa) joining. In the attempt to isolate the novel Ets family protein, we have screened cDNA libraries with the yeast one-hybrid method and identified a new PU.1-related factor, Prf. This novel Ets family protein is shown to interact with the PU.1 binding sequences in various promoters and enhancers, including kappaE3'. It was found that expression of the prf gene is predominant in the B-lineage cells, with the exception of immature B cells. Since Prf does not exhibit functions of transcriptional activity, this novel protein may act as an antagonist against other Ets family proteins, e.g. PU.1 and Spi-B. Possible roles of Prf with respect to the B cell differentiation are discussed.

Amino Acid Sequence↗
PubMed1998

Footprint analysis of the RAG protein recombination signal sequence complex for V(D)J type recombination.

We have studied the interaction between recombination signal sequences (RSSs) and protein products of the truncated forms of recombination-activating genes (RAG) by gel mobility shift, DNase I footprinting, and methylation interference assays. Methylation interference with dimethyl sulfate demonstrated that binding was blocked by methylation in the nonamer at the second-position G residue in the bottom strand and at the sixth- and seventh-position A residues in the top strand. DNase I footprinting experiments demonstrated that RAG1 alone, or even a RAG1 homeodomain peptide, gave footprint patterns very similar to those obtained with the RAG1-RAG2 complex. In the heptamer, partial methylation interference was observed at the sixth-position A residue in the bottom strand. In DNase I footprinting, the heptamer region was weakly protected in the bottom strand by RAG1. The effects of RSS mutations on RAG binding were evaluated by DNA footprinting. Comparison of the RAG-RSS footprint data with the published Hin model confirmed the notion that sequence-specific RSS-RAG interaction takes place primarily between the Hin domain of the RAG1 protein and adjacent major and minor grooves of the nonamer DNA.

Animals↗
PubMed1998

Lung volume reduction surgery for pulmonary emphysema using dynamic Xenon-133 and Tc-99m-MAA SPECT images.

The usefulness of Xe-133 and Tc-99m-MAA single photon emission computed tomography (SPECT) in identifying areas to be resected during video-assisted thoracoscopic lung reduction surgery for emphysema was examined. Twenty-nine patients with advanced emphysema were examined using Xe-133 and Tc-99m-MAA SPECT prior to and following surgery. For the Xe-133 dynamic SPECT, patients inhaled Xe-133 gas for 6 minutes. Equilibrium and subsequent washout SPECT images were acquired every 30 seconds for 6 to 7 minutes during spontaneous breathing. Ventilation was quantified by Xe-133 clearance time (T1/2) in addition to visual assessment. The patients underwent unilateral thoracoscopic volume reduction in the regions with abnormal Xe-133 retention and Tc-99m-MAA defect. All patients demonstrated marked, heterogeneous Xe-133 retention and Tc-99m-MAA defects preoperatively. The worst functioning areas were identified as nonventilated and noflow areas, or areas with air trapping and low perfusion. These changes were found even in patients with diffuse and symmetrical impairments on chest CT. After surgery, most of these "target areas" disappeared and pulmonary function tests demonstrated significant improvement. T1/2 correlated closely with the percent predicted FEV1 (%FEV) and 6-minute walk distance before and after surgery (p<0.0001). Xe-133 and Tc-99m-MAA SPECT imaging was useful in identifying "target areas" in the emphysematous lung. Directed unilateral thoracoscopic volume reduction based on these SPECT images is an effective treatment for emphysema.

Aged↗
PubMed1997

The PU.1 binding site is a cis-element that regulates pro-B/pre-B specificity of Vkappa-Jkappa joining.

We have previously shown that the PU.1 binding motif (GAG GAA) in the 3'-enhancer region in the Ig kappa gene is responsible for the negative regulation of tissue (B/T)-specific Vkappa-Jkappa joining. Here we report that the PU.1 binding site also regulates the stage (pro-B/pre-B) specificity of Vkappa-Jkappa joining. In the substrate with base substitutions in the PU.1 binding motif, recombination took place in both pro-B (B220dull/CD43+) and pre-B (B220dull/CD43-) cells. In the transcriptional regulation, the PU.1 motif acts in a positive manner cooperatively with the nuclear factor-EM5 (or PIP) motif (GAAAAC), which is located 2 bp downstream from the PU.1 motif. Interestingly, base substitutions in the nuclear factor EM5 (PIP) motif did not affect the pro-B/pre-B specificity of Vkappa-Jkappa joining. Thus, the PU.1 motif regulates both temporal and tissue-specific rearrangements, while nuclear factor-EM5 is not involved in the regulation of Ig kappa recombination.

Animals↗
PubMed1996

Genomic structure and transcription of a murine odorant receptor gene: differential initiation of transcription in the olfactory and testicular cells.

We have characterized genomic structure and transcription of a murine odorant receptor (OR) gene, MOR23. This gene has two distinct transcriptional initiation regions, which are differentially utilized in the olfactory and testicular cells. We have found that the MOR23 gene has an intron within the 5'-untranslated region upstream of the coding sequence. In olfactory cells, transcription of the gene is initiated in the region upstream of this intron, while in testicular cells, transcription starts within the intron. Differential initiation of transcription is discussed in the context of tissue-specific expression of the OR genes.

Animals↗
PubMed1996

Effect of polyol fatty acid esters on diclofenac permeation through rat skin.

The effects of a series of polyol fatty acid esters (sefsols) on diclofenac permeation through rat skin were investigated using in vitro and in vivo methods. Four monoesters and one diester of sefsol were selected as a vehicle components. The effects of each sefsol on in vitro diclofenac permeation were compared at a concentration of 5% sefsol in water. Monoesters of sefsol, except the glyceryl monoester, enhanced the percutaneous permeation of diclofenac. The highest enhancement was observed in propylene glycol monocaprylate. The plasma concentration of diclofenac was increased dramatically by the addition of 10% propylene glycol monocaprylate when applying the diclofenac sodium suspension to abdominal rat skin in vivo. These results suggest that the monoesters of polyol fatty acid are potential candidates to enhance the transdermal absorption of diclofenac sodium.

Administration, Cutaneous↗
PubMed1995

The 3' enhancer region determines the B/T specificity and pro-B/pre-B specificity of immunoglobulin V kappa-J kappa joining.

Using transgenic substrates, we found that the immunoglobulin kappa gene 3' enhancer (E3') acts as a negative regulator in V kappa-J kappa joining. Although the E3' was originally identified as a transcriptional enhancer, it acts in a suppressive manner for recombinational regulation. Base substitution analysis has shown that the PU.1-binding site within the E3' regulates the B/T specificity of V kappa-J kappa joining. In a substrate with a mutated PU.1-binding site (GAGGAA to TCTTCG), V kappa-J kappa joining occurred not only in B cells, but also in T cells. The E3' region is also responsible for determining the pro-B/pre-B specificity of V kappa-J kappa joining. When the E3' region was deleted, kappa gene rearrangement actively occurred at the early pro-B stage of B cell development: nongermline (N) nucleotides were common at recombination junctions.

Animals↗
PubMed1995

Effects of the ester moiety on stereoselective hydrolysis of several propranolol prodrugs in rat tissues.

The stereochemical characteristics of the hydrolysis of several ester-type prodrugs of propranolol, O-acetyl, O-propionyl, O-butyryl, O-pivaloyl and succinyl esters, were studied in phosphate buffer (pH 7.4), rat plasma and rat tissue homogenates. In phosphate buffer, no differences were observed in the hydrolysis rate between the esters of (R)- and (S)-propranolol. The effects of the ester moieties on the hydrolysis rate in phosphate buffer were in the following order: acetate > propionate > butyrate > succinate > pivalate. In rat plasma and tissue homogenates, the hydrolysis of the esters was accelerated, and stereoselective hydrolysis was observed. In plasma, the hydrolysis of the (R)-isomer was faster than that of the (S)-isomer except for the succinate ester. On the other hand, in the liver and intestine homogenates, the (S)-isomer was hydrolyzed faster than the (R)-isomer except for the succinate and pivalate esters in the liver homogenate. Also, the ratio of the hydrolysis rates (S/R) changed with the type of prodrug. As the length of the alkyl chain of the ester increased, the S/R ratio approached unity in liver and intestine homogenates but stayed almost constant in plasma. For the pivalate ester, stereoselective hydrolysis was observed in plasma and intestine homogenate but not in liver homogenate. The stereoselective hydrolysis of the succinate ester was observed only in intestine homogenate, but the S/R ratio was almost 1 in plasma, liver and intestine homogenates. No interconversion between (R)- and (S)-isomer was observed during the hydrolysis of any of the ester prodrugs. These results indicate that hydrolysis of ester-type prodrugs of propranolol occurs stereoselectively in rat tissues, and that its selectivity is dependent on the kind of tissue and prodrug.

Adrenergic beta-Antagonists↗
PubMed1995

Effect of vehicles on diclofenac permeation across excised rat skin.

The in vitro percutaneous permeation of diclofenac from various vehicles was examined using rat abdominal skin as a model membrane. The oleaginous vehicles used in this study consisted of three components: i.e. fatty acid, fatty acid ester and nonpolar oil. The solubilities of sodium diclofenac in formulated vehicles were above 0.2 M. The effect of each oleaginous component in the vehicle on the permeation of diclofenac across the skin was in the following order: oleic acid > isostearic acid, diisopropyl adipate = diethyl sebacate > Panasate 875 and squalane > liquid paraffin. To clarify the reason for the differences in permeation among the fatty acid esters, the release of diclofenac through either porous or lipoidal membranes from these vehicles in vitro and the solubility of sodium diclofenac in the vehicles were studied. However, no relationship was observed between the release rate or solubility and skin permeability. The skin permeation of diclofenac increased following pretreatment with diisopropyl adipate or diethyl sebacate, but not with middle chain triglyceride (Panasate 875). These results suggested that the main reason may be the enhancement effect of fatty acid esters. Emulsions and creams containing 3% sodium diclofenac were prepared using the above oleaginous vehicles. A large flux and short lag time were observed in these preparations compared with an aqueous suspension of sodium diclofenac. The incorporation of urea significantly enhanced the permeation of diclofenac from these preparations. These results suggest that the emulsion and cream prepared in this study are useful for development for practical purposes.

Animals↗
PubMed1995

[Electrophysiologic evaluation of entrapment neuropathy caused by scar formation in recurrent motor branch of the median nerve].

A unique case of mononeuropathy was encountered in a 20-year-old man with isolated involvement of the recurrent motor branch of the right median nerve following a skiing accident one year previously. There was also isolated involvement of the right thenar muscles innervated by the median nerve. Sensation was intact in the right hand and fingers. Conventional conduction studies in the right median nerve yielded no abnormal findings except a reduction in the amplitude of the muscle action potential. However, insertion of a needle electrode into the abductor pollicis brevis muscle revealed some delayed motor unit potentials following electrical stimulation at the wrist. We performed surgery and found the right recurrent motor branch to be entrapped by fibrous scar tissue 3 to 4 mm distal to branching from the median nerve. Direct recordings made from the nerve trunk using a tungsten microelectrode with supramaximal stimulation at the elbow revealed reduced amplitude of the compound nerve action potential distal to the site of entrapment. We concluded that scar tissue resulting from the previous injury had compressed the recurrent motor branch, causing this unique neuropathy.

Adult↗