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Biomedical subjects

K Maekawa

Publications and source records attributed to K Maekawa.

At least 19 recordsLinked to original sources
PubMed1992

The cDNA cloning and mRNA expression of rat protein C.

We cloned a cDNA coding for rat protein C, which provides hybridization probes for the detection of protein C mRNA in several tissues. The cloned cDNA was 1543 bp long and contained a single open reading frame of 1383 nucleotides. The proposed rat protein C precursor contained 461 amino acid residues: a 41 amino acid preproleader sequence, and light (155 amino acids) and heavy (263 amino acids) chains joined by a Lys-Arg dipeptide. Northern blot analysis showed that the rat protein C mRNA was expressed not only in the liver, but also in the kidney.

Amino Acid Sequence↗
PubMed1992

Determination of the sequence coding for the beta subunit of the human high-affinity IgE receptor.

The cDNA encoding the beta subunit of the human high-affinity IgE receptor was cloned by a combination of various polymerase chain reactions (PCR). A major portion of the beta cDNA was amplified using primers homologous within the sequences of rat and mouse. The 3' unknown sequence was preferentially amplified using the RNA template-specific PCR and the improved two-step PCR. The 5' unknown sequence was specifically amplified by our newly developed PCR walking. Random heptanucleotides tagged with a unique sequence at the 5' end were used as the walking primer. Finally, the entire coding region was amplified and sequenced. The two extracellular loops of the human beta subunit were the least homologous to those of rat and mouse.

Amino Acid Sequence↗
PubMed1992

Rapid identification of mutations in the glucocerebrosidase gene of Gaucher disease patients by analysis of single-strand conformation polymorphisms.

To detect mutations in the glucocerebrosidase gene in Gaucher disease patients, we used the recently described technique of single-strand conformation polymorphism (SSCP) analysis in combination with selective amplification. We analyzed exon 8, 9, 10 and 11 of the glucocerebrosidase gene; these exons were sequentially amplified using the selectively amplified products as templates. We found variant SSCP patterns corresponding to the presence or absence of the 6433C mutation, which was detected by NciI digestion analysis, in exon 10. Furthermore, we detected four variant SSCP patterns in exon 8, 10 and 11. Sequencing analysis consistently revealed four single-base substitutions in the corresponding exons, three novel missense mutations (5409A, 6375G and 6682T) and one silent polymorphism (6594A). These mutations were found only in one patient; therefore, these findings have confirmed the marked genetic heterogeneity of Gaucher disease. SSCP analysis in combination with selective amplification is a rapid and sensitive procedure for the screening of the mutations in the glucocerebrosidase gene of patients with Gaucher disease.

Base Sequence↗
PubMed1992

Establishment and characteristics of a T-cell acute lymphoblastic leukemia cell line, JK-T1, with a chromosomal translocation between 8q24 and 14q13.

A human leukemia cell line, JK-T1, was established from the bone marrow of a 10-year-old boy with T-cell acute lymphoblastic leukemia. The origin of the leukemic cell line, JK-T1, was demonstrated by its chromosomal and immunologic similarity to the patient's fresh leukemic cells. Karyotypic analysis revealed 46,XY,del(6)(q?),t(8;14)(q24;q13),der(9)t(9;?)(q34;?). In JK-T1, neither rearrangement nor amplification of the c-myc gene was observed apparently because the breakpoint of chromosome 14 was not q11 but q13. JK-T1 was independent of interleukin 2 (IL-2) because of little production of IL-2, little IL-2 receptor (CD25) on the surface, and no response to exogenous IL-2. JK-T1 had lymphocyte function associated antigen-1 (LFA-1) (CD11a, CD18) on its surface and could adhere to the hematologic stromal layer. These characteristics of JK-T1 cell line are considered to be useful not only for evaluating the role of t(8;14) but also in studying the adhesion molecules of leukemia.

Bone Marrow Cells↗
PubMed1992

A straight correlation between mutagenic activity and beta-galactosidase activity induced by monofunctional alkylating agents.

Eight monofunctional alkylating agents were examined for their ability to induce mutation in Salmonella typhimurium. The assay was carried out in S. typhimurium TA100 with the preincubation method. The SN1-type agents were more mutagenic than the SN2-type ones; besides, methylating agents exerted more mutagenic activity than ethylating ones. Those responses in the reversion assay were quite similar to the results obtained previously with the beta-galactosidase assay in Escherichia coli CSH26/pMCP1000 (alkA'-lacZ') as to the induction of the adaptive response. A good correlation was found between mutagenic potency in the reverse mutation assay and inducing potency in the beta-galactosidase assay.

Alkylating Agents↗
PubMed1992

Transient, unilateral, isolated hypoglossal nerve palsy.

We report a boy with isolated hypoglossal nerve palsy that recovered within twelve weeks. Investigations of the cervix, base of the skull, medulla and hypoglossal nerve by CT-scan and MRI did not show any abnormal findings. There are a few reports concerning isolated unilateral hypoglossal nerve palsy with benign course. Although we could not establish the cause of our patient's disease, an awareness of this condition should save such patients from unnecessary invasive studies.

Child↗
PubMed1992

BUN/Cr ratio as an index of gastrointestinal bleeding mass in children.

Determining the site and severity of blood loss is important in the management of children with gastrointestinal (GI) bleeding. Blood urea nitrogen (BUN) and serum creatinine (Cr) were measured on the day of hospitalization and the ratio of BUN/Cr was calculated in 11 children with 16 episodes of upper GI bleeding and 49 with lower GI bleeding. There was a significant difference between the two GI bleeding groups with regard to BUN/Cr ratio (p less than 0.001). When the ratio was 30 or above, the specificity of upper GI bleeding was 98% with a sensitivity of 68.8%. A linear relationship was found between the BUN/Cr ratio and delta Hb (delta Hb = 0.08 x BUN/Cr +/- 0.8 g/dl) for bleeding originating from the upper GI tract. This study confirms that measurement of the BUN/Cr ratio is useful for localizing the source of bleeding to the upper GI tract and also demonstrates its usefulness as an estimation of the severity of blood loss from the upper GI tract.

Adolescent↗
PubMed1992

[A patient with epilepsy presenting developmental regression after seizures--consideration of the mechanism from the findings of CT-scan and SPECT].

We report a 6-month-old female infant with frequent brief seizures who subsequently showed developmental regression. CT-scans right after her seizures revealed enlargement of bilateral subdural space more on the right side with an evidence to suggest destruction of the blood brain barrier in enhanced CT-scan, CT-scan, one month after the onset, showed diffuse brain atrophy. 123I-SPECT, which was performed 11 days after cessation of her seizures, still showed diffuse hypoperfusion predominantly in the right temporal area, and it returned to normal 3 months after the onset. We discussed the mechanisms of developmental regression in this case from the neuroradiological findings.

Child, Preschool↗
PubMed1992

[A clinical course and autopsy results of an 8-year-old severely handicapped girl with marked periventricular leukomalacia].

We reported a clinical course and autopsy results of an 8-year-old severely handicapped girl with marked periventricular leukomalacia. She was well until 3 days prior to first admission in local hospital. Two days prior to admission, she began to vomit. Twelve hours later, she was noted to be lethargic and developed malaise with frequent vomiting. At physical examination on admission, she had frequent fits and her posture was decerebrate rigidity. Consciousness disturbance continued for two weeks. Thereafter, she became severely handicapped with spastic quadriplegia, mental retardation and intractable epilepsy. She was transferred to our hospital one month later. We cared her totally and carefully with our rehabilitation staff, but during her course several rare happening occurred; she suffered from subdural hemorrhage due to hypocupremia and received an operation for the release of contracture of her hips. She died of acute cardio-respiratory failure at 8 years and 5 months of age. Her autopsy findings were characteristic of the damage to an immature brain during development; cactus formation of cerebellar cortex and periventricular leukomalacia.

Acute Disease↗
PubMed1992

[A case of frontal lobe epilepsy presenting with gelastic seizures].

We described a 9-year-old boy with frontal lobe epilepsy presenting with gelastic seizures. CT-scan showed mild widening of the left sylvian fissure. Abnormal findings in the left frontal operculum were detected by both MRI and SPECT. Attacks mainly consisted of gelastic seizures with comfortable feeling followed by screaming with fear. Administration of anticonvulsants resulted in reducing the frequency and severity of seizures. Finally the patient had brief laughter attacks only. In the present case, the clinical course suggests that the gelastic seizures does not occur by way of the spreading of epileptic discharges to the temporal or hypothalamic region; rather it might occur as a focal symptom of the frontal region.

Brain↗
PubMed1991

Primary structure of nuclease P1 from Penicillium citrinum.

The primary structure of nuclease P1, which cleaves both RNA and single-stranded DNA, from Penicillium citrinum was elucidated. The complete amino acid sequence consisting of 270 residues was determined by analysis of peptides obtained by digestion with Achromobacter protease I of the reduced and S-aminoethylated protein and by digestion with Staphylococcus aureus V8 protease of the reduced and S-carboxymethylated protein. Four half-cystine residues were assigned to Cys72-Cys217 and Cys80-Cys85. N-Glycosylated asparagine residues were identified at positions 92, 138, 184 and 197. Fast-atom-bombardment and laser-ionization MS were successfully used to confirm the determined amino acid sequences of peptides and to estimate the molecular mass of this glycoprotein having heterogenous sugar moieties, respectively. Comparison of the amino acid sequence of nuclease P1 with other nucleases revealed that the protein has a high degree of sequence identity (50%) with nuclease S1 from Aspergillus oryzae. The His-Phe-Xaa-Asp-Ala sequence (positions 60-64) is similar to the sequence (His-Phe-Asp-Ala) involving the active-site His119 of bovine pancreatic RNase A, and the Pro-Leu-His sequence (positions 124-126) is identical with the sequence involving the active-site His134 of porcine pancreatic DNase I.

Amino Acid Sequence↗
PubMed1991

Simple spike modulation of Purkinje cells in the cerebellar nodulus of the pigmented rabbit to optokinetic stimulation.

In immobilized pigmented rabbit anesthetized with N2O (70%) and halothane (2-4%), simple and complex spike responses of Purkinje cells in the cerebellar nodulus to large field optokinetic stimulation (OKS) was studied. About half of the cells showed significant simple spike modulation to OKS delivered to ipsilateral (25/57) or contralateral (18/31) eye. The preferred direction and the amplitude of modulation of simple spike responses did not necessarily correlate with those of complex spike responses, suggesting that the simple spike modulation is not secondary to complex spike modulation but due to modulation of mossy fiber activity to OKS.

Action Potentials↗
PubMed1991

Optokinetic response of simple spikes of Purkinje cells in the cerebellar flocculus and nodulus of the pigmented rabbit.

Under anesthesia with N2O (70%) and halothane (2-4%), Purkinje cell activities were extracellularly recorded in the flocculus and nodulus of immobilized pigmented rabbits. Large field (60 degrees x 60 degrees) optokinetic stimulation (OKS) was delivered to the central visual field of one eye with a constant velocity (0.1-4.0 degrees/s) at 0 degrees, 45 degrees, 90 degrees or 135 degrees to the horizontal plane of the eye. Most of the Purkinje cells in the flocculus and the nodulus showed significant simple spike modulations to OKS delivered to either eye. As a whole, the preferred directions of simple spike responses in the flocculus had the same orientation as those of complex spike responses. However, the preferred directions and amplitudes of modulation of simple spike responses did not necessarily correlate with those of complex spike responses in individual flocculus Purkinje cells. On the other hand, the preferred directions of simple and complex spike responses were not necessarily in the same orientation in the nodulus. The optimum velocity for simple spike responses was in the range 0.1-2.0 degrees/s for Purkinje cells in both the flocculus and the nodulus. The amplitude and time to peak of the simple spike responses of nodulus Purkinje cells were significantly smaller and longer, respectively, than those of flocculus Purkinje cells. In both the flocculus and the nodulus, Purkinje cells whose simple spikes preferred the horizontal orientation (H cells) and the vertical orientation (V cells) showed clustering. In particular, zonal organization was noted in the flocculus. H cells were localized in a dorso-ventral zone in the rostral one third of the flocculus, and V cells were in two distinct zones rostral and caudal to the H cell zone. The locations of H and V cells in the flocculus correspond to the H zone and V zones, respectively, determined on the basis of the preferred directions of complex spike responses to OKS. This indicates that the same subdivisions of the flocculus are supplied with optokinetic signals with the same orientation selectively through both mossy and climbing fibers, and suggest that such subdivisions of the flocculus are functional units which control horizontal and vertical components of optokinetic eye movements. The present results indicate that the flocculus and the nodulus are supplied with distinct optokinetic signals through mossy fibers and play different roles in controlling optokinetic eye movements.

Animals↗
PubMed1991

Optokinetic response of cells in the nucleus reticularis tegmenti pontis of the pigmented rabbit.

In immobilized pigmented rabbits anesthetized with N2O (70%) and halothane (2-4%), extracellular spikes were recorded from neurons in the nucleus reticularis tegmenti pontks (NRTP) and their responses to optokinetic stimulation (OKS) were examined. OKS was delivered using constant-velocity (0.1-4.0 degrees/s) movements of a random dot pattern (60 degrees x 60 degrees) at 0 degree, 45 degrees, 90 degrees or 135 degrees to the horizon. With OKS delivered to the contralateral eye (n = 43), the preferred directions of NRTP cells were forward (F, n = 10), backward (B, n = 7), downward (D, n = 5), and the remaining cells showed no response (N, n = 21). With OKS delivered to the ipsilateral eye (n = 43), the preferred directions were F (n = 8), B (n = 8), upward (U, n = 2), D (n = 1) and N (n = 24). The majority of cells which responded to OKS (17/22 for contralateral, and 16/19 for ipsilateral OKS) preferred the horizontal orientation. The optimum velocity ranged from 0.2 to 1 degree/s. The results suggest that the NRTP cells mainly transfer horizontal optikinetic signals to the flocculus and control horizontal optokinetic eye movements.

Animals↗
PubMed1991

Binocular interaction and signal components of optokinetic responses of climbing fiber afferents in the cerebellar flocculus and nodulus of the pigmented rabbit.

Under anesthesia with N2O (70%) and halothane (2-4%), Purkinje cells were extracellularly recorded in the flocculus and nodulus of immobilized pigmented rabbits, and complex spike responses to optokinetic stimulation (OKS) delivered simultaneously to both the ipsi- and contralateral eyes (binocular OKS) were compared with those to OKS monocularly delivered to the ipsi- or contralateral eye (monocular OKS). The complex spike responses to binocular OKS were an approximate summation of monocular responses to ipsi- and contralateral OKS. The complex spike modulation did not correlate with rhythmical slow and quick nystagmic discharges of the oculomotor nerve evoked by horizontal OKS. This suggests that complex spike responses originate largely from 'retinal slip' signals rather than from 'final motor command' signals represented in the discharges of the oculomotor nerve.

Afferent Pathways↗