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Biomedical subjects

M Ohki

Publications and source records attributed to M Ohki.

At least 145 records · Page 8Linked to original sources
PubMed1991

Construction and characterization of a NotI linking library of human chromosome 21.

Effective procedures have been developed for constructing NotI linking libraries starting from chromosome-specific genomic libraries. Fifteen different single copy and two rDNA NotI linking clones from human chromosome 21 were identified in two libraries. Their chromosomal origin was confirmed, and regional location established using hybrid cell panels. Hybridization experiments with these probes revealed pairs of genomic NotI fragments, each ranging in size from less than 0.05 to 4.0 Mb. Many fragments displayed cell type variation. The total size of the NotI fragments detected in a human fibroblast cell line (GM6167) and mouse hybrid cell containing chromosome 21 as its only human component (WAV17) were approximately 32 and 34 Mb, respectively. If these fragments were all non-overlapping, this would correspond to about 70% of the 50-Mb content estimated for the whole chromosome. The linking clones will be enormously useful in the subsequent construction of a NotI restriction map of this chromosome. Characterization of these clones indicates the presence of numerous additional sites for other enzymes that recognize sequences containing CpG. Thus most NotI linking clones appear to derive from CpG islands and probably identify the 5' end of genes.

Cell Line↗
PubMed1991

Image analysis of microsialograms of the mouse parotid gland using digital image processing.

We compared two digital-image feature-extraction methods for the analysis of microsialograms of the mouse parotid gland following either overfilling, experimentally induced acute sialoadenitis or irradiation. Microsialograms were digitized using a drum-scanning microdensitometer. The grey levels were then partitioned into four bands representing soft tissue, peripheral minor, middle-sized and major ducts, and run-length and histogram analysis of the digital images performed. Serial analysis of microsialograms during progressive filling showed that both methods depicted the structural characteristics of the ducts at each grey level. However, in the experimental groups, run-length analysis showed slight changes in the peripheral duct system more clearly. This method was therefore considered more effective than histogram analysis.

Animals↗
PubMed1991

Dimensions and resistances of the human nose: racial differences.

Dimensions of the external nose and nostrils and nasal airflow resistances were determined in healthy, young Caucasian, Oriental, and Negro adults. Statistically significant variation between racial groups was found in nasal width and the differential between dorsi-ventral and transverse nostril diameters. Corresponding differences were found also in nasal airflow resistances of combined and separate nasal cavities in both the untreated and decongested state. Caucasian noses were leptorrhine, Negro noses were platyrrhine, and Oriental noses were of intermediate dimension. Mean nasal resistances of untreated noses were 0.129 Pa/cm3/sec in Negroes (N = 17), 0.146 in Orientals (N = 20), and 0.184 in Caucasians (N = 24), and differences were more marked when noses were decongested (P less than 0.05 in all cases). Ratios between resistances of untreated and decongested noses showed no statistical differences between racial groups, suggesting a similarity in the mucovascular component of resistances.

Adolescent↗
PubMed1991

Quantitative analysis of ocular movements in Parkinson's disease.

In the present study, oculomotor abnormalities were investigated in 24 patients with idiopathic Parkinson's disease. Pursuit gain, slow and fast phase velocity of optokinetic nystagmus (OKN), saccade latency, amplitude and velocity, as well as vestibulo-ocular reflex (VOR) gain were quantitatively analyzed. Twenty-one out of 24 patients showed some abnormalities in their ocular movement. A reduction in pursuit gain, impaired OKN and a significantly increased saccade latency were observed in 11 patients. In 12 patients, hypometric saccade was seen, while a decrease in saccade velocity was observed in 10 patients. All patients registered normal values for VOR gain. Only one patient who had impaired smooth pursuit and decreased saccade velocity before treatment with a dopaminergic drug showed a remarkable improvement in these ocular abnormalities after treatment. These results suggest the possibility of dopaminergic control on these ocular movements.

Aged↗
PubMed1991

Visually induced eye movements in Wallenberg's syndrome.

Eighteen patients with Wallenberg's syndrome were investigated concerning visually induced eye movements. All results were analysed quantitatively using a computer. In 16 out of 18 patients, OKN slow-phase velocities were impaired, in the remaining 2 patients they were normal. Patients who showed impaired OKN were classified into two groups according to directional asymmetry of OKN impairment. In 7 out of the 16 patients, slow-phases toward the lesion side were predominantly impaired in contrast to the slow-phases toward the intact side (group A). In the remaining 9 patients, slow-phases toward the intact side were predominantly impaired (group B). The smooth pursuit showed the same asymmetry as the OKN slow-phase, except, in 4 patients who showed normal smooth pursuit. All patients showed reduced visual suppression of caloric nystagmus during the slow-phase of nystagmus toward the lesion side, except 3 patients who showed normal visual suppression in both directions. CT scan failed to detect either the brainstem or the cerebellar lesions in any cases, but MRI performed on the most recent cases demonstrated the infarctions clearly. These findings suggest that infarctions are localized in the medulla in the patients of group A, but extend to the cerebellum as well as to the medulla in patients of group B.

Adult↗
PubMed1991

Snoring, apnea and nasal resistance in men and women.

To examine if gender and airway resistance (nasal and pulmonary) influence the loudness and intensity of snoring, we prospectively studied 370 unselected patients referred to our sleep clinic because of heavy snoring and a possibility of sleep apnea. All patients had full nocturnal polysomnography, including measurements of snoring using a calibrated microphone-sound meter system, and determination of pulmonary (Raw) and nasal resistance (Rna). Snoring was quantified by reporting the number of snores per hour of sleep (snoring index--SI) and the maximum nocturnal sound intensity (dBmax). The patient population comprised 77 females and 293 males, ranging in age from 12 to 80 years. Based on the apnea/hypopnea index (AHI) we separated all patients into the apneic and non-apneic groups. There were 201 non-apneic snorers (AHI less than or equal to 10) and 160 apneic snorers (AHI greater than 10). There was no significant difference in snoring frequency, maximum nocturnal sound intensity, nasal and pulmonary resistance between men and women or between apneic and non-apneic snorers. Stepwise, forward, multiple linear regression analysis showed that body mass index and nasal resistance correlate significantly with the snoring index (R2 = 0.29, p less than 0.005), while age and body mass index correlate only weakly, but significantly, with the maximum nocturnal sound intensity. We conclude that (1) men snore similarly to women, and (2) obesity and nasal resistance are important determinants of the frequency of snoring. It follows that measures taken to reduce weight and decrease nasal resistance may be of benefit in reducing snoring.

Adolescent↗
PubMed1990

An F factor based cloning system for large DNA fragments.

An effective technique using an Escherichia coli plasmid system was developed to clone fragments of exogenous DNA of as large as 100 kilobase pairs. The characteristic features of this technique are the use of a low copy number (one to two) mini-F based plasmid vector and the introduction of artificial lambda cosR ends into the termini of DNA sources and then of the cosL ends into those of linearized vector molecules. This terminal modification greatly facilitated the formation of active large recombinant molecules, which was rarely achieved when the modification was omitted. The efficiency with which large recombinant clones can be generated is high enough to allow construction of a comprehensive library of higher organisms. All analyses of the plasmids recovered have revealed that the inserts were faithful replicas of the human DNAs used as sources.

Base Sequence↗
PubMed1990

Digital subtraction of radiograph in evaluating alveolar bone changes after initial periodontal therapy.

The purpose of this study was to determine the effect of initial periodontal therapy on crestal bone remineralization with the use of a digital subtraction method for quantitative analysis. Fifteen crestal sites randomly selected from five patients were examined at the initial visit, after completion of oral hygiene instruction, and 1, 3, and 6 months after scaling and root planing with standardized radiographs. The radiographs were digitized by means of a drum-scanning microdensitometer with a sampling aperture of 50 microns producing 256 gray levels and corrected for difference of contrast between image pairs. Results were as follows: (1) statistically significant changes were observed even 1 month after the therapy and (2) the extent of changes was quantitatively expressed and monotonically increased with time. These results indicate that subtraction radiography may be a reproducible and quantitative method for the evaluation of periodontal therapy.

Alveolar Process↗
PubMed1989

A complete deletion mutant of the Escherichia coli dnaKdnaJ operon.

Southern hydridization analyses of genomic DNAs from various dnaJ mutants of Escherichia coli showed that mutant K7052, which has well characterized dnaK706 and dnaJ705 double mutantions, is a deletion mutant. The deletion is about 8.0 kb long and encompasses the whole of the dnaKdnaJ operon.

Cloning, Molecular↗
PubMed1989

Tracking bacterial DNA replication forks in vivo by pulsed field gel electrophoresis.

The location of chromosomal DNA replication forks was identified in synchronously replicating E. coli cultures by pulse labeling DNA at specific times with 14C-thymidine and following incorporation of radionucleotide into genomic Not I restriction fragments. This technique could be used to characterize chromosomal DNA replication, to characterize mutations which affect this process, to identify the location of DNA replication origins and termini as well as aid in the construction of macrorestriction maps. Here, we further characterize the DNA replication mutations divE and dnaK and preliminary characterize the genomic organization of E. coli isolate 15.

Chromosome Mapping↗
PubMed1989

Anterior and posterior rhinomanometry.

Three rhinomanometric techniques for detection of transnasal pressures were compared by computer aided plethysmographic rhinomanometry. Mean unilateral resistances were measured in the decongested nose of an experienced subject by traditional anterior (sealed anterior catheter) and posterior (perorally by mouthpiece) rhinomanometry and also by a fine catheter inserted pernasally to the nasopharynx. No significant differences in magnitude (N = 25, p = 73, mean Rn = 0.345 Pa/cm3/sec) were found. Dimensions of an #8F catheter were adequate for conduction of transnasal pressures and the catheter placed along the floor of a decongested nasal cavity was found not to increase resistance to airflow significantly. Posterior pernasal catheter measurements were less variable than either traditional posterior (peroral) or anterior rhinomanometry. In 35 consecutive patients untreated by decongestant there were no significant differences in magnitude or variation between resistances of the combined nasal cavities immediately following insertion of the catheter and those obtained 5 minutes later (initial mean Rn = 1.66 + 0.49, 5 min mean Rn = 1.70 + 0.50) and in these naive subjects posterior rhinomanometric resistances averaged 9% greater than those in whom resistances were measured pernasally.

Humans↗
PubMed1988

Malignant transformation of nasal polyp. Case report.

Malignant transformation of nasal polyps is believed to be very rare. A 49-year-old man had suffered from nasal polyposis and visited the hospital complaining of nasal obstruction and a huge nasal polyp in the right nostril. Histologic findings showed squamous cell carcinoma with microinvasion on the surface of the polyp and no invasion of carcinoma in the stalk. Simultaneously, malignant transformation of a small polyp was found in the left nasal cavity. Clinical and histologic findings are discussed.

Carcinoma, Squamous Cell↗
PubMed1987

The Escherichia coli dnaJ mutation affects biosynthesis of specific proteins, including those of the lac operon.

Temperature-sensitive dnaJ mutants of Escherichia coli showed a thermosensitive defect in the synthesis of beta-galactosidase. Synthesis of the lac mRNA was greatly reduced at the restrictive temperature. The mutants were also conditionally defective in the synthesis of a subset of membrane proteins such as succinate dehydrogenase, whereas the synthesis of anthranilate synthetase, encoded by trpED, as well as that of most cellular proteins, was unaffected at the restrictive temperature. The defect was specific for the dnaJ mutants among several dna mutants which are known to be involved in the initiation of DNA synthesis: dnaK, dnaA, and dnaB mutants synthesized each of these proteins normally even at the restrictive temperature. At the restrictive temperature, growth of the dnaJ mutants was arrested at a specific stage of the cell cycle.

Anthranilate Synthase↗