After deproteinization with 70% aqueous ethanol and evaporation to dryness, a plasma sample was subjected to the formol reaction. Then Dns derivatization of imino acids was carried out for 20 min at 37 degrees C. An aliquot of the resulting solution was subjected to reversed-phase chromatography using continuous gradient elution with acetonitrile-50 mM acetate buffer (pH 4.0) as solvent system. This method is selective for imino acids. Hydroxyproline and proline levels could be determined using 30 microliter of plasma.

Chromatography, High Pressure Liquid↗

PubMed1985

Auditory brainstem response (ABR) to tone pips in hearing-impaired children.

The correspondence between ABR thresholds to tone pips and behavioral thresholds at 500, 1000 and 2000 Hz was studied in 13 normal and 55 hearing-impaired children, including 42 sensori-neural losses and 13 conductive losses. The children's ages ranged from 1 year 3 months to 8 years. Tone pips were provided with 2-cycle rise-fall times and 2-cycle plateaus. The correlations between the two measures were highly significant at 3 frequencies both in sensori-neural losses and conductive losses. In the subjects with sensori-neural losses, the ABR thresholds tended to be lower than the behavioral thresholds. Mean threshold differences between the ABR and behavioral audiometry at each frequency in sensori-neural losses were 1.6, 0.26 and 5.8 dB, respectively. On the other hand, in the subjects with conductive losses, the ABR thresholds were higher than the behavioral ones by 9.6, 7.8 and 7.5 dB at respective frequencies. Therefore, the hearing acuity in young children with sensori-neural losses can be predicted with accuracy from the ABR thresholds to tone-pips at 500, 1000 and 2000 Hz.

Audiometry↗

PubMed1985

Correlation between X-chromosome inactivation and cell differentiation in female preimplantation mouse embryos.

By means of a cytological method involving BrdU incorporation and acridine orange fluorescence staining in combination with embryo manipulation, we studied X-chromosome activity in female preimplantation mouse embryos with special reference to the correlation between X-chromosome inactivation and cell differentiation. There was no sign of asynchronous replication between the two X chromosomes from the one-cell to intermediate blastocyst stage. The allocyclic X chromosome, first detected in late blastocysts, was paternal in origin, mostly replicating early in the S phase and limited to the trophectoderm. Subsequent X-chromosome inactivation occurring in the primary endoderm was also characterized by the involvement of the paternal X and early replication. Both X chromosomes continued to replicate synchronously in the embryonic ectoderm or epiblast at this stage. It was evident that overt cell differentiation preceded the appearance of the asynchronously replicating X chromosome in the trophectoderm and primary endoderm. This finding seems to support the view that cell differentiation is an important correlate of X-chromosome inactivation.

Acridine Orange↗

PubMed1985

Serum concentration and effects of a single dose of enalapril maleate in patients with essential hypertension.

The antihypertensive effect of a non-sulfhydryl, long acting ACE (angiotensin converting enzyme) inhibitor, MK-421, was evaluated by administering a single dose of 10 mg to 13 patients with mild to moderate essential hypertension. The pharmacokinetic profile of MK-421 and its potent active metabolite, MK-422, was also assessed, together with the effect on the various components of the renin-angiotensin system. A single dose of MK-421 produced a significant fall in MBP from 2 to 24 hours post-drug. As could be expected, plasma ACE activity was suppressed up to 24 hours after MK-421. The half-life of MK-422, Cmax and [AUC]24(0) of MK-421 and MK-422 were measured. No significant change in plasma bradykinin or urinary excretion rate of kallikrein was observed, whereas a slight increase was observed in the urinary excretion rate of kinins after MK-421 in 8 patients. Significant correlations were observed between pretreatment PRA levels and the maximum fall in MBP.

Adult↗

PubMed1985

Effect of tone-burst frequency on fast and slow components of auditory brain-stem response.

By means of digital filtering, averaged auditory brain-stem responses (ABR) were divided into slow and fast components with frequency compositions of 50-300 Hz and 400-1 500 Hz, respectively, and the relation of the two components to stimulus frequency was investigated. Tone bursts with a rise-decay time of two periods of the chosen frequency with no plateau (2-0-2) and with a 4 ms rise-decay time with no plateau (8 ms duration) were used as acoustic stimuli. Tone-burst frequencies were 0.5, 1, 2, 4 and 8 kHz at an intensity level of 40 dB nHL. The amplitude ratio of wave V of the fast component to the slow component decreased with decreasing stimulus frequency, and it remained almost unchanged at each stimulus frequency regardless of the rise-decay time of the stimuli. From these results, it became clear that the frequently-mentioned audiometric difficulties for lower frequency stimuli in ABR testing are related mainly to the low amplitude of the fast component for the frequency range below 1.0 kHz. The slow component, with relatively large amplitude for the low-frequency stimuli, is regarded as the most useful index in the ABR for threshold estimation of hearing.

Acoustic Stimulation↗

PubMed1985