The central auditory conduction at term date and three months after birth. II. Auditory brainstem response

This communication describes the results of auditory brainstem responses (ABRs) obtained in 25 healthy mature newborns with a follow-up at 3 months of age. The combination of ipsi- and contralateral recordings, the intensity series and the comparison with the composite group averages are useful for the identification of the separate ABR components. Differences between the records after right or left ear stimulation were not observed. Comparing our data with those obtained by others, we conclude that the interpeak latency differences (IPLDs) offer a more consistent measure of ABR latency values than the peak latencies measured from stimulus onset. The simultaneously recorded ABRs ipsi- and contralateral to stimulation show both at term, and at 3 months, an equal central conduction time. The ABR II-V complex shows contralaterally a significant shift compared with the ipsilateral II-V complex. The significant latency changes observed between term and at 3 months are due mainly to the latency decrease in the II-III IPLD.

The central auditory conduction at term date and three months after birth. IV. Auditory cortical responses

Auditory cortical responses (ACRs) were recorded in 25 healthy mature newborns with a follow-up at 3 months. The waveform, latencies and amplitudes for the ACRs for this time period are studied. Topographic differences between the central and central-temporal derivations and changes between term and 3 months are found with respect to latencies and amplitudes for different peaks and troughs. The ACRs, obtained as a part of a protocol covering the entire auditory afference, offer consistent parameters, which can be used to study developmental neurophysiological properties of audition and which are potential diagnostic tools for the detection of deviant sensory or mental development.

The central auditory conduction at term date and three months after birth. III. Middle latency responses (MLRs)

Middle latency responses (MLRs) were obtained in 25 healthy newborns with a follow-up recording at 3 months in all but three. A four-channel recording provided topographic information. Linkage of the ear references reduced the myogenic contamination of the recordings. P0 and Na proved to be the most consistent components in the sinusoidal MLR wave sequence. Topographic differences suggest a generation of P0 and Na contralateral to stimulation. A significant latency decrease was found for P0 and na between term and 3 months. The most important latency and amplitude changes may occur before term date and immediately thereafter. The MLRs are the link between the auditory brainstem responses (ABRs) and the auditory cortical responses (ACRs), and it may be possible to use them for recordings in newborn infants. They provide information about the generation of specific components as well as regarding the auditory afference in the stimulus propagation between the brainstem and the cortical auditory areas.

Concanavalin A-peroxidase labeling in cervical exfoliative cytopathology. II. Routine assessment of labeling results

Concanavalin A-peroxidase (Con A-HRP) labeling of exfoliated cells of the uterine cervix have been shown to possess clinical significance in the detection of cancer. In the present study, a more simple method is used instead of the earlier applied complicated method. These two procedures for the assessment of the labeling results are compared. The first method is an objective machine-aided assessment procedure, consisting of a light microscope connected with a video system used in the sliced mode. The second is a more subjective method using human visual assessment with a light microscope only. The latter method would be suitable for routine use, if it shows similar Con A-HRP labeling results as obtained with the machine-aided procedure. In comparison with the machine-aided assessment procedure, the visual assessment procedure is less accurate. Moreover, the visual assessment is accompanied by intraobserver (between day) and interobserver variations. Although the discriminatory capacity in the detection of cancer patients is significantly lower for the human visual assessment procedure, this difference is small. It is of clinical relevance that in general a complete discrimination of healthy individuals and cancer patients is still possible. Therefore, visual assessment with a light microscope only, is preferred because of its simple equipment, which allows this procedure to be used as a routine method.

Urinary excretion of hydroxylysine and its glycosides in normal persons of different ages--influence of maturation

Basement membrane collagen is relatively rich in hydroxylysine and the glycosides of hydroxylysine, glucosylgalactosylhydroxylysine and galactosylhydroxylysine. In this paper a modified procedure for analysis of these substances in urine is described, using a purification-step with the cation-exchange resin Amberlite CG-120 type II and a modified program for amino acid analysis. Values are obtained from 75 healthy persons of different ages ranging from prematurity to adulthood. The influence of maturation is studied. Prematures and young children have a high and rather variable excretion of all components, whereas adults have low and similar excretion rates. Neither the ratio glucosylgalactosylhydroxylysine/galactosylhydroxylysine nor the percentage of glycosylated hydroxylysine can be shown to be age-dependent. These data are important for the study of collagen disorders, especially in childhood.

Use of the enzyme-linked immunosorbent assay for the early diagnosis of Mycoplasma pneumoniae infection

IgM and IgG antibodies to Mycoplasma pneumoniae were measured in 147 sera from four groups of patients by means of an indirect enzyme-linked immunosorbent assay (ELISA) and the results compared with those obtained by other methods. A good correlation was demonstrated between the complement fixation test and ELISA-IgM and to a lesser extent ELISA-IgG; for the metabolic inhibition test the reverse was the case. The indirect haemagglutination test appeared to detect mainly IgM antibodies. Low levels of IgM antibodies were detected by ELISA in 60 sera of children not suffering from pneumonia. However, if only high titres (greater than 800) were regarded as indicative of Mycoplasma pneumoniae infection, a presumptive diagnosis could have been made in 42 of 73 single acute phase sera from patients. Comparable results were obtained with IHA. The diagnostic level of IgM antibodies. was reached during the second week of the disease. It is concluded that examination of a single serum sample by either ELISA-IgM or IHA may assist in early diagnosis of Mycoplasma pneumoniae infection.

EEG spectra in children aged 8, 9 and 10 years. Reference values

In a group of normal children aged 8, 9 and 10 years power density spectra of a 100-second EEG period were made over four different brain regions. All children had to undergo medical and psychological examinations prior to this EEG and the criteria for normality were based on these examinations. Reference values of the power density distribution for children between 8 and 10.5 years are given.

The influence of the dentist upon dimensional change and creep of amalgam

A laboratory study showed insignificant effect on dimensional change was brought about by the operator's skill, packing technique employed, and alloy. However, creep was significantly affected by the operator's skill and the type of alloy.