Changes in prostatic cytosolic cyclic AMP (cAMP)-dependent and independent protein kinases associated with aging in ACI rats were determined. A decrease in prostatic weight and tissue protein content (but not DNA) with age was noted. The cytosolic cAMP-dependent protein kinase was present predominantly as the type II isozyme. Total content of this enzyme per prostate declined by 37% in 12-month-old rats but remained relatively stable thereafter. However, the activity ratio (+cAMP/-cAMP) increased with aging, indicating an elevation in the amount of the holoenzyme or a decrease in the amount of the free catalytic subunit. Concomitantly the specific activity (activity/unit protein in the cytosol) of this enzyme was found to be increased; this is most likely due to the loss of bulk proteins in the cytosol, and may indicate a slower loss of this enzyme protein in relation to other cytosolic proteins. By comparison, the cAMP-independent protein kinase demonstrated a marked and progressive decline in amount as well as in specific activity with aging, e.g. 80-90% decline at 12 months of age. The above changes in these enzymes did not appear to be due to low circulating androgen in the animals, since they were not reversed on administration of 3.0 mg of testosterone propionate per rat daily for four consecutive days. It is therefore suggested that the above-described changes in prostatic cytosolic protein kinases are primarily associated with cellular senescence in this organ.

Aging↗

PubMedDate not supplied

Cross-correlation of the frequency-following response.

Frequency-following responses (FFRs) to a low-frequency stimulus in 16 normal-hearing human subjects were cross-correlated with the stimulus in an attempt to yield more easily recognizable FFRs at lower intensity levels and increase threshold sensitivity. Cross-correlation of these responses with the stimulus did not improve threshold sensitivity and latencies obtained from the cross-correlated FFRs showed more variability and were uniformly shorter than those of standard FFR measurement.

Acoustic Stimulation↗

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Optimal ('Wiener') digital filtering of auditory evoked potentials: use of coherence estimates.

Auditory evoked potentials (AEPs) to 40 Hz clicks and amplitude-modulated 500 Hz tones in human subjects were digitally filtered using an optimal ('Wiener') filter uniquely determined for each AEP. Use of coherence functions to compute coefficients appropriate for filtering grand average AEPs or subsets such as split-half averages is described. Wiener-filtered AEPs correlated better than unfiltered AEPs with split-half replicates and with reference AEPs (obtained with long data collection periods). Visual detection thresholds were lower (more sensitive) for the Wiener-filtered AEPs, but not as low as objectively determined thresholds using coherence values.

Acoustic Stimulation↗

PubMedDate not supplied

Optimal smoothing of coherence estimates.

We have previously described the usefulness of the magnitude-squared coherence function in analysis of auditory evoked potentials (AEPs) (Ear Hear., 1989, 20: 2-13). For each frequency of interest, the coherence value can be compared to a 'critical value' to determine whether a response is present. Coherence functions must be smoothed across either multiple subaverages or adjacent frequencies (or both) to be reliable, but there are trade-offs: increasing the degree of smoothing increases computational time and (in the case of frequency smoothing) reduces spectral resolution. Using AEPs to clicks and amplitude-modulated tones we investigated the effects of variable degrees of smoothing on threshold estimates in 10 normal human subjects. Thresholds were found to be lower for coherence estimates than for visual detection and are also lower for longer data collection periods. However, there appears to be little if any advantage to segment smoothing beyond 8-16 subaverages. The optimal degree of frequency smoothing is more difficult to specify, depending on the spectrum of the AEP being analyzed (especially the rate of change of phase), and the spectral resolution of the analysis system.

Acoustic Stimulation↗

PubMedDate not supplied

Objective response detection in the frequency domain.

Several different and related measures have been proposed for objective response detection in the frequency domain. We compared magnitude-squared coherence (MSC) to phase coherence (PC) using simulations with specified signal-to-noise ratios (SNRs) and varying numbers of subaverages; the performance measure was area under a receiver operating characteristic (ROC) curve. MSC was superior to PC; test time required for equivalent performance is about 3 times greater for PC than for MSC. MSC performance for a given final SNR increased with the number of subaverages, but reached a plateau at 16 subaverages. Simulations of noise non-stationarity (high-amplitude noise in some subaverages compared to the others) led to decreased performance advantage for MSC over PC. However, weighted averaging restored this advantage. MSC is shown to be a simple algebraic transform of Victor and Mast's (1991) "circular T2" statistic and of two earlier statistics; all have identical statistical power.

Computer Simulation↗

PubMedDate not supplied

Use of molecular techniques to study microbial diversity in the skin: chronic wounds reevaluated.

The skin is colonized by an array of microorganisms which form its natural microflora. Disruption to the normal barrier function of the skin (due to trauma or disease) may result in invasion of the dermis by opportunistic bacteria. To date, these organisms, which may contribute to the chronicity of skin wounds, have been analyzed solely by culture methods. It is increasingly realized that standard culture methods of analysis do not accurately reflect the full diversity of complex microflora. This review discusses the limitations of traditional culture approaches and reviews recent advances in molecular microbiological techniques which facilitate a more comprehensive characterization of the microflora within clinical samples. The currently available technologies and techniques are described, as is their use in clinical practice and their potential for diagnostic screening. Chronic venous ulceration of the lower limbs is an important skin disorder in which the microflora invading the dermal tissues contribute to the observed delayed healing. Using chronic leg ulcers as a working example, we show how strict culture and molecular microbiological techniques may be employed, for the first time in combination, to definitively characterize the invading microbial community of the dermis.

Chronic Disease↗

PubMedDate not supplied

False-positive DAT caused by variables in sample procurement.

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Blood Donors↗

PubMedDate not supplied

Angiontensin-converting enzyme activity in dunning rat prostate tumor.

A dipeptidyl carboxypeptidase activity in the Dunning rat prostate tumor was characterized. This enzyme demonstrated the most prominent properties of angiotensin converting enzyme (ACE): that is, it was stimulated by NaCl and Co(2+) and was potently inhibited by captopril. The enzyme solubilized by Triton X-100 had a molecular mass of 110 kDa as determined by gel filtration chromatography. The specific activity of ACE did not change with castration, indicating that ACE activities are not controlled by androgen. The role of ACE in the prostate and its tumors is not understood, but the ability of this enzyme to hydrolyze a number of bioactive peptides suggests that it may function in controlling the molecular forms or activity of regulatory peptides.

Animals↗

PubMedDate not supplied

Reverse zymography studies of protease inhibitors in the secretions of different lobes of rat prostate.

The purpose of this study was to determine whether protease inhibitors were a constituent of secretions from the different lobes of the rat prostate. A reverse zymography method was used employing gelatin substrate-SDS-polyacrylamide gel electrophoresis to detect inhibitors of trypsin in secretions of the ventral, lateral, and dorsal prostate lobes of the Sprague-Dawley rat. Inhibitors of approximately 34 and 63 kDa were detected in ventral prostate secretion and of about 63 and 73 kDa were found in lateral lobe secretion. However, no inhibitor activities were detected in secretions of the dorsal lobe. The protease inhibitors of ventral prostate secretion were partially purified by preparatory isolectric focusing and SDS-polyacrylamide gel electrophoresis. The 34-kDa (pI 5.6-6.4) inhibitor had a higher activity against trypsin, whereas the 63-kDa (pI 6.4-7.0) inhibitor was more active against chymotrypsin. The rat prostate appears to have a lobe-specific distribution of secretory serine protease inhibitors.

Animals↗

PubMedDate not supplied

Hearing loss in graduates of a tertiary intensive care nursery.

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Brain Stem↗

PubMedDate not supplied

The auditory brain stem response reliably predicts hearing loss in graduates of a tertiary intensive care nursery.

Babies (N = 642) were tested for auditory disorder, using the auditory brain stem response (ABR), at the time of their discharge from a tertiary intensive care nursery (ICN). Of those with ABR threshold elevation in one or both ears (N = 97), 61% (N = 59) were retested some months later by a battery of audiological tests; 21 (N = 3.3% of the 642) suffered binaural peripheral loss and 11 (1.7%) now wear hearing aids. These new data, when combined with similar data previously reported from the same ICN, yield a sample of 1613 babies examined during a 5.8-year period from which these conclusions emerge: (1) About 16% of our ICN babies leave the hospital with reduced sensitivity in one or both ears; (2) the hearing deficiency is permanent for 8 to 10%; (3) the loss is sensorineural, bilateral, and so severe for about 4% that hearing aids will be required to optimize their language and psychosocial development. Use of the ABR procedure for neonatal hearing testing is the target of several criticisms: it is being applied too early in life; its predictions about permanent hearing loss are unacceptably inaccurate; or/and it is too costly. We discuss these and still other objections that have been raised.

Audiometry↗