For the causal evaluation of occupational hearing damage it is important to identify definitely the noise source. Here we tested, whether recordings of distortion product otoacoustic emissions (DPOAEs) in awake guinea pigs can distinguish the effects of different industrial noises. Six groups of 12 animals each were investigated before and over four months after a single 2 h exposure to specific, played-back industrial noise as well as before and for 2 months after impulse noise exposure. We compared broadband noise (buzz saw, bottle washing machine), low frequency noise (drawing press), and mid-frequency noise (bottle filling machine). All animals had stable DPOAE levels before noise exposure. Frequency specific decreases in DPOAEs were found after exposure to the different noises. Broadband noise diminished mostly all frequencies tested, whereas low- or mid-frequency noise had a greater effect on DPOAE evoked by middle and higher frequencies, respectively. DPOAE evoked by middle and higher frequencies were obliterated after impulse noise. Morphological analysis of the cochleae confirmed these alterations. OHC loss was found in the middle turns of the cochleae corresponding to the diminution of DPOAE. We conclude that different kinds of industrial noise tend to produce typical changes in DPOAE levels.

Introduction: Arthroscopic methods in treatment of chondral defects aim to get smooth cartilage surfaces. Mechanical and thermal methods are used. Often the clinical results are poor or moderate. The treatment of chondral defects by using a hydro jet is an innovative measure. This study was aimed to evaluate the quality of the chondral surfaces after mechanical, thermal and hydro jet treatments in an in vitro scanning electron microscopy (SEM) study. Materials and methods: Femoral osteochondral pieces of the lateral condyle were obtained intraoperatively from patients undergoing total knee arthroplasty for primary knee OA. Partial-thickness cartilage degree II defects were smoothed by a mechanical shaver, bipolar radio frequency energy (RF) and hydro jet (84.1 KPa). SEM was carried out to evaluate the effects of the treatment. Results: Mechanical shaving produces a rough surface with groves and open lying collagen fibers. The surface, after bipolar cool ablation (coablation) was also uneven. The matrix was destroyed by massive vacuolization. Hydro jet treatment produces a relatively smooth surface without open lying collagen fibers. Conclusion: It is not possible to produce even surfaces by mechanical shaving or bipolar treatment. Hydro jet treatment allows a precise cutting which causes a relatively smooth chondral surface.

In long-term experiments in awake guinea pigs (n = 12), distortion product otoacoustic emissions (DPOAEs) at various frequencies were measured repeatedly over 6-8 months. About 9 weeks after the first measurement, the animals were exposed to industrial noise (car industry, maximal intensity about 110 dB SPL) for 2 h. The amplitudes of DPOAE were measured prior to noise exposure and 10 min, 70 min, 1 day and 2 days after the noise exposure and then once every week. Three to four months after noise exposure, the animals were killed, and the cochleae were prepared for scanning electron microscopy. The row of inner hair cells (IHCs) was complete in all animals, while the rows of outer hair cells (OHCs) showed a considerable hair cell loss in some of the animals without a correlation to the change in amplitudes of DPOAE. However, a closer relationship between the decline of amplitudes of DPOAE and the number of missing and changed OHCs (fused stereocilia bundles, missing tip links) could be established. The number of lost OHC does not reflect the decline in DPOAE in all cases. This discrepancy must be considered when the degree of hearing loss needs to be established from changed DPOAE.

Conflicting opinions in the recent literature indicate that the morphological organization and function of the anorectal continence organ has, up to now, not been clearly understood. But a clear imagination of the spatial arrangements of this compound muscle system is of clinical relevance for the pediatric surgeon performing reconstructive surgery. We analyzed 18-microm sections of the pelvic region of 4 human fetuses in order to describe the individual components of this muscle complex. A series of 630 Azan-stained sections was the base for the computer-assisted 3D reconstruction of the levator ani and the external sphincter complex in a male human fetus (14th week p.c.). In this context, special attention was paid to the intermediate muscle layer of the puborectalis which develops ventrally from the funnel-shaped levator ani and joins the tripartite ring system of the sphincter muscle dorsally. Our findings lead to a clear imagination of the spatial arrangement of this intermediate layer and characterize the anorectal muscle complex as an integrated ensemble in which the puborectalis holds a key position.

An unusual case of pulmonary atresia with an aberrant karyotype of 46,XX,t(6;8)(p21.2;q11.2) is reported. Fetal ultrasonic examination at the 20th week of gestation revealed a hypoplastic right ventricle and an intact interventricular septum. Authors summarize their postnatal findings in fetal heart and the large adjacent vessels with special reference to the pathogenesis of this rare congenital heart defect. The observation delineates right-ventricular outflow tract obstruction associated with an abnormal pulmonary blood supply. The anatomy of the systemic pulmonary collaterals was studied and correlated with multifocal disorders in the system of the pharyngeal arch arteries in the early embryonic development.

We report on findings in guinea pigs with objectively tested normal hearing ability. At the apical end of the Corti organ only in the inner row of hair cells the stereociliae are detectable by scanning electron microscopy. Here the row is interrupted several times. Near the helicotrema we find first the inner row of the outer hair cells, then the middle row and finally the outer row. At the beginning of the D-turn their arrangement is disordered. Normally, at the basal end of the D-turn all rows of inner and outer hair cells show their typical formation. This finding should be taken into consideration when making a cochleogram for proving of experimental noise damages.

Distortion product otoacoustic emissions (DPOAEs), a sensitive detector of outer hair cell (OHC) function, cochlear microphonics (CM), and hair cell loss have been monitored in 12 awake guinea pigs before and after 2 h exposure to specific, played-back industrial noise (105 dB SPL maximal intensity). All animals had stable DPOAE levels before noise exposure. In the first hours after noise exposure DPOAE levels were reduced significantly. In about 70% a partial recovery of the DPOAEs was found within 4 months after noise exposure. In 16% of the investigated ears no recovery of DPOAEs was observed. However, in a few ears increased DPOAEs were observed after noise exposure. Exposure to industrial noise caused both morphological changes in the middle turns of the cochlea and electrophysiological changes in the middle frequency range. A close correlation existed between reduced DPOAE levels, loss in CM potentials, and area of damaged or lost OHCs, but not with the numbers of damaged or lost OHCs in the cochlea. It can be concluded that continuous industrial noise causes a damage to OHCs which differs form the damage caused by impulse noise.

We report on findings in guinea pigs with objectively tested normal hearing ability. At the apical end of the Corti organ only in the inner row of hair cells the stereociliae are detectable by scanning electron microscopy. Here the row is interrupted several times. Near the helicotrema we find first the inner row of the outer hair cells, then the middle row and finally the outer row. At the beginning of the D-turn their arrangement is disordered. Normally, at the basal end of the D-turn all rows of inner and outer hair cells show their typical formation. This finding should be taken into consideration when making a cochleogram for proving of experimental noise damages.

A novel method is described for the separation on a single gradient of the major intracellular organelles of the secretory pathway, the Golgi, the smooth endoplasmic reticulum, and the rough endoplasmic reticulum. Total microsomes were prepared from rat liver by differential centrifugation and resuspended in 20% iodixanol. The microsomal suspension was then layered between a 30% iodixanol cushion and a layer of 15% iodixanol and centrifuged in a vertical rotor for 2 h. The microsomes distributed in four visible bands. The gradients were collected by upward displacement and were characterized (i) by determination of UDP galactose-galactosyltransferase (Golgi marker) NADPH-cytochrome c reductase (endoplasmic reticulum marker) and RNA (rough endoplasmic reticulum marker); (ii) by immunoblotting for TGN38 (trans-Golgi marker) and GS28 (cis-Golgi marker) and for protein disulfide isomerase (endoplasmic reticulum lumenal marker); (iii) by determination of the lipid composition; and (iv) by electron microscopy. The results suggest that the top band (density 1.045–1.090 g/ml), which contains 68% of the galactosyltransferase activity, consists of vesicles derived from the Golgi. The second broad band in the middle of the tube (density 1.130–1.160 g/ml), which contains 54% of the NADPH-cytochrome c reductase activity, consists mainly of vesicles derived from the smooth endoplasmic reticulum, overlapped at the top by a small band of Golgi-derived lamellae. The two bands at the bottom of the tube (density 1.130–1.160 and density 1.180–1.220 g/ml) appear to contain two subfractions of vesicles derived from the rough endoplasmic reticulum.

Granulated convoluted tubules are the specific ductal segment of the submandibular glands of mice and rats. These tubules are functionally integrated into hormonal circuits, produce regulatory peptides as well as epidermal and nerve growth factor. The experimental studies on adult male Wistar and Fischer 344 rats demonstrate acute cytotoxic lesions of the granulated tubules by means of a single dose of 2-acetylaminofluorene. After only a few administrations of the compound the intralobular duct tree is lined by an atrophic epithelium with loss of specific structures, the EGF immunoreactivity and the susceptibility to further cytolethal effects. The early selective damage of the granulated convoluted tubules indicates that the growth factor production and certain drug-metabolizing/drug-excreting capacities are situated within the same ductal segment. It is considered that other systemically administered compounds might also influence this growth factor-producing ductal segment, though less dramatically than 2-acetylaminofluorene.

Ciprofibrates (racemate and both enantiomers, Raccip, R- and Scip) were administered orally in doses of 1 and 10 mg/kg once daily over 28 days to male inbred Fischer 344 rats, age 90-110 days at the beginning of the experiment. Body mass gain was observed in all groups. The 1 mg groups showed almost no difference to the control group. The 10 mg groups exhibited less body mass gain, most pronounced in the Scip group. Liver masses were increased in a dose dependent manner up to more than 200%, only the 10 mg Scip group was not significantly different from the 1 mg group which exhibited an increase in liver weight to about 175%. Also the kidney weights increased to 130%, whereas thymus and spleen weights were decreased in the high dose groups. Liver microsomal cytochromes P450 (P450) concentrations were not altered in the 1 mg groups and distinctly lowered in the 10 mg groups. Ethoxyresorufin and ethoxycoumarin O-deethylations were lowered in all experimental groups in a dose dependent manner, after administration of the high doses down to 30% of the control levels or less. Pentoxyresorufin O-depentylation, however, was increased in all 1 mg groups. In the high dose groups it was not altered. Ethylmorphine N-demethylation was decreased after administration of the high doses by about 50%, but only Scip decreased this reaction also after administration of the low dose. NADPH/Fe2+-stimulaled microsomal luminol and lucigenin amplified chemiluminescence was increased, whereas hydrogen peroxide formation was depressed even by the low doses to 50% of the normal values, to about 25% by the high doses. Microsomal lipid peroxidation, however, was only slightly or not influenced. Glutathion concentrations (in the reduced and the oxidized form) were increased in a dose dependent manner by about 20 to 30%, the concentration of lipid peroxides was not significantly influenced. Thus, the effects of the enantiomers were not different and were similar to those of the racemate. In serum, cholesterol and triglycerides were only moderately lowered. Albumin concentrations were significantly enhanced in all groups, total proteins after 1 mg/kg Raccip only. Serum bilirubins were not altered, and among the indicator enzymes for liver damage only ALAT, alkaline phosphatase and the dehydrogenases were increased, in no case higher than twofold.Histologically distinct effects were seen after administration of both doses, more pronounced after 10 mg/kg, but with no differences between the enantiomers and Raccip: marked hypertrophy of the hepatocytes, reduced staining of the nuclei, strongly acidophilic granulated cytoplama, no basophilia of the cell bodies, loss of glycogen. These changes were most pronounced around the central veins. Hepatocyte apoptoses also were observed.By immunohistochemistry an increased staining was seen for all P450 isoforms tested (1A1, 2B1, 2E1, 3A2 and 4A1), predominantly perivenously and most pronounced after administration of the high doses without differences between Rcip, Scip or Raccip (preliminary results).By electron microscopy a moderate proliferation of per oxisomes after treatment with 1 mg/kg Cips with a ratio between mitochondria and peroxisomes of about 1:1 (controls: 10:1) was observed, and the peroxisomes were a more heterogeneous population. The relative portions of glycogen and both forms of the ER decreased. Treatment with 10 mg/kg Rcip, Scip or Raccip led to a strong increase in the number of peroxisomes, in some hepatocytes the ratio between mitochondria and peroxisomes was 1:3 with an increased heterogeneity among the peroxisomes evidenced by a broad range of electron densities. Most peroxisomes lacked a nucleoid.Thus, the biochemical effects differed only slighly and the morphological effects of the enantiomers were not different and were similar to those of the racemate.

Salivary glands of rodents are rarely affected with spontaneous and induced malignancies. This may be linked with low physiologic cell renewal and the infrequency of cytolethal actions by xenobiotics. The genotoxic 2-acetylaminofluorene, carcinogenic for other organs, causes acute damage in salivary ducts. In the submandibular glands the damage is limited to the granulated convoluted tubules. They produce and release regulatory peptides including epidermal growth factor and nerve growth factor. The partial chemical sialoadenectomy is repaired by sequential cell proliferation in the basal cell layer of interlobular ducts and in dilated intralobular ducts (day 4 and 6), in intermediate duct-like structures (day 6 and 8), and lastly in acini (day 8 and 12). This is associated with a transient loss of structural characteristics of striated ducts and acini (up to day 6) and of the immunoreactivity for S-100 protein (up to day 4). Actin immunoreactivity at the acinar base is increased from day 6 to 20. Analogous to the late postnatal differentiation of the granulated convoluted tubules, their structural characteristics and immunoreactivity for epidermal growth factor do not recover within 20 days. The acute lesion of the endocrine ductal segment is suggested to be causally involved with other systemic effects following treatment with 2-acetylaminofluorene. First, hypophagia with loss of body, liver and thymus weight may result from disturbed saliva production. Second, previous studies have shown a mitotic burst of the biliary epithelium and bloodborne lymphocyte-stimulating activities. Either effect could be brought about by regulatory peptides (see above), probably after elevated circulatory release from necrotic granulated convoluted tubules.