Auditory ossicle abnormalities and hearing loss in the toothless (osteopetrotic) mutation in the rat and their improvement after treatment with colony-stimulating factor-1.

Osteopetrosis describes a group of skeletal metabolic diseases of heterogeneous etiology and varied severity that produces a generalized accumulation of skeletal mass, the result of reduced bone resorption. Inherited in a variety of species including humans, the most severe forms are lethal. Among common features are progressive blindness and deafness of controversial etiologies for which there are no universally effective treatments. We have studied the auditory responsiveness and auditory ossicle quantitative histomorphology and temporal bone vasculature in the toothless (tl) rat, a lethal osteopetrotic mutation with few osteoclasts, very low bone turnover, and limited angiogenesis in the axial skeleton. Compared with normal littermates, 3-week-old mutants showed significantly reduced auditory responsiveness, a hearing loss due to abnormalities in both form and tissue composition of the stapes, and little capillary sprouting in the vascular bed of the temporal bone. Treatment of mutants with colony-stimulating factor 1 (CSF-1), known to greatly reduce sclerosis in the axial skeleton, significantly improved hearing, stapedial form and tissue composition, and angiogenesis in the temporal bone. In normal rats, the stapes consisted of 89.3% bone, 9.1% mineralized cartilage, and 0.8% porosity. In osteopetrotic rats, the stapes consisted of 48.3% bone, 35.9% mineralized cartilage, and 15.9% porosity, while after CSF-1 treatment, the bone content increased to 55.2%, cartilage was decreased to 21.7%, and porosity increased to 23.0%, respectively. This is the first demonstration of an auditory abnormality in an osteopetrotic animal mutation and shows that the hearing loss in tl rats can be significantly improved following treatment with CSF-1.

Long-lasting depression of rabbit aortic prostacyclin formation by single-dose irradiation.

Male rabbits were exposed to a single irradiation dose of 1000-5000 rad when 12, 15, 16, and 17 months old and were killed when 18 months old (i.e., 1, 2, 3, and 6 months after irradiation). Even after this long interval after irradiation, abdominal aortic prostacyclin formation was significantly depressed, whereas the nonirradiated thoracic aortic segment exhibited no significant alteration in vascular PGI2 generation. The data show that the severe decrease in PGI2 synthesis was not caused by deendothelialization induced by irradiation alone. The data support the view that a deterioration in the prostaglandin system regulating hemostatic balance is an important determinant in the development of radiation-induced vasculopathy.

The efferent innervation of the avian cochlea.

The efferent auditory innervation of the budgerigar (Melopsittacus undulatus) was investigated by means of acetylcholinesterase staining. The course of the efferent fibres is described: the single terminal fibre regularly branches out to innervate several hair cells. Three types of efferent, axosomatic synapses could be distinguished: small outer hair cells bear large cup-like efferent synapses, intermediate hair cells with cone-shaped synapses, and tall inner hair cells with small, knob-like synapses. In the basal part of the cochlea the small hair cells with heavy efferent endings predominate, while in the apex only tall inner hair cells with small efferent terminals exist. There are more intermediate hair cells in the apical area than in the basal area.

Sphincters of canine hepatic sublobular veins respond to endothelin-1 and 3.

The dog has been used repeatedly as a model in liver transplantation research. The microcirculation and its regulatory mechanisms play a crucial role during ischemia and reperfusion. Little is known about the role of venous sphincters in regulating blood flow in the dog liver. Hence, we performed this study to elucidate their potential role in regulating local blood flow. In 14 dogs mean systemic (MSP) and mean portal venous pressure (MPP) were measured. Light and electron microscopy (scanning and transmission) of tissue sections and vascular corrosion casts were used to elucidate the microvascular morphology. Immunocytochemistry was applied to identify smooth muscle cells and the innervation of venous sphincters. Endothelins 1 and 3 were injected to find whether the hepatic venous sphincters are sensitive to these vasoactive agents. Tufts of smooth muscle cells were found in the sublobular veins (SLV; 100 to 250 microm in diameter), that reduced the luminal diameters of veins by 34%. Nerve endings were not observed close to these venous sphincters. The MSP and MPP were 75.3+/-2.4 mmHg and 8.9+/-0.95 mmHg, respectively. Treatment with 1.0 microg/kg of endothelin-1 (ET-1) significantly increased the MSP, the MPP and the percentage of focal venous sphincter contraction by 39% (105+/-4.7 mmHg), 43% (12.8+/-1.7 mmHg) and 57% (53.5+/-4.7), respectively (P <0.01). Treatment with ET-3 caused a significant (P <0.01) decrease in the MSP, the MPP and the percentage of sphincter contraction by 19% (61.0+/-2.2 mmHg), 39% (5.8+/-2.9 mmHg) and 38% (20.9%+/-3.15). Sinusoids did not contain sphincters. Hepatic arterioles and central veins were not affected by ET-treatment. The contraction of SLV sphincters correlated with increases in MPP (r=0.81, P <0.01) and was related to the MSP (r=0.67, P <0.01). These data show that the smooth muscle sphincters in SLV of the dog liver are involved in the local regulation of blood flow and that these sphincters are stimulated by non-neurogenic mechanisms. These sphincters contract in response to ET-1 and relax in response to ET-3. Since ET-1 is released during and/or causes inflammation, e.g., during ischemia and reperfusion, its antagonists might be of benefit during transplantation reperfusion of liver.

Irradiation depresses prostacyclin generation upon stimulation with the platelet-derived growth factor.

Experimental and clinical findings demonstrated rather severe arterial lesions occurring in irradiated arteries. It is suggested that a local haemostatic imbalance might be one causative factor. Liberation of PDGF causes smooth-muscle cell proliferation and PGI2 formation by the arterial wall cells, inhibiting in turn further release of PDGF from the alpha granules of the platelets. A decreased ability of irradiated vascular segments to generate PGI2 upon PDGF stimulation described here might cause haemostatic imbalance and subsequent radiation-induced lesions.

Prostaglandin synthesis of the trachea in rats and guinea pigs.

The synthesis of 5 prostaglandins in the trachea of rats and guinea pigs is studied by means of radio-thin-layer chromatography. The role of PGs in physiological and pathophysiological processes is discussed.

[A semiquantitative method of determining alkaline phosphatase activity in human arterial wall]. / Eine semiquantitative Methode zur Bestimmung der alkalischen Phosphataseaktivität in der menschlichen Arterienwand.

A new method of semi-quantification of the alkaline phosphatase enzyme activity in human vascular tissue is described. An index is derived from the number of alkaline positive cells and the different levels of intensity of the staining reaction. In the autopsy and surgical material of male and female subjects aged between 40 and 60 a, we evaluated the alkaline phosphatase enzyme reaction of normal and atherosclerotic arteries after various incubation intervals. Tissue samples were obtained from aorta, common carotid artery, renal artery, splenic and anterior tibial artery, and Sparks prosthetic graft.

Modifications of the paraspinous muscle flap: anatomy and clinical application.

Soft-tissue defects of the back, particularly involving the paravertebral tissues, are generally covered with myocutaneous, muscle, or fasciocutaneous flaps. The case of a 64-year-old man with a paravertebral malignant fibrous histiocytoma is reported. To ensure adequately radical margins, the ipsilateral trapezius and latissimus dorsi muscles as well as the costal periosteum and the spinous processes were resected between T9 and T12. The resulting defect was covered with a pedicled latissimus dorsi flap and an island flap of the paravertebral muscles. Prompted by this case, we studied the blood supply of the paravertebral muscles in 10 cadavers. The vasculature was visualized after flushing with colored latex and microsurgical dissection. Another 4 specimens were subjected to angiography and tomography. In the majority of cases (8 of 10), three perforators emerging from the intercostal arteries were identified. These were found to communicate in a longitudinal and vertical direction. Before piercing the fascia, they ramified in three layers matching the layers of the paravertebral muscles. Since the intercostal arteries were shown to communicate through anastomoses of adequate caliber, the paravertebral muscles appear to be useful candidates for proximally or distally pedicled transposition or island flaps.

The microvenous valvular anatomy of the human dorsal thoracic fascia.

The use of free scapular fasciocutaneous flaps for reconstruction of recalcitrant grade 6 venous stasis ulcers has shown excellent early success rates. Venous refilling times measured postoperatively over the flaps by photoplethysmography have noted improvements to normal levels. Preliminary anatomic studies have demonstrated valves in the circumflex scapular veins of flaps used in reconstruction. The purpose of this study was to investigate and document the number, morphology, size, and location of valves in the human dorsal thoracic fascia. Ten scapular flaps were obtained from unembalmed cadavers and injected with methyl methacrylate. Each flap cast was divided into four parts: proximal, right and left, and distal, right and left. We reduced the size of specimens (the largest being 24 x 11 mm) and studied them in a scanning electron microscope. We identified all valves, estimated the diameter of the corresponding vein, calculated the depth of the valvular sinus, and related it to the corresponding venous size. Light microscopy and transmission electron microscopy were used as assisting tools applied to glutaraldehyde-fixed specimens. Analysis of injected specimens showed that valves were most abundant in veins with a luminal diameter of 30 to 120 microns (59.3 percent of 905 valves). The depth of valves became larger with increasing venous diameter. The sizes of valve sinuses were not different for individual valves. Except for veins larger than 1000 microns in diameter, there was no significant difference between the number of valves in different parts of an individual flap, nor were there significant differences between the valve numbers in different flaps. Most valves were bicuspid; only in the vein category of 30 to 120 microns were unicuspid valves encountered. Valves sometimes were located in series in a short segment of a vein; occasionally, they were found at the merging site of two veins. Transmission electron microscopy showed that valve leaflets had collagen fibers that ascended toward the tip of the leaflet and occasionally were accompanied by elastic fibers. Myofibroblasts were regularly present in the valve leaflets. These data show that fasciocutaneous flaps from the scapular region have numerous valves (90 valves on average in each flap) in the venous microcirculation. The microvenous valves in the dorsal thoracic fascia appear to be structurally similar to valves in larger veins. These valves may play a role in the improved hemodynamics and promising clinical outcome of patients with chronic venous insufficiency who have undergone free scapular flap reconstruction.

The efferent innervation in the region of inner hair cells in the organ of Corti.

The efferent innervation of the inner hair cells in Corti's organ of the laboratory rat and of a bat was investigated with help of histochemical staining of the inner spiral bundle. The area of acetylcholinesterase-positive fibres in the inner spiral bundle regions was measured. The bulk of the efferent fibres lie in the middle part of the cochlea. Towards the apical and lower basal turns a distinct decrease in the number of fibres was observed.

Melanocytes in the modiolus of the guinea pig cochlea.

The cochleae of pigmented and albinotic guinea pigs aged 6-8 weeks were examined by electron microscopy for melanocytes in the modiolus. Two different types of melanocyte were observed: i) The first (Type A) was characterized by spherical, uniformly pigmented stage IV melanosomes. No signs of melanogenesis were seen in this perivascular pigment cell form, which is found mainly in the region of the cochlear plexus. ii) The second, very rarely observed type of melanocyte (Type B) was characterized by fusiform to oval melanosomes in various stages of maturation. Connective tissue cells containing fusiform to oval melanosomes enclosed in membrane-bound vacuoles were frequently found. These two types can be regarded as corresponding to uveal (Type A) and dermal (Type B) melanocytes. The connective tissue of the cochlear plexus seems to be derived from the leptomeninx.

Prostaglandin synthesis by the lateral cochlear wall under streptomycin influence.

The synthesis of 4 prostaglandins (PGs), PGD2, PGE2, PGF2 alpha and PGI2, detected as 6keto PGF1 alpha in the guinea pig lateral cochlear wall (LW) was investigated under streptomycin treatment. Animals underwent daily injections of the antibiotic at dosages of 20, 100 and 200 mg/kg body weight. Prostaglandins were detected 1, 5 and 10 days after drug administration using radioimmunoassay. Under aminoglycoside administration a general reduction of PG-synthesis was evident, which was highest for PGI2. Already after 5 days of treatment the PGI2-synthesis was decreased down to 50% under the lowest drug dosage. The highest antibiotic dosage induced an abrupt decline of PGI2 synthesis, down to 26%, in animals with the longest duration of treatment. The significant synthesis reduction of PGI2 was followed by PGE2. The reduction of PG-synthesis seems to be influenced rather by duration than dosage of drug administration. The decreased synthesis of PGs under streptomycin treatment is interpreted as an inhibition of cell membrane phospholipids, the phosphoinositides. This assumption becomes plausible since the phospholipids represent endogenous precursors of the PG-synthesis.

[Streptomycin-induced damage of the spiral ganglion]. / Zur Steptomycinschädigung des Ganglion spirale.

The neuronal density in the spiral ganglion was investigated in normal and in streptomycin-intoxicated guinea pigs. Streptomycin was administered in a dose of 250 mg/kg for 21 days. 6 weeks after the streptomycin exposure a histological examination revealed a decrease in ganglion cell density in the spiral ganglion, with maximum loss in the apical portion of the ganglion. As mechanisms of the ototoxic effect, a secondary degeneration of spiral ganglion cells after hair cell loss or a primary neurotoxic degeneration are discussed.

Fine structure of the tendon of the human stapedius muscle: comparison of normals and clinically otosclerotic patients.

The tendon of the human stapedius muscle was studied in normal post mortem material and in clinical otosclerotic patients, using light and electron microscopy. Cross section profiles of collagen fibrils were measured in various regions of the tendon and the amount of elastin was estimated. The normal stapedius tendon consisted of three concentrically arranged portions: A cylindrical central part, a tube-like mid-portion, and a cortical layer. The central part was made up of collagen fibrils with only a few elastic fibers, the mid-portion contained collagen fibrils together with significantly more elastic material, while the cortical layer, again, showed a smaller amount of elastic fibers. Mean diameters of collagen fibrils in the central part of the tendon were 65.12 +/- 11.89 nm, in the intermediate layer 41.00 +/- 9.63 nm, and in the cortical layer 70.28 +/- 19.58 nm. Stapedius tendons from clinically otosclerotic patients, though showing the same construction, were characterized by significantly altered collagen fibrillar diameters (Mann-Whitney U-test). In the central part, mean diameters were reduced to 61.05 +/- 14.70 nm, in the mid-portion increased to 50.90 +/- 10.08 nm, and in the cortical layer reduced to 61.09 +/- 8.49 nm. The changes of collagen cross section profiles estimated for the entire tendon were significant as well: 59.68 +/- 18.74 nm in controls versus 57.82 +/- 12.53 nm in otosclerotic patients. Elastin content in the mid-portion of control stapedius tendons increased with age (13% at 35 years of age to 35% at 70 years of age).(ABSTRACT TRUNCATED AT 250 WORDS)

[Cells of the vascular wall synthesize thromboxane]. / Gefässwandzellen synthetisieren Thromboxan.

Cultured endothelial and smooth muscle cells, as well as vascular tissue samples derived from human coronary arteries and minipig aorta produce thromboxane A2 in trace amounts. The identity of this substance was characterized using a specific thromboxane synthetase inhibitor. Thromboxane (TXB2) was measured by means of specific radioimmunoassay. The biological importance of this phenomenon is unclear.

[Radiation vasculopathy--caused by a change in vascular prostacyclin synthesis?]. / Strahlenvaskulopathie--bedingt durch Anderung der gefässeigenen Prostazyklinsynthese?

Earlier investigations revealed morphological damage of the vascular wall after radiotherapy. The present investigation was undertaken to determine whether vascular prostacyclin synthesis plays a causative role in the genesis of vasculopathy. Rabbits were exposed to a focal radiation dose of between 500 and 5000 rad over various time intervals. Vascular PGI2-synthesis increased significantly immediately after radiation, with a subsequent decrease over the following days to levels below the starting values. Each repeated radiation dose induced a significant increase in PGI2-synthesis again. These observations were paralleled by severe morphological alterations, mainly localized in endothelial cells and elastic material. The findings suggest that a deterioration in PGI2-synthesis plays a key role in the genesis of radiation-induced vasculopathy.

[Collateral circulation of the left colon: historic considerations and actual clinical significance]. / Die kollaterale Gefässversorgung des linken Hemikolons. Historische Beobachtungen und aktuelle klinische Bedeutung.

INTRODUCTION: The arterial communication between the superior and inferior mesenteric arteries is important in surgery of the colon and aorta. METHODS: The anastomosis between the median colic artery (ACM) and the superior colic artery (AMS) was studied on 52 cadavers (32 female, 20 male). The length of the artery was measured using a flexible scale, and its diameter was determined at three different locations (origin, middle, end). RESULTS: The median lengths of the arteries were: 6.8 cm (range 3.9-9.7) for ACM, 12.2 cm (range 7-17.4) for ACS, and 23 cm (range 13.6-34.2) for margin artery. The median diameters were: 3.4 mm (range 2.7-4.1) for ACM, 3.1 mm (range 2.1-4.1) for ACS, and 2.7 mm (range 2-3.4) for margin artery. In 9.6% of the cadavers ( n=5), additional anastomoses between the AMS and inferior mesenteric arteries were proven. In 90.4% ( n=47), only margin arteries were found. SUMMARY: The low incidence of an additional communication (Riolan's arch) and possible additional impairment of the blood supply should be taken into account during operation.