Preparation of the human skull for skull base anatomic study.

Human skulls are unsurpassed in the ability to provide three-dimensional instruction in osteology as well as understanding the sites of soft tissue insertion and the intricate course of neurovascular structures in the skull base. Recent geopolitical developments in Asia have led to extreme difficulty in obtaining human skull specimens. The purpose of this article is to present a method for the preparation of dried human skulls from fresh and frozen cadavers using commonly available chemicals. The technique, requiring about 8 weeks total time and basic equipment, consists of maceration accelerated by several enzymes followed by defatting, washing, and bleaching. The skulls produced are of excellent quality and durability with no preparation artifacts. An economical source of skulls has now been reestablished to facilitate learning of the intricate relationships of the skull base.

Immunocytochemistry of alcohol dehydrogenase in the rat central nervous system.

A sensitive immunocytochemical method for the localization of alcohol dehydrogenase (ADH) in the rat brain is described. The method employs rat liver ADH isolated and purified with Cap-Gapp affinity chromatography. Antiserum to rat liver ADH is generated in rabbits, and used in the peroxidase-antiperoxidase immunocytochemical method. The method is compatible with both light and electron microscopic methods of tissue preparation. In the present report we describe the identification of ADH in neurons of the mammillary bodies, periaqueductal gray, and the cerebral and cerebellar cortices of normal adult rats. In all brain tissues examined, the enzyme is limited to neuronal cytoplasm, and only to some neurons. The restriction of the enzyme to a limited percentage of neurons in the central nervous system may help to account for the difficulty in demonstrating the enzyme in whole brain homogenates, as the dilution of enzyme-bearing cytoplasm with a large volume of enzymatically inactive tissue would reduce the specific activity of the enzyme to near the limit of detectability. In the cerebellar cortex, the enzyme is found only in Purkinje cell cytoplasm. In the other regions examined, we are unable to identify by other criteria a specific neuronal class that consistently displays ADH reactivity. The reactive cells seem to be generally midrange in size and bipolar or multipolar in configuration. The presence of ADH in certain neurons leads us to speculate that intraneuronal ethanol metabolism may lead to focal accumulation of acetaldehyde. The intracellular presence of this toxin may in turn help to account for brain dysfunction in acute ethanol intoxication, and the neuropathology of chronic alcohol abuse.

Alcoholism.

After heart disease and cancer, alcoholism is America's third largest health problem; it affects 10 million people, costs $ 60 billion, and is implicated in 200 000 deaths annually. Alcohol is involved in 50% of deaths by motor vehicle and fire, 67% of murders, and 33% of suicides. It contributes to morbidity in certain malignancies and to many diseases of the endocrine, cardiovascular, hematopoietic, gastrointestinal, and nervous systems. The fetal alcohol syndrome occurs in a third of the infants born to women who drink more than 150 g of ethanol daily during pregnancy; another third of the infants become mentally retarded. The prevalence of alcoholism is lower in elderly than in middle-aged persons, but detection is difficult and vulnerability to harm is great in the elderly, due to both pharmacokinetic factors and increased tissue sensitivity. Alcohol and aging are additive in their harmful effects. Although modern medical treatment is helpful, alcoholics are frequently misdiagnosed and mismanaged by health professionals. Total abstinence from alcohol should be a primary goal of treatment.

Dendritic vacuolization in the central nervous system of rats after long-term voluntary consumption of ethanol.

Adult male rats were housed in a colony environment for six months, with ad lib access to anise-flavored 10% ethanol in water. Animals were then removed from the colony, and their consumption of alcohol during a period in isolated housing was measured. Individual rats were scored as high, moderate, and low consumers. Animals from each scoring category were killed for light and electron microscopic study of central nervous system tissue. High consumers frequently displayed varicose distortions of the dendritic profiles, with internal membranous vesicles. Such abnormalities were rarely found in dendrites of low-ethanol-consuming colony mates. The dendritic vacuoles often appeared empty and membrane-limited. Some vacuoles contained membranous inclusions. Dendrites which displayed electron-lucent cavities without membranous limits or contents were also found. Some invaginations of dendritic membranes were identified. The possible sequential relationship between these forms of dendritic alterations could not be determined. Some neuron cell bodies displayed vacuolar inclusions as well. Dendritic and somatic abnormalities were found in cerebral and cerebellar cortices, hippocampus, mammillary bodies, and the periaqueductal gray matter of the brain stem.

Blood-spinal cord barrier response to transection.

The integrity of the blood-spinal cord barrier (BSB) distal to a surgical transection was evaluated at the light and electron microscopic levels, using the tracers Evans blue albumin (EBA) and horseradish peroxidase (HRP). At the light microscopic level, the orange fluorescence of the EBA was detected as far as 0.45 mm distal to the transection. The tracer was not only diffusely distributed in the neuropil but also was apparently taken up by ventral horn neurons and glial cells. A feathery halo of EBA extending beyond their walls indicated that there had occurred some leakage of EBA from intrinsic vessels into the surrounding cord tissue. The microvasculature was evaluated at the ultrastructural level for evidence of changes in permeability to HRP. Pinocytosis and vesicular transport of the protein were apparent in some endothelial cells. In addition, there was limited evidence for leakage across tight junctions. After 1 day the barrier selectivity appeared to be restored and vesicular transport of HRP was not found. Endothelial pinocytosis, however, appeared enhanced for as long as 7 days following injury.

Morphometric analysis of effects of spinal cord transection.

After spinal cord transection in the rat, endothelial reactivity to horseradish peroxidase (HRP) was quantified at the ultrastructural level. The ratio of the area of labeled endothelial vesicles to area of endothelium (pinocytotic index) was established using morphometric techniques. From 3 h through 7 days the pinocytotic index was significantly elevated as far as 10 mm distal to the transection site. Correlating these findings with a previously established blood vessel classification model, the tracer uptake was identified as both a pinocytotic and vesicular transport mechanism. The latter was associated with an acute response lasting as long as 1 day after transection. Thereafter, the barrier appeared to reestablish its selectivity and only pinocytotic uptake of HRP was apparent.

The effect of total parenteral nutrition or elemental diet on pancreatic proteolytic activity and ultrastructure.

Previous reports regarding the effect of an elemental diet (ED) on pancreatic secretion have been conflicting. This study was designed to assess the effect of a high-nitrogen ED or total parenteral nutrition (TPN) on proteolytic activity in the pancreatic exocrine cell. Forty-eight dogs were divided into 12 groups of 4 each. Group I (control) was fed commercial dog food. Groups II, III, and IV received 1, 2, and 3 days, respectively, of 25% glucose with 4.25% amino acids. Groups V, VI, and VII received 1, 2, and 3 days, respectively, of 25% glucose with 2.75% amino acids. Groups VIII, IX, and X received 3 days of ED given orally, via gastrostomy or jejunostomy, respectively. Groups XI and XII received 1 day each of either 2.75% amino acids or 25% glucose. The pancreas of each dog was then resected and processed for electron microscopy, or minced and analyzed for tryptic activity expressed as micromoles of benzoyl arginine ethyl ester (BAEE) digested per milligram of pancreatic protein. There were no significant differences in ultrastructure or in the levels of pancreatic tryptic activity between the control and the 11 experimental groups. It appears that during the short period of our treatment with TPN as well as ED, the exocrine cell retains its normal content of proteolytic enzyme. Reports of others that pancreatic secretion volume decreases with TPN and ED, coupled with our findings of stable intracellular tryptic activity, indicate that the synthesis and release of proteolytic enzymes have actually been reduced by TPN and ED. Thus, TPN or ED should benefit the patient with pancreatitis by decreasing pancreatic secretion as well as pancreatic proteolytic enzyme synthesis.

Patterns of vascular sprouting in the postnatal development of the cerebral cortex of the rat.

Light microscopic histochemistry for alkaline phosphatase was employed in a study of the development of vascular sprouting, with respect to time and distribution, inthe rat cerebral cortex. Sprouts were counted in the full thickness of the cerebral cortex at each day from birth to 21 days of age. Several distinct bursts of sprouting activity were observed at specific times and levels of cortex. From birth to 4 days of age, sprouting was intense in the superficial third of the cortex. At 7 to 8 days, a burst of sprouting was found which was greatest in the middle third. Additional bursts of sprouting appeared at 10 and 14 days. Developing vessels with characteristics of arteries, capillaries, or sprouts were alkaline-phosphatase positive, while veins were not. It is concluded that alkaline phosphatase is a useful marker for identification of both mature and immature vasculature, as it reveals patent and nonpatent vessels, and the sprouts which are precursors of the mature vascular bed. New vessels developing in the cortex arise mainly from blind sprouts of capillaries, evidently in response to the metabolic demands imposed by the maturational process. At birth, the majority of intracortical vessels are capillaries. By 10 days of age, most perforating vessels from the surface have taken on arterial or venous characteristics. The findings are discussed in connection with morphological and biochemical differentiation and the pattern of vascularization in the mature cerebral cortex.

An ultrastructural study of vascular proliferation and vascular alkaline phosphatase activity in the developing cerebral cortex of the rat.

Alkaline phosphatase cytochemistry was employed to study the distribution of this enzyme in blood vessels during vascular differentiation and maturation during the postnatal development of the rat cerebral cortex. Enzyme reaction product was present in early vascular sprouts, and also throughout the subsequent maturation and differentiation of capillaries and arterial vessels. Cerebral capillaries appeared to be patent soon after the fusion of a sprout tip with another vessel; no evidence for delayed or synchronous opening was obtained. The distribution of alkaline phosphatase reaction product in vessel walls changed during vascular maturation. In vascular sprouts, reaction product was found mainly in the narrow lumen. As vessels became patent, reaction product appeared also on abluminal surfaces, at first chiefly in the narrow spaces between overlapping vascular cells. As vessels matured, reaction product became more generally distributed around the abluminal surface. In relatively mature capillaries and arterial vessels, it was restricted largely to endothelial cell surfaces and the spaces between smooth muscle cells. The significance of this distribution is unknown. Some possible explanations, including the possibility of artifact, are discussed. No alkaline phosphatase reaction product was found in differentiated veins.

Immunocytochemical localization of glycerol-3-phosphate dehydrogenase in rat oligodendrocytes.

In this study, two indirect immunoperoxidase staining procedures were used to investigate the cellular localization of rat brain glycerol-3-phospate dehydrogenase (EC 1.1.1.8;GPDH). At the light and electron microscopic level, we found that the use of monospecific rabbit antibodies to GPDH consistently resulted in the specific staining of only one glial cell population. GPDH-positive cells in perineuronal, interfascicular and perivascular positions were identified as oligodendrocytes by classical morphological criteria. The specificity of GPDH antigen-antibody reaction was determined by qualitative and quantitative immunochemical methods and by imunocytochemical controls for immunologic and methodologic sources of nonspecific reaction product. The illustrative data from this study serve to qualitatively define GPDH as a biochemical marker for oligodendrocytes in rat central nervous tissue. In view of the fact that the synthesis of rat brain GPDH is specifically regulated by glucocorticoids, the positive results obtained in this study further warrant the interpretation that rat oligodendrocytes are target cells for glucocorticoids.

Laryngocele--an updated review.

This communication reviews the clinical and pathological features of 121 cases of laryngocele reported in the English literature and the authors experience with 10 cases. A case of an infected laryngocele presenting with airway obstruction and one of an external laryngocele associated with laryngeal cancer are described in detail. An instance of bilateral congenitally long saccules is also presented, and the role of this anomaly in the pathogenesis of laryngoceles is discussed.

Experimental immunogenic proliferative retinopathy in monkeys.

When a small amount of bovine serum albumin (BSA) was injected into the posterior vitreous body of a sensitized monkey, an immunogenic response occurred in the major blood vessels of the optic disk. In nonsensitized monkeys, the same phenomenon appeared after repeated intravitreal injections of small amounts of BSA. Focal leaks of fluorescein from the optic disk vessels were demonstrated by fluorescein angiography. Correlative light and electron microscopy revealed infiltration of acute and chronic inflammatory cells from the vessels of the optic disk into the vitreous body. When larger amounts of BSA were injected in sensitized monkeys, in addition to optic nerve involvement, there were scattered retinal vascular hemorrhagic and exudative lesions throughout the posterior pole. Immunologic mechanisms can result in preferential optic disk involvement with formation of proliferative lesions during the healing phase of the immunogenic inflammation.

Experimental immunogenic rubeosis iridis.

We have developed a primate model of rubeosis iridis in monkeys systemically sensitized to crystalline beef insulin. After intravitreal insulin injection, the dose-related immunogenic inflammation includes cells, flare, fibrin, and blood in the anterior chamber. With more severe inflammation, posterior synechiae, iris bombé, and cataracts occur. Of particular importance, new blood vessels develop within the stroma and on the anterior surface of the iris. Following injection of small amounts of insulin, the anterior surface vessels may regress over time, and the iris regains its normal appearance and coloration. However, the new stromal vessels persist and are cuffed by inflammatory cells including plasma cells. After injection of large amounts of insulin, more extensive structural alterations develop as noted above in conjunction with persistent iris anterior surface and stromal neovascularization. The relationship of rubeosis iridis to clinical inflammatory syndromes and to previous laboratory studies is discussed. Stromal neovascularization was a consistent finding in this experimental model even when anterior surface vessels regressed. On the basis of these experimental data and a review of publications describing human pathology, we believe that a broadening of the classic definition of rubeosis iridis is waranted to include a recognition of the stromal component of the clinical and pathologic findings.

Structural alterations in the ciliary process and the blood-aqueous barrier of the monkey after systemic urea injections.

The structural alterations induced in the monkey ciliary epithelium by intravascular injection of urea solutions were studied with the light and electron microscopes. Arterial injection of urea resulted in destruction of the nonpigmented epithelium and the consequent breakdown of the blood-aqueous barrier. The intravenous injection did not significantly affect the structural integrity of the ciliary epithelium. The intercellular zonulae occludens were not altered and the intercellular pathway from blood to posterior chamber remained closed to horseradish peroxidase. Intercellular uptake in large cytoplasmic vacuoles appeared to account for some late transport to the basal end of the nonpigmented epithelium. There was no comparable transport of peroxidase in vesicles or vacuoles through the nonpigmented epithelium in animals not subjected to intravenous urea treatment. Compared to the arterial route, intravenous administration of urea does not appear to pose a serious threat to the integrity of the ciliary epithelium.

Rubeosis iridis generated by insulin hypersensitivity.

There are important similarities between human and experimental monkey rubeosis iridis. We believe that we have developed a useful primate model to study iris neovascularization and that the possible role of immunity to insulin in the pathogenesis of human diabetic rubeosis iridis warrants further detailed consideration.

Effect of prostaglandin on the blood aqueous barrier in the rabbit ciliary process.

Distinct structural changes occur in the rabbit ciliary epithelium following intravitreal injection of prostaglandin E-1 (PGE-1). Up to four hours after PGE-1 administration, alteration of the pigmented epithelium was characterized by dilated intercellular spaces and the disruption of many intercellular junctions. The nonpigmented epithelium demonstrates a spectrum of morphologic variation from only some thinning of cytoplasmic processes to area of severe distortion. In these regions, marked thinning of the nonpigmented cells occurs in association with an absence of apical tight junctions. This alteration of the nonpigmented epithelium and its tight junctions allows for the leakage of proteins into the posterior chamber which is consistent with the breakdown in the blood-aqueous barrier. The temporal sequence of these changes would suggest a differential susceptibility of the pigmented and nonpigmented layers with the pigmented layers being affected earliest and the nonpigmented epithelium altered subsequently. The recovery of this epithelial change was rapid and complete and demonstrated the transient effects of PG on the ciliary epithelium with recovery of the blood-aqueous function by 8 hours after injection.