Experimental autoimmune pinealitis in the rat: ultrastructure and quantitative immunocytochemical characterization of mononuclear infiltrate and MHC class II expression

Lewis rats immunized with Peptide M (an oligopeptide epitope of the S-antigen protein) developed experimental autoimmune uveoretinitis (EAU) and experimental autoimmune pinealitis (EAP). Temporal changes in mononuclear infiltrate to the pineal gland were quantitated by computer image analysis of sections immunostained with monoclonal antibodies to specific mononuclear populations. T helper/inducer cells (W3/25+) and monocyte/macrophages (OX-42+) were elevated during the early phases of inflammation (day 15) while cytotoxic/suppressor T cells (OX-8+) were elevated at days 15 and 21. Expression of MHC class II (OX-6) was markedly enhanced on pineal glia, but was not present on vascular endothelia during EAP. Ultrastructurally, many capillaries exhibited thickenings of the endothelia and basal lamina. EAP had little effect on the fine structure of pinealocytes and glia and there was little evidence of cellular destruction by day 21, in contrast to the extensive retinal destruction resulting from EAU. These findings suggest fundamental differences between EAU and EAP related to mechanisms of antigen processing/recognition in autoimmune diseases. Our study further indicates the importance of EAP as a model to investigate neuroendocrine-immune interactions.

The major calmodulin-binding protein in rabbit parietal cells is Ca2+/calmodulin-dependent protein kinase II

Parietal cell secretion can be stimulated by both histaminergic and cholinergic agonists. We have recently found that inhibition of calmodulin-dependent protein kinase II (CaMK II) activity can abolish cholinergic but not histaminergic stimulation of parietal cell secretion (Am. J. Physiol. 262:G118-122). We have investigated the presence of calmodulin-binding proteins and CaMK II in isolated rabbit parietal cells. Calmodulin-binding proteins with apparent molecular masses of 50, 60, 85, 100, and 240 kDa were observed. The major calmodulin-binding species was a 50 kDa band which was enriched in 50,000 g. microsomal membranes. The 50 kDa calmodulin binding comigrated with immunoreactivity for CaMK II. Partial purification of the microsomal CaMK II demonstrated a 250 kDa oligomer. The results demonstrate that CaMK II is the major calmodulin-binding protein in parietal cells and is associated primarily with light microsomal membranes.

Pinealocyte synaptic ribbons and neuroendocrine function

A comparative study of pinealocyte synaptic ribbons (SR) revealed two predominant populations exhibiting either a rod/ribbon shape (SRr) or a spherical/punctate shape (SRsp). Species-specific differences were found in the abundance of SR, the ratio of SRr/SRsp, and the occurrence of SR in ribbon fields. The close topographical relationship of SR to the plasma membrane and the numerical changes that occurred with changes in metabolism of the pinealocytes suggest that SR have important vesicle-mediated interactions with the cell membrane. Experiments designed to clarify the relationship between SR and pineal neuroendocrine function revealed a positive correlation between SR numbers and indole intermediates during pineal development in the rat, and increased SR frequency after denervation of the rat pineal gland or administration of the beta-adrenergic agonist, isoproterenol. These data are consistent with the hypothesis that SR function is linked to receptor mechanisms regulating indoleamine production in the pineal gland.

An inhibitor of Ca2+/calmodulin-dependent protein kinase II, KN-62, inhibits cholinergic-stimulated parietal cell secretion

Cholinergic stimulation of parietal cell secretion is mediated by an increase in intracellular calcium. KN-62, a selective inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMK II), has recently been synthesized (Tokomitsu et al. J. Biol. Chem. 265: 4315-4320, 1990). To define the role of CaMK II in parietal cell secretion, we determined the effects of KN-62 on secretagogue-stimulated acid secretion in isolated rabbit parietal cells. Pretreatment of parietal cells with KN-62 resulted in the inhibition of carbachol-stimulated [14C]aminopyrine uptake over a concentration range of 3 to 60 microM (IC50 of 20 microM). KN-62 (60 microM) reduced carbachol-stimulated aminopyrine uptake to unstimulated levels. KN-62 did not alter carbachol-stimulated increases in cytoplasmic free Ca2+ concentration. High concentrations of KN-62 (60 microM) elicited a small decrease in aminopyrine uptake stimulated by forskolin, but did not significantly inhibit histamine stimulation. A potent CaMK II activity was identified in total membrane from parietal cells. These results suggest that CaMK II may mediate cholinergic-stimulated parietal cell secretion.

Cardiac manifestations of Weber-Christian disease: report and review of the literature

A patient with chronic systemic Weber-Christian disease who was treated with hydroxychloroquine developed cardiac dilatation with congestive heart failure. Endomyocardial biopsy demonstrated myocyte degeneration and interstitial fibrosis, but no typical features of chloroquine induced cardiomyopathy. Clinical symptoms of congestive heart failure also were recognized in 7 of the 11 reported autopsy cases of Weber-Christian disease having cardiac involvement. This involvement can affect the pericardium and the myocardium.

Pineal gland transplants into the cerebral hemisphere of newborn rats: a study of the blood brain barrier and innervation

Pineal glands from neonatal (0-1 day) Long-Evans black-hooded rats were transplanted into the cerebral hemispheres of litter mates for periods of 1 to 5.5 months. Grafts exhibited differentiated pinealocytes that were intensely immunoreactive for serotonin. Transplant vasculature was permeable to endogenous IgG, comprised fenestrated endothelia with wide pericapillary spaces typical of in situ glands, and had a volume density intermediate to that of surrounding cortex and in situ pineals. Along the periphery, transplant capillaries tended to have continuous endothelia similar to those of host cortex. This peripheral zone was impermeable to endogenous IgG and appeared to increase in size in older grafts. The presence of noradrenergic-like fibers within the perivascular compartment suggested that transplants were innervated by peripheral sympathetic neurons from the superior cervical ganglia. In animals which had been superior cervical ganglionectomized, noradrenergic-like fibers were absent or degenerating. Neural regulation of transplant metabolic activity was suggested by the increased frequency of pinealocyte synaptic ribbons in denervated grafts. These findings are consistent with the hypothesis that factors from both graft and host influence vasculature physiology and differentiation in neural transplants. Furthermore, grafts appeared to receive appropriate neural input from the peripheral sympathetic system.

Circadian analysis of mononuclear cells in the rat following pinealectomy and superior cervical ganglionectomy

The role of the pineal gland and adrenocorticosteroids in circadian rhythmicity of immune function was investigated in Sprague-Dawley rats that either had been pinealectomized (PX) or had undergone superior cervical ganglionectomy (SCGX), which functionally denervates the pineal. For both experiments, conducted between August and October, rats were entrained to a 10-h light:14-h dark cycle and fed ad libitum. The circadian rhythm in monocytes (ANOVA, p less than .01 for Control + Sham + PX samples) tended to parallel that of plasma corticosteroid levels (ANOVA, p less than .01) with the peak during early dark and the nadir at early light. In comparison, suppressor/cytotoxic T cells and B cells tended to be more frequent during early light with minimum levels during early dark (ANOVA, p less than .05 and .01, respectively, for Control + Sham + PX samples). Natural killer (NK) activity in control animals varied significantly (ANOVA, p less than .05) over the light:dark cycle with peak activity during early dark in the SCGX experiment, but was only slightly elevated during late dark in the PX experiment. PX animals exhibited increased frequency of NK cells, but only in samples collected during the day (t test, p less than .05). This effect was not observed in sham-operated PX controls and in SCGX animals. Neither PX nor SCGX had a significant (ANOVA) effect on plasma corticosterone levels. These observations in the rat are consistent with findings in mice and humans that corticosteroids play an important general role in circadian rhythmicity of immune functions. In contrast, the present study suggests that pineal gland influence of immune function(s) is more specific and that pineal gland interaction with NK cells has a circadian component.

A circannual cycle in pinealocyte synaptic ribbons in the hibernating and seasonally reproductive 13-lined ground squirrel (Spermophilus tridecemlineatus)

Pinealocyte synaptic ribbons (SR) in the 13-lined ground squirrel were quantified at monthly intervals over a one-year period spanning the hibernating and reproductive cycles of these animals. SR numbers were high (70-90/20,000 microns2) during periods of activity and reproductive quiescence (May-October). With the onset of hibernation (November-December) there was a rapid 6 to 7-fold reduction in SR frequency. During arousal (January-February) and sexual maturation (March-April) there was a gradual increase in SR frequency. The winter decline in SR frequency is consistent with the decline in pineal melatonin during hibernation and supports the hypothesis that pinealocyte SR play an important role in the neurotransduction of melatonin biosynthesis.

Ultrastructure and organization of circumventricular organs and endolymphatic tubules in the treefrog, Hyla versicolor

The morphology and anatomical relationship of the paraphysis, anterior choroid plexus, and endolymphatic tubules of Hyla versicolor suggest that these structures may act as a functional unit to regulate composition of the cerebrospinal fluid (CSF). Ependymal cells of both the paraphysis and the choroid plexus exhibit ultrastructural features (an extensive microvillar border, large intercellular spaces containing an amorphous material, and apically located mitochondria) which indicate active exchange between the blood and CSF. Mast cells (which may play a role in regulating vascular permeability) also occur on the brush border. The tubules of the endolymphatic sacs were found to lie in close relation with the dorsal portion of the paraphysis. The endolymphatic organ is known to play a role in systemic buffering during respiratory acidosis and may influence Na/K fluxes via calcium release. The association of the paraphysis with the endolymphatic tubules may therefore represent an important mechanism for ion regulation in the CSF of amphibians. The ultrastructure of the pineal organ agrees with descriptions for other species. No pineal stalk was present. Photoreceptor inner and outer segments project into a central lumen continuous with the third ventricle. Outer segments show signs of disorganization. Photoreceptor/neural dendrite contacts involve synaptic ribbons and conventional synapses.

Day-night differences in the vesicle populations of nerve terminals in the rat and chick pineal gland

Day-night differences in the ultrastructure of pineal neuronal elements were quantitated in the rat and the chick--two species that exhibit important differences in adrenergic control of melatonin synthesis. Area densities of small clear vesicles (40-60 nm) and small dense-cored vesicles (40-60 nm) in nerve terminals were significantly reduced during the night in the rat. In the chick, there were no day-night differences in the frequency of clear vesicles, but the number of small dense-cored vesicles tended to be greater at night. There was no effect of day-night sampling on area densities of large dense-cored vesicles (80-120 nm) in either species. These findings are consistent with biochemical evidence for day-night species differences in the adrenergic control of pineal function.

Delayed redistribution in thallium 201 SPECT myocardial perfusion studies

Stress 201Tl myocardial perfusion studies are useful in differentiating viable, reversibly ischemic from infarcted myocardium. A perfusion defect that shows redistribution 2 to 4 h after 201Tl injection is diagnostic of ischemia, while a fixed defect suggests infarction. However, occasional patients with a fixed defect at 4 h have redistribution at 24 h. This study evaluates the frequency and significance of this delayed redistribution with SPECT 201Tl. Patients with either no or incomplete redistribution at 4 h had repeat imaging 18 to 48 h later. Delayed redistribution was seen in 8/26 (31 percent). Four had incomplete and four had no redistribution at 4 h. Delayed redistribution with SPECT 201Tl is more common than generally appreciated, and we recommend delayed images in patients with fixed perfusion defects or incomplete redistribution at 4-h imaging, particularly in patients with previous infarctions for whom a revascularization procedure is being considered.

Effects of isoproterenol on synaptic ribbons in pinealocytes of the rat and C57BL/6J mouse

Synaptic ribbons (SR) in melatonin-deficient pinealocytes of the C57BL/6J mouse were quantitatively compared to SR in pinealocytes of the rat after beta-adrenergic receptor activation by isoproterenol. Two populations of SR comprising synaptic spherules (SRsp) and synaptic rods (SRr) were described in both the mouse and the rat, but species differences existed in the ratio of SRr to SRsp. Isoproterenol caused a significant increase in frequency of SR of the rat but had little or no effect on SR populations in the mouse. It is unlikely that beta-adrenergic receptors are absent on mouse pinealocytes or were not activated since isoproterenol elevated plasma renin concentrations indicating activation of beta-adrenergic receptors. Furthermore the pineal of both species receives heavy sympathetic input. These findings indicate that the role and regulation of pinealocyte SR are complex and are functionally linked to beta-adrenergic receptors as well as other mechanisms related to the production of melatonin.

Day-night variability in acid phosphatase activity of pineal gland macrophages

Acid phosphatase (ACP) activity was investigated in the photoreceptive pineal gland of the goldfish by both light and electron microscopy. Intraluminal macrophages exhibited the greatest ACP reactivity that was generally confined to lysosomal bodies containing membranous debris. Quantitative light microscopic evaluation revealed significantly higher ACP reactivity in animals collected at mid-light compared to those collected at mid-dark suggesting that functional activities of macrophages in this photoneuroendocrine organ are cyclical over the 24-h photoperiod. Day-night differences in macrophage ACP activity may reflect rhythmic renewal and shedding of photoreceptor outer segment membranes.

Electrophysiology and ultrastructure of eustachian ridge from cat right atrium: a comparison with SA node

Intracellular microelectrode and electron microscopic techniques were used to investigate and correlate the electrophysiology of subsidiary pacemaker activity with the presence of cells having ultrastructural characteristics of pacemaker cells i.e. P cells, in Eustachian ridge tissue isolated from cat right atrium. In addition, the electrophysiological characteristics of subsidiary pacemaker activity and the ultrastructural characteristics of P cells in Eustachian ridge were compared to those of SA node obtained from the same hearts. Action potential recordings and morphological analysis were restricted to the endocardial site of earliest activation. Electrophysiological recordings revealed that spontaneously active Eustachian ridge tissues generate slow response action potentials with pacemaker characteristics similar, although not identical, to those of SA node. These included a relatively steep diastolic slope, low maximum diastolic potential (-70 mV), rate of rise (5.5 V/s), take-off potential (-52.5 mV), a relatively large overshoot potential (+7.7 mV) and a spontaneous cycle length (948 ms) about twice as long as SA node (434 ms). Morphological analysis revealed cells with ultrastructural characteristics of P cells, that were restricted to the endocardial site of earliest pacemaker activation. Morphological measurements indicate that Eustachian ridge P cells are not significantly different from P cells in SA node of the same hearts. However, Eustachian ridge P cells exhibit a unique apposition of subsarcolemmal cisternae between cells not seen in SA node. We conclude that pacemaker cells within the Eustachian ridge generate stable, spontaneous activity via slow response pacemaker action potentials. Cells responsible for this subsidiary pacemaker activity are most likely P cell types that are similar, although not identical, to P cells in SA node.

Pinealocyte dense-cored vesicles and synaptic ribbons: a correlative ultrastructural-biochemical investigation in rats and mice

Dense-cored vesicles (DCV) and synaptic ribbons (SR) were quantified in the pineal gland of the rat (Sprague-Dawley) and mouse (Sasco/ICR strain), and day/night differences in frequency of these organelles correlated with levels of indoles determined by high performance liquid chromatography (HPLC). There were significant day/night differences in levels of serotonin (5HT), 5-hydroxyindole acetic acid (5HIAA), N-acetyl-5HT, and melatonin in the rat gland. Melatonin and N-acetyl-5HT were not detectable in the mouse gland sampled every 4 h over the light:dark cycle. The concentrations of 5HT and 5HIAA (ng/microgram protein) were similar in light-adapted rats and mice, but these indoles did not exhibit a circadian rhythm in the mouse gland. Correlative ultrastructural/biochemical results suggest that DCV do not contain physiologically important stores of 5HT since 1) the mouse gland contains the same number of DCV as the rat during the daytime, but only one-tenth the levels of 5HT, 2) day/night 5HT levels do not vary in the mouse gland, but there is a significant nocturnal decline in DCV numbers, and 3) 5HT levels in the rat gland decline at night when DCV numbers increase. Numbers of SR were significantly elevated at night in the rat and mouse, and the frequency of this organelle was similar in both species. However, ribbon-type SR predominated in rat pinealocytes, whereas SR in the mouse were almost exclusively spherical in shape. Day/night differences in SR numbers in the mouse gland suggest that cellular mechanisms regulating the frequency of this organelle do not involve factors related to indole metabolism. Because of the lack of photoperiodic effects on indole metabolism in the mouse pineal gland, this species is a potentially important model to study the functional relationship of pinealocyte organelles to cyclical changes in pineal products other than indoles (e.g., peptide/protein factors).

The assessment of contractile reserve after thrombolytic therapy for acute myocardial infarction

"Stunned" myocardium prevents the assessment of myocardial salvage after streptokinase. In order to unmask "stunning," we sought to evaluate left ventricular inotropic contractile reserve of patients after streptokinase. Radionuclide ventriculograms were obtained in 75 consecutive patients 2 weeks after myocardial infarction, at rest and during intravenous isoproterenol infusion. Resting and isoproterenol-stressed ejection fractions were compared in the patent and closed-infarct vessel groups. Although there was no difference in the resting ejection fractions between the patent group (0.48 +/- 0.02) and the closed group (0.48 +/- 0.02), isoproterenol increased the ejection fractions in the patent group (increase 0.14 +/- 0.01) significantly more than in the closed group (increase 0.06 +/- 0.01) (p less than 0.0001). Thus, despite identical resting ventricular function, the greater inotropic contractile reserve in the patent infarct vessel group suggests that restoration of blood flow in acute myocardial infarction salvages myocardium.

Temperature dependence of protein transport across lymphatic endothelium in vitro

The purpose of the work was to develop an in vitro model for the study of lymphatic endothelium and to determine, using this model, whether or not a cytoplasmic process may be involved in transendothelial transport. Segments of canine renal hilar lymphatics were dissected clean, cannulated at both ends, and transferred to a perfusion chamber for measurement of transendothelial protein transport and for ultrastructural tracer studies. The segments were subsequently processed for light and electron microscopy. By both structural and functional criteria the lymphatics were judged to have retained their integrity. At 37 degrees C, 36 lymphatics showed a mean rate of protein transport of 3.51 +/- 0.45 (SEM) micrograms/min per cm2 of lymphatic endothelium. The rate was influenced by the temperature of the system, being significantly reduced by 49% +/- 4.8, 31% +/- 5.3, and 29% +/- 3.9 when the temperature was lowered to 4 degrees, 24 degrees, and 30 degrees C, respectively. When the temperature was raised to 40 degrees C, the rate was significantly increased by 48% +/- 12.2. The vesicular system and the intercellular regions in vessels with increased or reduced rates of transport were analyzed quantitatively to ascertain whether the rate changes could be correlated with ultrastructurally demonstrable changes in either of these postulated pathways. No significant changes in junctional or vesicular parameters were found between the control lymphatics and those perfused at 24 degrees, 30 degrees, and 40 degrees C. At 4 degrees C, the temperature at which the rate of protein transport was maximally reduced, vesicular size decreased, and the number of free cytoplasmic vesicles increased, whereas the number associated with the abluminal and luminal surfaces decreased. We concluded that isolated perfused lymphatic segments transport protein at a relatively constant rate under control conditions, and that this transendothelial transport comprises both temperature-dependent and temperature-independent mechanisms. The findings were considered in terms of the different theories of lymph formation and were interpreted as providing support for the vesicular theory.

Capacity of deoxycytidine to selectively antagonize cytotoxicity of 5-halogenated analogs of deoxycytidine without loss of antiherpetic activity

Enzyme kinetic studies from this laboratory (M. Dobersen and S. Greer, Biochemistry 17:920-928, 1978) suggested that deoxycytidine could antagonize the toxicity of 5-halogenated analogs of deoxycytidine without interfering with their antiviral activity. Antagonism by deoxycytidine of the toxicity of 5-chlorodeoxycytidine without impairing its anti-herpes simplex virus type 2 activity is demonstrated in the present studies. Tetrahydrouridine, an inhibitor of cytidine deaminase, was utilized. The high Km for deoxycytidine (0.6 mM) with respect to the herpes pyrimidine nucleoside kinase as compared with the low Km for 5-chlorodeoxycytidine (1.1 microM) accounts for the absence of antagonism of the antiviral activity. The high Km for 5-chlorodeoxycytidine (56 microM) as compared with the low Km of deoxycytidine (2 microM) with respect to mammalian deoxycytidine kinase accounts, in great part, for the antagonism of toxicity. In addition, antagonism of toxicity by deoxycytidine is the result of factors other than the kinetic parameters of nucleoside kinases, as indicated by its antagonism of the cytotoxicity of 5-chlorodeoxyuridine. This may be attributed to replenishment of low dCTP pools, diminished because of effector inhibition of ribonucleoside diphosphate reductase by Cl-dUTP. Resistance of the herpes-encoded enzymes to effector control may also play a role in the selective antagonism. Cell culture studies with high concentrations of tetrahydrouridine and 2'-deoxytetrahydrouridine suggest that competition by deoxycytidine for deaminases may not play a major role. The fact that deoxycytidine antagonizes the toxicity of chlorodeoxyuridine also argues against competition for the deaminases as a major reason for its effect. Limited studies with a topical herpes simplex virus type 2 infection system indicate heightened efficacy of 5-chlorodeoxycytidine (and tetrahydrouridine) when deoxycytidine is coadministered. The concepts of selective antagonism of a chemotherapeutic agent derived from these studies may be applied to other approaches that extent beyond viral chemotherapy.

The morphology of canine lymphatic valves

The architecture of 60 valves from thoracic ducts and from renal hilar and mesenteric collecting lymph vessels of dogs were studied by scanning electron microscopy as well as by light and transmission electron microscopy. All of the valves seen in hilar and mesenteric lymph vessels and most of those studied in the thoracic duct were bicuspid. An occasional tricuspid and one monocuspid valve was seen in the thoracic duct. The semilunar cusps of the valves extended from the vessel wall, to which they were attached, towards the valve outlet where adjacent cusps fused. Coincident to the area of fusion was the formation of mesenteric-like folds or buttresses that anchored the cusps to the vessel wall. These folds extended 50-100 micrometers beyond the cusp margins on the outflow side of the valve. The attachments of the cusps, buttresses, and vessel wall to one another resulted in the formation of postvalvular sinuses, such that raised intraluminal pressure downstream to valve areas would distend the sinuses, causing leaflet apposition and hence valvular closure. The morphology of the valves was such that they were not considered to provide any significant impediment to the antegrade flow of lymph.

Left ventricular function in sickle cell anemia: a noninvasive evaluation

There is controversy in the medical literature regarding the significance of "sickle cell cardiomyopathy." In an attempt to clarify this, we studied 14 patients with sickle cell anemia (age range 16 to 36 years) using simultaneous echocardiography and phonocardiography. The values of systolic time intervals and echocardiographic indices of left ventricular performance were similar to those reported for normal subjects and those with comparable degrees of anemia. We confirm a previous report of normal left ventricular function at rest in patients with sickle cell anemia and concur with the suggestion that a concomitant heart disease be considered in these patients when cardiac failure supervenes.

Devic's syndrome and systemic lupus erythematosus: a case report with necropsy

Systemic lupus erythematosus (SLE) rarely occurs coincident with demyelinating disease and, to our knowledge, only one previous case of Devic's syndrome with SLE has been reported.