Radiation-induced optic neuropathy: a magnetic resonance imaging study

Optic neuropathy induced by radiation is an infrequent cause of delayed visual loss that may at times be difficult to differentiate from compression of the visual pathways by recurrent neoplasm. The authors describe six patients with this disorder who experienced loss of vision 6 to 36 months after neurological surgery and radiation therapy. Of the six patients in the series, two had a pituitary adenoma and one each had a metastatic melanoma, multiple myeloma, craniopharyngioma, and lymphoepithelioma. Visual acuity in the affected eyes ranged from 20/25 to no light perception. Magnetic resonance (MR) imaging showed sellar and parasellar recurrence of both pituitary adenomas, but the intrinsic lesions of the optic nerves and optic chiasm induced by radiation were enhanced after gadolinium-diethylenetriaminepenta-acetic acid (DTPA) administration and were clearly distinguishable from the suprasellar compression of tumor. Repeated MR imaging showed spontaneous resolution of gadolinium-DTPA enhancement of the optic nerve in a patient who was initially suspected of harboring recurrence of a metastatic malignant melanoma as the cause of visual loss. The authors found the presumptive diagnosis of radiation-induced optic neuropathy facilitated by MR imaging with gadolinium-DTPA. This neuro-imaging procedure may help avert exploratory surgery in some patients with recurrent neoplasm in whom the etiology of visual loss is uncertain.

Effects of neuropeptide Y (NPY) on the release of anterior pituitary hormones in the rat

Neuropeptide Y (NPY) has been recently localized in several hypothalamic nuclei in the mammalian brain. In order to investigate the possible role of NPY on neuroendocrine function, we have investigated the effects of the peptide on the release of anterior pituitary hormones in the rat. Both intravenous (300 micrograms) or intraventricular (2 to 15 micrograms) injection of NPY produced in gonadectomized male rats a significant and long-lasting decrease of plasma LH levels. A short duration stimulating effect on prolactin plasma levels was also observed after the intravenous but not after the intraventricular injection of NPY. Plasma levels of the other pituitary hormones were not significantly modified after NPY injection. When incubated in vitro with anterior pituitary cells in monolayer culture, NPY produced no significant change in release of pituitary hormones. Thus NPY seems to exert a selective effect on LH release. Since this effect can be observed after both intravenous and intraventricular injection, it might be hypothesized that NPY could affect LHRH release in two areas which lack blood-brain barrier: the organum vasculosum of the lamina terminalis (OVLT) which contains LHRH cell bodies and NPY fibers and the median eminence which contains both LHRH and NPY fibers. The effect on prolactin release needs to be carefully evaluated in different experimental conditions.

Neuropeptide Y in the intermediate lobe of the frog pituitary acts as an alpha-MSH-release inhibiting factor

The presence of neuropeptide tyrosine (NPY) in the intermediate lobe of the frog pituitary was demonstrated using indirect immunofluorescence, the immunogold technique and a specific radioimmunoassay combined with high pressure liquid chromatography (HPLC). A high density of NPY-containing fibers, was found among the parenchymal cells of the intermediate lobe. These fibers originated from the ventral infundibular nucleus, travelled via the median eminence to the pars intermedia. At the electron microscopic level, NPY-like material was found exclusively in nerve fibers where the product of the immunoreaction was associated to dense-core vesicles. High concentrations of NPY-like peptide were found in neurointermediate lobe extracts. After Sephadex G-50 gel filtration the major peak of immunoreactive material appeared to co-elute with synthetic porcine NPY. Conversely, HPLC analysis revealed that the NPY-like peptide of the frog pituitary had a retention time shorter than the porcine NPY. The localization of NPY-like material in the pars intermedia suggested a possible role of NPY in the regulation of melanotropic cell secretion. In fact, graded concentrations of synthetic NPY induced a dose-dependent inhibition of alpha-melanotropin (alpha-MSH) release in vitro. The lack of effect of a dopaminergic antagonist on NPY-induced alpha-MSH release inhibition demonstrated that the local dopaminergic system could not account for the NPY action. These results indicate that NPY located in the hypothalamo-hypophyseal system of the frog may act as a melanotropin-release inhibiting factor.

Noncontact Laser Doppler Imaging in Burn Depth Analysis of the Extremities

The purpose of this study was to determine the accuracy and practical utility of a noncontact laser Doppler imager (PIM-II, Lisca Development AB, Linköping, Sweden) in the estimation of burn depth in the upper and lower extremities. At 48 hours after burn injury, we performed scans of 35 burns in 22 patients and obtained histological samples for burn determination with hematoxylin and eosin and vimentin immunohistochemical staining. Additionally, sequential scans and tissue specimens were obtained on 10 burns at 24, 48, and 72 hours. A statistically significant inverse relationship was noted between burn depth and the laser Doppler perfusion index. Laser Doppler perfusion index values greater than 1.3 predicted a superficial dermal burn with 95% sensitivity and 94% specificity. Superficial dermal burns exhibited increased perfusion in the early burn period. Wounds showed a progressive decline in perfusion and a progressive increase in the depth of injury during a 72-hour period. This study demonstrates the advantage and accuracy of using a noncontact laser Doppler to differentiate deep dermal from superficial partial thickness burns in the extremities.

The Impact of a Normoglycemic Management Protocol on Clinical Outcomes in the Trauma Intensive Care Unit

BACKGROUND

The purpose of this study was to determine if protocol-driven normoglycemic management in trauma patients affected glucose control, ventilator-associated pneumonia, surgical-site infection, and inpatient mortality.

METHODS

A prospective, consecutive-series, historically controlled study design evaluated protocol-driven normoglycemic management among trauma patients at Vanderbilt University Medical Center. Those mechanically ventilated > or =24 hours and > or =15 years of age were included. A glycemic-control protocol required insulin infusion therapy for glucose >110 mg/dL. Control patients included those who met criteria, were admitted the year preceding protocol implementation, and had hyperglycemia treated at the physician's discretion.

RESULTS

Eight hundred eighteen patients met study criteria; 383 were managed without protocol; 435 underwent protocol. The protocol group had lower glucose levels 7 of 14 days measured. After admission, both groups had mean daily glucose levels <150 mg/dL. No difference in pneumonia (31.6% vs 34.5%; p = .413), surgical infection (5.0% vs 5.7%; p = .645) or mortality (12.3% vs 13.1%; p = .722) occurred between groups. If one episode of blood glucose level was > or =150 mg/dL (n = 638; 78.0%), outcomes were worse: higher daily glucose levels for 14 days after admission (p < .001), pneumonia rates (35.9% vs 23.3%; p = .002), and mortality (14.6% vs 6.1%; p = .002). One or more days of glucose > or =150 mg/dL had a 2- to 3-fold increase in the odds of death. Protocol use in these patients was not associated with outcome improvement.

CONCLUSIONS

Protocol-driven management decreased glucose levels 7 of 14 days after admission without outcome change. One or more glucose levels > or =150 mg/dL were associated with worse outcome.

Spectra of G ratio, myelin sheath thickness, and axon and fiber diameter in the guinea pig optic nerve

The spectra of fiber and axon diameter, myelin sheath thickness, fiber density, and g ratio of the optic nerve were analyzed for the strain-13 guinea pig, an animal extensively utilized in the investigation of experimental disorders of demyelination. Our detailed analytical study of the normal guinea pig optic nerve provides the basis for comparison to disease states and the morphology of other species. As in the rat, mouse, and chipmunk, fiber diameters in the guinea pig were unimodal, but dissimilar to the trimodal fiber spectra of the cat and primate. The predominance of medium-sized fibers (0.80-2.00 microns), common to most species, contributed to the larger mean fiber diameter (1.45 microns) of the guinea pig optic nerve, in which small fibers (0.50 microns or less) were infrequent and fibers larger than 5.00 microns in diameter, seen in the cat and primate, were absent. While myelin sheath thickness increased with axon diameter in the guinea pig, as in other species, a g ratio of 0.81 in the guinea pig was greater than in most mammals. Since conduction velocity is dependent on axon size, as well as myelin properties, the relatively larger mean axon diameter of the guinea pig optic nerve (1.18 microns) may compensate for the decrease in its myelination.

The expression of bacterial nitroreductase in transgenic mice results in specific cell killing by the prodrug CB1954

The enzyme nitroreductase, isolated from Escherichia coli B, converts CB1954 ((5-aziridin-1-yl)-2,4-dinitro-benzamide) into a cytotoxic DNA interstrand cross-linking agent. The E. coli B gene (nfnB, NTR) encoding nitroreductase (NTR) was cloned into eukaryotic expression vectors. When driven by a CMV promoter, 5-10% of the stably transfected mouse fibroblasts expressed the NTR enzyme. These cells were killed at a concentration of 20 microM CB1954 in comparison to nonexpressing cells which were killed at a much higher concentration (500 microM). We subsequently generated transgenic mice to test the prodrug system in vivo. Nitroreductase was expressed specifically in T cells driven by the control elements of the human CD2 locus. Upon CB1954 treatment, transgenic mice show extensive cell depletion in thymus and spleen (14-16% of normal cell numbers), whereas all other tissues are unaffected by prodrug administration. These results raise the possibility of using the NTR gene in anticancer therapy.

Localization and identification of alpha-melanocyte-stimulating hormone (alpha-MSH) in the frog brain

The distribution of alpha-melanocyte-stimulating hormone (alpha-MSH) in the central nervous system of the frog Rana ridibunda was determined by immunofluorescence using a highly specific antiserum. alpha-MSH-like containing perikarya were localized in the infundibular region, mainly in the ventral hypothalamic nucleus. A rich plexus of immunoreactive fibers directed towards the ventral telencephalic region was detected. Reverse-phase high-performance liquid chromatography and radioimmunoassay were used to characterize alpha-MSH-like peptides in the frog brain. Chromatographic separation revealed that immunoreactive alpha-MSH coeluted with synthetic des-N alpha-acetyl alpha-MSH, authentic alpha-MSH and their sulfoxide derivatives. The heterogeneity of alpha-MSH-like material in the frog brain was in marked contrast with the figure observed in the intermediate lobe of the pituitary gland where only des-N alpha-acetyl alpha-MSH is present. These findings support the existence of discrete alpha-MSH immunoreactive neurons in the frog brain containing both desacetyl and authentic alpha-MSH.

Differential projections of two immunoreactive alpha-melanocyte stimulating hormone (alpha-MSH) neuronal systems in the rat brain

Immunocytochemical localization of alpha-MSH was performed in the brain of rats of which the arcuate nucleus has been destroyed by treatment with monosodium glutamate in the neonatal period. In these animals, alpha-MSH cell bodies normally found in the arcuate nucleus were almost completely absent. The reactive fibers found in the ACTH-beta-LPH pathway were also markedly decreased. On the other hand, alpha-MSH cell bodies located in the dorsolateral hypothalamus as well as fibers located outside the ACTH-beta-LPH pathway were not decreased. These results strongly suggest that alpha-MSH cell bodies in dorsolateral hypothalamus have projections completely different from those located in the arcuate nucleus.

A psychiatric study of women with urgency and urgency incontinence

26 patients with frequency, urgency and urgency incontinence, without bladder or urethral abnormality, underwent psychiatric evaluation. They were divided into 2 groups according to the degree of neuroticism found. Treatment by group and individual psychotherapy showed that approximately one-third of the patients benefited considerably, one-third refused treatment or ceased prematurely and one-third improved slightly or not at all. The importance of excluding organic bladder or urethral disease prior to psychiatric assessment is stressed.

Endorsement by the primary care practitioner consistently improves participation in screening for colorectal cancer: a longitudinal analysis

OBJECTIVES

To investigate the effect of general practice (GP) and general practitioner (GPR) endorsement for faecal occult blood test (FOBT)-based screening on maintenance of participation in screening over four successive screening rounds.

SETTING

South Australian residents aged > or = 50 years.

METHODS

Random selection of four groups (n = 600 per group): one from the Commonwealth electoral roll (ER) and three from the combined patient lists of two collaborating GPs (GP1, GP2, GP3). Subjects were mailed offers to screen using a faecal immunochemical test over four successive rounds, spaced approximately 18 months apart. The GP1 and ER groups were invited to screen without any endorsement from a GPR or medical practice; GP2 invitees received an invitation indicating support for screening from their medical practice; and GP3 invitations were printed on practice letterhead and were signed by a GPR.

RESULTS

Multivariate analyses indicated that initial participation as well as re-participation over four successive rounds was significantly enhanced in the GP2 (39%, 42%, 45% and 44%) and GP3 groups (42%, 47%, 48% and 49%) relative to the ER group (33%, 37%, 40% and 36%). The analyses also indicated that 60-69 year olds were most likely to participate in all rounds (relative risk [RR] 1.49, 1.39, 1.43 and 1.25), and men were generally less likely to participate than women in all screening rounds (RR 0.86, 0.84, 0.80 and 0.83).

CONCLUSIONS

Associating a GPR or medical practice of recent contact with an invitation to screen achieves better participation and re-participation than does an invitation from a centralized screening unit. Furthermore, enhanced participation can be achieved by practice endorsement alone without requiring actual GPR involvement.

Treatment of visual loss in pseudotumor cerebri associated with uremia

Ten patients with pseudotumor cerebri associated with renal insufficiency had papilledema and elevated intracranial pressure, but neurologic examinations and CT were normal. The 40% frequency of severe visual loss, 20/100 or worse, was higher than expected for pseudotumor cerebri. While furosemide was effective in 3 patients with renal transplants, administration of corticosteroids to 2 other patients did not halt progressive loss of vision. The visual function of 2 patients deteriorated even after lumboperitoneal shunting. Five patients underwent fenestration of the optic nerve sheath. This procedure improved the visual acuity of 3 patients and stabilized vision in the others. While the pathogenesis of pseudotumor cerebri in renal insufficiency is unknown, optic nerve sheath fenestration is the surgical treatment of choice for visual loss unresponsive to medical therapy.

Serotonin innervation of neuropeptide Y-containing neurons in the rat arcuate nucleus

Structural non-synaptic appositions between serotonin (5-HT) nerve endings and neuropeptide Y (NPY)-containing neurons were demonstrated in the rat arcuate nucleus by means of a combined radioautographic and immunocytochemical detection of [3H]5-HT uptake sites and NPY-immunoreactivity. Such cellular relationships are proposed to constitute a morphological substrate for putative 5-HT/NPY interactions in neuroendocrine hypothalamus.

Adeno-associated viral-mediated catalase expression suppresses optic neuritis in experimental allergic encephalomyelitis

Suppression of oxidative injury by viral-mediated transfer of the human catalase gene was tested in the optic nerves of animals with experimental allergic encephalomyelitis (EAE). EAE is an inflammatory autoimmune disorder of primary central nervous system demyelination that has been frequently used as an animal model for the human disease multiple sclerosis (MS). The optic nerve is a frequent site of involvement common to both EAE and MS. Recombinant adeno-associated virus containing the human gene for catalase was injected over the right optic nerve heads of SJL/J mice that were simultaneously sensitized for EAE. After 1 month, cell-specific catalase activity, evaluated by quantitation of catalase immunogold, was increased approximately 2-fold each in endothelia, oligodendroglia, astrocytes, and axons of the optic nerve. Effects of catalase on the histologic lesions of EAE were measured by computerized analysis of the myelin sheath area (for demyelination), optic disc area (for optic nerve head swelling), extent of the cellular infiltrate, extravasated serum albumin labeled by immunogold (for blood-brain barrier disruption), and in vivo H2O2 reaction product. Relative to control, contralateral optic nerves injected with the recombinant virus without a therapeutic gene, catalase gene inoculation reduced demyelination by 38%, optic nerve head swelling by 29%, cellular infiltration by 34%, disruption of the blood-brain barrier by 64%, and in vivo levels of H2O2 by 61%. Because the efficacy of potential treatments for MS are usually initially tested in the EAE animal model, this study suggests that catalase gene delivery by using viral vectors may be a therapeutic strategy for suppression of MS.

Biological and immunological characterization of alpha-melanocyte-stimulating hormone (alpha-MSH) in two neuronal systems of the rat brain

Recent immunocytochemical studies have demonstrated the existence of two different neuronal systems containing alpha-MSH-like material in the brain: one originating from the arcuate nucleus and the other one from the dorsolateral hypothalamus. The aim of the present study was to further characterize alpha-MSH in these two discrete regions of the rat diencephalon. Intracerebroventricular administration of colchicine resulted in a marked decrease in the number of ACTH and beta-endorphin nerve fibers and a significant reduction in ACTH and beta-endorphin content in the dorsolateral hypothalamus. Conversely, colchicine treatment did not alter alpha-MSH, ACTH or beta-endorphin content in the arcuate nucleus and did not significantly affect alpha-MSH concentration in the dorsal region. Reverse-phase high-performance liquid chromatography showed that the major alpha-MSH-like compound localized in the dorsal hypothalamus co-migrated exactly with synthetic alpha-MSH, whereas the arcuate nucleus contained 5 peptides cross-reacting with alpha-MSH antibodies, 4 of them being different from standard alpha-MSH. Significant amounts of biologically active melanotropin, which migrated on Sephadex G-25 columns like synthetic alpha-MSH, were also detected in both the arcuate nucleus and dorsolateral hypothalamus. Taken together, these data demonstrate that the alpha-MSH cell bodies located in the dorsolateral hypothalamus specifically produce authentic alpha-MSH, whereas the alpha-MSH cell bodies in the arcuate nucleus also contain ACTH, beta-endorphin and several peptides immunologically related but not identical to alpha-MSH.

Enhancement and demyelination of the intraorbital optic nerve. Fat suppression magnetic resonance imaging

Conventional spin-echo magnetic resonance imaging (MRI) of intraorbital optic neuritis is hampered by the adjacent high signal and chemical shift artifact of orbital fat. Frequency-selective saturation pulse MRI reduces these problems and was used to determine its utility in evaluation of intraorbital optic neuritis. Eight consecutive patients with optic neuritis underwent MRI within 1 week of the onset of visual loss. Conventional MRI with T1, proton density, and T2 weighting and frequency-selective saturation pulse MRI with T1, proton density, and T2 weighting were performed. After administration of intravenous gadopentetate dimeglumine, T1-weighted conventional and frequency-selective saturation pulse MRI were performed. Frequency-selective saturation pulse MRI showed gadopentetate dimeglumine enhancement in the intraorbital optic nerve in 7 patients and the intracranial optic nerve in 3 patients. Conventional MRI failed to show optic nerve gadopentetate dimeglumine enhancement in patients with intraorbital lesions, but did show intracranial lesions. Frequency-selective saturation pulse MRI showed bilateral optic nerve enhancement in 3 patients with unilateral visual signs and symptoms. Proton density and T2-weighted conventional MRI of the brain showed no convincing signal aberrations in the optic nerves. In the MRI evaluation of intraorbital optic neuritis: (1) frequency-selective saturation pulse fat suppression MRI is superior to T1-weighted conventional MRI in the detection of gadopentetate dimeglumine enhancement; (2) frequency-selective saturation pulse proton density and T2-weighted MRI is superior to proton density and T2-weighted conventional MRI; (3) frequency-selective saturation pulse MRI showed gadopentetate dimeglumine enhancement as well as proton density/T2-weighted signal aberration in exactly the same portion of the intraorbital optic nerve.

Central retinal and posterior ciliary artery occlusion after particle embolization of the external carotid artery system

A 15-year-old boy underwent neuroradiologic embolization of the left internal maxillary artery with polyvinyl alcohol to stop traumatic epistaxis after failure of surgical clipping and nasal packing. Selective catheterization of the external carotid artery before embolization showed a faint choroidal blush. Although the procedure provided hemostasis, embolization to the central retinal artery and ciliary arteries resulted in loss of vision. The route of the emboli to the eye was via the anastomotic network of the lacrimal artery supplied by the external carotid artery system. Neuroradiologic embolization of the external carotid artery is an effective mode of therapy for dural-cavernous fistulas when fed by the external carotid artery system. Because the blood flow to the brain and eye is predominantly supplied by the internal carotid artery, embolization of the external carotid artery is considered relatively safe. The authors document the importance of recognition of the choroidal blush during selective external carotid artery angiography as a sign of collateral blood flow to the eye. Physicians and patients need to be aware of the risk of blindness as a complication of external carotid artery embolization when this sign is present.

Morphological correlates of serotonin-neuropeptide Y interactions in the rat suprachiasmatic nucleus: combined radioautographic and immunocytochemical data

The morphological substrate of putative serotonin (5-HT)/neuropeptide Y (NPY) interactions in the suprachiasmatic nucleus (SCN) was investigated by combined radioautography and immunocytochemistry after intraventricular administration of (3H)5-HT in the rat. In the ventral portion of the SCN, the distribution of (3H)5-HT uptake sites overlapped closely the NPY-immunoreactive terminals. Previous investigations have shown that the dense 5-HT and NPY innervations of the SCN originate in different structures, i.e., the midbrain raphe nuclei and the ventral lateral geniculate nucleus, respectively. Accordingly, in the present study, destruction of 5-HT afferents by 5,7-dihydroxytryptamine was not found to induce any modification in NPY staining and, in ultrastructural immuno-radioautographic preparations, two distinct pools of axonal varicosities could be identified. Both 5-HT and NPY terminals established morphologically defined synaptic junctions, sometimes on the same neuronal target. Some cases of direct axo-axonic appositions between the two types of terminals were also encountered. These data constitute additional criteria for characterizing the cytological basis of the multiple transmitter interactions presumably involved in the function of the SCN as a central regulator of circadian biological rhythms.

Contralateral trochlear nerve paresis and ipsilateral Horner's syndrome

Two patients had paresis of the trochlear nerve contralateral to the site of lesions in the brainstem. Both patients had ipsilateral blepharoptosis and miosis suggesting oculosympathetic paresis from involvement of the descending sympathetic tract, adjacent to the fourth cranial nerve nucleus and its fascicles, in the caudal mesencephalon. Cerebral antiography documented an arteriovenous malformation of the brainstem in Case 1. Magnetic resonance imaging disclosed a lesion of high signal intensity on T2-weighted images involving the dorsal mesencephalon in Case 2. Involvement of the superior cerebellar peduncle produced ipsilateral dysmetria and ataxia. Lesions involving the fourth cranial nerve nucleus or its fascicles, before decussation in the superior medullary velum, and adjacent sympathetic fibers may produce an ipsilateral Horner's syndrome and contralateral superior oblique muscle paresis.

Immunohistological demonstration of a substance related to neuropeptide Y and FMRFamide in the cephalic and thoracic nervous systems of the locust Locusta migratoria

A neuropeptide related to the mammalian neuropeptide Y (NPY) is present in various neurosecretory cells (NSC) of the cephalic and thoracic nervous systems of the insect Locusta migratoria. Immunoreactive perikarya are detected in the protocerebrum, tritocerebrum, optic lobes and the suboesophageal and thoracic ganglia. They give rise to many immunoreactive processes that ramify extensively throughout the neuropiles. In the brain, prominent axon bundles tightly surround the tractus I to the corpora cardiaca. This fiber pattern suggests that the NPY-like substance may have a neuromodulator and/or neurotransmitter function. This substance may also have a neurohormonal role, since some immunoreactive tracts penetrate into neurohaemal organs via the nervi corporis cardiaci II and the thoracic median nerves. NCS containing NPY-like neuropeptide also display an FMRFamide-like immunoreactivity (except for the abdominal part of the metathoracic ganglion). NPY or FMRFamide antisera are not inactivated after preabsorption with FMRFamide or NPY, respectively. It might therefore be inferred that in locust NSC these two antisera recognize two distinct antigenic sites belonging either to a large polypeptide, or to two distinct neuropeptides.