Pathologic features of cytomegalovirus retinopathy after treatment with the antiviral agent ganciclovir

Ganciclovir is a new antiviral compound (also called BW B759U, DHPG, BIOLF-62, and 2'NDG) that has been used for the treatment of cytomegalovirus (CMV) retinopathy in immunocompromised patients (bone marrow recipients or acquired immune deficiency syndrome [AIDS] victims). The authors studied the eyes of three AIDS patients with CMV retinopathy who died while receiving ganciclovir chemotherapy. Gross, microscopic, and ultrastructural studies of these cases showed varying degrees of retinal scarring and active CMV lesions at the margins of the scars. CMV antigens were localized in cells at all layers of retina at the border of the lesions and in isolated cells in a perivascular location within histologically normal appearing retina. These areas probably represent sites of recrudescence when the drug is discontinued. In situ hybridization using a cloned complementary DNA (cDNA) probe of human CMV corroborated the immunocytologic localization of the virus. Ultrastructural studies showed megalic syncytial cells containing mostly capsids exclusively in the cell nucleus. The cytoplasmic electron-dense membrane-bound bodies that have characterized untreated cases of CMV retinopathy were absent in the treated cases. An attempt to isolate CMV in tissue culture from the vitreous and retina of one of the cases yielded a negative result. Our results indicate that ganciclovir does not effectively eliminate CMV from the retina nor does it suppress expression of all viral genes. Ganciclovir appears to function by limiting viral DNA synthesis and subsequent packaging of viral DNA into infectious units, thereby acting as a virostatic chemotherapeutic agent.     

Biochemical actions of chronic ethanol exposure in the mesolimbic dopamine system

In previous studies, we have demonstrated that chronic administration of morphine or cocaine produces some common biochemical adaptations in the ventral tegmental area (VTA) and nucleus accumbens (NAc), components of the mesolimbic dopamine system implicated in the reinforcing actions of these and other drugs of abuse. Since this neural pathway is also implicated in the reinforcing actions of ethanol, it was of interest to determine whether chronic ethanol exposure results in similar biochemical adaptations. Indeed, as seen for chronic morphine and cocaine treatments, we show here that chronic ethanol treatment increased levels of tyrosine hydroxylase and glial fibrillary acidic protein immunoreactivity, and decreases levels of neurofilament protein immunoreactivity, in the VTA. Also like morphine and cocaine, ethanol increases levels of cyclic AMP-dependent protein kinase activity in the NAc. These actions of ethanol required long-term exposure to the drug, and were in most cases not seen in the substantia nigra or caudate-putamen, components of the nigrostriatal dopamine system studied for comparison. Altered levels of tyrosine hydroxylase in catecholaminergic cells frequently reflect altered states of activation of the cells. Moreover, increasing evidence indicates that ethanol produces many of its acute effects on the brain by regulating NMDA glutamate and GAB_A receptors. We therefore examined the influence of chronic ethanol treatment on levels of expression of specific glutamate and GABA receptor subunits in the VTA. It was found that long-term, but not short-term, ethanol exposure increased levels of immunoreactivity of the NMDARl subunit, an obligatory component of NMDA glutamate receptors, and of the Glu Rl subunit, a component of many AMPA glutamate receptors; but at the same time, long-term ethanol exposure decreased immunoreactivity levels of the α1 subunit of the GABA_A receptor complex. These changes are consistent with an increased state of activation of VTA neurons inferred from the observed increase intyrosine hydroxylase (TH) expression. These results demonstrate that chronic ethanol exposure results in several biochemical adaptations in the mesolimbic dopamine system, which may underlie prominent changes in the structural and functional properties of this neural pathway related to alcohol abuse and alcoholism. © 1995 Wiley-Liss, Inc.     

The distribution and possible function of gamma interferon-immunoreactive cells in normal endometrium and myometrium

Summary T-lymphocytes are present in normal endometrium, where they may have a role in the control of glandular maturation. T-cell activity could be related to the local secretion of cytokines such as gamma interferon, which has an anti-proliferative effect on endometrial epithelial cells in vitro. We have examined gamma interferon immunoreactivity and T-cell distribution in 24 normal pre-menopausal uteri. Endometrial appearances were representative of all stages of the menstrual cycle. Most cells in the lymphoid aggregates in the stratum basalis were stained by T-cell and gamma interferon antisera. T-lymphocytes were also scattered in glandular epithelium and throughout the stroma of basal and functional layers; immunoreactivity for gamma interferon was less consistent in these cells. There was no alteration in the intensity or distribution of gamma interferon staining in different phases of the menstrual cycle. Endometrial granulocytes (K-cells) present mainly in the late secretory endometria were not reactive with the gamma interferon antiserum. In addition to endometrial staining, T-cells were distributed in all areas of the myometrium in most uteri, and many myometrial lymphocytes were gamma interferon positive. These results support a role for gamma interferon in endometrial physiology, possibly as an inhibitor of epithelial proliferation.     

Psychopathological traits and 5-HT2A receptor promoter polymorphism (-1438 G/A) in patients suffering from Anorexia Nervosa and Bulimia Nervosa

Various studies have evaluated the possible role of the -1438G/A polymorphism within the 5-HT2A receptor gene in the susceptibility to Eating Disorders (EDs). One hundred and forty-eight ED patients (EDp) and 89 control subjects were interviewed by means of the Eating Disorder Examination (EDE) and analyzed for distribution of the -1438G/A polymorphism. Patients with the AA genotype suffering from Anorexia Nervosa and Bulimia Nervosa showed higher Weight and Shape Concern (P = 0.003 and P = 0.010, respectively) scores and greater overall severity of the ED psychopathology (EDE total score) (P = 0.012). The obtained preliminary data suggest the use of dimensional psychopathological measures in ED genetic studies.     

Marek's disease as a model for the Landry--Guillain--Barré syndrome: latent viral infection in nonneuronal cells accompanied by specific immune responses to peripheral nerve and myelin.

In the chicken, Marek's disease virus (MDV) induces a demyelinating peripheral neuropathy that, early in the course of the disease, is histopathologically indistinguishable from that seen in the Landry--Guillain--Barré syndrome in man. A continuing role for a productive infection in the pathogenesis of this disease is unlikely, since neither MDV nor MDV antigens can be characteristically detected in nerves or spinal ganglia examined at necropsy. The authors investigated the possible role of a latent viral infection by explanting and maintaining in vitro the sciatic nerves and spinal ganglia from diseased birds. In these tissues, viral specific products were induced and detected by immunofluorescence and ultrastructural methods early after explanation in well-isolated Schwann cells, satellite cells, and lymphocytes. Later, virus was detected in fibroblasts, macrophages, and neoplastic lymphoblastoid cells. Neurons and myelinating Schwann cells, in contrast, did not replicate the agent. Specific cell-mediated and humoral immune responses to chicken peripheral nerve and peripheral nerve myelin were demonstrated early in the course of the disease. When considered relative to potential pathogenetic mechanisms, these results suggest that Marek's disease neuropathy is initiated by the establishment of a latent viral infection in neuronal supporting cells. A specific immune response to viral-induced antigens on these cells could, in turn, result in subsequent demyelination.     

Effects of chronic stress on the development of histamine enzymes

The activity of histidine-decarboxylase (HD) and histamine-N-methyl-transferase (HMT) was studied in the hypothalamus and cerebral cortex of rats from birth to adulthood. Development patterns were compared in sea-level controls and in rats born and maintained continuously in a natural hypoxic environment (at a high altitude of 3800 m, P_{O 2} 13%) to determine whether chronic stress alters the development of the enzymes for histamine. When expressed in terms of total activity, both enzyme activities were low at birth and progressively increased with age in the two areas studied. When expressed in terms of specific activity, the developmental pattern of the enzymes better reflected that of histamine: for example, at birth, high HD activity and low HMT corresponded to high histamine levels; at 7 days, low HD activity and high HMT corresponded to low histamine levels. It is suggested that a feedback mechanism may operate between endogenous histamine levels and the activity of its synthesizing and catebolizing enzymes.Exposure to chronic stress failed to alter enzymatic activity during the first postnatal week, but significantly influenced it in later development and adulthood. In the hypothalamus stress induced HD activity in the developing animals but depressed it in the adults. In the cerebral cortex, HMT rather than HD was stimulated by stress, but here again the effects were age-dependent. The sensitivity of histaminergic enzymes to environmental stimulation provides indirect supportive evidence for neurotransmitter role of histamine.     

Impact of 970 nm photobiomodulation therapy on wound healing in cellular models of hidradenitis suppurativa

Lasers in Medical Science -     

Demonstration of pro-opiomelanocortin mRNA in pituitary adenomas and para-adenomatous gland in cushing's disease and Nelson's syndrome

Pro-opiomelanocortin (POMC) mRNA was demonstrated in pituitary adenomas from 16 patients with Cushing's disease and 10 with Nelson's syndrome. The intensity of signal was significantly greater in Nelson's syndrome than in Cushing's disease and there was a trend towards a greater proportion of positive cells. This probably reflects inhibition of POMC gene expression by the high circulating levels of cortisol in Cushing's disease. In the para-adenomatous gland, the intensity of signal was variable in cells showing Crooke's hyaline change, ranging from negative to strongly positive, in keeping with the functional heterogeneity of corticotrophs. In one case, junctional corticotrophs were present and these were more intensely stained than anterior lobe corticotrophs in the same gland. This supports the concept that these cells are subject to different regulatory influences from corticotrophs in the anterior lobe. Whether this is related to differences in embryological origins or to local factors is at present unclear.     

Serotonergic inhibition of the mossy fibre—granule cell glutamate transmission in rat cerebellar slices

Summary The glutamatergic mossy fibre granule cell pathway has been investigated in rat cerebellar slices. Exposure to 35 mM KCI, a concentration of K⁺ known to elicit Ca²⁺-dependent releases of excitatory amino acids from cerebellar slices, raised cGMP levels. The cGMP response was decreased in a concentration-dependent manner by D-(–)-2-amino-5-phosphonopentanoic acid (D-AP5) and by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) indicating the involvement of ionotropic glutamate receptors of both the N-methyl-D-aspartate (NMDA) and the non-NMDA type. The K⁺-evoked production of cGMP was potently inhibited (EC₅₀ = 1.21 nM) by 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), a selective 5-HT₂ receptor agonist. The effect of DOI (0.01 M) was antagonized by 0.03 M of the 5-HT₂ receptor antagonists ketanserin and methiothepin. At concentrations higher than 0.1 M, both antagonists increased on their own the cGMP response elicited by high-K⁺. This effect was insensitive to tetrodotoxin.It had been previously shown that rat mossy fibre endings release glutamate upon depolarization and that such release can be inhibited by activation of 5-HT₂ receptors sited on the mossy fibre endings. Altogether the available data suggest the following conclusions: (a) the glutamate/aspartate endogenously released in cerebellar slices during K⁺ depolarization increase cGMP synthesis through the activation of both NMDA and non-NMDA receptors; (b) a portion of the cGMP response can be prevented by 5-HT₂ receptor activation and may reflect the activity of the mossy fibre-granule cell pathway. Thus serotonin is likely to exert a potent inhibitory control of the excitatory mossy fibre input to the cerebellum by acting at receptors of the 5-HT₂ type. Correspondence to M. Raiteri at the above address