Primary Site Of Damage Research Articles

Neuroanatomy and neuropathology associated with Korsakoff's syndrome.

Although the neuropathology of Korsakoff's syndrome (KS) was first described well over a century ago and the characteristic brain pathology does not pose a diagnostic challenge to pathologists, there is still controversy over the neuroanatomical substrate of the distinctive memory impairment in these patients. Cohort studies of KS suggest a central role for the mammillary bodies and mediodorsal thalamus, and quantitative studies suggest additional damage to the anterior thalamus is required. Rare cases of KS caused by pathologies other than those of nutritional origin provide support for the role of the anterior thalamus and mammillary bodies. Taken together the evidence to date shows that damage to the thalamus and hypothalamus is required, in particular the anterior thalamic nucleus and the medial mammillary nucleus of the hypothalamus. As these nuclei form part of wider memory circuits, damage to the inter-connecting white matter tracts can also result in a similar deficit as direct damage to the nuclei. Although these nuclei and their connections appear to be the primary site of damage, input from other brain regions within the circuits, such as the frontal cortex and hippocampus, or more distant regions, including the cerebellum and amygdala, may have a modulatory role on memory function. Further studies to confirm the precise site(s) and extend of brain damage necessary for the memory impairment of KS are required.

Secondary Neurodegeneration in Remote Regions After Focal Cerebral Infarction

Cerebral infarction-induced cessation of function in areas of the brain remote from, but connected to, the primary site of damage was termed “diaschisis” by von Monakow.1 Initially, the concept of diaschisis did not include morphological changes. However, accumulating evidence has shown that histopathologic changes also occur in nonischemic remote brain regions that have synaptic connections with the primary lesion site. For example, after cerebral infarction in the middle cerebral artery (MCA) territory, neuronal death, gliosis, and axonal degeneration have been found in the ipsilateral thalamus, substantia nigra (SN), and distal pyramidal tract, all of which lie outside the MCA territory.2–7 This kind of secondary neurodegeneration occurs selectively in such areas several days or weeks after stroke onset, and this can be detected by neuroimaging techniques.8 For quite a long time, the role of secondary degeneration in stroke recovery has not been well understood. Recently, emerging studies suggest that secondary degeneration is associated with neurological deficits and can predict motor outcome after stroke.9–15 In this review, we aimed to summarize the pathological and neuroimaging evidence of secondary neurodegeneration in the ipsilateral thalamus, SN, and pyramidal tract after MCA infarction and described its potential significance for stroke management. We searched PubMed from 1980 to September 2011, using the terms “cerebral infarction,” “middle cerebral artery,” “Wallerian degeneration,” “anterograde degeneration,” “retrograde degeneration,” and “transneuronal degeneration.” Further articles were identified from the references cited in those articles and through searches of our personal files. The final list of references was selected on the basis of originality and relevance to the topics covered in this review. ### Postmortem Studies Data from postmortem studies provide direct evidence of secondary neurodegeneration after focal cerebral infarction (Figure 1). Histopathologic examination at 4 months after MCA infarction revealed a delayed and selective decrease in the …

Sensory Guillain–Barré syndrome and related disorders: An attempt at systematization

The possibility that some patients diagnosed with an acute sensory neuropathy could actually have Guillain-Barré syndrome (GBS) has been repeatedly advanced in the literature, but the number of cases reported is small. The reports have shown different clinical presentations and electrophysiological findings and are variously named, thus generating terminological and nosological confusion. We operatively defined sensory GBS as an acute, monophasic, widespread neuropathy characterized clinically by exclusive sensory symptoms and signs that reach their nadir in a maximum of 6 weeks without related systemic disorders and other diseases or conditions. We reviewed the literature through searches of PubMed from 1980 to March 2011 and our own files. On the basis of the size of fibers involved and the possible site of primary damage, we propose tentatively classifying sensory GBS and related disorders into three subtypes: acute sensory demyelinating polyneuropathy; acute sensory large-fiber axonopathy-ganglionopathy; and acute sensory small-fiber neuropathy-ganglionopathy.

Photoinhibition: molecular mechanisms and physiological significance

Photoinhibition: molecular mechanisms and physiological significance

Flubendazole and ivermectin in vitro combination therapy produces a marked effect on Echinococcus granulosus protoscoleces and metacestodes

The aim of the present work was to evaluate the in vitro efficacy of the flubendazole (FLBZ) and ivermectin (IVM) combination against Echinococcus granulosus protoscoleces and metacestodes. Protoscoleces and groups of ten peritoneal cysts obtained from BALB/c mice were incubated with the two drugs, either separately or in combination, at the following final concentrations: 10 microg/mL FLBZ, 1 microg/mL FLBZ, 1 microg/mL IVM, 10 microg/mL FLBZ + 1 microg/mL IVM, and 1 microg/mL FLBZ + 1 microg/mL IVM. The maximum protoscolicidal effect was found with the combination 10 microg/mL FLBZ + 1 microg/mL IMV. After 1 day of incubation, the presence of numerous blebs in the tegument of protoscoleces was observed. Ultrastructural studies revealed that the primary site of damage was the tegument of the parasite. The effect of the two drugs on hydatid cysts obtained from mice was more rapidly detected in cysts treated with the combination of FLBZ + IVM than when drugs were used separately. Ultrastructural studies revealed that the germinal layer of treated cysts lost the multicellular structure feature and underwent considerable degenerative changes after in vitro treatment. The outcomes obtained demonstrated the favorable effect of the combination of FLBZ and IVM against E. granulosus.

Peripapillary and Posterior Scleral Mechanics—Part II: Experimental and Inverse Finite Element Characterization

The posterior sclera likely plays an important role in the development of glaucoma, and accurate characterization of its mechanical properties is needed to understand its impact on the more delicate optic nerve head--the primary site of damage in the disease. The posterior scleral shells from both eyes of one rhesus monkey were individually mounted on a custom-built pressurization apparatus. Intraocular pressure was incrementally increased from 5 mm Hg to 45 mm Hg, and the 3D displacements were measured using electronic speckle pattern interferometry. Finite element meshes of each posterior scleral shell were reconstructed from data generated by a 3D digitizer arm (shape) and a 20 MHz ultrasound transducer (thickness). An anisotropic hyperelastic constitutive model described in a companion paper (Girard, Downs, Burgoyne, and Suh, 2009, "Peripapillary and Posterior Scleral Mechanics--Part I: Development of an Anisotropic Hyperelastic Constitutive Model," ASME J. Biomech. Eng., 131, p. 051011), which includes stretch-induced stiffening and multidirectional alignment of the collagen fibers, was applied to each reconstructed mesh. Surface node displacements of each model were fitted to the experimental displacements using an inverse finite element method, which estimated a unique set of 13 model parameters. The predictions of the proposed constitutive model matched the 3D experimental displacements well. In both eyes, the tangent modulus increased dramatically with IOP, which indicates that the sclera is mechanically nonlinear. The sclera adjacent to the optic nerve head, known as the peripapillary sclera, was thickest and exhibited the lowest tangent modulus, which might have contributed to the uniform distribution of the structural stiffness for each entire scleral shell. Posterior scleral deformation following acute IOP elevations appears to be nonlinear and governed by the underlying scleral collagen microstructure as predicted by finite element modeling. The method is currently being used to characterize posterior scleral mechanics in normal (young and old), early, and moderately glaucomatous monkey eyes.

Immunocytochemical Traits of Type IV Fibrocytes and Their Possible Relations to Cochlear Function and Pathology

One of the more consistent and least understood changes in the aging human cochlea is the progressive loss of fibrocytes within the spiral ligament. This report presents an animal model for type IV fibrocyte loss, along with immunocytochemical evidence that noise-induced loss of these cells may account for previously unexplained hearing losses. The remarkably low threshold for noise-induced loss of type IV fibrocytes, approximately 24 dB less than the threshold for adjacent hair cell destruction, may account for the prevalence of missing fibrocytes in humans. In mice, changes in the spectrum of traumatizing noise had little effect upon the site of loss of the fibrocytes, suggesting that the primary site of damage that induced the loss was the basal-most cochlear turn, a site expected to be damaged by all three noise bands. Type IV fibrocytes were found to immunostain for connective tissue growth factor (CTGF) and for transforming growth factor beta receptor 3, a receptor that is known to activate CTGF expression. Type IV fibrocytes lack immunostaining for adenosine triphosphatase and connexins that are key players in potassium ion uptake and transmission, which suggests that they play little, if any, role in potassium recycling from perilymphatic space to the endolymphatic space. Consequently, their loss probably does not directly reduce this process. Immunostaining for a receptor for CTGF, low-density-lipoprotein-related protein 1, indicated that CTGF acts as an autocrine and a paracrine agent within the cochlea. The lack of CTGF paracrine effects following noise-induced loss of type IV fibrocytes may account for previously unexplained hearing losses.

Activation of Stretch-Activated Channels and Maxi-K+Channels by Membrane Stress of Human Lamina Cribrosa Cells

The lamina cribrosa (LC) region of the optic nerve head is considered the primary site of damage in glaucomatous optic neuropathy. Resident LC cells have a profibrotic potential when exposed to cyclical stretch. However, the mechanosensitive mechanisms of these cells remain unknown. Here the authors investigated the effects of membrane stretch on cell volume change and ion channel activity and examined the associated changes in intracellular calcium ([Ca(2+)](i)). The authors used primary LC cells obtained from normal human donor eyes. Confocal microscopy was used to investigate the effect of hypotonic cell membrane stretch on cell volume changes. Whole-cell patch-clamp and calcium imaging techniques were used to investigate the effect of hypotonicity on ion channel(s) activity and [Ca(2+)](i) changes, respectively. RT-PCR was used to examine for the maxi-K(+) signature in LC cells. In this study, LC cells showed significant volume changes in response to hypotonic cell swelling. The authors characterized a large conductance K(+) channel (maxi-K(+)) in LC cells and demonstrated its increased activity during cell membrane hypotonic stretch. RT-PCR revealed the presence of maxi-K(+) signature in LC cells. The authors showed the [Ca(2+)](i) and maxi-K(+) channels to be dependent on extracellular Ca(2+) and inhibited by gadolinium, which blocks stretch-activated channels (SACs). Pretreatment with thapsigargin, which blocks the release of Ca(2+) from endoplasmic reticulum stores, showed no significant difference in [Ca(2+)](i) concentration on hypotonic swelling. The results show that hypotonic stress of human LC cells activates SAC and Ca(2+)-dependent maxi-K(+) channels and that the increase in [Ca(2+)](i) during cell swelling was predominantly from extracellular sources (or intracellular stores other than the endoplasmic reticulum). These findings improve the understanding of how LC cells respond to cell membrane stretch. Further experiments in this area may reveal future targets for novel therapeutic intervention in the management of glaucoma.

IMPACT OF BLEACHING STRESS ON THE FUNCTION OF THE OXYGEN EVOLVING COMPLEX OF ZOOXANTHELLAE FROM SCLERACTINIAN CORALS(1).

Global climate change is leading to the rise of ocean temperatures and is triggering mass coral bleaching events on reefs around the world. The expulsion of the symbiotic dinoflagellate algae is believed to occur as a result of damage to the photosynthetic apparatus of these symbionts, although the specific site of initial impact is yet to be conclusively resolved. Here, the sensitivity of the oxygen evolving complex (OEC) to bleaching stress was studied as well as its natural variation between seasons. The artificial electron donor, diphenyl carbazide (DPC), was added to cultured, freshly isolated and expelled (bleaching treatments only) zooxanthellae suspensions. Chl a fluorescence and oxygen production measurements showed that upon addition of DPC, no restoration of diminished photochemical efficiency occurred under control or bleaching conditions. This result was consistent between 12 h and 5 d bleaching treatments on Pocilloporadamicornis, indicating that the OEC is not the primary site of damage, and that zooxanthellae expulsion from the host is a nonselective process with respect to the functioning of the OEC. Further experiments measuring fast induction curves (FICs) revealed that in both summer and winter, the temperature when OEC function was lost occurred between 7°C and 14°C above the sea surface temperature. FIC and oxygen production measurements of P. damicornis during exposure to bleaching stress demonstrated that the thermotolerance of the OEC increased above the temperature of the bleaching treatment over a 4 h period. This finding indicates that the OEC has the capacity to acclimate between seasons and remains functional at temperatures well above bleaching thresholds.

Efficacy of thymol against Echinococcus granulosus protoscoleces

The aim of the present work was to determine the in vitro protoscolicidal effect of thymol against Echinococcus granulosus. Protoscoleces of E. granulosus were incubated with thymol at concentrations of 10, 5 and 1 μg/ml. The first signs of thymol-induced damage were observed between 1 and 4 days post-incubation. The maximum protoscolicidal effect was found with thymol at 10 μg/ml, viability reduced to 53.5±11.9% after 12 days of incubation. At day 42, viability was 11.5±15.3% and, reached 0% after 80 days. Thymol at concentrations of 5 and 1 μg/ml provoked a later protoscolicidal effect. Results of viability tests were consistent with the tissue damage observed at the ultrastructural level. The primary site of damage was the tegument of the parasite. The morphological changes included contraction of the soma region, formation of blebs on the tegument, rostellar disorganization, loss of hooks and destruction of microtriches. The data reported in this article demonstrate a clear in vitro effect of thymol against E. granulosus protoscoleces.

Through the eye of a book... on the eye

The retina is perhaps our most intricate and well-studied sensory structure. It receives visual information from the outside world and interprets this information as color, shape and movement, and then transmits it to visual centers in the brain in the form of coded impulses. The embryonic and early

Mesna or cysteine prevents chloroacetaldehyde-induced cell death of human proximal tubule cells

Chloroacetaldehyde (CAA) is formed in the body from the chemotherapeutically used drug ifosfamide (IFO). CAA leads to cell death in proximal tubule cells mainly through the mechanism of necrosis rather than apoptosis. During chemotherapy, 2-mercaptosulfonic acid (mesna) is used with IFO to protect the urothel from cell damage. Little is known of the effect of mesna on renal proximal tubule cells, the primary site of damage after IFO treatment. Mesna contains a sulfhydryl (SH) group. To clarify whether SH-group-containing molecules can prevent CAA-induced cell death, we studied the effect of mesna and cysteine on necrosis, apoptosis, and protein content in a human proximal tubule-derived cell line (IHKE cells) treated with CAA. Both substances prevented CAA-induced necrotic cell death and protein loss and restored CAA-inhibited caspase-3 activity. CAA also prevented cisplatin-induced apoptosis. This inhibition was reversible in the presence of glutathione (GSH). We conclude that SH-containing molecules can protect proximal tubule cells from cell death because they interact with CAA before CAA can disturb other important cellular SH groups. A sufficient supply of intra- and extracellular SH groups during IFO chemotherapy may therefore have the ability to protect renal tubule cells from cell death.

Critical Pathways in Heart Function: Bis(2-chloroethoxy)methane-Induced Heart Gene Transcript Change in F344 Rats

Gene transcript changes after exposure to the heart toxin, bis(2-chloroethoxy)methane (CEM), were analyzed to elucidate mechanisms in cardiotoxicity and recovery. CEM was administered to 5-week-old male F344/N rats at 0, 200, 400, or 600 mg/kg by dermal exposure, 5 days per week, for a total of 12 doses by study day 16. Heart toxicity occurred after 2 days of dosing in all 3 regions of the heart (atrium, ventricle, interventricular septum) and was characterized by myofiber vacuolation, necrosis, mononuclear-cell infiltration, and atrial thrombosis. Ultrastructural analysis revealed that the primary site of damage was the mitochondrion. By day 5, even though dosing was continued, the toxic lesions in the heart began to resolve, and by study day 16, the heart appeared histologically normal. RNA was extracted from whole hearts after 2 or 5 days of CEM dosing. After a screen for transcript change by microarray analysis, dose-response trends for selected transcripts were analyzed by qRT-PCR. The selected transcripts code for proteins involved in energy production, control of calcium levels, and maintenance of heart function. The down-regulation of ATP subunit transcripts (Atp5j, ATP5k), which reside in the mitochondrial membranes, indicated a decrease in energy supply at day 2 and day 5. This was accompanied by down-regulation of transcripts involved in high-energy consumption processes such as membrane transport and ion channel transcripts (e.g., abc1a, kcnj12). The up-regulation of transcripts encoding for temperature regulation and calcium binding proteins (ucp1 and calb3) only at the 2 low exposure levels, suggest that these adaptive processes cannot occur in association with severe cardiotoxicity as seen in hearts at the high exposure level. Transcript expression changes occurred within 2 days of CEM exposure, and were dose-and time-dependent. The heart transcript changes suggest that CEM cardiotoxicity activates protective processes associated energy conservation and maintenance of heart function.

In vitro effects of flubendazole on Echinococcus granulosus protoscoleces

The aim of the present work was to determine the in vitro protoscolicidal effect of flubendazole (FLBZ) against Echinococcus granulosus. Protoscoleces of E. granulosus were incubated with FLBZ at concentrations of 10, 5 and 1 microg/ml. The first signs of FLBZ-induced damage were observed 3 days post-incubation. A clear protoscolicidal effect, reducing the vitality of protoscoleces to 35.6+/-0.7%, was observed after 18 days of incubation. After 25 days of FLBZ incubation (5 microg/ml), the percentage of vital protoscoleces was 13.9+/-5.9%. Protoscolex mortality was 100% (10 and 1 microg/ml) and 0.7+/-0.7% (5 microg/ml) after FLBZ incubation for 30 days. Results of vitality tests were consistent with the tissue damage observed at the ultrastructural level. The primary site of damage was the tegument of the parasite. The morphological changes included contraction of the soma region, formation of blebs on the tegument, rostellar disorganization, loss of hooks and destruction of microtriches. The data reported in this article demonstrate a clear in vitro effect of FLBZ against E. granulosus protoscoleces.

Comparative Safety Evaluation of the Candidate Vaginal Microbicide C31G

C31G is currently the focus of clinical trials designed to evaluate this agent as a microbicidal and spermicidal agent. In the following studies, the in vivo safety of C31G was assessed with a Swiss Webster mouse model of cervicovaginal toxicity and correlated with results from in vitro cytotoxicity experiments and published clinical observations. A single exposure of unformulated 1% C31G resulted in mild-to-moderate epithelial disruption and inflammation at 2 and 4 h postapplication. The columnar epithelium of the cervix was the primary site of damage, while no perturbation of the vaginal mucosa was observed. In contrast, application of unformulated 1.7% C31G resulted in greater levels of inflammation in the cervical epithelium at 2 h postapplication and severe epithelial disruption that persisted to 8 h postapplication. Application of a nonionic aqueous gel formulation containing 1% C31G resulted in no apparent cervicovaginal toxicity at any time point evaluated. However, formulation of 1.7% C31G did not substantially reduce the toxicity associated with unformulated C31G at that concentration. These observations correlate with findings gathered during a recent clinical trial, in which once-daily applications resulted in no adverse events in women receiving the formulation containing 1% C31G, compared to moderate-to-severe adverse events in 30% of women receiving the 1.7% C31G formulation. The Swiss Webster mouse model was able to effectively discriminate between concentrations and formulations of C31G that produced distinct clinical effects in human trials. The Swiss Webster animal model may be a highly valuable tool for preclinical evaluation of candidate vaginal microbicides.

Bis(2-chloroethoxy)methane-induced mitochondrial and myofibrillar damage: short-term time-course study.

Cardiotoxicity induced by 2-, 3-, 5-, and 12-day dermal administration of 400 and 600 mg/kg/day of bis(2-chloroethoxy)methane to F344/N male and female rats was characterized. The severity and incidence of lesions were similar among males and females and in all three regions of the heart examined (atrium, ventricle, interventricular septum). Damage induced by bis(2-chloroethoxy)methane consisted of time-related development of myofiber vacuolation, necrosis, mononuclear-cell infiltration, fibrosis, and atrial thrombosis. Changes were pronounced at day 2, increased in severity at day 3, appeared to decrease at day 5, and resolved by study-day 16 that corresponded to 12 dosings. Ultrastructural analysis of 2- and 5-day 600 mg/kg/day-treated females elucidated the primary site of damage, the mitochondrion, and two types of vacuolation, one that formed as damaged mitochondria became devoid of cristae and their bounding double membranes became reduced to singleness, and the other manifested as distention of the sarcoplasmic reticulum. After the initial damage induced by bis(2-chloroethoxy)methane, or its metabolite, thiodiglycolic acid, protective mechanisms within the heart were apparently initiated, enabling it to cope with the continued exposure to the toxicant while eliminating some damaged myofibers.

Tubulo-interstitial Disorders

<h2>Abstract</h2> Chronic renal failure (CRF) is accompanied by tubulo-interstitial atrophy and fibrosis, regardless of the cause. Disorders of the renal vasculature, the glomeruli or urinary drainage all culminate in chronic tubulo-interstitial damage, the severity of which is the histological feature that correlates best with progression to end-stage renal failure (ESRF). However, there are diverse conditions in which the tubulo-interstitium is the primary site of damage, and these may be considered together without inferring a common aetiology or pathogenesis. The diseases classified as tubulo-interstitial nephritis are considered below. Inherited disorders of tubular function are discussed in <i>MEDICINE</i> <b>31:5</b>, 32, acute tubular necrosis (ATN) in <i>MEDICINE</i> <b>31:6</b>, 43, and the renal manifestations of myeloma on page 99.

Endoplasmic reticulum and Golgi apparatus are the preferential sites of Foscan localisation in cultured tumour cells.

Intracellular photosensitiser localisation significantly influences the mechanism of response to photodynamic therapy (PDT), since the primary sites of damage are closely related to the specific sensitiser distribution. Foscan® subcellular localisation in the MCF-7 human adenocarcinoma cell line has been studied by means of confocal microscopy and microspectrofluorometry. The fluorescence topographic profiles recorded after cells costained with Foscan® and organelle-specific fluorescent probes revealed that Foscan® presents low localisation in lysosomes and a weak accumulation in mitochondria. Alternatively, the Foscan® fluorescence topographic profile turned out to colocalise perfectly with that obtained for the endoplasmic reticulum (ER) and the Golgi apparatus. The patterns of fluorescence derived from confocal microscopy studies were consistent with predominant localisation of Foscan® in these organelles. Furthermore, evaluation of enzymatic activity of selected organelles immediately after laser light irradiation (650 nm) indicated the Golgi apparatus and ER as the primary damaged sites resulting from Foscan®-mediated PDT in the MCF-7 cell line. To our knowledge, this is the first study to demonstrate unambiguously that the ER and the Golgi apparatus are preferential sites of Foscan® accumulation.

Morphologic characteristics of retinal degeneration induced by sodium iodate in mice

Purpose. Retinal degeneration induced by sodium iodate (NaIO3) in mice was evaluated morphologically. Methods. Male and female ICR and C57BL mice were intraperitoneally administered 100 mg/kg NaIO3 at 7 weeks of age, and were killed 6, 12, 24 hrs, and 3, 7 and 28 days after the treatment. Retinas were examined histologically, ultrastructurally, immunohistochemically, and by the TUNEL method. Results. Retinal degeneration was evoked in all NaIO3- treated mice. The primary site of damage appeared in the retinal pigment epithelial (RPE) cells followed by photoreceptor cell degeneration. Initially, the RPE cells showed necrosis starting 6 hrs post-NaIO3, followed by photoreceptor outer segment disruption and photoreceptor cell apoptosis at 24 hrs; photoreceptor cell apoptosis peaked at day 3 and was completed by day 7. At day 3, Müller cell proliferation, macrophage migration within the retina, and regeneration of damaged RPE cells occurred. Finally at day 7 and day 28, the retina showed a mosaic pattern of relatively normal retina and areas lacking RPE cells and photoreceptor cells. Conclusions. RPE cell necrosis followed by photoreceptor cell apoptosis and the resulting mosaic pattern of the retina phenotypically resembles gyrate atrophy of the choroid and retina.

Pathogenesis of male reproductive toxicity.

Toxicologic disturbance of male reproductive function can occur at many sites and produce a range of effects, some primary and some secondary to the initial insult. The challenge to the toxicological pathologist is to identify the primary site of damage and provide an insight into the pathogenesis of the morphologic lesion or functional deficit. Target sites include the testis, the epididymis, the mature sperm, and the hormonal regulatory system. Detection of effects at these varied sites requires the measurement of multiple endpoints only 1 of which is histopathology, but once identified, careful microscopic examination of the early changes in lesion development can provide essential information on the probable target cell and possible mechanisms of toxicity. Chemicals that affect different cell types or specific cellular functions generally elicit predictable patterns of pathological changes that can be readily recognized. Understanding the pathogenesis, the likely reversibility and the significance of reproductive tract lesions is aided by a sound knowledge of the physiology of the testis and epididymis and, in particular, an understanding of the timing of sperm production and transport.