Comparing remission and recurrence of hypertension after bariatric surgery: vertical sleeve gastrectomy versus Roux-en-Y gastric bypass.

BACKGROUND: Bariatric surgery results in rapid weight loss and resolution of many co-morbidities including hypertension. OBJECTIVES: To investigate the association of the 2 most common bariatric surgical procedures, vertical sleeve gastrectomy (VSG) and Roux-en-Y gastric bypass (RYGB), with sustained remission from hypertension, and evaluate other independent predictors of sustained remission. SETTING: Privately insured patients with hypertension in the United States undergoing bariatric surgery. METHODS: A cohort of hypertensive bariatric patients was created using detailed inclusion and exclusion criteria. Remission was defined as no refill of antihypertensive medication for 30 days after patients' medication was expected to run out, and recurrence as medication refill after at least 90 days of remission. RESULTS: Of 7006 patients in our cohort, 5874 experienced remission of their hypertension (83.8%). 745 of the 5874 (12.7%) patients later experienced recurrence. The adjusted hazard ratio of remission for VSG compared with RYGB was 1.06 (95% confidence interval [CI]; 1.0, 1.11). The adjusted hazard ratio of recurrence for VSG compared with RYGB was .84 (95% CI; .71, .97). A higher number of medications at the time of surgery was associated with a decreased likelihood of remission and an increased risk of recurrence of hypertension. CONCLUSION: There was no difference in the likelihood of remission of hypertension between VSG and RYGB. The number of medications at the time of surgery was the most important predictor of remission and recurrence of hypertension after surgery.

Adolescent bariatric surgery: a qualitative exploratory study of US patient perspectives.

Bariatric surgery is a safe and effective intervention to treat severe obesity and related comorbidities in adolescents. No qualitative studies have explored the perspectives of US adolescent weight-loss patients on their bariatric surgery motivations, decision-making or experiences. The purpose of this qualitative exploratory study was to explore the perspectives of adolescent patients seeking bariatric surgery while enrolled in a medical weight management programme. Eligible participants 13-21 years old were recruited through a weight management programme at a tertiary care children's hospital in the US Midwest. Interviews were conducted remotely using a video chat medium. An initial 60-min semi-structured interview was conducted with seven participants who were 16-21 years old: one deciding on bariatric surgery, one pre-operative and five post-operative. A brief follow-up interview was conducted 1 month later with four participants. Interviews were transcribed and coded using Atlas.ti software. Three broad themes emerged from participants' reflections: the long journey to surgery, time scarcity and be ready for change. The decision to pursue bariatric surgery takes place after struggling with obesity and failed weight-loss attempts since early childhood. Post-operative participants described bariatric surgery as life-changing, but determining when to schedule surgery is a challenge for adolescents.

The diagnostic accuracy of magnetic resonance venography in the detection of deep venous thrombosis: a systematic review and meta-analysis.

AIM: To search the literature for further evidence for the use of magnetic resonance venography (MRV) in the detection of suspected DVT and to re-evaluate the accuracy of MRV in the detection of suspected deep vein thrombosis (DVT). MATERIALS AND METHODS: PubMed, EMBASE, Scopus, Cochrane, and Web of Science were searched. Study quality and the risk of bias were evaluated using the QUADAS 2. A random effects meta-analysis including subgroup and sensitivity analyses were performed. RESULTS: The search resulted in 23 observational studies all from academic centres. Sixteen articles were included in the meta-analysis. The summary estimates for MRV as a diagnostic non-invasive tool revealed a sensitivity of 93% (95% confidence interval [CI]: 89% to 95%) and specificity of 96% (95% CI: 94% to 97%). The heterogeneity of the studies was high. Inconsistency (I2) for sensitivity and specificity was 80.7% and 77.9%, respectively. CONCLUSION: Further studies investigating the use of MRV in the detection of suspected DVT did not offer further evidence to support the replacement of ultrasound with MRV as the first-line investigation. However, MRV may offer an alternative tool in the detection/diagnosis of DVT for whom ultrasound is inadequate or not feasible (such as in the obese patient).

Proxy measures of vitamin D status - season and latitude - correlate with adverse outcomes after bariatric surgery in the Nationwide Inpatient Sample, 2001-2010: a retrospective cohort study.

OBJECTIVE: To investigate the association between adverse surgical outcomes following bariatric surgery and proxy measures of vitamin D (VitD) status (season and latitude) in the Nationwide Inpatient Sample (NIS). BACKGROUND: Obesity is an independent risk factor for VitD deficiency (25(OH)D < 20 ng ml-1). VitD deficiency compounds the chronic inflammation of obesity, increasing the risk of adverse outcomes following bariatric surgery. Epidemiology has long used season and latitude as proxies for group VitD, as VitD status is largely determined by sun exposure, which is greatest during summer and at the Equator. METHODS: We assessed proxy measures of group VitD status. We compared surgeries in VitD Summer (July to September), Winter (January to March), and Fall/Spring (October to December and April to June) and in the North (≥37°N) vs. the South (<37°N). RESULTS: We identified 932,091 bariatric surgeries; 81.2% were women and 74.4% were white. Sex was unequally distributed by season (p = 0.005). Median age was 43.0 years (all groups). Most surgeries occurred in the North (64.8%). Adverse outcome rates ranged from 0.01% (wound infections) to 39.4% [prolonged length of stay {LOS}]. Season was inversely associated with wound infection (p = 0.018) and dehiscence (p = 0.001). Extended LOS was inversely correlated with season (p < 0.001). These relationships held after adjustment. Prolonged LOS (p < 0.001) and any complication (p = 0.108) were more common in the North. CONCLUSIONS: We have demonstrated a graded relationship between seasonality and adverse outcomes following bariatric surgery. The association was strongest for dehiscence and prolonged LOS. These relationships held when using latitude. A prospective study measuring pre-operative 25(OH)D concentration would strengthen the case for causality in adverse surgical outcomes.

Effects of meal composition on postprandial incretin, glucose and insulin responses after surgical and medical weight loss.

BACKGROUND: Meal tolerance tests are frequently used to study dynamic incretin and insulin responses in the postprandial state; however, the optimal meal that is best tolerated and suited for hormonal response following surgical and medical weight loss has yet to be determined. OBJECTIVE: To evaluate the tolerability and effectiveness of different test meals in inducing detectable changes in markers of glucose metabolism in individuals who have undergone a weight loss intervention. METHODS: Six individuals who underwent surgical or medical weight loss (two Roux-en-Y gastric bypass, two sleeve gastrectomy and two medical weight loss) each completed three meal tolerance tests using liquid-mixed, solid-mixed and high-fat test meals. The tolerability of each test meal, as determined by the total amount consumed and palatability, as well as fasting and meal-stimulated glucagon-like peptide, glucose-dependent insulinotropic polypeptide, insulin and glucose were measured. RESULTS: Among the six individuals, the liquid-mixed meal was better and more uniformly tolerated with a median meal completion rate of 99%. Among the four bariatric surgical patients, liquid-mixed meal stimulated on average a higher glucagon-like peptide (percent difference: 83.7, 89), insulin secretion (percent difference: 155.1, 158.7) and glucose-dependent insulinotropic polypeptide (percent difference: 113.5, 34.3) compared with solid-mixed and high-fat meals. CONCLUSIONS: The liquid-mixed meal was better tolerated with higher incretin and insulin response compared with the high-fat and solid-mixed meals and is best suited for the evaluation of stimulated glucose homeostasis.

Aerosol exposure to the angola strain of marburg virus causes lethal viral hemorrhagic Fever in cynomolgus macaques.

Cynomolgus macaques were exposed to the Angola strain of Lake Victoria Marburg virus (MARV) by aerosol to examine disease course and lethality. Macaques became febrile 4 to 7 days postexposure; the peak febrile response was delayed 1 to 2 days in animals that received a lower dose; viremia coincided with the onset of fever. All 6 macaques succumbed to the infection, with the 3 macaques in the low-dose group becoming moribund on day 9, a day later than the macaques in the high-dose group. Gross pathologic lesions included maculopapular cutaneous rash; pulmonary congestion and edema; pericardial effusion; enlarged, congested, and/or hemorrhagic lymphoid tissues; enlarged friable fatty liver; and pyloric and duodenal congestion and/or hemorrhage. Fibrinous interstitial pneumonia was the most consistent pulmonary change. Lymphocytolysis and lymphoid depletion, as confirmed by TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling), were observed in the mediastinal lymph nodes and spleen. MARV antigen was detected in the lungs, mediastinal lymph nodes, spleen, and liver of all animals examined. In infected macaques, nuclear expression of interleukin-33 was lost in pulmonary arteriolar and mediastinal lymph node high endothelial venule endothelial cells; interleukin-33-positive fibroblastic reticular cells in the mediastinal lymph node were consistently negative for MARV antigen. These macaques exhibited a number of features similar to those of human filovirus infections; as such, this model of aerosolized MARV-Angola might be useful in developing medical countermeasures under the Animal Rule.

REVIEW PAPER: pathology of animal models of alphavirus encephalitis.

The encephalitides caused by Venezuelan (VEEV), eastern (EEEV), and western (WEEV) equine encephalitis viruses are important natural diseases of horses and humans and potential agents of biowarfare or bioterrorism. No licensed vaccines or specific therapies exist to prevent or treat human infections with VEEV, EEEV, or WEEV. Well-characterized animal models are needed to support the development of such medical countermeasures under the United States Food and Drug Administration's "Animal Rule." This review focuses on the pathological features and pathogenetic mechanisms of these alphaviral encephalitides in animal models, with an emphasis on aerosol infections. Infection of mice, nonhuman primates, and other species with VEEV, EEEV, and WEEV causes encephalitis and often death. There is great variability in the specific manifestations of disease in the different models, however. Many aspects of the disease in animal models and in humans remain to be characterized using modern methods. Especially needed is a better understanding of the fundamental mechanisms involved in 3 key phases of the pathogenesis of alphavirus encephalitis. These are the early extraneural phase, the process of neuroinvasion itself, and virus and host factors related to neurovirulence. A greater understanding of these aspects could provide avenues for the development of medical countermeasures and better establish suitable animal models of alphavirus encephalitis for testing them under the Animal Rule.

Multisystemic abscesses in African green monkeys (Chlorocebus aethiops) with invasive Klebsiella pneumoniae--identification of the hypermucoviscosity phenotype.

Invasive Klebsiella pneumoniae is an emerging disease of humans characterized by abscesses in the liver or other sites involving bacteria with the unique hypermucoviscosity phenotype. Over several months, 7 African green monkeys in our research colony developed abscess formation in multiple locations and succumbed to disease. K. pneumoniae was identified by bacterial culture in 6 monkeys and immunohistochemistry in 1 additional monkey. All monkeys had been housed in, or had contact with monkeys housed in, 1 animal room in our facility. All affected monkeys had 1 or more abscesses, most notably in the abdomen, but also affecting the lungs, cerebellum, and skin. Abdominal abscesses and associated adhesions entrapped loops of bowel, forming palpable masses. Abdominal masses were located at the root of the mesentery, the ileocecocolic junction, or the pelvic inlet. In 1 case, culture, serotyping, and polymerase chain reaction (PCR) analysis of the bacterial isolate identified K. pneumoniae expressing the hypermucoviscosity phenotype and capsular serotype K2 and determined that the K. pneumonia was genetically rmpA(+)/magA(-).

Laparoscopic antecolic Roux-en-Y gastric bypass with closure of internal defects leads to fewer internal hernias than the retrocolic approach.

BACKGROUND: Laparoscopic Roux-en-Y gastric bypass surgery reportedly has a higher rate of postoperative internal hernias than open bypass surgery. Even with closure of mesenteric defects, hernias occur in up to 9% of cases. To minimize this complication, an antecolic antegastric approach to anastomosis of the Roux limb and gastric pouch has been used. Whereas the retrocolic retrogastric technique creates three mesenteric defects, the antecolic approach produces only two: Petersen's defect and the jejunojejunostomy. The rate of internal hernias was compared among patients undergoing laparoscopic Roux-en-Y gastric bypass surgery using the retrocolic and antecolic approaches. METHODS: The experience of a single surgeon from August 2001 to September 2005 was reviewed. Only Roux-en-Y gastric bypass procedures were included. Patients were followed for a minimum of 18 months postoperatively. The retrocolic approach was used for 274 patients and the antecolic approach for 205 patients. All defects were closed at the time of surgery. With the antecolic approach, Petersen's defect was closed from the root of the mesentery of the Roux limb and the transverse colon mesentery up to the transverse colon. RESULTS: Of the 274 patients, 7 (2.6%) experienced a symptomatic internal hernia with the retrocolic retrogastric technique. No internal hernias were reported among the 205 patients treated with the antecolic antegastric method. Chi-square analysis showed that an antecolic approach was associated with a decreased rate of internal hernias (p < 0.025). Of 479 patients, 35 (7%) underwent diagnostic laparoscopy without any internal hernia found. Of these patients, 15 were found to have cholelithiasis and subjected to laparoscopic cholecystectomy. CONCLUSIONS: The antecolic antegastric approach to laparoscopic Roux-en-Y gastric bypass is associated with fewer postoperative hernias than the retrocolic retrogastric approach. The frequency of hernias using either technique is low if meticulous attention is paid to closure of all mesenteric defects.

Tunicamycin enhances neuroinvasion and encephalitis in mice infected with Venezuelan equine encephalitis virus.

Venezuelan equine encephalitis (VEE) viruses cause natural outbreaks in humans and horses and represent a significant biothreat agent. The effect of tunicamycin on the course of the disease in mice with VEE was investigated, and the combined effects of these agents was characterized. CD-1 mice given 2.5 microg of tunicamycin had >1,000-fold more virus in the brain 48 hours after infection with the virulent VEE strain V3000 and > or =100-fold of the attenuated strain V3034 at all tested times than did untreated mice, indicating enhanced neuroinvasion. Tunicamycin did not alter the viremia profiles of these viruses nor the replication of V3000 in the brain itself. Tunicamycin alone caused ultrastructural blood-brain barrier damage, yet neuroinvasion by V3000 in treated mice appeared to occur via the olfactory system rather than the blood-brain barrier. Tunicamycin-treated, V3000-infected mice also exhibited earlier and more severe weight loss, neurological signs, neuronal infection, neuronal necrosis and apoptosis, and inflammation than untreated, V3000-infected mice. The mean survival time of tunicamycin-treated, V3000-infected mice was 7.3 days versus 9.9 days for untreated, V3000-infected mice. These studies imply that animals that ingest toxins similar to tunicamycin, including the agent of annual ryegrass toxicity in livestock, are conceivably at greater risk from infections by encephalitis viruses and that humans and horses exposed to agents acting similar to tunicamycin may be more susceptible to encephalitis caused by VEE viruses. The exact mechanism of tunicamycin-enhanced neuroinvasion by VEE viruses requires further study.

Spontaneous pancreatic islet amyloidosis in 40 baboons.

Spontaneous amyloidosis occurs in many nonhuman primate species but remains difficult to diagnose and treat. Nonhuman primates continue to offer promise as animal models in which to study amyloidosis in humans. Amyloidosis was not diagnosed clinically but was found histologically in four male and 36 female baboons. The baboons averaged 18 years of age at death (range, 7-28 years). Clinical signs, if present, were hyperglycemia and cachexia. Blood glucose values were elevated in 12 of 30 baboons with available clinical pathology data. Four baboons had been clinically diagnosed as diabetic and three were treated with insulin. Amyloid was found in the islets of Langerhans of the pancreas in 40 baboons; 35 baboons had amyloid only in the islets of Langerhans. Amyloid was found in nonislet tissue of baboons as follows: five, nonislet pancreas; four, intestine and adrenal; three, kidney; two, prostate and spleen; and one each, lymph node, liver, gall bladder, stomach, tongue, urinary bladder, and salivary gland. Sections of paraffin-embedded tissues were evaluated for amyloid with hematoxylin and eosin (HE) and congo red (CR) staining, and using immunohistochemistry for human islet amyloid polypeptide (IAPP), calcitonin gene-related peptide (CGRP), glucagon, pancreatic polypeptide (PP), somatostatin (SS), and porcine insulin. Islet amyloid was positive with HE in 40 baboons, with CR in 39 baboons, and with IAPP and CGRP in 35 baboons. IAPP and CGRP only stained islet amyloid. PP, SS, glucagon, and porcine insulin did not stain amyloid. Islet amyloidosis in the baboon appears to be difficult to diagnose clinically, age-related, and similar to islet amyloidosis in other species. The baboon may be a good model for the study of islet amyloidosis in humans.

Fatal herpes simplex infection in a pygmy African hedgehog (Atelerix albiventris).

An adult pygmy African hedgehog developed acute posterior paresis attributed to a prolapsed intervertebral disc diagnosed by C-T scan. Corticosteroid therapy resulted in prompt resolution of the ataxia, but 2 weeks later the animal became anorexic and died. Macroscopically, the liver was stippled with punctate off-white foci which were confirmed microscopically to be foci of necrosis. Numerous hepatocytes contained intranuclear inclusions and syncytial cell formation was also present. A herpes virus was isolated and identified by fluorescent antibody and polymerase chain reaction studies as herpesvirus simplex type 1. To our knowledge, this is the first report of herpes infection in the African hedgehog and the first time herpes simplex has been identified as a cause of disease in insectivores.

Clinicopathologic features of viral agents of potential use by bioterrorists.

Concerns regarding the possible use of viral agents as weapons of mass destruction have heightened our need to recognize disease syndromes caused by these pathogens and to increase our understanding of potential countermeasures. This article reviews the clinical and pathologic features of various viruses that are generally thought to be potential biowarfare threats, and other related agents of topical interest. The epidemiologic and clinical aspects of recent natural outbreaks of disease caused by exotic viral agents are briefly described. Viral tissue targets, immune responses to these agents, relevant animal models, and diagnostic and potential therapeutic modalities also are discussed.

Cutaneous DNA vaccination against Ebola virus by particle bombardment: histopathology and alteration of CD3-positive dendritic epidermal cells.

We analyzed the localization of gold particles, expression of immunogenic protein, and histopathologic changes after vaccinating guinea pigs and mice with a DNA vaccine to the Ebola virus glycoprotein administered by cutaneous particle bombardment. Gold particles were deposited in all layers of the epidermis and in the dermis. Those in the epidermis were lost as the damaged layers sloughed, while those in the dermis were phagocytized by macrophages. Glycoprotein was demonstrated by immunohistochemistry primarily in keratinocytes in the epidermis and hair follicle epithelium and less frequently in dermal macrophages, fibroblasts, sebocytes, and cells that appeared to be Langerhans cells. The number of cells that expressed glycoprotein increased between 4 and 8 hours postvaccination, then decreased to near zero by 48 hours. The vaccine sites were histologically divisible into three zones. The central portion, zone 1, contained the most gold particles in the dermis and epidermis and had extensive tissue damage, including full-thickness epidermal necrosis. Zone 2 contained fewer gold particles in the epidermis and dermis and had less extensive necrosis. The majority of cells in which glycoprotein was expressed were in zone 2. Zone 3 contained gold particles only in the epidermis and had necrosis of only a few scattered cells. Regeneration of the epidermis in damaged areas was evident at 24 hours postvaccination and was essentially complete by day 5 in the mice and day 10 in the guinea pigs. Inflammatory changes were characterized by hemorrhage, edema, and infiltrates of neutrophils initially and by infiltrates of lymphocytes and macrophages at later times. In zone 1, inflammation affected both the epidermis and dermis. Peripherally, inflammation was relatively limited to the epidermis. CD3-positive dendritic epidermal cells were demonstrated in the epidermis and superficial hair follicles of unvaccinated immunocompetent mice and beige mice but not of SCID mice. These cells disappeared from all but the most peripheral portions of the vaccine sites of vaccinated mice within 24 hours. They reappeared slowly, failing to reach numbers comparable with unvaccinated mice by 35 days postvaccination. The epidermis of control guinea pigs also had CD3-positive cells, but they did not have dendrites. These findings should contribute to a better understanding of the mechanisms operating in response to DNA vaccination by particle bombardment.

Pathogenesis of experimental Ebola Zaire virus infection in BALB/c mice.

Guinea-pigs and non-human primates have traditionally been used as animal models for studying Ebola Zaire virus (EBO-Z) infections. The virus was also recently adapted to the stage of lethal virulence in BALB/c mice. This murine model is now in use for testing antiviral medications and vaccines. However, the pathological features of EBO-Z infection in mice have not yet been fully described. To identify sites of viral replication and characterize sequential morphological changes in BALB/c mice, adult female mice were infected with mouse-adapted EBO-Z and killed in groups each day for 5 days post-infection. Tissues were examined by light microscopy, immunohistochemistry, electron microscopy and in-situ hybridization. As in guinea-pigs and non-human primates, cells of the mononuclear phagocytic system were the earliest targets of infection. Viral replication was observed by day 2 in macrophages in lymph nodes and spleen. By the time of onset of illness and weight loss (day 3), the infection had spread to hepatocytes and adrenal cortical cells, and to macrophages and fibroblast-like cells in many organs. Severe lymphocytolysis was observed in the spleen, lymph nodes and thymus. There was minimal infection of endothelial cells. All of these changes resembled those observed in EBO-Z-infected guinea-pigs and non-human primates. In contrast to the other animal models, however, there was little fibrin deposition in the late stage of disease. The availability of immunodeficient, "gene-knockout" and transgenic mice will make the mouse model particularly useful for studying the early steps of Ebola pathogenesis.

Spontaneous amyloidosis in twelve chimpanzees, Pan troglodytes.

Spontaneous amyloidosis was diagnosed in 11 male and 1 female chimpanzees and confirmed histologically and immunohistochemically. The chimpanzees were > or = 15 years of age when first diagnosed and averaged 22.4 years of age. The average survival time after diagnosis of systemic amyloidosis was 1.86 years with a standard deviation of 4.06 years (n = 7). The chimpanzees with amyloidosis were asymptomatic except for hepatomegaly, which became more detectable with age. Significant increases in clinical chemistry values, as compared with referenced normals and established normals, of blood urea nitrogen (BUN), asparate aminotransferase (AST), gamma-glutamyltransferase (GGT), globulin, total protein, creatinine phosphokinase (CPK), sedimentation rate, and triglycerides were found in animals 7 years of age or older with amyloidosis. These serum chemistry values, while increased in chimpanzees with amyloidosis, were generally within normal limits. Immunohistochemistry for both amyloid A protein and amyloid P component-labeled extracellular amyloid in all chimpanzees with amyloidosis was determined. Amyloid was deposited primarily in the liver. Amyloidosis in the chimpanzee is a chronic, intractable, progressive, fatal disease, and appears to be similar to secondary amy loidosis in other species.

Fatal lymphoproliferative disease associated with a novel gammaherpesvirus in a captive population of common marmosets.

BACKGROUND AND PURPOSE: Callitrichids (marmosets and tamarins) are extremely susceptible to experimental tumor induction by herpesviruses native to other primate species. A colony of common marmosets developed a syndrome of weight loss, inappetence, diarrhea, and in several animals, palpable abdominal masses. METHODS: Marmosets in the colony were subjected to histologic examination and serologic testing for Epstein-Barr virus (EBV). The DNA from tumors that developed in the marmosets was subjected to consensus primer polymerase chain reaction (PCR) analysis designed to amplify conserved regions of herpesvirus genomes. RESULTS: The mesenteric lymph nodes and intestinal mucosa were consistently infiltrated by principally B lymphocytes, which often obliterated the normal architecture. Of 84 clinically normal marmosets, 52 were seropositive for EBV. The tumor DNA contained previously unreported herpesvirus sequences closely related to but distinct from those of EBV, Herpesvirus papio, and these lymphocryptovirus, a novel gammaherpesvirus. Results of PCR analysis of circulating lymphocytes from EBV-positive, clinically normal marmosets were negative for EBV antibodies and were positive for marmoset lymphocryptovirus; PCR analysis of circulating lymphocytes from EBV-negative marmosets yielded negative results for EBV and this novel marmoset lymphocryptovirus. CONCLUSION: This novel gammaherpesvirus possibly associated with tumor development may have important management implications for captive callitrichids.

Pathology of fatal West Nile virus infections in native and exotic birds during the 1999 outbreak in New York City, New York.

West Nile fever caused fatal disease in humans, horses, and birds in the northeastern United States during 1999. We studied birds from two wildlife facilities in New York City, New York, that died or were euthanatized and were suspected to have West Nile virus infections. Using standard histologic and ultrastructural methods, virus isolation, immunohistochemistry, in situ hybridization and reverse-transcriptase polymerase chain reaction, we identified West Nile virus as the cause of clinical disease, severe pathologic changes, and death in 27 birds representing eight orders and 14 species. Virus was detected in 23/26 brains (88%), 24/ 25 hearts (96%), 15/18 spleens (83%), 14/20 livers (70%), 20/20 kidneys (100%), 10/13 adrenals (77%), 13/ 14 intestines (93%), 10/12 pancreata (83%), 5/12 lungs (42%), and 4/8 ovaries (50%) by one or more methods. Cellular targets included neurons and glial cells in the brain, spinal cord, and peripheral ganglia; myocardial fibers; macrophages and blood monocytes; renal tubular epithelium; adrenal cortical cells; pancreatic acinar cells and islet cells; intestinal crypt epithelium; oocytes; and fibroblasts and smooth muscle cells. Purkinje cells were especially targeted, except in crows and magpies. Gross hemorrhage of the brain, splenomegaly, meningoencephalitis, and myocarditis were the most prominent lesions. Immunohistochemistry was an efficient and reliable method for identifying infected cases, but the polyclonal antibody cross-reacted with St. Louis encephalitis virus and other flaviviruses. In contrast, the in situ hybridization probe pWNV-E (WN-USAMRIID99) reacted only with West Nile virus. These methods should aid diagnosticians faced with the emergence of West Nile virus in the United States.

Apoptosis induced in vitro and in vivo during infection by Ebola and Marburg viruses.

Induction of apoptosis has been documented during infection with a number of different viruses. In this study, we used transmission electron microscopy (TEM) and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling to investigate the effects of Ebola and Marburg viruses on apoptosis of different cell populations during in vitro and in vivo infections. Tissues from 18 filovirus-infected nonhuman primates killed in extremis were evaluated. Apoptotic lymphocytes were seen in all tissues examined. Filoviral replication occurred in cells of the mononuclear phagocyte system and other well-documented cellular targets by TEM and immunohistochemistry, but there was no evidence of replication in lymphocytes. With the exception of intracytoplasmic viral inclusions, filovirus-infected cells were morphologically normal or necrotic, but did not exhibit ultrastructural changes characteristic of apoptosis. In lymph nodes, filoviral antigen was co-localized with apoptotic lymphocytes. Examination of cell populations in lymph nodes showed increased numbers of macrophages and concomitant depletion of CD8+ T cells and plasma cells in filovirus-infected animals. This depletion was particularly striking in animals infected with the Zaire subtype of Ebola virus. In addition, apoptosis was demonstrated in vitro in lymphocytes of filovirus-infected human peripheral blood mononuclear cells by TEM. These findings suggest that lymphopenia and lymphoid depletion associated with filoviral infections result from lymphocyte apoptosis induced by a number of factors that may include release of various chemical mediators from filovirus-infected or activated cells, damage to the fibroblastic reticular cell conduit system, and possibly stimulation by a viral protein.