Adult zebrafish intestine resection: a novel model of short bowel syndrome, adaptation, and intestinal stem cell regeneration.

Loss of significant intestinal length from congenital anomaly or disease may lead to short bowel syndrome (SBS); intestinal failure may be partially offset by a gain in epithelial surface area, termed adaptation. Current in vivo models of SBS are costly and technically challenging. Operative times and survival rates have slowed extension to transgenic models. We created a new reproducible in vivo model of SBS in zebrafish, a tractable vertebrate model, to facilitate investigation of the mechanisms of intestinal adaptation. Proximal intestinal diversion at segment 1 (S1, equivalent to jejunum) was performed in adult male zebrafish. SBS fish emptied distal intestinal contents via stoma as in the human disease. After 2 wk, S1 was dilated compared with controls and villus ridges had increased complexity, contributing to greater villus epithelial perimeter. The number of intervillus pockets, the intestinal stem cell zone of the zebrafish increased and contained a higher number of bromodeoxyuridine (BrdU)-labeled cells after 2 wk of SBS. Egf receptor and a subset of its ligands, also drivers of adaptation, were upregulated in SBS fish. Igf has been reported as a driver of intestinal adaptation in other animal models, and SBS fish exposed to a pharmacological inhibitor of the Igf receptor failed to demonstrate signs of intestinal adaptation, such as increased inner epithelial perimeter and BrdU incorporation. We describe a technically feasible model of human SBS in the zebrafish, a faster and less expensive tool to investigate intestinal stem cell plasticity as well as the mechanisms that drive intestinal adaptation.

Durability of sustained response shown in paediatric patients with chronic hepatitis C who were treated with interferon alfa-2b plus ribavirin.

Long-term studies in adults indicate that sustained virologic response (SVR) after combination treatment for chronic hepatitis C (CHC) predicts long-term clearance. Although peginterferon plus ribavirin is now standard care for children with CHC, long-term follow-up studies are not yet available. This study evaluated durability of virologic response over 5 years in children previously treated with interferon alfa-2b plus ribavirin (IFN/R). Ninety-seven of 147 children with CHC, who were treated with IFN/R and completed the 6-month follow-up in two previous clinical trials, participated in this long-term follow-up study. All were assessed annually for up to 5 years; patients with SVR were assessed for durability of virologic response. Children with SVR (n = 56) and those with detectable hepatitis C virus (HCV) RNA 24-week post-treatment (n = 41) were followed for a median of 284 weeks. Overall, 70% (68/97) of patients completed the 5-year follow-up. One patient with genotype 1a CHC had SVR and relapsed at year 1 of follow-up with the same genotype. Kaplan-Meier estimate for sustained response at 5 years was 98% (95% CI: 95%, 100%). Six patients with low-positive HCV RNA levels (n = 4) or missing HCV RNA at the 24-week follow-up visit (n = 2) in the initial treatment studies had virologic response during this long-term follow-up study. Linear growth rate was impaired during treatment with rapid increases in the immediate 6 months post-treatment. Mean height percentile at the end of the 5-year follow-up was slightly less than the mean pretreatment height percentile. Five patients experienced serious adverse events; none related to study drug exposure. SVR after IFN/R predicts long-term clearance of HCV in paediatric patients; growth normalized in the majority of children during the long-term follow-up. Similar long-term results could be expected after peginterferon alfa-2b plus ribavirin treatment.

Gravitational mechanism for sea-floor spreading.

The gravitational attraction of the continents produces a force field at the surface of the earth, similar in geometry to lithospheric displacements deduced from studies of earthquake focal mechanisms.

Digital model of evaporite sedimentation.

A deterministic digital model to simulate evaporite sedimentation permits experimentation with depth of water, shape of salt basin, number, position, and strength of the inlets, and rate of evaporation. It provides a reasonable fit to salt thickness and distribution in the Upper Silurian Salina Formation of Michigan.

Chemokine IP-10: an adjunct marker for latent tuberculosis infection in children.

SETTING: Recent reports indicate a role of chemokine inducible protein 10 (IP-10) in Mycobacterium tuberculosis infection substantiated by the detection of elevated levels in plasma and at infection foci in individuals infected with M. tuberculosis. OBJECTIVE: To evaluate IP-10 as a potential marker for the diagnosis of M. tuberculosis infection in children living in a region of low tuberculosis (TB) prevalence. DESIGN: IP-10 levels were obtained after whole blood stimulation with M. tuberculosis-specific antigens in 127 children. IP-10 results were evaluated upon gradations of exposure risk to M. tuberculosis and correlation with tuberculin skin test and an interferon-gamma release assay (IGRA). RESULTS: IP-10 reactivity correlated well to risk of exposure to M. tuberculosis in children. There was a strong correlation between IP-10 and IGRA results. IP-10 responses, unlike interferon-gamma (IFN-gamma), were not age-dependent and detected more positive results in children aged <5 years. In the children with active disease, the IGRA was more sensitive than IP-10 at detecting M. tuberculosis infection. CONCLUSION: Our findings suggest that IP-10 in combination with IFN-gamma may enhance the diagnostic performance of IGRAs in detecting M. tuberculosis infection, especially in young children.

Applications of PET imaging with the proliferation marker [18F]-FLT.

[18F]-3'-fluoro-3'-deoxythymidine (FLT) is a nucleoside-analog imaging agent for quantifying cellular proliferation that was first reported in 1998. It accumulates during the S-phase of the cell cycle through the action of cytosolic thymidine kinase, TK1. Since TK1 is primarily expressed in dividing cells, FLT uptake is essentially limited to dividing cells. Thus FLT is an effective measure of cell proliferation. FLT uptake has been shown to correlate with the more classic proliferation marker, the monoclonal antibody to Ki-67. Increased cellular proliferation is known to correlate with worse outcome in many cancers. However, the Ki-67 binding assay is performed on a sampled preparation, ex vivo, whereas FLT can be quantitatively measured in vivo using positron emission tomography (PET). FLT is an effective and quantitative marker of cell proliferation, and therefore a useful prognostic predictor in the setting of neoplastic disease. This review summarizes clinical studies from 2011 forward that used FLT-PET to assess tumor response to therapy. The paper focuses on our recommendations for a standardized clinical trial protocol and components of a report so multi center studies can be effectively conducted, and different studies can be compared. For example, since FLT is glucuronidated by the liver, and the metabolite is not transported into the cell, the plasma fraction of FLT can be significantly changed by treatment with particular drugs that deplete this enzyme, including some chemotherapy agents and pain medications. Therefore, the plasma level of metabolites should be measured to assure FLT uptake kinetics can be accurately calculated. This is important because the flux constant (KFLT) is a more accurate measure of proliferation and, by inference, a better discriminator of tumor recurrence than standardized uptake value (SUVFLT). This will allow FLT imaging to be a specific and clinically relevant prognostic predictor in the treatment of neoplastic disease.

Immunologic and virologic responses to HAART in severely immunocompromised HIV-1-infected children.

OBJECTIVE: To determine the long-term immunologic and virologic effects of highly active antiretroviral therapy (HAART) in children with AIDS. DESIGN: A prospective observational study. SETTING: Two pediatric HIV clinics. PARTICIPANTS: Twenty-five protease-inhibitor naive HIV-infected children (aged 2-18 years) with advanced disease (CD4 < or =6%). INTERVENTION: HAART (one protease inhibitor and one or more nucleoside analogs). Diphtheria and tetanus immunization in six patients after 18 months of therapy. MAIN OUTCOME MEASURES: Changes in percentage of CD4 cells and plasma HIV-1 RNA levels; post-treatment assays of lymphoproliferative responses to recall antigens; CD4 cell memory phenotype. RESULTS: Median duration of follow-up was 18.8 months (range, 7.5-28 months). At baseline the CD4 cell percentage was 2% (range, 0-6%), this increased significantly to 16% (range, 3-48%) above baseline at 12 months (P = 0.002). The mean maximum CD4 cell increase was 20.7% (range 4-48%) which corresponds to 657x10(6) cells/l (range, 30-2240x10(6) cells/l) above baseline. By contrast, the median viral load was not significantly lower at 12 months than at baseline (P = 0.34), and only 25% of the patients had sustained undetectable viral load. Of the reconstituted CD4 cells 70% were naive, and none of the subjects had lymphoproliferative responses to tetanus and diphtheria although 40% did develop responses to Candida, an environmental antigen. A single immunization with diphtheria and tetanus toxoid produced lymphoproliferative responses to tetanus in three out of six patients. CONCLUSIONS: HAART was associated with sustained increases in CD4 cell counts, despite a high incidence of 'virologic failure'. CD4 counts and the proportion of naive cells were higher than have been reported in adults, which may be a reflection of greater thymic activity in children. Memory cell clones for antigens encountered in the past which are not prevalent before therapy could not be expanded without additional antigenic exposure.

Lack of correlation between maternal antibodies to V3 loop peptides of gp120 and perinatal HIV-1 transmission. The NYC Perinatal HIV Transmission Collaborative Study.

Recent reports have suggested that maternal antibodies to specific epitopes of the variable region 3 (V3 loop) of gp120 of HIV-1 might protect against perinatal transmission. In an attempt to confirm these findings, sera from 34 HIV-1-seropositive mothers, representing 13 episodes of mother-to-infant transmission and 23 episodes of non-transmission (two mothers had two pregnancies each during the study period), were tested for the presence of antibodies to various regions of the gp120 V3 loop. Synthetic peptides were generated from HIV-1MN. Of the four peptides tested by enzyme-linked immunosorbent assay (ELISA), only antibody to the C53 peptide (Env310-322, principal neutralizing determinant) was present in maternal sera. Antibody to the C53 sequence was present in 11 specimens from transmitting mothers and 21 from non-transmitting mothers (84.6 and 91.3%, respectively, P = 0.6). No reactivity was detected against the C51, C57, or C58 peptide sequences, located on the sides of the V3 loop. In an antigen-limited ELISA, only two specimens from transmitting mothers and two specimens from non-transmitting mothers had detectable 'high-affinity' antibodies to C53 at low antigen concentrations (15.4 and 8.7%, respectively; P = 0.6). Our results do not support previous reports that epitope-specific antibodies to the V3 loop peptides protect against perinatal transmission. Further research is required to determine whether any specific maternal humoral response might influence HIV-1 perinatal transmission.

CD8+ T-cell-mediated suppression of HIV replication in the first year of life: association with lower viral load and favorable early survival.

OBJECTIVE AND DESIGN: To study the role and development of non-cytotoxic CD8+ T-cell-mediated suppression of HIV replication in early perinatal HIV infection in a prospective study of vertically infected infants. CD8 T-cell-mediated HIV suppression was measured several times during the first year of life and correlated with viral load, cytotoxic T-cell (CTL) activity, in vitro antibody production (IVAP) and clinical outcome. METHODS: CD8+ T-cell-mediated HIV suppression was measured by comparing the amount of p24 antigen produced by endogenously infected lymphocytes with cultures of the same number of autologous CD4+ T cells from which CD8+ cells were removed immunomagnetically. CD8 viral suppressive activity (VSA) was defined as a > or = 50% reduction in p24 antigen in the cultures containing CD8+ cells. RESULTS: CD8+ T-cell-mediated HIV VSA was detected in 11/16 infants in the first year of life, including six/nine infants studied before 6 months and as early as 3 weeks of age. Infants who demonstrated CD8 VSA had a lower early peak and 6-month 'setpoint' plasma HIV RNA concentration than infants who lacked CD8 VSA [1.51 versus 4.94 and 0.094 versus 0.639 x 10(6) copies/ml, respectively, and higher CD4 percentage at 1 year of age. Survival of infants lacking CD8 VSA (four/six were rapid progressors) was shorter than for infants who demonstrated CD8 VSA (none out of 10 were rapid progressors). CD8 VSA was present before CTL and before or at the same time as IVAP in two of two and 11 of 14 infants studied, respectively. CONCLUSIONS: CD8+ T-cell-mediated VSA can be demonstrated in a large proportion of HIV-infected infants early in the course of infection. This non-cytolytic HIV-suppressive immune response appears to play an important protective role in the early control of perinatal HIV infection at a time when other immune responses are either absent or deficient.

A novel detection assay for the early diagnosis of HIV-1 infected infants.

This investigation compares the results of a new method of diagnosing HIV-1 infection in infants < 6 months of age with currently employed techniques including cocultivation, the polymerase chain reaction (PCR), serum p24 antigen, and in vitro antibody production (IVAP) measurements. The new method, called in vitro antigen (IVAG), measures p24 antigen released into culture supernatants of peripheral blood mononuclear cells that are incubated with Epstein-Barr virus (EBV). No activated donor lymphocytes or interleukin 2 (IL-2) are added to the culture. Using this technique, HIV-1 infection was detected in 15 of 17 HIV-1-infected infants < 2 months of age, including 3 of 7 infants tested at birth, and 15 of 15 HIV-1-infected infants between 2 and 6 months of age. None of 83 determinations of 15 uninfected infants were positive. These results were found to be comparable to results obtained by the traditional cocultivation technique and the polymerase chain reaction. Because of its simplicity and reduced cost, this sensitive and specific assay could be a valuable addition to the current methods of diagnosis of HIV-1 infection in young infants.

Thrombocytopenia in children infected with human immunodeficiency virus: long-term follow-up and therapeutic considerations.

Among 180 children infected with human immunodeficiency virus (HIV-1), 14 (8%) developed thrombocytopenia during the course of the disease and have been followed for an average period of 18.8 months. Eight of 14 patients had clinical signs of bleeding. Increased levels of anti-platelet IgG antibodies were detected in 86% of patients tested and did not correlate with severity of disease. Eight patients were treated initially with intravenous immunoglobulins (IVIG) and responded with a transient increase in the platelet count of at least 30 x 10(9)/L. Sustained remission could not be achieved in the patients treated with IVIG alone. Corticosteroids were used in 6 patients who became refractory to IVIG and resulted in sustained remission in only one patient. Spontaneous remission of thrombocytopenia occurred in one patient. Ten patients were treated with zidovudine (ZVD) for a period of 3-20 months. Sustained improvement in the platelet counts occurred in only three of the children treated with ZVD.

Localization and protection of kidneys in radiation treatment planning using computed tomography.

Irradiation treatment portals of the upper abdomen must limit the dose to the kidneys. Sparing one-third of the parenchyma of each kidney will prevent late clinical sequelae. One hundred CT scans of the abdomen were studied to evaluate using the vertebrae as landmark for treatment planning. In lateral fields, using the anterior border of the vertebral column as a landmark for the posterior high isodose line will limit treatment to less than 60% (mean 22%) of a single kidney. Placing the edge of an anterior/posterior field 2 cm lateral to the vertebral column will limit the dose to less than 44% of a single kidney (mean 11%).

Ultrasonography: an aid in the diagnosis of masses in pediatric patients.

Ultrasound was used to evaluate 100 pediatric patients suspected of having a mass. This technique was found to be useful in several ways: (1) differentiation of cystic, solid, and complex masses, which is not usually possible with routine roentgenographic evaluation; (2) delineation of free fluid collections from those that are loculated or contained within masses; (3) measurement of the size of both normal and abnormal structures; and (4) confirmation of the abnormal position or absence of organs. Ultrasound was used as a supplement to routine clinical and radiologic studies.

Delayed recognition of human immunodeficiency virus infection in preadolescent children.

Thirty-two (18%) of 181 children cared for at our institution who were infected with the human immunodeficiency virus type 1 (HIV-1) were first seen, and HIV was diagnosed, when they were 4 years of age and older. Initial complaints or diagnoses for these children included the following: hematologic disorders (5) (3 idiopathic thrombocytopenic purpura, 1 neutropenia, 1 anemia); recurrent bacterial infections (10); Pneumocystis carinii pneumonia (3); developmental delay (1); skin disorders (2) (1 genital wart, 1 chronic zoster); weight loss (3); malignancy (1); and nephropathy (1). Eight children were referred for evaluation because of maternal HIV-1 infection. The risk factors for HIV-1 infection included maternal/perinatal exposure (22), perinatal blood transfusion (6), blood transfusion during infancy (2), and sexual abuse (2). Ten (31%) of the 32 children have subsequently died. The longest survival from perinatal infection was 12 years. HIV-1 infection in children can result in a prolonged clinical latency and can masquerade as other pathologic conditions. The absence of clinical symptoms in older children at risk for HIV-1 infection should not deter HIV testing.

Early changes in quasispecies repertoire in HIV-infected infants: correlation with disease progression.

The evolution of HIV-1 quasispecies in patients during the first year of life was investigated in 10 vertically infected infants, using heteroduplex analysis of the V3-V5 region of env. Four subjects, who showed little viral evolution during the period of the study, had rapid progression of disease and early loss of CD4(+) cells. The remaining six subjects, who were slow progressors, evolved new viral variants within 6 months, and in one case by 1 month of age. Of the four patients who were PCR positive at birth, one was infected with multiple HIV-1 variants. These results show that in HIV-infected children, multiple variants may initiate infection and early quasispecies diversification is associated with a favorable clinical outcome.

Expression patterns of the HIV type 1 coreceptors CCR5 and CXCR4 on CD4+ T cells and monocytes from cord and adult blood.

We have measured the surface expression of the HIV-1 coreceptors CCR5 and CXCR4 on CD4+ T cells and monocytes from cord and adult blood. The expression of CCR5 was largely restricted to the memory (CD45RAlow) subset, whereas CXCR4 was expressed on both memory and naive (CD45RAhigh) T cells. The paucity of memory CD4+ T cells in cord blood means that CCR5-positive cells are relatively uncommon, so the overall extent of CCR5 expression was reduced in cord blood, compared with adult blood. IL-2 activation of CD4+ T cells from both cord and adult bloods caused a substantial increase in CCR5 expression, but moderately decreased CXCR4 expression. PHA stimulation increased CCR5 expression slightly, but only on naive cells. Monocytes expressed both CCR5 and CXCR4 at levels that differed little between cord and adult blood.

Disseminated fungal infections in children infected with human immunodeficiency virus.

A retrospective review of charts of 156 human immunodeficiency virus-infected children cared for during a 7.5-year period revealed 11 episodes of disseminateed candidiasis (DC) occurring in 11 patients (7%). All 11 patients developed the fungal infection in the context of advanced human immunodeficiency virus infection. All but one were hospital-acquired, occurring at a mean of 2.3 months after admission. Ten patients had been febrile for more than 14 days before diagnosis. Previous oral thrush and central venous catheters (73 and 82% of patients) represented major predisposing factors for development of DC. Neutropenia (2 of 11 patients) did not represent a major risk factor for DC. Candida albicans was isolated in 9 patients, Rhodotorula minuta in 1 patient and 1 fungal isolate could not be identified. Sources of isolation were blood (8 of 11 patients), central venous catheters (3 of 11) and urine (2 of 11). Lungs (6 of 11 patients), esophagus (5 of 11) and brain, heart and kidneys (3 patients each) were the organs most often involved in DC. Antemortem diagnosis was achieved in only 7 (64%) patients; none of the 4 patients with DC diagnosed postmortem had been treated before death. Seven patients were treated with amphotericin B; 6 of them died but only 3 were treated for more than 7 days of therapy. The overall mortality was 90% (10 of 11 patients). In all 20% of the 50 human immunodeficiency virus-infected children who died at our hospital during the study period had an episode of DC in close proximity to their death. DC was considered the direct cause of death in 4 of 10 children.

Streptococcus pneumoniae in human immunodeficiency virus type 1-infected children.

The purpose of this study was to characterize systemic Streptococcus pneumoniae disease in human immunodeficiency virus type 1 (HIV-1)-infected children. All cases of bacteremia and meningitis caused by S. pneumoniae among children less than 18 years old were collected by review of the Microbiology Laboratory records at the Bellevue Hospital Center during the period August 1, 1978, through July 31, 1993. There were 31 bouts of systemic S. pneumoniae disease in 19 of 235 HIV-1-infected children cared for by the Pediatric Infectious Disease staff and 116 bouts in 113 children not known to be HIV-1-infected. Four of the 19 HIV-1-infected children had multiple episodes of S. pneumoniae bacteremia as compared with 3 of 113 in the general population (P = 0.008). The frequency of serotypes and distribution of infections by season of the year did not differ between the 2 groups. The median ages at the time of the S. pneumoniae infection were 1.8 and 1.1 years for the HIV-1-infected children and the general population of children, respectively, when those children with multiple episodes were included for their initial episode only (P = 0.06). In the HIV-1-infected patients, 10 episodes were associated with pneumonia, 5 with pneumonia and otitis media, 5 with otitis media only, 1 with pneumonia and meningitis, 1 with meningitis only and 1 with periorbital cellulitis; 5 had no apparent focus of infection. One episode of pneumonia was complicated by lung abscess and there were 2 deaths. Most HIV-1-infected patients recovered without significant sequelae, and the clinical course of their systemic infections did not appear to be markedly different than that of healthy children.

Sequential changes in the CT numbers of the normal canine kidney following intravenous contrast administration. I. The renal cortex.

Using a 30-second computed tomography (CT) scanner, the sequential changes in CT numbers of the kidney were determined in three healthy dogs after intravenous administration of sodium and meglumine diatrizoate and iothalamate. For all contrast media, the mean CT number of the cortex was greatest within 2 minutes of rapid intravenous administration. At doses comparable to those used clinically, a linear relationship was demonstrated between the amount of iodine administered (in mg/kg body weight) and the corrected peak mean CT number of the cortex, such that doubling the amount of iodine caused the corrected peak mean CT number of the cortex to approximately double. Following the peak, the mean CT number of the cortex gradually declined. For all contrast media, the corrected mean CT number to corrected peak mean CT number ratios at 5, 10 and 20 minutes were 58 +/- 3%, 39 +/- 3%, and 28 +/- 5% respectively. Our data suggest that rapid-sequence CT may be a valuable tool for evaluating the physiology of renal contrast media excretion.

Sequential changes in the CT numbers of the normal canine kidney following intravenous contrast administration. II: The renal medulla.

Following the intravenous administration of sodium and meglumine salts of both diatrizoate and iothalamate (at doses of 310-880 mg I/kg body weight) sequential changes in computed tomographic (CT) numbers of the inner medulla were determined in three dogs, using a 30-second CT scanner. Peak medullary enhancement was greater than, and usually occurred 1-2 minutes after, peak cortical enhancement. The CT number of the medulla increased linearly with increasingly large doses of the contrast agent. At peak enhancement, the meglumine salts produced a significantly lower (p less than 0.025) mean CT attenuation value of the medulla than did the sodium salts. The difference in mean attenuation values between the sodium salts and meglumine salts was maximum (50-60 HU)at peak enhancement. Our data indicate the known difference in renal handling of the meglumine and sodium salts is readily detectable by CT.