Monte Carlo simulations and phantom validation of low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope

PURPOSE

To use MC simulations and phantom measurements to investigate the dosimetry of a kilovoltage x-ray beam from an IR fluoroscope to deliver low-dose (0.3-1.0 Gy) radiotherapy to the lungs.

MATERIALS AND METHODS

PENELOPE was used to model a 125 kV, 5.94 mm Al HVL x-ray beam produced by a fluoroscope. The model was validated through depth-dose, in-plane/cross-plane profiles and absorbed dose at 2.5-, 5.1-, 10.2- and 15.2-cm depths against the measured beam in an acrylic phantom. CT images of an anthropomorphic phantom thorax/lungs were used to simulate 0.5 Gy dose distributions for PA, AP/PA, 3-field and 4-field treatments. DVHs were generated to assess the dose to the lungs and nearby organs. Gafchromic film was used to measure doses in the phantom exposed to PA and 4-field treatments, and compared to the MC simulations.

RESULTS

Depth-dose and profile results were within 3.2% and 7.8% of the MC data uncertainty, respectively, while dose gamma analysis ranged from 0.7 to 1.0. Mean dose to the lungs were 1.1-, 0.8-, 0.9-, and 0.8- Gy for the PA, AP/PA, 3-field, and 4-field after isodose normalization to cover ∼ 95% of each lung volume. Skin dose toxicity was highest for the PA and lowest for the 4-field, and both arrangements successfully delivered the treatment on the phantom. However, the dose distribution for the PA was highly non-uniform and produced skin doses up to 4 Gy. The dose distribution for the 4-field produced a uniform 0.6 Gy dose throughout the lungs, with a maximum dose of 0.73 Gy. The average percent difference between experimental and Monte Carlo values were -0.1% (range -3% to +4%) for the PA treatment and 0.3% (range -10.3% to +15.2%) for the 4-field treatment.

CONCLUSION

A 125 kV x-ray beam from an IR fluoroscope delivered through two or more fields can deliver an effective low-dose radiotherapy treatment to the lungs. The 4-field arrangement not only provides an effective treatment, but also significant dose sparing to healthy organs, including skin, compared to the PA treatment. Use of fluoroscopy appears to be a viable alternative to megavoltage radiation therapy equipment for delivering low-dose radiotherapy to the lungs.

Pericytes: Intrinsic Transportation Engineers of the CNS Microcirculation

Pericytes in the brain are candidate regulators of microcirculatory blood flow because they are strategically positioned along the microvasculature, contain contractile proteins, respond rapidly to neuronal activation, and synchronize microvascular dynamics and neurovascular coupling within the capillary network. Analyses of mice with defects in pericyte generation demonstrate that pericytes are necessary for the formation of the blood-brain barrier, development of the glymphatic system, immune homeostasis, and white matter function. The development, identity, specialization, and progeny of different subtypes of pericytes, however, remain unclear. Pericytes perform brain-wide 'transportation engineering' functions in the capillary network, instructing, integrating, and coordinating signals within the cellular communicome in the neurovascular unit to efficiently distribute oxygen and nutrients ('goods and services') throughout the microvasculature ('transportation grid'). In this review, we identify emerging challenges in pericyte biology and shed light on potential pericyte-targeted therapeutic strategies.

Digital solutions for mental health care during the COVID-19 pandemic: A systematic qualitative review and swot analysis

Introduction

Since its early stages, the Covid-19 outbreak has posed immense challenges for effective, scalable and rapid interventions. Telehealth approaches have been considered as key part of an effective pandemic response.

Objectives

The aim of this systematic review was to evaluate the role of digital solutions in fighting the mental health needs during COVID-19 outbreak.

Methods

This review was conducted through searching four databases including PubMed, Scopus, Web of Science, and Science Direct. Inclusion criteria included studies clearly defining any use of telehealth services in all aspects of mental health care during COVID-19 outbreak, published from December 31, 2019 to October 31, 2020, written in English language and published in peer-reviewed journals. Narrative synthesis was undertaken to summarize the findings according a SWOT (strengths, weaknesses, opportunities, threats) analysis.

Results

62 studies met the inclusion out of the 278 search results. Data converged on: strengths in minimizing the risk of Covid-19 transmission, reduction of travel time and costs, comparable effectiveness to in-person care; weaknesses i.e. decreased ability to detect non-verbal cues, lower therapeutic alliance, possible technical connection problems; opportunities in improving the healthcare system and expanding its accessibility for patients also for the future; threats such as privacy and legal issues, and risk to overlook vulnerable populations (e.g. elderly, marginalized ethnic minorities).

Conclusions

In the midst of a global mental health emergency, telehealth may represent a “virtually perfect” solution. However, further implementations facing issues of quality, justice and healthcare equity are required to ensure that all patients receive the care they need.

Graft-versus-host disease after double-unit cord blood transplantation has unique features and an association with engrafting unit-to-recipient HLA match

Manifestations of and risk factors for graft-versus-host disease (GVHD) after double-unit cord blood transplantation (DCBT) are not firmly established. We evaluated 115 DCBT recipients (median age, 37 years) who underwent transplantation for hematologic malignancies with myeloablative or nonmyeloablative conditioning and calcineurin inhibitor/mycophenolate mofetil immunosuppression. Incidence of day 180 grades II to IV and III to IV acute GVHD (aGVHD) were 53% (95% confidence interval, 44 to 62) and 23% (95% confidence interval, 15 to 31), respectively, with a median onset of 40 days (range, 14 to 169). Eighty percent of patients with grades II to IV aGVHD had gut involvement, and 79% and 85% had day 28 treatment responses to systemic corticosteroids or budesonide, respectively. Of 89 engrafted patients cancer-free at day 100, 54% subsequently had active GVHD, with 79% of those affected having persistent or recurrent aGVHD or overlap syndrome. Late GVHD in the form of classic chronic GVHD was uncommon. Notably, grades III to IV aGVHD incidence was lower if the engrafting unit human leukocyte antigen (HLA)-A, -B, -DRB1 allele match was >4/6 to the recipient (hazard ratio, 0.385; P = .031), whereas engrafting unit infused nucleated cell dose and unit-to-unit HLA match were not significant. GVHD after DCBT was common in our study, predominantly affected the gut, and had a high therapy response, and late GVHD frequently had acute features. Our findings support the consideration of HLA- A,-B,-DRB1 allele donor-recipient (but not unit-unit) HLA match in unit selection, a practice change in the field. Moreover, new prophylaxis strategies that target the gastrointestinal tract are needed.

First Report of Dolabra nepheliae Associated with Corky Bark Disease of Rambutan and Pulasan in Honduras

In the last decade, rambutan (Nephelium lappaceum L., Sapindaceae) and pulasan (N. mutabile Blume) have been cultivated in Honduras to produce exotic fruits for export to North America (2). Recently, a disease was observed that produces dark brown to black fissured cankers from 1 to 3 cm long and 1 to 4 cm wide. The infected bark tissue becomes swollen with the middle region 3 to 8 mm thick. Symptoms appear when the trees are approximately 3 years old. As the trees mature, the cankers increase in size and weaken the branches, often resulting in breakage with the weight of the fruit causing substantial plant damage and fruit loss. In August 2010, fissured branch samples of rambutan and pulasan were collected from 6- to 8-year-old trees from the Humid Tropical Demonstrative Agroforestry Center in Honduras, Atlantida, La Masica (15°33'47.4″N, 87°05'2.5″W, elevation 106 m). A fungus associated with the cankers was identified as Dolabra nepheliae. It produces black, stipitate, elongate ascomata, 312 to 482 × 250 to 281 μm with broadly cylindric, bitunicate asci, 120 to 138 × 11.2 to 15.0 μm, and filiform, hyaline ascospores, 128 to 135 × 2.8 to 3.2 μm. Fungi from rambutan and pulasan were isolated on cornmeal agar plus 0.5% dextrose and antibiotics. On potato dextrose agar, the ascospores produced slow-growing colonies, 5 mm per week. In culture, isolates from both hosts produced pycnidia with elongated, slightly to strongly curved or S-shaped, hyaline conidia, 22.8 to 46.4 × 2.8 to 3.7 μm. This fungus was first reported on rambutan and pulasan from Malaysia (1,4), and later reported on rambutan and litchi in Hawaii and Puerto Rico (3). To our knowledge, this is the first report of D. nepheliae on pulasan and rambutan from Honduras. Specimens have been deposited at the U.S. National Fungus Collections (BPI 882442 on N. lappaceum and BPI 882443 on N. mutabile). Cultures were deposited at the Centraalbureau voor Schimmelcultures (CBS) as CBS 131490 on N. lappaceum and CBS 131491 on N. mutabile. Sequences of the internal transcribed spacer (ITS) region including ITS1, 5.8S, and ITS2 intergenic spacers were deposited in GenBank (Accession No. JQ004281 on N. lappaceum and Accession No. JQ004280 on N. mutabile). A BLAST search and pairwise comparison using the GenBank web server were used to compare ITS sequence data and recovered the following results: (i) CBS 131490 on N. lappaceum is 99% (538 of 544) identical to D. nepheliae CBS 123297 on Litchi chinensis from Puerto Rico; and (ii) CBS 131491 on N. mutabile is 99% (527 of 533) identical to the same strain of D. nepheliae. On the basis of the ITS sequence data, the isolates from Honduras were confirmed as the same species, D. nepheliae from Puerto Rico. Efforts to develop resistant germplasm and management strategies to control this disease have been initiated. References: (1) C. Booth and W. P. Ting. Trans. Brit. Mycol. Soc. 47:235, 1964. (2) T. Ramírez et al. Manual Para el Cultivo de Rambutan en Honduras. Fundación Hondureña de Investigación Agrícola. La Lima, Cortes, Honduras, 2003. (3) A. Y. Rossman et al. Plant Dis. 91:1685, 2007. (4) H. Zalasky et al. Can. J. Bot. 49:559, 1971.

CT-angiography for the detection of a lower gastrointestinal bleeding source

The evaluation of lower gastrointestinal bleeding (LGIB) often involves the collaborative efforts of the gastroenterologist, radiologist, and surgeon. Efforts to localize the acute LGIB have traditionally involved colonoscopy, technetium-labeled red blood cell (RBC) scintigraphy, angiography, or a combination of these modalities. The sensitivity of each method of diagnosis is limited, with the most common cause of a negative study the spontaneous cessation of hemorrhage. Other technical factors include vasospasm, lack of adequate contrast volume or exposure time, a venous bleeding source, and a large surface bleeding area. We report the use of multidetector computed tomography (MDCT), or CT-angiography (CT-A), in the initial evaluation of LGIB, and speculate on the incorporation of this technique into a diagnostic algorithm to treat LGIB. MDCT may offer a very sensitive means to evaluate the source of acute LGIB, while avoiding some of the morbidity and intense resource use of contrast angiography, and may provide unique morphologic information regarding the type of pathology. Screening with the more rapid and available MDCT, followed by either directed therapeutic angiography or surgical management, may represent a reasonable algorithm for the early evaluation and management of acute LGIB in which an active bleeding source is strongly suspected.

CT-Angiography for the Detection of a Lower Gastrointestinal Bleeding Source

The evaluation of lower gastrointestinal bleeding (LGIB) often involves the collaborative efforts of the gastroenterologist, radiologist, and surgeon. Efforts to localize the acute LGIB have traditionally involved colonoscopy, technetium-labeled red blood cell (RBC) scintigraphy, angiography, or a combination of these modalities. The sensitivity of each method of diagnosis is limited, with the most common cause of a negative study the spontaneous cessation of hemorrhage. Other technical factors include vasospasm, lack of adequate contrast volume or exposure time, a venous bleeding source, and a large surface bleeding area. We report the use of multidetector computed tomography (MDCT), or CT-angiography (CT-A), in the initial evaluation of LGIB, and speculate on the incorporation of this technique into a diagnostic algorithm to treat LGIB. MDCT may offer a very sensitive means to evaluate the source of acute LGIB, while avoiding some of the morbidity and intense resource use of contrast angiography, and may provide unique morphologic information regarding the type of pathology. Screening with the more rapid and available MDCT, followed by either directed therapeutic angiography or surgical management, may represent a reasonable algorithm for the early evaluation and management of acute LGIB in which an active bleeding source is strongly suspected.

Taenia solium infection in a rural community in the Peruvian Andes

An epidemiological study was conducted in a highland, rural community in Peru, to determine the seroprevalences of human and porcine infection with Taenia solium and the risk factors associated with human infection. The seroprevalences, determined using an assay based on enzyme-linked-immuno-electrotransfer blots (EITB), were 21% (66/316) in the humans and 65% (32/49) in the pigs. The human subjects aged <30 years were more likely to be positive for anti-T. solium antibodies than the older subjects (P < 0.001). The risk factors associated with human seropositivity were lack of education beyond the elementary level [odds ratio (OR)=2.69; 95% confidence interval (CI)=1.09-6.65] and pig-raising (OR=1.68; CI=0.96-2.92). Curiously, sheep-raising was inversely associated with human T. solium infection (OR=0.50; CI=0.28-0.90). The study site appears to be a new endemic focus for T. solium in the central Peruvian Andes. Although, in earlier studies, the seroprevalence of T. solium infection has generally been found to increase with age, the opposite trend was observed in the present study. The results of follow-up studies should help determine if the relatively high seroprevalence in the young subjects of the present study is the result of a transient antibody response.

Efficacy of a competitive enzyme-linked immunosorbent assay (cELISA) for estimating prevalence of immunity to rabbit haemorrhagic disease virus (RHDV) in populations of Australian wild rabbits (Oryctolagus cuniculus)

This study examines the efficacy of a cELISA in estimating the prevalence of immunity to rabbit haemorrhagic disease virus (RHDV) in wild rabbits in Australia. Rabbits (n = 343) captured from six locations in Victoria and Queensland were experimentally challenged with a lethal oral dose (1500 50%-lethal doses, LD50) of RHDV. Death or survival to challenge was used to determine the performance characteristics of the test. The diagnostic specificity, sensitivity and accuracy were highly variable between sites, making it difficult to select a representative cut-off value for all sites that achieved a reasonable level of accuracy for the prediction of surviving and non-surviving rabbits. Estimates of prevalence of immunity were biased owing to effects of site of capture (time of capture) and age structure of the population. Using predictive equations, the best estimates of survival were ±10% but these results came from a limited range of sites, all of which had survival in the range 49–70%. The cELISA will determine whether the RHDV is present in rabbit populations but it should be used with caution when estimating the prevalence of immunity to RHDV. The cELISA may thus be limited in its application for examining the epidemiology of RHDV in Australian rabbit populations.

Interleukin-2 binds to ganglioside GD(1b)

We have developed a solid matrix immunoassay to determine the binding of interleukin-2 (IL-2) to specific gangliosides. The assay establishes that recombinant human IL-2 binds to ganglioside GD(1b) but not to any other gangliosides (GM(1), GM(2), GM(3), GD(1a), GD(2), GD(3), and GT(1b)). The binding varies with the ratio of GD1b and IL-2. This assay enables distinguishing the nature of the sugar moiety of the ganglioside recognized by IL-2 and establishes the dosimetry of the ganglioside-IL-2 interaction. Since rIL-2 is administered systematically into stage IV melanoma patients, we have examined 45 tumor biopsies for GD(1b) content. The incidence of GD(1b) in tumor biopsies is 51%. We postulate that GD(1b) associated on the tumor or in the circulation of cancer patients may bind to rIL-2 and prevent the availability of rIL-2 to augment antitumor-immune response.

Does human melanoma express carcinoembryonic antigen?

BACKGROUND

Several investigators have proposed that carcinoembryonic antigen (CEA), an immunogenic antigen expressed by colon carcinoma, may also be expressed by human melanoma. Because sialyl Lewisx (sLex), the carbohydrate moiety of CEA, has been identified in melanoma, we compared CEA and sLex levels in colon carcinoma cells and melanoma cells.

METHODS

CEA levels were assessed for expression on the cell surface and in cell lysates of cutaneous melanoma cell lines by two different kinds of ELISA, and by Western blot analysis of immunoprecipitated CEA using monoclonal antibodies (Mabs) T84-66 and COL-1, which have defined specificities for CEA. Colon carcinoma cells and purified CEA were positive controls.

RESULTS

Both Mabs reacted strongly with cell surface and cell lysates of colon cancer. Mab T84-66 reacted well with cell surface but not cell lysates of melanoma. COL-1 reacted poorly with cell surface but its binding increased with the density of melanoma cell lysates. Both Mabs intensely stained the blots of purified CEA and colon carcinoma lysates immunoprecipitated with the respective Mabs, but failed to stain the immunoprecipitates of melanoma cell lysates. Both Mabs bound to lysates immunoprecipitated with anti-sLex Mab in colon carcinoma, but not in melanoma. Cell-surface expression of CEA and sLex was significantly correlated (r2: 0.88) in colon cancer cells but not in melanoma.

CONCLUSION

Our results confirm the presence of CEA in colon carcinoma but not in human cutaneous melanoma cell lines.

Gangliosides as targets for immunotherapy for pancreatic adenocarcinoma

BACKGROUND

Pancreatic adenocarcinoma cells express gangliosides and sialyl Lewis (sLe) antigens. It is not known whether these carbohydrate antigens can be targeted by immunotherapy. The authors measured the expression of GM(2) and sLe antigens on the surface of pancreatic carcinoma cells and the serum levels of total gangliosides, GM(2), and antiganglioside antibodies in patients with pancreatic carcinoma.

METHODS

Cell surface GM(2) and sLe antigens were measured by cell suspension enzyme linked immunoadsorbent assay (ELISA) in four pancreatic carcinoma cell lines. Sera from 20 pancreatic carcinoma patients and 20 age- and gender-matched healthy volunteers were analyzed for antiganglioside and anti-sLe immunoglobulin (Ig) M titers by ELISA. Serum levels of total gangliosides and GM(2) also were measured.

RESULTS

All cell lines expressed GM(2) and sLe antigens. When compared with age- and gender-matched volunteers, patients had significantly higher serum levels of total gangliosides (25.6 +/- 9.0 mg/dL vs. 15.6 +/- 2.7 mg/dL; P < 0.001), GM(2) (0.278 +/- 0.415 mg/dL vs. 0.013 +/- 0.018 mg/dL; P = 0.02), ELISA units of anti-GM(2) IgM antibody (368 +/- 95 vs. 155 +/- 25; P = 0.04) and anti-GD(1b) IgM antibody (351 +/- 91 vs. 138 +/- 26; P = 0.03), but not anti-sLe(x) IgM (1389 +/- 345 vs. 1081 +/- 224; P = 0.46) or anti-sLe(a) IgM antibody (1097 +/- 253 vs. 1200 +/- 315; P = 0.80). Patients with unresectable tumors had higher serum levels of total gangliosides compared with patients with resectable tumors, and a serum level > 25 mg/dL was found to correlate significantly with poor overall survival (P < 0.02).

CONCLUSIONS

Increased serum levels of total gangliosides and GM(2) may reflect shedding or release of gangliosides from the surface of tumor cells. Production of IgM antibody against GM(2) and GD(1b) indicates that these gangliosides are immunogenic antigens that may be potential targets for effective active immunotherapy.

Heme oxygenase-1-derived carbon monoxide contributes to the suppression of acute hypertensive responses in vivo

The enzyme heme oxygenase, which exists in inducible (HO-1) and constitutive (HO-2) isoforms, catalyzes the degradation of heme to biliverdin and CO in mammalian tissues. CO has been implicated in the control of vascular tone in a manner similar to that for NO. In the present study, we investigated the contribution of the heme oxygenase/CO pathway to the modulation of acute hypertensive responses in vivo induced by (1) alphaalphaHb, a chemically modified hemoglobin known to scavenge NO, and (2) NG-nitro-L-arginine methyl ester (L-NAME), a competitive NOS inhibitor. Experiments were carried out in conscious rats in which femoral arteries and veins were surgically catheterized 1 or 5 days before treatment with the vasoconstrictor agents. Intravenous infusion of alphaalphaHb (8% solution) or L-NAME (30 micromol/kg) [corrected] produced an acute and significant increase in mean arterial pressure (P<0.05) in rats at 5 days after catheter implantation. In contrast, no change in blood pressure was observed when alphaalphaHb or L-NAME was infused 1 day after the surgical intervention. The suppression of the hypertensive response observed at 1 day after surgery correlated with a significant (P<0.05) HO-1 expression in aorta, heart, and liver as well as increased aortic CO production and cGMP levels. At 1 day after surgery, pretreatment of animals with the heme oxygenase inhibitor zinc protoporphyrin IX (50 micromol/kg IP) markedly decreased aortic CO and cGMP levels and completely restored the vasoconstrictor effects of both alphaalphaHb and L-NAME. These results provide evidence for a crucial role of the heme oxygenase/CO pathway in the regulation of blood pressure under stress conditions in vivo.

Vascular resistance and the efficacy of red cell substitutes in a rat hemorrhage model

We have compared polyethylene glycol-modified bovine hemoglobin (PEG-Hb; high O2 affinity, high viscosity, high oncotic pressure) and human hemoglobin cross-linked between the alpha-chains (alpha alpha-Hb; low O2 affinity, low viscosity, low oncotic pressure) with a non-O2-carrying plasma expander (pentastarch, high viscosity and oncotic pressure) after a 50% (by volume) exchange transfusion followed by a severe (60% of blood volume) hemorrhage. Mean arterial pressure and systemic vascular resistance rose significantly in the alpha alpha-Hb but not in the PEG-Hb animals. Two-hour survival was greater in the PEG-Hb animals (93%) than in control (35%), pentastarch (8%), or alpha alpha-Hb (6%) animals. In the PEG-Hb animals, there was no disturbance of acid-base balance, significantly less accumulation of lactic acid, and higher cardiac output than in the other groups. The data suggest that the rise in vascular resistance that follows alpha alpha-Hb exchange transfusion offsets the additional O2 transport provided by the cell-free hemoglobin. When resistance does not rise, as with PEG-Hb, even relatively small amounts of cell-free hemoglobin appear to be a very effective blood replacement.

Comparison between short or long exposure to 5-fluorouracil in human gastric and colon cancer cell lines: biochemical mechanism of resistance

Recent preclinical and clinical data indicate that the main mechanisms of 5-fluorouracil (5-FU) cytotoxicity depend on the mode of administration. To gather further insight into the major causes of acquired 5-FU resistance, drug-sensitive human gastric (M2), colon (HT29) and breast (MCF7) cancer cell lines were repeatedly exposed to a fixed concentration of 5-FU given either for 1 or 24 h. Although equieffective doses (IC50) of 5-FU were used, resistance to a 1 h exposure of 5-FU developed faster in all models than to a 24 h exposure. Cell lines with acquired resistance to a 1 h application of 5-FU were only partly cross-resistant to a 24 h exposure, whereas lines with resistance to protracted application of 5-FU displayed significant cross-resistance to the 1 h schedule. Resistance to methotrexate was only seen in cell lines with acquired resistance to 24 h of 5-FU. All 5-FU-resistant cell lines showed reduced incorporation of 5-FU into cellular RNA. Furthermore, elevations of thymidylate synthase were seen in all cell lines with resistance to 24 h of 5-FU but also in one cell line with resistance to a bolus schedule. No alterations in folylpolyglutamate synthase developed in the resistant cell lines. These data support the concept that the main mechanisms of 5-FU cytotoxicity depend on the mode of application. Incorporation of fluorouridine triphosphate into RNA appears to be the most important mechanism of action for 5-FU bolus schedules, whereas inhibition of thymidylate synthase becomes more important as the infusion time is prolonged. These data could have implications on the interaction of 5-FU given at different schedules with various other cytostatic agents.

Arterial blood pressure responses to cell-free hemoglobin solutions and the reaction with nitric oxide

Changes in mean arterial pressure were monitored in rats following 50% isovolemic exchange transfusion with solutions of chemically modified hemoglobins. Blood pressure responses fall into three categories: 1) an immediate and sustained increase, 2) an immediate yet transient increase, or 3) no significant change either during or subsequent to exchange transfusion. The reactivities of these hemoglobins with nitric monoxide (.NO) were measured to test the hypothesis that different blood pressure responses to these solutions result from differences in .NO scavenging reactions. All hemoglobins studied exhibited a value of 30 microM-1 s-1 for both .NO bimolecular association rate constants and the rate constants for .NO-induced oxidation in vitro. Only the .NO dissociation rate constants and, thus, the equilibrium dissociation constants varied. Values of equilibrium dissociation constants ranged from 2 to 14 pM and varied inversely with vasopressor response. Hemoglobin solutions that exhibited either transient or no significant increase in blood pressure showed tighter .NO binding affinities than hemoglobin solutions that exhibited sustained increases. These results suggest that blood pressure increases observed upon exchange transfusion with cell-free hemoglobin solutions can not be the result of .NO scavenging reactions at the heme, but rather must be due to alternative physiologic mechanisms.

Blood volume and cardiac index in rats after exchange transfusion with hemoglobin-based oxygen carriers

We have measured plasma volume and cardiac index in rats after 50% isovolemic exchange transfusion with human hemoglobin cross-linked between the alpha-chains with bis(3,5-dibromosalicyl)fumarate (alpha alpha Hb) and with bovine hemoglobin modified with polyethylene glycol (PEGHb). alpha alpha Hb and PEGHb differ in colloid osmotic pressure (23.4 and 118.0 Torr, respectively), oxygen affinity (oxygen half-saturation pressure of hemoglobin = 30.0 and 10.2 Torr, respectively), viscosity (1.00 and 3.39 cP, respectively), and molecular weight (64,400 and 105,000, respectively). Plasma volume was measured by Evans blue dye dilution modified for interference by plasma hemoglobin. Blood volumes in PEGHb-treated animals were significantly elevated (74.0 +/- 3.5 ml/kg) compared with animals treated with alpha alpha Hb (49.0 +/- 1.2 ml/kg) or Ringer lactate (48.0 +/- 2.0 ml/kg) or with controls (58.2 +/- 1.9 ml/kg). Heart rate reduction after alpha alpha Hb exchange is opposite to that expected with blood volume contraction, suggesting that alpha alpha Hb may have a direct myocardial depressant action. The apparently slow elimination of PEGHb during the 2 h after its injection is a consequence of plasma volume expansion: when absolute hemoglobin (concentration x plasma volume) is compared for PEGHb and alpha alpha Hb, no difference in their elimination rates is found. These studies emphasize the need to understand blood volume regulation when the effects of cell-free hemoglobin on hemodynamic measurements are evaluated.

Microvascular oxygen delivery and interstitial oxygenation during sodium pentobarbital anesthesia

BACKGROUND

Anesthesia may represent a considerable bias in experimental medicine, particularly in conditions of stress (such as hemorrhage). Sodium pentobarbital (PB), widely used for cardiovascular investigations, may impair oxygen delivery by hemodynamic and respiratory depression. The critical issue, however, is whether the microcirculation can still maintain tissue oxygenation during anesthesia. To answer this question, the authors studied the effect of PB anesthesia on subcutaneous microvascular oxygen delivery and interstitial oxygenation in Syrian golden hamsters.

METHODS

Sodium pentobarbital anesthesia was induced by intravenous injection (30 mg/kg body weight) and maintained by a 15-min infusion (2 mg.kg-1.min-1), with animals breathing spontaneously (PB-S) or ventilated with air (PB-V). Systemic parameters evaluated were mean arterial pressure (MAP), heart rate, cardiac index (CI), arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2), base excess, and pH. Microvascular and interstitial oxygen tension (PO2), vessel diameter, red blood cell velocity (vRBC), and blood flow (Qb) were measured in a dorsal skinfold preparation. Microcirculatory PO2 values were determined by phosphorescence decay.

RESULTS

Sodium pentobarbital anesthesia significantly decreased CI, MAP, vRBC, and Qb. During PB infusion, PaO2 values were 56 +/- 12.8 mmHg (PB-S) and 115.9 +/- 14.6 mmHg (PB-V) compared with 69.4 +/- 18.2 mmHg and 61.4 +/- 12.6 mmHg at baseline. However, microvascular PO2 was reduced by 25-55% in both groups, resulting in an interstitial PO2 decrease from 23.9 +/- 5.6 mmHg (control) to 13.1 +/- 9.1 mmHg (PB-S) and 15.2 +/- 7 mmHg (PB-V). Microcirculatory PO2 values were restored 30 min after PB infusion, even though hemodynamic depression and a light anesthetic plane were maintained.

CONCLUSIONS

Sodium pentobarbital anesthesia caused impairment of microvascular oxygen delivery and interstitial oxygenation, effects that were not prevented by mechanical ventilation. Although these effects were restricted to deep anesthetic planes, prolonged hemodynamic depression suggests that caution is warranted when using PB as an anesthetic in cardiovascular investigations.

Phenytoin and cyclosporine A specifically regulate macrophage phenotype and expression of platelet-derived growth factor and interleukin-1 in vitro and in vivo: possible molecular mechanism of drug-induced gingival hyperplasia

Phenytoin (pht) is an anticonvulsant drug commonly used for the prevention of seizures. A common side effect of PHT therapy is gingival hyperplasia, occasionally so severe that it requires surgical intervention. Cyclosporine A (CSA) is a drug widely used for the control of rejection phenomena following solid organ and bone marrow transplantation. A frequent side effect of CSA administration is gingival overgrowth. As yet, the molecular mechanisms of drug-induced gingival hyperplasia are unknown although it has been postulated that certain drugs increase fibroblastic activity through alterations in levels of various growth factors and cytokines. The purpose of this study was to: 1) evaluate monocyte/macrophage platelet-derived growth factor (PDGF) and interleukin (IL)-1 beta production in vitro after exposure to CSA; 2) determine the levels of PDGF-B and IL-1 beta gene expression in minimally inflamed gingival tissues of control patients and PHT-treated patients exhibiting gingival overgrowth as well as patients with severe gingival inflammation; and 3) combine characterization of macrophage phenotype with clinical presentation and expression of PDGF-B and IL-1 beta in gingival tissues from the control and PHT-treated patients. For the in vitro studies, commercial ELISA kits were used to measure PDGF-A/PDGF-B and IL-1 beta levels in conditioned media from rat and human monocyte/macrophage cell cultures. CSA caused a significant elevation of PDGF but did not cause any changes in IL-1 beta levels. For the in vivo studies, quantitative competitive reverse transcription polymerase chain reaction (QC-RTPCR) techniques were utilized to measure PDGF-B and IL-1 beta mRNA levels in experimental groups. PHT-treated patients exhibiting gingival overgrowth demonstrated a significant increase in PDGF-B mRNA compared with minimally inflamed controls. Patients with severe gingival inflammation also demonstrated a significant increase in PDGF-B mRNA however, PHT-induced PDGF-B upregulation is approximately 6 times larger than PDGF-B upregulation produced by inflammation alone. PHT-treated patients exhibiting gingival overgrowth demonstrated no significant increase in IL-1 beta mRNA; however, IL-1 beta mRNA levels in the severely inflamed gingival samples demonstrated a significant increase. Additionally, for the clinical samples, macrophage phenotype was characterized immunohistochemically in adjacent sections using specific monoclonal antibodies for inflammatory and reparative/proliferative phenotypes. There were no significant differences in the numbers of either macrophage phenotype in minimally inflamed gingival tissues; however, in the severely inflamed tissue, there was a significant increase in the inflammatory macrophage phenotype and in the hyperplastic gingival tissue, there was a significant increase in the reparative/proliferative macrophage phenotype. The results of this investigation indicate that the clinical presentation of inflamed and hyperplastic gingival tissues is associated with specific macrophages phenotypes which express the pro-inflammatory cytokine IL-1 beta in inflamed tissues or the essential polypeptide growth factor PDGF-B in PHT-induced hyperplastic tissues.

Techniques in facial identification: computer-aided facial reconstruction using a laser scanner and video superimposition

A facial image was reconstructed from the skull, part of a complete skeleton found in woodland, of a male person who hanged himself from a tree. In addition, video superimposition was carried out with antemortem photographs of a person suspected of being the victim, and a good match was obtained. In a further case, a cheaper video-transparency superimposition was carried out, with identity later being confirmed on the basis of dental records. The techniques and the problems encountered are discussed. According to our experience, 3D computer reconstruction and video superimposition have a useful role in the process of identification, particularly in the early stages of an investigation and when other more definitive methods may not be available.

Diaspirin cross-linked hemoglobin: tissue distribution and long-term excretion after exchange transfusion

This report describes the tissue distribution and long-term (14-day) excretion of hemoglobin cross-linked between the alpha-chains (alpha alpha Hb) with carbon 14-labeled bis(3,5-dibromosalicyl)fumarate. Fully conscious, chronically cannulated rats (n = 40) were treated with a 50% isovolemic exchange transfusion (ET) with solutions of 14C-labeled alpha alpha Hb (8.0 gm/dl) and were then monitored for as long as 14 days. Thirteen tissue types were analyzed for radioactivity by liquid scintillation counting. The highest concentration of label was found in the kidney and in tissues of the reticuloendothelial system (i.e., spleen, bone marrow, and liver). The 14C-labeled alpha alpha Hb did not appear to cross the blood-brain barrier, because radioactivity in the brain was barely detectable. The dose of 14C-labeled alpha alpha Hb (2.4 gm Hb/kg) produced an initial plasma Hb level of 4.6 gm/dl, with a half-life in the plasma of 5.0 hours. The peak concentration in kidney, spleen, and liver occurred at 24 hours after ET, when at least 92% of the 14C-labeled alpha alpha Hb in plasma had been cleared. At 48 hours, red casts were seen in a tiny number of renal tubules in some rats. By 14 days, up to 64% of the injected radioactivity had been recovered in urine and about 10% was recovered in feces. Most excretion occurred 24 to 48 hours after ET. This study demonstrated that 2 weeks were required for the metabolic degradation and elimination of a large dose of alpha alpha Hb in rats.

Acute changes in systemic blood pressure and urine output of conscious rats following exchange transfusion with diaspirin-crosslinked hemoglobin solution

This report describes acute changes in systemic blood pressure and urine output observed after a 50-percent isovolemic exchange transfusion (ET) with diaspirin-crosslinked hemoglobin (alpha alpha Hb). Stroma-free Hb was crosslinked between the alpha chains by using a 14C-labeled diaspirin, bis(3,5-dibromosalicyl)fumarate. Forty conscious, chronically cannulated rats underwent ET with 14C-labeled alpha alpha Hb solution (8.0 g/dL [80 g/L]). This resulted in systemic hypertension for 3 to 4 hours after ET (mean arterial pressure rose from 120 to 145 torr at 1 to 2 hours after ET) and mild bradycardia for 2 to 3 hours (heart rate decreased from 420 to 335 beats/min [bpm] before stabilizing at 360 +/- 10 bpm). This was accompanied by significant diuresis immediately after ET (5- 6-fold increase in urine output, which normalized after 12 hours), and mild hemoglobinuria. The total amount of Hb recovered in the urine was < 5 percent of the injected dose. Reversed-phase high-performance liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirmed the presence of crosslinked alpha alpha Hb molecules in the urine. Renal excretion of radioactivity was significantly greater, with 20 percent of total radioactivity being eliminated within 24 hours. The plasma half-life for alpha alpha Hb was 5 hours (administered dose, 2.4 g Hb/kg body weight). Thus, infusion of alpha alpha Hb caused a transient systemic hypertension, and intramolecular crosslinking alone was not enough to exclude completely the filtration of alpha alpha Hb by the kidneys.

The role of the kidneys in the excretion of chemically modified hemoglobins

Stroma-free hemoglobin (SFHb) can be chemically modified to prolong the intravascular retention (prevent renal filtration), and to improve oxygen delivering capability for use as a red cell substitute. Hb derivatives radioactively tagged with tritium [3H] or 14C were used to study their metabolic fate following clearance from the circulation. Fully conscious, chronically cannulated rats were treated by exchange transfusion (ET). Hb solutions tested were: PLPHb (Hb monovalently reacted with pyridoxal 5'-phosphate); HbXL (Hb crosslinked beta-beta with 2-nor-2-formylpyridoxal 5'-phosphate, or with bis-pyridoxal tetraphosphate); alpha alpha Hb (Hb cross-linked between the alpha-chains using bis-3,5-dibromosalicyl fumarate); and polyHb (polymerized with glutaraldehyde or o-raffinose). Plasma retention (T1/2) was significantly affected by dose and the degree of cross-linking. Urine flow rates all increased transiently above normal. In rats treated with any 64 kDa interdimerically cross-linked Hb, mild hemoglobinuria was evident and kidney tissue had the highest label concentration at all time points (1, 5, 10, 24, 48 hr, 7 d, and 14 days post-ET). For polymerized Hb derivatives, the amount of radioactivity in urine and kidneys was inversely related to the MW of the polyHb molecules. In all rats, regardless of the Hb derivative tested, the majority of radioactivity (dpm's) was excreted in urine. About 75% of all renal excretion of radioactivity occurred from 12-60 hours post-ET. This provided evidence that catabolism of cross-linked Hb's began early, and that the kidneys are primarily responsible for excreting smaller degradation fragments.

Pharmacokinetic studies in the rat on a o-raffinose polymerized human hemoglobin

We have studied the plasma half-life (T 1/2), oxygen-binding affinity (P50), organ distribution, and excretion of the individual molecular weight (MW) components of human hemoglobin polymerized with periodate-oxidized, ring-opened raffinose (oR poly-Hb), following transfusion in the rat. The model was an isovolemic 50% exchange transfusion in the conscious, chronically catheterized rat. Total plasma Hb levels yielded a (T 1/2) of 10 to 11 hr for oR poly-Hb. The T 1/2 values of individual MW components of the poly-Hb as determined by size-exclusion HPLC were approximately: 4 hr for the monomeric fraction (Hb)1, 9 hr for the dimer (Hb)2, and 15 hr for the fraction representing trimers to nanomers (Hb)3-9. The P50 values of plasma samples containing oR poly-Hb (collected from 0-24 hr after exchange) remained unchanged at 28 +/- 3 mmHg. oR stabilized and polymerized Hb were not excreted via the kidneys. Hepatic and renal distribution as well as plasma and renal clearance were determined by liquid scintillation counting using individual tritium [3H] labelled MW components purified from [3H]-oR poly-Hb: (Hb)1/2, (Hb)1, (Hb)2, (Hb)3&4, and (Hb) greater than 9. In kidney, uptake (determined by the relative concentration of radioactivity) decreased with increasing MW of the labelled component. Conversely, in liver, uptake increased with increasing MW. Plasma and renal clearance results were consistent with those obtained by HPLC analysis. Hematocrit levels returned from a 20% post-transfusion level to normal pre-transfusion levels (44%) within 10 days after the exchange.

Pregnancy and relapse of peripheral T cell lymphoma. A case report

A patient was admitted to our hospital, in the 34th week of her pregnancy, who presented a non-Hodgkin lymphoma. The delivery was induced in the 38th week and the newborn baby had no other anomalies than a single umbilical artery and a slight dilation of the cerebral ventricles which receded spontaneously. Peculiar characteristics, not previously described, were a peripheral T cell lymphoma with relapse after 5 years since its remission with chemotherapy.

Effects of hypertonic saline (7.5%)/dextran 70 on human red cell typing, lysis, and metabolism in vitro

The introduction of a 7.5% hypertonic saline/6% dextran 70 (HSD) solution into clinical trials for the treatment of hypovolemic states, and the past concerns regarding the possible interference of dextran with blood serology, prompted us to investigate the effects of HSD on human red-cell typing and stability. HSD was evaluated with fresh and 35-day stored CPDA-1 red cells from 12 healthy donors. A 1:5 mixture of HSD to blood in vitro had no effect on ABO, Rh, and MN typing in both fresh and stored blood. HSD produced no significant lysis with fresh cells and a minimal level with stored blood. No evidence of metabolic or morphologic changes was seen after HSD treatment. The results of this study suggest that the clinical use of HSD for the treatment of hemorrhagic shock will not affect blood group determinations or red-cell stability from stored blood which may be infused after the HSD-treated patient is transported to a hospital.

Response of blood pressure, cardiac output, peripheral resistance, and exercise performance to substitution of calcium blocker for beta-blocker plus thiazide diuretic therapy in patients with both systemic hypertension and mild stable angina

We studied 14 patients to determine whether sustained-release diltiazem is a satisfactory long-term substitute for the combination of propranolol plus hydrochlorothiazide (HCTZ), control phase, in the treatment of systemic hypertension with coexisting chronic stable angina pectoris. All patients had either one- or two-vessel coronary disease and normal left ventricular systolic function. Measurements were made during the control phase and 4 and 8 weeks after substitution of sustained-release diltiazem. Only the sitting blood pressure was available before the control phase (pretreatment). Blood pressure and heart rate were measured with patients supine, sitting, and 5 minutes after standing. Cardiac output was measured in the supine position using a computerized Doppler system, and stroke volume, mean arterial pressure, and total systemic resistance were calculated. Symptom-limited modified Bruce protocol treadmill tests were performed to determine time to onset of 1 mm ST segment depression, time to termination of exercise, reason for cessation of exercise, and maximum rate-pressure product. The patients were initially receiving 160-240 mg/day of propranolol (40-60 mg q.i.d.) plus 25-50 mg/day of HCTZ and, subsequently, 12 of 14 had substitution with 240 mg/day (120 mg b.i.d.) of sustained-release diltiazem, and two received 360 mg/day with one of these patients also receiving 50 mg/day of HCTZ. These patients are a subset of a larger group of patients in whom the response of blood pressure alone has been previously reported. Diltiazem resulted in reduction of blood pressure equivalent to that with the propranolol plus HCTZ combination.(ABSTRACT TRUNCATED AT 250 WORDS)

Dengue infections in the Philippines: clinical and virological findings in 517 hospitalized patients

From May 1983 to January 1984, 517 patients with laboratory confirmed dengue were studied at a hospital in Manila. Secondary dengue infections were diagnosed in 78% of these cases. Peak admission (28%) occurred towards the end of the rainy season in November. Most patients (78%) were less than 15 years old but only 3 were infants. Although some type of hemorrhagic finding occurred in 460 cases (89%), only 110 were classified as dengue hemorrhagic fever and the remainder as dengue fever with hemorrhagic manifestations. The clinical course was usually mild. Gastrointestinal bleeding was present in 65 cases, but only 2 patients developed shock. No fatalities occurred. Dengue 2 was the predominant serotype with 53 isolates, followed by dengue 1 with 48 isolates, dengue 3 with 39 isolates, and dengue 4 with only 8 isolates. Dengue 2 was the only serotype with more isolates from sera with a homologous HI antibody titer greater than 1:20 (57%) than from sera with a homologous HI titer less than or equal to 1:20 (43%). In contrast, most of the dengue 1 isolates (63%) were from sera with a homologous HI antibody titer less than 1:10, and this serotype was strongly associated with primary infections. This study shows that dengue infections remain an important cause of pediatric hospitalization in the Philippines; however, the occurrence of life-threatening dengue hemorrhagic fever as has been described in several other large urban areas of Southeast Asia appears to be rare.

Effect of pharmacologic therapy on angina frequency, ST segment depression during ambulatory ECG monitoring, and treadmill performance in patients with chronic stable mild angina

Fifteen patients aged 55 +/- 6 years (mean +/- SD) with mild, chronic stable angina were evaluated after 2 weeks of sublingual nitroglycerin therapy (control) and also after 12 weeks of treatment with either propranolol, up to 320 mg per day, or nifedipine, up to 120 mg per day, in order to measure signs of ischemia and the response of symptoms to therapy. Compared with the control period, there was a decrease in average daily episodes of angina from 1.0 +/- 0.8 to 0.5 +/- 0.4 with treatment (p = 0.10). There was a significant decrease of greater than or equal to 1.0 mm ST segment depression (both symptomatic and asymptomatic), from 6.1 +/- 6.5 to 1.5 +/- 2.4 episodes per 24 hours, p less than 0.001, and of asymptomatic episodes of ST segment depression, from 3.5 +/- 3.9 to 1.0 +/- 2.1 episodes per 24 hours, p = 0.03. The number of patients who had any episodes of greater than or equal to 1.0 mm ST segment depression on their 24-hour ECG decreased from 14 to 6 (93% to 40% of patients, p = 0.005) with treatment, and the number of patients with any episodes of ST segment depression without symptoms decreased from 11 to 5 (73% to 33% of patients, p = 0.07). There was an insignificant increase in treadmill time from 333 +/- 134 to 380 +/- 156 seconds, and an insignificant decrease in maximum double-product from 16,631 +/- 3,599 to 14,922 +/- 4,086; the number of patients with angina at maximum exercise decreased from 13 to 10 (87% to 67%).(ABSTRACT TRUNCATED AT 250 WORDS)

Phlébotomes du Nicaragua: I. Description de la femelle de Lutzomyia zeledoni Young et Murillo, 1984 (Diptera, Psychodidae), et implication épidémiologique de la présence de Lutzomyia longipalpis sur la façade Pacifique

Les auteurs décrivent la femelle de Lutzomyia zeledoni Young et Murillo, 1984 du Groupe Vespertilionis Theodor, 1965. Cette espèce a été capturée en milieu péridomestique en compagnie de Lutzomyia longpalpis Lutz et Neiva, 1912 répertorié pour la première fois du Nicaragua. Il est mis l'accent sur l'importance épidémiologique de cette dernière espèce récoltée en abondance dans plusieurs stations de la façade pacifique.