Radiation Safety Observations Associated with 177Lu Dotatate Patients.

Lutetium-177 dotatate, marketed under the name Lutathera®, is proving to be a valuable tool for physicians treating patients with neuroendocrine somatostatin-receptive tumors. Treatment consists of four cycles of 7.4 GBq of Lu dotatate infused intravenously over 30 to 40 minutes. This paper focuses on the radiation safety implications of patients undergoing Lu dotatate treatments at two large medical centers in the United States under the manufacturer's Expanded Access Protocol. Radiation safety precautions are described for the treatment of patients to control for radiation exposure and potential contamination. Ideally, the room used for administration should have a toilet, or one that is in close proximity, and covering should be provided to minimize contamination and clean up. The patient will meet the requirements in 10 CFR Part 35.75 for immediate release based on administered activity or measured exposure rate, but will need to be provided with written instruction on how to keep doses to other individuals ALARA. Disposal of the radioactive waste from Lu dotatate therapy can present some hazard control issues due to the long-lived Lu contaminant.Based on our experience, Lu dotatate therapy is an effective outpatient procedure that can safely occur in any hospital procedural room without the need for additional local shielding. Administration can be accomplished safely with attention paid to the administration set-up and proper administration procedures. Exposure to staff or to adjacent areas is minimal.

The modA10 phasevarion of nontypeable Haemophilus influenzae R2866 regulates multiple virulence-associated traits.

Non-typeable Haemophilus influenzae (NTHi) is a human restricted commensal and pathogen that elicits inflammation by adhering to and invading airway epithelia cells: transcytosis across these cells can result in systemic infection. NTHi strain R2866 was isolated from the blood of a normal 30-month old infant with meningitis, and is unusual for NTHi in that it is able to cause systemic infection. Strain R2866 is able to replicate in normal human serum due to expression of lgtC which mimics human blood group p(k). R2866 contains a phase-variable DNA methyltransferase, modA10 which switches ON and OFF randomly and reversibly due to polymerase slippage over a long tetrameric repeat tract located in its open reading frame. Random gain or loss of repeats during replication can results in expressed (ON), or not expressed (OFF) states, the latter due to a frameshift or transcriptional termination at a premature stop codon. We sought to determine if the unusual virulence of R2866 was modified by modA10 phase-variation. A modA10 knockout mutant was found to have increased adherence to, and invasion of, human ear and airway monolayers in culture, and increased invasion and transcytosis of polarized human bronchial epithelial cells. Intriguingly, the rate of bacteremia was lower in the infant rat model of infection than a wild-type R2866 strain, but the fatality rate was greater. Transcriptional analysis comparing the modA10 knockout to the R2866 wild-type parent strain showed increased expression of genes in the modA10 knockout whose products mediate cellular adherence. We conclude that loss of ModA10 function in strain R2866 enhances colonization and invasion by increasing expression of genes that allow for increased adherence, which can contribute to the increased virulence of this strain.

Operating room radiation exposure in cone beam computed tomography-based, image-guided spinal surgery: clinical article.

OBJECT: Surgeon and operating room (OR) staff radiation exposure during spinal surgery is a concern, especially with the increasing use of multiplanar fluoroscopy in minimally invasive spinal surgery procedures. Cone beam computed tomography (cbCT)-based, 3D image guidance does not involve the use of active fluoroscopy during instrumentation placement and therefore decreases radiation exposure for the surgeon and OR staff during spinal fusion procedures. However, the radiation scatter of a cbCT device can be similar to that of a standard 64-slice CT scanner and thus could expose the surgeon and OR staff to radiation during image acquisition. The purpose of the present study was to measure radiation exposure at several unshielded locations in the OR when using cbCT in conjunction with 3D image-guided spinal surgery in 25 spinal surgery cases. METHODS: Five unshielded badge dosimeters were placed at set locations in the OR during 25 spinal surgery cases in which cbCT-based, 3D image guidance was used. The cbCT device (O-ARM) was used in conjunction with the Stealth S7 image-guided platform. The radiology department analyzed the badge dosimeters after completion of the last case. RESULTS: Fifty high-definition O-ARM spins were performed in 25 patients for spinal registration and to check instrumentation placement. Image-guided placement of 124 screws from C-2 to the ileum was accomplished without complication. Badge dosimetry analysis revealed minimal radiation exposure for the badges 6 feet from the gantry in the area of the anesthesiology equipment, as well as for the badges located 10-13 feet from the gantry on each side of the room (mean 0.7-3.6 mrem/spin). The greatest radiation exposure occurred on the badge attached to the OR table within the gantry (mean 176.9 mrem/spin), as well as on the control panel adjacent to the gantry (mean 128.0 mrem/spin). CONCLUSIONS: Radiation scatter from the O-ARM was minimal at various distances outside of and not adjacent to the gantry. Although the average radiation exposure at these locations was low, an earlier study, undertaken in a similar fashion, revealed no radiation exposure when the surgeon stood behind a lead shield. This simple precaution can eliminate the small amount of radiation exposure to OR staff in cases in which the O-ARM is used.

Adhesin genes and serum resistance in Haemophilus influenzae type f isolates.

The incidence of invasive infections due to Haemophilus influenzae has decreased significantly in developed countries with high rates of vaccination against H. influenzae serotype b (Hib). This vaccine provides no protection against H. influenzae serotype f (Hif), typically associated with invasive infections in adults with chronic disease and/or immunodeficiency, and rarely in otherwise healthy adults and children. The specific properties of Hif associated with virulence remain largely uncharacterized. A panel of 26 Hif strains consisting of both invasive disease-associated and mucosal surface non-invasive disease-associated isolates was surveyed by DNA fingerprinting, biotyping and PCR detection of hmw1, hmw2, hsf, the hif fimbrial locus and the lipo-oligosaccharide (LOS) biosynthetic island, and assessment of ß-lactamase expression and determination of resistance to the bactericidal activity of normal adult human serum. Repetitive sequence-based PCR fingerprinting differentiated the 26 strains into three clusters, with the majority of isolates (22/26, 84.6 %) clustered into a single indistinguishable group. Most isolates (24/26, 92.3 %) were of biotype I and two isolates produced ß-lactamase with detection of a conjugative plasmid, and the isolates displayed a range of resistances to the bactericidal activity of human serum. All 26 isolates carried the adhesin hsf, 21 carried a partial hif fimbrial operon and 4 had the adhesin genes hmw1/2. A LOS biosynthetic island was detected in 20 isolates consisting of the genes lic2BC. It was concluded that Hif has many recognized virulence properties and comprises a relatively homogeneous group independent of the anatomical source from which it was isolated.

Characterization of extended co-culture of non-typeable Haemophilus influenzae with primary human respiratory tissues.

Non-typeable Haemophilus influenzae (NTHi) are human-adapted Gram-negative bacteria that comprise part of the normal flora of the human upper airway, but are also responsible for a number of mucosal infections such as otitis media and bronchitis. These infections often recur and can become chronic. To characterize the effect of long-term co-culture of NTHi with human tissues, we infected primary respiratory epithelial cells grown at the air-liquid interface with three NTHi strains over a range of 1-10 days. Scanning and transmission electron microscopy of tissues confirmed that intact NTHi were persisting paracellularly, while organisms observed in intracellular vacuoles appeared degraded. Furthermore, the apical surface and tight junctions of the infected tissues were undisturbed, with high transepithelial electrical resistances, while the basal cell layer displayed more junctional disorganization and wider intercellular spaces than the uninfected control tissues. Although the tissues elaborated the cytokine profile reported for NTHi-caused otitis media in vivo, there was little change in the dynamics of cytokine secretion over the time points tested. Finally, we report that NTHi strains released outer membrane vesicles (OMVs) during extended co-culture with the tissues, and show that these OMVs directly interact with host cell membranes.

Infant rat infection modifies phenotypic properties of an invasive nontypeable Haemophilus influenzae.

Enhancing the virulence trait of a specific bacterium in an animal model is often performed prior to the use of the strain for ex vivo human studies, such as reactivity with complement and antibody, or with phagocytic cells. For example, in Streptococcus pneumoniae mouse passage is used to enhance capsule production. While investigating an unusual serum-resistant unencapsulated Haemophilus influenzae (R2866), we found that animal passage yielded an isolate (R3392) which had decreased resistance to human serum, but increased virulence in Chang conjunctival cell monolayers, but with less invasion and transcytosis of polar H292 cells. We examined 90 colonies recovered from three infant rats for phase variants of LPS biosynthetic genes. In 88 colonies lgtC was OFF due to tetrameric repeat mediated slipped-strand mispairing at the time of DNA replication, while there was no variation in lic1A, lic2A, lic3A, lexA and oaf A. With lgtC OFF the LPS lacks Galα1-4ßGal, an epitope mimicking the human p(k) blood group, and molecular mimicry is lost. Selection for strain susceptible to NHS in the infant rat was not antibody mediated. We conclude that the passage of pathogens virulent in humans and animals may select for phenotypes only relevant for the animal species used.

Surgeon radiation exposure in cone beam computed tomography-based, image-guided spinal surgery.

BACKGROUND: Radiation exposure to the surgeon is a concern in spinal surgery, especially with the increasing popularity of minimally invasive spinal surgery techniques. Three-dimensional (3D) image guidance used in conjunction with cone beam computed tomography (cbCT) has a theoretical advantage of decreased radiation exposure to the surgeon and operating room (OR) staff. Radiation scatter to the environment immediately surrounding a CT scanner during acquisition of a CT scan is a known entity. This in vivo study measures the radiation exposure to the surgeon when using cbCT registration in 3D image-guided spinal surgery. METHODS: Two badge dosimeters were worn by the surgeon (EWN), one on the right waistband of the surgeon's scrubs and the other located over the thyroid area during 25 consecutive spinal surgery cases in which cbCT was used in conjunction with 3D image guidance. No lead protection was worn by the surgeon. The cbCT device was used for registration of the anatomy and to confirm adequate instrumentation placement. The surgeon stood behind a clear lead shield in the same location during every spin of the cbCT device. After the 25th case, the badge dosimeters were sent to the radiology department for analysis. RESULTS: Overall, 63 cbCT spins were accomplished in 25 patients. A total of 228 screws were placed into spinal levels spanning from C2 to the ileum. No complications resulted from instrumentation placement or the use of image guidance.Analysis of both badge dosimeters revealed 0 millirem (mRem) exposure. CONCLUSIONS: Our study demonstrates that no radiation exposure to the surgeon occurs in cbCT-based, 3D image-guided spinal surgery procedures. Additionally, radiation scatter does not result in surgeon radiation exposure during patient registration if the surgeon stands behind a lead shield 10 feet from the cbCT device and not in direct line with the opening of the cbCT tube.

Analysis of genetic relatedness of Haemophilus influenzae isolates by multilocus sequence typing.

The gram-negative bacterium Haemophilus influenzae is a human-restricted commensal of the nasopharynx that can also be associated with disease. The majority of H. influenzae respiratory isolates lack the genes for capsule production and are nontypeable (NTHI). Whereas encapsulated strains are known to belong to serotype-specific phylogenetic groups, the structure of the NTHI population has not been previously described. A total of 656 H. influenzae strains, including 322 NTHI strains, have been typed by multilocus sequence typing and found to have 359 sequence types (ST). We performed maximum-parsimony analysis of the 359 sequences and calculated the majority-rule consensus of 4,545 resulting equally most parsimonious trees. Eleven clades were identified, consisting of six or more ST on a branch that was present in 100% of trees. Two additional clades were defined by branches present in 91% and 82% of trees, respectively. Of these 13 clades, 8 consisted predominantly of NTHI strains, three were serotype specific, and 2 contained distinct NTHI-specific and serotype-specific clusters of strains. Sixty percent of NTHI strains have ST within one of the 13 clades, and eBURST analysis identified an additional phylogenetic group that contained 20% of NTHI strains. There was concordant clustering of certain metabolic reactions and putative virulence loci but not of disease source or geographic origin. We conclude that well-defined phylogenetic groups of NTHI strains exist and that these groups differ in genetic content. These observations will provide a framework for further study of the effect of genetic diversity on the interaction of NTHI with the host.

Intraoperative gamma probe localization of the ureters: a novel concept.

BACKGROUND: Ureteral stent placement to localize the ureters during operations is an invasive procedure. The aim of this study was to evaluate the feasibility of using the gamma probe to intraoperatively identify the ureters after intravenous injection of a radiopharmaceutical agent. STUDY DESIGN: Ten patients undergoing elective abdominal operations were prospectively enrolled in this study. An average dose of 4.5 mCi (range 2.8 to 5.3 mCi) of technetium Tc 99m-labeled diethylenetriamine pentaacetic acid ((99m)Tc-DTPA) was administered intravenously before localization of the ureters. The gamma probe was used to localize the ureters. Correct identification of the ureters was confirmed when gentle manipulation induced a typical ureteral peristaltic pattern. RESULTS: Gamma counts were significantly elevated in all ureters examined. Compared with background counts, gamma counts were increased over the ureter in all patients, with an average increase of 465%. The technique was modified after use in the first 3 patients and standardized for patients 4 through 10. Data from those seven patients were analyzed. Both ureters were correctly identified using the gamma probe at a mean of 15 minutes (median, 10 minutes) after a single (99m)Tc-DTPA injection (range 4 to 41 minutes). The mean background count was 80 counts per second (cps, range 50 to 130 cps). The mean ureter count was 393 cps (range 128 to 700 cps). The average percent increase of each ureter count compared with its specific background count was 465% (range 256% to 1,077%). The difference was statistically significant for all values (p < 0.001). CONCLUSIONS: This novel technique of gamma probe localization of the ureters may offer a noninvasive approach for ureteral identification.

lgtC expression modulates resistance to C4b deposition on an invasive nontypeable Haemophilus influenzae.

We have previously shown that C3 binding to serum-resistant nontypeable Haemophilus influenzae (NTHi) strain R2866 is slower than C3 binding to a serum-sensitive strain. Ab-dependent classical pathway activation is required for complement-dependent killing of NTHi. To further characterize the mechanism(s) of serum resistance of R2866, we compared binding of complement component C4b to R2866 with a serum-sensitive variant, R3392. We show that C4b binding to R2866 relative to R3392 was delayed, suggesting regulation of the classical pathway of complement. Increased C4b deposition on R3392 was independent of the amount and subclass of Ab binding, suggesting that an impediment to C4b binding existed on R2866. Immunoblotting and mass spectrometry indicated that lipooligosaccharide and outer membrane proteins P2 and P5 were targets for C4b. P2 and P5 sequences and expression levels were similar in both strains. Insertional inactivation of the phase-variable lipooligosaccharide biosynthesis gene lgtC in R2866 augmented C4b deposition to levels seen with R3392 and rendered the bacteria sensitive to serum and whole blood. These results suggest a direct role of lgtC expression in the inhibition of C4b deposition and consequent serum resistance of R2866. Alteration of surface glycans of NTHi may be a critical event in determining the ability of a strain to evade host defenses and cause disseminated infection.

Role of lgtC in resistance of nontypeable Haemophilus influenzae strain R2866 to human serum.

We are investigating a nontypeable Haemophilus influenzae (NTHI) strain, R2866, isolated from a child with meningitis. R2866 is unusually resistant to killing by normal human serum. The serum 50% inhibitory concentration (IC50) for this strain is 18%, approaching that of encapsulated H. influenzae. R3392 is a derivative of R2866 that was found to have increased sensitivity to human serum (IC50, 1.5%). Analysis of tetrameric repeat regions within lipooligosaccharide (LOS) biosynthetic genes in both strains indicated that the glycosyltransferase gene lgtC was out of frame ("off") in most colonies of R3392 but in frame with its start codon ("on") in most colonies of the parent. We sought antigenic and biochemical evidence for modification of the LOS structure. In a whole-cell enzyme-linked immunosorbent assay, strain R3392 displayed reduced binding of the Galalpha1,4Gal-specific monoclonal antibody 4C4. Mass spectrometry analysis of LOS from strain R2866 indicated that the primary oligosaccharide glycoform contained four heptose and four hexose residues, while that of R3392 contained four heptose and three hexose residues. We conclude that the R2866 lgtC gene encodes a galactosyltransferase involved in synthesis of the 4C4 epitope, as in other strains, and that expression of lgtC is associated with the high-level serum resistance that has been observed for this strain. This is the first description of the genetic basis of high-level serum resistance in NTHI, as well as the first description of LOS composition in an NTHI strain for which the complete genome sequence has been determined.

Heterogeneity in tandem octanucleotides within Haemophilus influenzae lipopolysaccharide biosynthetic gene losA affects serum resistance.

Haemophilus influenzae is subject to phase variation mediated by changes in the length of simple sequence repeat regions within several genes, most of which encode either surface proteins or enzymes involved in the synthesis of lipopolysaccharides (LPS). The translational repeat regions that have been described thus far all consist of tandemly repeated tetranucleotides. We describe an octanucleotide repeat region within a putative LPS biosynthetic gene, losA. Approximately 20 percent of nontypeable H. influenzae strains contain copies of losA and losB in a genetic locus flanked by infA and ksgA. Of 30 strains containing losA at this site, 24 contained 2 tandem copies of the octanucleotide CGAGCATA, allowing full-length translation of losA (on), and 6 strains contained 3, 4, 6, or 10 tandem copies (losA off). For a serum-sensitive strain, R3063, with losA off (10 repeat units), selection for serum-resistant variants yielded a heterogeneous population in which colonies with increased serum resistance had losA on (2, 8, or 11 repeat units), and colonies with unchanged sensitivity to serum had 10 repeats. Inactivation of losA in strains R3063 and R2846 (strain 12) by insertion of the cat gene decreased the serum resistance of these strains compared to losA-on variants and altered the electrophoretic mobility of LPS. We conclude that expression of losA, a gene that contributes to LPS structure and affects serum resistance, is determined by octanucleotide repeat variation.

Characterization of genetic and phenotypic diversity of invasive nontypeable Haemophilus influenzae.

The ability of unencapsulated (nontypeable) Haemophilus influenzae (NTHi) to cause systemic disease in healthy children has been recognized only in the past decade. To determine the extent of similarity among invasive nontypeable isolates, we compared strain R2866 with 16 additional NTHi isolates from blood and spinal fluid, 17 nasopharyngeal or throat isolates from healthy children, and 19 isolates from middle ear aspirates. The strains were evaluated for the presence of several genetic loci that affect bacterial surface structures and for biochemical reactions that are known to differ among H. influenzae strains. Eight strains, including four blood isolates, shared several properties with R2866: they were biotype V (indole and ornithine decarboxylase positive, urease negative), contained sequence from the adhesin gene hia, and lacked a genetic island flanked by the infA and ksgA genes. Multilocus sequence typing showed that most biotype V isolates belonged to the same phylogenetic cluster as strain R2866. When present, the infA-ksgA island contains lipopolysaccharide biosynthetic genes, either lic2B and lic2C or homologs of the losA and losB genes described for Haemophilus ducreyi. The island was found in most nasopharyngeal and otitis isolates but was absent from 40% of invasive isolates. Overall, the 33 hmw-negative isolates were much more likely than hmw-containing isolates to have tryptophanase, ornithine decarboxylase, or lysine decarboxylase activity or to contain the hif genes. We conclude (i) that invasive isolates are genetically and phenotypically diverse and (ii) that certain genetic loci of NTHi are frequently found in association among NTHi strains.

Small bowel transit and gastric emptying after biliodigestive anastomosis using the uncut jejunal loop.

BACKGROUND: The Roux-en-Y loop is an effective procedure for biliodigestive drainage. However, up to 15% of patients suffer from postoperative cholangitis or blind loop syndrome. A new technique to prevent motility abnormalities has been developed. METHODS: Male Lewis rats were used to compare gastric emptying and transit in the small bowel after either a standard Roux-en-Y anastomosis or a new biliodigestive anastomosis technique which involves creating an "uncut" jejunal loop with luminal occlusion. Unoperated rats served as controls. (99)Technetium HIDA and (111)Indium-tagged amberlite were respectively used to investigate small bowel transit and gastric emptying. RESULTS: Histopathology showed distinctive abnormalities only in the liver of conventional Roux-en-Y animals. No recanalization of the obliterated gut lumen occurred in uncut Roux animals. Distribution of (99)Tc-HIDA and (111)In showed were similar in both groups. Gastric emptying is slowed in both groups. CONCLUSIONS: The uncut proximal jejunum loop is a good alternative to the conventional Roux-en-Y loop and showed preserved small bowel motility and adequate jejunal transit. Gastric emptying is slowed in both groups.

Skin cancer in an atomic veteran: cause or coincidence?

BACKGROUND: Some military personnel who were exposed to ionizing radiation during atomic weapons tests subsequently developed skin cancer, but the cause-effect relationship is unclear. OBJECTIVE: To explore the possible relationship between exposure to atomic tests and the development of skin cancer. METHODS: We reviewed available literature regarding the effects of radiation on the skin and the case history of a patient in whom more than 300 basal cell carcinomas developed over a 30-year period after exposure to radiation during atomic testing. RESULTS AND CONCLUSIONS: Ionizing radiation can cause skin cancer, usually basal cell carcinoma. In some veterans of atomic testing, skin cancer may have been initiated by ionizing radiation and promoted by ultraviolet radiation. We conclude that exposure to ionizing radiation during atomic weapons testing contributed to the excessive number and location of basal cell carcinomas in our patient.