Understanding the Benefit of Magnetic Resonance-guided Adaptive Radiotherapy in Rectal Cancer Patients: a Single-centre Study

AIMS

Neoadjuvant chemoradiotherapy followed by surgery is the mainstay of treatment for patients with rectal cancer. Standard clinical target volume (CTV) to planning target volume (PTV) margins of 10 mm are used to accommodate inter- and intrafraction motion of target. Treating on magnetic resonance-integrated linear accelerators (MR-linacs) allows for online manual recontouring and adaptation (MRgART) enabling the reduction of PTV margins. The aim of this study was to investigate motion of the primary CTV (CTVA; gross tumour volume and macroscopic nodes with 10 mm expansion to cover microscopic disease) in order to develop a simultaneous integrated boost protocol for use on MR-linacs.

MATERIALS AND METHODS

Patients suitable for neoadjuvant chemoradiotherapy were recruited for treatment on MR-linac using a two-phase technique; only the five phase 1 fractions on MR-linac were used for analysis. Intrafraction motion of CTVA was measured between pre-treatment and post-treatment MRI scans. In MRgART, isotropically expanded pre-treatment PTV margins from 1 to 10 mm were rigidly propagated to post-treatment MRI to determine overlap with 95% of CTVA. The PTV margin was considered acceptable if overlap was >95% in 90% of fractions. To understand the benefit of MRgART, the same methodology was repeated using a reference computed tomography planning scan for pre-treatment imaging.

RESULTS

In total, nine patients were recruited between January 2018 and December 2020 with T3a-T4, N0-N2, M0 disease. Forty-five fractions were analysed in total. The median motion across all planes was 0 mm, demonstrating minimal intrafraction motion. A PTV margin of 3 and 5mm was found to be acceptable in 96 and 98% of fractions, respectively. When comparing to the computed tomography reference scan, the analysis found that PTV margins to 5 and 10 mm only acceptably covered 51 and 76% of fractions, respectively.

CONCLUSION

PTV margins can be reduced to 3-5 mm in MRgART for rectal cancer treatment on MR-linac within an simultaneous integrated boost protocol.

MRI-guided adaptive radiotherapy for prostate cancer: When do we need to account for intra-fraction motion?

A shift of the daily plan can mitigate target position changes that occur between daily MR acquisition and treatment for MR-linac radiotherapy, but increases the session time. We demonstrated that our workflow strategy and decision-making process, to determine whether a subsequent shift is necessary, is appropriate.

Feasibility of magnetic resonance guided radiotherapy for the treatment of bladder cancer

Whole bladder magnetic resonance image-guided radiotherapy using the 1.5 Telsa MR-linac is feasible. Full online adaptive planning workflow based on the anatomy seen at each fraction was performed. This was delivered within 45 min. Intra-fraction bladder filling did not compromise target coverage. Patients reported acceptable tolerance of treatment.

Whole inactivated equine influenza vaccine: Efficacy against a representative clade 2 equine influenza virus, IFNgamma synthesis and duration of humoral immunity

Equine influenza (EI) is a serious respiratory disease of horses induced by the equine influenza virus (EIV). Surveillance, quarantine procedures and vaccination are widely used to prevent or to contain the disease. This study aimed to further characterise the immune response induced by a non-updated inactivated EI and tetanus vaccine, including protection against a representative EIV isolate of the Florida clade 2 sublineage. Seven ponies were vaccinated twice with Duvaxyn IE-T Plus at an interval of four weeks. Five ponies remained unvaccinated. All ponies were experimentally infected with the EIV strain A/eq/Richmond/1/07 two weeks after the second vaccination. Clinical signs of disease were recorded and virus shedding was measured after experimental infection. Antibody response and EIV-specific IFNgamma synthesis, a marker of cell-mediated immunity, were measured at different time points of the study. Vaccination resulted in significant protection against clinical signs of disease induced by A/eq/Richmond/1/07 and reduced virus shedding when challenged at the peak of immunity. Antigenic drift has been shown to reduce protection against EIV infection. Inclusion of a more recent and representative EIV vaccine strain, as recommended by the OIE expert surveillance panel on equine influenza vaccine, may maximise field protection. In addition, significant levels of EIV-specific IFNgamma synthesis by peripheral blood lymphocytes were detected in immunised ponies, which provided a first evidence of CMI stimulation after vaccination with a whole inactivated EIV. Duration of humoral response was also retrospectively investigated in 14 horses vaccinated under field condition and following the appropriate immunisation schedule, up to 599 days after first immunisation. This study revealed that most immunised horses maintained significant levels of cross-reactive SRH antibody for a prolonged period of time, but individual monitoring may be beneficial to identify poor vaccine responders.

Weight for age charts for children with achondroplasia

To develop accurate weight for age charts for individuals with achondroplasia. These novel weight for age, gender-specific growth curves for achondroplasia patients from birth through 16 years were constructed from a longitudinal, retrospective, single observer cohort study of 334 individuals with achondroplasia. Weight for age data from 301 subjects in this achondroplasia cohort, constituting 1,964 total weight measurements, are presented in these weight for age curves. Percentiles (5, 25, 50, 75, 95th) were estimated across the age continuum by gender, using a 1 month window (+/-0.5 months) around each time point of interest. Percentiles were smoothed using a quadratic, penalized smoother by a semi-parametric model approach. Raw weight data from the achondroplasia cohort are compared to that of average stature children presented in the current CDC growth curves, divided into 0-36 months and 2-16 years. There was overlap of birth weight between achondroplasia and average stature infants. This statistical modeling method can be applied to other anthropometric parameters collected from this achondroplasia cohort (e.g., length, BMI), other skeletal dysplasia diagnoses, and to syndromic, non-skeletal dysplasia diagnoses which may benefit from standardization of weight for age.

Reduction in phosphorylated heavy neurofilament in the cerebellum in HIV disease

In the absence of significant neuronal infection HIV induces neuronal damage and death. The pathogenesis of this process is not clear and can only be assessed in the HIV infected brain by examining surviving neuronal populations. Cerebellar Purkinje cells are a model population. We have already demonstrated glutamate receptor alterations in these neurons in AIDS, and in the current study we have investigated the phosphorylation status of heavy neurofilament (NF-H), which is under the control of various intracellular kinases. While the number of Purkinje cells expressing non-phosphorylated NF-H was unchanged, the number of Purkinje cells expressing phosphorylated NF-H was decreased by 36% in the HIV group. This may be a marker of neuronal damage, and possibly indicate alteration in the activity of various intracellular signalling kinase pathways in the HIV infected brain.

Tuberculosis and poverty in the ethnic minority population of West Yorkshire: an ecological study

The rising incidence of TB in the UK in the last decade has been attributed mainly to the persistently high TB rates amongst ethnic minority groups. The epidemiology of TB in these groups is presently poorly understood. The aim of this ecological study was to investigate the relationship between TB and poverty in the South Asian ethnic groups. TB notification rates in South Asians residing in Kirklees (West Yorkshire) were correlated with eight indices of deprivation. Spearman's correlation coefficient analysis suggested a strong relationship between notification rates and material deprivation (r = 0.58 [p value = 0.009 for a two-tailed test]). A similar association was also observed for unemployment (r = 0.51 [p value = 0.02 for a two-tailed test]), but not for overcrowding. This study suggests a link between TB and deprivation in ethnic minority groups in the UK.

Tyrosine-phosphorylated low density lipoprotein receptor-related protein 1 (Lrp1) associates with the adaptor protein SHC in SRC-transformed cells

v-Src transforms fibroblasts in vitro and causes tumor formation in the animal by tyrosine phosphorylation of critical cellular substrates. Exactly how v-Src interacts with these substrates remains unknown. One of its substrates, the adaptor protein Shc, is thought to play a crucial role during cellular transformation by v-Src by linking v-Src to Ras. We used Shc proteins with mutations in either the phosphotyrosine binding (PTB) or Src homology 2 domain to determine that phosphorylation of Shc in v-Src-expressing cells depends on the presence of a functional PTB domain. We purified a 100-kDa Shc PTB-binding protein from Src-transformed cells that was identified as the beta chain of the low density lipoprotein receptor-related protein LRP1. LRP1 acts as an import receptor for a variety of proteins and is involved in clearance of the beta-amyloid precursor protein. This study shows that LRP1 is tyrosine-phosphorylated in v-Src-transformed cells and that tyrosine-phosphorylated LRP1 binds in vivo and in vitro to Shc. The association between Shc and LRP1 may provide a mechanism for recruitment of Shc to the plasma membrane where it is phosphorylated by v-Src. It is at the membrane that Shc is thought to be involved in Ras activation. These observations further suggest that LRP1 could function as a signaling receptor and may provide new avenues to investigate its possible role during embryonal development and the onset of Alzheimer's disease.

Circular forms of unintegrated human immunodeficiency virus type 1 DNA and high levels of viral protein expression: association with dementia and multinucleated giant cells in the brains of patients with AIDS

Thirty-one histologically abnormal brains from patients with AIDS were studied in order to establish the relationship between multinucleated giant cells, viral protein expression, the various forms of human immunodeficiency virus type 1 (HIV-1) DNA, and clinical evidence of dementia. Unintegrated HIV-1 DNA of 2 to 8 kb was found in 22 of the 31 brains. Multinucleated giant cells without any other pathology were found in 14 cases; unintegrated 1-long terminal repeat (1-LTR) circular forms of HIV-1 DNA and strongly positive immunohistochemistry for gp41 and p24 were found in most of these brains. Most of these patients had a clinical diagnosis of HIV-1-associated dementia and cerebral atrophy. In all the other brains studied, 1-LTR circles were absent and immunohistochemistry for gp41 and p24 was usually negative. Very few of these patients had a clinical diagnosis of dementia. Sequence comparison of the LTR region from integrated HIV-1 DNA with that from unintegrated 1-LTR circular forms of HIV-1 DNA in 12 cases showed no significant differences. A further comparison of these brain-derived LTR sequences with LTR sequences derived directly from lymphoid tissue also showed strong sequence conservation. The V3 loop of the virus from the brain was sequenced in 6 cases and had a non-syncytium inducing-macrophage-tropic genotype. Our results show that (i) although unintegrated HIV-1 DNA was present in most brains from patients with AIDS, molecular evidence of high levels of viral replication was associated with the presence of multinucleated giant cells and dementia, and that (ii) the HIV-1 LTR is not a determinant of neurotropism. These observations suggest that replication of HIV-1 and not just the presence of HIV-1 DNA within giant cells makes the important contribution to central nervous system damage.

Beyond CAGE. A brief clinical approach after detection of substance abuse

Generalist physicians should incorporate alcohol and drug abuse detection and brief intervention in the care of their patients. A suggestion of alcohol or drug abuse or a positive response to the CAGE questions deserves further assessment such as clarification about adverse consequences, inquiry about loss of control, determination of the patient's perception of the substance use, and an assessment of the patient's readiness to change behavior. Brief intervention with the patient in the clinical setting about alcohol or drug use can be effective. Motivational interviewing, a directive, patient-centered counseling style for enhancing motivation for change, can make brief interventions more effective by incorporating the patient's readiness to address alcohol or drug use. A useful clinical approach is presented that is tailored to the patient's stage of readiness to change alcohol or drug abuse behavior.

Assessment of neuronal density in the putamen in human immunodeficiency virus (HIV) infection. Application of stereology and spatial analysis of quadrats

Human immunodeficiency virus causes neuronal loss in various brain regions, but it has not been reported in the putamen. However, decrease in the volume of the putamen has been observed by magnetic resonance imaging. In order to clarify this issue two complementary methods; the stereological probe, the disector, and spatial analysis of quadrats, were applied in nondemented individuals who had died of acquired immune deficiency syndrome. A 21% decrease in neuronal density was observed in the human immunodeficiency virus group, especially those cases with human immunodeficiency virus encephalitis; however the statistical significance of this finding was borderline.

Right ventricular infarction: a clinical case study

In this article we review the specific case of Mrs. F., a 63-year-old white woman who recently had classical right ventricular infarction associated with left ventricular inferior wall myocardial infarction. The presentation covers her medical history, clinical course pathophysiology of the right ventricular infarction, and goals of the medical modalities used in treatment. Nursing problems are identified specifically related to right ventricular infarcts, and treatment considerations are discussed. A brief conclusion recaps Mrs. F.'s discharge course and reviews some specific problems associated with right ventricular infarcts, of which critical care nurses need to be aware.

Mechanistic studies on the metabolic chiral inversion of R-ibuprofen in the rat

Deuterium labeling techniques and stereoselective GC/MS methodology have been employed to investigate the mechanism by which R-ibuprofen undergoes metabolic chiral inversion in the rat in vivo. Following oral administration of a mixture of R-ibuprofen (7.5 mg kg-1) and R-[ring-2H4; 2-2H]ibuprofen (R-[2H5]ibuprofen) (7.5 mg kg-1) to male Sprague-Dawley rats, the enantiomeric composition and deuterium excess of the drug were determined in serial plasma samples and in pooled urine collected over 10 hr. The results demonstrate that: (i) R-ibuprofen undergoes extensive inversion of configuration to its S antipode in the rat; (ii) chiral inversion of R-[2H5]ibuprofen yields S-[2H4]ibuprofen in a process that involves quantitative loss of the deuterium atom present originally at C-2; (iii) labeling of R-ibuprofen with deuterium at C-2 does not introduce a measurable kinetic deuterium isotope effect on the chiral inversion reaction; and (iv) metabolism of R-[2H5]ibuprofen leads to the appearance in plasma and urine of molecules of R-ibuprofen labeled with 4 atoms of deuterium. On the basis of these findings, a mechanism is proposed for the chiral inversion reaction that invokes the stereoselective formation of the coenzyme A thioester of R-ibuprofen as a key metabolite; conversion of this species to the corresponding enolate tautomer affords a symmetrical intermediate through which racemization of ibuprofen occurs in vivo.

Psychiatric UR worksheet

This worksheet was developed in response to an ever increasing number and intensity of admission and concurrent telephone reviews conducted by third and fourth-party payors. This worksheet was developed as an aid in information gathering for subsequent telephone and other reviews. The left-margin headings evolved from queries for information from the most demanding psychiatric nurse reviewers. When I have fully addressed all the information in my review, it is usually no problem in obtaining certification for admission or continued stay for the patient.

Enantiotopic differentiation during the biotransformation of valproic acid to the hepatotoxic olefin 2-n-propyl-4-pentenoic acid

The enantiomers of 2-[( 3-13C]-n-propyl)pentanoic acid [(R)- and (S)-[13C]VPA] were employed as metabolic probes to investigate stereochemical aspects of the biotransformation of valproic acid (VPA) to 2-n-propyl-4-pentenoic acid (delta 4-VPA), a hepatotoxic metabolite of VPA. When incubated with hepatocytes freshly isolated from untreated male rats, each labeled substrate (initial concentration 1.0 mM) underwent metabolism to [13C]-delta 4-VPA, the formation of which was time-dependent and occurred at a rate of ca. 20 ng/(10(6) cells.4-h incubation). Analysis of this unsaturated metabolite by GC-MS techniques revealed that, following incubation of (R)-[13C]VPA, desaturation had taken place preferentially (by a factor of approximately 4) on the labeled propyl group (i.e., on the R side chain). Parallel incubations with (S)-[13C]VPA supported this conclusion, in that metabolism of this isotopic variant of VPA led to a terminal olefin that also was predominantly (83 +/- 2%) of R configuration (in this case oxidized selectively on the unlabeled side chain). Hence, biotransformation of VPA to delta 4-VPA in rat hepatocytes occurs with marked enantiotopic differentiation, favoring production of the R enantiomer of this chiral metabolite. When rats were pretreated with phenobarbital (80 mg kg-1 day-1 ip for 3 days) prior to isolation of hepatocytes, the overall rate of metabolism of VPA to delta 4-VPA over the 4-h incubation period increased approximately 3-fold, while the degree of product enantioselectivity was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Enantioselective synthesis and preliminary metabolic studies of the optical isomers of 2-n-propyl-4-pentenoic acid, a hepatotoxic metabolite of valproic acid

The enantiomers of 2-n-propyl-4-pentenoic acid (delta 4-VPA), a known hepatotoxic metabolite of 2-n-propylpentanoic acid (valproix acid, VPA), were synthesized with the aid of the chiral auxiliaries (4S)-4-(2-propyl)-2-oxazolidone and (4R,5S)-4-methyl-5-phenyloxazolidone. Alkylation of the n-valeryl derivatives of these oxazolidones with allyl bromide, followed by reductive cleavage and chromic acid oxidation of the product, afforded the desired acids, (R)- and (S)-delta 4-VPA. Greater than 93% enantiomeric excess was achieved in the preparation of both enantiomers. Preliminary studies on the metabolic fate of (R)- and (S)-delta 4-VPA in freshly isolated rat hepatocytes revealed striking differences in the biotransformation of the two enantiomers. Quantification of two major metabolites of delta 4-VPA, viz., 4,5-diOH-VPA gamma-lactone and 2-n-propyl-2(E),4-pentadienoic acid (delta 2E,4-VPA), indicated that larger amounts of the gamma-lactone were formed in incubations utilizing (R)-delta 4-VPA as substrate, whereas production of the diene was greater in incubations with (S)-delta 4-VPA. On the basis of the premise that delta 4-VPA serves as a mechanism-based irreversible inhibitor of enzymes of the fatty acid beta-oxidation complex, these differences in metabolism suggest that the two enantiomers of delta 4-VPA may differ in their hepatotoxic potential.

Studies on the metabolic fate of valproic acid in the rat using stable isotope techniques

1. The metabolic fate of two specifically deuterated analogues of valproic acid (VPA), [2-2H1]VPA and [3,3-2H2]VPA, was studied in the rat following i.p. injection. 2. A total of 11 urinary metabolites of each labelled substrate were detected by g.l.c.-mass spectrometry. Those metabolites which resulted from oxidation of the drug at C-4 and/or C-5 retained the deuterium label(s), whereas products of oxidation at C-2 and/or C-3 exhibited varying degrees of deuterium loss. 3. The deuterium content of 3-hydroxy-VPA indicated that this metabolite has a dual origin, and arises in part by beta-oxidation of VPA and in part by direct hydroxylation at C-3. An apparent intramolecular isotope effect (kH/kD) of ca. 8 was associated with the latter process. 3-Oxo-VPA appeared to be formed mainly by oxidation of delta 2-VPA, rather than by oxidation of 3-hydroxy-VPA. 4. Evidence was obtained that delta 3-VPA is formed reversibly from delta 2-VPA, and that further desaturation of delta 3-VPA gives rise to a metabolite believed to have a 2,3'-diene structure. 5. The stable isotope method employed in this investigation represents a powerful technique for studies on the origin of drug metabolites and for the elucidation of complex metabolic inter-relationships in vivo.

Intraspecies individuality for the metabolism of steroids

A variety of regulatory factors contribute to differences in the rates of 6 beta-hydroxylation, 16 alpha-hydroxylation and 21-hydroxylation of progesterone as catalysed by liver microsomes prepared from individual rabbits. It is likely that the 6 beta-hydroxylation of progesterone is catalysed primarily by cytochrome P-450 3c, an enzyme that exhibits allosteric activation by alpha-napthoflavone, and by a form of P-450 3b, 6 beta+, that is expressed in some rabbits in an autosomal dominant manner. The mechanism of activation for P-450 3c appears to reflect an effector mediated increase of the affinity of the enzyme for substrate as judged by substrate binding studies. A second form of P-450 3b, 6 beta-, catalyses a major portion of hepatic progesterone 16 alpha-hydroxylation and exhibits activation by a variety of C21 steroids of which 5 beta-pregnane-3 beta,20 alpha-diol is the most efficacious. P-450 1, which catalyses the 21-hydroxylation of progesterone, is expressed at 10-fold higher levels in the 21H phenotype than the 21L phenotype, and the former is inherited as an autosomal dominant characteristic. A cDNA encoding a P-450 1-related gene product exhibits a predicted amino acid sequence that is 95% homologous to that of P-450 1. The P-450 1-related gene product is expressed in liver to a similar degree in both 21H and 21L rabbits.

Rabbit endocervical epithelium: morphometric analysis of secretory cell populations

In this report we quantitated ultrastructural changes in two cytologically distinct secretory cell populations from the rabbit endocervix. Type I and type II cells from estrous animals differ only in the presence of one or more empty cytoplasmic vacuoles in type II cells. Comparing type II cells from 5-day pseudopregnant (PSP) rabbits with type II cells from estrous controls, there is no increase (P greater than .05) in the average vacuole volume. When type I and type II cells from PSP animals are compared to cells from estrous controls, there is a decrease (P less than .01) in the average cell volume, a decrease (P less than .01) in the average nuclear volume, and a decrease (P less than .01) in the average granule volume. This reduction in the granule content of secretory endocervical cells was correlated with a dramatic decrease in protein glycosylation into the microsomal fraction. Serum estradiol concentrations for estrous (13.7 +/- 1.0 pg/ml) and PSP (18.1 +/- 1.5 pg/ml) animals were comparable. However, the 36-fold increase in serum progesterone concentrations for PSP (12.04 +/- 1.7 ng/ml) animals compared to estrous (0.33 +/- 0.1 ng/ml) animals may be responsible for the decrease in protein glycosylation.

Multiple gene-like sequences related to the rabbit hepatic progesterone 21-hydroxylase cytochrome P-450 1

Rabbits exhibit phenotypic differences, 21H and 21L, in the rate of hepatic progesterone 21-hydroxylation that reflect 10-fold higher microsomal concentrations of cytochrome P-450 1 in 21H rabbits. A cDNA library in pBR322 was prepared from liver mRNA isolated from a 21H rabbit. A clone, p1-8, producing a hybrid protein resulting from the insertion of the cDNA into the beta-lactamase gene of the plasmid expressed 5 distinct epitopes that were recognized by a panel of monoclonal antibodies developed toward P-450 1. RNAs selected from total hepatic mRNA by filter hybridization with p1-8 yield at least two electrophoretically distinct proteins when translated in vitro and immunoprecipitated with the 3C3 monoclonal antibody. Only one of the two proteins is recognized by the 1F11 monoclonal antibody, which is highly specific for P-450 1, and the immunoprecipitated protein exhibits the electrophoretic mobility of P-450 1. The other protein remains unidentified. Northern blot analysis indicates that the 3' noncoding portion of p1-8 hybridizes to higher steady state concentrations of polyadenylated RNA in the 21H as compared to 21L rabbits. This correspondence in expression with that of P-450 1 in the 21H and 21L phenotypes further suggests that p1-8 encodes P-450 1 or a closely related protein. The cDNA is 1871 base pairs in length and encodes a protein of 487 amino acids. Southern blot analysis indicates that several independent, gene-like sequences hybridize with the 3' noncoding region of p1-8 under conditions of high stringency. These results indicate that P-450 1 is a member of an extensive multigene family.

An improved method of assessing topical corticosteroid activity

Topical application of ointment bases causes varying degrees of epidermal thickening in guinea-pigs. This is reproducible and can be accurately measured. Suppression of these changes was produced by addition of beta-methasone 17-valerate, fluocinolone acetonide, fluocinonide and hydrocortisone acetate. The inhibitory effect of these steroids was related to the type of corticosteriod, its concentration and the ointment base. The effect was still evident at extremely high dilutions of the steroids and could be measured at concentrations as low as 5 X 10(-5) % of fluocinonide in FAPG. This technique has the merits of being reproducible, sensitive and accurate. It should find a place among existing methods in assaying the efficacy of topical corticosteroids and in aiding in the selection of bases most suitable for formulation of these preparations.