MRI and PET of delayed heavy-ion radiation injury in the rabbit brain

Magnetic resonance imaging (MRI) and positron emission tomography (PET) techniques were used to obtain in vivo scans of delayed (30 GyE helium ion, 230 MeV/u) radiation injury in rabbit brain. T2-weighted (T2W) MRI scans demonstrated alterations that were restricted primarily to the white matter tracts and the deep perithalamic and thalamic regions. Quantitative measurements of T2 and T1 values demonstrated wide variations in absolute values. However, paired comparisons in hemibrain-irradiated rabbits revealed significant increases in T2 (p less than 0.001) and T1 (p less than 0.01) in irradiated versus unirradiated brain. Gadolinium DTPA (GdDTPA) enhanced MRI and 82Rubidium (82Rb) PET detected focal regions of blood-brain barrier (BBB) disruption restricted to the deep white matter and thalamic regions. Sequential GdDTPA enhanced MRI scans showed the spreading of the tracer from the initial site of contrast enhancement. 18Fluorodeoxyglucose (18FDG) PET studies demonstrated the markedly depressed metabolic profiles of irradiated brain. Histological findings of tissue edema and necrosis correlated well with the in vivo imaging abnormalities. These initial studies demonstrate that the irradiated rabbit brain is a suitable animal model for examining the delayed effects of radiation injury in the brain.     

Pancreatoblastoma: a report from the European cooperative study group for paediatric rare tumours (EXPeRT)

Background

Pancreatoblastoma is a very rare malignant tumour typically occurring in the early years of life. Due to its rarity, standardised diagnostic and therapeutic guidelines are not available for pancreatoblastoma.

Methods

The newborn cooperative group denominated EXPeRT – European cooperative study group for paediatric rare tumours – combined in a joint analysis of all cases registered between 2000 and 2009 by the national groups of Italy, France, United Kingdom, Poland and Germany.

Results

Twenty patients <18 years old (median age 4 years) were analysed: nine had distant metastases at diagnosis. Seventeen patients had tumour resection, at initial or delayed surgery. Eighteen received chemotherapy (response rate 73%), seven received radiotherapy. For the whole series, 5-year event-free survival and overall survival were 58.8% and 79.4%, respectively. Outcome did not correlate with tumour site and size, but was strongly influenced by the feasibility of tumour complete resection.

Conclusions

This international study confirms the rarity of the disease, the critical role of surgical resection both as therapy and as a prognostic variable, and the potential efficacy of chemotherapy. The adoption of an intensive multidisciplinary approach is required, as well as the referral to highly experienced centres. Further international cooperation is needed to collect larger series and stimulate biological studies to improve our understanding of the biology and the natural history of PBL.     

Hypofibrinogenaemia with compound heterozygosity for two gamma chain mutations - gamma 82 Ala-->Gly and an intron two GT-->AT splice site mutation

We investigated the molecular basis of hypofibrinogenaemia in a woman with a history of recurrent, pregnancy-associated bleeding, and miscarriage. She had a Clauss fibrinogen of 0.9 mg/ml and SDS PAGE of purified fibrinogen showed a normal pattern of chains. However careful inspection of reverse phase chain separation profiles showed apparent homozygosity for a more hydrophilic form of the gamma chain. DNA Sequencing showed only heterozygosity for a CGT-->GGT (Ala-->Gly) mutation at codon gamma82, but further sequencing showed an additional GT splice sequence mutation at the 5' end of intron 2 of the gamma gene. Translation of mRNA containing this intron would result in premature truncation explaining the phenotypic homozygosity of the gamma82 Ala-->Gly substitution. The patient's sister had a mild bleeding disorder with hypofibrinogenaemia and she too was a compound heterozygote for the y mutations. Her nephew had only the novel splice site mutation, while her mother and daughter inherited only the gamma82 Ala-->Gly substitution.     

Corticotropin-releasing factor microinjection into the central nucleus of the amygdala alters REM sleep

Psychological stressors have a prominent effect on rapid eye movement sleep (REMS) in humans and animals. We hypothesized that the stress-related neurochemical corticotropin-releasing factor (CRF), acting in the amygdala, could initiate neural events that lead to REMS alterations. Therefore, we made bilateral microinjections of three different doses of CRF into the central nucleus of the amygdala (CeA) in five rats. Only the lowest dose of CRF (1 ng) induced a change in sleep, specifically REMS, during the 4-h post-injection period. Thus, REMS alterations following psychological stress may depend, in part, on CRF release in the CeA.     

Alteration of cellular and humoral immunity by mutant p53 protein and processed mutant peptide in head and neck cancer.

PURPOSE: To determine if serologic recognition of p53 mutations at the protein level depends upon the ability of mutant p53 to express new peptide epitopes that bind to human leukocyte antigen (HLA) class II molecules, we used anti-p53 antibody production as a marker for HLA class II-restricted T-cell involvement in head and neck cancer. EXPERIMENTAL DESIGN: An anti-p53 antibody response was correlated with specific p53 mutations and the patients' HLA class II alleles and haplotypes. HLA binding studies and in vitro stimulation (IVS) of peripheral blood mononuclear cells were done using a mutant versus wild-type HLA-DQ7-binding p53 peptide. RESULTS: Certain HLA-DQ and HLA-DR alleles were frequently present in p53 seropositive patients who produced serum anti-p53 antibodies. Selected mutated p53 peptides fit published allele-specific HLA class II binding motifs for the HLA-DQ7 or HLA-DR1 molecules. Moreover, a mutant p53 peptide bound with a 10-fold greater affinity than the wild-type p53 peptide to HLA-DQ7 molecules. IVS of CD4(+) T cells from seven healthy HLA-DQ7(+) donors using this mutant p53 peptide (p53(220C)) was associated with a partial T helper type 2 phenotype compared with IVS using the wild-type p53(210-223) peptide. CONCLUSIONS: Our results support the hypothesis that mutated p53 neoantigens can bind to specific HLA class II molecules, leading to a break in tolerance. This may lead to skewing of the CD4(+) T lymphocyte response toward a tumor-permissive T helper type 2 profile in head and neck cancer patients, as manifested by seropositivity for p53.     

Incidence of adverse events and negligence in hospitalized patients. Results of the Harvard Medical Practice Study I

BACKGROUND. As part of an interdisciplinary study of medical injury and malpractice litigation, we estimated the incidence of adverse events, defined as injuries caused by medical management, and of the subgroup of such injuries that resulted from negligent or substandard care. METHODS. We reviewed 30,121 randomly selected records from 51 randomly selected acute care, nonpsychiatric hospitals in New York State in 1984. We then developed population estimates of injuries and computed rates according to the age and sex of the patients as well as the specialties of the physicians. RESULTS. Adverse events occurred in 3.7 percent of the hospitalizations (95 percent confidence interval, 3.2 to 4.2), and 27.6 percent of the adverse events were due to negligence (95 percent confidence interval, 22.5 to 32.6). Although 70.5 percent of the adverse events gave rise to disability lasting less than six months, 2.6 percent caused permanently disabling injuries and 13.6 percent led to death. The percentage of adverse events attributable to negligence increased in the categories of more severe injuries (Wald test chi 2 = 21.04, P less than 0.0001). Using weighted totals, we estimated that among the 2,671,863 patients discharged from New York hospitals in 1984 there were 98,609 adverse events and 27,179 adverse events involving negligence. Rates of adverse events rose with age (P less than 0.0001). The percentage of adverse events due to negligence was markedly higher among the elderly (P less than 0.01). There were significant differences in rates of adverse events among categories of clinical specialties (P less than 0.0001), but no differences in the percentage due to negligence. CONCLUSIONS. There is a substantial amount of injury to patients from medical management, and many injuries are the result of substandard care.     

Lack of emergence of significant resistance in vitro and in vivo to the new azalide antibiotic azithromycin

In vitro experiments were performed in which 6 to 12 strains ofStaphylococcus aureus, Streptococcus pyogenes, Haemophilus influenzae andEnterobacteriaceae were passaged nine times in sub-lethal concentrations of azithromycin or control antibiotics.Streptococcus pyogenes andStaphylococcus aureus quickly became resistant to rifampin as the MIC90 increased from 0.1 to > 50 µg/ml for both species. The MIC90 of azithromycin, erythromycin, amoxicillin and cefaclor increased by three dilutions forStaphylococcus aureus. The MIC values of azithromycin forStreptococcus pyogenes, Haemophilus influenzae andEnterobacteriaceae strains did not change significantly. However, forHaemophilus influenzae and theEnterobacteriaceae strains, the MIC values of erythromycin and oral cephalosporins increased four-fold. In the in vivo experiments, mice infected withStaphylococcus aureus orEscherichia coli contaminated sutures were administered azithromycin for three days, and on day 6 viable bacterial cells were recovered from the infection site. The sustained tissue concentrations of azithromycin indicated that the organisms would have been continuously exposed to azithromycin at the site of infection. Colonies isolated from azithromycin-treated and non-treated mice were cultured and their susceptibility to azithromycin compared. The azithromycin MIC values forStaphylococcus aureus cultures from treated and non-treated animals were identical. The azithromycin MICs forEscherichia coli recovered from treated animals were on average, less than one dilution higher than for control cultures. Emergence of significant resistance to azithromycin in the laboratory was not observed with the pathogens tested.     

Establishment of a formal program for retinoblastoma: Feasibility of clinical coordination across borders and impact on outcome

Retinoblastoma is an ocular tumor that occurs in young children, in either heritable or sporadic manner. The relative rarity of retinoblastoma, and the need for expensive equipment, anesthesia, and pediatric ophthalmologic expertise, are barriers for effective treatment in developing countries. Also, with an average age‐adjusted incidence of two to five cases per million children, patient number limits development of local expertise in countries with small populations. Lebanon is a small country with a population of approximately 4.5 million. In 2012, a comprehensive retinoblastoma program was formalized at the Children's Cancer Institute (CCI) at the American University of Beirut Medical Center, and resources were allocated for efficient interdisciplinary coordination to attract patients from neighboring countries such as Syria and Iraq, where such specialized therapy is also lacking. Through this program, care was coordinated across hospitals and borders such that patients would receive scheduled chemotherapy at their institution, and monthly retinal examinations and focal laser therapy at the CCI in Lebanon. Our results show the feasibility of successful collaboration across borders, with excellent patient and physician adherence to treatment plans. This was accompanied by an increase in patient referrals, which enables continued expertise development. However, the majority of patients presented with advanced intraocular disease, necessitating enucleation in 90% of eyes in unilateral cases, and more than 50% of eyes in bilateral cases. Future efforts need to focus on expanding the program that reaches to additional hospitals in both countries, and promoting early diagnosis, for further improvement of globe salvage rates.     

Dendritic cells from human tissues express receptors for the immunoregulatory vitamin D3 metabolite, dihydroxycholecalciferol.

Dendritic cells have been isolated from human tonsillar tissue and shown to act as accessory cells in a mitogenic response. The dendritic cells will induced receptors for the active metabolite of vitamin D3, 1,25(OH)2D3, in the responder E+ T cells. The dendritic cells themselves constitutively express receptors for the metabolite, and this distinguishes them from other non-T cells in lymphomedullary tissue. Expression of the 1,25(OH)2D3 receptor may be a dendritic cell property that facilitates their accessory cell role within the tissue microenvironment.