The inverse square law: A basic principle in brachytherapy

The purpose of this article is to remind the importance of the inverse square law in radiotherapy and especially in brachytherapy. Indeed, beyond the impact in radiation therapy with high energy beam, there is the use of radionuclides and low energy photons with short FSD where it is still more important. Comparisons between Iridium Brachytherapy and low energy X-rays brachytherapy show equivalent dose distributions in the first few centimeters. If the inverse square law is not the only element influencing the dose distributions calculations, it must not be forgotten. And it is playing a major role in brachytherapy with short FSD (<6cm).

Principles of dose-setting in toxicology studies: the importance of kinetics for ensuring human safety

Regulatory toxicology seeks to ensure that exposures to chemicals encountered in the environment, in the workplace, or in products pose no significant hazards and produce no harm to humans or other organisms, i.e., that chemicals are used safely. The most practical and direct means of ensuring that hazards and harms are avoided is to identify the doses and conditions under which chemical toxicity does not occur so that chemical concentrations and exposures can be appropriately limited. Modern advancements in pharmacology and toxicology have revealed that the rates and mechanisms by which organisms absorb, distribute, metabolize and eliminate chemicals-i.e., the field of kinetics-often determine the doses and conditions under which hazard, and harm, are absent, i.e., the safe dose range. Since kinetics, like chemical hazard and toxicity, are extensive properties that depend on the amount of the chemical encountered, it is possible to identify the maximum dose under which organisms can efficiently metabolize and eliminate the chemicals to which they are exposed, a dose that has been referred to as the kinetic maximum dose, or KMD. This review explains the rationale that compels regulatory toxicology to embrace the advancements made possible by kinetics, why understanding the kinetic relationship between the blood level produced and the administered dose of a chemical is essential for identifying the safe dose range, and why dose-setting in regulatory toxicology studies should be informed by estimates of the KMD rather than rely on the flawed concept of maximum-tolerated toxic dose, or MTD.

Acute care for elderly patients in a functional impairment prevention unit

AIM

To determine whether the care of patients with moderate dependency who were hospitalised in a functional impairment prevention unit (FIPU) was superior to that of a conventional unit (CU) in terms of functional impairment and mean stay.

METHODS

We conducted a single-centre, retrospective, controlled intervention study that compared acute treatment in an FIPU and in conventional wards. The study included 466 elderly patients with moderate dependence (Barthel index, 30-70) and older than 75 years. Of these, 280 were included in the intervention group and 186 in the control group. The primary outcomes were loss of functionality attributable to the hospitalisation (measured by the loss of ambulation and urinary continence) and differences in the length of stay.

RESULTS

The patients hospitalised in the FIPU showed less functional impairment as determined by the loss of urinary continence (2.1% of the FIPU patients vs. 9.7% of the CU patients; p<.01) and the loss of walking ability (2.1% vs. 25.3%; p<.01). The patients hospitalised in the FIPU had a shorter mean stay (7.4 vs. 8.5 days; p<.05), with 1 day less of stay than the CU patients.

CONCLUSION

The acute care of elderly patients with moderate dependency in an FIPU was independently associated with less functional decline and shorter stays.

The geology and geophysics of Kuiper Belt object (486958) Arrokoth

The Cold Classical Kuiper Belt, a class of small bodies in undisturbed orbits beyond Neptune, is composed of primitive objects preserving information about Solar System formation. In January 2019, the New Horizons spacecraft flew past one of these objects, the 36-kilometer-long contact binary (486958) Arrokoth (provisional designation 2014 MU₆₉). Images from the flyby show that Arrokoth has no detectable rings, and no satellites (larger than 180 meters in diameter) within a radius of 8000 kilometers. Arrokoth has a lightly cratered, smooth surface with complex geological features, unlike those on previously visited Solar System bodies. The density of impact craters indicates the surface dates from the formation of the Solar System. The two lobes of the contact binary have closely aligned poles and equators, constraining their accretion mechanism.

Draft Genome Sequences of 42 Environmental Vibrio vulnificus Strains Isolated from the Northern Gulf of Mexico

Vibrio vulnificus is a Gram-negative bacterium and an opportunistic pathogen that can cause septicemia or necrotizing fasciitis. Here, we report the draft genome sequences of 42 environmental V. vulnificus strains collected from the northern Gulf of Mexico. These data will allow for more robust comparisons between clinical and environmental strains.

Simulation-based training program with deliberate practice for ultrasound-guided jugular central venous catheter placement

BACKGROUND

Current evidence supports the utility of simulation training for bedside procedures such as ultrasound-guided jugular central venous catheter (CVC) insertion. However, a standardized methodology to teach procedural skills has not been determined yet. The aim of this study was to evaluate the effectiveness of a simulation-based training program for improving novice technical performance during ultrasound-guided internal jugular CVC placement.

METHODS

Postgraduate year 1 (PGY-1) residents from anesthesiology, emergency medicine, cardiology, ICU, and nephrology specialties were trained in four deliberate practice sessions. Learning objectives included principles of ultrasound (US), preparation (gown, glove, draping), procedural skills I (US scanning and puncture), and procedural skills II (catheter insertion). CVC technical proficiency was tested pre- and post-training using hand-motion analysis with the Imperial College Surgical Assessment Device (ICSAD) and a global rating scale (GRS).

RESULTS

Thirty-five PGY-1 residents successfully completed the program. These novices' GRS scores improved significantly after the training (P < 0.001). Total path length measured with the ICSAD decreased significantly after the training (P = 0.008). Procedural time decreased significantly after training from 387 (310-501) seconds to 200 (157-261) seconds (median and interquartile range) (P = 0.029).

CONCLUSION

This simulation-training program based on deliberate practice significantly increased the technical skills of residents in US-guided short-axis, out-of-plane internal jugular CVC placement. Data also confirm the validity of the ICSAD as an assessment tool for ultrasound-guided internal jugular CVC placement learning.

Retinoic acid generates regulatory T cells in experimental transplantation

Regulatory T cells play a key role to inhibit effector lymphocytes, avoid, autoimmunity, and restrain allogeneic immunity. Retinoic acid is an important cofactor that stimulates the generation and expansion of regulatory T cells. Naive T cells, coincubated with allogeneic antigen-presenting cells and retinoic acid, in conjunction with transforming growth factor (TGF) β and interleukin (IL) 2, generated allogeneic regulatory T cells de novo. These cells were able to inhibit skin rejection in adoptive transfer experiments. The generation of regulatory T cells ex vivo with retinoic acid, TGF-β, and IL-2 represents a new step toward specific regulation of allogeneic immune responses.

Persistence profile of polyaromatic hydrocarbons in shallow and deep Gulf waters and sediments: effect of water temperature and sediment-water partitioning characteristics

Persistence profiles of selected polyaromatic hydrocarbons (PAHs) were analyzed depending on temperature variations in the water column and water-sediment interactions in the Gulf of Mexico. The PAHs studied include anthracene, fluoranthene, pyrene, and chrysene. The half-lives of PAHs in the deep waters (over 1000 m) are about twice as long as those in the shallow areas (100-150 m), and almost 2.5 times as long as those in the top layer (0-10 m) of the water column. The half-lives of the PAHs in the sediments are significantly longer. Among the PAHs studied, chrysene is the most persistent in the water column, and pyrene is the most persistent in the sediments. The half-life of chrysene in the shallow and deep waters is over 2.5 and about 5 years, respectively. For pyrene, the half-life in the shallow and deep sediments is about 9 and 16 years, respectively.

Conservative treatment with transurethral resection, neoadjuvant chemotherapy followed by radiochemotherapy in stage T2-3 transitional bladder cancer

PURPOSE

Organ preservation has been investigated in patients (p) with infiltrating transitional cell carcinoma (TCC) of the bladder over the past decade as an alternative to radical cystectomy. This is a trimodal schedule study, including transurethral resection of bladder tumor (TURB), neoadjuvant chemotherapy and concomitant radiochemotherapy (RTC).

PATIENTS AND METHODS

From April 1996 until August 2005, 29 evaluable patients (p) with T2-T3NXM0 bladder cancer were enrolled. After a transurethral resection of bladder tumor (TURB), we administered 2 cycles of induction chemotherapy with CMV (15 p) or Gemcitabine-Cisplatin (14 p) followed by radiotherapy 45 Gy 1.8 Gy/fraction and two cycles of concomitant cisplatin 70 mg/m(2). 2-3 weeks later, a cystoscopy with tumor-site biopsy was performed. If complete histological response, p were treated with consolidation radiotherapy until 64.8 Gy. For p with residual or recurrent tumor, cystectomy was performed.

RESULTS

We included 28 men and 1 women (median age 63, range 39-72 years) with PS (ECOG) 0-1. The stage was: 21 p T2; 6 p T3a; and 2 p T3b. Toxicity was higher in CMV compared with Gem- Cis: grade (3/4) neutropenia 4/15 (26%) vs 1/14 (7%); febrile neutropenia 3/15 (20%) vs 1/14 (7%); grade (3/4) trombocytopenia 2/15 (13%) vs 1/14 (7%). Toxicities with concomitant RCT were low-moderate: urocystitis (26%) and enteritis (18%).

RESPONSE

microscopically complete TURB was obtained in 20 p (69%), but not in 9 p (31%) (7 microscopic, and 2 macroscopic residual tumor). We found a complete histologic response after induction RCT in 25 p (86%). After a median follow-up of 69.4 months (m) (range: 8-97.7), there were 8 deaths, with a overall survival of 72%. Furthermore 14 of 29 p (48%) were alive with intact bladder, and median survival time with intact bladder was 63.6 m (50.1-77.2); were predictive of best outcome T2 stage vs T3 (p < 0.0001), and complete histologic resection in initial TURB vs residual tumor (p = 0.0004).

CONCLUSIONS

Combined treatment provide high response rates and can be offered as an alternative option to radical cystectomy in selected patients with TCC. Patients with T2 stage and complete histologic resection in initial TURB had the best outcome.

Long-term outcome of acute tubular necrosis: a contribution to its natural history

As long-term outcome studies of acute renal failure (ARF) are scarce and non-homogeneous, we studied 187 consecutive acute tubular necrosis (ATN) patients without previous nephropathies, discharged alive from our hospital between October 77 and December 92 and followed-up until December 99 (range 7-22 years; median 7.2). Variables were analyzed at the time of the acute episode and during follow-up. In 2000-2001 a clinical evaluation was made in 58 of the 82 patients still alive. Ten patients were lost to follow-up and 95 died. In 59% death was related with the disease present when the ATN developed. Kaplan-Meir survival curve showed 89, 67, 50, and 40% at 1, 5, 10, and 15 years, respectively, after discharge. Survival curves were significantly better (log-rank P<0.001) among the youngest, those surviving a polytrauma, those without comorbidity and surprisingly those treated in intensive care units. The proportional Cox model showed that age (hazard ratio (HR) 1.04 per year of age; P=0.000), presence of comorbid factors (HR 4.29; P=0.006), surgical admission (HR 0.45; P=0.000), and male sex (HR 1.72; P=0.020) were the variables associated with long-term follow-up. In the evaluated patients renal function was normal in 81%. Long-term outcome after ARF depends on absence of co-morbid factors, cause of initial admission and age. Although the late mortality rate is high and related with the original disease, renal function is adequate in most patients.

The malignant potential of a succinate dehydrogenase subunit B germline mutation

Familial catecholamine secreting tumors have been associated with multiple endocrine neoplasia type 2, Von Hippel-Lindau disease and neurofibromatosis type 1. In the last years, mutations of genes encoding subunits B, C and D of the succinate dehydrogenase have been discovered as other causes of pheochromocytomas and paragangliomas. We diagnosed a malignant retroperitoneal paraganglioma in a 64-yr-old man with bone metastasis in 2001. Two years later a retroperitoneal benign paraganglioma was found and resected in his 32-yr-old daughter. Thus we diagnosed in this family a paraganglioma syndrome. We performed molecular genetic analyses of the genes SDHB, SDHC, and SDHD. We detected in the SDHB gene the mutation SDHB c. 558-3 C> G affecting the splice site of exon 5. In a second daughter the mutation was also detected, thorough clinical investigation revealed normal results. We conclude that the SDHB mutation predisposes to abdominal extra-adrenal and potential malignant pheochromocytoma with incomplete penetrance.

[Influence of the polymorphism 03826 A --> G in the UCP1 gene on the components of metabolic syndrome]

BACKGROUND

The uncoupling protein UCP1 has been related to the development and/or maintenance of obesity through its involvement in regulating energy balance. The role of this mitochondrial protein in humans is uncertain due to the scarce presence of the brown adipose tissue in the adult individual. The polymorphism -3826 A/G of the UCP1 alone or in conjunction with the mutation Trp64Arg of the adrenergic receptor b3 has been associated with obesity, diabetes mellitus and related diseases although with contradictory results. With the aim of determining the influence of polymorphism -3826 A/G of the UCP1 on the classical components of the metabolic syndrome in our population, we studied 159 obese individuals and 154 of normal weight, with a study design of cases and controls. In all of them Body Mass Index (BMI), hip/waist index, % of body fat, arterial tension (AT), lipidic profile, leptine, basal glucemia and basal insulinemia were determined. Similarly, the presence of the above mentioned mutation of the UCPI gene was analysed.

RESULTS

Significant differences were obtained in all of the variables studied between obese (cases) and normal weight (controls). Within the obese group, polymorphism -3826 A/G of the UCP1 gene (n=53) was associated with a greater BMI (p=0.03), greater percentage of body fat (p=0.04) and higher AT both systolic (p=0.009) and diastolic (p=0.02). There were no statistically significant differences in any of the other indices evaluated.

CONCLUSION

The fundamental factor that influences the components of the metabolic syndrome is obesity. However, the polymorphism -3826 A/G of the UCP1 gene is associated with a greater degree of obesity and very high figures of AT.

[Secondary osteoporosis]

Secondary osteoporosis is caused by pathologies or medications, differing from the bone loss explainable by the post-menopausal stage or by ageing. The possible pathologies that can condition the loss of bone mass are very varied: endocrinological, digestive, genetic, haematological, rheumatic, post-transplant, pharmacological and a wide miscellaneous group. This article essentially reviews the endocrinological causes, with special emphasis on the more controversial aspects, followed by a clinical approach for the systematic diagnosis of these pathologies, which are frequent in cases initially labelled as primary osteoporosis

Hyperfractionated chemoradiation with carbogen breathing, with or without erythropoietin: a stepwise developed treatment schedule for advanced head-and-neck cancer

PURPOSE

To investigate the influence of carbogen breathing on chemoradiation and the effects of erythropoietin on transfusions.

METHODS AND MATERIALS

From March 1996 to April 2000, 42 (4 Stage III and 38 Stage IV) patients with head and neck cancer were treated with a twice-a-day hyperfractionated schedule. Each fraction consisted of 5 mg/m(2) of carboplatin plus 115 cGy with carbogen breathing. Treatment was given 5 days per week up to total doses of 350 mg/m(2) of carboplatin plus 8050 cGy in 7 weeks. Anemia was treated either by transfusion or by erythropoietin.

RESULTS

Forty-one patients tolerated the treatment as scheduled. All patients tolerated the planned radiation dose. Five transfusions were given in the first group, but no transfusion was needed in the erythropoietin group. Local toxicities remained at the level expected with irradiation alone. Chemotherapy toxicity was moderate. Forty-two complete responses were achieved. At two years actuarial local control, cause-specific survival and overall survival are respectively 85%, 69%, and 68%. At four years estimated probabilities of local control, cause-specific survival and overall survival are also 85%, 69%, and 68%.

CONCLUSIONS

These results compare favorably with those of most reported studies. The addition of carbogen breathing appears to improve the results of chemoradiation alone. Erythropoietin therapy avoided transfusions.

Chemotherapy as a part of each treatment fraction in a twice-a-day hyperfractionated schedule: a new chemoradiotherapy approach for advanced head and neck cancer

BACKGROUND

Using chemotherapy as a part of each treatment fraction remains unexplored. This study integrates the concomitant administration of carboplatin with hyperfractionated irradiation by optimizing chemopotentiation through carboplatin administration with each irradiation fraction.

METHODS

From February 1993 to August 1996, 52 patients with advanced head and neck cancer were treated on a twice-a-day chemoradiotherapy schedule. Each fraction consisted of 115 cGy preceded by 5 mg/m2 of carboplatin. Treatment was given 5 days a week up to total doses of 350 mg/m2 of carboplatin + 8050 cGy in 7 weeks.

RESULTS

All (100%) of patients tolerated the treatment (83% as scheduled). Acute and late toxicities were moderate. Rates of 96% complete response (CR) and 4% partial response (PR) were achieved. At 52 months, local control and cause-specific survival rates are 72% and 59%, respectively. Nodal control rate is 95%.

CONCLUSION

These results show potential for improvement upon hyperfractionated radiotherapy alone and compare favorably with those of most reported trials.

An immunohistochemical study of UV-induced skin lesions in actinic prurigo. Resistance of langerhans cells to UV light

Actinic prurigo is an inflammatory disease of the skin that appears to be mediated by an abnormal immune response. Cell adhesion molecules play a key role in the induction of the immune response as well as in the pathogenesis of inflammation. We investigated the expression of cell adhesion and activation molecules, as well as the density of Langerhans cells in skin from patients with actinic prurigo. Skin biopsies from ultraviolet light-induced lesions, and non-irradiated areas from 10 actinic prurigo patients were studied; in addition, several spontaneous skin lesions were studied. Skin biopsies from normal individuals were used as controls. The expression of ICAM-1, ICAM-3, LFA-3, CD2, LFA-1, VLA-4, CD1a, VCAM-1, CD69, and activated b1 integrins were assessed by immunostaining. An increased expression of LFA-1, LFA-2, ICAM-3, VLA-4, and activated b1 integrins was observed in the cell infiltrate of actinic prurigo lesions and an up-regulated expression of ICAM-1 was detected in keratinocytes from these specimens. Interestingly, the number of Langerhans cells (CD1a + ) in actinic prurigo skin was not significantly affected by ultraviolet irradiation, a phenomenon that was not observed in normal controls. The increased expression of adhesion molecules in the cell infiltrate of actinic prurigo, indicates that these cells are activated and suggests that they are involved in the skin damage seen in these patients. The resistance of Langerhans cells from patients with actinic prurigo to ultraviolet light may have an important role in the pathogenesis of this condition. The involvement of keratinocytes in the pathogenesis of actinic prurigo is suggested by the expression of ICAM-1 on these cells.

Late complication of a Greenfield filter associating caudal migration and perforation of the abdominal aorta by a ruptured strut

We report the case of a 67-year-old woman who was admitted for surgical removal of a Greenfield filter that had been inserted 7 years before because of recurrent deep vein thrombosis associated with pulmonary embolism. This complication appeared on a plain abdominal radiogram that showed a 7 cm distal migration of the filter, a 30-degree angulation, and rupture of a strut at the level of the hub. Computed tomography, aortography, and ascending cavography demonstrated that the inferior vena cava was perforated by the struts and that the ruptured strut had penetrated the infrarenal aorta. As demonstrated by scanning electron microscopy, the fracture was due to a structural defect of the strut at its insertion point within the hub, with no sign of corrosion. Energy-dispersive radiography analysis failed to demonstrate impurity in the metal composition.

[Pre S1 antigen in different forms of hepatitis B virus infection]

Pre S1 antigen was measured using an ELISA technique in patients with different forms of hepatitis B virus infection. It was detected in 10 of 19 patients with acute hepatitis B (53%), 12 of 15 chronic hepatitis B virus carriers (80%), 9 of 11 patients with chronic hepatitis B (82%) and 3 of 4 patients with hepatoma and positive markers of hepatitis B virus infection. Pre S1 remained positive beyond 150 days in two patients with acute hepatitis that evolved to chronicity. Among subjects with chronic hepatitis B that received interferon, pre S1 antigen negativized only in the patient that had a complete response. Pre S1 detection is an index of hepatitis B virus replication and its persistence determines chronicity. Its negativization after antiviral therapy should have a predictive value.

Age influence on mononuclear phagocyte system Fc-receptor function in poststreptococcal nephritis

The Fc-receptor function of the mononuclear phagocyte system (MPS) was examined in 41 children and adult patients, by measuring the clearance of IgG-sensitized, 51Cr-labeled erythrocytes. The Fc-receptor-mediated clearance observed in patients (mean +/- SE) was not significantly different as compared to the control group of similar age distribution. However, the immune clearance time was significantly age-correlated in both groups (acute poststreptococcal glomerulonephritis, APSGN, r = 0.39, p less than 0.05; control r = 0.63, p less than 0.01). The magnitude of the Fc-specific immune clearance and the serum creatinine were also significantly correlated (r = 0.59; p less than 0.01). Circulating immune complexes (as measured by the C1q and conglutinin ELISA) did not correlate with immune clearance, which remained stable in longitudinal studies. Age-related changes in MPS Fc-receptor function could explain, at least in part, prognostic differences between children and adult patients with APSGN.

[B-DR (HLA) linkage imbalance and transplants in Chile: a preliminary report]

Linkage imbalance for the B and DR loci (HLA) was found in a Chilean sample of families where a member had been proposed for transplantation. The B7-DR2 and B14-DR1 haplotypes were significantly more frequent than expected. Most associations were those found in Caucasian populations.