Requirements for dose calculation on an active scanned proton beamline for small, shallow fields

INTRODUCTION

A growing interest in using proton pencil beam scanning in combination with collimators for the treatment of small, shallow targets, such as ocular melanoma or pre-clinical research emerged recently. This study aims at demonstrating that the dose of a synchrotron-based PBS system with a dedicated small, shallow field nozzle can be accurately predicted by a commercial treatment planning system (TPS) following appropriate tuning of both, nozzle and TPS.

MATERIALS

A removable extension to the clinical nozzle was developed to modify the beam shape passively. Five circular apertures with diameters between 5 to 34mm, mounted 72cm downstream of a range shifter were used. For each collimator treatment plans with spread-out Bragg peaks (SOBP) with a modulation of 3 to 30mm were measured and calculated with GATE/Geant4 and the research TPS RayStation (RS11B-R). The dose grid, multiple coulomb scattering and block discretization resolution were varied to find the optimal balance between accuracy and performance.

RESULTS

For SOBPs deeper than 10mm, the dose in the target agreed within 1% between RS11B-R, GATE/Geant4 and measurements for aperture diameters between 8 to 34mm, but deviated up to 5% for smaller apertures. A plastic taper was introduced reducing scatter contributions to the patient (from the pipe) and improving the dose calculation accuracy of the TPS to a 5% level in the entrance region for large apertures.

CONCLUSION

The commercial TPS and GATE/Geant4 can accurately calculate the dose for shallow, small proton fields using a collimator and pencil beam scanning.

Technical Note: Impact of Beam Properties for Uveal Melanoma Proton Therapy - An In-Silico Planning Study

PURPOSE

To evaluate the impact of beam quality in terms of distal fall-off (DFO, 90% to 10%) and lateral penumbra (LP, 80% to 20%) of single beam ocular proton treatment (OPT) and to derive resulting ideal requirements for future systems.

METHODS

Nine different beam models with DFO varying between 1 mm and 4 mm and LP between 1 mm and 4 mm were created. Beam models were incorporated into the RayStation with RayOcular TPS version 10 B (RaySearch Laboratories, Sweden). Each beam model was applied for eight typical clinical cases, covering different sizes and locations of uveal melanoma. Plans with and without an additional wedge were created, resulting in 117 plans with a total prescribed median dose of 60 Gy(RBE) to the CTV. Treatment plans were analyzed in terms of V20-V80 penumbra volume, D1 (dose to 1% of the volume) for optic disc and macula, optic nerve V30 (volume receiving 30 Gy(RBE), i.e. 50% of prescription), as well as average dose to lens and ciliary body. A LP dependent aperture margin was based on estimated uncertainties, ranging from 1.7 mm to 4.0 mm.

RESULTS

V20-V80 showed a strong influence by LP, while DFO was less relevant. The optic disc D1 reached an extra dose of up to 3000 cGy(RBE), comparing the defined technical limit of DFO = LP = 1 mm with DFO = 3 mm/ LP = 4 mm. The latter may result from a pencil-beam scanning (PBS) system with static apertures. Plans employing a wedge showed an improvement for organs at risk (OAR) sparing.

CONCLUSION

Plan quality is strongly influenced by initial beam parameters. The impact of LP is more pronounced when compared to DFO. The latter becomes important in the treatment of posterior tumors near the macula, optic disc or optic nerve. The plan quality achieved by dedicated OPT nozzles in single- or double-scattering design might not be achievable with modified PBS systems. This article is protected by copyright. All rights reserved.

Assessing immune organs on 18F-FDG PET/CT imaging for therapy monitoring of immune checkpoint inhibitors: inter-observer variability, prognostic value and evolution during the treatment course of melanoma patients

BACKGROUND

Immune checkpoint inhibitors (ICIs) have significantly improved survival in advanced melanoma. There is a need for robust biomarkers to identify patients who do not respond. We analysed 14 baseline ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) metrics and their evolution to assess their correlation with patient outcome, compared with 7 established biological markers and 7 clinical variables.

METHODS

We conducted a retrospective monocentric observational study of 29 patients with advanced melanoma who underwent baseline ¹⁸F-FDG PET/CT, followed by an early monitoring PET/CT (iPET) scan after 1 month of treatment and follow-up studies at 3rd (M3PET) and 6th month (M6PET). ¹⁸F-FDG uptake in immune organs (spleen, bone marrow, ileocecal valve) and derived spleen-to-liver (SLR) and bone-to-liver (BLR) ratios were reviewed by two PET readers for reproducibility analysis purposes including 14 PET variables. The most reproducible indexes were used for evaluation as predictors of overall survival (OS) in comparison with PET response using imPERCIST5, whole-body metabolic active tumour volume (WB-MATV) and biological parameters (lactate dehydrogenases (LDH), reactive protein c (CRP), white blood count (WBC), absolute lymphocyte count (ALC), neutrophil to lymphocyte ratio (NLR) and derived neutrophils to lymphocyte ratio).

RESULTS

Strong reproducibility's (intraclass coefficients of correlation (ICC) > 0.90) were observed for spleen anterior SUV_peak, spleen MV, spleen TLG, spleen length and BLR_mean. ICC for SLR_mean and ileocecal SUV_mean were 0.86 and 0.65, respectively. In the 1-year OS 1 group, SLR_mean tended to increase at each time point to reach a significant difference at M6-PET (p = 0.019). The same trends were observed with spleen SUV_peak anterior and spleen length. In the 1-year OS 0 group, a significative increase of spleen length was found at iPET, as compared with baseline PET (p = 0.014) and M3-PET (p = 0.0239). Univariable Kaplan-Meier survival analysis found that i%var spleen length, M3%var SLR_mean, baseline LDH, i%var NLR and response at M6PET were all predictors of 1-year OS.

CONCLUSIONS

SLR_mean is recommended as a prognosticator in melanoma patients under immunotherapy: its increase greater than 25% at 3 months, compared with baseline, was associated with poor outcome after ICIs.

Screening vs. non-screening detected colorectal cancer: Differences in pre-therapeutic work up and treatment

Objectives To compare preoperative staging, multidisciplinary team-assessment, and treatment in patients with screening detected and non-screening detected colorectal cancer. Methods Data on patient and tumour characteristics, staging, multidisciplinary team-assessment and treatment in patients with screening and non-screening detected colorectal cancer from 2008 to 2012 were collected from the Stockholm-Gotland screening register and the Swedish Colorectal Cancer Registry. Results The screening group had a higher proportion of stage I disease (41 vs. 15%; p < 0.001), a more complete staging of primary tumour and metastases and were more frequently multidisciplinary team-assessed than the non-screening group ( p < 0.001). In both groups, patients with endoscopically resected cancers were less completely staged and multidisciplinary team-assessed than patients with surgically resected cancers ( p < 0.001). No statistically significant differences were observed between the screening and non-screening groups in the use of neoadjuvant treatment in rectal cancer (68 vs.76%), surgical treatment with local excision techniques in stage I rectal cancer (6 vs. 9%) or adjuvant chemotherapy in stages II and III disease (46 vs. 52%). Emergency interventions for colorectal cancer occurred in 4% of screening participants vs. 11% of non-compliers. Conclusions Screening detected cancer patients were staged and multidisciplinary team assessed more extensively than patients with non-screening detected cancers. Staging and multidisciplinary team assessment prior to endoscopic resection was less complete compared with surgical resection. Extensive surgical and (neo)adjuvant treatment was given in stage I disease. Participation in screening reduced the risk of emergency surgery for colorectal cancer.

Relation of intraoperative temperature to postoperative mortality in open colon surgery--an analysis of two randomized controlled trials

INTRODUCTION

The open surgical wound is exposed to cold and dry ambient air resulting in heat loss mainly through radiation and convection. This cools the wound and promotes local vasoconstriction and hypoxia. Carbon dioxide (CO2) and water vapor are greenhouse gases with a warming effect. The aim was to evaluate if warm humidified CO2 insufflated in surgical wound can affect long-term overall mortality

METHODS

This is a retrospective study of two clinical trials, where patients were randomized to warm humidified CO2 (n = 80) or not (n = 78). All patients underwent elective major open colon surgery. Patients in the treatment group received insufflation of warm humidified CO2 into the open wound cavity via a gas diffuser to create a local atmosphere of 100% CO2. Temperature in the wound cavity was measured with a heat-sensitive infrared camera. Core temperature was measured at the tympanic membrane. Median follow-up was 70.9 months.

RESULTS

A multivariate analysis adjusted for age (p = 0.001) and cancer (p = 0.165) showed that the larger the temperature difference between final core temperature and wound edge temperature, the lower the overall survival rate (p = 0.050). Patients receiving insufflation of warm humidified CO2 had a tendency to a better overall survival compared with control patients (p = 0.508). End-of-operation wound edge temperature was negatively associated with mortality (OR = 0.80, 95% CI = 0.68-0.95, p = 0.011), whereas mortality was positively associated with age (10-year increase, OR = 1.78, 95% CI = 1.37-2.33, p < 0.001) and cancer (OR = 8.1, 95% CI = 1.95-33.7, p = 0.004).

CONCLUSIONS

A small end-of-operation temperature difference between final core and wound edge temperature was positively associated with patient survival in open colon surgery.

Consulting for substance abuse: mental disorders among adolescents and their parents

Studies conducted outside of Scandinavia indicate that most adolescents with substance misuse problems suffer from co-morbid mental disorders. The present study assessed the mental health of adolescents seeking help for substance misuse problems in a large Swedish city. Parents' mental health was also examined. The sample included 97 girls with their 90 mothers and 52 fathers, and 81 boys with their 72 mothers and 37 fathers. The adolescents completed a diagnostic interview, either the Kiddie-SADs or the Structured Clinical Interview for DSM-IV (SCID) depending on their age. Their parents underwent diagnostic interviews with the SCID. Ninety per cent of the girls and 81% of the boys met criteria for at least one disorder other than substance misuse, and on average, they suffered from three other disorders, most of which had onset before substance misuse began. Almost 80% of the mothers and 67% of the fathers met criteria for at least one mental disorder other than alcohol and drug-related disorders. The findings concur with those reported from studies conducted in North America. The results suggest that in Sweden mental disorders are not being identified and effectively treated among some children and young adolescents who subsequently abuse alcohol and/or illicit drugs. Adolescents who consult for substance abuse problems require assessments and treatment by mental health professionals.

Randomized clinical trial of the costs of open and laparoscopic surgery for colonic cancer

BACKGROUND

There has been no randomized clinical trial of the costs of laparoscopic colonic resection (LCR) compared with those of open colonic resection (OCR) in the treatment of colonic cancer.

METHODS

A subset of Swedish patients included in the Colon Cancer Open Or Laparoscopic Resection (COLOR) trial was included in a prospective cost analysis; costs were calculated up to 12 weeks after surgery. All relevant costs to society were included. No effects of the procedures, such as quality of life or survival, were taken into account.

RESULTS

Two hundred and ten patients were included in the primary analysis, 98 of whom had LCR and 112 OCR. Total costs to society did not differ significantly between groups (difference in means for LCR versus OCR euro1846; P = 0.104). The cost of operation was significantly higher for LCR than for OCR (difference in means euro1171; P < 0.001), as was the cost of the first admission (difference in means euro1556; P = 0.015) and the total cost to the healthcare system (difference in means euro2244; P = 0.018).

CONCLUSION

Within 12 weeks of surgery for colonic cancer, there was no difference in total costs to society incurred by LCR and OCR. The LCR procedure, however, was more costly to the healthcare system.

Comparison of 0.5% intrathecal bupivacaine with 0.5% intrathecal ropivacaine in the treatment of refractory cancer and noncancer pain conditions: results from a prospective, crossover, double-blind, randomized study

BACKGROUND AND OBJECTIVES

Intrathecal (IT) administration of bupivacaine (BUP) for treatment of "refractory" pain has sometimes been associated with unacceptable side effects. This study was undertaken to determine if IT-ropivacaine (ROP) can reduce the rate and intensity of these side effects e.g., urinary retention, paresthesia, and particularly, paresis with gait impairment. A prospective, crossover, double-blind, randomized study.

METHODS

Twenty-one patients were enrolled, 9 dropped out of the study, and data were analyzed from 12 patients. Patients were treated by insertion of IT tunneled nylon catheters, continuous infusion of 0.5% ROP followed by 0.5% BUP or 0.5% BUP followed by 0.5% ROP solutions from an external electronic pump. Each local anesthetic was infused for 7 days, and their order of infusion randomized. The comparative efficacy of the ROP and BUP IT infusions was assessed from the daily doses of IT ROP and IT BUP, oral and parenteral opioids, and daily scores of nonopioid analgetic and sedative drug consumption. Self-reported pain intensity (visual analogue scale [VAS] mean scores) and scores of Bromage relaxation, ambulation, nocturnal sleep pattern, rates of side-effects attributable to the IT drugs, the patients' assessment of the IT ROP v the IT BUP periods of the trial, and the comparative daily cost of IT ROP v IT BUP were recorded.

RESULTS

The daily doses of the local anesthetics used were 23% higher for ROP than for BUP. Further, the daily cost was approximately equals 3 times higher for ROP than for BUP. No other significant differences between IT ROP and IT BUP were found.

CONCLUSION

The results of this study do not support the hypothesis that IT infusion of 0.5% ROP has advantages over IT infusion of 0.5% BUP when administered for relief of "refractory" pain.

EDTA chelation therapy in the treatment of vascular disease

Ethylenediamine tetraacetic acid (EDTA) chelation therapy has been used for decades for the treatment of vascular disease, alone or in combination with other treatments. This article includes a historic review of the research literature, current evidence of effectiveness, potential mechanisms of action of EDTA, and some brief case reports. The authors conclude that EDTA chelation therapy is a valuable therapeutic option for vascular disease, either alone or in conjunction with standard treatment protocols.

Continuous intracisternal and high cervical intrathecal bupivacaine analgesia in refractory head and neck pain

BACKGROUND

The upper cervical component of the spinomesencephalic tract and cranial nerves V, VII (nervus intermedius), IX, and X are involved in mechanisms of acute and chronic pain from head and neck structures. To date there is no reliable method for relief of refractory pain (i.e., pain that cannot be relieved by conventional pharmacologic therapies) from these structures. Therefore, we explored continuous intracisternal infusion of bupivacaine for the treatment of refractory pain of the head and neck.

METHODS

Intracisternal catheters were inserted in 13 adults with refractory nonmalignant (n = 4) and malignant (n = 9) pain from the head, face, mouth, neck, and upper extremities; 0.5% plain bupivacaine was infused continuously at rates of 1-7 (median 1.5) mg/h with optional bolus doses of 0.5-2.0 mg 4-2 times/h. The efficacy was assessed from pain relief (daily VAS(max), VAS(min), and VAS(mean) scores 0-10), daily doses of intracisternal bupivacaine and total opioid (expressed as mg parenteral morphine-eq), amount of nocturnal sleep, and rates of adverse effects.

RESULTS

The 13 patients were treated for 3-182 days (median 37, total 712 days), 3 patients being treated at home for 10-112 days (median 88, total 210 days). In one patient, the efficacy of the treatment could not be estimated because of advanced senility. Eleven of the remaining 12 patients obtained acceptable pain relief with daily doses of intracisternal bupivacaine ranging from 20 to 118 mg (median 37 mg): VAS(mean) scores decreased from 7 to 2, mean pain relief increased for 30% to 80%, total opioid daily dose decreased from 53 to 36 mg parenteral morphine-eq, and nocturnal sleep increased from 2 to >6h (all figures are median values). Speech, eating, walking, and natural functions were generally not affected. Side effects such as tiredness and malaise, somnolence and sleep, feeling of coldness in the neck and skull base, transient post-spinal puncture headache, paresthesias, hoarseness, dysphagia, transient paresis of the upper/lower extremities, episodic miosis and conjunctival hyperemia, and transient orthostatic arterial hypotension were each observed in one or two patients. No patient presented clinical evidence of phrenic nerve paralysis. There was no nausea or vomiting. No persistent neurologic deficit or death could be attributed to the intracisternal pain treatment.

CONCLUSIONS

Continuous intracisternal infusion of bupivacaine may be a useful method in exceptional, well selected patients with refractory pain from the head and neck structures. Further studies are necessary to establish the indications and the safety of the method.

Physical mapping of the NF2/meningioma region on human chromosome 22q12

Loss of genetic information from chromosome 22 has been implicated in the development of neurofibromatosis type 2, meningioma, and several other neoplasia. Molecular studies indicate that genes within chromosomal band 22q12 may be involved in tumorigenesis. We have mapped 29 loci into 16 groups in this region, using pulsed-field gel electrophoresis, fluorescence in situ suppression hybridization, and somatic cell hybrid mapping. The region spans more than 5 Mb of genomic DNA and contains the genes for neurofibromatosis type 2 and meningioma. The order of loci presented here provides the framework for the fine mapping of this region using cosmids and yeast artificial chromosomes, and it facilitates the speedy cloning of novel genes from 22q12.

Intragenic reorganization of RB1 in a complex (4;13) rearrangement demonstrated by FISH

Reciprocal chromosome translocations with no apparent loss of material are the most common de novo structural rearrangements in man. The large majority of these cases have been characterized cytogenetically but very few have been investigated at the molecular level. Using fluorescence in situ hybridization (FISH) we have studied the organization of the tumor suppressor gene RB1 in a patient with retinoblastoma and a rearrangement between chromosomes 4 and 13. In addition to the hybridization signal on the normal chromosome 13, three distinct sites of hybridization of RB1 probes on the translocated chromosomes were detected. These findings show that a complex rearrangement occurred involving at least three breaks on chromosome 13, two of them in the RB1 gene. This also demonstrates that FISH, which offers resolution between that of fine molecular methods and classical cytogenetics, is a valuable tool for investigating organization of sequences at breakpoints of chromosomal rearrangements.

A constitutional mutation within the retinoblastoma gene detected by PFGE

Retinoblastoma may be caused by constitutional mutations in the retinoblastoma gene which segregates as an autosomal dominant inherited predisposition for developing retinoblastoma tumours. Since 75% of these cases are new mutations, there is a need for methods to identify carriers of such germ-line mutations, so that informed genetic counselling is available to patients and close relatives. We have used pulsed-field gel electrophoresis in screening 20 unrelated cases with bilateral retinoblastoma. One constitutional mutation could be detected, and was found to be caused by a balanced chromosome (4;13) translocation with the breakpoint within intron 17 of the retinoblastoma gene.

Isolation and mapping of polymorphic cosmid clones used for sublocalization of the multiple endocrine neoplasia type 1 (MEN1) locus

Multiple endocrine neoplasia type 1 (MEN1) is characterized by neoplasia of the parathyroids, the pancreas, and the pituitary. Tumorigenesis involves unmasking of a recessive mutation at the MEN1 locus, which has been mapped to the centromeric part of chromosomal region 11q. In order to localize the MEN1 gene further and to make its isolation possible, a number of new markers were isolated. Two radiation-reduced somatic cell hybrids were identified that only contained markers close to and flanking the MEN1 region. DNA from these hybrids was used for the construction of a cosmid library, and clones containing human inserts were isolated. In addition, cosmid clones were isolated for locus expansion of 7 other markers that were mapped to the 11q12-13.2 region. The 33 newly isolated clones together with 25 previously published markers from this region were analyzed in a panel of radiation-reduced somatic cell hybrids. From the hybridization pattern, the region was divided into 11 parts. New restriction fragment length polymorphisms were identified in 7 of the newly isolated cosmid clones and in one plasmid. These were then used to sublocalize meiotic cross-overs more precisely in two MEN1 families, thus refining the mapping of the disease gene.

Contiguous localization of the genes encoding human insulin-like growth factor binding proteins 1(IGBP1) and 3(IGBP3) on chromosome 7

In extracellular fluids the insulin-like growth factors (IGFs) are bound to specific binding proteins (IGBPs). The genes for two members of this protein family have been mapped, the IGBP1 gene to human chromosomal region 7p14-p12 and the IGBP2 gene to region 2q33-q34. In this study, somatic cell hybrid analysis indicated that IGBP3 is also located on chromosome 7. Pulsed-field gel electrophoresis was used to demonstrate the close physical linkage between IGBP1 and IGBP3. Overlapping cosmid clones encompassing these genes were isolated, and restriction endonuclease mapping showed that the genes are arranged in a tail-to-tail fashion separated by 20 kb of DNA. Further characterization of the IGBP1 DNA sequence disclosed a duplication of the intron 3-exon 4 junction within the third intron. In addition, we report RFLPs for ApaLI and TaqI in the IGBP1 locus.

Sublocalization of the multiple endocrine neoplasia type 1 gene

Tumorigenesis in multiple endocrine neoplasia type 1 (MEN 1) involves the unmasking of a recessive mutation at the MEN 1 locus which has been mapped to chromosomal region 11q11-13. By analyzing 58 DNA markers on a panel of radiation-reduced somatic cell hybrids, the region encompassing the MEN 1 gene was divided into nine subregions. Pulsed field gel electrophoresis analysis of markers within subgroups showed that the recombination rate around the MEN 1 locus is high. Combined linkage analysis in MEN 1 families and deletion mapping in MEN 1-related tumors suggest the MEN 1 gene is located centromeric to D11S807 and telomeric to PYGM.

Detailed physical map of human chromosomal region 11q12-13 shows high meiotic recombination rate around the MEN1 locus

We have constructed a physical map of the region q12-13 on chromosome 11 by combining data generated from a panel of radiation-reduced somatic cell hybrids and pulsed-field gel electrophoresis (PFGE). Twenty different genetic markers have been sublocalized and ordered within this region and a total of 8.0 megabases has been mapped in detail using rare-cutting restriction endonucleases and PFGE. In two instances, the long-range restriction PFGE map spans the total distance between pairs of loci that have been previously mapped by genetic linkage in reference families. Comparison of this physical map with the available linkage map indicates a great variation in the recombination frequency over the region. The recombination rate is higher than expected, particularly for markers flanking the MEN1 region. Thus, for the closest pair of linked markers on the centromeric side, one centimorgan corresponds to approximately 300 kilobases, and for markers on the telomeric side, one centimorgan corresponds to approximately 350-600 kilobases.

[Heterotopic pancreatic cyst of the stomach wall]

A 28 year old female was admitted to the hospital with dolorous postprandial swelling of the left upper epigastrium, occurring since the recent death of her husband. After an asymptomatic interval of eight years pains similar to biliary colics occurred increasing in duration, intensity and frequency during the following year. Sonography and computer-tomography indicated a pseudocyst of the pancreascauda adjacent to the left lobe of the liver, spleen and gastric wall. Laparotomy revealed the diagnosis of a heterotopic cyst of the pancreas of fist-size localized intramurally in the gastric corpus which was totally resected. Histologically a granulomatous partially transformed cyst in a heterotopic pancreas was identified. The patient became symptom-free after the operation.

Constitutional deletions predisposing to retinoblastoma

Patients with the heritable form of retinoblastoma carry a constitutional mutation in the retinoblastoma locus in heterozygous form. The majority of such cases are the result of new mutations, which may be inherited by their offspring. We have identified such constitutional mutations within the retinoblastoma locus in 3 out of 66 investigated unrelated gene carriers, using Southern blot analysis and Rb-gene cDNA-probes. The identified mutations were found to be located in different regions of the gene. These analyses may be used to identify or exclude close relatives at risk for the disease. In 2 of the 3 cases, the identified aberrations were used for informed genetic counselling of relatives.

Prediction of the risk of hereditary retinoblastoma, using DNA polymorphisms within the retinoblastoma gene

Using molecular cloning, we earlier isolated the "retinoblastoma gene"; mutations or deletions at this locus are associated with the hereditary predisposition to some human cancers, especially retinoblastoma and osteosarcoma. To develop diagnostic tests for such a predisposition, we identified restriction-fragment-length polymorphisms (RFLPs) within the retinoblastoma gene and tested their usefulness in predicting the risk of cancer in 20 families with members who had hereditary retinoblastoma. We were able to make predictions in 19 of the 20 kindreds. In 18 kindreds, we demonstrated a consistent association of marker RFLPs with the mutation predisposing to retinoblastoma. In the 19th kindred, there may be a lack of cosegregation of the DNA polymorphisms within the gene and the site of the mutation predisposing to retinoblastoma. However, there is uncertainty about the clinical diagnosis of the retinal lesion in a key member of this kindred; if the lesion is not a retinoblastoma, there is no discrepancy between the DNA polymorphisms and the retinoblastoma trait. We conclude that it is feasible and clinically useful to use these DNA polymorphisms to determine the risk of cancer.

Reproducibility of occlusal findings. A comparison between clinical and articulator analyses

The occlusal relationship may be examined clinically in the patient's mouth and on models mounted in an articulator. For the purpose of comparing the reproducibility of the two methods, the occlusion of 10 subjects was analyzed twice with at least 1 week's interval. Certain variations were demonstrated with both methods. Overall reproducibility of tooth contact was observed more frequently in the articulator than in the mouth. The methods showed an equal degree of consistency for measurements of slide in centric. However, when subjects were classified by the extent of occlusal interference, the findings of the clinical analysis seemed to be more reproducible than those recorded by means of the articulator.

Quantitative determination of platelet surface alloantigens using a monoclonal probe

A monoclonal antibody with specificity for the Fc portion of IgG was used to determine the number of IgG alloantibody molecules bound at saturation to alloantigens of the PlA1 and HLA systems on normal human platelets. In preliminary studies, it was found that the number of cell-bound IgG molecules recognized by this probe correlates well with the number measured by electroimmunoassay, an independent measure of alloantibody binding. PlA1-positive platelets could be divided into two groups binding 34,000-43,000 or 19,000-24,000 alloantibody molecules. Family studies and studies with a cytolytic assay showed that the former group is homozygous and the latter heterozygous for PlA1. Because the number of glycoprotein IIIa (GPIIIa) molecules carrying the PlA1 determinant on the surface of normal platelets is thought to be about 40,000, these findings suggest that each GPIIIa molecule carries one PlA1 determinant. The number of class I HLA molecules expressed on normal platelets was considerably smaller than the number of PlA1 determinants, ranging from 4400 to 10,000 (HLA-A2), 870 to 8400 (Bw4), and 1300 to 5800 (Bw6). Preliminary analysis indicates that stronger or weaker expression of Bw4 and of Bw6 correlates with certain "private" HLA-B determinants carried on the HLA-B molecule as found in previous studies using an indirect method to measure alloantigen density. These findings appear to explain why antibodies reactive with platelet-specific antigens such as PlA1 react more strongly with platelets than HLA-specific antibodies in most serologic tests. The weak expression of HLA determinants on platelets of some subjects may account for the less than perfect correlation between in vitro compatibility tests and post-transfusion platelet survivals observed in most studies.

Complement fixation by pemphigus antibody. I. In vitro fixation to organ and tissue culture skin

Although complement is often detected in the intercellular substance of pemphigus skin lesions, the ability of pemphigus antibodies to fix complement in vitro is controversial. The purpose of this study was to test in vitro complement fixation abilities of pemphigus antibodies further using organ and tissue culture methods. Epidermal cell monolayers from mouse tail were incubated with the purified IgG fraction of pemphigus serum followed by purified Clq. Binding of Clq, as well as IgG was demonstrated by immunofluorescence methods. When purified Clq was replaced with normal human serum as a complement source, positive C3 and C4 staining were also evident. When purified IgG of normal human serum was used in place of pemphigus IgG, similar immunofluorescence staining was not observed. Further evidence for complement fixation in vitro by pemphigus antibodies was obtained using organ cultures. Organ culture of normal human skin and monkey esophageal mucosa cultured in purified pemphigus IgG showed intercellular substance binding of IgG. No binding was observed when normal IgG was substituted for pemphigus IgG. Additional organ culture sections were then treated with complement (fresh normal human serum) and tested by in vitro complement staining. Fixation of Clq, C4, and C3 was noted in intercellular substance areas of organ cultured skin and mucosa incubated with pemphigus IgG but not those incubated with normal IgG. Prior treatment of pemphigus IgG organ cultured skin sections with unlabeled anti-C3, blocked positive C3 staining. These results suggest that some pemphigus antibodies are capable of activating complement in vitro.

[Experiences with active oral hygiene as a preventive treatment in patients with deciduous and mixed dentition]

The results of a study of active oral hygiene treatment in children between the ages of 4 and 12 was reported. It is absolutely imperative that both the children and the parents be highly motivated to carry out consistant oral hygiene. The basic level of oral hygiene for children can be considerably improved if the children are instructed in the appropiate technique for tooth brushing and allowed to practice; the children should be regularly checked by the dentist.

[Local anesthesia and beta receptor blockers in dentistry. (Study on an injectable combination of lidocaine and betadrenol)]

A double blind trial was undertaken to determine whether the addition of the beta-receptor blocker Betadrenol in two different doses to a lidocaine solution containing adrenaline could influence the exogenous and endogenous beta-adrenergic effects in the field of dental interventions under local anesthesia. It could be shown that already very small amounts of the beta-receptor blocker Betadrenol could suspend beta-adrenergic stimulation of the heart and so prevent unwanted circulatory reactions without side effects on the central nervous system.