Failure Mode and Effects Analysis for Treatment Workflow of a Novel Ring Gantry Linac

PURPOSE/OBJECTIVE(S)

A new ring gantry Linac machine combined with a PET ring is available in the market. It has 3 separate centers, one for laser, one for CT imaging and a 3rd for the Linac. As a first-generation machine of its kind, the workflow heavily depends on user-input. As example, it uses two separate coordinate systems, IEC for lasers and CT localization offsets and DICOM for treatment planning. The planner must manually convert between the two systems. We hypothesize that the unique design of the machine that is heavily dependent on users' input increases the potential of failure of treatment. The present work investigates failure modes for treatment delivery using the methodology of failure modes and effects analysis (FMEA) and proposes solutions to mitigate some of the failure modes (FMs).

MATERIALS/METHODS

A group of two radiation oncologists, two radiation therapists and three medical physicists was assembled. The process map for treatment delivery on the X1 was created and FMs were identified. Members independently graded each FM on 3 parameters, likelihood of occurrence, detectability of FM and level of severity on patient treatment. A grading scale of 1-5 was used with five representing the worst outcome in each parameter. Each member also identified the origin of each FM to be human, machine or clinical process. Mitigation solutions were proposed.

RESULTS

The process map of treatment delivery on X1 consists of six major processes and 24 sub-processes. A total of 27 FMs were identified, with many 19/27 (70%) caused by human errors and 7/27 (27%) caused by machine. From all responses, we tallied a median of 11 FMs (40%) that have both S≥ 4 and O or D ≥ 4. To further focus our analysis, we looked at the highest PRN scores from each member and found 7 FMs that were common. 1 FM was in "initiation of Treatment" sub-process and 6 FMs in "Treatment delivery" sub-process. Proposed solutions to these FMs were concerned with software upgrades. Examples are, allow changes in fractionation, allow dose tracking, auto calculation of couch position for various sub processes, allow DICOM image transfer and many more. The current clinical workflow that we adopted for these FMs either puts the burden on the user to confirm/verify parameters or the use of third-party software. In addition to these high-scoring FMs, we adopted changes in clinical workflow to mitigate other FMs, most of them through third-party software.

CONCLUSION

This study confirmed that the unique design and user-dependent machine environment, human failures are high accounting for 70% of FMs in treatment delivery alone. Our current workflow of the machine depends on direct user input to calculate/confirm certain parameters or the use of third-party software, which also depends on the user for proper completion of the task. Suggested solutions also included proposed improvement to the machine's software and user interface.

Practice patterns of pediatric total body irradiation techniques: A Children's Oncology Group survey

PURPOSE

The aim of this study was to examine current practice patterns in pediatric total body irradiation (TBI) techniques among xxx member institutions.

METHODS AND MATERIALS

Between Nov 2019 and Feb 2020 a questionnaire, containing 52 questions related to the technical aspects of TBI was sent to medical physicists at 152 xxx institutions. The questions were designed to obtain technical information on commonly used TBI treatment techniques. Another set of 9 questions related to the clinical management of patients undergoing TBI was sent to 152 xxx member radiation oncologists at the same institutions.

RESULTS

Twelve institutions were excluded because TBI was not performed in their institutions. A total of 88 physicists from 88 institutions (63% response rate) and 96 radiation oncologists from 96 institutions responded (69% response rate). The AP/PA technique was the most common (49 institutions - 56%); 44 institutions (50%) used the lateral technique and 14 institutions (16%) used volumetric modulated arc therapy (VMAT)/Tomotherapy. Mid-plane dose rates of 6-15 cGy/min were most commonly used. The most common specification for lung dose was the mid lung dose for both AP/PA (71%) and lateral (63%) techniques. All physician responders agreed with the need to refine current TBI techniques and 79% supported the investigation of new TBI techniques to further lower the lung dose.

CONCLUSION

There is no consistency in the practice patterns, methods for dose measurement and reporting of TBI doses among xxx institutions. The lack of a standardization precludes meaningful correlation between TBI doses and clinical outcomes including disease control and normal tissue toxicity. The xxx radiation oncology discipline is currently undertaking several steps to standardize the practice and dose reporting of pediatric TBI using detailed questionnaires and phantom-based credentialing for all xxx centers.

Connectionist models of neuropsychological disorders

Artificial neural networks ('connectionist models') embody aspects of real neuronal systems. But does studying the breakdown of performance in such models help us to understand cognitive impairments in humans following brain damage? Here we review recent attempts to capture different neuropsychological disorders using connectionist models with simulated lesions. We show how such lesion studies can be used to evaluate some of the standard assumptions made in neuropsychological research, concerning both double dissociations and associations between patterns of impairment. We also illustrate how lesioned models, like humans, can sometimes be more impaired on the easier of two tasks and demonstrate that connectionist models can incorporate forms of internal structure. Finally we discuss the utility of the models for understanding and predicting the effectiveness of different rehabilitation strategies. Future questions concern the role and possible development of internal structure within these models, whether the models can be generalized to larger-scale simulations, and whether they can accommodate higher-order linguistic disorders.

Breast cancer patients unknowingly dosing themselves with estrogen by using topical moisturizers

Abstract #4087

Background: Topically applied estrogens are more efficiently absorbed into the body than estrogens administered orally, due to the first pass effect by the liver. Estrogen receptor positive breast cancer patients need to avoid exogenously administered estrogen to minimize chance of recurrence. This is especially significant for women on aromatase inhibitor treatment,where topical estrogen may overcome the therapeutic effect. Also, non breast cancer patients using estrogen containing topical moisturizers may be unknowingly dosing themselves daily with estrogen, often for years, increasing their chances of developing breast cancer.
 Materials and Methods: Sixteen different topical moisturizers were purchased or donated from department stores or chain drugstores. None of the creams noted any estrogen content in their list of ingredients. Each of the sixteen commercial products was analyzed for estradiol, estriol and estrone utilizing High Performance Liquid Chromatography (HPLC). HPLC is commonly used in the pharmaceutical industry to provide component analysis. Detection was carried out through use of a Variable Wavelength Detector (VWD) and a Diode Array Detector.
 Results: Four samples contained greater than 0.40% estriol, one contained 0.17% estriol, and one contained 0.05% estrone, despite having no listing on the ingredient list.
 Discussion: Topical estrogens are considered effective in enhancing the “youthful look” of aging skin. Manufacturers are marketing incompletely labeled moisturizers containing estrogens. Consumers are unaware their moisturizer may be providing them with unwanted systemic estrogen exposure. The FDA cosmetics division is not presently testing for this potential risk for breast cancer patients. Other breast cancer advocacy groups and the FDA need to promptly repeat these procedures and also check for exotic "designer" estrogens.
 


Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4087.

Syllabic organization and deafness: orthographic structure or letter frequency in reading?

For hearing people, structure given to orthographic information may be influenced by phonological structures that develop with experience of spoken language. In this study we examine whether profoundly deaf individuals structure orthographic representation differently. We ask "Would deaf students who are advanced readers show effects of syllable structure despite their altered experience of spoken language, or would they, because of reduced influence from speech, organize their orthographic knowledge according to groupings defined by letter frequency?" We used a task introduced by Prinzmetal (Prinzmetal, Treiman, & Rho, 1986) in which participants were asked to judge the colour of letters in briefly presented words. As with hearing participants, the number of errors made by deaf participants was influenced by syllable structure (Prinzmetal et al., 1986; Rapp, 1992). This effect could not be accounted for by letter frequency. Furthermore, there was no correlation between the strength of syllable effects and residual speech or hearing. Our results support the view that the syllable is a unit of linguistic organization that is abstract enough to apply to both spoken and written language.

Quantitative analysis of disturbed cell maturation in dysplastic lesions of the respiratory tract epithelium

Autoradiographic patterns of [3H]thymidine incorporation, nuclear/cytoplasmic ratios (N/C), and the percentage of dark epithelial cells were analyzed in a group of epithelial lesions induced by 7,12-dimethylbenz[a]anthracene (DMBA) in rat tracheal transplants. It was found that similar lesions of different age exhibit the same labeling indices (LIs), therefore the lesions of different age were subsequently pooled in the following groups and studied by high resolution light microscopic autoradiography: squamous metaplasia without or with only mild atypia, squamous metaplasia with moderate atypia, squamous metaplasia with severe atypia, carcinoma in situ, and microinvasive carcinoma. Normal tracheal and esophageal epithelia were also analyzed. Whereas the normal tracheal basal layer exhibited an LI smaller than 1%, a clear difference between the carcinomas (in situ and invasive) on one hand (LI approximately 32%) and all the remaining epithelia on the other hand (LI approximately 18%) was detected. The LIs of the suprabasal cells exhibited a statistically significant difference between the squamous epithelia without atypia (LI approximately 2%) and the group comprising all the atypical lesions (LI approximately 9%). Gradients of increasing N/C (nucleus-cytoplasm ratios) values could be observed as the lesions increased in severity, especially in the middle and surface layers (e.g., in the surface layer regular metaplasia N/C = 0.08, squamous metaplasia with moderate atypia N/C = 0.26, and carcinoma in situ N/C = 0.50). Dark cells were absent in the normal esophageal epithelium, were present in moderate numbers in the basal layer of regular squamous metaplasia (18%), and increased markedly in the atypical epithelial lesions (approximately 50% in the atypical squamous metaplasias and 70% in carcinoma in situ). In the suprabasal layer dark cells increased from 3% in squamous metaplasia with moderate atypia to 28% in metaplasia with severe atypia and 56% in carcinoma in situ. The results confirm in a quantitative fashion that disturbances of cell maturation and cell proliferation are key features of dysplastic lesions induced by chemical carcinogens, and suggest the use of objective parameters for evaluation and classification of preneoplastic alterations.

Structure-function relationships of alkyl-lysophospholipid analogs in selective antitumor activity

This investigation was initiated in order to delineate the structure-function relationship of the anticancer alkyl-lysophospholipids and assess their degree of selective cytotoxicity toward neoplastic cells. A series of glycerol phosphocholine analogs with varying substitutions in the sn-1 and sn-2 position were tested for their inhibitory activity as measured by thymidine incorporation, clonogenic assays and effects on protein kinase C activity against a series of human leukemic cell lines and healthy bone marrow progenitor cells. The IC50 was determined for each of the compounds in each cell line and healthy bone marrow cells following a 4-h incubation. The data indicated that a 16-18 carbon chain at the sn-1 coupled with a short substitution at sn-2 had the broadest antitumor activity and was the least toxic to normal bone marrow cells. The results provide a number of useful leads toward the design and development of potentially more active phospholipid compounds.

Use of the polymerase chain reaction to detect hypermethylation in the calcitonin gene. A new, sensitive approach to monitor tumor cells in acute myelogenous leukemia

Based on the recent observations that, in a majority of patients with acute leukemia, the 5' end of the calcitonin gene was hypermethylated and abnormal DNA fragments were observed following HpaII restriction digestion, we have developed a PCR-based method to sensitively detect this abnormal methylation of the calcitonin gene in AML. Applying the concept of competitive PCR, a semi-quantitative correlation was obtained between the amount of hypermethylation and the amount of leukemic cells present. These results suggest that this method will be useful to monitor the amount of tumor cells in bone marrow from patients with AML.

Autologous bone marrow transplantation in acute leukemia with marrow purged with alkyl-lysophospholipid

Alkyl-lysophospholipids are anticancer agents that are selectively toxic to leukemic cells and relatively sparing of normal bone marrow cells. Thus, they would be likely candidates for purging remission marrows before autologous bone marrow transplant. One of the more promising agents is edelfosine, which could be safely used for purging without prolonging marrow recovery. Assays for marrow progenitor cells were performed before and after purging and cryopreservation in 64 patients. There was no significant reduction in colony formation after purging when compared with unpurged cryopreserved marrow, but there was a significant reduction after cryopreservation. Twenty-four patients with acute leukemia in second (16 patients) or third remission (3 patients), early relapse (3 patients), or in first remission with successfully treated extramedullary relapse (2 patients) received marrow-ablative chemotherapy and total body irradiation followed by infusion of marrow purged for 4 hours with 50 to 100 micrograms/mL of edelfosine. There were 9 lymphoblastic and 15 myelogenous leukemia patients. The median time to granulocyte recovery to 500/microL was 26 and 33 days for the 50 and 75 microgram/mL doses, respectively. The patient whose marrow was purged at the dose of 100 micrograms/mL failed to engraft. The median time to platelet recovery to 25,000/microL was 45 and 37 days for the 50 and 75 micrograms/mL doses, respectively. Twenty-nine percent of the patients remain disease free from 131 to 1,291 days, with a median of 356 days. These results have established that purging with 75 micrograms/mL of edelfosine is a safe dose and is recommended for a phase II trial.

Comparison of selective cytotoxicity of alkyl lysophospholipids

Alkyl lysophospholipids have been shown to be cytooxic to a number of neoplastic tissues. One, ET-18-OCH3, has been used to selectively purge leukemic cells from mixtures with normal marrow progenitor cells, in vitro and in vivo. We have measured the 50% inhibitory (IC50) effect of a series of ether lipids (EL) on leukemic cells (HL60, K562, Daudi, KG-1, KG-1a) and normal marrow progenitor cells. Cells were incubated with varying concentrations of EL for 4 hr and assayed for viability, [3H]thymidine incorporation and clonogenicity in semi-solid media. The effect on protein kinase C (PKC) activity was assayed for each compound. Compounds tested included three glycerophosphocholine analogs--ET-18-OCH3, ET-16-NHCOCH3, and BM 41.440. In addition, a lipoidal amine, CP 46665, an ethyleneglycolphospholipid, AEPL, and four single chain alkylphosphocholine analogs, HePC2, HePC3, HePC4 and HePC6 were also tested. During the period of incubation, the cells remained viable (greater than 70%) as judged by trypan blue dye exclusion. The glycerophosphocholines were the most active and showed the highest therapeutic index. The lipoidal amine was active, but toxic to normal marrow progenitor cells. The ethyleneglycolphospholipid was active against HL60, but not against the other cell lines. The single chain alkylphosphocholine analogs were less active. All of the compounds inhibited PKC activity; however, the glycerophosphocholines were the most inhibitory.

Purging of acute myeloid leukemic cells by ether lipids and hyperthermia

Ether lipids (EL) and hyperthermia have been shown to possess a relatively selective cytotoxicity to leukemic cells. In this study, the combined effects of EL (ET-18-OCH3, ET-16-NHCOCH3, or BM 41.440) and hyperthermia on the growth of hematopoietic progenitors, myeloid leukemic cell lines, and leukemic cells obtained from patients with acute myeloid leukemia (AML) were examined to determine if this combination resulted in a greater selective killing of leukemic cells than that achieved by either EL or heat alone. When the cells were treated simultaneously with EL (50 micrograms/mL) and hyperthermia (42 degrees C) for one hour, the killing of leukemic cell line cells was enhanced considerably. Among the three EL, however, the combination of ET-18-OCH3 and heat seemed to be the most cytotoxic to leukemic cell line cells with no effect on the growth of hematopoietic progenitors. An increase in the duration of treatment with ET-18-OCH3 to four hours with heat added during the last hour resulted in a further reduction of leukemic cell line cells while sparing 50% of hematopoietic progenitors after cryopreservation. The combined treatment with ET-18-OCH3 and heat also inhibited the growth of leukemic progenitors obtained from AML patients by 97% to 100%. These data indicate that the combined treatment with EL and hyperthermia might offer an efficient means to eliminate myeloid leukemic cells in vitro.

Experimental studies on the role of alkyl lysophospholipids in autologous bone marrow transplantation

The selective cytocidal effect of alkyl lysophospholipids against neoplastic cells while sparing normal cells make these ideal candidates for purging leukemic cells from bone marrows obtained during remission. To test the feasibility of such an approach, a murine model and an in vitro human cell model were developed. In the murine system a mixture of normal bone marrow cells and WEHI IIIB myelomonocytic leukemic cells was incubated with varying doses of 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-Me) for 24 hr before being injected into tail veins of lethally irradiated Balb/c mice. At doses of 20 and 100 micrograms/ml, long-term survivors were noted. The additional steps of freezing and thawing following incubation resulted in significantly longer survival with doses of 10 to 50 micrograms/ml, but were toxic to marrow stem cells at 100 micrograms/ml. In the in vitro model, normal marrow progenitor cells and leukemic cells (the promyelocytic cell line HL60) were exposed to varying concentrations of ET-Me for 1 and 4 hr alone or mixed, and clonogenicity was assayed by colony formation in semisolid medium during 7-14 days' incubation. At doses up to 100 micrograms/ml exposed for 4 hr normal progenitor cells were spared and HL60 colonies eliminated. Other phospholipids analogues were less effective in eliminating leukemic cells, but spared normal progenitor cells. A survey of fresh leukemic cells found varying degrees of sensitivity to ET-Me, indicating the need for testing a variety of compounds. These studies clearly indicated the potential usefulness of alkyl lysophospholipid compounds in selectively purging leukemic cells from remission marrows for autologous bone marrow transplantation.

Elimination of leukemic cells by the combined use of ether lipids in vitro

Two ether lipids, CP-46,665-1 (4-aminomethyl-1-[2,3-(di-n-decyloxy)-n- propyl]-4-phenylpiperidine) and ET-18-OCH3 (racemic 1-O-octadecyl-2-O-methylglycero-3-phosphocholine) have been shown to possess antileukemic activity in vitro. To explore the possible use of these compounds for purging remission bone marrow cells of leukemic cells, we examined the cytotoxic effect of these compounds on normal hematopoietic progenitor cells and leukemic cell line cells (HL-60, K-562, KG-1a, KG-1, and Daudi) by using the clonogenic assay. When cells were treated with CP-46,665-1 or ET-18-OCH3 (50 micrograms/ml for 1 h), these compounds did not inhibit the growth of normal progenitors, whereas the growth of the clonogenic leukemic cells was inhibited with differences in their sensitivities to the cytotoxic effect of CP-46,665-1 and ET-18-OCH3. Incubation of leukemic cells (HL-60 and Daudi cells) with both CP-46,665-1 (50 micrograms/ml) and ET-18-OCH3 (50 micrograms/ml) for 1 h resulted in a greater reduction of clonogenic leukemic cells than treated with each compound alone. Approximately a 3 log killing of clonogenic HL-60 cells and a 5 log killing of Daudi cells was achieved; however, the combined treatment of normal bone marrow cells with CP-46,665-1 and ET-18-OCH3 did not alter the growth of normal progenitors. This combined treatment also selectively eliminated the leukemic cells (HL-60 and Daudi cells) from a mixture (1000:1) of normal bone marrow cells and leukemic cells. It is conceivable that the pronounced difference in sensitivity to this combined treatment can be exploited for the elimination of residual leukemic cells in autologous remission marrow grafts.

Purging leukemic cells from simulated human remission marrow with alkyl-lysophospholipid

Alkyl-lysophospholipids (ALP) are analogues of 2-lysophosphatidylcholine that have been reported to have selective antitumor activity. These compounds could potentially be useful in purging bone marrow of leukemic cells in autologous marrow transplantation in acute leukemia. To determine the efficacy of pharmacological purging by ALP, we have designed a human assay system to mimic the conditions expected in the clinical setting of autotransplantation using remission marrow. A simulated remission marrow (SRM) was prepared by mixing normal marrow cells and HL60 cells in a ratio of 1,000:1. The effect of cryopreservation on ALP-treated normal, HL60, and SRM cells was examined. In separate experiments, ALP significantly reduced the number of clonogenic HL60 cells with no effect on normal marrow progenitors. The effect of ALP was more apparent after cryopreservation. Incubation of HL60 cells with 50 micrograms/mL ALP for four hours followed by cryopreservation resulted approximately in a 3 log reduction of clonogenic HL60 cells. ALP also selectively purged the small number of leukemic cells from SRM. In SRM, the data suggested that ALP had indirect cytotoxic activity on leukemic cells by enhancing the cytotoxic activity of monocytes in addition to its direct effect. We found no evidence that clonogenic HL60 cells decreased because of induction of differentiation by ALP. These data indicated that treatment of marrow cells with ALP offers an efficient means to eliminate leukemic cells from the graft.

Effect of alkyl-lysophospholipids on phosphatidylcholine biosynthesis in leukemic cell lines

Alkyl-lysophospholipids are ether analogues of lysophospholipids that have tumoricidal activity mediated through activation of macrophages or by direct effect on tumor cells by disturbance of phospholipid metabolism. The effect of racemic 1-octadecyl-2-methyl-sn-glycero-3 phosphocholine on phosphatidylcholine synthesis was investigated in sensitive (HL-60) and resistant (K-562) human leukemic cell lines. Radiolabeled lysophosphatidyl-choline, choline, and methionine incorporation into phosphatidylcholine was measured in intact cells exposed for 24 h to varying concentrations of the compound. In HL-60 cells, marked inhibition of phosphatidylcholine synthesis was demonstrated using lysophosphatidylcholine or choline as precursors, but no effect was observed on methionine incorporation. No effects were observed in K-562 cells. These investigations suggest that alkyl-lysophospholipids inhibit phosphatidylcholine synthesis via the acyltransferase reaction and from choline, but not from methionine.

Proper identification of anisakine worms

Luminal, gastric, intestinal and mesenteric forms of anisakiasis are known and can be encountered where raw or undercooked marine fish or squid are eaten. Although the anisakine nematodes which cause infection in humans are usually identified after surgical removal, laboratory personnel should be aware of their similarities to other nematodes. Cases have been reported of detection of larval nematodes in the throats or mouths of patients who have vomited or coughed. When such specimens are submitted to the clinical laboratory, problems in identification can be minimized by proper fixation and clearing. Systems for study involving clearing in phenol-ethanol and dissection to observe presence or absence of a ventricular appendix or intestinal cecum to distinguish Anisakis-, Phocanema- and Contracaecum-type larvae are described. Distinguishing characteristics are illustrated. The recovery of a Phocanema-type larva from a California woman is reported; the presence of the larvae in fish sold for human consumption in San Diego is exemplified.

Role of pH in production of hydrogen from carbohydrates by colonic bacterial flora. Studies in vivo and in vitro

Hydrogen produced by colonic bacteria and excreted in breath is a useful index of carbohydrate malabsorption. Since colonic contents are often acidic in individuals with carbohydrate malabsorption and in normal newborns, we determined the effect of colonic acidification on H2 production. Acidification of colonic contents by dietary means significantly reduced excess breath H2 excretion from 55.4 +/- 11.1 (SEM) to 12.2 +/- 3.1 ml/4 h (P less than 0.05) after administration of 0.3 g/kg of the nonabsorbable sugar lactulose to five normal adult subjects. Similarly, the breath H2 response to lactose was reduced or eliminated in two proven lactose malabsorbers after acidification. The correlation between pH and H2 production from carbohydrate was further investigated in adults and neonates, using an in vitro fecal incubation system. Glucose disappearance and H2 production were pH dependent and highly correlated (r = 0.94) in the pH range 5.5-7.6. Maximal production of H2 from glucose by fecal incubates occurred at pH 7.0-7.45. Inhibition of H2 production from carbohydrate occurred at acid pH. H2 per hour from glucose at pH 6.2 and 5.5 averaged 60.2% and 24.2%, respectively, of that produced at neutral pH. Rapid reversal of pH-induced inhibition by neutralization indicated a metabolic, rather than a bactericidal process. The observations indicate that the breath H2 response to malabsorbed carbohydrate is affected by colonic pH. It appears that the efficiency of bacterial carbohydrate metabolism in the colon is pH dependent.

Classification of cultured mammalian cells by shape analysis and pattern recognition

We have developed a method for classifying cultured cells on the basis of shape characteristics. High-resolution optical information on three-dimensional shape was obtained by anodic oxide interferometry. Each interference order formed in a cell was considered as a closed figure; measurement of 37 mathematical descriptors was carried out for each figure. The individual cells were classified according to the values of their descriptors. We used standard principles of pattern recognition, such as hierarchical cluster analysis and nearest neighbor analysis, as a basis for ordering the cells into groups. Alternatively, linear discriminant functions could be used, but they provided only a slight improvement in correct classification of the cells. We anticipate that the method will be appropriate for classification of cultured cell lines and for determination of the magnitude and direction of cell shape changes implicated in various biological processes.

Electron microscopic studies of bacteriophage M13 DNA replication

Intracellular forms of M13 phage DNA isolated after infection of Escherichia coli with wild-type phage have been studied by electron microscopy and ultracentrifugation. The data indicate the involvement of rolling-circle intermediates in single-stranded DNA synthesis. In addition to single-stranded circular DNA, we observed covalently closed and nicked replicative-form (RF) DNAs, dimer RF DNAs, concatenated RF DNAs, RF DNAs with single-stranded tails (theta, rolling circles), and, occasionally, RF DNAs with theta structures. The tails in theta molecules are always single stranded and are never longer than the DNA from mature phage; the proportion of theta to other RF molecules does not change significantly with time after infection. The origin of single-stranded DNA synthesis has been mapped by electron microscopy at a unique location on RF DNA by use of partial denaturation mapping and restriction endonuclease digestion. This location is between gene IV and gene II, and synthesis proceeds in a counterclockwise direction on the conventional genetic map.

Asymphylodora atherinopsidis (Trematoda: Monorchiidae) from the California grunion, Leuresthes tenuis, including a redescription

Asymphylodora (Asymphylodoroides) atherinopsidis from the California grunion, Leuresthes tenuis, a new host record, and jacksmelt, Atherinopsis californiensis, the type host, is redescribed and illustrated using more symmetrical as well as larger and smaller specimens than the holotype. The geographic distribution is extended from the type locality of Stinson Beach, Marin Co., California to Estero Beach, 10 km south of Ensenada, Baja California Norte, Mexico. Two tubular externat seminal vesicles opening independently into the internal seminal vesicle are reported apparently for the first time in a trematode. The genital pore is at the left posterolateral margin of the acetabulum which is midway between the lateral margins. Worms may grow to a length of 5.6 mm but eggs were present in one specimen 1.3 mm long.

The use of alpha-galactosidase and invertase in hollow fiber reactors

Invertase and alpha-galactosidase have been immobilized in hollow fiber cartridges with no detectable enzyme leakage and used for the hydrolysis of sucrose and raffinose, respectively. For both hollow fiber immobilized enzymes nearly complete substrate conversion is possible. Enzyme stabilities in polysulfonate hollow fibers which have been preconditioned with bovine albumin approach the stabilities of the free enzymes.

DNA replication in Chinese hamster ovary cells made permeable to nucleotides by tween-80 treatment

We have developed a method for permeabilizing CHO cells to nucleotides under conditions which allow most cells to remain viable. Permeabilized cells can carry out ATP-dependent, semiconservative synthesis of DNA. The data are consistent with the continuation of DNA synthesis in those cells in S phase at the time of treatment, possibly limited to completion of replicon synthesis without new initiations.

Hydrogen production in the rat following ingestion of raffinose, stachyose and oligosaccharide-free bean residue

Raffinose and stachyose were compared to cooked California Small White beans (CSW) containing 4% alpha-oligosaccharides (stachyose and raffinose) and to oligosaccharide-free CSW solids (residue from hexane and 70% ethanol extraction of CSW) as sources of hydrogen when ingested by rats maintained in life support systems. If the oligosaccharide content were the only hydrogen source in CSW, it would have had to be 25 times as potent as CSW, but raffinose was only five times and stachyose seven times as potent as CSW. Oligosaccharide-free residue was 0.4 to 0.5 as active as CSW. Hydrogen producing potencies of stachyose and raffinose were enhanced by feeding in combinations with residue. The increases in hydrogen production from the combinations were more than additive. Thus, CSW contains at least one 70% alcohol-insoluble substance which, in addition to the oligosaccharides, is essential to bring about quantitatively the physiological response to whole beans observed in rats.

Plant suspension culture media macromolecules-pectic substances, protein, and peroxidase

Macromolecules secreted into the media by a nondifferentiating suspension culture of tobacco cells were found to be composed of protein and polysaccharide, and to account for the viscosity of the media. The concentration, composition, and viscosity of these macromolecules changed significantly with the age of the culture and growth temperature. The concentration changed from 0.02 mg/ml in newly inoculated cultures to over 1 mg/ml in older cultures. The macromolecules contained from 6 to 18% protein and 3 to 4 mumoles hydroxy-proline/mg nitrogen, more than 20 times the level found in whole cells. The macromolecules contained 5 to 25% pectic substances whose carboxyl groups were either methyl esterified or combined with calcium. Arabinose, xylose, glucose, galactose, and mannose were identified in acid hydrolysates of the macromolecules. Peroxidase activity of the macromolecules increased as cultures became older. Peroxidase isoenzyme patterns changed with culture age and growth temperature. The relation of the macromolecules to cell walls and intercellular substances is discussed.

Glutaraldehyde activation of nuclear acid phosphatase in cultured plant cells

Cultured tobacco cells exhibited a nuclear reaction in the cytochemical test for acid phosphatase after exposure to 2 percent glutaraldehyde. A slight preference for adenosine monophosphate over beta glycerophosphate as substrate was noted, but the enzymatic activity was not typically 5' nucleotidase. Other aldehydes tested did not elicit the same enzyme response. Nucleolar localization was distinct from that in the rest of the nucleus. Assay for spectrophotometric measurements of enzymatic activity in vitro was developed as a modification of the Burstone procedure with naphthol AS-B1 phosphate and diazo blue B.