Increased radioresistance of EJras-transformed human osteosarcoma cells and its modulation by lovastatin, an inhibitor of p21ras isoprenylation

Alterations in ras oncogene expression have been associated with increased cellular resistance to ionizing radiation. As an extension of studies with murine cell models, we have now explored the radioresponses of human osteosarcoma (HOS) sub-clones that differ in their EJras expression. Quantitative analysis revealed a tight correlation between the amounts of ras-encoded mRNA and p21 produced, and the degree of cell radioresistance. Interestingly, treatment of the ras-transformed cells with lovastatin, an inhibitor of p21ras post-translational processing via the mevalonate pathway, markedly decreased their radioresistance. Under the experimental conditions used, lovastatin prevented the membrane association, but not the biosynthesis, of p21. The decline in radiation resistance following lovastatin treatment could not be attributed to perturbation of cholesterol metabolism or to non-specific cell-cycle effects. In agreement, lovastatin did not alter the radiation responses of control HOS cells that do not express EJras, or those with an activated met oncogene. The results indicate that elevation in ras gene expression can lead to increased radioresistance of human tumor cells. It appears, however, that p21ras membrane localization is critical for maintenance of the radioresistant phenotype, thus providing a target for pharmacological intervention.

On a major radiation of freshwater snails in Tasmania and eastern Victoria: a preliminary overview of the Beddomeia group (Mollusca : Gastropoda : Hydrobiidae)

A total of 67 taxa, forming part of a major radiation of freshwater hydrobiid snails in Tasmania and eastern Victoria, are described. Four genera are recognised within the radiation: Beddomeia (47 taxa), Phrantela (13 taxa), Nanocochlea, gen. nov. (three taxa) in Tasmania and Victodrobia, gen. nov. (four taxa) in eastern Victoria. Fifty-nine of the species-group taxa are newly described, three of these being given subspecific status. Species-group taxa are separated using morphological data based on 78 characters from the shell, radula, non-genital and genital anatomy. Individual taxa appear to occupy a rather small range of habitats, although within the radiation species are found in many different environments ranging from large rivers to tiny seeps and springs or caves. Nearly all taxa occupy very small geographic ranges, 38 being known only from single localities. Maps indicating the distributions of described taxa and additional populations with similar shell morphologies (but otherwise unworked) are presented. A preliminary phylogenetic hypothesis based on a cladistic analysis, and an overview of the biogeography of the group are presented and conservation considerations are discussed.

Stress, appraisal, and coping in mothers of disabled and nondisabled children

The cognitive-behavioral model of stress and coping provided the framework for this study of mothers of physically disabled children (n = 69) and mothers of nondisabled children (n = 63). The first aim was to test for differences between groups in responses to stressful parenting events. As hypothesized, mothers of disabled children reported higher levels of depressive symptomatology. Differences in psychological distress and health status approached significance. The second aim was to explore the mediating influences of coping strategies and cognitive appraisals. As predicted, emotion-focused coping was related to increased psychological distress in mothers of disabled children whereas problem-focused coping was associated with decreased distress. Both relationships were significant even after controlling for differences in type of parenting stressor. Hierarchical regressions showed that 58 and 25% of the variance in psychological distress was explained by the independent variables; however, the predictors were different for the two groups of mothers. Factors that may explain the differential effectiveness of coping and appraisal, and clinical implications of this study are discussed.

A distraction technique for control of burn pain

Research has indicated that analgesics alone do not adequately relieve pain for 75% of patients with burns. The purpose of this study was to determine the effects of a distraction therapy, in which videos were used in combination with administration of analgesics, on intensity and quality of pain and on levels of anxiety in adults during burn dressing changes. The sample consisted of 17 patients who were randomly assigned to the treatment or the control group. The treatment group viewed video programs that were composed of scenic beauty accompanied by music. Each was asked to score his or her present pain intensity and pain rating index with the McGill questionnaire and anxiety with the Spielberger questionnaire before and after the dressing change. A nested general linear model using the "F" test in multiple regression analysis was adjusted for age, percent partial-thickness burn, and choice of topical agent demonstrated that the use of videos during the dressing changes significantly reduced pain and anxiety: present pain intensity (F = 8.69; p = 0.01), pain rating index (F = 5.57; p = 0.03), anxiety (F = 9.10; p = 0.01). It is recommended that the use of pain medication be augmented by use of videos during burn dressing changes.

Invertebrate abundance on Potamogeton nodosus: effects of plant surface area and condition

Using the macrophyte Potamogeton nodosus, we investigated variability in abundance of plant-dwelling invertebrates among individual plants. Plants were collected from three Potamogeton beds in Eau Galle Lake, Wisconsin, in June and August 1987. Invertebrate abundance on P. nodosus and the amount of plant surface area were positively correlated in both June and August. In August the amount of leaf damage (plant condition) was another important predictor of invertebrate abundance. Plant surface area and plant condition were responsible for most to almost all of the variability in invertebrate abundance on P. nodosus (R2 = 0.66 in June; R2 = 0.83 in August). The correlation between invertebrate abundance and plant condition in August and the lack of such a correlation in June indicated that plant age, rather than plant condition per se, was a causal mechanism for increased invertebrate abundance. Some plants were heavily colonized by invertebrates; a single plant collected in June held a total of 555 invertebrates, which included 177 chironomid larvae and 143 naidid worms. We estimate that the P. nodosus in a 20 × 60 m Potamogeton bed supported about 33 million invertebrates in June and approximately 30 million invertebrates in August. The use of lake management techniques in which plants are eliminated would therefore markedly reduce invertebrate abundance in the littoral zone, and would, in turn, deny fishes and waterfowl an important and abundant food resource.

Inhibition of glutathione reductase activity by a carbamoylating nitrosourea: effect on cellular radiosensitivity

Nitrosoureas inactivate cellular glutathione reductase. N,'N'1,3-bis(trans-4-hydroxycyclohexyl)-N'-nitrosoureas (BCyNU), a nitrosourea reported to selectively inhibit glutathione reductase (GR) activity, was examined to determine if it could be used as a means to inhibit cellular levels of this enzyme in radiobiology studies. Confirmation of drug-induced inhibition of GR activity was demonstrated using a cell-free model system employing purified GR. Cellular studies with Chinese hamster V79A03 showed that BCyNU decreased cellular glutathione content concomitant with an inhibition of specific GR activity. Under relatively nontoxic conditions, cellular exposure to BCyNU (25 microM, 0.25 h) either before or after radiation treatment, increased cellular radiosensitivity with the optimum time for drug addition being immediately following radiation. At a BCyNU dosage which produced less than or equal to 5% cell toxicity, a marked decrease in radioresistance was characterized as a reduction in both Dq (24 +/- 1.5%) and Do (8 +/- 0.5%) concomitant with a 25 +/- 2% decrease in cellular glutathione reductase (GR) activity. At cytotoxic drug dosages (25 microM, 1 h; cell survival 79 +/- 7%), a marked radiosensitization manifested by a 1.25 +/- .07-fold reduction in the Dq was observed concomitant with a 49 +/- 4% decrease in GR activity. Using cells enriched in different stages of the cell cycle, BCyNU caused cell-age dependent cytotoxicity with preferential killing of cells in the radioresistant late-S-phase, a likely explanation for its radiosensitizing capabilities at high drug dosages. Data obtained at nontoxic drug dosages suggest that GR-inactivation may be an important component of cellular response to free-radical induced damage.

The laryngeal mask airway. An unusual complication

The laryngeal mask airway is an important addition to the anaesthetist's armamentarium, but its use is not without the possibility for misfortune. We encountered an unusual and potentially serious complication. A patient's epiglottis became trapped between the pliable grates in the mask portion of the laryngeal mask and partially obstructed his airway. Should this problem occur and remain unnoticed, in addition to the problem of airway obstruction during the anaesthetic, the oedematous epiglottis could be severely injured upon removal of the laryngeal mask. This, in turn, could result in airway obstruction requiring emergency treatment.

DNA damage in cultured human skin fibroblasts exposed to excimer laser radiation

Ultraviolet excimer lasers are being considered for use in a variety of refractive and therapeutic procedures, the long-term biologic consequences of which are unknown. The effect of sublethal doses of 193-nm laser radiation on cellular DNA was examined in cultured human skin fibroblasts. In contrast to 248 nm, treatments with the 193-nm laser radiation below 70 J/m2 did not cause significant pyrimidine dimer formation in the skin cells. This was indicated by the lack of excision repair activities (unscheduled DNA synthesis assay), and further demonstrated by direct analysis of pyrimidine dimers in DNA from irradiated cells. However, a low level of unscheduled DNA synthesis could be detected following irradiation at 193 nm with 70 J/m2. Both the 193-nm and 248-nm radiation were able to induce chromosomal aberrations, as indicated by a micronucleus assay. A dose-dependent increase in micronuclei frequency was observed 48 and 72 h after laser irradiation. These results indicate that exposure of actively replicating human skin fibroblasts to sublethal doses of either 193- or 248-nm laser radiation can result in genotoxicity.

Increased radiation resistance in transformed and nontransformed cells with elevated ras proto-oncogene expression

The cellular Ha-ras oncogene, activated by missense mutations, has been implicated in intrinsic resistance to ionizing radiation. This study shows that the overexpression of the unmutated gene (proto-oncogene) may also be involved in how the cells respond to radiation. The experimental system consisted of mouse NIH 3T3-derived cell lines which carry multiple copies of a transcriptionally activated human c-Ha-ras proto-oncogene. Both tumorigenic (RS485) and revertant nontumorigenic subclones (PR4 and 4C3) which have high levels of ras expression exhibited a marked increase in radioresistance as measured by D0 compared to control NIH 3T3 cells. Other nontransformed cells with elevated levels of ras (phenotypically revertant line 4C8-A10) also had a significantly increased resistance to radiation, further indicating an association between ras and radioresistance. The increased radioresistance of the RS485 and phenotypic revertants could not be explained by a differential expression of the myc or metallothionein I genes or by variations in cell cycle. The correlation between increased ras proto-oncogene expression and radioresistance suggests that the ras encoded p21, a plasma membrane protein, may participate in the cellular responses to ionizing radiation.

Hookworm folliculitis

A case of persistent folliculitis in a 21-year-old man was demonstrated to be due to Ancylostoma caninum larvae. Treatment with oral thiabendazole was curative. Cutaneous larva migrans may be due to A caninum, but this presentation appears to be unique. The literature concerning etiology and pathogenesis of larva migrans is discussed with reference to this case.

Brain protein synthesis in rabbits following low level aluminium exposure

1. Infant rabbits received s.c.injections 3 times weekly of low doses of aluminium (A1) maltolate (0.5-1.5 mg Al/kg body wt) or aluminium lactate (8 mg Al/kg body wt) from 5 or 10 days of age to 14 or 22 days of age. 2. Brain was used to provide a cell-free protein synthesizing system and this system exhibited increased activity in preparations from Al-exposed infants. The mRNA fraction obtained from the brain polysomal RNA also was more active following Al exposure. 3. The synthesis of immunoprecipitable calmodulin was significantly elevated.

The turtle's revenge: a case of soft tissue Mycobacterium chelonae infection

A case of cutaneous Mycobacterium chelonae infection with sporotrichoid spread and extensive antibiotic resistance is presented. Control of this problem was only achieved after extensive debridement and grafting of the involved limb. The importance of surgery in management is discussed and the literature is reviewed.

Translatability of mRNA from brain of infant rabbits exposed chronically to aluminium

1. Polysomes were isolated from the brain of infant rabbits at 22 days of age. The animals received s.c. injections 3 times weekly of aluminium (Al) maltolate (3 mg Al/kg body wt) or Al lactate (16 mg Al/kg body wt) from 5 days of age. 2. The polysomes were used to direct the incorporation of [14C]leucine into peptides in a brain protein synthesizing system and exhibited a decreased activity when obtained from aluminum exposed infants. 3. The mRNA obtained from the polysomes was used to direct the incorporation of [35S]methionine into peptides in an mRNA dependent rabbit reticulocyte lysate. The translatability of the mRNA derived from aluminum exposed infant brains was significantly lower than that of preparations from control infant rabbits. 4. Al bound to maltolate, a ligand soluble in lipids as well as water, was considerably more detrimental to brain protein synthesis than Al bound to lactate.

Dynamics of filter feeding in Corbicula fluminea (Bivalvia: Corbiculidae)

Filtration rates of Corbicula fluminea were measured using 2-μm microspheres from three riverine habitats which differed in ambient suspended particle concentration; rates were measured at particle concentrations spanning the range for the three habitats. Filtration rates were significantly different across the three habitats, and were inversely correlated with the mean ambient suspended particle concentrations: 66.4 mL/h for 11 mg/L, 100.2 mL/h for 7 mg/L, and 144.9 mL/h for 4 mg/L for the Tombigbee, Ouachita and Tangipahoa rivers, respectively. However, the weight of particles filtered by clams from the three rivers was not significantly different. These results indicate that C. fluminea can make physiological adjustments to its filtration rate to achieve some "optimal" rate of particle removal. Within each habitat, particle concentration had a significant effect on filtration rates for the Tombigbee River and Tangipahoa River populations; maximal filtration rates were observed in the range of ambient particle concentrations for each habitat. The effects of particle size and type on filtration rates were examined for clams from the Tombigbee River. Filtration rates were measured with microspheres of various sizes, natural suspended particles, and Chlorella. Filtration rates were highest with natural suspended particles; these particles were also the smallest in size (3 × 5 μm). Rates were also highest when measured with particles representative of the size range encountered in the field. There was no significant difference in filtration rates measured with similar-sized microspheres and Chlorella. Pseudofeces were produced by all sizes of clams from each population at particle concentrations greater than 12 mg/L. For the Tombigbee River population, pseudofeces were produced by all sizes of clams at particle sizes greater than or equal to 16 μm. These data indicate that there are potential morphological constraints on the clam gill that limit the range of particle concentrations and sizes that can be processed. Laboratory observations also demonstrated the capacity for deposit feeding in C. fluminea. Our data indicate that filter feeding in C. fluminea is a complex phenomenon, requiring an understanding of how the physiological process of feeding is influenced by morphological constraints imposed upon gill functioning and by the temporal effects of environmental variables. In addition, the plasticity in the filter-feeding response and the capacity for alternative feeding modes contribute to the success of C. fluminea as an invasive species.

A prospective trial of prophylactic intravenous immune globulin for the prevention of infections in severely burned patients

A prospective randomized double-blind study evaluated the efficacy of i.v. immune globulin in preventing infectious complications in severely burned patients. Fifty patients were randomized to receive either i.v. immune globulin or placebo. Each group of patients was treated with twice weekly infusions for either 5 weeks or until the patients' wounds were covered. Patients treated with the immune globulin had an immediate correction of their depressed serum IgG levels, however there was no change in the infection or mortality rates. No adverse effects were noted with the immune globulin treatments. One potential weakness of this study was the greater burn surface area and a higher incidence of inhalation injury in adult patients treated with i.v. immune globulin compared to controls.

Pseudallescheria boydii mycetoma in northern New England

Mycetoma is a chronic subcutaneous fungal infection characterized by tumefaction, draining sinuses, and grains. It is most common in the tropics but occasionally occurs in the United States. We report a case of a mycetoma affecting the foot of a 38-year-old mentally retarded man from northern New England. The causal organism was identified as Pseudallescheria boydii, the most common cause of mycetoma in the United States. The patient showed a partial response to 8 months of ketoconazole therapy.

Clinical observations concerning active duty veterans with post-Vietnam adjustment problems

Clinical observations by Navy psychiatrists and psychologists who concurrently conducted therapy groups at three separate military treatment facilities between 1981 and 1984 were recorded. The reasons they returned to active duty or remained in the service, how and why they were referred to therapy, issues that arose in group therapy, and factors that were believed to have influenced the successful outcome are summarized and discussed.

The effects of intermittent exposure to suspended solids and turbulence on three species of freshwater mussels

A laboratory experiment was performed to evaluate the effects of intermittent suspended solids exposure on the unionid clams Quadrula pustolosa, Fusconaia cerina and Pleurobema beadleanum. Intermittent impacts of this type are important effects of commercial navigation traffic in freshwater. Clams were cyclically exposed to turbulence alone or accompanied by 600-750 mg litre(-1) of suspended inorganic solids for 9 days. Clams exposed to suspended solids every 3 h reduced their metabolic rate but did not shift from the mainly protein based catabolism of controls. Feeding impairment was apparently compensated for by a reduction in metabolic demand. Conversely, clams exposed every 0.5 h to suspended solids shifted to virtually complete reliance on non-protein body stores as indicated by O:N values averaging 197.

Effects of scavengers of reactive oxygen and radical species on cell survival following photodynamic treatment in vitro: comparison to ionizing radiation

The effects of various scavengers of reactive oxygen and/or radical species on cell survival in vitro of EMT6 and CHO cells following photodynamic therapy (PDT) or gamma irradiation were compared. None of the agents used exhibited major direct cytotoxicity. Likewise, none interfered with cellular porphyrin uptake, and none except tryptophan altered singlet oxygen production during porphyrin illumination. The radioprotector cysteamine (MEA) was equally effective in reducing cell damage in both modalities. In part, this protection seems to have been induced by oxygen consumption in the system due to MEA autoxidation under formation of H2O2. The addition of catalase, which prevents H2O2 buildup, reduced the effect of MEA to the same extent in both treatments. Whether the remaining protection was due to MEA's radical-reducing action or some remaining oxygen limitation is unclear. The protective action of MEA was not mediated by a doubling of cellular glutathione levels, since addition of buthionine sulfoximine, which prevented glutathione increase, did not diminish the observed MEA protection. The hydroxyl radical scavenger mannitol also afforded protection in both kinds of treatment, but it was approximately twice as effective in gamma irradiation as in PDT. This is consistent with the predominant role of OH radicals in ionizing radiation damage and their presumed minor involvement in PDT damage. Superoxide dismutase, a scavenger of O2, acted as a radiation protector but was not significantly effective in PDT. Catalase, which scavenges H2O2, was ineffective in both modalities. Tryptophan, an efficient singlet oxygen scavenger, reduced cell death through PDT by several orders of magnitude while being totally ineffective in gamma irradiation. These data reaffirm the predominant role of 1O2 in the photodynamic cell killing but also indicate some involvement of free radical species.

Effect of DL-buthionine-S,R-sulfoximine on the growth of EMT6 and RIF mouse tumors

The response of murine EMT6 and RIF tumors to DL-buthionine-S, R-sulfoximine (BSO), a glutathione (GSH) depletor, given either as a single dose, continuous oral administration, or in multiple doses, was determined with the use of a tumor-growth-delay assay. BSO consistently caused significant tumor growth delay in EMT6 tumors, which reached 5-7 days (two doubling times) after a single BSO dose (40 mumol/kg or 4 mmol/kg), 3 days (one doubling time) with continuous oral administration (20 mM), and 9 days (three doubling times) with daily BSO administrations (4 mmol/kg) starting at the time of tumor inoculation. Growth inhibition persisted after discontinuation of BSO treatment. Some complete tumor regressions were observed. Only slight tumor growth delay (one doubling time) was observed in RIF tumors at all treatment modes. No direct correlation was observed between tumor GSH content and the effects on tumor growth. In vitro BSO pretreatment (2 mM, 24 hr) of EMT6 tumor cells prior to tumor inoculation, which reduced cellular GSH levels to 34% of controls, did not influence subsequent tumor growth. Pretreatment of mice with BSO (4 mmol/kg, 1 daily sc injection for 7 days) prior to tumor inoculation led to a reduction of tumor takes by 25% when compared to 100% tumor takes in untreated mice. These data imply a BSO-induced change in the host response to tumor development.

The influence of cellular glutathione content on cell survival following photodynamic treatment in vitro

The influence of cellular glutathione (GSH) levels on the response to photodynamic treatment (PDT) in vitro was determined in cells which either were depleted of GSH by buthionine sulfoximine (BSO) or were genetically GSH deficient. The effects of GSH depletion on cellular radiosensitivity were studied in parallel for the purpose of comparison. BSO treatments which reduced GSH levels in four cell lines (CHO, V79, EMT6, RIF) to approximately 80% of controls, 30% of controls, or undetectable levels uniformly decreased cell survival. This decrease was directly related to GSH depletion levels and was expressed mainly in a reduction of the width of the survival curve shoulder (Dq). GSH level-dependent aerobic radiosensitization following BSO treatment was likewise found in all four cell lines. In contrast to PDT, however, cell survival changes were expressed in the dose slopes (Do's) of the survival curves. Cell survival of GSH-deficient human fibroblasts (GM 3877) was decreased following PDT and gamma irradiation when compared to their normal counterparts (GM 5659). In both modalities the difference was mainly due to a reduction in the Dq's, while the Do's were only slightly affected. The augmented response to PDT was not caused by interference by BSO or GSH with either cellular porphyrin uptake or singlet oxygen production during the photodynamic process. Possible mechanisms of GSH effects on PDT were discussed.