Effect of caging variables on body weight and weight gain in mice

The effects on body weight of mixing litters to attain constant density of mice per cage, as opposed to housing litters in separate cages, was studied. Mixing litters resulted in a decreased weight gain between 21 and 42 da of age and a decreased adult body weight at 63 da of age compared to housing litters in separate cages, whether the separately housed litters were allowed to vary in density or not. Mixed litter housing also increased the variance of the body weight measures among males. Housing litters separately, even if it entails variable density of housing, appears to be the preferred method for studies involving inheritance of body weight.     

Bulling among yearling feedlot steers

The effect of ingestion of 250 ml X-ray contrast medium on resting gastrooesophageal sphincter pressure was studied in 10 normal human subjects. Twenty minutes after initiated intake of the contrast medium, a significant fall in sphincter pressure was recorded. In the light of studies on the neurogenic and hormonal regulation of the sphincter pressure it is attempted to account for this effect, and it is concluded that it must be a manifestation of a reflectory relaxation of the sphincter region. From a clinical point of view the consequence must be a demand for standardized conditions with regard to composition and pH of the contrast medium, time schedule and degree of abdominal compression in those cases in which radiological evaluation of the resistance against reflux is called for.     

Inhibition and reversal by beta-retinoic acid of hyperplasia induced in cultured mouse prostate tissue by 3-methylcholanthrene or N-methyl-N'-nitro-N-nitrosoguanidine

The effect of beta-retinoic acid (RA) on carcinogen-induced hyperplasia was studied in organ cultures of mouse prostate gland. 3-Methylcholanthrene (MCA), requiring metabolic activation, or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), not requiring activation, were used to induce hyperplastic changes. Treatment of cultures with MCA or MNNG stimulated cell proliferation and caused the alveolar epithelium to become hyperplastic. The development of this hyperplasia was inhibited when RA was added simultaneously with MCA or MNNG. However, RA had no significant effect on cell proliferation in untreated control cultures. Elimination of carcinogen from the hyperplastic cultures after 8 days of treatment did not reverse hyperplasia of the alveolar epithelium. When the withdrawal of MCA or MNNG was followed by treatment of the cultures with RA, hyperplasia was markedly reversed within 96 hours. Thus RA actively inhibited and reversed the effect of MCA and MNNG, two carcinogens that may have different mechanisms of action.     

Endogenous oncornaviral DNA sequences: evidence for two classes of viral DNA sequences in guinea pig cells

The nature of the endogenous viral DNA sequences in guinea pig cells was studied by hybridization. A segment of the viral RNA (r-VRNA) hybridizing to abundant (or reiterated) DNA sequences (R-VDNA) was isolated by recycling to a Cot of 300. The hybridization of the recycled VRNA, as well as the total VRNA, was followed by determining their kinetics and by Wetmur-Davidson analysis. The kinetics of hybridization of total VRNA were complex, did not follow a second-order kinetics, and revealed two slopes by Wetmur-Davidson analysis. The recycled RNA, on the other hand, had a second-order reaction rate expected of the hybridization between a single species of RNA and DNA sequences and yielded a single straight line in a Wetmur-Davidson plot. The Cot1/2 and slope of the recycled r-VRNA was almost identical to that of the abundant VDNA sequences obtained from the hybridization data of the total VRNA. Guinea pig 28S rRNA with or without recycling was used in monitoring hybridization rate. The kinetics of hybridization of 28S RNA followed a second-order reaction and produced a single straight line by Wetmur-Davidson plot, with a second-order reassociation rate constant of 9.6 x 10(-3) liters/mol-s, a Cot1/2 of 104 mol-s/liter, and reiteration frequency of 146. There was no difference in the kinetics of hybridization of 28S RNA before and after recycling. These experiments showed that guinea pig cells contain two classes of VDNA sequences. (i) R-VDNA sequences with a second-order reassociation rate constant of 8.2 x 10(-4) liters/mol-s, a Cot1/2 of 1,219 mol-s/liter, and a reiteration frequency of 12 represent 37.5% of the viral genome. (ii) Unique VDNA sequences with a second-order reassociation rate constant of 1.2 x 10(-4) liters/mol-s, a Cot1/2 of 7,692 mol-s/liter, and a reiteration frequency of 2 represent 62.5% of the viral genome.     

Isolation, physicochemical properties, and the macromolecular composition of the vitelline and fertilization envelopes from Xenopus laevis eggs

As a step toward defining in molecular terms the sperm-triggered block to polyspermy reaction established by the egg at fertilization, vitelline (VE) and fertilization (FE) envelopes were isolated from eggs of the Sounth African clawed toad Xenopus laevis and some of their physicochemical properties determined. Envelopes were isolated after lysis of the fertilized or unfertilized eggs by sieving techniques; isolated envelopes retained their in situ morphology as determined by electron microscopy. The isolated envelopes had different solubility properties and, in general, VE was more readily dissolved by aqueous solvents than FE, although both could be completely dissolved by detergents or chaotropic agents. Changes in envelope solubility correlated with the progression of the cortical reaction implicating a role for cortical granule material in modifying the solubility properties of the envelope. The VE and FE were composed of protein and carbohydrate with no lipid components detected. As determined by immunodiffusion experiments, the FE contained the same antigens as the VE plus components derived from the cortical granules and the innermost jelly layer, J. The macromolecular composition of the envelopes was determined by sodium dodecyl sulfate gel electrophoresis. The VE contained at least 11 glycoproteins with molecular weights ranging from 125 000 to less than 16 000 with two components (40 000 and 33 000) accounting for almost two-thirds of the total stainable material. The FE contained ten glycoproteins that had the same molecular weights as those in the VE. One glycoprotein component underwent a reduction in molecular weight from 77 000 to 67 500 when the VE was converted to the FE. This molecular weight change was interpreted as the probable result of limited proteolysis. In addition, the FE gel electrophoresis patterns contained macromolecular components derived from the cortical granules and jelly layer, J, consistent with the immunodiffusion experiments. These components were absent when the FE was prepared in the absence of Ca2+, suggesting a role for Ca2+ in binding the VE, cortical granules, and J components together. We concluded that the conversion of the glycoproteinaceous VE to FE at fertilization is caused by interaction of the VE with components from the cortical granules and jelly layer J. These interactions are of both a chemical and physical nature.     

Diagnosis and pathophysiology of paradoxical embolism

A review of the experience with 134 consecutive patients with germinal cell testicular neoplasia indicates that definitively accurate staging of the malignancy at presentation is the single most important prognostic factor. Nearly two-thirds of the patients with all types of germinal malignancies survived or died of other causes and the highest survival rates were seen among patients with earlier stages of seminoma. In recent years patients with all types of germinal malignancies of the testis have been treated by radical retroperitoneal lymphadenectomy with enhancement of survivals. Patients with seminoma and non-seminomatous tumors exhibited increased survival rates with node dissection. In 66 consecutive lymphadenectomies the complication rate was less than 14 per cent, with only 1 death related to the operation. Retroperitoneal lymphadenectomy not only affords therapeutic advantage but also provides an opportunity for accurate surgical staging of disease and allows for rational decision relative to additional treatment, radiation therapy or chemotherapy.     

Women's attitudes to mastectomy for breast cancer

One hundred patients who had been subjected to mastectomy for carcinoma were interviewed retrospectively to gauge their attitudes to any physical and/or emotional disabilities relating to their operation or disease. It was found that 40% of the patients had delayed for longer than a month after the onset of symptoms before seeking medical advice, but the reasons for this were not readily forthcoming. However, fear of mastectomy was not a common cause. Anxiety and embarassment due to an absent breast occurred in about one-third of patients, and did not diminish with time. Knowledge and the use of mammary prostheses was far from universal, and disturbingly only two-thirds were counselled in these matters by their medical advisers. Physical complications were common, particularly lymphoedema of the arm, and as expected this was closely related to the type and extent of treatment undertaken.     

Evidence for internalization of Escherichia coli into the aerial parts of maize via the root system

Escherichia coli introduced into the hydroponic growing medium of maize plants was detected 48 h later in the shoot. Decapitation of root tips or severing of the plant root system at the root-shoot junction enhanced bacterial internalization. The density of the bacteria in shoots of plants with damaged roots or removed root systems was 27.8 and 23.9 times higher than that in plants with intact roots, respectively. The concentration of viable cells in the hydroponic solution decreased over time from 9.3 x 10(6) CFU/ml at the time of inoculation to 8.5 x 10(1) CFU/ml 4 days thereafter. The number of E. coli cells associated with the roots also decreased with time, but a significant decline appeared only at 4 days postinoculation. At the time of sampling for E. coli presence in the shoot, 10(2) CFU/ml was present in the nutrient solution and 8 x 10(3) CFU/g was associated with the roots. The present study is the first to demonstrate internalization of E. coli via the root in a monocotyledonous plant.