Effect of hypothermia on cell kinetics and response to hyperthermia and X rays

Hyperthermia is a potent radio enhancer. Studies using hypothermia in combination with irradiation have given confusing results due to lack of uniformity in experimental design. This report shows that hypothermia might have potential significance in the treatment of malignant cells with both thermo- and radiotherapy. Reuber H35 hepatoma cells, clone KRC-7 were used to study the effect of hypothermia on cell kinetics and subsequent response to hyperthermia and/or X rays. Cells were incubated at 8.5 degrees C or between 25 and 37 degrees C for 24 hr prior to hyperthermia or irradiation. Hypothermia caused sensitization to both hyperthermia and X rays. Maximum sensitization was observed between 25 and 30 degrees C and no sensitization was found at 8.5 degrees C. At 25 degrees C maximum sensitization was achieved in approximately 24 hr, cell proliferation was almost completely blocked, and cells gradually accumulated in the G2 phase of the cell cycle. In contrast to the effect of hypothermia on either hyperthermia or X rays alone, thermal radiosensitization was decreased in hypothermically pretreated cells (24 hr at 25 degrees C) compared to control cells (37 degrees C). The expression of thermotolerance and the rate of development at 37 degrees C after an initial heating at 42.5 degrees C were not influenced after preincubation at 25 degrees C for 24 hr. The expression of thermotolerance for heat or heat plus X rays during incubation at 41 degrees C occurred in a significantly smaller number of cells after 24 hr preincubation at 25 degrees C. The enhanced thermo- and radiosensitivity in hypothermically treated cells disappeared in approximately 6 hr after return to 37 degrees C.     

The effect of pH and lysosomal extract on rat liver metallothionein (Cd-thionein)

Was studied in vitro. The¹⁰⁹Cd-labeled protein was isolated by gel filtration and incubated with a lysosomal extract from the same source. No degradation was seen when the pH of the incubation medium was 5 or higher, whereas the degradation of Cd-thionein was completed in 2 h at a pH of 4.5. Dissociation of Cd²⁺ from thionein, which takes place to a fair extent at a pH below 5, appears necessary before the enzymatic breakdown of the thionein moiety can take place.     

Fluorescence decay of pyrene in small and large unilamellar L,α-Dipalmitoylphosphatidylcholine vesicles above and below the phase transition temperature

The fluorescence decays of pyrene in small and large unilamellar L,-dipalmitoylphosphatidylcholine vesicles have been investigated as a function of probe concentration and temperature. When the molar ratio of pyrene to phospholipid equals 1:3000, no excimer emission is observed and the fluorescence decays are mono-exponential. When this ratio is equal to or higher than 1:120, excimer formation is observed.Above the phase transition temperature the observed fluorescence decays of monomer and excimer can be adequately described by a bi-exponential function. The monomer decays can be equally well fitted to a decay law which takes into account a time-dependence in the probe diffusion rate constant. The fluorescence decay kinetics are compatible with the excimer formation scheme which is valid in an isotropic medium. The excimer lifetime and the (apparent) rate constant of excimer formation have been determined as a function of probe concentration at different temperatures above the phase transition temperature. The activation energy of excimer formation is found to be 29.4±1.3 kJ/mol. In small unilamellar vesicles the diffusion constant associated with the pyrene excimer formation process varies from 8.0x10^-7 cm²/s at 40°C to 2.2x10^-6 cm²/s at 70°C.Below the phase transition temperature the monomer decays can be described by a decay law which takes into account a time dependence of the rate constant of excimer formation. The lateral diffusion coefficient of pyrene calculated from the decay fitting parameters of the monomer region varies from 4.0x10^-9 cm²/s at 20°C to 7.9x10^-8 cm²/s at 35°C. No significant difference could be observed between the pyrene fluorescence decay kinetics in small and large unilamellar vesicles.Abbreviations SUV small unilamellar vesicles - LUV large unilamellar vesicles - DPPC dipalmitoylphosphatidylcholine - DMPC dimyristoylphosphatidylcholine - FRAP fluorescence recovery after photobleaching Part of this research has been presented at the 5th international symposium on surfactants in solution. Bordeaux, July 9th–13th 1984     

Functional aspects of the postovulatory follicle in the ovary of the African catfish,Clarias gariepinus,after induced ovulation

Summary In captive African catfish, Clarias gariepinus, ovulation was induced with human chorionic gonadotropin (HCG) 4 I.U./g body weight to study the function of postovulatory follicles (POFs). Ultrastructural and enzyme-histochemical data indicate that, apart from special theca cells, the granulosa of relative young POFs (i.e., from 16 h and 28 h after HCG-injection) is capable of producing steroids. Possible functions of the synthesized steroids are discussed. Histological comparison of POFs from stripped and from unstripped fish, as well as histochemical investigation of the contents of ovulated ova and granulosa of POFs at 48 h after HCG-injection, showed that the latter structure is involved in phagocytosis of the disintegrating ovulated eggs. The polysaccharide-lipid-protein material, initially taken up by heterophagolysosomes of the granulosa cells, subsequently undergoes fatty degeneration. The granulosa cells of the POFs showed strong acid phosphatase activity and abundant granular endoplasmic reticulum from 16 h after HCG-injection onward; heterophagolysosomes appeared at 32 h. These results indicate that after ovulation the phagocytotic function of the granulosa develops progressively. Autophagolysosomes, responsible for the final disintegration of POFs, become increasingly evident in the granulosa cells with increasing time after ovulation.     

In vitro culture of intramolluscan stages of the avian schistosome Trichobilharzia ocellata

Several different procedures for in vitro cultivation of intramolluscan stages of the avian schistosome Trichobilharzia ocellata were tried. A medium was found and culture conditions were established that not only supported in vitro transformation of miracidia into mother sporocysts, but also resulted in substantial subsequent growth; moreover, some degree of germinative development appeared to occur as well. Cerebral ganglia from uninfected adult snails of the intermediate host species, Lymnaea stagnalis, could produce factors promoting in vitro development of young mother sporocysts. Results are compared with data from the literature and it is concluded that greater success in in vitro culturing of young mother sporocysts of T. ocellata can be achieved than has hitherto been reported for other schistosome species. The same culture procedures were less successful when applied to other intramolluscan stages of T. ocellata, but can be used for in vitro maintenance of these stages. The procedures described here will be a useful tool in the study of schistosome-snail interactions in T. ocellata-L. stagnalis and possibly in other systems as well.     

Human c-fms proto-oncogene: comparative analysis with an abnormal allele.

The organization of the human c-fms proto-oncogene has been determined and compared with an abnormal allele. The human v-fms homologous genetic sequences are dispersed discontinuously and colinearly with the viral oncogene over a DNA region of ca. 32 kilobase pairs. The abnormal c-fms locus contains a small deletion in its 3' portion. DNA sequencing analysis indicated that it was 426 base pairs in size and located in close proximity to a putative c-fms exon.     

Improved Immunohistochemical Visualization of Helper/Inducer T-Cells by the Simultaneous Application of two Noncrossblocking Monoclonal Antibodies

We have studied the intensity of staining of helper/inducer T-cells in lymph node and tonsillar tissue using two commercially available monoclonal antibodies (OKT4 and Leu3a) with the indirect immunoperoxidase method. Paracortical and mantle zone helper/inducer T-cells were easily visualized by both monoclonal antibodies, but T-cells in the follicular center, though stained by Leu3a, were hardly demonstrable by OKT4. Excellent staining was obtained in the indirect immunoperoxidase procedure by incubating the sections with a 1:1 mixture of the two monoclonal antibodies which gave bright staining of individual cells throughout the lymphoid tissue. Dilution of the primary antibodies by 1:200 did not affect the results. It is concluded that the simultaneous application of OKT4 and Leu3a as primary antibodies in the indirect immunoperoxidase procedure is the method of choice for the in situ demonstration of helper/inducer T-cells.     

Epidemic of prosthetic valve endocarditis caused by Staphylococcus epidermidis.

In an epidemic of prosthetic valve endocarditis caused by Staphylococcus epidermidis the surgeon was found to be the source of contamination. The probable route was accidental puncture of gloves during operation. During the epidemiological investigation a second cluster of patients contaminated with Staph epidermidis during open heart surgery was found also related to one surgeon. This strain caused no detectable signs or symptoms of infection. Carriage of virulent staph epidermidis has rarely been recognised as a hazard but may have serious consequences.     

Human lens γ-crystallin sequences are located in the p12-qter region of chromosome 2

Summary The human -crystallin genes constitute a multigene family whose members are only expressed in the eye lens. The chromosomal location of these sequences has been determined by screening a panel of human/rodent hybrid cell lines containing overlapping subsets of human chromosomes for the presence of human -crystallin sequences. By correlating these genomic hybridization data with the chromosomal constitution of the somatic cell hybrids, all human -crystallin sequences could be assigned to chromosome 2. The use of human/hamster cell hybrids derived from human Burkitt lymphoma cells carrying a reciprocal translocation between human chromosomes 2 and 8, allowed a further localization of the sequences to the region 2p12-qter.     

Isolation of microorganisms on 3-butyn-1-ol and other acetylenic compounds

The microbial potential to degrade acetylenic compounds (alkynes) was investigated, and several fungi and bacteria were isolated on 2-propyn-1-ol, 3-butyn-1-ol, propynoic acid, and 2-butyne-1,4-diol. The results indicate that a wide variety of microorganisms may degrade alkynes in nature.