Use of UV irradiation to reduce false positivity in polymerase chain reaction

UV irradiation provides a simple and efficient way to minimize contamination or false positivity which often occurs in laboratories performing routine PCR tests. Here, we characterize several parameters of the effect of UV irradiation on DNA template, primers, deoxynucleoside triphosphate and Taq polymerase. UV irradiation of DNA results in the formation of pyrimidine dimers and thus prevents them from being effective templates in subsequent PCR. Reduction of the HIV DNA templates in polypropylene microcentrifuge tubes by more than 1000-fold can be achieved by UV irradiation. The sensitivity of the primers is sequence- and concentration-dependent. Oligonucleotides with neighboring thymine bases are more susceptible to UV than those without. Taq polymerase is highly UV sensitive, whereas deoxynucleotide triphosphate is relatively UV resistant.

In vitro chemosensitivity testing in chronic lymphocytic leukaemia patients

Twenty-nine samples from eighteen patients with chronic lymphocytic leukaemia (CLL) were used in a direct comparison of in vitro response to chlorambucil measured in a metabolic (MTT) and dye exclusion (D.Ex) assay. Reduced ability to produce formazan corresponded to a reduced number of dye-excluding viable cells and a significant correlation was found between dose-response measured in the two assays. Initial low absorbance values obtained with untreated control cells in the MTT assay were effectively overcome by increasing both the cell seeding density and MTT exposure time with the consequent increase in assay sensitivity. The MTT assay provided qualitatively similar dose-response data to that obtained in the D.Ex assay. A wide range in in vitro response was seen for both pretreatment and treatment patient groups. In vitro dose-responses were seen to coincide with decreasing or stable white cell counts, taken around the time of sampling, in samples from 4 patients. Less marked dose-responses were observed for 2 patients considered clinically resistant to chlorambucil. The MTT assay would seem, therefore, to be applicable to in vitro assay of cell response in CLL.

Analysis of lymphocytes, monocytes, and neutrophils from human immunodeficiency virus (HIV)-infected persons for HIV DNA

The human immunodeficiency virus (HIV) infects and depletes or alters the function of cells involved in immune responsiveness. While both T helper lymphocytes and monocyte/macrophages can be infected via cell-surface CD4 in vitro, previous studies showed that few blood cells express HIV RNA in vivo. This study used DNA amplification to determine the levels of HIV DNA in purified lymphocytes, monocytes, and neutrophils from HIV-infected asymptomatic individuals and persons with AIDS. The average numbers of HIV DNA copies in lymphocytes from AIDS patients and asymptomatic individuals were similar (approximately 100-140 copies/150,000 cells). However, when expressed on the basis of numbers of CD4+ T cells, AIDS patients' cells contained approximately 2.5 times more HIV DNA. While HIV DNA was present in lymphocytes from all 27 subjects, little or no HIV DNA was observed in monocytes or neutrophils. Only 1 asymptomatic person contained levels of HIV DNA in monocytes (125 proviral copies/150,000 cells) that were comparable to levels expressed in lymphocytes (160/150,000). While expression of monocyte HIV DNA in this person was persistent over at least 8 months, it was not observed in neutrophils, suggesting that monocyte HIV DNA did not originate in myeloid precursors. This study shows that in AIDS or asymptomatic HIV infection, lymphocytes are the predominant infected cell found in blood.

Treatment of trochanteric ulcers with cranial sartorius and rectus femoris muscle flaps

Five dogs with pressure ulcers over the greater trochanter were treated by debridement and transposition of the cranial part of the sartorius or the rectus femoris muscle. Both muscles had vascular anatomy that allowed transposition based on a major vascular pedicle. All wounds healed promptly by primary intention and no ulcer recurred. The cranial sartorius flap technique was easier to perform than the rectus femoris technique.

Concordance of polymerase chain reaction with human immunodeficiency virus antibody detection

To evaluate the correlation of detection of human immunodeficiency virus (HIV) by polymerase chain reaction (PCR) with detection of HIV antibody, 271 simultaneous serum and peripheral blood mononuclear cell samples were examined from 242 persons whose activities placed them at increased risk for HIV infection: 142 from homosexual men, 86 from hemophilic men, and 43 from heterosexual partners of HIV-infected persons. PCR was performed using the gag region primer pair SK38/39 and the env region primer pairs SK68/69 and CO71/72. Amplified HIV DNA was detected using specific oligomer probes. Of 63 HIV antibody-positive samples, 58 (92%) had HIV DNA by PCR. Of 208 HIV antibody-negative samples, 7 (3.4%) had HIV DNA by PCR. On follow-up, 4 of the latter persons were seropositive when next tested; 2 were well and antibody- and PCR-negative; 1 had died of a stroke before retesting. Thus, PCR detects HIV in most antibody-positive persons; detection is increased by use of multiple primer pairs. PCR-positive antibody-negative specimens may indicate HIV infection in which antibody has not yet developed or may be false-positive PCR results. When PCR is discordant with HIV antibody, testing of additional specimens and clinical follow-up are necessary to assess HIV infection status.

Flow cytometric studies of the survival of cytochalasin-induced polyploidy in Chinese hamster ovary cells

A method has been developed to estimate the post-irradiation survival of cytochalasin B-induced polyploidization of adherent Chinese hamster ovary cell using the flow cytometer. After exposure to radiation, surviving cells are allowed to become polyploid in the presence of cytochalasin, and are detached using trypsin, fixed by the addition of glutaraldehyde and stained using mithramycin. DNA content distributions are polymodal, and the absolute number of cells per culture in any given ploidy class is estimated by reference to a non-fluorescent bead internal standard, detected using forward scatter. Post-irradiation survival is defined as the ability to reach a given DNA content, and is reduced exponentially with dose. A bioassay to determine optimum cytochalasin concentrations can be derived from the relative size of the 2C (G0/G1) peak in the DNA content distribution. At culture densities greater than about 8 x 10(4) cell/cm2 the relative number of cells reaching at least 16C is reduced, but this inhibition is partially reversible by an increase in the medium glucose concentration, but not by the use of cytochalasin D or dihydro B.

Identification and anatomic categorization of the vascular patterns to the pelvic limb muscles of dogs

The vascular patterns to pelvic limb muscles were studied in 6 dogs (12 limbs) to identify muscles most suitable for transposition in the treatment of large wounds. Gross dissection of injected specimens and angiography were used to identify the vascular pedicles. The vascular pedicles to several muscles were generally consistent, and any variations would not interfere with most muscle transfers. The cranial part of the sartorius, gracillis, semitendinosus, and rectus femoris muscles were identified as suitable candidates for transfer. The caudal part of the sartorius, cranial tibial, and long digital extensor muscles have segmentalized vascular patterns that would limit its arc of rotation.

Nuclear lysate sedimentation measurements of peripheral blood lymphocytes from radiotherapy patients

When isolated nuclei of human lymphocytes are challenged with 2 M NaCl a histone-free-DNA-protein (HF-DNA) complex is released. In a linear sucrose gradient (pH 8.0) the sedimentation distance of HF-DNA is reduced when immediately isolated from cells irradiated in vitro. At low doses, if irradiated cells are incubated at 37 degrees C the sedimentation behaviour approaches that of unirradiated cells (i.e. repair). In the present study such repair was usually complete within 1 h. The radiation damage to lymphocytes from a healthy donor group and three patient groups consisting of new patients (before radiotherapy), well patients (2 to 6 years post-radiotherapy) and patients with complications attributed to radiotherapy was similar. The lymphocytes from most healthy donors and new patients demonstrated complete repair of radiation damage following an incubation of 1 h at 37 degrees C. However, 2/29 (6.9 per cent) healthy donors and 2/25 (8 per cent) new patients demonstrated poor repair. Of those patients now attending with 'bowel complications' attributed to radiotherapy 7/16 (44 per cent) demonstrated poor repair. In contrast, all those (11/11) described as 'well and complication-free' showed good repair.

Prevalence of human immunodeficiency virus type 1 DNA in hemophilic men and their sex partners. Hemophilia-AIDS Collaborative Study Group

Polymerase chain reaction (PCR) was used to detect human immunodeficiency virus (HIV)-1 DNA in peripheral blood mononuclear cells to assess in hemophilic men whether any were HIV-seropositive but uninfected or seronegative but infected and in seronegative sex partners of seropositive hemophilic men whether any were infected. Of 40 seropositive men, 38 (95%) were PCR-positive; one was PCR-indeterminate and one PCR-negative. None of 41 seronegative men who used only donor-screened, virus-inactivated coagulation factor products were PCR-positive. However, two of six who received noninactivated products were PCR-positive; one had low T-helper cell counts and died of unrelated causes and the other had seroconverted 11 mo later. PCR with a second primer pair also detected HIV-1 DNA in these two men. None of 25 seronegative female sex partners of seropositive men, including six men with AIDS and seven with AIDS-related symptoms, were PCR-positive. These data suggest that most seropositive hemophilic men are HIV-infected; whether some are infected with defective virus remains to be resolved as does the infection status of seropositive PCR-negative men. Identification of two seronegative PCR-positive men supports the possibility that HIV-1 DNA can be detected before seroconversion.

A novel dye exclusion assay for measurement of cell response following in vitro exposure to radiation or drugs

A novel dye exclusion assay based on differential staining of fixed cells has been evaluated using the MOLT4 (T-lymphoblastic leukaemia) and DAUDI (Burkitt lymphoma) cell lines. Reproducible differential staining was found with fixed samples kept for up to 2 months. A small increase (less than 13%) in the proportion of stained cells was observed over the first 30 days in fixative. Reproducible dose-response data were obtained with cells treated with radiation or drugs and assayed after 4 days in culture. This ability to fix cells prior to measurement of viability is of general use particularly where time constraints prevent haemocytometer counting. More specifically, it may have potential use in the field of chemosensitivity testing particularly where large sample numbers require rapid processing.

Interaction between rifabutin and human immunodeficiency virus type 1: inhibition of replication, cytopathic effect, and reverse transcriptase in vitro

Rifabutin (ansamycin; LM427), a semisynthetic rifamycin derivative, inhibits the replication of human immunodeficiency virus type 1, the virus etiologically linked to acquired immunodeficiency syndrome. The inhibition of virus production was observed in human immunodeficiency virus type 1-infected peripheral blood mononuclear cells both by reverse transcriptase assay and virus-antigen assay. In addition, rifabutin effectively reduced human immunodeficiency virus type 1-associated cytopathic effect to OKT4-positive cells. Virion-associated reverse transcriptase was also markedly inhibited by rifabutin. The inhibitory dose of rifabutin was nontoxic to lymphoid cells, which further suggests that it might serve as a useful agent in the therapeutic modalities of acquired immunodeficiency syndrome.

Specific adsorption of HTLV-I to various target human and animal cells

In this report, we describe a flow cytometric analysis of HTLV-I specific binding to fresh and cultured cells on a single cell basis. This assay uses rhodamine hydrocarbon tagged, purified HTLV-I virions according to the procedure originally described for avian retroviruses. Successful HTLV-I transmission was detected by analysis of integrated HTLV-I DNA, virion-associated reverse transcriptase, and/or intracellular HTLV-I core antigen p19 expression. Only a specific virus-cell interaction was detected because nonrhodamine-tagged homologous virus or related HTLV-II interfered with tagged HTLV-I binding. In contrast, an unrelated, nonlabeled animal retrovirus was unable to block tagged HTLV binding. Of the cell lines tested, 2 nonlymphoid mammalian and 3 human lymphoid bound significantly high to moderate levels of HTLV-I-tagged virions. The other three human lymphocyte cell lines were insensitive to HTLV-I adsorption. A direct correlation was observed between HTLV-I binding sites and infectivity of human lymphoid cells alone and not other nonlymphoid animal cells. Fresh normal human mononuclear cells bound low levels of HTLV-I virions. As expected, T lymphocytes demonstrated more binding than did the non-T cell population. Enhancement of HTLV-I cell binding in a subpopulation of mononuclear target cells was achieved with phytohemagglutinin (PHA) activation and interleukin 2 (IL2) stimulation, which correlates well with previously published infectivity studies.

Quantitative assay of human T-cell leukemia/lymphoma virus transformation

The in vitro transformation of normal T-lymphocytes by human T-cell leukemia/lymphoma virus (HTLV-I) is possible utilizing cocultivation techniques. We now report on a quantitative assay for HTLV-I transformation. Transformed cell lines were produced by cocultivation of either preactivated (phytohemagglutinin and T-cell growth factor) or nonactivated peripheral blood mononuclear cells with an equal number of lethally irradiated HTLV-I-positive donor cells (MT-2). After 14 days in liquid culture, transformed cells were plated in a 2-layer soft agarose system with or without T-cell growth factor (TCGF). Colony formation among 50 normal controls was observed at varying efficiencies with a mean number of 179 colonies (range, 6-599) in the presence of TCGF (up to a 2-log difference). The day 14 T-cell cultures demonstrated relatively low colony-forming efficiencies (less than or equal to 0.1%) and enhanced colony formation in the presence of TCGF. Day 14 after cocultivation was chosen for this assay based on a dose-response relationship between colony formation and the virus-positive donor cell inoculum and the known kinetics of colony growth of normal activated T-cells. An analysis of individual colonies indicated that they were of target cell origin and HTLV-I positive. Recombinant beta-interferon in increasing concentrations caused a decrease in colony formation as measured in this assay. Long-term cell cultures (2-18 months) showed higher colony-forming efficiencies (up to 1.0%) which were not enhanced by TCGF. The ability to quantitatively evaluate transformation via colony counts will provide an opportunity to study differences in transforming efficiencies attributable to varying target cells, donor cells, or blocking factors such as interferons, drugs, or anti-HTLV-I antibodies.

Specific absorption rate and tissue temperature in local hyperthermia

Specific absorption rate (SAR) and tissue temperature were measured for a total of 83 treatments in 33 patients who received local hyperthermia treatment for cancer. The patients were grouped into three categories according to tumor size. Hyperthermia was induced by 13.56 MHz electromagnetic energy applied using capacitive coupling. A method is described for evaluating SAR from the tissue temperature traces at any time in the treatment when a step change is made in applied power. The method is possible only if the temperature traces are free from interference and the total power delivered to the patient is monitored. Mean values of SAR ranged from 4.6 to 89 W kg-1 depending on the treatment site. Satisfactory heating was achieved for superficial tumors, with temperatures greater than 42 degrees C being recorded in 69% of treatments. For axillary nodes only 4% of treatments exceeded 42 degrees C. For cervix tumors an idealized tumor model was used to estimate tumor temperature from the temperature and SAR measured in the adjacent normal tissue. From the model it appears necessary either to raise the systemic temperature to 40 degrees C or to increase the SAR by at least a factor of 4 to obtain a temperature of 42 degrees C in a typical tumor. Measurements of SAR and temperature are essential for feedback control of computer models which, in principle, could provide a complete distribution of temperature during a hyperthermia treatment. Furthermore, measured SAR provides a direct comparison of the power deposition from different treatment machines in a clinical environment. The data presented form a basis for comparison with the clinical use of other heating systems.

Dynamic and nonspecific dispersal of human T-cell leukemia/lymphoma virus type-I integration in cultured lymphoma cells

The progression of HTLV-I proviral integration over a 3-year period of in vitro culture was examined in two human lymphoma lines, Hut 102 and MJ. Using specific HTLV-I molecular clones and a Southern analysis at different cell passages, Hut 102 increased from 2 to 19 integrated proviral integrations while MJ increased to at least 25 different integrations by passage 43. During the progress of increased superinfection and novel integration in vitro some of the previous proviral integrations were lost from the cultures. The 19 integrations of late passage Hut 102 cells were shown to be dispersed to 19 different human chromosomes by analysis of 34 distinct rodent X Hut 102 somatic cell hybrids which segregated human chromosomes (and included proviral integrations) in different combinations. The two primary integrations in Hut 102 were located on human chromosomes 4 and 20, respectively. A similar pattern of nonspecific integration was observed in somatic cell hybrid analysis of the 25 proviral integrations of MJ. The dynamic infection-reintegration process in vitro revealed in these studies may confuse experimental verification of potential cis acting functions of HTLV-I in the as yet poorly understood mechanism of neoplastic transformation.

High IgM antibody to human T-lymphotropic virus type I in systemic lupus erythematosus

Twenty-six percent of 53 systemic lupus erythematosus sera had high levels of IgM antibody to human T-lymphotropic virus Type I, significantly more than the 5% of normal controls. Neither IgG antibodies to Type I virus nor IgM or IgG antibodies to Type II virus were increased in lupus. Further analysis using competition immunoassay and Western blot techniques also suggested that the IgM Type I antibodies in lupus sera were directed against viral antigens but did not completely exclude a nonviral reaction. Other studies also have not found IgG antibodies to the Type I virus but have not tested for IgM antibodies. Our study suggests that human T-lymphotropic virus Type I or a related virus may be involved in the pathogenesis of some cases of systemic lupus erythematosus.

The survival of cytochalasin-induced multinucleation following irradiation of Chinese hamster ovary cells

Chinese hamster ovary cells were cultured for up to 280 hr in medium containing 1.75 mcg/ml cytochalasin B. The distribution of the number of nuclei per cell in unirradiated cultures on the 6th day was unimodal with some cells containing 27 or more nuclei. The DNA content distribution was in contrast polymodal with the means of the two terminal major peaks occurring at approximately 40 and 80 units of DNA content (antimodes at 29 and 58 units), where 1 unit is the content of untreated G1 cells. Irradiation (gamma, 137-Cs) at doses up to 10 Gy caused an exponential reduction in the proportion of plated cells able to reach high nucleus- or DNA-contents. The reduction due to 5 Gy was stable at least up to 280 hr in culture. The accumulation of total DNA in the culture was well-fitted by a Gompertz function, with little further increase after 230 hr when the average DNA content per cell reached about 90 units.