The survival of cytochalasin-induced polykaryons following exposure to cytotoxic agents

Using CHO-K1, HeLa S3 and two Walker lines (WR and WS) differentially sensitive to cis-diamminedichloroplatinum(II) (cisplatin), the survival after exposure to cisplatin, mitomycin C, vinblastine, vincristine or cytosine arabinoside has been determined either of clonogens or of cells rendered polyploid by post-exposure incubation in the presence of cytochalasin B (CB). It is suggested that the inhibition of cytokinesis by CB permits an assessment to be made of the fraction of damage whose expression is cell division-related, possibly including that resulting from a loss or malsegregation of genetic material. It was found that the response of polykaryons in comparison to clonogens was both agent- and cell line-dependent. After cisplatin exposure, polykaryon survival (defined as the ability to accumulate at least 16C DNA) declined exponentially with dose and was qualitatively, and to some extent quantitatively, similar to that observed previously after irradiation. In HeLa S3, giant cells induced by 10-20Gy irradiation in the absence of CB exhibited a radiation dose-dependent reduction in the relative frequency of highly polyploid cells which was similar to that observed in CB-induced polykaryons.

Comparison of cytobrush and cotton swab for Papanicolaou smears in pregnancy

Papanicolaou smears obtained using cytobrush or cotton swabs were compared in 222 pregnant women. There were no complications attributable to the cytobrush. Endocervical cell yields obtained with the brush were 70.9% compared to 41.9% with the swab (P = .0001). There was no difference between use of the swab and the brush in the prevalence of dysplasia (19 cases) nor was there any difference in the prevalence of dysplasia in the smears that contained endocervical and/or metaplastic cells (17/181 = 8.6%) compared to those not containing these cell types (2/24 = 8.3%). This study suggests that use of the cytobrush in pregnancy warrants further study because of the frequency with which smears are reported as inadequate because they lack endocervical and/or metaplastic cells.

Maternal mortality in Mississippi: 1987-1991

OBJECTIVE

To characterize the maternal mortality in the state of Mississippi for 1987-1991 and compare the maternal mortality from 1977-1986 with that of the last 5 years.

STUDY DESIGN

Factors associated with maternal mortality were obtained from death certificates, replies to questionnaires, medical records, and autopsy reports.

RESULTS

The maternal mortality rate in Mississippi for 1987-1991 (14.1/100,000) was not significantly different than for 1977-1986 (11.8/1000,000; P = 0.45). Over the last 5 years there was an increased incidence of direct obstetric deaths (50% vs 73%). During 1987-1991, toxemia as a cause of death for parturients decreased, while hemorrhage as a cause of maternal death increased. There was a rise in the incidence of patient related factors which were avoidable and which led to several deaths during 1987-1991.

CONCLUSION

The state's maternal mortality rate remains stable. Improved patient and health care provider's education are necessary to further decrease the incidence of maternal death in Mississippi.

Air bag injuries and occupant protection

Analysis of the investigations of crashes involving automobiles equipped with air bags verifies the estimations of the lifesaving and injury reduction benefits of this supplemental restraint system. Cases of air bag-associated injuries, primarily erythema, abrasions, and contusions of the lower face and anterior throat-upper chest, are identified as those most often observed. Corneal-scleral injuries were infrequently noted but are rarely found in crashes involving air bag deployments.

Cancer and pregnancy

The diagnosis of cancer rarely complicates pregnancy. Despite the fact that advanced disease is often encountered, there is no scientific evidence that the pregnant state alters the neoplastic process. Only through careful attention to the patient can the clinician detect cancer at an early stage and offer the patient reasonable hope for a cure.

Identification and categorization of the vascular patterns to muscles of the thoracic limb, thorax, and neck of dogs

Vascular patterns to thoracic limbs, thorax, and neck muscles were studied in 10 dogs (20 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 vascular pedicles. Size and location of pedicles were generally consistent, and any variations would not interfere with most muscle transfers. The cutaneous trunci, latissimus dorsi, sternothyroideus, sternohyoideus, deep pectoral, anconeus, ulnaris lateralis, and ulnar head of flexor carpi ulnaris muscles were identified as suitable for transfer. The cranial trapezius, caudal omotransversarius, cleidobrachialis, and caudal sternocephalicus muscles also had potential for use. Other muscles, because of inaccessibility or unfavorable vascular pattern, were not suitable candidates for transfer.

Isolation and structural analysis of the rat MyoD gene

We have cloned and determined the nucleotide (nt) sequence of a 6.5-kb genomic DNA fragment containing the rat MyoD gene (encoding a muscle regulatory factor, MyoD). Mouse fibroblasts transfected with this DNA display a high degree of conversion to a muscle phenotype, suggesting that this genomic clone contains sufficient sequence information to allow the production of the rat MyoD protein in these cells. The 6.5-kb genomic fragment contains the complete coding region of MyoD, distributed over three exons, plus 2.3 kb of 5'-noncoding sequence and 1.4 kb of 3'-noncoding sequence. Based on RNase protection assays, the major transcription start point of MyoD is located 210 nt 5' to a methionine start codon and 26 nt 3' to a TAAATA motif which bears similarity to a consensus recognition sequence (TATA) utilized by eukaryotic RNA polymerase II transcription complexes. The high degree of identity between the amino acid sequence of rat MyoD and the MyoD proteins isolated from other vertebrates indicates that this muscle regulatory protein has been evolutionarily conserved.

Zidovudine-interferon-alpha combination therapy in patients with advanced human immunodeficiency virus type 1 infection: biphasic response of p24 antigen and quantitative polymerase chain reaction

In an open-label dose-ranging pilot trial, 13 homosexual men with human immunodeficiency virus type 1 (HIV-1) p24 antigenemia after at least 6 weeks of zidovudine monotherapy were continued on zidovudine and given interferon-alpha, 1.25-7.5 x 10(6) units/m2 subcutaneously three times/week. Plasma p24 antigen levels demonstrated a biphasic response, falling initially in 11 patients by a mean of 50% (95% confidence interval, 36%-64%; P = .001) at a median of 11 weeks, but rising steadily thereafter (P = .001). CD4+ cell counts fell by a mean of 7.1 cells/mm3/week (P = .01). Higher initial CD4+ counts predicted greater p24 antigen reductions. At higher interferon doses no greater reductions in p24 antigen occurred, but side effects were more severe and CD4+ lymphocyte counts fell faster. Polymerase chain reaction quantification of HIV-1 DNA in 3 patients showed a biphasic pattern paralleling the p24 antigen response. In sum, although evidence of short-term effects was found, the combination showed no evidence of lasting antiviral activity beyond that achieved with zidovudine alone in patients with advanced HIV-1 infection.

Malignant hyperthermia

Malignant hyperthermia is a rare syndrome that occurs in genetically susceptible individuals who are exposed to frequently used inhalation anesthetics. The disorder is most common in children and young adults. It is triggered through a defect in the ability of skeletal muscles to concentrate and release calcium. Signs of malignant hyperthermia include hypercarbia, muscle rigidity and tachycardia. Temperature elevation is often a late sign of the syndrome. Treatment begins with stopping all inhaled anesthetics at the earliest sign of the syndrome. The use of dantrolene has significantly reduced mortality from malignant hyperthermia. No simple screening test exists. Family members or those with a suspicious history need to be counseled and should consider muscle biopsy and testing prior to surgery.

Benign symptomatic hyperandrogenism in a postmenopausal woman

Hyperandrogenemia in postmenopausal women requires an evaluation to exclude pathologic ovarian or adrenal causes. Our patient exhibited no signs of hypercortisolism, congenital adrenal hyperplasia, or adrenal or ovarian neoplasia based on biochemical testing and pelvic sonography. We hypothesized that unexplained androgen excess in our patient was due to the development of gonadotropin-dependent excess ovarian stromal androgen production. This syndrome may be comparable to gestational hyperreactio luteinalis where elevated gonadotropins stimulate ovarian stromal androgen production. If tumor can confidently be excluded, such women may benefit from gonadotropin suppression with long-acting GnRH-a.

4-hydroxythiazole inhibitors of 5-lipoxygenase

4-Hydroxythiazoles have been identified as potent inhibitors of 5-lipoxygenase in vitro exhibiting IC50's of less than 1 microM. An investigation of structure-activity relationships showed that the most potent inhibitors of this series are the 5-phenyl derivatives. The corresponding thiazolidin-4-one analogues were found to be relatively inactive. The 4-hydroxythiazoles were active inhibitors against 5-lipoxygenase in both intact rat polymorphonuclear leukocytes and human whole blood. The compounds were also selective inhibitors of 5-lipoxygenase, displaying only weak activity against other related enzymes, cyclooxygenase and 12- and 15-lipoxygenase.

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.