Mitotic Waves in Laticifers of Euphorbia marginata.

A successive pattern of nuclear divisions that result in mitotic waves has been observed within the coenocytic nonarticulated laticifers of embryos of Euphorbia marginata Pursh. These waves originate independently in the cotyledonary or hypocotyl portion of the laticifer and exhibit uni-or bidirectional movement at variable velocities. Individual nuclei or groups of neighoring nuclei in a laticifer were observed in a sequence of mitotic stages ranging from prophase to telophase; division activity varied with individual laticifers in an embryo. Two mitotic patterns were apparent in the embryo: a random pattern associated with various cells in the meristematic area, and a successive pattern restricted to the laticifer. A substance, synthesized by and restricted to the laticifer, may be associated with this mitotic pattern.

Growth hormone synthesized and secreted by human thymocytes acts via insulin-like growth factor I as an autocrine and paracrine growth factor.

There is increasing evidence that GH can influence immune function and that it is secreted by lymphocytes. In the present study we investigated the endogenous synthesis and secretion of GH and insulin-like growth factor I (IGF-I) from human thymocytes and evaluated the autocrine/paracrine effects of GH and IGF-I on T cell and thymic epithelial cell proliferation. First, the presence of thymic GH and IGF-I was detected by RIA of thymocyte extracts. Next, using a hormonal enzyme-linked immunoplaque assay, we found that thymocytes secreted GH and IGF-I. Further, we documented the endogenous synthesis of GH by human thymocytes using [35S]methionine labeling followed by immunoprecipitation, gel electrophoresis, and autoradiography. We then evaluated the physiological role of endogenously generated GH and IGF-I. Using an affinity-purified-GH polyclonal antibody, we observed a marked inhibition (P < 0.04) of phytohemagglutinin-stimulated thymocyte proliferation, suggesting an autocrine/paracrine role for the secreted GH. Further, we observed significant (P < 0.001) increases in thymocyte proliferation in cultures stimulated with varying doses of GH and IGF-I. Also, conditioned medium of human thymocytes (1 x 10(5) cells) stimulated with GH for 48 h contained a significant (P < 0.001) amount of IGF-I. Thymocyte proliferation stimulated by GH was significantly (P < 0.01) inhibited by monoclonal as well as polyclonal human IGF-I antisera. Finally, we studied the paracrine effect of thymocyte-secreted GH on human primary thymic epithelial cell (TEC) cultures. A significant (P < 0.05) increase in [3H]thymidine uptake in TEC cultures after GH addition was observed, which was abolished by GH antiserum. Polyclonal and monoclonal IGF-I antisera significantly (P < 0.05) inhibited GH-stimulated TEC proliferation. In summary, human thymocytes synthesize and secrete GH and IGF-I. Further, GH functions as an autocrine/paracrine growth factor in the human thymus via locally synthesized IGF-I.

Growth hormone secretion by human peripheral blood mononuclear cells detected by an enzyme-linked immunoplaque assay.

In order to evaluate the secretion of GH from human peripheral blood mononuclear cells (PBMC) and its possible role as a modulator of lymphoproliferation, we have developed a hormonal enzyme-linked immunoplaque assay. This assay captures GH between a monoclonal and polyclonal antibody. This is followed by adding substrate and a horseradish peroxidase-conjugated antibody against the polyclonal antibody which produces violet colored plaques where GH has been secreted. This assay is sensitive, specific, highly reproducible, and can detect picogram quantities of GH. Using this assay we have detected GH secretion from approximately 1% of human PBMC under unstimulated conditions. Regression analysis showed a linear relationship between the number of cells plated and the number of GH plaques formed. Therefore, GH plaques were formed by single cells or its progeny and did not represent aggregation of secreting cells. Preincubation of PBMC with cycloheximide, a protein synthesis inhibitor, completely abolished the formation of GH plaques which suggests that the PBMC were responsible for the synthesis of the secreted GH. In addition, we have also observed that stimulation of human PBMC with T-cell mitogens, Concanavalin A and PHA and the cytokine IL-2 led to significant increases in GH plaque area and number whereas stimulation with LPS, a B cell mitogen, was ineffective. The PHA and IL-2 induced increase in plaque number suggests that they can recruit noncommitted lymphocytes to actively secrete GH which raises the possibility that this secreted GH may serve as a growth factor in T cell proliferation. We conclude that this immunoplaque assay may be useful in evaluating the secretion of other peptides from human immune cells.

Delayed diagnosis of psychological erectile dysfunction because of the presence of macroprolactinemia.

Idiopathic hyperprolactinemia can be found in men with either normal or low serum testosterone (T) levels. The explanation for the differing effects on T of similar PRL levels has not been found. Macroprolactinemia, as a clinical entity, has been reported mostly in women. These macromolecules are biologically less active and/or are transported less easily across the capillary bed than the 22-kDa molecules. Therefore, women with elevated PRL levels retain normal menses and fertility. We studied six men, aged 28-53 yr (mean, 45 yr), in whom hyperprolactinemia was initially considered to be the cause of their erectile dysfunction. PRL levels ranged from 25-92 ng/mL (normal, 2-15 ng/mL), but T and gonadotropin levels were normal, suggesting that PRL was not disrupting gonadotropin and gonadal steroid function. The results of magnetic resonance imaging studies of the pituitary gland were normal. Separation by Sephadex G-100 column chromatography showed a predominance (85-90%) of big (60 kDa) and big big ( > 150 kDa) PRL, in contrast to the predominance of 22-kDa PRL in normal subjects. Nocturnal tumescence testing was normal, supporting the diagnosis of psychogenic impotence in these subjects, and potency returned after counseling. Hence, the biologically inactive macroprolactinemia did not cause any organic derangement in erectile function. It further obscured and delayed the appropriate diagnosis and treatment of these individuals.

Reproductive toxicity of ethylene glycol monoethyl ether tested by continuous breeding of CD-1 mice.

The reproductive toxicity of ethylene glycol monoethyl ether (EGEE) was evaluated in the Fertility Assessment by Continuous Breeding protocol. Both male and female CD-1 mice were given 0, 0.5, 1.0 or 2% EGEE in the drinking water and were housed as breeding pairs continuously for 14 weeks. Significant adverse effects on fertility were seen at 1 and 2% but not at 0.5%. After the continuous breeding phase of this test was completed, treated males were housed with control females and treated females with control males and fertility and reproduction were compared to the corresponding pairs of control male and control female mice. Both males and females from the 1 and 2% groups were affected. Testicular atrophy, decreased sperm motility and increased abnormal sperm were noted in the treated males, but no specific anomalies were detected in the females.

Comparison of metabolic systems required to activate pro-mutagens/carcinogens in vitro for sister-chromatid exchange studies.

Irradiated Syrian hamster fetal cells (feeder layer) and rat-liver homogenate (S9 mix) were used to compare their capacity to metabolize 3 known promutagens/carcinogens; BaP, 3-MC and DMBA. DNA-damaging potential was determined by the induction of SCE in V79 target cells. The S9 mix (1/20th strength) was toxic to the target cells and reduced the mitotic index by half with an exposure time of 2.5 h. The feeder layer was not toxic to the target cells and, therefore, was included for the duration of the Expt. The test chemicals elicited a dose-response with both activating systems. At similar concentrations of the test chemicals, the cells grown on the feeder layer showed a greater number of SCEs as compared to those activated by the S9 mix.

Cytological studies on onion root-tip cells treated with water-soluble extract of tobacco smoke condensate from commercial cigarettes.

The effect of water-soluble extract of tobacco smoke condensate (TSC) from two commercially available cigarettes with dirrerent types of filters was studied on the cytology of root-tip cells of onion (Allium cepa). One of the cigarettes had a 2-cm cellulose acetate filter, and the other had a filter comprised of 1 cm of cellulose acetate and 2 cm of activated charcoal. TSC from these cigarettes induced mitotic abnormalities. To investigate whether these two commercial filters could retain cigarette smoke component (s) responsible for mitotic irregularities, the cigarettes were defiltered, and TSC was prepared and tested on the young roots of onion. Observations revealed that the cytological effect of TSC from defiltered cigarettes was not significantly different from the effect of TSC from cigarettes with filters. Thus, the filters utilized in these cigarettes do not retain compound(s) responsible for mitotic irregularities in the root-tip cells of onion. With increasing concentrations (0.01% ot 0.1%) of TSC from cigarettes with filters and defiltered, precent mitotic abnormalities increased. These abnormalities included scattering, stickiness, lagging, condensation, and breaking of chromosomes during metaphase. Bridging and lagging of chromosomes were observed during anaphase.

Effect of benzo[a]pyrene on sister-chromatid exchange in fetal hamster liver exposed in utero.

Benzo[a]pyrene between 50 and 125 mg/kg administered maternally caused a dose-related increase in sister-chromatid exchange in fetal hamster liver cells. There was no difference on days 11, 13 and 15 of gestation in the sensitivity of fetal liver to benzo[a]pyrene.

Comparative study of the genotoxic properties of Eastern and Western U.S. shale oils, crude petroleum, and coal-derived oil.

A multiple bioassay approach was used to characterize and compare the genotoxicities of an Eastern U.S. (Kentucky) shale oil with the genotoxicities of Western U.S. shale oil, petroleum crude oil, and a coal-derived fuel oil. While the coal-derived oil was mutagenic in the Salmonella/microsome mutagenicity (Ames) assay, the shale oils had negligible to weak mutagenicity, and petroleum crude oil was not mutagenic. All the samples were also tested in the following mammalian test systems: an in vitro sister-chromatid exchange (SCE) assay in human lymphocytes and in vivo tests for induction of sperm abnormalities, micronuclei, and SCE in bone marrow of mice. Slight but statistically significant increases (P less than 0.001) in SCE in human lymphocytes were induced by all samples except petroleum crude oil. Neither sample induced a significant number of mutational events in either of the in vivo systems. In these preliminary studies no major differences in the genotoxicities of Eastern and Western shale oils were observed. The results were consistent with the following order of mutagenic potency: coal oil greater than Eastern and Western shale oil greater than petroleum crude oil.

Induction of sister-chromatid exchanges in human lymphocytes by extracts of particulate emissions from a diesel engine.

Particulate matter was collected from the emissions of a diesel-powered engine and the organic components were extracted. The extract induced a dose-related increase in sister-chromatid exchanges in human lymphocytes with a potency of about one-fifth that of benzo[a]pyrene.

Adrenal insufficiency--an unusual cause of shock in postoperative patients.

OBJECTIVE: To remind physicians that adrenal insufficiency can cause postoperative shock and that the manifestations are difficult to distinguish from those of sepsis. METHODS: We present detailed case reports of three patients who had hyperdynamic shock in the surgical intensive-care unit and describe their response to the cosyntropin stimulation test. RESULTS: All three patients were diagnosed as having adrenal insufficiency with use of the cosyntropin stimulation test. Two of the three patients rapidly recovered; however, because of delay in the diagnosis of adrenal insufficiency, the third patient succumbed to multisystem organ failure. CONCLUSION: The cases presented highlight the need to exclude adrenal insufficiency as a possible cause of hyperdynamic circulatory shock, particularly when no clear-cut diagnosis exists. Early recognition of adrenal insufficiency is important and can result in reversal of shock and prevention of death. Adrenal insufficiency can be diagnosed through screening random cortisol levels and by use of the cosyntropin stimulation test. Patients in addisonian crisis often respond to the first dose of glucocorticoid with dramatic improvement in blood pressure and systemic vascular resistance. Administration of glucocorticoid can thus lead to improved organ perfusion and recovery of organ function. Delays in diagnosis and treatment of acute hypoadrenalism can have a fatal outcome.

Right atrial thrombus in a patient with stage IV carcinoma of the lung: is the surgical treatment the correct choice?

Thrombus in the right atrium or ventricle is rare and carries a mortality rate of 40%. Death frequently occurs when the thrombus moves toward the pulmonary arteries. Emergent treatment is therefore required. However there is no clear consensus regarding therapeutic management. We present here a patient with right atrial thrombus who underwent surgical exploration of the right atrium and successful thrombectomy.

Dynamic role of kallikrein 6 in traumatic spinal cord injury.

Kallikrein 6 (K6) is a member of the kallikrein gene family that comprises 15 structurally and functionally related serine proteases. In prior studies we showed that, while this trypsin-like enzyme is preferentially expressed in neurons and oligodendroglia of the adult central nervous system (CNS), it is up-regulated at sites of injury due to expression by infiltrating immune and resident CNS cells. Given this background we hypothesized that K6 is a key contributor to the pathophysiology of traumatic spinal cord injury (SCI), influencing neural repair and regeneration. Examination of K6 expression following contusion injury to the adult rat cord, and in cases of human traumatic SCI, indicated significant elevations at acute and chronic time points, not only at the injury site but also in cord segments above and below. Elevations in K6 were particularly prominent in macrophages, microglia and reactive astrocytes. To determine potential effects of elevated K6 on the regeneration environment, the ability of neurons to adhere to and extend processes on substrata which had been exposed to recombinant K6 was examined. Limited (1 h) or excess (24 h) K6-mediated proteolytic digestion of a growth-facilitatory substrate, laminin, significantly decreased neurite outgrowth. By contrast, similar hydrolysis of a growth-inhibitory substrate, aggrecan, significantly increased neurite extension and cell adherence. These data support the hypothesis that K6 enzymatic cascades mediate events secondary to spinal cord trauma, including dynamic modification of the capacity for axon outgrowth.

Autogenous common facial vein or external jugular vein patch for carotid endarterectomy.

BACKGROUND: The purpose of this study was to determine whether common facial vein or external jugular vein are as good a vein patch as a saphenous vein for carotid patch angioplasty. METHOD: Retrospectively, 19 patients who underwent everted common facial vein or external jugular vein patch were compared with 199 patients who underwent saphenous vein patch carotid endarterectomy during 1989 to 1996. The two groups were compared clinically and by sonographic surveillance. The mean follow-up was 18+/-4 months for common facial vein/external jugular vein patients and 48+/-15 months for saphenous vein patch group. RESULTS: No significant differences in mortality or morbidity were observed among patients in whom everted common facial vein or external jugular vein was used as compared with saphenous vein. No bleeding, thrombotic event, dilation of the patch or aneurysmal degeneration and perioperative deaths occurred in either of the two groups. Duplex surveillance studies showed no significant difference in recurrent moderate (50-79%) and severe (80-99%) stenosis. CONCLUSION: Everted common facial vein or external jugular vein patch was comparable to other vein patches. This eliminates the comorbidity of groin incision. Also, using everted common facial vein or external jugular vein as vein patch saves saphenous vein to be used for other vascular procedures, such as coronary artery or lower extremity bypass.

Gamma-irradiation activates biochemical systems: induction of nitrate reductase activity in plant callus.

Gamma-irradiation induced high levels of nitrate reductase activity (NADH:nitrate oxidoreductase, EC 1.6.6.1) in callus of Haworthia mirabilis Haworth. Subcultures of gamma-irradiated tissues showed autonomous growth on minimal medium. We were able to mimic the effects of gamma-irradiation by inducing nitrate reductase activity in unirradiated callus with exogenous auxin and kinetin. These results revealed that induction of nitrate reductase activity by gamma-irradiation is mediated through in vitro activation of hormone synthesis in callus cells.

Kinetin-induced Changes in delta-Aminolevulinic Acid Dehydratase of Tobacco Callus.

Kinetin-induced changes in dry weight, soluble protein content, delta-aminolevulinic acid dehydratase activity, and chlorophyll content of two clones of Nicotiana tabacum L. callus were studied. Kinetin brought about a marked increase in the delta-aminolevulinic acid dehydratase activity of nongreen tissue just before induction of greening. The experimental data suggested a possible induction of specific chloroplast protein(s) during the kinetin-induced greening of nongreen tobacco tissue. Kinetin caused a decline in the delta-aminolevulinic acid dehydratase activity and chlorophyll content of the green callus used in the present study.

Effects of sucrose and kinetin on growth and chlorophyll synthesis in tobacco tissue cultures.

Investigations were carried out on the effects of various combinations of sucrose and kinetin concentrations on growth and chlorophyll production in a green and a nongreen clone of pith callus of Nicotiana tabacum L. It was found that 2 milligrams per liter or higher amounts of kinetin induced greening in the nongreen tissue. The observations suggested that growth of the callus and synthesis of chlorophyll and soluble protein are controlled by relative concentrations of sucrose and kinetin in the medium. Kinetin was found to be inhibitory for chlorophyll synthesis in the green callus.