Search PubMed⌕ Search

Biomedical subjects

K Smith

Publications and source records attributed to K Smith.

At least 469 records · Page 26Linked to original sources
PubMed1986

Toxicity and DNA damage induced by 1-nitropyrene and its derivatives in Chinese hamster lung fibroblasts.

1-Nitropyrene and its chemically synthesised derivatives were investigated for their cytotoxicity and ability to induce DNA-strand breaks in Chinese hamster lung fibroblasts. Both 1-nitrosopyrene (0.25-60 micrograms/ml) and 1-aminopyrene (0.25-25 micrograms/ml) were cytotoxic, and induced the formation of DNA lesions, which were measured as DNA single-strand breaks after sedimentation in alkaline sucrose-density gradients. Higher doses of 1-aminopyrene (25-60 micrograms/ml) inhibited the formation of DNA single-strand breaks. 1-Nitropyrene was not toxic (0.25-60 micrograms/ml) and induced low levels of detectable DNA strand breaks, whilst N-acetyl-1-aminopyrene was inactive. The post-mitochondrial supernatant fraction of Aroclor-induced rat-liver containing 4 mM NADPH (S9 mix) did not promote the activation of 1-nitropyrene. In fact DNA strand breaks induced by either 1-nitropyrene or 1-nitrosopyrene was abolished in the presence of S9 mix. The 1-nitropyrene reduced intermediate, N-hydroxy-1-aminopyrene was synthesised by the reduction of 1-nitrosopyrene with ascorbic acid. In the presence of ascorbic acid, 1-nitrosopyrene caused a 5-fold increase in the number of DNA single-strand breaks when compared to cells treated with 1-nitrosopyrene alone. The results are discussed in terms of the metabolic activation of 1-nitropyrene and 1-aminopyrene in Chinese hamster lung cells.

Animals↗
PubMed1986

Sperm morphologic features as a prognostic factor in in vitro fertilization.

To determine whether there is a prognostic value in the percentage normal sperm morphologic features in a human in vitro fertilization (IVF) program, the authors conducted a prospective study in women with bilateral tubal damage. Based on the percentage of morphologically normal spermatozoa, the patients were divided into four groups: group I, normal morphologic features between 0% and 14%; group II, 15% to 30%; group III, 31% to 45%; and group IV, 46% to 60%. One hundred ninety successful laparoscopic cycles were evaluated. In group I, 104 oocytes were obtained, of which 37% fertilized, but no pregnancy resulted; in group II, 81% of 324 oocytes were fertilized, with a pregnancy rate per embryo transfer (ET) of 22%; in group III, 82% of 309 oocytes were fertilized, with a 31% pregnancy rate; and in group IV, 91% of 69 oocytes were fertilized, with a pregnancy rate of 12%. Probability models indicated that there was a clear threshold in normal sperm morphologic features at 14%, with high fertilization and pregnancy rate in the groups with normal sperm morphologic features greater than 14%.

Embryo Transfer↗
PubMed1986

The induction of DNA adducts in mammalian cells exposed to 1-nitropyrene and its nitro-reduced derivatives.

1-Nitropyrene, 1-nitrosopyrene and 1-aminopyrene were investigated for their ability to induce covalently bound DNA adducts in calf thymus DNA and Chinese hamster lung fibroblasts. Xanthine oxidase catalysed the induction of one major and one minor DNA adduct in 1-nitropyrene- or 1-nitrosopyrene-treated calf thymus DNA, whilst 1-aminopyrene was inactive. These compounds did not form detectable DNA adducts in the absence of xanthine oxidase. The major DNA adduct produced by 1-nitropyrene and 1-nitrosopyrene in calf thymus DNA co-migrated on h.p.l.c., and the structure was consistent with that previously described by others as N-(deoxyguanosin-8-yl)-1-aminopyrene. The compounds were investigated for their ability to form DNA adducts in Chinese hamster lung fibroblasts. 1-Nitropyrene (5.2 pmol/mg DNA/h) and 1-nitrosopyrene (129 pmol/mg DNA/h) formed a single DNA adduct in Chinese hamster lung cells which co-eluted on h.p.l.c. with the C-8 deoxyguanosine adduct isolated from 1-nitropyrene-treated calf thymus DNA. 1-Nitrosopyrene was the most efficient compound investigated for the production of the C-8 guanine adducts. In contrast, 1-aminopyrene (14.7 pmol/mg DNA/h) induced the formation of a DNA adduct which did not co-elute with the C-8 guanine adduct. The data presented here suggest that 1-nitropyrene and 1-aminopyrene are metabolized to reactive intermediates which form different DNA adducts in Chinese hamster lung fibroblasts.

Animals↗
PubMed1986

Selective peritoneal lavage in the management of comatose blunt trauma patients.

Comatose blunt trauma patients undergo diagnostic peritoneal lavage to aid in the management of severe injuries. In deference to routine performance of lavage, patients felt to be a risk for abdominal injury were prospectively studied by using selective criteria for lavage. One hundred consecutive comatose blunt trauma patients were studied; five underwent urgent celiotomy for refractory hypotension. Five criteria for lavage were: history of postinjury hypotension, abdominal physical findings suggestive of underlying abdominal injuries, evidence of fracture of the bones of the trunk and/or femur, blunt trauma of unknown etiology, and operative general anesthesia required for nonabdominal injuries. Fifty-five patients satisfied at least one of the above criteria and underwent peritoneal lavage. Forty patients not satisfying the criteria were observed without peritoneal lavage, as it was felt they had a decreased probability of serious abdominal injury. One of these patients had a minor liver laceration found at the time of autopsy following his death from severe head injury. None of the other patients had evidence of intra-abdominal injury by autopsy or subsequent clinical course. Utilizing the selective criteria, none of the 100 consecutive blunt trauma patients had major delay in abdominal diagnosis or missed significant abdominal pathology defined by operation, clinical course, or autopsy. Routine peritoneal lavage in all comatose blunt trauma patients may subject the patient to unnecessary risk, waste valuable time, increase the cost of care, and alter subsequent diagnostic procedures. Based on this small study, it appears that comatose blunt trauma victims not fulfilling the criteria may be effectively evaluated without the use of peritoneal lavage.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Injuries↗
PubMed1986

Suicidal behavior among "normal" high school students.

The findings of a pilot study, focusing on suicidal behaviors among 313 high school students in the Midwest, are discussed. Of all the students who participated in the study, 62.6% reported some degree of suicidal ideation or action, including 8.4% who had actually made a suicide attempt. The current study provides a linchpin between the studies of adolescent suicide attempt rates and the studies reporting on percentages of adolescents who made suicide attempts. When the percentage of attempters who made attempts but did not seek medical help is taken under consideration, these two groups of studies become equivalent. Apparently, suicide is a personal concern for most high school students--a problem that warrants immediate attention.

Adolescent↗
PubMed1986

The effects of the availability of diet on the levels of exoglycosidases in the supragingival plaque of macaque monkeys.

Supragingival plaque from macaque monkeys was assayed for 13 exoglycosidase enzymes, with appropriate p-nitrophenylglycosides and N-acetylneuramin-lactose used as substrates. Protein in each plaque sample was quantitated with a Coomassie Brilliant Blue dye binding assay, and the specific activity of each enzyme was calculated. In monkeys fed a starch-based diet, fasting resulted in significant increases in the levels of alpha-L-fucosidase, beta-N-acetyl-D-glucosaminidase, beta-N-acetyl-D-galactosaminidase, and neuraminidase. Such changes are consistent with the hypothesis that plaque bacteria degrade salivary glycoproteins for their growth and maintenance in both the presence and especially the absence of dietary food. In contrast, fasting monkeys previously fed a sucrose-rich diet showed no significant alterations in the specific activities of those enzymes whose levels were increased in the starch-based diet group. It is considered likely that, under the conditions prevailing when the sucrose-rich diet is fed, the effective and maximal utilization of sucrose by plaque bacteria necessitates the increased mobilization of nitrogen sources, including the amino sugars of glycoproteins.

Animals↗
PubMed1986

Research-informed comments on the treatment of suicidal inpatients.

Because there is debate about the benefits of hospitalization for the suicidal patient, it is vital that issues relating to the assessment and treatment of such patients be studied. Research studies, chiefly arising from the Menninger Suicide Research Projects, are summarized as they focus on these issues. Why particular kinds of hospital treatment can benefit the seriously suicidal patient and why certain treatment philosophies can seemingly increase the risk of death are among the issues discussed. Clinicians are urged to sharpen their assessment questions and to develop a focused, articulated understanding of the circumstances which might precipitate a suicidal crisis as well as the particular aims of the act for a given individual.

Data Collection↗
PubMed1986

Stimulation of human committed bone marrow stem cells (CFU-GM) by chloramphenicol.

Chloramphenicol, an antibiotic associated with reversible bone marrow suppression and fatal aplastic anemia, was found to increase human bone marrow granulocyte-macrophage colonies (CFU-GM) in vitro. Maximal stimulation was at a concentration of 1.0 micrograms/ml (3.1 microM), with inhibition at concentrations greater than 10 micrograms/ml. This effect was noted in normal donors and in children with neutropenia of various etiologies. Stimulation was ablated by depletion of bone-marrow-adherent cells and was restored by addition of peripheral-blood-adherent mononuclear cells. The stimulatory effect appears to be specific for chloramphenicol, as numerous structural analogues of chloramphenicol, including its three stereoisomers, did not show stimulation. The stimulation was present at plateau concentrations of colony-stimulating activity, suggesting that the stimulatory effect is not due to elaboration of excess colony-stimulating activity by chloramphenicol. We hypothesize that low concentrations of chloramphenicol stimulate CFU-GM by a highly specific interaction with adherent mononuclear cells and elaboration of an undefined growth factor.

Bone Marrow Cells↗
PubMed1985

A comparative analysis of glial and neuronal markers in the retina of fish: variable character of horizontal cells.

The immunohistochemical localizations of the enzymes glutamine synthetase, carbonic anhydrase-C, and the intermediate filament protein GFA were examined for potential neuroglial specificity in the retinas of several types of fish. Both glutamine synthetase and carbonic anhydrase-C appear to be characteristic markers for retinal Müller cells. However, the horizontal neurons of most fish examined also possess high levels of carbonic anhydrase. Furthermore, GFA, the characteristic marker for fibrous astroglia in higher vertebrates, was found specifically localized in the horizontal neurons of several teleost fish. The identity of the GFA antigens was qualified by immunochemical as well as cytological examinations. Furthermore, specific antisera to other intermediate filament proteins, including neurofilaments, validated and contrasted with the observations made with antisera to GFA. The presence of GFA in horizontal neurons of fish is widespread but not typical of all fish. These observations indicate an evolutionary constancy of retinal Müller glial cells. However, these results again focus attention on whether horizontal cells are truly neurons or rather represent an intermediate cell type that may prove useful in studying the evolution, ontogeny, and functional significance of the neuronal-glial phenotypic dichotomy.

Animals↗