The activities of aryl hydrocarbon hydroxylase (AHH) and glutathione s-transferase (GST) were measured in the lung tissues of lung cancer patients and patients without lung cancer. The results indicate that after controlling for age, sex, smoking, living conditions, occupational exposure, and medication history, the ratio of AHH to GST (AHH/GST) in the lung tissues of cancer patients was significantly higher than that in noncancer patients. This difference might suggest a genetic difference in benzo[a]pyrene (BP) activations between the two groups of patients, but whether there is a casual relation between AHH/GST and lung cancer is still a question. AHH/GST was high in patients who smoked. It is conceivable that smoking might increase the rate of BP activation. There was a positive correlation between AHH activity and the amount the lung cancer patients smoked, but the AHH activity was not affected by smoking in noncancer patients. The AHH activity of lung cancer patients seems more sensitive to induction by polycyclic aromatic hydrocarbons than that of noncancer patients. However, this suggestion should be further verified.

Adult↗

PubMed1988

[Changes in patterns of protein synthesis during retinoic acid induced-differentiation of F9-1 embryonal carcinoma cells].

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Animals↗

PubMed1988

[Effect of microinjection of monosodium glutamate into the obex area of the medulla on respiratory rhythm in rabbits].

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Animals↗

PubMed1988

[Postoperative radiation of retinoblastoma--report on 22 patients].

From July 1958 to December 1979, 22 patients with retinoblastoma were treated postoperatively by radiotherapy. All were proved by pathology. There were 12 stage I, 1 stage II, 8 stage III and 1 stage IV lesions. Radiation dose was more than 15 Gy and most of the patients received 40-50 Gy in 4-5 weeks. The overall cancer free 5 year survival rate was 55% (12/22). The 5 year survival rate of stage I patients was 75% (9/12), and that of stage III patients was 38% (3/8). None of the stage II and IV patients survived. Dose of 40-50 Gy/4-5 wk is considered to be optimal for control of the tumor. Dose higher than 60 Gy/6 wk could lead to retarded growth in the orbital and temporal bony structures if the patient survives for ten years or more.

Child↗

PubMed1987

Rapid sequencing of cloned DNA using a transposon for bidirectional priming: sequence of the Escherichia coli K-12 avtA gene.

A new approach to determining the sequence of cloned DNA is described. Unique regions near each end of the transposable element gamma-delta provide a pair of "portable" primer-specific sites for bidirectional sequencing by the dideoxy chain termination method. A set of gamma-delta insertions positioned about 200 bp apart over the entire cloned DNA allowed us to determine the sequence of both strands in a single parental plasmid without subcloning. The avtA (alanine-valine transaminase) gene of E. coli K-12 was sequenced by this approach. Surprisingly, gamma-delta insertions downstream of the coding region were found to significantly reduce avtA expression. We suggest that these nondisruptive insertions probably change the DNA topology and thereby alter gene expression.

Amino Acid Sequence↗

PubMed1987

Mouse histone H2A and H2B genes: four functional genes and a pseudogene undergoing gene conversion with a closely linked functional gene.

The sequence of five mouse histone genes, two H2a and three H2b genes on chromosome 13 has been determined. The three H2b genes all code for different proteins, each differing in two amino acids from the others. The H2b specific elements present 5' to H2b genes from other species are present in all three mouse H2b genes. All three H2b genes are expressed in the same relative amounts in three different mouse cell lines and fetal mice. The H2b gene with the H2b specific sequence closest to the TATAA sequence is expressed in the highest amount. One of the H2a genes lacks the first 9 amino acids, the promoter region, the last 3 amino acids and contains an altered 3' end sequence. Despite these multiple defects, there is only one nucleotide change between the two H2a genes from codon 9 to 126. This indicates that a recent gene conversion has occurred between these two genes. The similarity of the nucleotide sequences in the coding regions of mouse histone genes is probably due to gene conversion events targeted precisely at the coding region.

Animals↗

PubMed1987

Equilibrium and local stability in a logistic matrix model for age-structured populations.

A logistic matrix model for age-structured population dynamics is constructed. This model discretizes a continuous, density-dependent model with age structure, i.e. it is an extension of the logistic model to the case of age-dependence. We prove the existence and uniqueness of its equilibrium and give a necessary and sufficient condition for the local stability of the equilibrium.

Aging↗

PubMed1987

High frequency generalized transduction by miniMu plasmid phage.

Deletion derivatives of phage Mu which replicate as multicopy plasmids, and also transpose and package like Mu, have been developed for the in vivo cloning of bacterial genes. We show here that these miniMu plasmid phage are also efficient at generalized transduction and that both in vivo cloning and generalized transduction of a given gene can be accomplished in a single experiment.

Coliphages↗

PubMed1987

In-vivo studies of amphotericin B liposomes derived from proliposomes: effect of formulation on toxicity and tissue disposition of the drug in mice.

The repeat dose toxicity of various liposomal formulations containing amphotericin B has been determined in mice. In general, small liposomes (e.g. 100-150 nm) were found to be more toxic than their large counterparts (e.g. about 2000 nm). However, the repeat dose toxicity of small liposomes could be diminished substantially by the inclusion of sterol (i.e. ergosterol) into the liposomal membranes. Tissue accumulation studies of amphotericin B after repeat dosing may be a useful adjunct to formulation development.

Amphotericin B↗

PubMed1987

Cloning and characterization of the Escherichia coli K-12 alanine-valine transaminase (avtA) gene.

avtA, which encodes the alanine-valine transaminase, transaminase C, was cloned in vivo with high- and low-copy-number mini-Mu cloning vectors. The phenotype conferred by the cloned avtA+ gene usually depended upon the plasmid copy number; most high-copy-number avtA+ plasmids permitted isoleucine-requiring ilvE strains to grow in the absence of isoleucine (multicopy suppression), while low-copy-number avtA+ plasmids did not. avtA was mapped to a 1.25-kilobase segment by comparison of the restriction maps of 24 independent mini-Mu plasmids and then by gamma-delta (Tn1000) mutagenesis of a pBR322-avtA+ plasmid. The direction of transcription of avtA on the cloned fragment was determined with fusions to a promoterless lac gene.

Chromosome Mapping↗

PubMed1987

Growth and differentiation of transplanted rat embryos in intact, diabetic and hypophysectomized hosts: comparison with their growth in situ.

The objectives of this investigation were to evaluate the suitability of a transplant system for studying the endocrine control of growth and differentiation in rat embryonic/fetal tissues, and to gain information on the development of their hormone dependence. Whole 10-day-old rat embryos were transplanted under the kidney capsule of intact, hypophysectomized (Hx) or diabetic (Db) juvenile syngeneic female hosts, and grown there for 3, 6, 9 or 12 days. The wet weight, DNA and protein content of the transplants and of age-matched in situ embryos/fetuses were measured to assess their growth. The transplants in intact hosts increased more than 300-fold in all parameters during 12 days of incubation. However, this increase was only about 4% of the in situ growth. The severe impairment in growth occurred mainly during the first 3-day period when the transplants grew only 5% as much as the in situ embryos. Between days 13 and 22 of gestational age, the increment in transplant growth was 70% of that occurring in situ. Tissue differentiation of the transplants in intact hosts was essentially normal, although they grew as teratomas. Growth and differentiation of transplants in Db and Hx hosts were delayed or inhibited. This inhibition occurred as early as day 3 after transplantation and was corrected by appropriate hormone replacement therapy of the hosts. We conclude that rat embryos/fetuses develop a dependence on a growth hormone-dependent factor (possibly somatomedin) and/or insulin for growth before day 13 of development. This transplant system will be useful for studying other aspects of the control of growth and differentiation of rat embryos/fetuses between days 10 and 22 of gestation.

Animals↗

PubMed1987

Chronic sex steroid exposure increases mean plasma growth hormone concentration and pulse amplitude in men with isolated hypogonadotropic hypogonadism.

Sex steroid administration can increase the GH response to provocative stimuli, but the relationship of sex steroids to spontaneous GH secretion is still controversial. We sought to characterize the effect of sex steroids on the plasma GH concentration by examining the 24-h pattern of episodic GH secretion in nine previously untreated adult men with isolated hypogonadotropic hypogonadism before and during long term testosterone, gonadotropin, or pulsatile GnRH treatment. After chronic sex steroid exposure, the mean 24-h plasma GH level, mean GH pulse amplitude, and mean area under the curve of pulses were significantly increased compared to pretreatment values [3.2 +/- 1.8 ( +/- SD) vs. 1.8 +/- 1.2 ng/mL (P less than 0.01); 11.4 +/- 7.2 vs. 5.5 +/- 4.4 ng/mL (P less than 0.05); and 720 +/- 547 vs. 316 +/- 371 ng/mL X 20 min (P less than 0.05), respectively], while mean 24-h pre- and posttreatment GH pulse frequencies were indistinguishable (5.7 +/- 2.1 posttreatment vs. 5.0 +/- 3.2 pretreatment; P = NS). The mean posttreatment plasma somatomedin-C level also rose significantly during treatment (1.89 +/- 0.65 vs. 1.28 +/- 0.48 U/mL; P less than 0.01). We conclude that the increase in the mean plasma GH level during chronic sex steroid exposure is due mainly to augmentation of GH pulse amplitude, and that sex steroids probably increase spontaneous GH secretion.

Adult↗