Flow cytometric quantification of rat spermatogenic cells after hypophysectomy and gonadotropin treatment

DNA flow cytometry was evaluated as a tool to analyze stage-specific changes that occur in absolute cell numbers in the testes. Hypophysectomy was selected as a model system for perturbing testicular cell types, since the cytological sequelae of this treatment post-hypophysectomy in the rat are well documented in the literature. Rat spermatogenic cells in stages II-V, VII, and IX-XIII of the seminiferous epithelial cycle (as defined by Leblond and Clermont, 1952) were quantified in numbers per standard length of seminiferous tubule by DNA flow cytometry after hypophysectomy and subsequent gonadotropin treatment. In agreement with previous histological studies, we found that acrosome- and maturation-phase spermatids disappeared from the seminiferous epithelium after 17 days post-hypophysectomy, whereas meiosis and early spermiogenesis continued at least 164 days. The number of meiotic cells and round spermatids gradually decreased after hypophysectomy. Changes were observed as early as Day 6 post-hypophysectomy. Treatment with human chorionic gonadotropin (hCG) alone maintained most cell numbers within normal limits, and follicle-stimulating hormone (FSH) was needed in addition to hCG to maintain the normal number of cells with the amount of DNA contained in primary spermatocytes and spermatogonia in G2/M-phase (4C) in stages IX-XIII and elongated spermatids (1C') in stages II-V of the epithelial cycle. The absolute numbers of spermatogenic cells at different phases of maturation provide a useful reference for quantitative studies of spermatogenesis. Pathological changes in the seminiferous epithelium can be detected and quantified by DNA flow cytometry.     

Studies on new,centrally active and reversible acetylcholinesterase inhibitors

We have synthesized the tertiary amines of pyridostigmine and neostigmine, 3-pyridinol dimethylcarbamate (norpyridostigmine) and 3-dimethylaminophenol dimethylcarbamate (norneostigmine) respectively, and we have tested their abilities to cross the blood-brain barrier and inhibit mouse brainAChE activity. The in vivo inhibition of AChE activity by norpyridostigmine reaches 72% at 10 minutes which is comparable to that seen with physostigmine (73% at 10 minutes). Inhibition by norneostigmine is less effective (50% at 10 minutes) and approaches that obtained with tetrahydroaminoacridine (57% at 10 minutes). These data show that both norpyridostigmine and norneostigmine cross the blood-brain barrier and that they are effective inhibitors of mouse brain AChE activity. These drugs could be useful in the treatment of memory, impairment associated with Alzheimer's disease, and other memory disorders.     

Serum-free culture of primitive murine hemopoietic colony-forming cells

We report the effect of four sources of hemopoietic growth factors, alone or in combination, on colony growth in serum-free cultures of bone marrow from normal mice or marrow from mice pre-treated with 5-fluorouracil (5-FU-bm). The four supplements were: mouse spleen conditioned medium (SCM, a source of multi-lineage colony-stimulating activity, multi-CSA), human placental conditioned medium (HPCM, a source of synergistic activity), pregnant mouse uterus extract (PMUE, a source of M-CSA) and erythropoietin (Epo). First, in cultures of normal marrow, only PMUE and SCM induced significant colony growth when added alone. The majority of those colonies contained granulocytes and macrophages (myeloid colonies). In Epo-supplemented cultures, only SCM supported the growth of erythroid bursts and mixed erythroid-myeloid colonies. HPCM thus appears to be a poor source of multi-CSA. Second, in cultures of 5-FU-bm, few colonies developed if any of the above supplements were added alone. Only SCM + Epo together stimulated the formation of a low number of very large, mixed erythroid/myeloid/megakaryocyte colonies. HPCM, but not SCM, synergized with PMUE to augment myeloid colony numbers. Hence, SCM appears to be a poor source of synergistic activity (SA). In cultures of 5-FU-bm already supplemented with HPCM + PMUE, the addition of Epo did not change total colony numbers but did induce erythroid differentiation in one third of the colonies present. These data suggest that multi-CSA and SA may be expressed by different factors and that 5-FU pre-treated marrow contains: a population of primitive multipotential progenitors which form large, mixed colonies in the presence of SCM + Epo, and a larger Epo-sensitive population which also requires HPCM + PMUE to form mixed colonies.     

The repA2 gene of the plasmid R100.1 encodes a represser of plasmid replication

We have constructed two miniplasmids, derived from the resistance plasmid R100.1. In one of these plasmids 400 bp of R100.1 DNA have been replaced by DNA from the transposon Tn1000 (gamma-delta). This substitution removes the amino-terminal end of the repA2 coding sequence of R100.1 and results in an increased copy number of the plasmid carrying the substitution. The copy number of the substituted plasmid is reduced to normal levels in the presence of R100.1. The repA2 gene thus encodes a trans-acting repressor function involved in the control of plasmid replication.     

Selective Coronary Angiography Using a Percutaneous Femoral Technique

Successful use, in 650 patients over a period of two years, of a percutaneous femoral technique of selective coronary angiography is described. This technique is carried out with the use of mouldable, manually preshaped polyethylene catheters. Preparation of the material and the different steps of the technique are discussed. Excellent flexibility and plastic memory of this catheter material allow easy, rapid and consistent percutaneous insertion and removal of catheters and intubation of the coronary arteries.     

Criteria for Internal Mammary Artery Implantation Based on Cine Coronary Arteriography

Preoperative coronary arteriograms were correlated, in a group of 50 patients, with left internal mammary angiograms obtained from 11 to 32 months, with a mean of 17 months, after mammary artery implantation. In all patients in whom the internal mammary artery was patent and considered functional with good angiographic opacification of the anterior descending coronary artery, the preoperative coronary angiogram showed total or subtotal obstruction of the latter vessel, with indirect evidence of decreased flow and pressure distal to the obstruction. This evidence was provided by the presence of a collateral circulation or, in a few cases of subtotal obstruction, delayed opacification of the vessel distal to the obstruction.In patients in whom the internal mammary artery was patent but showed no anastomotic connection with the anterior descending coronary artery or only opacification of small coronary branches, the degree of coronary obstruction was, in most cases, less than 90% of the lumen of the coronary artery in the absence of any collateral circulation or delayed opacification of the vessel distal to the obstruction.Occlusion of the internal mammary artery was seen as often in the presence of total or subtotal obstructions as with lesser degrees of anterior descending coronary artery obstruction, and is believed unrelated to the degree of pre-existing coronary artery disease.Successful internal mammary artery implantation can be related to specific coronary angiographic patterns recognizable before operation; these may serve as reliable criteria for the selection of patients.     

HIGH-RESOLUTION AUTORADIOGAPHY : II. The Problem of Resolution

The resolution obtainable in electron microscopic autoradiographs, using a photographic emulsion consisting of a monolayer of silver bromide crystals, was investigated theoretically and experimentally. The expected distribution of exposed crystals around a point source was calculated from the geometry of the preparation and from the range distribution of the beta particles emitted by tritium. From such a distribution an autoradiographic resolution of the order of 1000 A can be predicted. From the point source distribution, the expected distribution of grains around bacteriophages labeled with tritium was calculated. This distribution was also measured experimentally in electron microscopic autoradiographs of bacteriophages T-2 labeled with thymidine-H³. The two distributions agreed closely. It was also verified, using the nuclear region in thin cross-sections of Bacillus subtilis labeled with thymidine-H³, that resolutions of the same order were obtained for extended sources. It was concluded that an autoradiographic resolution of 1000 A could be achieved with a presently available commercial emulsion, although emulsions with finer grains might be desirable in some circumstances.