Improved Culture Techniques Research Articles

Effects of Sulphur Dioxide and Fluoride on Ascospore Germination of Several Lichens

AbstractThe effects of fluoride and sulphur dioxide on the germination of ascospores of Lecanora conizaeoides, Xanthoria parietina, Physconia distorta and Peltigera canina were studied under controlled conditions. The two pollutants (H2SO3 and NaF) were dissolved in the culture medium. An improved culture technique permitted a high percentage germination (90° 0) of P. canina spores. Peltigera canina spores had the highest sensitivity to SO2 (no germination at 500 UM H2SO3). Lecanora conizaeoides spores were almost insensitive to each of the two studied pollutants (30°0 spore germination at 1000 UM H2SO3 or NaF). However, simultaneous exposure to 1000 UM H2SO3 and 1000 UM NaF resulted in no germination, indicating a synergistic effect of these products.

Improved tissue culture technique for production of poorly replicating human immunodeficiency virus strains

We present an improved culture technique for propagation of human immunodeficiency virus (HIV) strains that grow slowly, yield low reverse transcriptase activity and can be transmitted poorly, if at all, to cell lines. By using the Jurkat-tat III cell line 29 (of 30) of these slow/low HIV strains, including one West African strain, could be shown to replicate over a period of several weeks.

Monolayer-forming islet cell culture from neonatal pig pancreas: Using sequential treatment with EDTA-dispase and monoiodoacetic acid for preparation and purification.

A new method for the preparation and purification of a monolayer-forming islet cell culture from the neonatal pig pancreas is described. Single cell preparations of the pig pancreas were obtained by gently stirring the chopped pancreases in a medium containing sequential EDTA-dipase. Exposure of the cells to monoiodoacetic acid (10 micron) and BSA-gradient resulted in improved preparation, highly enriched in the endocrine cells. The cells were maintained in tissue culture medium 199 containing 5.5 mM D-glucose, with or without 0.1 mM 3-isobutyl-1-methylxanthine, or 16.7 mM D-glucose and 20% fetal calf serum. During a 6-day culture period, many small cell aggregates appeared in the media. The cell clusters attached to the bottom of the dish and formed monolayers. Provocative stimulation and radioimmunoassay for insulin showed the existence of numerous and viable B cells in the cell clusters. The other three types of islet cells were also demonstrated immunohistochemically in the cell cluster. It is concluded that this improved culture technique provides a useful tool for morphological and biochemical studies of islet cells and a potential source of material for transplantation of B-cells from the pancreas.

Tissue culture of human fetal pancreas. Development and function of B-cells in vitro and transplantation of explants to nude mice.

The present study evaluates the development and function of human fetal B-cells in vitro with a view to using such cells in future attempts for transplantation of human fetal pancreas to diabetic patients. A method previously described in our laboratory for preparing islets in vitro from the fetal rat pancreas has been applied and modified for use with human fetal pancreas. Pancreatic glands of different gestational ages were obtained from 37 consecutive prostaglandin-induced abortions. After a mild collagenase treatment, the partially disintegrated tissue was maintained in culture for 7 days in tissue culture medium RPMI 1640 plus 20% fetal calf serum to permit cell attachment and out-growth of endocrine cells. In 17 of the 37 consecutively cultured fetal pancreatic glands, islet-like cell clusters were formed. The 20 remaining glands were lost because of either bacterial contamination or lack of viability already before dissection had occurred. Sections of the newly formed cell clusters revealed well-preserved pancreatic cells showing frequent mitotic figures. The tissue exhibited a high rate of (pro)insulin biosynthesis and a modest insulin response to secretory stimuli, suggesting that the mechanism of glucose regulation by the fetal B-cells is not yet fully developed. Electron micrographs showed a large number of granule-containing cells, some of which were identified as B-cells. In nine cases, harvested cell clusters were implanted beneath the kidney capsule of nude mice. When these animals were killed after 2 mo, seven mice showed a considerable growth of the grafts with numerous islet-like structures containing insulin- and glucagon-positive cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Leishmania braziliensis in the Panamanian two-toed sloth, Choloepus hoffmanni.

A total of 498 two-toed sloths, Choloepus hoffmanni, collected in central Panama was examined for Leishmania braziliensis over a 10-year period. Isolations of the parasite from 96 (19.3%) of the animals were confirmed by culture and inoculation of golden hamsters. Improved culture techniques developed toward the end of the study assisted in determining a greater prevalence of the disease. Infectins were completely cryptic in all animals, and the parasite was isolated from skin, blood, liver, spleen, bone marrow and lung tissues. Sloths maintained under seminatural conditions remained infected up to 23 months, the longest period of survival. This edentate, considered the principal reservoir host of L. braziliensis in Panama, showed infection rates from 0-59.4% in various communities, which appeared to correlate with the parasite prevalence in the indigenous human populations.

10 - Characteristics of Amniotic Fluid Cells In Vitro and Attempts to Improve Culture Techniques

10 - Characteristics of Amniotic Fluid Cells In Vitro and Attempts to Improve Culture Techniques

Anaerobic bacterium in renal transplantation

Renal allograft recipients were studied prospectively utilizing improved culture techniques to investigate anaerobic bacteriuria. The study population was compared with a population of patients with chronic renal insufficiency and end stage renal disease. The over-all incidence of anaerobic urinary tract infection was 7.5 per cent while the over-all incidence of aerobic urinary tract infection was 23.5 per cent. Patients with cadaver renal transplants during the early postoperative period had the highest incidence of both anaerobic (42.9 per cent) and aerobic (71.4 per cent) urinary tract infection of all groups. The potential association between significant anaerobic bacteriuria during the first postoperative month and poor prognosis for cadaver renal allografts merits further investigation.

An improved technique of preparing bone-marrow specimens for cytogenetic analysis

Sixty-six bone-marrow specimens, derived from patients with hematological and nonhematological disorders, were processed for cytogenetic analysis. Modifications of various parameters of the standard (direct) culture procedure were investigated and the quality of the preparations determined. As a result of these experiments, an improved culture technique was developed that yielded significantly better quality chromosome preparations. This method is based on a short incubation (25-min) of the bone-marrow specimen, immediately following aspiration, in a solution containing both hypotonic KCl and colcemid and completely omits the use of tissue culture medium.

Comparison of the routine guinea-pig test and improved culture techniques in the diagnosis of tuberculosis (author's transl)

Comparison of the routine guinea-pig test and improved culture techniques in the diagnosis of tuberculosis (author's transl)

Anaerobic bacteria of the gastrointestinal flora and their occurrence in clinical infections.

Within the last few years, knowledge concerning anaerobic bacteria of man and other monogastric animals has increased and changed a great deal. With the development of improved culture techniques for the cultivation of the more sensitive anaerobes, it has become possible to study more effectively the anaerobic flora of man and other animals. Studies carried out with these methods have shown that no area of the gastrointestinal tract is sterile, that the predominant kinds of bacteria in the different areas of the tract are not the same, that the bacteria in the tract are metabolically active, and that the same species of anaerobic bacteria are also found, rather frequently, in infected tissue.

CHANGING CONCEPTS IN TUBERCULOSIS. THE ANONYMOUS MYCOBACTERIA.

Since Koch's classic investigations in 1882 established Mycobacterium tuberculosis as the causative agent of mammalian tuberculosis, there have been remarkably few changes in the concepts of tuberculosis or tuberculosis bacteriology. In recent years, with the increased use of improved culture techniques as a diagnostic aid, acid-fast bacilli other than the well-known human, bovine, and avian tubercle bacilli are being isolated from clinical material with increasing frequency. Recent case reports have definitely shown these microorganisms to be etiological agents of a human tuberculosis-like disease. The term atypical has been used to describe these organisms, but should be discontinued because this term implies that the two mammalian varieties of tubercle bacilli are the typical organisms of reference. Furthermore, these mycobacteria are apparently not mutants or strains or tubercle bacilli but, rather, completely distinct organisms. Since many of these mycobacteria are capable of producing disease in man, they deserve taxonomic classification and