Separation of RRBC-RFC and non-rosette forming cells (non-RFC) of guinea pig T-cell populations and their functional difference. 1. Response of RRBC-RFC and non-RFC to either Con-A or LPS.

Guinea pig lymph node cells suspension (LNC-O) was filtered through a glass wool column and the effluent (LNC-G) was further filtered through a nylon column. In this effluent (LNC-NE) about 30 per cent of the lymphocytes was identified as non-rosette forming cells (non-RFC). The non-RFC fraction was separated from LNC-NE fraction by Ficol-Conray specific gravity centrifugation or effluent cells reacted previously to rabbit red blood cells (RRBC). The upper layer after centrifugation, designated non-RFC fraction, was separated. In this fraction 96% of the cells were lymphocytes and about 95% of them were non-RFC, which lacked receptors for rabbit red blood cells (RRBC) or EAC and detectable surface immunoglobulin by conventional techniques. Though the response of the lymphocytes in the non-RFC fraction to mitogenic (Con-A, LPS) or antigenic stimulation was lower in comparison with that in RFC-rich fraction, the response of non-RFC to ConA exceeded the response to LPS. These facts suggest that at least a portion of the non-RFC may be cells from the T-cell line.     

Diagnosis of pseudomembranous colitis.

Twenty-eight patients with histologically proved pseudomembranous colitis have been seen in one hospital since July 1975. All patients with the disease had received antibiotics, six for infections not requiring operations; the other 22 cases all occurred after major surgery. All the patients had diarrhoea; six patients also had fever with clinical signs of sepsis, and three had abdominal pain thought to be due to anastomotic dehiscence after colonic resection. Pseudomembranous colitis was associated with white blood counts over 15 000/mm3 in 17 patients and albumin concentrations of less than 30 g/1 in 18. Pseudomembranous colitis was an incidental finding at necropsy in two of six patients who had not had an operation. Of the 22 patients who had had major surgery, nine died from this complication; in all except two of these cases the diagnosis was made only at necropsy. If pseudomembranous colitis is suspected on clinical grounds or if there is an unexplained complication after colorectal surgery repeat sigmoidoscopy and testing for faecal toxins should be carried out to establish the diagnosis so that prompt supportive treatment can be given.     

THE DIFFERENTIATING ABILITY OF RAT LENS EPITHELIAL CELLS IN CELL CULTURE

Dissociated cells of lens epithelia of adult rats were monolayerly cultured in vitro. After about 15–20 days' period of active cell growth, such characteristic structures that correspond to "lentoid bodies" described previously in chick cultures were formed. These structures consisted of elongated cells, ultrastructural profile of which was similar with lens fiber. The presence of gamma-crystallin, a marker molecule specific to mature lens fiber, was confirmed in these elongated cells by means of fluorescent antibody technique. The differentiation of lens fiber in vitro was also recognized in clones originating from single lens epithelial cells cultured at very low cell density.     

A new in vitro system for studying cell response to mechanical stimulation : Different effects of cyclic stretching and agitation on smooth muscle cell biosynthesis

An experimental model has been devised to permit morphologic and metabolic characterization of cells subjected to a range of cyclic mechanical stimuli similar to those which may prevail in blood vessel walls. A unique feature is the use of purified elastin membranes prepared from bovine aortas as extensible substrates for cell growth. Cells attached firmly to such membranes which could then be subjected to continuous stretching and relaxation or displacement without stretching by a motor coupled to a movable supporting frame. Various combinations of frequencies, amplitudes and rates of deformation have been used over extended periods with minimal fatigue or disruption of the elastin substrate. The effects of cyclic stretching on [¹⁴C]proline incorporation into protein and collagen and [³H]thymidine incorporation into DNA by rabbit aortic smooth muscle cells were distinct from those attributable to agitation without stretching, indicating that cells responded differently to these modes of stimulation. Increases in rate of protein or DNA synthesis induced by stretching were just as marked after 48 h of stimulation as they were at the outset of an experimental period. Since the system permits observations of cell response to independently variable components of pulsatile stress over extended periods and under a variety of culture conditions, it may be expected to provide new data concerning the interaction of mechanical with hormonal and genetic factors in the elaboration of connective tissue components.     

Isolation and characterization of lipopolysaccharides from cell walls of blue-green algae of the genus Phormidium.

Lipopolysaccharide (LPS) fractions were isolated from three species of blue-green algae of the genus Phormidium, namely, P. africanum, P. laminosum, and P. uncinatum, by using a phenol-water procedure followed by exhaustive extraction with ammonium oxalate. The materials obtained were shown to be closely related biochemically. Nearly 60% of the LPS consisted of the polysaccharides galactose, glucose, mannose, xylose, arabinose, and rhamnose and an unidentified, fast-moving sugar residue. In addition, glucosamine, galactosamine, and 2-keto-3-deoxyoctonate were detected. Oleic, stearic, and palmitic acids were found in the hydrolysate of the lipid component, which averaged 1.5% of the LPS. Concomitantly, the protein component (7 to 20%) was shown to contain the following amino acids: aspartic acid, threonine, serine glutamic acid, proline, glycine, alanine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine, and arginine. Whole cells, as well as the LPS, of Phormidium possessed antigenic properties.     

Purification of lipase from Chromobacterium viscosum by chromatography on palmitoyl cellulose.

Palmitoyl cellulose was used to adsorb the extracellular lipase [triacylglycerol acyl-hydrolase EC 3.1.1.3] of Chromobacterium viscosum from crude enzyme solution, and the adsorbed enzyme was eluted with a suitable detergent, such as Adekatol 45-S-8 or Triton X-100. The enzyme was then purified by chromatography on a palmitoylated gauze column with an overall recovery of 71% and an increase in the specific activity of 11-fold from the supernatant fluid of bacterial cultures. Further purification procedures included fractionation with acetone, and chromatography on Sephadex G-150 and G-75 columns. Two isoenzymes were obtained, each in a homogeneous state on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis: one had a molecular weight of 120,000 and pI of 3.7 and the other a molecular weight of 30,000 with a pI of 7.3.