The role of disorder in phase transformations in PTFE

The transformation of PTFE from phase II to phase IV at 19°C and atmospheric pressure has been investigated using wide angle X-ray diffraction. Diffraction patterns were taken as a function of temperature. The integrated intensity of an equatorial peak present only in phase II was used to monitor the extent of the transformation. Peaks on the second and fifth layer lines were used to determine the effect of transformation and/or disorder. Integrated intensities on these three layer lines were shown to decrease differently with increasing temperature. The decrease in intensity on the second and fifth layer lines could be described in terms of a model comprising the initial integrated intensity, fraction transformed and the amount of rotational disorder present. Molecular modeling also was used to investigate the transformation. A commercially available force field was modified to represent the equilibrium solid state of PTFE. The modified force field was used to examine aspects of the transformation including the influence of neighboring molecules on the molecular conformation.     

Severe combined immunodeficiency with cartilage-hair hypoplasa: in vitro response to thymosin and attempted reconstitution

The present report describes an infant with severe combined immunodeficiency and cartilage-hair hypoplasia whose lymphocytes responded to thymosin in vitro. Immunologic evaluation was undertaken at 4 1/2 months of age following a history of recurrent severe infection. Family history included three cousins who died in early infancy, one from streptococcal meningitis and pneumonia, one from generalized varicella, and another from reticuloendotheliosis. Quantitative immunoglobulins were markedly depressed: IgG 141, IgA 0, and IgM 24 mg/100 ml. There was an absolute lymphopenia, multiple skin tests were negative, and in vitro lymphocyte responses to mitogens and antigens were depressed. Spontaneous E rosette determinations were 21% compared with control values of 65.7%. Erythrocyte adenosine deaminase (ADA) activity was normal. The patient's E rosette formation increased in the presence of thymosin, fraction 5, reaching a maximum of 56% with a concentration of 500 mug thymosin. Blastogenic responses to phytohemagglutinin also increased in the presence of thymosin. Transplantation of 24-week fetal thymus in Millipore diffusion chambers and subsequently transplantation of 18-week fetal thymus by intraperitoneal injection was accomplished. E rosettes increased to 35-40% and blastogenic responses to mitogens increased. Eight days after the second transplant the patient underwent a mild graft vs. host reaction which subsided after 1 week and mitogen blastogenic responses again increased to 5-8 times previous values, but still well below control ranges. Repeated episodes of pulmonary infection ensued, cor pulmonale resulted, and the clinical course was relentlessly downhill with the patient expiring from respiratory failure 5 months after transplantation.     

Subgroup F adenovirus growth in foetal intestinal organ cultures

An in vitro foetal intestinal organ culture system was employed to determine the permissiveness of human intestinal cells for subgroup F adenovirus infection. Ad40 and Ad41 growth, monitored through group-specific hexon antigen production, was poor in comparison to that of Ad2 in these cultures, further demonstrating their fastidious nature in most human cells. The low growth capability of these viruses in culture, in relation to their association with gastrointestinal disease is discussed.