The Effect of End Group Modification on the Transparency of Vinyl Addition Norbornene Polymers at 193 nm

Summary: Homopolymers of a bis‐trifluorocarbinol substituted norbornene ( 1 ) (α,α‐bis(trifluoromethyl)bicyclo[2.2.1]hept‐5‐ene‐2‐ethanol or HFANB) and copolymers of 1 with t‐butyl ester of 5‐carboxylic acid ( 2 , t‐BuEsNB) were produced using palladium catalysts and olefinic chain transfer agents such as 1‐hexene and ethylene to control molecular weight. However, these low‐molecular‐weight polymers exhibited relatively low optical transparencies at 193 nm. In fact, the opacity (measured as optical densities in absorbance units per micron) of thin films of these homo‐ and co‐polymers was inversely proportional to their molecular weight. This relationship is consistent with an end group contribution to the film opacity. Spectroscopic analysis of these polymers by ¹H NMR and MALDI‐TOF MS confirmed that 1‐hexene and ethylene chain transfer agents generated olefin‐terminated vinyl addition polymers. The olefinic end group contribution to optical density can be eliminated by appropriate chemical modification. Both epoxidation and hydrogenation of the polymer olefinic end groups generated very low optical density materials, independent of molecular weight, that are suitable as 193‐nm photoresist binder resins.

End group modification of vinyl and hexenyl‐terminated homopolymers of 1 by epoxidation or hydrogenation.     

Phenotypic analysis of a CD2- CD3+ T cell receptor gamma delta lymphocyte subset

We have identified, in a patient with atopic dermatitis, a consistent population of peripheral blood lymphocytes expressing a CD3+ gamma/delta TCR complex, while being unreactive with CD2. Further immunofluorescence studies showed that these cells almost completely co-express CD29 and CD45RA and have high membrane levels of CD11a compared to the alpha/beta TCR T cells. Neither a genetic influence nor an acute or reactivated herpesvirus infection were found to be related to the expanded gamma/delta T-cell subpopulation. Our data confirm the previous observations regarding the presence in the peripheral blood of an expanded gamma/delta TCR, CD2- subset and show that these cells have a peculiar phenotypic profile. The reasons for this expansion are, however, still unknown.     

Sister chromatid exchange and proliferation pattern in lymphocytes from newborns, elderly subjects and in premature aging syndromes

Sister chromatid exchange (SCE) frequency and cell proliferation were examined in lymphocyte cultures from a group of newborns, a group of elderly subjects and from patients with syndromes who exhibit progeriform characteristics (progeria, Cockayne syndrome, Rothmund-Thomson syndrome and Christ-Siemens-Touraine syndrome) by using the bromodeoxyuridine incorporation differential staining technique. We observed a significantly increase in basal SCE frequency and a less intensive cell proliferation in cultures from elderly subjects than from newborns, as shown by the significant increase in percentage of cells in first generation simultaneous with a reduction of cells in more advanced generations. Lymphocyte cultures from each one of the patients studied also showed a decreased cell proliferation in relation to their respective control and to newborn cultures. Each of these syndromes showed higher baseline SCE levels than the control and than the newborn and elderly groups. Only the patient with progeria showed values similar to those for the elderly group. Thus, in addition to showing clinical characteristics similar to those observed during the normal aging process, these progeriform syndromes also show cytogenetic characteristics similar to those of older individuals.     

Lymphoid and non-lymphoid cells in the adenoid of children with otitis media with effusion: a comparative study

We characterized on immuno- and enzymecytochemical level the lymphoid and non-lymphoid cells in the adenoid of children with upper respiratory tract infections (URI) and otitis media with effusion (OME) and compared these with the adenoid of children with URI without OME and with the adenoid of 'healthy' children and adults. Besides macrophages and dendritic cells we also showed the presence of MHC class II positive, ciliated, epithelial cells. These non-lymphoid cells were present in all adenoids. However, their number was less than 1% of all cells. We found no difference in lymphocyte subsets from children with URI + OME compared with those from children with URI alone. These two groups showed a significant decrease of CD8-positive (suppressor/cytotoxic) cells and a slight increase in CD22-positive B cells in comparison to 'healthy' children. No difference was found in percentages of CD4-positive (helper/inducer) cells. The localization of the lymphoid subsets in adenoids of children with URI and/or OME did not differ from those of 'healthy' children and adults.     

Insulin-specific T cell hybridomas derived from (H-2b x H-2k)F1 mice preferably employ F1-unique restriction elements for antigen recognition

T cell hybridomas of (B10 X B10.BR)F1 genotype with reactivity to bovine insulin (BI) were established to analyze the restriction and antigen fine specificity of (H-2b X H-2k)F1 T cells towards BI. Our data indicate a focusing of the response on two epitopes on the insulin molecule, the A chain loop determinant comprising amino acids A8 and A10, as well as the glutamic acid residue in position 4 of the A chain. Both were recognized either separately or in conjunction. Unexpectedly, the T cell hybridomas exhibited a marked preference for recognizing insulin in the context of F1-unique restriction elements of Ab alpha Ak beta type rather than parental high-responder I-Ab molecules. Analysis of the response of primed lymph node T cells of (B10 X B10.BR)F1 mice towards BI corroborated the finding of a preponderant corecognition of F1-unique I-A molecules.     

Production of fimbrial adhesins K99 and F41 by enterotoxigenic Escherichia coli as a function of growth-rate domain.

The production of fimbrial adhesins K99 and F41 by enterotoxigenic Escherichia coli has been measured in steady-state chemostat experiments at various specific growth rates (microseconds) and in a recycling fermentor across a range of mu values falling to less than 0.004 h-1. It has been demonstrated that the production of K99 and F41 fimbriae is correlated with mu both in aerobic and anaerobic chemostat experiments. A significant production of fimbriae was only detected at mu values higher than 0.2 h-1. This behavior was further examined by culturing the bacteria in a recycling fermentor with complete biomass retention. It could be shown that the production of K99 and F41 fimbriae only occurred during balanced growth, with a high biomass yield at mu values higher than 0.04 h-1 corresponding to mass doubling times (td) of less than 17 h. The production of both fimbriae halted during balanced growth with a lower biomass yield (at mu values between 0.012 and 0.04 h-1 corresponding to td values between 17 and 58 h) and unbalanced stringent growth (at mu values lower than 0.012 h-1 or td values higher than 58 h). The external pH of the medium greatly influenced the production of both K99 and F41 fimbriae. At pH values lower than 7, the production of fimbriae was strongly inhibited. Also, at pH values higher than 7, a decrease in production was observed. The consequences of the observed phenomena for the pathogenic behavior of this E. coli strain are discussed.     

Influence of human leukocyte interferon on IgG on the replication of herpes simplex virus in nervous tissue in vitro.

Herpes simplex virus type 1 (HSV-1) replicated productively in rabbit and guinea pig ganglia and nerve organ cultures when inoculated in high titres. Treatment with IgG 20 hr before and 48 hr after infection produced a delay of 4 to 7 days in the recovery of HSV-1 by the method of co-cultivation. The same result was obtained when IgG was combined with human leukocyte interferon. There was no difference in the period up to HSV recovery between the groups treated with interferon alone and the HSV control. Morphological evidence by light and electron microscopy of viral productive infection was obtained in all the cell types of nervous tissues infected in vitro.     

TT virus infection in human immunodeficiency virus type 1 infected mothers and their infants

Serum TT virus (TTV) DNA was determined in 83 human immunodeficiency virus type 1 (HIV 1) infected mothers [46 intravenous drug user and 37 non-intravenous drug user women] and their infants. Twenty-nine (34.9%) mothers were TTV infected. Infection was more frequent among intravenous drug user than non-intravenous drug user mothers [21/46 (45.6%) vs. 8/37 (21.6%); relative risk (RR): 2.1; 95% confidence limits (95% CL): 1.1-4.2; P = 0.023] and among intravenous drug users who carried on injecting than in those who had given it up [10/14 (71.4%) vs. 11/32 (34.3%); RR: 2.1 (95%CL: 1.2-3.7); P = 0. 021]. Infection was not related to age, CD4-positive T-lymphocyte counts, HIV 1 load, hepatitis B (HBV), G/GB-C (GBV-C/HGV), C (HCV) virus exposure. Eight (27.5%) infants born to TTV infected (but none of those born to TTV uninfected) mothers were TTV infected at a median age of 1.5 (range: 0.6-2.8) months. Infants born by vaginal/emergency caesarean delivery were more frequently infected than those born by elective caesarean delivery [7/16 (43.7%) vs. 1/13 (7.6%); RR: 2.1; 95%CL: 1.2-3.5; P = 0.033]. Infection in infants was not related to maternal CD4-positive T-lymphocyte counts, HIV 1 load, and HIV 1, HBV, GBV-C/HGV, or HCV transmission. No infant became TTV infected thereafter. No TTV infected child [follow-up: 31 (median; range: 6-60) months] showed signs of liver disease; five infants cleared TTV DNA after 22 (median; range: 6-60) months. TTV infection in HIV 1 infected women is prevalently related to intravenous drug user. The findings suggest that infants may acquire TTV at birth. Infection may persist without evident liver disease.     

Long-term regeneration of fast and slow murine skeletal muscles after induced injury by ACL myotoxin isolated from Agkistrodon contortrix laticinctus (broad-banded copperhead) venom

The aim of the present work was to analyze the regenerated muscle types I and II fibers of the soleus and gastrocnemius muscles of mice, 8 months after damage induced by ACL myotoxin (ACLMT). Animals received 5 mg/kg of ACLMT into the subcutaneous lateral region of the right hind limb, near the Achilles tendon; contralateral muscles received saline. Longitudinal and cross sections (10 microm) of frozen muscle tissue were evaluated. Eight months after ACLMT injection, both muscle types I and II fibers of soleus and gastrocnemius muscles still showed centralized nuclei and small regenerated fibers. Compared with the left muscle, the incidence of type I fibers increased in the right muscle (21% +/- 03% versus 12% +/- 06%, P = 0.009), whereas type II fibers decreased (78% +/- 02% versus 88% +/- 06%, P = 0.01). The incidence of type IIC fibers was normal. These results confirm that ACLMT induced muscle type fiber transformation from type II to type I, through type IIC. The area analysis of types I and II fibers of the gastrocnemius revealed that injured right muscles have a higher percentage of small fibers in both types I and II fibers (0-1,500 microm2) than left muscles, which have larger normal type I and II fibers (1,500-3,500 microm2). These results indicate that ACLMT can be used as an excellent model to study the rearrangement of motor units and the transformation of muscle fiber types during regeneration.