Trisomy of the short arm of chromosome 8: Association with translocation between chromosomes 8 and 22 46,XY,22−,t(8p22q)+

The case of a retarded child with trisomy of the short arm of chromosome 8 associated with translocation between the short arm of chromosome 8 and the long arm of chromosome 22 is reported. Balanced translocation involving the same chromosomes was present in the mother and brother of the propositus. The specific chromosomes involved in the abnormality in this family were identified by use of fluorescence microscopy with quinacrine mustard staining, autoradiography and Giemsa banding. This appears to be the first case report of this anomaly, although trisomy of the short arm of chromosome 9 has been reported previously.     

Advanced 1H Solid‐State NMR Spectroscopy on Hydrogels, 1

Summary: The nature of the pH dependent collapse of poly(methacrylic acid) (PMAA) hydrogels is investigated using recent ¹H solid‐state NMR methods. In aqueous solution, PMAA changes from an expanded conformation at high pHs to a compact contracted form at low pHs, where hydrogen bonds play a central role. In solid‐state ¹H NMR spectra, recorded under fast magic angle spinning (MAS), dried PMAA samples previously collapsed at low pHs show characteristic signals in the spectral region of the carboxylic acid protons. With the aid of 2D ¹H‐¹H double‐quantum (DQ) MAS NMR spectra, three signals can be distinguished at 8, 10.5 and 12.5 ppm, which are attributed to free carboxylic groups and two different types of hydrogen bonded forms, respectively. The 12.5 ppm signal arises from the hydrogen bond with the shortest H? H distance, corresponding to the form that is most stable with respect to increasing temperature and pH. The weaker hydrogen‐bonded form (with a signal at 10.5 ppm) requires a slightly lower pH, while the free acid signal (at 8 ppm) emerges under the most acidic medium. Moreover, the stabilities of the hydrogen‐bonded carboxylic acid dimers can be inferred from the proton‐proton distances within the dimers, i.e. (275 ± 5) pm and (295 ± 15) pm for the protons at 12.5 and 10.5 ppm, respectively, which are determined by means of DQ MAS sideband patterns. Both the stability of the hydrogen bonds and the acidity of the protons may be related to the stereochemistry and the conformation of the PMAA chains.

     

Isolation of human immunodeficiency virus (HIV) from plasma during primary HIV infection

Human immunodeficiency virus (HIV) has been isolated from plasma in 6 of 7 patients showing clinical symptoms of a primary HIV infection. Parallel cultures from peripheral blood mononuclear cells (PBMC) yielded virus in 5 patients. In one case, virus could only be isolated from the cerebrospinal fluid but not from peripheral blood. Detectable viremia was transient and preceded the appearance of HIV specific antibodies. After cessation of acute symptoms, the frequency of HIV isolations was similar to that of asymptomatic carriers (23 and 26%, respectively). The role of the immune response in terminating detectable viremia remains to be established.     

Effect of treatment with octreotide on the morphology of growth hormone—secreting pituitary adenomas: Study of 24 cases

Twenty-four acromegalic patients were treated with octreotide subcutaneously for periods of 3 to 6 weeks (group I, 12 cases) or 6 months (group II, 12 cases) before transsphenoidal surgery. Radiological studies performed in 19 patients before and at the end of this treatment period revealed no changes in 8 cases. In 8 other cases, a slight reduction in tumorsize was observed, and in 3 cases an important shrinkage was documented. At surgery, the adenomatous tissue appeared softer than in nonpretreated patients, facilitating the operation. Pathological examination revealed widening of perivascular spaces with accumulation of fibrous tissue and more crinophagy than in nonpretreated patients but failed to reveal morphologically pronounced cell involution as observed in prolactin-producing adenomas treated with dopamine agonists. No significant difference in frequency or extent of cellular changes was noted between the two groups. These morphological findings seem to be more consistent with a functional inhibition of growth hormone release than with cellular alterations induced by octreotide.     

Copolymers with soft and hard segments based on 2,2-dimethyltrimethylene carbonate and ε-caprolactone

Thermoplastic elastomers with ABA-block structure, A representing the hard segment and B the soft segment, were prepared by ring-opening polymerization from 2,2-dimethyltrimethylene carbonate (DTC, 1 ) and ε-caprolactone (ECL, 2 ) as monomers. Typical anionic initiators, viz. the dilithium salt of hydroxytelechelic poly(ethylene oxide) 200 ( 4 ) and of polytetrahydrofuran 1000 ( 5 ) and as an insertion initiator the bis(diethylaluminium) salt of triethylene glycol were used. The soft block is formed by a sequence of random (or tapered) structure comprising equimolar amounts of the two monomers and obtained by simultaneous polymerization of DTC and ECL. The hard blocks consist of highly crystalline poly(2,2-dimethyltrimethylene carbonate) sequences. The thermal properties of the polymers depend on the sequence length, the content of heterodiads in the soft block and the thermal history of the samples. Copolymer films with short end blocks and high content of heterodiads show rubber-elastic properties at normal conditions.     

CD23 and CD21 function as adhesion molecules in homotypic aggregation of human B lymphocytes

We have previously found that interleukin-4 and CD40 monoclonal antibodies (mAb) are strong potentiatiors of homotypic B cell aggregation which is dependent on LFA-1. We show here that CD23 mAb were also able to inhibit aggregation to a similar extent as LFA-1 antibodies. This inhibition was restricted to the MHM6 epitope of CD23 and antibodies to other epitopes [Epstein-Barr virus (EBV) CS-1, EBV CS-2, EBV CS-5 and mAb 25] or occupation of the Fc-binding site by IgE had no or a slightly enhancing effect on aggregation. When testing two antibodies to CD21, the recently defined ligand for CD23, one of these (BU32) was found to be inhibitory whereas the other (THB5) had no effect. By combining antibodies to LFA-1 and CD23, aggregation was often completely inhibited. These data suggest that LFA-1/ICAM-1 and CD23/CD21 are the major molecules involved in homotypic aggregation of human B cells.