Genetic determination of antibody specificity

The best system for the study of cell differentiation is a cell which in its differentiated state differs only by one product. This is the case in the immune system. The undifferentiated, but omnipotent stem cell differentiates into a committed B cell which produces only one type of specific antibody out of a million different, genetically fixed possibilities. Gene translocation and fusion is the basis of this differentiation process.     

Artificial instillation of amniotic fluid as a new technique for the diagnostic evaluation of cases of oligohydramnios

In cases of severe oligohydramnios, sonographic diagnosis is hampered by poor visibility and by increased fetal flexion. Therefore, 74 artificial instillations of amniotic fluid were performed in 50 pregnancies by sonographic guidance. Fetal diseases included Potter's syndrome, obstructive uropathy, cystic kidneys (20 cases); Meckel's syndrome, C. de Lange syndrome, cytomegaly fetopathy (1 case each); VATER association (2 cases); triploidy (5 cases); severe intrauterine growth retardation (8 cases); and premature rupture of membranes (12 cases). By improved sonographic visibility and the observation of fetal behaviour (drinking, filling of stomach and bladder, voiding of bladder after artificial instillation of amniotic fluid), the fetal anatomy could be studied more accurately, malformations could be identified or excluded, and bladder function could be examined. Thus, differentiation between fetuses without functioning kidneys and those with severe intrauterine growth retardation becomes possible. Further, re-aspiration on the day following instillation permitted determination of the karyotype. Finally, the artificial instillation of amniotic fluid is a hazardous intervention (rupture of membranes, labour) and should be reserved only for a small number of selected cases with diagnostically unclear oligohydramnios. For these cases, it seems to be the method of choice permitting a variety of diagnostic information to be obtained.     

Prenatal diagnosis of alpha-1-antitrypsin deficiency by PCR of linked polymorphisms: A study of 17 cases

We describe our experiences of prenatal diagnosis of alpha-1-antitrypsin deficiency using closely linked polymorphisms detected by Southern blotting and the polymerase chain reaction. Prenatal diagnosis was carried out for 17 pregnancies from 15 couples.     

Symbiosis and Pathogenesis: Evolution of the Microbe-Host Interaction

Symbiotic and pathogenic bacteria have in common that they live in or on host organisms or host cells. To make a successful living in eukaryotic hosts, bacteria must possess the traits to recognize a given host and establish adherence. When the bacterial location is internal or intracellular, they must further have the ability to invade, to establish a niche, and finally to multiply within a host. The underlying mechanisms which allow this form of existence show similarities between symbiotic and pathogenic bacteria. The final outcome, however, may result in a wide spectrum of consequences for the host ranging from the acquisition of novel metabolic pathways to damage or death. Despite the vastly different forms of interactions, symbiotic and pathogenic bacteria have in common that they are adapted to a particular environmental niche represented by the host organism or compartment thereof. This contribution reviews the evolutionary forces which have shaped the microbial-host interactions. Particular emphasis is placed on the genetic and molecular mechanisms that drive bacterial evolution in response to the selective pressures of the host environment.