Orderly arrangement of ribosomes in the embryogenic callus tissue of Corylus avellana L.

Cultured callus tissue of hazel (Corylus avellana L.), which has the potency of somatic embryogenesis, was used for the study of cell ultrastructure in the course of callus growth and embryoid formation. The meristematic cells of this tissue exhibit a specific organization of rough endoplasmic reticulum (RER), stacked into extensive parallel sheets. The membranes of the aggregated RER are associated with orderly arrays of bound ribosomes. The high regularity of the alignment of the attached ribosomes seems to be influenced by the distance between the two neighbouring membranes in the RER aggregate. The RER aggregates with orderly attached ribosomes are more frequently found in callus cells and in early embryogenesis than in the advanced stages of embryo development.

Prostaglandin E1 reduces the frequency of rejection after heart transplantation.

This retrospective study was carried out to evaluate the effect of prostaglandin E1 on the frequency of rejection in 36 heart transplant recipients who survived orthotopic heart transplantation for 60 days or longer. The therapy for both groups was the same except group 1 (n = 12) was given PGE1 for 6 to 14 days. Indication for the PGE1 was right ventricular mismatch or failure. The prostaglandin administration started during the transplantation procedure. The dosage was 28 to 64 ng/kg/min and was tapered down from 14.7 to 32 ng later. No major side effects related to PGE1 have been observed. During the first 60 days after heart transplantation, in the group treated with prostaglandin, rejection grade 2 or higher was evident in 0.91 biopsies/patient versus 2.2 in nontreated patients, (p less than 0.05). A prolonged interval free from rejection (p less than 0.05) was observed in the patients treated with prostaglandin.

Critical care medicine in cyperspace: Internet resources and techniques for the intensivist.

The internet, is an informational tool of impressive proportions and capabilities. New software developments puts the use of this informational technology into the hands of all physicians. The use of Internet informational resources allows the intensivist to stay abreast of new developments in critical care medicine, communicate in a matter of seconds with colleagues half a world away, acquire medically related software, access remote database structures, obtain continuing medical education, and in the near future to "see' patients and obtain physiological data in real time. This tutorial will introduce the Internet and it's current tool suite.

Somatic embryogenesis and bud formation from immature embryos of buckwheat (Fagopyrum esculentum Moench.).

Immature embryos of Fagopyrum esculentum cv. Pennquad were isolated from field-grown plants and cultured on media containing a high benzylaminopurine to indole-3-acetic acid ratio. Part of the embryos were grown in the presence of 2,4-dichlorophenoxyacetic acid and kinetin for the first 5 days, and then transferred to benzylaminopurine + indole-3-acetic acid medium. From callus tissues developed on hypocotyls and cotyledons, 3 types of tissue were selected in later subcultures: (a) callus tissue strains that produced buds, (b) embryogenic tissue, and (c) unorganized callus tissue, lacking any organogenic capacity. Pretreatment with 2,4-dichlorophenoxyacetic acid increased the number of explants which gave rise to bud forming and embryogenic tissue, but was not essential for morphogenesis. Somatic embryogenesis was confirmed by histological observation. Plantlets could be easily obtained by inducing adventitious roots on shoots, but spontaneous root development in somatic embryos was infrequent.

Membranous aggregates in hyphal tips of Aspergillus flavus.

An excessive endomembrane system found in the form of aggregated cisternae in the young growing hyphal tips of Aspergillus flavus is described. The disposition of the aggregate adjacent to the apical dome, and its close association with spical vesicles suggests an active involvement of these aggregated cisternae in the cell wall synthesis. By the use of cytochemical methods it was demonstrated that the apical vesicles originate from some of the dilated elements of the aggregate.