Role of phosphorylation in regulation of the assembly of endocytic coat complexes

Clathrin-mediated endocytosis involves cycles of assembly and disassembly of clathrin coat components and their accessory proteins. Dephosphorylation of rat brain extract was shown to promote the assembly of dynamin 1, synaptojanin 1, and amphiphysin into complexes that also included clathrin and AP-2. Phosphorylation of dynamin 1 and synaptojanin 1 inhibited their binding to amphiphysin, whereas phosphorylation of amphiphysin inhibited its binding to AP-2 and clathrin. Thus, phosphorylation regulates the association and dissociation cycle of the clathrin-based endocytic machinery, and calcium-dependent dephosphorylation of endocytic proteins could prepare nerve terminals for a burst of endocytosis.     

Hospital costs--the medical student component

A study of indirect costs which could be attributed to undergraduate teaching in a large affiliated teaching hospital has shown that they are very small. Thus direct university costs in 1975 were $1,800,000 (7-6% of all expenditure at the hospital); indirect costs were $41,000 (approximately 0-2% of the hospital expenditure). It is concluded that the 45% difference in bed costs per day between teaching and non-teaching hospitals from a previous investigation is therefore not the result of the clinical school indirect demands on hospital expenditure.     

Verrucous carcinoma of skin: epithelioma cuniculatum plantare

Eight patients had plantar growths that were usually irregularly shaped, sharply outlined, verrucous, and several centimeters in greatest dimension. Clinical diagnoses included viral wart, deep mycosis, pyogenic granuloma, amelanotic melanoma, basal cell carcinoma, and eccrine poroma. The median age of the patients, and duration of the growth, were 52 and 16 years, respectively. Therapeutic modalities other than total excision were ineffective. The tumor, derived from surface epidermis, was composed of masses of pale-staining benign-appearing prickle cells, deeply invaginated by thick, compact, partially parakeratotic horn. Several lesions have recurred; amputation was required in one patient. This distinctive entity, apparently not described in the American literature, has been reported from Europe under such titles as epithelioma cuniculatum and papillomatosis cutis carcinoides. We believe that it is best interpreted as a form of verrucous carcinoma, the first cutaneous tumor--as opposed to lesions of mucous membranes and mucocutaneous junctions--to be so classified.     

Characterization of human faecal flora by means of an improved fluoro-morphometrical method

The use of polyclonal antibodies in differentiating between samples of faecal microflora derived from ten healthy volunteers was assessed. The distribution of FITC-labelled antibodies (of the IgA, IgG and IgM isotype) over 144 morphologically distinct subsets of faecal bacteria ('morphotypes') was quantified by means of digital morphometry and quantitative immunofluorescence. Furthermore, a new dataprocessing algorithm was developed which makes objective quantitation of the antibody distributions over the faecal morphotypes possible. The results of this study imply that the antibody binding capacity of faecal morphotypes is a unique characteristic of faecal microflora.     

In situ preservation of kidneys from non-heart-beating donors--a proposal for a standardized protocol

The growing success in renal transplantation has resulted in an increase in the need for donor organs. Procurement of kidneys from heart-beating (HB) donors is unlikely ever to meet this demand. Non-heart-beating (NHB) donors offer a yet untapped source of renal grafts. Cadaver kidneys from patients who have sustained cardiac standstill are often considered unsuitable for transplantation due to prolonged warm ischemia time. Using an emergency in situ perfusion technique it is possible to limit warm ischemic damage and to salvage these kidneys for transplantation. The procedure requires prompt action and cooperation of emergency service personnel. This report presents a protocol for the emergency in situ preservation procedure that can be practiced in most hospitals. At the University Hospital of Maastricht, The Netherlands, implementation of this procedure resulted in 20% more kidneys available for transplantation. Although NHB donor kidneys showed a higher rate of delayed function compared with a matched HB donor kidney population, there was no significant difference in long-term graft survival between the two groups.     

Greater emotional distress is associated with accelerated CD4+ cell decline in HIV infection

The hepatic transport of the immunosuppressive Cyclosporin A (CyA) was studied using liposomal phospholipid membranes, freshly isolated rat hepatocytes and bile canalicular plasma membrane vesicles from rat liver. The Na(+)-dependent, saturable uptake of the bile acid 3H-taurocholate into isolated rat liver cells was apparently competitively inhibited by CyA. However, the uptake of CyA into the cells was neither saturable, nor temperature-dependent nor Na(+)-dependent, nor could it be inhibited by bile salts or CyA-derivatives, indicating passive diffusion. In steady state depolarization fluorescence studies, CyA caused a concentration-dependent decrease of anisotropy, indicating a membrane fluidizing effect. Ion flux experiments demonstrated that CyA dramatically increases the permeability of Na+ and Ca2+ across phospholipid membranes in a dose- and time-dependent manner, suggesting a iontophoretic activity that might have a direct impact on cellular ion homeostasis and regulation of bile acid uptake. Photoaffinity labeling with a [3H]-labeled photolabile CyA-derivative resulted in the predominant incorporation of radioactivity into a membrane polypeptide with an apparent molecular weight of 160,000 and a minor labeling of polypeptides with molecular weights of 85,000-90,000. In contrast, use of a photolabile bile acid resulted in the labeling of a membrane polypeptide with an apparent molecular weight of 110,000, representing the bile canalicular bile acid carrier. The photoaffinity labeling as well as CyA transport by canalicular membrane vesicles were inhibited by CyA and the p-glycoprotein substrates daunomycin and PSC-833, but not by taurocholate, indicating that CyA is excreted by p-glycoprotein. CyA uptake by bile canalicular membrane vesicles was ATP-dependent and could not be inhibited by taurocholate. CyA caused a decrease in the maximum amount of bile salt accumulated by the vesicles with time. However, initial rates of [3H]-taurocholate uptake within the first 2.5 min remained unchanged at increasing CyA concentrations. In summary, the data indicate that CyA does not directly interact with the hepatic bile acid transport systems. Its cholestatic action may rather be the result of alterations in membrane fluidity, intracellular effects and an interaction with p-glycoprotein.     

Subdivisions of the olfactory system in the sterlet Acipenser ruthenus

Subdivisions of the olfactory system of the sterlet Acipenser ruthenus were investigated by means of horseradish peroxidase (HRP) injections into the nose, and by soybean agglutinin binding studies. With both methods primary olfactory fibers were labeled which projected to the ventral part of the glomerular layer of the olfactory bulb. The dorsal part of the olfactory bulb did not bind soybean agglutinin, however, even though HRP tracing showed primary olfactory fibers in that area. This confirms earlier morphological studies which claim the existence of distinct subdivisions of the olfactory system in the sturgeon. The lack of soybean agglutinin binding in the dorsal part of the olfactory bulb suggests, however, that this part is not homologous with the accessory olfactory system of tetrapods.