Cryopreservation of chloroplasts and thylakoids for studies of protein import and integration

A method is presented for preservation of isolated intact chloroplasts and isolated thylakoids for use in chloroplast protein import and thylakoid protein integration studies. Chloroplasts of pea (Pisum sativum) were preserved by storage in liquid nitrogen in the presence of a cryoprotective agent. Dimethyl sulfoxide was the most effective of several cryoprotectants examined. Approximately 65 to 70% of chloroplasts stored in liquid nitrogen in the presence of dimethyl sulfoxide remained intact upon thawing and were fully functional for the import of precursor proteins. Imported proteins were correctly localized within these chloroplasts, a process that for two of the proteins tested involved transport into the thylakoids. Lysate obtained from preserved chloroplasts was functional for protein integration assays. Preserved chloroplasts retained import and localization capability for up to 6 months of storage. Thylakoids were preserved by a modification of a method previously described (Farkas DL, Malkin S [1979] Plant Physiol 64: 942-947) for preservation of photosynthetic competence. Preserved thylakoids were nearly as active for protein integration studies as freshly prepared thylakoids. The ability to store chloroplasts and subfractions for extended periods will facilitate investigations of plastid protein biogenesis.

[Experimental studies on the decoction siwu tang]

Using many kinds of modern instruments, we have measured the content of ferulic acid, eight trace elements, seventeen amino acids and water-soluble substances in various single drug decoctions, group-drug decoctions, and mixtures of various single drug decoctions of radix Angelicae sinensis, radix Rehmanniae, radix Paeoniae alba and Rhizoma chuanxiong that make up the decoction siwu tang. Absorption peaks in ultraviolet spectra have also been measured.

Long-term survival in breast cancer related to overexpression of the c-erbB-2 oncoprotein: an immunohistochemical study using monoclonal antibody NCL-CB11

In a previous series we have shown poor short-term (3-5 years) survival for patients with tumours overexpressing the c-erbB-2 oncoprotein. In this study we employed archival paraffin-embedded tissue from patients who underwent mastectomy 10-12 years prior to assessment (n = 187). Immunohistochemical staining was carried out by an indirect immunoperoxidase technique using the novel monoclonal antibody NCL-CB11. Tumours were scored according to intensity of membrane staining. Patient and tumour information was obtained by scrutiny of clinical records. Survival analysis was carried out for both time to relapse and time to death, using the log rank test. Patients with tumours demonstrating intense membrane staining had a poor prognosis compared with the rest, with a steeply sloped survival curve over the first 4 years; the survival difference was still evident at 12 years follow-up (P less than 0.001). The survival advantage for c-erbB-2 negative patients was maintained in lymph node negative patients (P less than 0.001). However, c-erbB-2 status did not influence survival in the node positive group, where all patients had a uniformly poor outlook. These results applied to both time to relapse and time to death. In conclusion, c-erbB-2 status, determined using NCL-CB11, is a powerful prognostic indicator, defining in particular node negative patients with a particularly poor prognosis, and for whom alternative therapeutic strategies may be appropriate.

Administrative priorities: decisions and strategies that attract and retain quality staff

This article represents the second part of a presentation delivered at the 1989 National Association for Home Care annual meeting. This segment addresses structural components necessary to attract and retain quality staff, and issues related to retention that are within administrative control.

[Pathogenesis of Alzheimer's disease]

The 160 and 200 Kd phosphorylated and non-phosphorylated neurofilament monoclonal antibodies were used as the probe to study the cytoskeletal protein distribution inside cerebral neurons of 2 normal adults and 2 patients with Alzheimer's disease (AD). Immunocytochemical technique was applied in this study. Non-phosphorylated neurofilament was located in the perikarua, whereas, the phosphorylated neurofilament was rich in the peripheral of the neuron's cell body and axons in the normal adult brain. In AD, no significant difference was seen when non-phosphorylated neurofilament was compared with normal adult brain; but phosphorylated neurofilament was seen accumulated inside the neuron's cell bodies. We did not find any immunoreactivity of the above cytoskeletal proteins in the senile plaques. These results indicate that the accumulation of high molecular weight phosphorylated neurofilament inside the neuron's cell bodies is the early pathogenetic change of AD.

Development of a high affinity and stereoselective photoaffinity label for the D-1 dopamine receptor: synthesis and resolution of 7-[125I]iodo-8-hydroxy-3-methyl-1-(4'-azidophenyl)-2,3,4,5-tetrahydro- 1H-3-benzazepine

In an earlier paper, we reported the development of (+-)-7-iodo-8-hydroxy-3-methyl-1-(4'-azidophenyl)-2,3,4,5-tetrahydro- 1H-3-benzazepine (I-MAB) and its 125I analogue ([125I]I-MAB) as selective, high affinity photoaffinity labels for the D-1 dopamine receptor. In this report, we now describe the complete synthesis and resolution of I-MAB and the pharmacological characterization of the stereoisomers in canine striatal membranes. R-(+)-I-MAB showed highly specific dopamine D-1 receptor binding (KD = 0.28 nM) and binds selectively and stereoselectively to the D-1 receptor. These results further confirm the previous suggestion that, in the benzazepine series of DA agonists and antagonists, the activity principally resides in the R-(+) enantiomer, the S-(-) enantiomer being considerably less potent or inactive. Moreover, R-(+)-[125I]I-MAB, upon photolysis, identifies the ligand-binding subunits of the neuronal D-1 receptor, with an apparent Mr of 74,000, 62,000, and 51,000 as assessed by autoradiography following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Photoincorporation of R-(+)-[125I]I-MAB into these polypeptides was stereoselectively blocked by D-1 dopaminergic ligands with an appropriate pharmacologic profile for the receptor. R-(+)-[125I]I-MAB should thus prove to be a useful stereoselective photoaffinity label for the further characterization of the D-1 receptors.

A lamin B receptor in the nuclear envelope

Using a solution binding assay, we show that purified 125I-labeled lamin B binds in a saturable and specific fashion to lamin-depleted avian erythrocyte nuclear membranes with a Kd of approximately 0.2 microM. This binding is significantly greater than the binding of 125I-labeled lamin A and is competitively inhibited by unlabeled ligand. We demonstrate that a 58-kDa integral membrane protein (p58) is a lamin B receptor by virtue of its abundance in the nuclear envelope and association with 125I-labeled lamin B in ligand blotting assays. Specific antibodies raised against p58 recognize one protein in isolated nuclei and partially block 125I-labeled lamin B binding to lamin-depleted nuclear membranes. Cell fractionation and indirect immunofluorescence microscopy show that p58 is located in the periphery of the nucleus. This protein may serve as a membrane attachment site for the nuclear lamina by acting as a specific receptor for lamin B.

A gentle method for preparing cyto- and nucleo-skeletons and associated chromatin

We describe a method for permeabilizing and extracting cells that preserves both structure and function whilst allowing the cell derivatives to be handled freely. Cells are encapsulated in microbeads of agarose; the coat of agarose, which is freely permeable to small molecules, forms a protective layer around fragile cell constituents. Cells are then permeabilized by the non-ionic detergent Triton X-100 or antibody and complement in a buffer whose ionic composition mimics that of the cytoplasm. The resulting structures have been characterized morphologically (by immunofluorescence and electron microscopy) and biochemically. Lysis with Triton removes both cell and nuclear membranes, and extracts most of the cytoplasm to leave chromatin surrounded by cytoskeleton; nucleus and cytoplasm then become accessible to triphosphates, enzymes and antibodies. Lysis with complement permeabilizes the cell membrane but leaves the nuclear membrane intact; triphosphates and restriction enzymes, but not antibodies, can then enter both nucleus and cytoplasm. Both types of lysis yield preparations whose chromatin template remains essentially intact, and which is replicated and transcribed at rates close to, or greater than, those found in vivo. Treatment of complement-lysed cells with Triton reduces the very efficient DNA synthesis, implying that the nuclear membrane is involved, directly or indirectly, in replication.

Distribution of ATPase-positive Langerhans cells in normal adult human skin

The distribution of ATPase-positive Langerhans cells (LC) was investigated in 117 specimens of normal adult human skin and mucosa taken from different areas of the body. Although there were significant variations in the numbers of LC in each area examined, skin from the face and neck contained the highest density of cells (976 +/- 30.93/mm2). The densities of LC in trunk skin (740 +/- 28.97/mm2), scalp (693 +/- 69.56/mm2) and arm or leg skin (640 +/- 40.95/mm2) were similar. Buccal mucosa had significantly fewer LC (567 +/- 42.94/mm2) than trunk skin, and sacrococcyx skin and palm and sole skin displayed the smallest number of these cells (267 +/- 56.14/mm2 and, 189 +/- 19.15/mm2 respectively). No ATPase-positive LC were detected in the centre of two corneal specimens.