C.F. van der Merwe

A phase II study of neocarzinostatin (NSC 157365) in malignant hepatoma

SummaryThirty evaluable patients with histologically confirmed primary liver cancer (PLC) were treated with neocarzinostatin (NCS). All patients had measurable disease and an Eastern Cooperative Oncology Group (ECOG) performance status of 1, 2, or 3. NCS 2250 units/m2 was given daily for 5 days, repeated at 28-day intervals. Hemopoietic suppression was the major side effect. In 23 of 30 patients (13 with leukopenia and 19 with thrombocytopenia), this toxic effect was documented. Other toxic effects included nausea, vomiting, allergictype reaction, and elevation of NPN. Partial response, with a median duration of 12.7 weeks (range 4–37 weeks) was observed in seven patients. In nine patients the response was classified as no change, and in 14 patients there was progressive disease. NCS has some therapeutic activity in patients with PLC.

Lenticel discolouration in mango (Mangifera indica L.) fruit – a cytological study of mesophyll cells from affected tissue

Summary Mango fruit is characterised by the presence of lenticels, with some cultivars prone to a condition known as ‘lenticel damage’. The condition manifests itself as a localised red-to-dark discolouration around the lenticels. The presence of these unacceptable spots on mature green fruit has economic implications. The cytological nature of lenticel discolouration was investigated as part of a study of affected mango fruit. Lenticels were dissected from physiologically mature fruit in predetermined groups of varying discolouration. Transmission electron microscopy and light microscopy of mesophyll cells from affected tissue indicated conservation of cellular structures and endomembranes in all variants of discolouration. It was therefore shown that the accumulation of cell wall-bound phenolics does not result from structural damage such as vacuolar collapse or membrane disintegration. Results further suggest the apoplastic transport of the signal for phenolics deposition. Accumulation of phenolic compounds in a distinct zone of affected tissue around the lenticel creates a barrier between the atmosphere and the rest of the mesophyll. Although lenticel discolouration is an inherent self-defence mechanism supported by continued metabolic activity, it is a superficial, cosmetic defect.

Histological assessment of SJL/J mice treated with the antioxidants coenzyme Q10 and resveratrol.

The muscular dystrophies (MDs) are genetic disorders of muscle degeneration due to mutations in genes that encode a wide variety of proteins. Dysferlinopathy are characterized by the absence of dysferlin in skeletal muscle and an autosomal recessive mode of inheritance. Both histological and ultrastructural pathology have been well established in dysferlinopathy patients and dysferlin-deficient animal models. To our knowledge the effect of antioxidant supplementation on this level has not been described previously. This article therefore focuses on the histopathology to reveal the effect of antioxidant supplementation. The study aimed to determine, at cellular level, the histopathological changes in the SJL/J mouse model following a 90 day trial with antioxidant supplementation. Markedly reduced inflammatory insult in the more affected quadriceps muscles of animals treated with high doses of CoQ10 and a combination of resveratrol/CoQ10 were observed. The outcome provides evidence that high doses of antioxidant supplementation resulted in decreased dystrophic markers and enhanced tissue integrity at cellular level.

Phytotoxic effects of fumonisin B1 on cowpea seed

The cultivation of cowpea (Vigna unguiculata) plays a vital role in the livelihood of many subsistence farmers and rural communities in tropical and subtropical countries. The seeds are prone to fungal infestation and mycotoxin contamination during sub-optimal storage conditions. Fumonisin B1 (FB1), produced byFusarium proliferatum, has been detected in cowpea seeds. Surface-disinfected seeds were imbibed in sterile distilled water amended with FB1 at various concentrations. Percentage germination was determined according to the International Seed Testing Association rules. All the toxin concentrations significantly decreased seed germination and the two highest concentrations — 50 and 100µg ml−1 FB1 — inhibited root and shoot elongation. FB1-treated embryonic tissues evinced compaction of the protoplasm and separation of the plasmalemma from the cell wall. Lipid bodies accumulated, which seemed to be lining the cell wall. This is the first study to demonstrate the phytotoxic effects of FB1 on cowpea seeds.

Immunogold Localization and Quantification of Cellular and Subcellular Abscisic Acid, Prior to and During Drought Stress

An immunogold labeling procedure and experimental data are presented, which demonstrate that antibodies produced against a bovine serum albumin-abscisic acid conjugate can be used both to characterize the cellular and subcellular localization of abscisic acid (ABA), and to permit quantitative comparisons of this hormone in the subcellular compartments prior to and at times of drought stress. At the control leaf water potential (approximately -0.45 MPa), a quantitatively similar positive labeling pattern was observed in the chloroplasts and apoplast. A twofold drought stress-induced increase in the apoplastic ABA concentration was observed in the drought stressed leaf tissue (i.e., at a leaf water potential of approximately -1.55 MPa), while the ABA concentration in the chloroplasts did not differ from that of the controls. Three histochemical controls and the physiological observations validated the specificity of the procedure. Based on the labeling patterns we observed and literature cited, the validity of the hypothesis that drought stress induces a release of chloroplastic ABA is questioned. We interpreted our results as providing indirect evidence for a drought stress-induced root source origin for the increased apoplastic ABA concentrations.

Contributions to the floral morphology and embryology of Pavetta gardeniifolia A. Rich. Part 2. The ovule and megasporogenesis

In Pavetta gardeniifolia the ovule is hemitropous, unitegmic with a rudimentary nucellus and a monosporic, Polygonum -type embryo sac. The base of the ovule is encircled by an aril-like tissue with papillate cells secreting a mucilage in which the seed-borne leaf-nodulating bacteria are harboured. The ultrastructure of these cells as well as their relation to a true aril is discussed. Fertilization is porogamous. Endosperm development is nuclear and in the mature seed it is proteinaceous.

Expression of the H-subunit and L-subunit of ferritin in bone marrow macrophages and cells of the erythron during cellular immune activation

BACKGROUND The expression of the two types of ferritin subunits, the H-subunit and L-subunit, has been shown to be differentially regulated by cytokines. The primary aim of the present study was to quantitatively measure the expression of the H-subunit and L-subunit of ferritin in bone marrow macrophages and cells of the erythron in patients with chronic T-helper cell type-1 immune stimulation. METHODS The expression of the H-subunit and L-subunit of ferritin in bone marrow macrophages and cells of the erythron was quantitatively evaluated by post-embedding immunolocalisation with immunogold transmission electron microscopy. RESULTS The present study showed up-regulation of the H-subunit of ferritin in the bone marrow macrophage in patients with pronounced cellular immune activation (94.7±37.3 counts/μm(2); n=31 vs 72.4±34.0 counts/μm(2); n=13, p-value=0.037). CONCLUSION This supports a possible role for H-subunit rich ferritins in the hypoferraemia of chronic disease.

The transmitting tract in Gloriosa superba: Structure, pistil exudate and pollen tube growth

The structure of the pistil exudate, transmitting tissue and pollen tube growth of Gloriosa superba L. were studied. Flowers are protogynous, as the stigmas become receptive one day prior to anther dehiscence, and remain receptive for at least four days. Neutral red and auramine O proved to be useful for the indication of stigma receptivity. The stigma is wet while the papillae and canal cells form slight interior cell wall ingrowths reminiscent of transfer cells. Pistil exudate is mostly lipidic, confirmed by the prevalence of endoplasmic reticulum in the cytoplasm. The canal exudate includes substances derived from degenerating canal cell walls and lipid-like vesicles breaking down into fine fibrillar matter possibly associated with the pollen tube cell wall. Pollen tubes grow in close association with the stylar secretion, reaching most ovules, even though pollen tube numbers decrease on their way down the stylar canal. Callose deposition in the nucellus of some self-pollinated ovules could be indicative of a partly pre-zygotic gametophytic self-incompatibility system.

The influence of processing protocol on the ultrastructure of bean leaf cells

Bean leaf cells exhibit ultrastructural damage when glutaraldehyde fixatives or buffer washes are applied for prolonged periods. The maximum times in these processing steps are influenced by the choice of buffer. Prolonged periods in low concentrations of acetone also cause damage. This damage is progressively less obvious in higher concentrations. Extended holding times In anhydrous acetone are possible, especially if phosphate or cacodylate buffers are employed during fixation.

Contributions to the floral morphology and embryology of Pavetta gardeniifolia A. Rich. Part 3. Microsporogenesis and pollen structure

The anther wall development as well as microsporogenesis in Pavetta gardeniifolia is described. The microspore mother cells as well as the individual microspores in the tetrahedral tetrads are enveloped in callose walls. Mature pollen grains are tricolporate with a punctitegullate sexine and are shed in the binucleate stage.