Respiratory inhibition in Chlorella produced by "purified" polyethylene glycol 1540.

Polyethylene glycol 1540, added to culture solution in amounts sufficient to reduce the water potential to -10 atmospheres, inhibited respiration in Chlorella much more than mannitol solutions at -10 atmospheres. This occurred despite the purification of the polyethylene glycol by passage through exchange columns. The toxic properties, which developed some time after purification, increased with time of storage of solutions of polyethylene glycol 1540 at room temperature.

Nitrogen uptake and growth of wheat during O2 deficiency in root media containing NO3 - only, or NO3 - plus NH4.

The effects of hypoxia at 0.003 mol O2 m-3 on growth and nitrogen uptake of wheat seedlings (Triticum aestivum L. ev. Gamenya) was compared between plants growing in nutrient solutions containing either NO3 - only, or NO3 - plus NH4 + . Hypoxia reduced the uptake of N by the plants, however both at 0.28-0.31 mol O2 m-3 (aerated solutions) and 0.003 mol O2 m-3 , rates of N uptake from solutions containing NO3 - plus NH4 + were 34% higher than from solutions containing NO3 - only. In aerated solutions, growth was faster when NO3 - plus NH4 + was supplied. By contrast, at 0.003 mol O2 m-3 both N treatments had the same low growth rate (expressed on a dry weight basis) despite considerably higher internal N concentrations in the plants supplied with NO3 - plus NH4 + . It is concluded that N nutrition did not limit growth at 0.003 mol O2 m-3 in either N treatment. Other possible causes of the growth reduction and differences in uptake characteristics between NO3 - and NH4 + are discussed.

Treatment of cutaneous squamous cell carcinomas by intralesional interferon alfa-2b therapy.

BACKGROUND AND DESIGN: Intralesional recombinant interferon alfa-2b has been shown to be effective in the treatment of actinic keratoses and basal cell carcinomas. This open-label study was designed to evaluate the effectiveness and cosmetic result of this therapy on actinically induced, primary cutaneous squamous cell carcinomas. Thirty-six squamous cell carcinomas (28 invasive lesions and 8 in situ lesions) ranging in size from 0.5 to 2.0 cm in the longest dimension were treated with interferon alfa-2b 1.5 million units injected intralesionally three times per week for 3 weeks. Eighteen weeks following therapy, the treatment sites were excised and examined for histologic evidence of remaining tumor. RESULTS: Thirty-three (97.1%) of 34 evaluable lesions revealed an absence of squamous cell carcinoma histologically after therapy, although three biopsy specimens (8.8%) obtained after treatment showed actinic keratoses, for an overall complete response rate of 88.2%. The lesion not eliminated after treatment was an invasive squamous cell carcinoma. The investigators and patients independently judged 93.9% of cases to have a very good or excellent cosmetic result. Adverse reactions were limited to those influenzalike symptoms well recognized to occur with interferon therapy and these were well tolerated. Only one patient discontinued therapy due to side effects. CONCLUSIONS: This trial demonstrates that intralesional interferon is effective in the treatment of small sun-induced squamous cell carcinomas with well-tolerated side effects and a highly acceptable cosmetic result.

Telomerase activity in Kaposi's sarcoma, squamous cell carcinoma, and basal cell carcinoma.

Patients with acquired immune deficiency syndrome (AIDS) often develop Kaposi's sarcoma (KS), an unusual skin tumor. The malignant nature of KS has long been disputed. Telomerase activity that maintains telomere length and ensures chromosomal stability, a frequently appearing marker in human malignancies, has been proposed to play a critical role in supporting continued cell growth, hence formation of tumors. We examined telomerase activity in tissue extracts from 22 KS, 10 squamous cell carcinoma (SCC), and 22 basal cell carcinoma (BCC) using the telomeric repeat amplification protocol (TRAP). All of the tumor tissues were previously cryopreserved at -80 degrees C. In this study, all tumor samples tested were positive for telomerase activity. Consistent with the presence of the enzyme activity, the skin tumors had relatively long telomeres. Inhibitors in the tissue extracts of some samples needed to be diluted or extracted by phenol before the enzyme activity was detected in the TRAP assay. All KS as well as two other skin carcinoma samples revealed positive telomerase activity. Our finding supports telomerase's role in tumor cell immortality and suggests the true neoplastic nature of KS.

Recognition and management of high-risk cutaneous tumors.

The majority of cutaneous malignancies can be treated by the military dermatologist in a clinical setting. Recognition of tumors at high risk for recurrence or metastasis is important for any dermatologist but especially list care. Providing optimal care includes knowledge about which patients should be medavacced to larger medical centers for advanced surgical and medical treatments.

New trends in skin tumor surgery.

Over 8 years, 1700 patients were referred from the Mohs' Surgery and Cutaneous Laser Unit after Mohs micrographic skin tumor excision to the Division of Plastic and Reconstructive Surgery. Preoperative coordination between the two divisions was emphasised in wound preparation and timing of reconstruction for maximized patient convenience and outcome. Most repairs of facial and extremity defects were carried out under local anesthesia. Techniques of repair were selected based upon algorithmic priorities emphasizing simple techniques over complex ones. Direct closure, skin grafts and flaps were used. Preference for aesthetic subunit reconstruction of the face and the use of particular flap techniques including the O-to-S, O-to-T, V-to-Y island advancement, islandized nasolabial flap for alar reconstruction and the forehead flap for nasal dorsum and tip repair are illustrated.

Salt responses of enzymes from species differing in salt tolerance.

Enzymes which are affected by the addition of inorganic salts during in vitro assay were extracted from salt-sensitive Phaseolus vulgaris, salt-tolerant Atriplex spongiosa, and Salicornia australis and tested for sensitivity to NaCl. In each case malate dehydrogenase, aspartate transaminase, glucose 6-phosphate dehydrogenase, and isocitrate dehydrogenase showed NaCl responses similar to those found for commercially available crystalline enzymes from other organisms. Enzymes extracted from plants grown in saline cultures showed no important changes in specific activity or salt sensitivity. Interaction of pH optima and NaCl concentrations suggests that enzymes may differ in the way they respond to salt treatment.

Effects of slowly permeating osmotica on metabolism of vacuolated and nonvacuolated tissues.

Vacuolated and nonvacuolated root tissues of Zea mays were exposed to low water potentials by addition of mannitol or glycerol. Temporary increases were observed for O(2) uptake, but CO(2) evolution remained steady. This increase in O(2) uptake ceased after 15 minutes. Further treatment induced decreases in respiration, with similar reductions in O(2) uptake and CO(2) evolution.Removal of osmotica from nonvacuolated tissues restored high rates of respiration, uptake of glucose, and synthesis of methanol-insoluble compounds. In contrast, rates of all these processes decreased to very low values when vacuolated tissues were returned to high water potentials. Deplasmolysis also induced rapid leakage of metabolic intermediates from vacuolated tissues, but leakage from nonvacuolated tissues was only slightly increased. It is suggested that these contrasting responses of vacuolated and nonvacuolated tissues are related to differences in structural changes, during either plasmolysis or deplasmolysis.

Effects of rapidly and slowly permeating osmotica on metabolism.

Zea mays was exposed to solutions of low water potentials by addition of ethylene glycol or mannitol. Intact seedlings were treated for 1 hr at potentials between -10 and -20 atmospheres and then returned to high water potentials. Subsequent root extension was slow after mannitol treatment, but rapid when ethylene glycol had been used as the osmoticum. Cellular activity of excised roots was also affected much less by ethylene glycol than by mannitol. Processes studied included respiration, glucose uptake, and synthesis of methanol-insoluble compounds. These differences in response to various osmotica applied both during and after treatment at low water potentials.Ethylene glycol penetrated the tissues much more rapidly than mannitol. Rapid penetration of the osmoticum would minimize turgor loss and plasmolysis. Thus, the data suggest that adverse effects were induced by water loss or structural changes, or both, during plasmolysis, rather than by low water potentials, demonstrating the crucial importance of osmotic adjustment.

Phosphorus transport to the xylem and its regulation by water flow.

The effects of water flow on phosphorus uptake by roots and on its subsequent translocation to shoots were separated by giving short-term pulses of (32)P-labelled nutrient to intact tomato plants. At the end of a 5 min pulse, all the (32)P taken up by the plants was confined to the roots. Only about half of this (32)P was later translocated to shoots; there was very little translocation after 4 hours.Experiments after long-term labelling showed that only a small part of the total P in the root is readily translocated to shoots. This P appears to be in part of the symplast and contributes about 75% of the P transported to the xylem sap. The rest is presumably derived by leakage from vacuoles.A slow rate of water flow reduced both uptake into the symplast and the translocation to the shoots of P which had already been absorbed by the roots. This was conclusively demonstrated by giving a (32)P pulse before reducing the rate of water flow; (32)P not translocated to shoots was partly retained by the roots and partly lost to the external solution. Water flow also accelerates transport to the xylem of previously-absorbed P in excised roots.It is concluded that the major effect of water flow on phosphorus transport to shoots occurs after phosphorus uptake by the roots, probably during radial transport to the xylem.

Phosphorus retranslocation in Hordeum vulgare during early tillering.

In Hordeum vulgare, phosphorus retranslocation was studied after it had been supplied to the roots for three days (experiment 1), and after foliar application (experiments 3-8). Phosphorus uptake by leaves of different ages was also measured 16 and 60 minutes after (32)P addition to the medium (experiment 2).In experiment 1, treatments at 0.6 and 31 p.p.m. of phosphorus were applied when the first leaf had completed its rapid growth. The plants were then grown for three days in media labelled with (32)P, and for a subsequent 10 days in non-labelled solutions. Retranslocation was measured by changes in total phosphorus and in (32)P.Both root feeding, and foliar application of (32)P, demonstrated three phases during leaf development: import (recently initiated leaf), export (mature leaf) and an intermediate phase with both export and import (leaf half developed).There was large transport of foliar applied (32)P, from mature leaves to roots, and some of this (32)P was re-exported to the shoots, including the mature leaves. Root feeding of (32)P over short periods strongly suggested that phosphorus uptake by the shoots occurred via the xylem, even at low phosphorus.In experiment 1, there were distinct treatment differences in relative growth rates, growth of young organs and roots, and in phosphorus concentrations of all but the very young leaves. Mature leaves showed a large net phosphorus export at low phosphorus, but a large net import at high phosphorus. This was not due to treatment differences in export, because total export from the mature leaves was even somewhat smaller at low than at high phosphorus. The treatment differences, with net export at low but net import at high phosphorus, were thus due to the higher import in the mature leaves at high phosphorus. Total export remained at a high level throughout the experiment at high phosphorus, while it declined with time at low phosphorus.For phosphorus absorbed during early growth, both the export from the mature leaves, and the intake by the developing leaves, was independent of phosphorus treatment; i.e. for each individual organ the quantities of phosphorus involved were the same in the two phosphorus treatments. Thus, the higher phosphorus contents of developing organs at high phosphorus were obtained from phosphorus supplied to the roots during later growth, and not from phosphorus supplied during early growth of the whole plant.The data are consistent with the notion that phosphorus export is controlled in the source. It is suggested that at high phosphorus this control is due to a saturation of the sites transporting phosphorus into the phloem. At low phosphorus, on the other hand, release from individual leaf cells might have been the dominating factor.

Metabolic evidence for stelar anoxia in maize roots exposed to low o(2) concentrations.

This investigation presents metabolic evidence to show that in 4- to 5-day-old roots of maize (Zea mays hybrid GH 5010) exposed to low external O(2) concentrations, the stele receives inadequate O(2) for oxidative phosphorylation, while the cortex continues to respire even when the external solution is at zero O(2) and the roots rely solely on aerenchyma for O(2) transport. Oxygen uptake rates (micromoles per cubic centimeter per hour) declined at higher external O(2) concentrations in excised segments from whole roots than from the isolated cortex; critical O(2) pressures for respiration were greater than 0.26 moles per cubic meter O(2) (aerated solution) for the whole root and only 0.075 moles per cubic meter O(2) for the cortex. For plants with their shoots excised and the cut stem in air, ethanol concentrations (moles per cubic meter) in roots exposed to 0.06 moles per cubic meter O(2) were 3.3 times higher in the stele than in the cortex, whereas this ethanol gradient across the root was not evident in roots exposed to 0 moles per cubic meter O(2). Alanine concentrations (moles per cubic meter) in the stele of roots exposed to 0.13 and 0.09 moles per cubic meter O(2) increased by 26 and 44%, respectively, above the levels found for aerated roots, whereas alanine in the cortex was unchanged; the increase in stelar alanine concentration was not accompanied by changes in the concentration of free amino acids other than alanine. For plants with their shoots intact, alcohol dehydrogenase and pyruvate decarboxylase activities (micromoles per gram protein per minute) in roots exposed to 0.13 moles per cubic meter O(2) increased in the stele by 40 to 50% over the activity in aerated roots, whereas there was no appreciable increase in alcohol dehydrogenase and pyruvate decarboxylase activity in the cortex of these roots. More convincingly, for roots receiving O(2) solely from the shoots via the aerenchyma, pyruvate decarboxylase in the cortex was in an "inactive" state, whereas pyruvate decarboxylase in the stele was in an "active" state. These results suggest that for roots in O(2)-free solutions, the aerenchyma provides adequate O(2) for respiration in the cortex but not in the stele, and this was supported by a change in pyruvate decarboxylase in the cortex to an active state when the O(2) supply to the roots via the aerenchyma was blocked.

Mohs Micrographic Surgery for skin cancer.

Mohs Micrographic Surgery is a technique offering superior treatment for skin cancer with cure rates of 99% for primary and 94.4% for recurrent BCC, greater than 94% for SCC. As developed by Dr Frederic Mohs, the technique originally involved application of a chemical fixative. Mohs' fresh tissue technique is now usual, with immediate horizontal frozen sectioning of the entire margins of excised tissue, mapping and microscopic identification of remaining tumour, then repeat excisions, mapping and examination until a tumour-free plane is demonstrated throughout. This provides maximal conservation of uninvolved tissue structures, and allows more confident repair of a cancer-free surgical defect. Mohs Micrographic Surgery is becoming more widely available in Australasia; concurrently, indications for the technique are widening, as are the research interests, training opportunities, and professional organization of Mohs Practitioners. Very high, and increasing, incidence and prevalence of skin cancer in Australasia, and factors tending to contribute to this, suggest that Mohs Micrographic Surgery has an expanding role to play in Australasia.

Effects of Water and Turgor Potential on Malate Efflux from Leaf Slices of Kalanchoë daigremontiana.

Malate efflux from leaf cells of the Crassulacean acid metabolism plant Kalanchoë daigremontiana Hamet et Perrier was studied using leaf slices submerged in experimental solutions. Leaves were harvested at the end of the dark phase and therefore contained high malate levels. Water potentials of solutions were varied between 0 and -5 bar using mannitol (a slowly permeating solute) and ethylene glycol (a rapidly permeating solute), respectively. Mannitol solutions of water potentials down to -5 bar considerably reduced malate efflux. The slowly permeating solute mannitol reduces both water potential and turgor potential of the cells. The water potential of a mannitol solution of -5 bar is just above plasmolyzing concentration. Malate efflux in ethylene glycol at -5 bar was only slightly smaller than at 0 bar, and much higher than in mannitol at -5 bar. Tissues in rapidly permeating ethylene glycol would have turgor potentials similar to tissues in 0.1 mm CaSO(4). The results demonstrate that malate efflux depends on turgor potential rather than on water potential of the cells.

Effects of low water potentials on some aspects of carbohydrate metabolism in Chlorella pyrenoidosa.

Chlorella pyrenoidosa was subjected to low water potentials and the resulting changes in carbohydrate metabolism were measured.Water deficit reduced the incorporation of (14)C-glucose into methanol insoluble compounds, principally starch and increased that into sucrose. Even moderate water deficit, for example potentials of -2.5 and -5 atm, greatly reduced the incorporation of (14)C-glucose into uridine diphosphate glucose, while (14)C levels of the hexose monophosphates changed little, indicating a direct stimulus of sucrose synthesis. This increased sucrose synthesis was one of the earliest effect of water deficit, because potentials of -2.5 and -5 atm did not reduce respiration and glucose uptake.At lower water potentials (-10 atm or less) there was reduced (14)C incorporation into all sugar phosphates. This resulted from a combination of reduced (14)C-glucose uptake and increased sucrose synthesis.Water potentials as low as -20 atm had little effect on acetate uptake, or on the (14)C levels in the intermediates of the TCA cycle. This confirmed that low water potentials do not directly inhibit respiratory pathways in Chlorella.The results are discussed in relation to the effect of water deficit on levels of various metabolites in vascular plants, which have been reported by other workers.