Salt leaching leads to drier soils in disturbed semiarid woodlands of central Argentina.

Disturbances in semiarid environments have revealed a strong connection between water, salt and vegetation dynamics highlighting how the alteration of water fluxes can drive salt redistribution process and long-term environmental degradation. Here, we explore to what extent the reciprocal effect, that of salt redistribution on water fluxes, may play a role in dictating environmental changes following disturbance in dry woodlands. We assessed salt and water dynamics comparing soil-solution electrical conductivity, chloride concentration, soil water content (SWC) and soil matric and osmotic water potential (Ψm, Ψos) between disturbed and undisturbed areas. A large pool of salts and chlorides present in undisturbed areas was absent in disturbed plots, suggesting deep leaching. Unexpectedly, this was associated with slight but consistently lower SWC in disturbed versus undisturbed situations during two growing seasons. The apparent paradox of increased leaching but diminishing SWC after disturbance can be explained by the effect of native salt lowering Ψos enough to prevent full soil drying. Under disturbed conditions, the onset of deep drainage and salt leaching would raise Ψos allowing a decline of Ψm and SWC. Soil water storage seems to be modulated by the presence (under natural conditions) and partial leaching (following selective shrub disturbance) of large salt pools. This counterintuitive effect of disturbances may be important in semiarid regions where deep soil salt accumulation is a common feature. Our results highlight the importance of water-salt-vegetation coupling for the understanding and management of these systems.

Phenotypic plasticity as an index of drought tolerance in three Patagonian steppe grasses.

BACKGROUND AND AIMS: Despite general agreement regarding the adaptive importance of plasticity, evidence for the role of environmental resource availability in plants is scarce. In arid and semi-arid environments, the persistence and dominance of perennial species depends on their capacity to tolerate drought: tolerance could be given on one extreme by fixed traits and, on the other, by plastic traits. To understand drought tolerance of species it is necessary to know the plasticity of their water economy-related traits, i.e. the position in the fixed-plastic continuum. METHODS: Three conspicuous co-existing perennial grasses from a Patagonian steppe were grown under controlled conditions with four levels of steady-state water availability. Evaluated traits were divided into two groups. The first was associated with potential plant performance and correlated with fitness, and included above-ground biomass, total biomass, tillering and tiller density at harvest. The second group consisted of traits associated with mechanisms of plant adjustment to environmental changes and included root biomass, shoot/root ratio, tiller biomass, length of total elongated leaf, length of yellow tissue divided by time and final length divided by the time taken to reach final length. KEY RESULTS AND CONCLUSIONS: The most plastic species along this drought gradient was the most sensitive to drought, whereas the least plastic and slowest growing was the most tolerant. This negative relationship between tolerance and plasticity was true for fitness-related traits but was trait-dependent for underlying traits. Remarkably, the most tolerant species had the highest positive plasticity (i.e. opposite to the default response to stress) in an underlying trait, directly explaining its drought resistance: it increased absolute root biomass. The niche differentiation axis that allows the coexistence of species in this group of perennial dryland grasses, all limited by soil surface moisture, would be a functional one of fixed versus plastic responses.

Reacción de fototoxicidad por metotrexato / Photoxicity reaction due to methotrexate

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Potential growth and drought tolerance of eight desert grasses: lack of a trade-off?

Eight perennial C-4 grasses from the Jornada del Muerto Basin in southern New Mexico show five-fold differences in relative growth rates under well- watered conditions (RGRmax). In a controlled environment, we tested the hypothesis that there is an inverse relationship (trade-off) between RGRmax and the capacity of these species to tolerate drought. We examined both physiological (gas exchange) and morphological (biomass allocation, leaf properties) determinants of growth for these eight species under three steady-state drought treatments (none=control, moderate, and severe). When well watered, the grasses exhibited a large interspecific variation in growth, which was reflected in order-of-magnitude biomass differences after 5 weeks. The species had similar gas-exchange characteristics, but differed in all the measured allocation and morphological characteristics, namely tiller mass and number, root:shoot ratio, dry-matter content, and specific leaf area (SLA). Drought affected tillering, morphology, and allocation, and reduced growth by 50 and 68% (moderate and severe drought, respectively) compared to the well-watered controls. With the exception of SLA, none of these variables showed a significant species-by-treatment interaction. We calculated three indices of drought tolerance, defined as the ratio in final biomass between all the possible "dry"/"wet" treatment pairs: severe/moderate, moderate/control, and severe/control. We found no significant correlation between these drought tolerance indices, on the one hand, and three indices of growth potential (greenhouse RGRmax, final biomass in the control treatment, and final:initial biomass ratio in controls), on the other. Based on these controlled-environment results, we hypothesize that the commonly reported correlation between plant growth potential and drought tolerance in the field may in some cases be explained by differential effects of plants on soil-water content rather than by differences in species responses to drought.

Preoperative MR imaging in hyperparathyroidism: results and factors affecting parathyroid detection.

OBJECTIVE: To determine the sensitivity of MR imaging for the detection of abnormal parathyroid glands in patients with biochemical evidence of hyperparathyroidism and to identify the factors affecting detection. SUBJECTS AND METHODS: Between 1985, 82 patients with biochemical proof of hyperparathyroidism were referred for MR imaging of the parathyroid glands prior to surgery. Axial T1- (600/20 [TR/TE]) and T2-weighted (2500/40, 80) spin-echo images were obtained using an anterior neck surface coil. The interpretation of the MR image was compared with the findings at surgery and also correlated with gland histology, volume, and weight. Cases in which a false-positive or false-negative diagnosis was made were reviewed to determine the factors affecting detection. RESULTS: MR imaging detected 71 of 92 (77%) surgically proven abnormal glands (sensitivity, 77%; 95% confidence interval (CI), 68-86%) and misdiagnosed five (1.6%) of 314 normal glands as abnormal. There was no difference in the detection of enlarged glands in patients presenting for the first time (n = 71) (sensitivity, 77%; 95% CI, 66-86%) compared with patients with recurrent hyperparathyroidism (n = 12) (sensitivity, 77%; 95% CI, 46-95%). There was no significant difference in the detection of adenomas (sensitivity, 77%; 95% CI, 65-86%) compared with hyperplasia (sensitivity, 71%; 95% CI, 42-92%). Of five patients with ectopic parathyroid glands (1.6%), four had had previous surgery. All five glands were successfully located (three mediastinal, two in the neck). Factors contributing to a false-negative MR imaging diagnosis included small gland size and thyroid disease. Four of five false-positive diagnoses were due to enlarged lymph nodes being mistaken for parathyroid glands. CONCLUSIONS: MR imaging is an accurate technique for investigation of hyperparathyroidism. Pitfalls include low sensitivity for the identification of small glands, misinterpretation of enlarged lymph nodes as parathyroid adenomas, and misinterpretation because of thyroid disease. MR imaging is particularly useful in the investigation of patients who remain hypercalcemic following initial surgery.

Dressing wounds with potato peel.

The use of boiled potato peel (PP) in dressing of various skin conditions was studied. A total of 11 patients were selected, which included resistant wounds of pemphigus, bullous pemphigoid and leg ulcers. An autoclaved PP dressing with a thin layer of antiseptic cream was applied at 25 sites. It was covered with multilayered gauze and the dressing was secured firmly with either a roller bandage or with an adhesive tape. Complete epithelization was seen at 20 sites (80%), near complete epithelization at one site. There was no satisfactory response at three sites and at one site the result could not be evaluated. The mean duration of healing was one week for superficial wounds and three weeks for deep wounds. The PP dressing facilitates the wound and three weeks for deep wounds. The PP dressing facilitates the wound healing process by providing and maintaining a moist environment. The PP dressing is easy to prepare, apply as well as remove. It is a comfortable dressing and is also cost effective.

A study of geriatric dermatoses.

A total of 200 patients aged 55 years and above were studied for cutaneous changes associated with ageing. The majority of patients (66%) were found to be in the age group of 55 to 64 years, of these 63% were males and 37% females. Pruritus was the commonest complaint in 78.5%. A variety of cutaneous lesions were observed. The commonest were cherry angiomas, seborrhoeic keratosis and naevus cell naevi. Not a single case of cutaneous malignancy was seen. Only 34.5% of the total dermatoses were found to be of infective aetiology. Diabetes was the most commonly associated systemic ailment. A psychosomatic background was observed in nearly 9.5% of the cases.

Lichen simplex chronicus - A Psychocutaneous disorder?

Lichen simplex chronicus is classified as a skin disorder determined or influenced by emotional factors. This study was conducted to determine the involvement of the psyche in this psychocutaneous disorder. Forty six patients of lichen simplex chronicus were chosen for this study. The severity of pruritus was rated on a 10 point scale. They then underwent a psychiatric interview using the Hamilton anxiety-depression scale to quantitate their mental state. The numerical values of anxiety and depression did not exceed 50% of the measuring scale. This could be due to the 'venting' or exteriorisation of the inner turmoil, in this case by itching. The correlation between anxiety and pruritus and that of depression and pruritus was studied and it was surmised that depression may be related to pruritus compared to anxiety.

Clostridium septicum gas gangrene of the gluteus maximus and an ascending colon malignant tumor. A case report.

Clostridial myonecrosis is a complication associated with contaminated traumatized wounds. Presented is the case of an elderly female with pain in her right hip, radiographic evidence of gas in the soft tissues, and no history of trauma. Evaluation of this patient revealed Clostridial myonecrosis. Culture results identified the organism as Clostridium septicum. Due to the association between Clostridium septicum and occult malignancies, colonoscopic evaluation was performed. A colonic lesion was discovered, biopsied, resected, and staged, using the Modified Duke Classification, as a well differentiated adenocarcinoma, C2 lesion. Myonecrosis and its associated malignancies carry high morbidity and mortality, but early diagnosis, appropriate treatment, and awareness of the association with occult malignancies may avert unnecessary mortality.

Contrasting demography of two Patagonian shrubs under different conditions of sheep grazing and resource supply.

Two shrub species, dominant in western Patagonia, Argentina, exhibited different demographic behaviors under the effect of sheep grazing and of manipulated resource levels. Senecio filaginoides showed an increase in cover under increasing grazing pressures; the rise was explained by an increasing number of individuals and not by larger plants; this trend was reversed when no grazing took place. Mulinum spinosum showed a slight decrease in cover and density at increasing grazing pressures, and no change in plant size. In a field experiment in which water was added (30 mm in early summer) and the dominant grasses removed, both factors substantially augmented the number of 1-year-old seedlings of Senecio recruited; the only noticeable response of Mulinum was an increase in seedling emergence because of grass removal. Six years after this last treatment, Senecio exhibited a ten fold increase in density, and its population structure showed a peak in younger classes; Mulinum remained unaffected. In seedling surveys conducted within an exclsure and in its surroundings, the emergence of Senecio was similar in these areas in the two years of the study, whereas the emergence of Mulinum was higher inside the exclosure for one of the years. The emergence of Senecio in the wetter year was 3 times larger than in the drier one. Grazing did not affect first-year survival of any species; the major source of seedlign death in this case, as well as in the manipulative experiment, was desiccation during summer drought. We conclude that the contrasting responses of the two species to grazing are mostly due to the greater ability of Senecio to benefit from any increase in resources, including those not used by grazed plants. The difference might also be due to a reduction in the seed availability of Mulinum caused by sheep preference for its fruits. The dissimilar abilities of the two shrubs to employ the resources freed by grazing would derive more from their contrasting demographic potential (i.e. the ability to rapidly increase biomass/m2) than from a difference in their niche overlap with palatable species.

Rosoxacin in the treatment of uncomplicated acute gonococcal urethritis.

A total of 112 male patients presenting with acute gonococcal urethritis were admitted to the hospital. The diagnosis was confirmed by smear, culture, oxidase reaction and sugar fermentation tests. The patients were treated with a single 300 mg capsule of rosoxacin. All patients except one showed adequate response to rosoxacin.

Serological diagnosis of dengue by an Elisa inhibition method (EIM)

An ELISA Inhibition Method (EIM) was proposed for the serologic diagnosis of dengue, comparing its results with the Hemagglutination Inhibition (HI) and the IgM capture-ELISA (MAC-ELISA). Advantages and disadvantages of both methods are discussed according to sensitivity, specificity, performance and usefulness. As a conclusion we recommend the complementary inclusion of the EIM and MAC-ELISA substituting the HI for laboratories engaged in the diagnosis and surveillance of dengue

Serological diagnosis of dengue by an ELISA inhibition method (EIM).

An ELISA Inhibition Method (EIM) was proposed for the serologic diagnosis of dengue, comparing its results with the Hemagglutination Inhibition (HI) and the IgM capture-ELISA (MAC-ELISA). Advantages and disadvantages of both methods are discussed according to sensitivity, specificity, performance and usefulness. As a conclusion we recommend the complementary inclusion of the EIM and MAC-ELISA substituting the HI for laboratories engaged in the diagnosis and surveillance of dengue.

Clinical and mycological spectrum of cutaneous candidiasis in Bombay.

A total of 150 patients with cutaneous candidiasis were studied. A detailed clinical history was taken. Scrapings were examined in 10% KOH, and the material cultured on Sabouraud's agar. Species were identified by the serum germ tube test, sugar fermentation and sugar assimilation tests. Of 150 patients 79 were females. The commonest presentation was intertrigo (75), vulvovaginitis (19) and paronychia (17). A history of chronic exposure to water was obtained in 94 cases, all had erosio interdigitalis blastomycetica and/or paronychia. Diabetes melltius as a predisposing factor was observed in 22 patients. The 10 cases of balanoposthitis had associated diabetes mellitus. Smear and culture were positive in all the patients. C. albicans was isolated in 136 cases, C. tropicalis in 12, and C. guillermondi in 2. The cultures of C. albicans had positive serum germ tube test. The 6 patients in the paediatric age group having perianal/genital involvement had a stools culture positive for C. albicans.

Leg ulcer in a case of thalassemia minor (a case report).

A rare case of leg ulcer in a 28 years old woman with thalassemia minor is reported.

Pachyonychia Congenita.

Pachyonychia congenital is an infrequent genodermatosis, characterized by nail dystrophy, hyperkeratosis of the palms and soles, follicular keratosis and leukoplakia. It was seen in two male patients aged 12 and 35 years respectively. The younger patient had nail changes, palmo-planter keratoderma, eye changes, hypotrichosis and mental retardation, while the elder one had minimal nail changes, keratoderma and leukoplakia.