Increase in phosphorus losses from grassland in response to Olsen-P accumulation.

The Olsen-P status of grazed grassland (Lolium perenne L.) swards in Northern Ireland was increased over a 5-yr period (March 2000 to February 2005) by applying different rates of P fertilizer (0, 10, 20, 40, or 80 kg P ha(-1) yr(-1)) to assess the relationship between soil P status and P losses in land drainage water and overland flow. Plots (0.2 ha) were hydrologically isolated and artificially drained to v-notch weirs, with flow proportional monitoring of drainage water and overland flow. Annually, the collectors for overland flow intercepted between 11 and 35% of the surplus rainfall. Single flow events accounted for up to 52% of the annual dissolved reactive phosphorus (DRP) load. The Olsen-P status of the soil influenced DRP and total phosphorus (TP) concentrations in land drainage water and overland flow. Annual TP loss was highly variable and ranged from 0.19 to 1.55 kg P ha(-1) yr(-1) for the plot receiving no P fertilizer and from 0.35 to 2.94 kg P ha(-1) yr(-1) for the plot receiving 80 kg P ha(-1) yr(-1). Despite the Olsen-P status in the soils ranging from 22 to 99 mg P kg(-1), after 5 yr of fertilizer P applications it was difficult to identify a clear Olsen-P concentration at which P losses increased. Any relationship was confounded by annual variability of hydrologic events and flows and by hydrologic differences between plots. Withholding P fertilizer for over 5 yr was not long enough to lower P losses or to have an adverse effect on herbage P concentrations.

Halting the upward trend in soluble phosphorus transported from a grassland catchment.

An upward trend in soluble reactive phosphorus (SRP) concentrations in Northern Ireland rivers leading to increased eutrophication has been reported for the last two decades. To identify if a similar trend could be observed in land drainage waters SRP and other P fractions were measured weekly from 1989 to 1997 in land drainage from a 9-ha grassland catchment in Northern Ireland that had a mean P surplus applied of 23.4 kg P ha(-1) yr(-1). Regressions of annual median concentrations of P fractions in land drainage waters against time for 1989 through to 1997 showed significant increases of SRP and soluble unreactive phosphorus (SUP) of 2.4 and 1.2 microg P L(-1) yr(-1), respectively. However, the annual flow-weighted concentrations and loads of all P fractions did not show significant increases with time. During the period 1998-2000 a change of management was introduced when only maintenance dressings of P were applied to the catchment according to Ministry of Agriculture, Fisheries and Food guidelines. This resulted in significant reductions in SRP concentrations in 2000 compared with 1997.

Early wound complications in advanced head and neck cancer treated with surgery and Ir 192 brachytherapy.

OBJECTIVES: Brachytherapy, either as primary or adjuvant therapy, is increasingly used to treat head and neck cancer. Reports of complications from the use of brachytherapy as adjuvant therapy to surgical excision have been limited and primarily follow Iodine 125 (I125) therapy. Early complications include wound breakdown, infection, flap failure, and sepsis, and late complications may include osteoradionecrosis, bone marrow suppression, or carotid injuries. The authors sought to identify the early wound complications that follow adjuvant interstitial brachytherapy with iridium 192 (IrS92). STUDY DESIGN: A retrospective chart review of all patients receiving adjuvant brachytherapy at a tertiary medical center over a 4-year period. METHODS: Nine patients receiving Ir192 brachytherapy via afterloading catheters placed during surgical resection for close or microscopically positive margin control were evaluated. It was used during primary therapy in six patients and at salvage surgery in three. Early complications were defined as those occurring within 6 weeks of surgical therapy. RESULTS: The overall complication rate was 55% (5/9), and included significant wound breakdown in two patients, minor wound dehiscence in three, and wound infection, bacteremia, and local tissue erosion in one patient each. All complications occurred in patients receiving flap reconstruction and one patient required further surgery to manage the complication. Complication rates were not associated with patient age, site, prior radiotherapy, timing of therapy, number of catheters, or dosimetry. CONCLUSIONS: The relatively high complication rate is acceptable, given the minor nature of most and the potential benefit of radiotherapy. Further study should be undertaken to identify those patients who will achieve maximum therapeutic benefit without prohibitive local complications.

Close or positive margins after surgical resection for the head and neck cancer patient: the addition of brachytherapy improves local control.

PURPOSE: Microscopically positive or close margins after surgical resection results in an approximately 21-26% local failure rate despite excellent postoperative external radiation therapy. We sought to demonstrate improved local control in head and neck cancer patients who had a resection with curative intent, and had unexpected, microscopically positive or close surgical margins. METHODS AND MATERIALS: Twenty-nine patients with microscopically close or positive margins after curative surgery were given definitive, adjuvant external radiation therapy and 125I brachytherapy. All 29 patients had squamous cell cancer and tonsil was the most common subsite within the head and neck region. After external radiation therapy and thorough discussions with the attending surgeon and pathologists, the slides, gross specimens, and appropriate radiographs were reviewed and a target volume was determined. The target volume was the region of the margin in question and varied in size based on the surgery and pathologic results. Once the target volume was identified the patient was taken back to the operating room for insertion of 125I seeds. Activity implanted (range 2.9-21.5 millicuries) was designed to administer a cumulative lifetime dose of 120-160 Gy. RESULTS: Twenty-nine patients were followed for a median of 26 months (range 5-86 months). Two-year actuarial local control was 92%. CONCLUSION: 125I, after external radiation therapy, is an excellent method to improve local control in the subset of patients with unexpectedly unsatisfactory margins.

Microbial models of mammalian metabolism.

A solid basis for the M4-approach has been developed over the past 10 years. Recent examples of the production of difficult-to-synthesize mammalian metabolites through microbial transformations attest to the utility of the methodology. There is, however, much more to be done. Model studies should be conducted to test parallels between microbial and mammalian S- and N-oxidations, O-glucuronidations, and ester and amide hydrolyses. Subsequently, even greater applications of M4- work can be envisioned. We have been pleased to see our colleagues in industry and academia adopt the M4- approach to solve difficult pharmacological and toxicological problems. In large measure, this has been our greatest reward for efforts initially presented before the membership of the American Society of Pharmacognosy in 1973.

Plasma levels of apomorphine following intravenous, intraperitoneal and oral administration to mice and rats.

Clinical use of the potent dopaminergic partial-agonist apomorphine (APO) in a wide variety of neuropsychiatric disorders is hampered by a lack of data concerning tissue/plasma levels following various routes of administration. In the present experiments, plasma levels were assessed at various times up to 4 hours after APO administration IV, IP, and PO to mice and rats. Plasma levels of total radioactivity after PO administration of [3H]-APO were 50 to 65% of those seen after IV administration, but brain levels were almost undetectable after PO administration. Organic solvent-extractable concentrations of tritium-labelled material after IV and IP administration of [3H]-APO to mice were significantly lower than the levels of total radioactivity, while after PO administration, these concentrations were minimal. Similar results were observed in rats following IV and PO administration of [3H]-APO.