Phytoplankton biomass and composition in a well-flushed, sub-tropical estuary: The contrasting effects of hydrology, nutrient loads and allochthonous influences.

The primary objective of this study was to examine trends in phytoplankton biomass and species composition under varying nutrient load and hydrologic regimes in the Guana Tolomato Matanzas estuary (GTM), a well-flushed sub-tropical estuary located on the northeast coast of Florida. The GTM contains both regions of significant human influence and pristine areas with only modest development, providing a test case for comparing and contrasting phytoplankton community dynamics under varying degrees of nutrient load. Water temperature, salinity, Secchi disk depth, nutrient concentrations and chlorophyll concentrations were determined on a monthly basis from 2002 to 2012 at three representative sampling sites in the GTM. In addition, microscopic analyses of phytoplankton assemblages were carried out monthly for a five year period from 2005 through 2009 at all three sites. Results of this study indicate that phytoplankton biomass and composition in the GTM are strongly influenced by hydrologic factors, such as water residence times and tidal exchanges of coastal waters, which in turn are affected by shifts in climatic conditions, most prominently rainfall levels. These influences are exemplified by the observation that the region of the GTM with the longest water residence times but lowest nutrient loads exhibited the highest phytoplankton peaks of autochthonous origin. The incursion of a coastal bloom of the toxic dinoflagellate Karenia brevis into the GTM in 2007 demonstrates the potential importance of allochthonous influences on the ecosystem.

Effect of short ray trajectories on the scattering statistics of wave chaotic systems.

In many situations, the statistical properties of wave systems with chaotic classical limits are well described by random matrix theory. However, applications of random matrix theory to scattering problems require introduction of system-specific information into the statistical model, such as the introduction of the average scattering matrix in the Poisson kernel. Here, it is shown that the average impedance matrix, which also characterizes the system-specific properties, can be expressed in terms of classical trajectories that travel between ports and thus can be calculated semiclassically. Theoretical results are compared with numerical solutions for a model wave chaotic system.

Two-component systems in Haemophilus influenzae: a regulatory role for ArcA in serum resistance.

Knockout mutations were constructed in the arcA gene of a virulent type b strain of Haemophilus influenzae, and the behavior of the resulting mutants was investigated in a number of conditions that mimicked distinct steps in the natural infection pathway. In arcA mutants, synthesis of capsule and lipooligosaccharide (LOS) and growth in synthetic media were unaltered compared to synthesis of capsule and LOS and growth in synthetic media in the wild-type H. influenzae type b parent strain. However, the virulence of the arcA mutants for BALB/c mice was significantly reduced. Upon exposure to human blood or serum, the arcA mutants showed markedly reduced survival compared with the survival of its wild-type parent. Serum resistance could be fully restored by complementation in cis with the H. influenzae arcA gene but not by complementation in cis with the homologous gene from Escherichia coli. The proteomes of wild-type and mutant bacteria were markedly different, especially under anaerobic conditions, underscoring the global regulatory role of ArcAB in H. influenzae. Evaluation of antibody titers and classical complement activities in various serum samples pointed to complement-mediated bactericidal activity as the factor that distinguishes between the arcA mutant and wild-type phenotypes. Comparative analysis of the membrane fractions of the arcA mutants and the wild-type strain revealed several ArcA-regulated proteins, some of which may be implicated in the serum hypersensitivity phenotype.

Bacteriologic and histologic features in mice after intranasal inoculation of Brucella melitensis.

OBJECTIVE: To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice. ANIMALS: Female Balb/c mice, 6 to 8 weeks old. PROCEDURE: Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy. RESULTS: Measurable splenomegaly was evident at 3 and 7 weeks after inoculation. A demonstrable increase in splenic colony-forming units (CFU) from infected mice increased over time with increasing dose when comparing inocula of 10(3), 10(4), and 10(5) CFU. Recovery of brucellae from the lungs was possible early in infection with 10(1), 10(3), and 10(5) CFU, but only the group inoculated with 10(5) CFU consistently yielded quantifiable bacteria. At a dose of 10 CFU, few organisms were located in the spleen. Bacteria were recovered up to 140 days after inoculation in mice given 10(3) CFU. At an inoculum of 10(5) CFU, bacterial counts were highest early in infection. Histologic examination of tissues revealed an increase in white pulp and marginal zone in the spleen and lymphohistiocytic hepatitis. CONCLUSION AND CLINICAL RELEVANCE: Changes in the spleen and liver increased with increases in dose and with increased time following intranasal inoculation with B melitensis 16M. Surprisingly, histologic changes were not observed in the lungs of inoculated mice.

Active variants of human parathyroid hormone (1-34) with multiple amino acid substitutions.

We used site-directed mutagenesis to construct 55 single-site variants of rhPTH, a recombinantly-expressed form of human parathyroid hormone (1-34) containing three amino acid changes compared to the natural sequence (ML8, ML18 and FY34). We identified several mutations, at residues Lys(13), Glu(19), Val(21), Glu(22), Lys(27) and Asp(30), that increase biological activity by up to 2. 5-fold, as measured by stimulation of adenylate cyclase activity in rat UMR-106 cells. We constructed a series of 15 variants in which two to eight substitutions at these positions were combined, and found that the mutations behaved additively, leading to peptides with significantly enhanced potency. The most active combination variant, with six substitutions (KS13, ES19, VQ21, ES22, KQ27 and DN30), is 15 times more active than the parent molecule. However, the extent to which such combinations increase the activity of the peptide depends critically on the identity of the residues at positions 8 and 18. We constructed two of the combination variants in a variety of sequence backgrounds containing different combinations of leucine, methionine and norleucine at positions 8 and 18. Enhancements in potency were significantly reduced when Met or Nle was present at either of these positions, both in UMR-106 cells and human SaOS-2 cells. A corresponding non-additivity was observed in direct measurements of receptor binding affinity on UMR-106 cells. These results suggest that interactions, either direct or indirect, between certain PTH side chains prevent these mutations from behaving in an additive manner.

The surgeon and casemix.

Casemix funding has markedly increased surgeons' awareness of the economies of the activities they undertake. Surgery has become a major focus at all large public hospitals, because of its high earning potential, and this pressure to maximise funding could influence surgical practice. Casemix funding's emphasis on length of hospital stay has encouraged forward planning for earlier discharge after surgical procedures. Patients are now assessed in pre-admission clinics, educated about their condition and their hospital stay, and a plan formulated for their discharge and rehabilitation. Funding for major surgical procedures of long duration in patients with complex conditions should reflect the higher level of resource utilisation. Tertiary referral centres, because of their commitment to training and research and their more severely ill patient population, are less cost-effective and require funding to ensure their viability. The improved information that casemix generates should be used to evaluate outcomes and improve patient care; efficiency must not take precedence over quality of care and compassion.

The efficacy of intra-articular morphine for postoperative knee arthroscopy analgesia.

This article describes two prospective, randomized, double-blind clinical trials designed to investigate this. Trial 1 compared a conventional local anaesthetic agent (100 mg bupivacaine) injected intra-articularly (i.a.) with a control (normal saline) and 1 mg of i.a. morphine. No significant difference was noted in the first 4 hours between the groups with respect to visual analogue pain (VAS) scores. However, at 6 and 24 hours, the group of patients who received 1 mg i.a. morphine recorded lower pain scores and required less supplementary analgesia. Trial 2 assessed the dose response relationship for i.a. morphine comparing 5 mg intravenous (i.v.) morphine (control) with 1 mg and 5 mg i.a. morphine. At early time points (1, 2, and 4 hours) similar VAS pain scores were recorded for both 5 mg i.v. morphine and 5 mg i.a. morphine, both significantly lower than the group receiving 1 mg i.a. morphine. At 6 and 24 hours, 5 mg of i.a. morphine produced significantly lower pain scores, less analgesic requirement, and less sleep disturbance on the first postoperative night than the other groups. It can be concluded from these two studies that 5 mg i.a. was the most effective analgesic following knee arthroscopy.

Identification of residues critical to the activity of human granulocyte colony-stimulating factor.

Alanine scanning mutagenesis of human granulocyte colony-stimulating factor (G-CSF) was used to identify residues critical for the cell-proliferative activity of the protein. Fifty-eight residues, most of them on the protein surface, were independently mutated to alanine. Most of the variants retained full biological activity; however, 15 mutants were significantly impaired in their ability to stimulate bone marrow cell proliferation in vitro. Four of these variants contain mutations at buried residues and two have substitutions at side chains involved in intramolecular hydrogen bonds. The remaining nine down mutations identify two regions on the surface of the molecule important for biological activity. Consistent with these observations, measurements of binding to NFS-60 cells indicate that the residues most important for receptor binding are Lys40 and Phe144 in site 1 and Glu19 in site 2. In addition to these residues, Val48 and Leu49 in site 1 and Leu15, Asp112, and Leu124 in site 2 are also important for biological activity. These results suggest the presence of two binding sites on the cytokine surface required for dimerization of the G-CSF receptor.

L-trans-2,3-pyrrolidine dicarboxylate: characterization of a novel excitotoxin.

This study investigated the in vitro and in vivo excitotoxic properties of a novel conformationally constrained analogue of L-glutamate, L-trans-2,3-pyrrolidine dicarboxylate (L-trans-2,3-PDC). When tested for excitotoxic activity in rat cortical cultures, L-trans-2,3-PDC mimicked the action of NMDA in both acute (30 min) and chronic (24 h) exposure paradigms. This neurotoxicity was attenuated by co-addition of MK-801 (10 microM). Microinjections of L-trans-2,3-PDC into the dorsal hippocampus of male rats also induced a selective pattern of pathology indicative of an NMDA receptor excitotoxin. In contrast to the equipotency observed in vitro, 100 nmol of L-trans-2,3-PDC were needed to produce cellular damage comparable to that induced by 25 nmol of NMDA. Consistent with an action at NMDA receptors, L-trans-2,3-PDC-induced damage could be significantly reduced by co-administration of MK-801 (3 mg/kg i.p.), but not by NBQX (25 nmol). In radioligand binding assays L-trans-2,3-PDC inhibited the binding of 3H-L-glutamate to NMDA receptors (IC50 1 microM), although it also exhibited some cross reactivity with KA and AMPA receptors. L-trans-2,3-PDC was also identified as a competitive inhibitor (Ki = 33 microM) of 3H-D-aspartate uptake into rat forebrain synaptosomes. In contrast to the action of a transported substrate, such as L-glutamate, L-trans-2,3-PDC did not exchange with 3H-D-aspartate that had been previously loaded into the synaptosomes.

Treatment outcome of major fractures of the talus.

Twenty-six patients with major fractures of the talus were studied to assess the long-term outcome. The patients were admitted to a university teaching hospital and major trauma center from 1983 to 1991. The study excluded isolated fractures of the talar dome and posterior tubercle. Fifteen patients were treated using internal fixation and 11 patients were treated using nonsurgical methods. Avascular necrosis was detected in only four of the 26 patients. Subtalar osteoarthritis was a significant problem in 61%. Seven of these patients have come to secondary fusion procedures, with another three contemplating fusion procedures at the time of review. Only one patient developed significant avascular necrosis requiring a fusion procedure. Only three of 26 patients had not returned to work at a mean 6 years after their injury. Eleven of the 26 (42%) had not returned to their premorbid activity level. The majority of these patients (25/26) had sustained multiple injuries, which compromised the functional recovery from the talar injury. Early accurate diagnosis and anatomical reduction gave the best results. The low incidence of avascular necrosis in this study has been attributed to early anatomical stabilization of the fracture. We believe an early CT scan can more accurately assess the severity of the talar fracture and offers the best information for an appropriate treatment plan.

Preoperative autologous blood donation. Linkage of the public and private hospital sectors.

OBJECTIVE: To evaluate the safety and efficacy of a preoperative autologous blood donation (PABD) program with liberal patient exclusion criteria. DESIGN: Prospective patient accrual from September 1990 to May 1992. SETTING: A PABD program in a public tertiary care hospital linked with a specialist orthopaedic practice in a private hospital. PATIENTS: One hundred and twenty patients consecutively scheduled for orthopaedic surgery were referred for PABD. There were 77 women (median age, 63 years) and 43 men (median age, 62 years). One-third of patients were 70 or more years old. Coexistent medical disease, mainly cardiovascular, was present in 46% of patients and 3% were excluded because of coexisting morbidity. Total hip or total knee replacement was performed in a private hospital with intraoperative or postoperative blood salvage in 37% of the patients. OUTCOME MEASURES: Adverse effects of PABD, autologous blood collected and used and homologous blood transfused. RESULTS: One hundred and sixteen patients donated 267 units of autologous blood. In 70 patients undergoing total hip replacement, 78% donated three and 20% donated two units, with 95% of autologous blood being used. In 38 patients undergoing total knee replacement, 42% donated two units and 55% donated one unit, with 87% of autologous blood being transfused. Seventy-eight per cent of all patients only received autologous blood. In the remaining patients, homologous blood use was confined to two units or less in 80%. Hypotensive episodes associated with phlebotomy occurred in 3% of patients, and 13% of patients had preoperative haemoglobin levels ranging from 85-100 g/L without adverse clinical effects. CONCLUSION: A hospital-based PABD program with less strict patient exclusion criteria does not prejudice the clinical status of the donors. Its linkage to private hospitals can significantly reduce the use of homologous blood in selected elective surgery.

Case Study: Rehabilitation of a Surgically Repaired Medial Collateral Knee Ligament Using a Limited Motion Cast and lsokinetic Exercise*.

Recent studies indicate that early mobilization of surgically repaired collateral ligaments leads to a more rapid gain in tensile strength compared to immobilized ligaments. Other advantages of early mobilization include prevention of muscle atrophy, joint stiffness, and articular cartilage fibrillation. Because of these observations, a professional Australian Rules footballer with a complete rupture of the right medial collateral ligament of his knee joint, was commenced, after surgical repair, on an early controlled mobilization program using a limited motion cast (LMC) and isokinetic exercise. Rehabilitation was commenced after 2 weeks of immobilization in a LMC, and progressed through four stages, all coupled with isokinetic exercise. Weeks 2-6, exercise in LMC through 20-60 degrees ; weeks 7-8, exercise out of LMC through 15- 1 OOO; weeks 8-9, exercise through a full range of movement, 0-130'; weeks 10- 12, exercise through a full range plus inner range 0-30' repetitions. The footballer returned to full competition approximately 12 weeks postsurgery with no medial collateral laxity and almost normal Cybex IP parameters. J Orthop Sports Phys Ther 1986;7(4):154-158.

A study of the relationship between the pharmacokinetics and the pharmacodynamics of the 4-hydroxycoumarin anticoagulants warfarin, difenacoum and brodifacoum in the rabbit.

The pharmacokinetics and pharmacodynamics of the 4-hydroxycoumarin anticoagulants, brodifacoum, difenacoum, and warfarin have been studied in the rabbit. Sensitive (50 ng ml-1) and specific high performance liquid chromatography assays have been developed for the determination of plasma concentrations of warfarin, brodifacoum and difenacoum. After administration of a single intravenous dose (20 mumol kg-1), plasma concentrations of warfarin underwent mono-exponential decay, with a terminal half-life of 5.6 +/- 0.7 h (mean +/- s.e. mean), whereas plasma concentrations of brodifacoum and difenacoum underwent bi-exponential decay with terminal half-lives of 60.8 +/- 1.9 h and 83.1 +/- 10.3 h respectively. The plasma half-life of brodifacoum in a single patient poisoned with the compound was 487 h. The pharmacological response to the anticoagulants was measured as changes in prothrombin complex activity, from which the rate of clotting factor synthesis was determined. Clotting factor synthesis recovered in a monophasic fashion after a single intravenous dose of warfarin, compared with a more complex biphasic, pattern of recovery of clotting factor synthesis after administration of either brodifacoum or difenacoum. The slope (m) of the intensity of effect-log (amount of drug in the body) curve was derived for each anticoagulant. There was no significant difference in the value of m after single intravenous doses of racemic, R-, and S-warfarin, difenacoum and brodifacoum, which is consistent with the hypothesis that all the 4-hydroxycoumarin anticoagulants produce their anticoagulant effect by acting at the same receptor site, vitamin K epoxide reductase. Determination of the minimum plasma concentration of each anticoagulant that corresponded with the complete inhibition of clotting factor synthesis indicated that racemic warfarin, R-warfarin and brodifacoum have similar potencies in the rabbit and are less potent than S-warfarin and difenacoum.

The urethral catheter--a review of its implication in urinary-tract infection.

The research into acquisition of urinary-tract infection over the last few decades has established three ways in which organisms may gain access to the urinary tract of the catheterized patients: Firstly, during the process of passing the catheter into the bladder should complete asepsis not be observed; secondly by travelling along the urethra in the small, fluid-filled cavity between catheter and mucosa; Thirdly following contamination of the drainage system, along the inside of the catheter directly into the bladder. The relative importance of each route is not clear and is still the subject of much controversy but it would seem that all these routes have a part to play in allowing infection to develop. The risk of catheterized patients acquiring urinary-tract infection is so great that where possible catheterization should be avoided. The most important preventive measure which may be taken is to limit the duration of indwelling catheterization. In addition, a considerable amount of research has attempted to distinguish other factors which might affect the rate at which urinary-tract infection in the catheterized patient becomes established so that high-risk patients may be identified. The evidence indicates that the risk increases with duration of catheterization, age, length of hospital stay, immunosuppressant treatment, that it is greater in female than male patients and that a patient with a serious or fatal underlying disease is also more likely to develop bacteriuria. Finally, properties of the urine and the host defence mechanisms may affect the susceptibility of the individual to urinary-tract infection. Identification of the routes of infection and patients at risk is only part of the problem. The next stage is to formulate criteria for the care of catheterized patients which reduce the risk of infection to the absolute minimum and will hopefully go some way towards diminishing the unsatisfactory high levels of urinary-tract infection that are currently associated with indwelling catheterization.

A study of factors which determine the pharmacological response to vitamin K in coumarin anticoagulated rabbits.

The pharmacological response to vitamin K has been determined by measuring prothrombin complex activity (P.C.A.) in male New Zealand White rabbits anticoagulated (P.C.A. less than 20%) with the long acting 4-hydroxycoumarin brodifacoum, at a dose (10 mg/kg) which produces maximum antagonism of vitamin K1. Thus, according to current concepts, this animal model may be used to assess vitamin K requirements in the absence of a functional vitamin K-epoxide reductase. After intravenous administration of vitamin K1 (1 mg/kg) P.C.A. reached a maximum (64 +/- 19%) at 3 hr and then declined at a rate which corresponds to complete inhibition of clotting factor synthesis. Vitamin K2 (1 mg/kg) stimulated clotting factor synthesis for 2 hr, while cis-vitamin K1, vitamin K3, vitamin K1 2,3-epoxide and oral administration of vitamin K1 were ineffective. Plasma concentrations of vitamin K1 fell steeply during the 12 hr following administration of a pharmacological dose, and then declined with a terminal half-life of 18.9 +/- 9.0 hr. Comparison of the pharmacodynamic and pharmacokinetic data indicated that plasma concentrations in the range 0.4-1.0 microgram/ml are required for clotting factor synthesis in the limiting situation of maximum antagonism of vitamin K by coumarin anticoagulants. These findings explain why frequent and repeated administration of vitamin K1 may be necessary during coumarin poisoning.