Bioaccumulation and clearance of microcystins from salt water mussels, Mytilus edulis, and in vivo evidence for covalently bound microcystins in mussel tissues

Over a period of 3 days saltwater mussels, Mytilus edulis, were fed a cyanobacteria, Microcystis aeruginosa, that contained a high concentration of microcystins. The mussels were killed on a periodic basis over the course of 2 months. Mussels were also collected at two sites were high levels of microcystins in tissues had been noted. A strategy based on the chemically unique nature of the C20 beta-amino acid, (2S,3S,8S,9S)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6- dienoic acid (Adda), portion of the microcystins was used in conjunction with a protein phosphatase (PPase) assay to analyse for both covalently bound microcystins and free microcystins in the mussel tissues. The mussel PPase assay results were compared with the Lemieux oxidation gas chromatography-mass spectrometry (GCMS) analysis. Less than 0.1% of the total microcystin burden in the mussel tissue was found to be extractable with MeOH. Thus, direct evidence was provided for the existence of covalently bound microcystins in mussel tissues in vivo. The mussels rapidly cleared the covalently bound microcystins when transferred to untreated seawater. Within 4 days the total microcystin burden dropped from a high of 336.9 (+/- 45.8) micrograms/g wet tissue to 11.3 (+/- 2.6) micrograms/g. After 4 days postexposure until completion of the experiment the total levels remained below the detection limits of the GCMS method. The levels of free microcystins, extracted with MeOH and detected by the PPase assay, fell from 204 ng/g wet tissue to a residual 14 ng/g over a 53 day postexposure period. Presumably the bound microcystin present in the mussel tissue exists as a covalent complex with the PP-1 and PP-2A enzymes. We conclude that in any shellfish monitoring program it is the total tissue microcystin burden that needs to be considered.

Bispecific monoclonal antibody complexes facilitate erythrocyte binding and liver clearance of a prototype particulate pathogen in a monkey model

We used Anger camera imaging in a monkey model to investigate the organ localization of a prototype particulate pathogen, 131I-labeled bacteriophage phi X174, after it was bound to the primate erythrocyte complement receptor and then cleared from the circulation. This 131I-labeled phi X174 was infused into the circulation of an immunized monkey, and the nascently formed immune complexes showed rapid and quantitative binding to erythrocytes via the immune adherence reaction (complement-mediated binding). Alternatively, phi X174 was infused into the circulation of a naive animal, and then cross-linked bispecific mAb complexes (heteropolymers, anti-CR1 x anti-phi X174) were infused into the circulation. The infused heteropolymers also facilitated rapid and quantitative binding of phi X174 to erythrocytes. In both cases, after a short lag period, the erythrocyte-bound phi X174 was rapidly cleared from the circulation, and the vast majority of the radiolabel was cleared to the liver, with a small amount clearing to the spleen. Further liver imaging confirmed that within 24 h most of the bacteriophage previously cleared to the liver via the heteropolymer system was phagocytosed and destroyed. The findings in this model system provide additional evidence for the potential utility of heteropolymers to facilitate the safe and rapid clearance of blood-borne pathogens as a potential treatment for infectious diseases.

Bispecific monoclonal antibody complexes facilitate erythrocyte binding and liver clearance of a prototype particulate pathogen in a monkey model

We used Anger camera imaging in a monkey model to investigate the organ localization of a prototype particulate pathogen, 131I-labeled bacteriophage phi X174, after it was bound to the primate erythrocyte complement receptor and then cleared from the circulation. This 131I-labeled phi X174 was infused into the circulation of an immunized monkey, and the nascently formed immune complexes showed rapid and quantitative binding to erythrocytes via the immune adherence reaction (complement-mediated binding). Alternatively, phi X174 was infused into the circulation of a naive animal, and then cross-linked bispecific mAb complexes (heteropolymers, anti-CR1 x anti-phi X174) were infused into the circulation. The infused heteropolymers also facilitated rapid and quantitative binding of phi X174 to erythrocytes. In both cases, after a short lag period, the erythrocyte-bound phi X174 was rapidly cleared from the circulation, and the vast majority of the radiolabel was cleared to the liver, with a small amount clearing to the spleen. Further liver imaging confirmed that within 24 h most of the bacteriophage previously cleared to the liver via the heteropolymer system was phagocytosed and destroyed. The findings in this model system provide additional evidence for the potential utility of heteropolymers to facilitate the safe and rapid clearance of blood-borne pathogens as a potential treatment for infectious diseases.

14C-labeled microcystin-LR administered to Atlantic salmon via intraperitoneal injection provides in vivo evidence for covalent binding of microcystin-LR in salmon livers

The tissue distribution and clearance of radiolabeled microcystin-LR administered to Atlantic salmon via i.p. injection has been re-examined using uniformly 14C-labeled toxin. Significant differences were found to exist between these results and those obtained when fish received an i.p. injection of tritium-labeled dihydromicrocystin-LR. In addition, MeOH liver extracts were assayed by both phosphatase assay and 14C counts and the results compared with the total levels of incorporation determined by digestion and subsequent 14C counting of the same live tissues. An attempt to investigate the metabolism and to document the putative products was also undertaken. It was found that microcystin-LR was extensively metabolized to compounds that are more polar than the parent compound.

Evidence for a covalently bound form of microcystin-LR in salmon liver and Dungeness crab larvae

The chemically unique nature of the C20 beta-amino acid (2S,3S,8S,9S)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6- dienoic acid (Adda) portion of the microcystins has been exploited to develop a strategy to analyze for the total microcystin-LR (1; see Figure 1) burden in salmon liver and crab larvae tissues. Lemieux oxidation of microcystin-LR (1) gives 2-methyl-3-methoxy-4-phenylbutanoic acid (2), a unique marker for the presence of microcystins. The butanoic acid 2 can be isolated and detected by GC/MS from the livers of Atlantic salmon that received an ip injection of microcystin-LR (1) and from tissues of wild-caught crab larvae. The Lemieux oxidation-GC/MS results are compared with those from MeOH extraction-PPase analysis. Only approximately 24% of the total microcystin-LR (1) burden in salmon liver tissue is found to be extractable with MeOH. Similarly, the Lemieux oxidation-GC/MS method detected 10,000-fold greater microcystin concentrations in Cypress Island Dungeness crab larvae than did the MeOH extraction-PPase method. The disparity in microcystin concentrations measured by the two methods is taken as direct evidence for the existence of covalently bound microcystins in vivo.

Molecular mechanisms underlying he interaction of motuporin and microcystins with type-1 and type-2A protein phosphatases

Heptapeptide microcystin and pentapeptide motuporin (nodularin-V) are equipotent inhibitors of type-1 and type-2A protein phosphatase catalytic subunits (PP-1c and PP-2Ac). Herein we describe elucidation of the molecular mechanisms involved in the interaction of these structurally similar hepatotoxins with PP-1c/PP-2Ac and identification of an important functional difference between their mode of interaction with these enzymes. Microcystin-LR, microcystin-LA, and microcystin-LL were found to interact with PP-2Ac and PP-1c by a two-step mechanism involving rapid binding and inactivation of the protein phosphatase (PPase) catalytic subunit, followed by a slower covalent interaction (within hours). Covalent adducts comprising PPase-toxin complexes were separated from free PPase by C-18 reverse-phase liquid chromatography, thus allowing the time course of covalent adduct formation to be quantitated. In contrast to microcystins, motuporin (nodularin-V) and nodularin-R were unable to form covalent complexes with either PP-1c or PP-2Ac even after 96 h incubation. Specific reduction of microcystin-LA to dihydromicrocystin-LA abolished the ability of the toxin to form a covalent adduct with PP-2Ac. Specific methyl esterification of the single Glu residue in microcystin-LR rendered this toxin inactive as a PPase inhibitor and abolished subsequent formation of a covalent adduct. Our data indicate that inactivation of PP-2Ac/PP-1c by microcystins precedes covalent modification of the PPases via a Michael addition reaction between a nucleophilic phosphatase residue and Mdha in the heptapeptide toxin. In contrast, following rapid inactivation of PP-2Ac/PP-1c by motuporin, the equivalent N-methyldehydrobutyrine residue in this toxin is unreactive and does not form a covalent bond with the PPases. These results are consistent with structural data for (i) the NMR solution structures of microcystin-LR and motuporin, which indicate a striking difference in the relative positions of their corresponding dehydroamino acids in the toxin peptide backbone, and (ii) X-ray crystallographic data on an inactive complex between PP-1c and microcystin-LR, which show a covalent bond between Cys-273 and the bound toxin.

Volunteer services

Hospice volunteers can be the link between professional staff and members of a family suffering the impending loss of a loved one. By helping with practical needs and providing emotional support, volunteers may serve a crucial role in the healing of the grieving family.

Nonconvex hulls for mineral reflectance spectra

Linear programming is shown to be a powerful tool for the analysis of mineral reflectance spectra. Algorithms are described, first for stripping the background shape from the diagnostic pattern of narrow absorption features and then for characterizing the main residual features in terms of position, depth, and width. The expected application is automatic recognition of mineral species encountered in mining and exploration contexts, whether for analysis of drill core or for use in smart, field-portable spectrometers.

Identification and characterization of hydrophobic microcystins in Canadian freshwater cyanobacteria

Hepatotoxic microcystins produced by cyanobacteria in freshwater lakes represent a significant health hazard to humans and agricultural livestock. Liquid chromatography (LC)-linked protein phosphatase (PPase) bioassay analysis of blooms of Microcystis aeruginosa produced in a Canadian drinking water lake identified several PPase inhibitors with significantly greater hydrophobicity than microcystin-LR, based on their retention time on C18 reverse phase LC columns. Seven PPase inhibitors were purified to homogeneity by bioassay-guided fractionation involving Sephadex LH-20 chromatography and two-step reverse phase at pH 6.5 and 2.0. One of the PPase inhibitors, isolated in a final yield of 1.5 micrograms/g lyophilized cyanobacteria, was identified as microcystin-LL by amino acid analysis and mass spectrometry. A further PPase inhibitor (20 ng/g cyanobacteria) was identified as microcystin-LL but with D-Ala replaced by an unknown amino acid. Four PPase inhibitors (< 20 ng/g cyanobacteria) were characterized by amino acid analysis and identified as microcystin-LV, -LM, -LF and -LZ (where Z represents an unknown hydrophobic amino acid). A further microcystin was also identified (< 10 ng/g cyanobacteria) in which arginine was apparently absent. The biological activity of the seven microcystins as inhibitors of the catalytic subunit of protein phosphatase-1 (PP-1c) was compared with microcystin-LR and motuporin (a hydrophobic analogue of nodularin). All of the compounds inhibited PP-1c with IC50 values of 0.06-0.4 nM, consistent with their identification as microcystins. These findings further demonstrate the applicability of a sensitive PPase bioassay for the identification of variant microcystins in the natural environment.

Training curricula in surgery, anaesthesia and obstetrics for rural GPs

These three curricula for advanced training practice represent the first significant progress towards the development of specific vocational training for rural general practice. They have been created by rural doctors in consultation with their rural specialist colleagues and with the support of the learned colleges and educationists. Dedicated and enthusiastic project management with a clear understanding of the issues and context of rural general practice was also an essential element for the success of this project. Following implementation and evaluation of the curricula in accredited training posts throughout 1993 and 1994, opportunities will arise to develop further curricula in other medical disciplines and to use the methodology developed for other health fields both in Australia and overseas.

Short report: sedation for upper gastrointestinal endoscopy--diazepam versus midazolam

Intravenously injected midazolam was associated with a greater degree of sedation, as assessed by 24-h retrograde amnesia, than the longer acting benzodiazepine, diazepam. No differences in the frequency of pain on injection or the occurrence of venous sequelae were noted between the two preparations.

The effects of cyclosporine and cyclosporine metabolites in experimental small intestinal transplantation

Cyclosporine metabolites (CM) were compared with cyclosporine for their in vitro and in vivo immunosuppressive, nephrotoxic, and hepatotoxic effects using (A) in vitro mixed lymphocyte induction of monocyte/macrophage procoagulant activity (PCA), an accurate marker of allograft rejection; (B) in vitro toxic effects on renal cells in culture; and (C) a unidirectional rejection model of rat small intestinal transplantation (SIT). CM were composed of OL1, OL17, OL18, and two additional peaks C and H, (peak C: mass = 1235, 15.3% of total CM, peak H: mass = 1205, 6.3% of total CM). In vitro, CM fully suppressed the one-way mixed lymphocyte culture-induced PCA from 52.5 +/- 8.2 mU/10(6) PBM to the basal level 22.3 +/- 6.6 mU/10(6) PBM (P less than 0.01), which was comparable to CsA (21.3 +/- 5.5 mU/10(6) PBM). Lewis rats that had received Lewis-Brown Norway F1 hybrid intestinal allografts when treated with CM, demonstrated near-normal histology with minimal signs of rejection as compared with the fulminant clinical and histological rejection observed in the control (untreated and Cremaphor/NaCl treated) animals. PCA was markedly elevated in the control animals, 278 +/- 172 (untreated) and 160 +/- 98 mU/10(6) PBM (Cremaphor/normal saline treated), whereas CsA-treated allogeneic transplants expressed only basal levels of PCA (14.0 +/- 4 mU/10(6) PBM) (P less than 0.01), associated with normal histology. CM-treated animals expressed PCA levels of 27.0 +/- 10 mU/10(6) PBM, which was significantly different from both control and CsA-treated animals (P less than 0.01). In contrast to CsA-treated animals, CM-treated allogeneic transplants demonstrated no apparent renal or hepatic toxicity, as measured by blood urea nitrogen (25.3 +/- 9.5 vs. 10.0 +/- 5.3 mg/dl), alkaline phosphatase (160.7 +/- 29.3 vs. 100.3 +/- 19.5 U/L), and aspartate transaminase (96.7 +/- 23.7 vs. 61.7 +/- 11.7 U/L) (P less than 0.01). Similarly, in contrast to CsA, CM had minimal or no toxicity in renal epithelial and mesangial cells in culture, as measured by minimal or no inhibition of DNA, RNA, and protein synthesis. These results suggest that CM have potent immunosuppressive properties with no apparent nephrotoxicity and hepatotoxicity in vitro and in vivo.

Characterization of immune responses in different lymphoid compartments during small intestinal allograft rejection

In the present study, we examined the sequential changes of procoagulant activity (PCA) in different host and graft tissue compartments in order to assess its role as an immunologic effector and monitor of the rejection process. An early increase in PCA in the graft mesenteric nodes marks the onset of the host-graft immune interaction prior to any PCA or histologic changes in the other tissue compartments. This was followed by increases in PCA in the peripheral blood and graft intraepithelial compartments coinciding with maximal clinical and histologic signs of rejection. Cyclosporin A fully suppressed alloantigen-induced activation of PCA in the intraepithelial compartment and peripheral blood mononuclear cells, but only partially suppressed PCA in graft mesenteric nodes of the allogeneic transplants. The sequence of PCA changes accurately reflected the clinical and histologic changes during allograft rejection. Thus, PCA measured in peripheral blood mononuclear cells appears to be a sensitive and accurate marker of allograft rejection.

Thrombogenicity of total parenteral nutrition solutions: II. Effect on induction of endothelial cell procoagulant activity

Thrombosis is a common sequela of total parenteral nutrition. We have recently demonstrated in vitro that hypertonic total parenteral nutrition solutions are potent inducers of a tissue factor monocyte procoagulant activity, the initiating cofactor of the extrinsic clotting cascade. We have further studied, in vitro, the effects of the component solutions of total parenteral nutrition on the induction and modulation of endothelial cell procoagulant activity. Cultured porcine aortic endothelial cells were incubated with (a) 200 microliters of dextrose solution (5%, 10%, 20%, 25%, and 50%), (b) 200 microliters of amino acid solution [full strength (N), one-fourth strength, and one-half strength], and (c) 200 microliters of 10% lipid emulsion. Cocultures of lipid emulsion and 20% dextrose, lipid emulsion and full-strength 10% amino acid solution (N-amino acid), and lipid emulsion and bacterial lipopolysaccharide also were studied. Cells were incubated for intervals of 3-108 h, washed and frozen, harvested, and assayed for endothelial cell procoagulant activity. Units of endothelial cell procoagulant activity were derived from a standard thromboplastin curve. Our results show that amino acid and hypertonic dextrose total parenteral nutrition solutions are able to strongly induce endothelial cell procoagulant activity expression in vitro. In contrast, lipid emulsion significantly inhibited the induction of endothelial cell procoagulant activity by 20% dextrose, N-amino acid, and lipopolysaccharide. These results provide further evidence for the role of the cellular pathways of coagulation in total parenteral nutrition-induced thrombosis. Furthermore, the inhibitory properties of lipid emulsion may be of practical advantage in reducing total parenteral nut induced thrombosis.

Thrombogenicity of total parenteral nutrition solutions: I. Effect on induction of monocyte/macrophage procoagulant activity

Although thrombosis is a frequent complication of total parenteral nutrition (TPN), its pathogenesis has received little scientific attention. We have studied, in vitro, the effects of the component solutions of TPN on the induction and modulation of human monocyte procoagulant activity, an initiator of coagulation. Human peripheral blood mononuclear cells were cultured with (a) 200 microliters of dextrose solution (10%, 15%, 20%, 25%, and 50%), (b) 200 microliters of amino acid solution (full, one-half, and one-quarter strength), and (c) 200 microliters of isosmolar 10% lipid emulsion (LE). Cocultures of LE and 20% dextrose, LE and full-strength amino acid solution, and LE and bacterial lipopolysaccharide were also studied. Cells cultured with lipopolysaccharide or medium alone constituted positive and negative controls, respectively. In addition, cocultures of LE and 20% dextrose, LE and full-strength amino acid solution, and LE and lipopolysaccharide were also studied. Cells were incubated for intervals of 12-72 h, washed, frozen, and assayed for monocyte procoagulant activity (MPCA). Milliunits of MPCA were derived from a standard thromboplastin curve. In addition, spontaneous MPCA levels were measured in healthy volunteers (n = 4) and "home" total parenteral nutrition patients (n = 4) before and after a 2-h infusion of 500 ml of LE. Our results show that, in vitro, hypertonic dextrose and full-strength amino acid solutions induce significant levels of MPCA. Induction of MPCA by dextrose was lymphocyte-independent. Although a significant increase in MPCA by full-strength amino acid solution was seen in cultures of isolated monocytes, a lymphocyte requirement was demonstrated for full MPCA. In contrast, LE significantly inhibited the induction of MPCA by 20% dextrose and full-strength amino acid solution. This inhibitory activity was at the monocyte level. Subfractionation of the LE into triglyceride and phospholipid phases showed the inhibitory capacity to reside in the former. In vivo, patients on home total parenteral nutrition expressed higher spontaneous MPCA levels than normal controls. Ten percent lipid emulsion infusion abolished MPCA expression in both groups. These corroborative in vitro and in vivo data suggest a mechanism for the thrombogenicity of total parenteral nutrition solutions and that the inhibitory properties of LE may be of practical advantage in preventing thrombosis.

Sinus arrhythmia in children with atrial septal defect: an analysis of heart rate variability before and after surgical repair

The expression of sinus arrhythmia depends on separation of the systemic and pulmonary venous return to the heart as well as on normal autonomic control mechanisms. Patients with atrial septal defect provide a naturally occurring experiment of communication between the two venous systems. In adults with atrial septal defect sinus arrhythmia is minimal or absent. But children with atrial septal defect retain appreciable sinus arrhythmia, although this is not recognised in published reports. To understand why this is so, continuous electrocardiograms were recorded before and after operation in 10 children (aged 4-16 years, mean 6.3) with atrial septal defects and in 10 normal children (aged 5-7 years, mean 6.1). Mean RR intervals were calculated for periods of one minute, and the standard deviation was used as an index of heart rate variability (that is sinus arrhythmia). Frequency analysis (spectral analysis) was also performed on a continuous beat to beat record of heart rate to describe the frequency components that may reflect autonomic activity. The results confirmed the presence of considerable sinus arrhythmia in children with unoperated atrial septal defect. None the less, the standard deviation of RR intervals in the children with unoperated atrial septal defect was significantly less than that for the normal children, and variation increased after closure of the defect. Power spectral analysis of instantaneous heart rate indicated that the high frequency (0.15-0.45 Hz) vagally mediated component of variability was lower for patients than for controls which may indicate abnormalities of autonomic control of heart rate in these children. The comparative retention of sinus arrhythmia in children with atrial septal defect may relate to the small size of the right atrium or differences in myocardial compliance compared with adults.

Monocyte/macrophage procoagulant activity as a measure of immune responsiveness in Lewis and brown Norway inbred rats. Discordance with lymphocyte proliferative assays

In vitro lymphocyte proliferative assays were performed using Lewis (Lew) and Brown Norway (BN) rats, and compared to induction of monocyte/macrophage procoagulant activity (PCA) in a mixed lymphocyte culture and by endotoxin (LPS) (E. Coli 0111:B4). Splenic mononuclear cells from Lew rats had significantly greater mitogen-induced proliferation to concanavalin A (P = .002) and phytohemagglutinin (P = 0.007). The Lew cells also showed greater allogeneically induced proliferation by BN cells in a one-way MLC in comparison to the reciprocal BN proliferative response (P less than 0.04). PCA induction in peripheral blood mononuclear cells (PBM) by allogeneic stimulation in MLC or total content PCA by LPS did not vary significantly between the 2 strains (P greater than 0.5). Induction of PCA by LPS was rapid, with a moderate rise over basal activity at 3 hr and maximal activity at 6 hr. Two-way allogeneic induction of PCA in PBM from BN and Lew rats resulted in PCA elevation by 3 hr, which became maximal at 18 hr. One-way MLC with Lew or BN cells as responders resulted in moderate increases in PCA by 3-6 hr, with equivalent maximal activities recorded at 18 hr. Viable PCA accounted for 26-32% of total content PCA in both Lew and BN rats. Maximal allogeneic PCA induction by MLC was 14-18% of PCA induced by LPS and required a longer incubation for its expression. Our results indicate that in vitro PCA expression by Lew and BN PBM following allogeneic or endotoxin stimulation shows little interstrain variability in comparison to lymphocyte proliferative responses. Thus PCA appears to more closely reflect the observed in vivo responses of these strains to allogeneic challenge.

Time-space clustering of Vibrio cholerae 01 in Matlab, Bangladesh, 1970-1982

Growing evidence for the existence of an aquatic reservoir of Vibrio cholerae has led some observers to postulate the existence of two distinct modes of disease transmission: primary and secondary. In primary transmission vibrios pass from the aquatic reservoir to humans via edible aquatic flora or fauna, or drinking water. Secondary transmission consists of faecal-oral transmission from person-to-person and may spawn epidemics. Cholera outbreaks are particularly well documented for the Matlab area of Bangladesh, where a field station has been run since 1963, at which patients from a study population of nearly 200,000 are treated for diarrhoeal diseases and monitored in a longitudinal demographic surveillance system. This paper seeks to illuminate the process of secondary transmission by presenting preliminary results of an analysis of the time-space distribution of cholera cases in Matlab for the period 1970-1982. It is argued that the detection of time-space clusters of cases resulting from secondary transmission requires locational data below the level of the village, that is at the level of the bari, or patrilineally-related household group because this is where inter-personal contact is greatest. The mapping of the study area at the bari level is described briefly and it is argued that the proportion of all asymptomatic infections and cases which can be mapped is great enough to enable inferences about transmission processes to be drawn. Results of the analysis of time-space interaction using the Knox method are presented and provide some support for within-bari clustering of cases resulting from secondary transmission.(ABSTRACT TRUNCATED AT 250 WORDS)

Immune responses in small intestinal transplantation in the rat: correlation of histopathology and monocyte procoagulant activity

No predictive serologic marker exists for rejection or graft versus host disease (GVHD) reactions in small intestinal transplantation (SIT). SIT was performed in Lewis (Lew) and Lew X Brown Norway Fl hybrid (LBN) rats in the following combinations: group 1, Lew X Lew; group 2 (isolated rejection), LBN X Lew, and group 3 (isolated GVHD), Lew X LBN. Procoagulant activity (PCA), an index of monocyte immune activation, was measured in the peripheral blood mononuclear cells of graft recipients to assess its value as an immunologic monitor. Histologic findings and PCA were evaluated on days 1, 2, and 3 and every 2 to 3 days after SIT. No pathologic findings of graft or host tissue developed in group 1 (n = 14). Histologic rejection (blunted villi and mononuclear cell infiltration) was seen beginning on day 5 in group 2 (n = 19); early GVHD (loss of nodal and splenic architecture) was first noted on days 5 and 6 in group 3 (n = 17). PCA elevation in SIT was seen to precede histologic evidence of rejection or graft versus host disease in this model and may constitute an important marker for these immunologic events.

Family-centered care for the neurotrauma patient

Nursing management of the family of the neurotrauma patient is a challenging experience. Whether the family is first encountered during their initial days of crisis or following discharge to the home, they require individualized, thoughtful nursing care. Indeed, according to Bond, the pattern of stresses the family encounters changes with time, with one of the most significant points being in the first days after discharge from the hospital when they realize and accept the full extent of the victim's deficits. It is to this end that nursing intervention throughout hospitalization is geared, and it is during this time that we cannot forget that nursing management may still be required. In the case of neurotrauma, the patient and family are not "cured" when they leave the hospital, for many their problems are just beginning. Let us develop mechanisms through which continued professional support can be made available to the families of neurologically impaired patients both during and following hospitalization.

Open intramedullary nailing of the femoral shaft fracture

There is a growing trend to closed intramedullary nailing of femoral shaft fractures that we partially subscribe to. This report, however, concerns open reduction and intramedullary nailing of femoral shaft fractures from 1972-1982. Two groups of fractures are discussed independently--22 pathologic fractures and 88 traumatic fractures. Mortality figures as well as functional and anatomic results are presented. Complications include one superficial infection, two nonunions, and two delayed unions. This study provides us with a baseline measure for comparison with other methods now under consideration and on trial.

Thyroid function and physical activity. A preliminary communication

Images

Studies of the renin-renin substrate reaction in man; kinetic evidence for inhibition by serum

Increasing evidence suggests that the renin-renin substrate reaction is regulated by factors other than the concentrations of enzyme and substrate. Partially purified human renin and renin substrate extracted from the plasma of each of eight human subjects were used to construct substrate-velocity curves comparing the rate of substrate cleavage in the whole serum of each individual with the rate in a corresponding system containing purified autologous substrate, or purified substrate plus a small amount of autologous serum. Linear regression analysis of the double reciprocal plots were used to compare the kinetic constants in paired experiments. Maximal reaction velocity (Vmax) was significantly lower (p greater than .05) when the reaction rate was measured in whole serum, in seven of the eight patients, while Km did not differ significantly, suggesting the presence of noncompetitive inhibition by human serum. The mean Michaelis constant in serum was 449 ng/ml while the average native substrate concentration of the five normal subjects was 629 ng/ml, an excess of less than twofold. The data suggest that plasma renin activity in man depends upon the concentrations of inhibitor and substrate, as well as upon the concentration of renin.