Quantifying arsenic post-depositional mobility in lake sediments impacted by gold ore roasting in sub-arctic Canada using inverse diagenetic modelling.

Lake sediments are widely used as environmental archives to reconstruct past changes in contaminants deposition, provided that they remain immobile after deposition. Arsenic (As) is a redox-sensitive element that may be redistributed in the sediments during early diagenesis, for instance along with iron and manganese, and thus depth profiles of As might not provide a reliable, unaltered record of past deposition. Here, we use inverse diagenetic modelling to calculate fluxes of As across the sediment-water interface and interpret As sedimentary records in eight lakes along a 80 km transect from the Giant and Con mines, Northwest Territories, Canada. The sediment cores were dated using 210Pb methods and analyzed for solid-phase and porewater As, Fe, Mn and organic C concentrations. We reconstructed the history of As deposition by correcting for the varying mobility patterns and calculated contemporary As deposition fluxes. Correction for diagenesis was substantial for three of the eight lakes, suggesting that lakes with lower sedimentation rates, which allows longer residence of As within the reactive zones defined by the model, enhance the influence of diagenesis. Results show that solid phase As peaks coincides with the period of high emissions from past gold ore roasting activities. Results also show that sediments sustained present-day As fluxes to the water column of study lakes within 50 km of the mines, while sediment in study lakes further than 50 km acted as As sinks instead.

Comparative compositional analysis of cassava brown streak disease resistant 4046 cassava and its non-transgenic parental cultivar.

Compositional analysis is an important component of an integrated comparative approach to assessing the food and feed safety of new crops developed using biotechnology. As part of the safety assessment of cassava brown streak disease resistant 4046 cassava, a comprehensive assessment of proximates, minerals, amino acids, fatty acids, vitamins, anti-nutrients, and secondary metabolites was performed on leaf and storage root samples of 4046 cassava and its non-transgenic parental control, TME 204, collected from confined field trials in Kenya and Uganda over two successive cropping cycles. Among the 100 compositional components that were assessed in samples of 4046 and control TME 204 cassava roots (47 components) and leaves (53 components), there were no nutritionally relevant differences noted. Although there were statistically significant differences between the transgenic and control samples for some parameters, in most cases the magnitudes of these differences were small ( < 20%), and in every case where comparative literature data were available, the mean values for 4046 and control cassava samples were within the range of normal variation reported for the compositional component in question. Overall, no consistent patterns emerged to suggest that biologically meaningful adverse changes in the composition or nutritive value of the leaves or storage roots occurred as an unintended or unexpected consequence of the genetic modification resulting in 4046 cassava. The data presented here provide convincing evidence of the safety of 4046 cassava with respect to its biochemical composition for food and feed, and it could be considered as safe as its non-transgenic control.

Recombinant human acidic fibroblast growth factor and fibrin carrier regenerates bone.

Bone regeneration promoted by acidic recombinant human fibroblast growth factor (rhFGF-1), rabbit demineralized bone matrix (rDBM), and a fibrin (f) delivery system was measured in critical-sized defects in rabbits' radii. A unilateral segmental defect 20 mm in length was prepared in radii of 48 skeletally mature New Zealand White rabbits divided equally between 4- and 8-week cohorts. The temporal cohorts were divided equally among four treatment groups: rDBM, rDBM/f, rDBM/rhFGF-1/f, and rhFGF-1/f. Data for the fifth group, untreated critical-sized defects, were exploited from previous published reports from this laboratory. In response to experimental treatments, radiomorphometric and histomorphometric methods were used to derive quantitative outcome data that were tested by analysis of variance and post hoc multiple comparison tests (significance p

Early recovery after endoscopic vs. short-incision open carpal tunnel release.

Endoscopic carpal tunnel release has been claimed to offer improvement in recovery time and postoperative discomfort over open carpal tunnel release. Short-incision open carpal tunnel release has been claimed to offer recoveries comparable with endoscopic techniques. Patients receiving carpal tunnel surgery were randomized to short-incision open release or single-portal endoscopic release. Preoperative and postoperative evaluation included grip and pinch strength measurements and patient completion of a questionnaire regarding symptoms and function. Thirty-six operated hands completed evaluation, including 22 endoscopic and 14 open releases. Early grip and pinch strength after endoscopic carpal tunnel release were improved significantly over short-incision open release (p < 0.05). Subjective evaluation indicated a trend toward improved symptoms and function with endoscopic over short-incision open carpal tunnel release. Endoscopic carpal tunnel release provides faster recovery of strength than short-incision open carpal tunnel release and improves early postoperative comfort and function to a small degree.

Orbital floor repair with titanium mesh screen.

BACKGROUND AND OBJECTIVES: Surgical repair of the acutely fractured orbit strives to restore appearance, preserve ocular and orbital function, and avoid enophthalmos or hypoglobus. Repair is achieved with autologous bone graft, synthetic substitutes, or both. The purpose of this article is to present an alternative procedure--use of implants, cut from a titanium mesh screen, without bone graft. METHOD AND MATERIALS: A total of 51 orbital floor fractures in 43 patients were repaired with titanium mesh screen implants. In three patients with bilateral orbital floor fractures repaired with titanium mesh, intraoperative symmetry was improved with bone graft added to the mesh on one side. RESULTS AND/OR CONCLUSIONS: Follow-up was available for 42 orbits in 35 patients and averaged 9 months. The transconjunctival approach with lateral canthotomy yielded better results than the subciliary approach, which often caused transient scleral show or ectropion. One patient underwent surgery for ectropion following a subciliary approach, and one patient developed a 4-mm enophthalmos. Routine bone grafting is unnecessary, even in large floor defects. Titanium mesh implants are a simple and reliable option for orbital floor repair.

Granular cell tumor of the biliary system.

Granular cell tumors (GCT) are rare benign neoplasms of Schwann cell origin which have been found in virtually every location in the body. Their location in the biliary system is unusual, and typically occurs in black females during the fourth decade of life. Forty-eight cases have been reported since 1952. We present two patients treated for obstructive jaundice caused by GCT of the extrahepatic biliary tree. The literature on biliary GCT is reviewed and their management is outlined. Local excision with Roux-y-hepaticojejunostomy was performed in one patient with GCT obstructing the common bile duct at the level of the cystic duct. Pancreaticoduodenectomy was performed on one patient for GCT of the common bile duct involving the ampulla and adjacent pancreas. GCT of the extrahepatic biliary system are rare but should be considered in black females who present with obstructive jaundice in the fourth decade of life. Local excision with cholecystectomy and reconstruction of the biliary remnant is indicated. Primary biliary anastomosis is desired but choledochojejunostomy or hepaticojejunostomy may be necessary. Rarely, pancreaticoduodenectomy may be indicated in GCT of the distal common bile duct.

Fatal cerebral gunshot wounds: factors influencing organ donation.

Patients with clinical brain death following head injury are important potential cadaveric organ donors. We analyzed our series of cranial gunshot wounds with particular attention to the frequency and patterns of organ donation after fatal injuries. Sixty-six patients with gunshot wounds to the head, including 59 with intracranial involvement (43 male, average age 26 years) were seen during a 4-year period. Injuries were limited to the head in 50 of 59 patients. Overall mortality was 66 per cent. Predictors of mortality included Glasgow Coma Scale (GCS) of six or less (93%), self-inflicted gunshot wounds (75%), and computed tomography (CT) findings of bihemispheric injury (87%) or ventricular injury (82%). Of the 39 patients who died, 28 met standard criteria for brain death, and nine of these went on to organ procurement. Thirteen families refused donation, and six patients were not harvested for reasons including old age, pregnancy, suspicion of AIDS, coroner refusal, and failure to pursue consent. Principles essential to maximal organ retrieval include: 1) Recognition that patients suffering cerebral gunshot wounds represent potential organ donors and that certain factors are predictive of mortality; 2) Critical care/trauma team approach with standardized management and timely declaration of brain death; 3) Early search for family members and prompt notification of organ procurement agencies; 4) Sensitivity to cultural issues influencing donation; and 5) Programs to increase public awareness of organ donation.

Laparoscopic excision of a mesenteric cyst.

Benign abdominal cystic tumors are rare. They include retroperitoneal, mesenteric, and omental cysts. Most of these lesions present with vague abdominal pain and nausea. Less commonly they will present with bowel obstruction due to external compression. The diagnosis of these tumors is by abdominal ultrasound or computed tomography. Surgical enucleation is the treatment of choice. Laparoscopic surgical techniques are replacing or complimenting open abdominal surgical procedures. As the indications for these techniques increase, newer applications will arise. Presented here is a case of laparoscopic excision of a mesenteric cyst.

Continuous intra-arterial oxygen monitoring: accuracy and reliability in the surgical intensive care unit.

The accuracy and reliability of an invasive intra-arterial oxygen sensor catheter was evaluated in 20 critically ill surgical intensive care unit (SICU) patients. All patients required continuous arterial blood pressure monitoring, at least 72 hours of ventilator support, and intermittent arterial blood gas sampling for clinical management. The intra-arterial sensor provided continuous PO2 (PsO2) values on a bedside electronic monitor. PsO2 values were sampled every 60 seconds and automatically stored on a bedside personal computer. Arterial blood gas (ABG) PaO2 values were collected and matched by collection time with corresponding PsO2 values. During 1,238 hours of continuous intra-arterial monitoring, 74,280 PsO2 values and 246 ABG PaO2 values were collected. Of the 246 PaO2 results, 175 (71.3%) had a matching PsO2. Regression of matched PsO2 and PaO2 values yielded a correlation coefficient of 0.58 and standard error of the estimate (SEE) of 33.1 (P < 0.0005). Even though matched PsO2 and PaO2 measurements demonstrated a linear relationship, only 34 per cent of the variation in PsO2 could be attributed to changes in PaO2. Technical sensor or instrument problems affected PsO2 monitoring in 17 of 20 patients and 28 of the 33 sensors tested. The authors conclude that continuous intra-arterial monitoring of PsO2 is a novel idea, but technical issues limit its use in acutely ill, conscious SICU patients.

Vascular complications of the intra-aortic balloon pump.

The lower extremity complications of 100 consecutive patients who required the placement of an intra-aortic balloon pump (IABP) during a 3-year period were studied. Indications for the IABP included hypotension during cardiac catheterization (33%) or coronary angioplasty (13%), hemodynamic instability after open heart surgery (35%), unstable angina (5%), and cardiac arrest (14%). The incidence of IABP morbidity was 29%. Complications included ischemia (25%), bleeding (2%), lymph fistula (1%), and femoral neuropathy (1%). Twenty patients required 1 or more surgical interventions for lower extremity vascular complications. The majority of patients who underwent operation (70%) had significant pre-existing arterial occlusive disease. Local femoral artery reconstruction or repair was performed in 18 patients. Two patients had adjunctive bypasses. Continued IABP support was required in four patients after treatment of complications. One patient (1%) had an above-knee amputation. Limb ischemia was treated nonoperatively by removal of the IABP in five patients. Color-flow duplex scans were useful in distinguishing hematomas from pseudoaneurysms as well as for assessing femoral artery flow. We conclude that: (1) limb ischemia remains the primary complication of the IABP; (2) pre-insertion documentation of the severity of existing peripheral arterial disease by noninvasive studies may aid in the management of subsequent acute limb ischemia; (3) femoral artery thrombectomy or endarterectomy is usually sufficient for revascularization; and (4) noninvasive color flow studies are an important diagnostic tool in the nonoperative management of limb complications.

Resistance to tomato spotted wilt virus infection in transgenic tobacco expressing the viral nucleocapsid gene.

A recombinant plasmid containing the entire tomato spotted with virus (TSWV) nucleocapsid gene, with the exception of nucleotide encoding three N-terminal amino acids, was isolated by screening a complementary DNA library, prepared against random primed viral RNA, using a specific monoclonal antibody. The insert contained in plasmid pTSW1 was repaired and amplified by polymerase chain reaction, and the complete nucleocapsid protein gene was introduced into Nicotiana tabacum 'Samsun' by leaf disk transformation using Agrobacterium tumefaciens. Transgenic plants expressing the viral nucleocapsid protein were resistant to subsequent infection following mechanical inoculation with TSWV as indicated by a lack of systemic symptoms and little or no systemic accumulation of virus as determined by double antibody sandwich enzyme-liked immunosorbent assay. These results further extend the applicability of coat protein-mediated resistance, as previously demonstrated for a number of simple plant viruses composed of a positive-sense RNA genome encapsidated with a single species of coat protein, to a membrane-encapsidated, multi-component, negative-sense RNA virus.

Transgenic Nicotiana debneyii expressing viral coat protein are resistant to potato virus S infection.

The coat protein gene from potato virus S (PVS) was introduced into Nicotiana debneyii by leaf disc transformation using Agrobacterium tumefaciens. Transgenic plants expressing the viral coat protein were highly resistant to subsequent infection by the ME strain of PVS as indicated by an absence of symptom development and a lack of accumulation of virus in both the inoculated and upper leaves. As in reported experiments with plants expressing potato virus X coat protein, plants expressing PVS coat protein were also protected from inoculation with PVS RNA. These results provide further evidence that coat protein-mediated protection for these two groups of viruses, which share similar genome organizations, may involve inhibition of some early event in infection other than or in addition to virus uncoating.

Organization and interviral homologies of the 3'-terminal portion of potato virus S RNA.

The sequence of 3553 nucleotides corresponding to the 3'-terminal region of potato virus S (PVS) has been determined from cloned cDNA. The sequence obtained contains six open reading frames (ORFs) encoding proteins of Mr 10,734, Mr 32,515, Mr 7,222, Mr 11,802, Mr 25,092 and at least Mr 41,052. The sequence of the 33K ORF has been confirmed to be that of the viral coat protein gene. The nucleotide sequence of this ORF was obtained from plasmids which were isolated by colony hybridization with a specific monoclonal antibody to PVS, and the expression of coat protein fusion products was verified by Western blots of bacterial cell lystates. The deduced amino acid sequence of a 70 amino acid portion from the central region of the PVS coat protein was 59% identical to the analogous region of potato virus X. In addition, the 7K, 12K and 25K ORFs displayed significant sequence homology with the similarly sized ORFs from a number of potexviruses. The partial 41K ORF product was homologous with the C-terminal portion of the viral replicase proteins of potato virus X and white clover mosaic virus.

Duration discrimination of speech and tonal complex stimuli by normally hearing and hearing-impaired listeners.

The ability to discriminate changes in the length of vowels and tonal complexes (filled intervals) and in the duration of closure in stop consonants and gaps in tonal complexes (unfilled intervals) was studied in three normally hearing and seven severely hearing-impaired listeners. The speech stimuli consisted of the vowels (i, I, u, U, a, A) and the consonants (p, t, k), and the tonal complexes consisted of digitally generated sinusoids at 0.5, 1, and 2 kHz. The signals were presented at conversational levels for each listener group, and a 3IFC adaptive procedure was used to estimate difference limens (DLs). The DLs for speech were similar to those for tonal complex stimuli in both the filled and unfilled conditions. Both normally and impaired-hearing listeners demonstrated greater acuity for changes in the duration of filled than unfilled intervals. Mean thresholds for filled intervals obtained from normally hearing listeners were smaller than those obtained from hearing-impaired listeners. For unfilled intervals, however, the difference between listener groups was not significant. A few hearing-impaired listeners demonstrated temporal acuity comparable to that of normally hearing listeners for several listening conditions. Implications of these results are discussed with regard to speech perception in normally and impaired-hearing individuals.

Determination of affinity constants and the number of binding sites of monoclonal antibodies specific for southern bean mosaic virus.

Values of the equilibrium dissociation constant and the number of attachment sites for the binding of radiolabeled F(AB) fragments prepared from four monoclonal antibodies to southern bean mosaic virus have been determined. Monoclonal antibodies B6 and B10 produced against the bean type strain of southern bean mosaic virus (SBMV-B) and 1C4 and 1D6 produced against the cowpea type strain (SBMV-C) were more reactive with the untreated virus than with EDTA-swollen particles. B6 and B10 reacted with 180 and 90 sites, respectively, on the SBMV-B particle and were not reactive with SBMV-C. Antibody 1D6 reacted with 180 sites on both SBMV-B and SBMV-C, whereas 1C4 bound to 180 sites on SBMV-C and 60 sites on SBMV-B. The equilibrium dissociation constants for B10, 1C4, and 1D6 were similar but antibody B6 bound with an 8- to 10-fold lower affinity. Solid phase competitive antibody inhibition analysis showed that 1C4 and 1D6 were mutually inhibitory and that these antibodies also inhibited the binding of B6 and B10. Antibody B6 partially inhibited the binding of 1D6 but did not affect 1C4 or B10 binding. No inhibition of B6, 1C4, or 1D6 binding was observed when B10 was the competing antibody. Possible sites of reaction of these monoclonal antibodies on the SBMV particle are discussed.

Monoclonal antibodies as structural probes of southern bean mosaic virus.

The reactivity of six monoclonal antibodies with native southern bean mosaic virus particles, swollen virus, swollen virus contracted by divalent cations or by pH adjustment to 5.0, and virus coat protein at pH 7.5 and 5.0 were assessed by antigen inhibition enzyme-linked immunosorbent assays. Clones B4, B7, and B11 did not react with native virus but were inhibited by low levels of all nonnative virus antigens. B6 had a high reactivity only with the native virus. B5 and B10 reacted equally with native virus and swollen virus contracted by Ca2+ or by pH adjustment, but reacted only weakly with swollen virus or swollen virus contracted by Mg2+. B5 reacted with viral protein at pH 5.0 and weakly with coat protein at pH 7.5, whereas B10 did not react with protein at pH 7.5 and had only limited reactivity with viral protein at pH 5.0. The reactivity of B5 and B10 with swollen virus increased as the pH was gradually decreased between 7.3 and 6.5. Similarly, their reactivity with swollen-contracted virus decreased as the pH was increased within the same range. Reactivity versus pH plots of these two transition forms showed hysteresis with B10 but did not with B5.

Subacute sclerosing panencephalitis (SSPE) in southern Africa. Recent additions to the SSPE Registry.

Subacute sclerosing panencephalitis can no longer be regarded as a rare disease in all parts of southern Africa. Information derived from a third postal survey added to that from our own experience in Cape Town has brought to light 116 cases; 61 of the patients came from the Cape Province, 40 from the Transvaal and the remaining 15 from the other regions. This unequal distribution and the high prevalence in the Coloured community are important factors in any attempt to understand the epidemiology and the pathogenesis of this serious complication of measles.

Register of cases of subacute sclerosing panencephalitis (SSPE) in Southern Africa.

An analysis of cases of subacute sclerosing panencephalitis (SSPE) in Southern Africa to the end of 1976 is presented. In the 2 years since the last report in 1975, 15 new cases have been added to the register. Seven patients from the Cape Province were investigated in Groote Schuur and Red Cross War Memorial Children's Hospitals in Cape Town and a recent postal survey revealed 6 cases in the Transvaal and 1 each from South West Africa and Rhodesia. This analysis indicates that the high incidence and temporal clustering of cases in the Cape Province is continuing, and that the relatively constant annual number of cases in the Transvaal and the apparent absence of the disease in Natal and the Orange Free State are being maintained.