Detection of wood cell wall porosity using small carbohydrate molecules and confocal fluorescence microscopy.

A novel approach to nanoscale detection of cell wall porosity using confocal fluorescence microscopy is described. Infiltration of cell walls with a range of nitrophenyl-substituted carbohydrates of different molecular weights was assessed by measuring changes in the intensity of lignin fluorescence, in response to the quenching effect of the 4-nitrophenyl group. The following carbohydrates were used in order of increasing molecular weight; 4-nitrophenyl ß-D-glucopyrano-side (monosaccharide), 4-nitrophenyl ß-D-lactopyranoside (disaccharide), 2-chloro-4-nitrophenyl ß-D-maltotrioside (trisaccharide), and 4-nitrophenyl α-D-maltopentaoside (pentasaccharide). This technique was used to compare cell wall porosity in wood which had been dewatered to 40% moisture content using supercritical CO2, where cell walls remain fully hydrated, with kiln dried wood equilibrated to 12% moisture content. Infiltration of cell walls as measured by fluorescence quenching, was found to decrease with increasing molecular weight, with the pentasaccharide being significantly excluded compared to the monosaccharide. Porosity experiments were performed on blocks and sections to assess differences in cell wall accessibility. Dewatered and kiln dried wood infiltrated as blocks showed similar results, but greater infiltration was achieved by using sections, indicating that not all pores were easily accessible by infiltration from the lumen surface. In wood blocks infiltrated with 4-nitrophenyl α-D-maltopentaoside, quenching of the secondary wall was quite variable, especially in kiln dried wood, indicating limited connectivity of pores accessible from the lumen surface.

Fluorescence lifetime imaging of lignin autofluorescence in normal and compression wood.

Wood cell walls fluoresce as a result of UV and visible light excitation due to the presence of lignin. Fluorescence spectroscopy has revealed characteristic spectral differences in various wood types, notably normal and compression wood. In order to extend this method of characterising cell walls we examined the fluorescence lifetime of wood cell walls using TCSPC (Time-Correlated Single Photon Counting) as a method of potentially detecting differences in lignin composition and measuring the molecular environment within cell walls. The fluorescence decay curves of both normal and compression wood from pine contain three exponential decay components with a mean lifetime of τm = 473 ps in normal wood and 418 ps in compression wood. Lifetimes are spatially resolved to different cell wall layers or cell types where individual lifetimes are shown to have a log-normal distribution. The differences in fluorescence lifetime observed in pine compression wood compared to normal wood, are associated with known differences in cell wall composition such as increased p-hydroxyphenyl content in lignin as well as novel deposition of ß(1,4)-Galactan. Our results indicate increased deposition of lignin fluorophores with shorter lifetimes in the outer secondary wall of compression wood. We have demonstrated the usefulness of fluorescence lifetime imaging for characterising wood cell walls, offering some advantages over conventional fluorescence imaging/spectroscopy. For example, we have measured significant changes in fluorescence lifetime resulting from changes to lignin composition as a result of compression wood formation that complement similar changes in fluorescence intensity.

Evaluation of pre- and posttransplant donor-specific transfusion/cyclosporine A in non-HLA identical living donor kidney transplant recipients. Cooperative Clinical Trials in Transplantation Research Group.

BACKGROUND: The beneficial effects of donor specific transfusion (DST) have become controversial in the cyclosporine era. This study was performed to evaluate the potential benefits of a new protocol for administering DSTs in the perioperative period. METHODS: Non-HLA identical living donor kidney transplant recipients were randomized prospectively to control or to receive a DST 24 hr before transplant and 7-10 days posttransplant. All patients received similar immunosuppression according to protocol. RESULTS: The protocol had 212 evaluable patients (115 transfused and 97 control). There were no differences in 1- and 2-year graft and patient survival, causes of graft failure, incidence and types of infection, repeat hospitalization, or the ability to withdraw steroids. Immunological hyporesponsiveness (by mixed lymphocyte culture) occurred more frequently in transfused patients (18%) than controls (3%) (P = 0.04). Blood stored for > or =3 days was associated with fewer early rejections than blood stored < or =2 days. Overall, class II antigen mismatches were associated with more rejection episodes than class I antigen mismatches. However, transfused patients, but not control patients, with more class I antigen mismatches were more likely to have rejections. CONCLUSIONS: Administration of DSTs by the method described had no practical influence on patient or graft survival for up to 2 years. However, donor-specific hyporesponsiveness was more common in transfused patients (18 vs. 3%). Longer follow-up will be needed to determine whether DST will be associated with long-term benefit.

Relationship between underlying renal disease and renal transplantation outcome.

The purpose of this study is to better characterize graft and patient survival posttransplantation by examining survival according to underlying renal disease for all first-time renal allograft recipients in the United Network for Organ Sharing (UNOS) registry. From 1987 through 1996, the UNOS registry collected data on 23,838 living and 67,183 cadaveric renal transplantations. This investigation included all patients undergoing their first renal transplantation for whom the underlying cause of renal failure could be identified and categorized. Gross 1- and 3-year patient and graft survival according to underlying renal disease are included. In addition, a Cox proportional hazards model was created to analyze the effect of underlying disease on graft and patient survival after adjusting for comorbid conditions, demographics, and type of renal transplant (living versus cadaveric). The association between underlying disease and graft and patient survival is shown. Amyloidosis, sickle cell anemia, scleroderma, and radiation nephritis are associated with poor graft and patient survival. The risk ratio for patient mortality was more than twice that for immunoglobulin A nephropathy for a number of conditions, including analgesic nephropathy, amyloidosis, and both forms of diabetes mellitus.

Risk factors for mortality in infants and young children on dialysis.

The factors associated with a greater mortality risk in infants and young children undergoing dialysis have not been clearly determined. We report the results of a North American Pediatric Renal Transplant Cooperative Study designed to assess risk factors in patients aged younger than 6 years at initiation of dialysis therapy. Sixty-four nonsurvivors were matched with 110 survivors for age at dialysis initiation, primary renal disease, and year of entry onto the database. Questionnaires on 137 patients (51 nonsurvivors, 86 survivors) were completed by participating centers. Seventy-five percent (103 of 137 patients) of the patients were aged younger than 2 years at dialysis initiation; 42% (58 of 137 patients) had renal aplasia, dysplasia, and/or hypoplasia or obstructive uropathy; 62% were boys; and 62% were white. One-year patient survival rates were 83% in infants beginning dialysis at younger than 3 months of age, 89% in 3- to 23-month-olds, and 95% in 2- to 5-year-olds (P = 0.001). Comorbid nonrenal disease occurred in 37 of 51 nonsurvivors (74%) versus 46 of 84 survivors (55%; P = 0.027). Nonsurvivors had pulmonary disease and/or hypoplasia more often (14 of 37 nonsurvivors; 37.8% versus 8 of 46 survivors; 17.4%; P = 0.04). Oliguria or anuria was present in 23 of 33 nonsurvivors (70%) aged younger than 2 years versus 26 of 64 survivors (41%; P = 0.007). Infection accounted for 15 of 51 deaths (29.4%). In summary, these results suggest that age at dialysis initiation; presence of nonrenal disease, particularly pulmonary disease and/or hypoplasia; and oliguria or anuria in children aged younger than 2 years are identifiable as risk factors for mortality in these young patients.

Experimental pancreatitis: Effect of plasma and dextran on pancreatic blood flow.

In spite of extensive investigations, many aspects of the hemodynamic changes occurring in acute pancreatitis are understood poorly. A dog model was established in which continuous measurements of pancreatic arterial blood flow, cardiac output, and mean arterial blood pressure were made using electromagnetic flow probes and a pressure transducer, respectively. Pancreatitis was induced and the animals were monitored for 3 hours. In addition, control animals (group I) without pancreatitis also were done. All animals 50 ml of saline in the first hours. Three methods of therapy then were instituted in the dogs with pancreatitis and their effects were recorded. group I 6 dogs control animals no pancreatitis saline 50 ml/hr group II 10 dogs saline 50 ml/hr group III 6 dogs plasma 15 ml/kg over 45 min then saline 50 ml/hr group IV 10 dogs saline 50 ml and 1.5 ml/kg of dextran 40/hr These results confirm the observations made previously using a transillumination technique--that the pancreatic circulation rapidly reduces in acute pancreatitis. Administration of plasma produced a significant (P less than 0.05) but transient increase in the cardiac output and pancreatic blood flow; however, the blood pressure remained low. Dextran 40 minimally increased cardiac output, but it significantly improved the blood pressure and maintained the pancreatic blood flow. Low-dose, low-molecular weight dextran 40 appears to help to maintain pancreatic blood flow in acute pancreatitis. The possible mechanisms concerning the made of action of dextran 40 will be discussed.

Management of a mediastinal cyst causing hyperparathyroidism and tracheal obstruction.

A 78-year-old man with a history of parathyroidectomy presented with hyperparathyroidism and tracheal obstruction. After excision of the mediastinal parathyroid cyst, his symptoms were completely relieved. The diagnosis, investigations, and management are discussed.

Lignification and lignin topochemistry - an ultrastructural view.

This review discuses the ultrastructural aspects of cell wall lignification and lignin topochemistry. Lignification results from the enzyme mediated polymerization of monolignols initiated by unknown factors (initiation sites) located at the corners of cells and in the middle lamella. Lignification results in the filling of pores within the carbohydrate matrix following a sequence from the outer regions of the wall towards the lumen. The amount and chemical characteristics of lignin vary across the cell wall, with the presence of reaction wood, and among cell types.

Surgeon-controlled ultrasound-guided core biopsies in the breast--a prospective study and a new use for surgeons in the clinic.

AIMS: This study was to assess the accuracy of a surgeon performing ultrasound-guided core biopsies of the breast. METHODS: A prospective audit was carried out of 555 patients who underwent an ultrasound-guided core biopsy for a discrete solid mass [under 30 mm maximum diameter] by a single surgeon. The surgeon controlled the core biopsy needle and an ultrasonographer or radiologist provided the imaging with ultrasound. RESULTS: The accuracy of the surgeon in sampling the lesions [n = 555 core biopsies] was independent of the size of the lesion. This saved 272 patients having unnecessary surgery for a benign lesion. CONCLUSION: The practical involvement by the surgeon in breast ultrasound and performing core biopsies has reduced pressure on the breast radiologists, reduced the number of diagnostic surgical open biopsies and made the clinic more interesting for the surgeon. With increased surgical confidence in breast ultrasound, most small and impalpable cancers have pre-operative skin marking rather than X-ray wire localization prior to undergoing wide local excision. Trainee breast surgeons should be encouraged to learn breast ultrasound and core biopsies.

Acute pancreatitis - ischaemia or hyperaemia?

There is no accepted specific treatment for acute pancreatitis in man in spite of extensive investigations. Evidence is presented based on histology, vascular and blood flow studies to support the hypothesis that acute pancreatitis is unlike most inflammatory conditions since a rapid and severe ischaemia develops in the pancreas. In dogs for example there is an instant and maintained reduction in pancreatic blood flow reducing by 72% at 3 hours. Various treatments have been advocated in acute pancreatitis. Based upon the effect of dextran 40 in improving pancreatic blood flow and percentage cardiac output, it would appear to be a treatment of choice in acute pancreatitis.

The role of the intensive care unit in a district hospital.

The evolution of an intensive care facility in a District General Hospital is recorded. Optimum use of the Unit was achieved by accepting both critically ill and high dependency care patients. This has been of benefit to both the staff and patients and may be reflected in the falling mortality of the critically ill surgical patient. High dependency care patients now only stay 1.3 days and there has been no mortality. In view of the ageing population and the cost of such units, this dual role in the District General Hospital Intensive Care Unit appears justified.

The Biethium bridge--an advance in stoma care.

The majority of currently available colostomy bridges lie on the skin surface. Until their removal around the seventh postoperative day, they frequently prevent the formation of a complete seal between the appliance and the skin, resulting in faecal leakage. This is distressing to the new stoma patient. In contrast, the Biethium bridge is inserted subcutaneously producing a small, flush stoma to which the colostomy bag can easily be applied and therefore faecal leakage is no longer a problem. Our experience with 35 patients is described.

A cause of misleading serum amylase concentrations in acute pancreatitis.

The operative discovery of acute pancreatitis associated with gross hyperlipidaemia but a normal or high elevated serum amylase concentration has been described. We report a case of acute pancreatitis in which serial dilutions of serum resulted in a 338% rise in the serum amylase concentrations. The importance of appreciating this effect of hyperlipidaemia on the serum level measurements in patients with acute pancreatitis is re-emphasised.

Serial serum amylase levels in patients with pancreatic pseudocysts.

The incidence of hyperamylasaemia in serial serum amylase levels from patients with pancreatic pseudocysts is not well documented in the literature. Accordingly serial amylase levels were estimated in 5 patients with proven pancreatic pseudocysts. The majority of the values were normal or only minimally elevated. In contrast the amylase thermolability was persistently elevated and appeared to be a more sensitive measurement than serum amylase activity for indicating the presence of pancreatic pseudocysts.

Effect of venous (gut) CO2 loading on intrapulmonary gas fractions and ventilation in the tegu lizard.

Studies were conducted to determine regional pulmonary gas concentrations in the tegu lizard lung. Additionally, changes in pulmonary gas concentrations and ventilatory patterns caused by elevating venous levels of CO2 by gut infusion were measured. It was found that significant stratification of lung gases was present in the tegu and that dynamic fluctuations of CO2 concentration varied throughout the length of the lung. Mean FCO2 was greater and FO2 less in the posterior regions of the lung. In the posterior regions gas concentrations remained nearly constant, whereas in the anterior regions large swings were observed with each breath. In the most anterior sections of the lung near the bronchi, CO2 and O2 concentrations approached atmospheric levels during inspiration and posterior lung levels during expiration. During gut loading of CO2, the rate of rise of CO2 during the breathing pause increased. The mean level of CO2 also increased. Breathing rate and tidal volume increased to produce a doubling of VE. These results indicate that the method of introduction of CO2 into the tegu respiratory system determines the ventilatory response. If the CO2 is introduced into the venous blood a dramatic increase in ventilation is observed. If the CO2 is introduced into the inspired air a significant decrease in ventilation is produced. The changes in pulmonary CO2 environment caused by inspiratory CO2 loading are different from those caused by venous CO2 loading. We hypothesize that the differences in pulmonary CO2 environment caused by either inspiratory CO2 loading or fluctuations in venous CO2 concentration act differently on the IPC. The differing response of the IPC to the two methods of CO2 loading is the cause of the opposite ventilatory response seen during either venous or inspiratory loading.

The effect of Trasylol and vasopressin on experimental pancreatitis.

A dog model was established to measure the hemodynamic changes occurring during experimental pancreatitis. The effect of treatment with Trasylol and vasopressin, beginning 60 minutes after induction of pancreatitis was assessed by their effect on the pancreatic hemodynamics. The pancreatic arterial blood flow fell by 72 per cent in the dogs with induced pancreatitis and treated only with saline solution. In contrast, the pancreatic blood flow fell by 58 per cent in the Trasylol group and 80 per cent in the vasopressin group. In addition, vasopressin had a detrimental effect on the cardiac output. Neither treatment altered the changes noted in the systemic blood pressure. Trasylol had a slight beneficial effect on experimental pancreatitis when assessed by its effect on the pancreatic hemodynamics. In contrast, vasopressin had a detrimental effect on the pancreatic hemodynamics.

Experimental acute pancreatitis: the changes in pancreatic oxygen consumption and the effect of Dextran 40.

A canine model was devised to measure the oxygen consumption of the pancreas in experimentally induced pancreatitis. Over the 120 minute investigation period the oxygen consumption fell by 63% in the presence of a diminishing pancreatic blood flow and constant arteriovenous percentage saturation across the pancreas. Dextran 40 has been previously shown to maintain the pancreatic circulation. Accordingly a second group of dogs was treated with Dextran 40 (1.5 ml/kg) 60 minutes after induction of the pancreatitis. This produced a significant increase in the pancreatic oxygen consumption and widening of the arteriovenous difference. Dextran 40 appears to reverse the hypoxia of the pancreas noted in acute experimental pancreatitis.

A clinicopathological review of 68 carcinomas of the gallbladder.

A clinical and pathological review of 68 patients with a primary carcinoma of the gallbladder was undertaken. A prolonged preceding history of biliary disease was noted. Preoperative radiological and biochemical investigations were not helpful, but an isolated elevation in serum alkaline phosphatase level in the absence of any biliary obstruction or hepatic dysfunction was noticed in some patients. The significance of stones in relation to pathogenesis is discussed. A more radical surgical approach involving a partial hepatectomy appears to be the only possible treatement in veiw of the mode of spread of this tumour and the bad overall prognosis.

Fungal peritonitis in children receiving peritoneal dialysis: a report of the NAPRTCS.

BACKGROUND: The rarity of fungal peritonitis (FP) in children receiving chronic peritoneal dialysis (PD) has limited the amount of information available regarding the risk factors and management associated with this infection. METHODS: We reviewed all cases of FP occurring in patients entered into the dialysis registry of the NAPRTCS between January 1992 and May 1996 in an attempt to identify risk factors for infection, treatment strategies, and patient outcome data. A total of 1592 patients who were less than 21 years of age were enrolled in the dialysis registry and received maintenance PD during the period of observation. RESULTS: Of the total 1729 episodes of peritonitis in these patients occurring over 1732 patient-years of follow-up, FP accounted for 51 (2.9%) of the episodes. The patients on PD who developed FP were similar to those who did not develop FP with regard to race, gender, dialysis modality, and dialysis access characteristics. The overall peritonitis rate in patients who developed FP was 2.2 episodes per patient-year compared with 0.96 episodes per patient-year in the patients who did not develop this infection (P < 0.0001). In 25 (49%) cases, the FP was the patient's initial episode of peritonitis. Whereas recent antibiotic usage was present in 23 (56%) of 41 patients with FP, there was no statistically significant relationship (P = 0.26) noted between the presence of a gastrostomy and the development of FP. Candida species caused 33 of 42 (78.6%) FP episodes. Therapy consisted of PD catheter removal and Amphotericin B in the majority of patients. Six months after diagnosis, 27 patients remained on PD, twelve patients were receiving hemodialysis, and only three patients had died, in each case for reasons unrelated to their FP episode. CONCLUSION: FP is an infrequent cause of peritonitis in children receiving chronic PD. The presence of a gastrostomy does not appear to predispose patients to the development of this infection, and successful therapy most often consists of a combination of antifungal medication and dialysis catheter removal. The outcome of FP in children appears to be more favorable than in the adult dialysis population.

T lymphocyte heterogeneity in the rat. III. Autoreactive T cells are activated by B cells.

Evidence has been presented to show that CD4+ autoreactive T cell lines (ATs)2 in the rat require periodic stimulation with syngeneic spleen cells for in vitro proliferation. This proliferation can be blocked by treatment of the stimulator (spleen) cells with mAb to Ia antigens. Although ATs are Ia+ and can activate the allogeneic MLR, they fail to be autostimulatory. Fractionation of the spleen cells revealed that ATs can be stimulated with B cells and not by macrophages, although the latter were efficient in several accessory cell functions, including antigen presentation, lectin-dependent T cell activation and allogenic MLR response. Moreover, B cells proliferated and differentiated in response to AT cells. These data are compatible with a model in which ATs respond to hitherto undetermined B cell membrane antigen(s) in association with MHC class II antigens. These results may have important implications in understanding autoimmune responses.