Allograft Pancreatectomy: Indications and Outcomes.

This study evaluated the indications, surgical techniques, and outcomes of allograft pancreatectomy based on a single center experience. Between 2003 and 2013, 47 patients developed pancreas allograft failure, excluding mortality with a functioning pancreas allograft. Early graft loss (within 14 days) occurred in 16, and late graft loss in 31. All patients with early graft loss eventually required allograft pancreatectomy. Nineteen of 31 patients (61%) with late graft loss underwent allograft pancreatectomy. The main indication for early allograft pancreatectomy included vascular thrombosis with or without severe pancreatitis, whereas one recipient required urgent allograft pancreatectomy for gastrointestinal hemorrhage secondary to an arterioenteric fistula. In cases of late allograft pancreatectomy, graft failure with clinical symptoms such as abdominal discomfort, pain, and nausea were the main indications (13/19 [68%]), simultaneous retransplantation without clinical symptoms in 3 (16%), and vascular catastrophes including pseudoaneurysm and enteric arterial fistula in 3 (16%). Postoperative morbidity included one case each of pulmonary embolism leading to mortality, formation of pseudoaneurysm requiring placement of covered stent, and postoperative bleeding requiring relaparotomy eventually leading to femoro-femoral bypass surgery 2 years after allograftectomy. Allograft pancreatectomy can be performed safely, does not preclude subsequent retransplantation, and may be lifesaving in certain instances.

Conversion from tacrolimus to belatacept to prevent the progression of chronic kidney disease in pancreas transplantation: case report of two patients.

Belatacept is a novel immunosuppressive agent that may be used as an alternative to calcineurin inhibitors (CNI) in immunosuppression (IS) regimens. We report two cases of pancreas transplant that were switched from tacrolimus (TAC) to belatacept. Case 1: 38-year-old female with pancreas transplant alone maintained on TAC-based IS regimen whose serum creatinine (SCr) slowly deteriorated from 0.6 mg/dL at baseline to 2.2 mg/dL, 16 months posttransplant. A native kidney biopsy performed showed CNI toxicity. The patient was started on belatacept and TAC was eliminated. Case 2: 49-year-old female with simultaneous pancreas-kidney transplant, maintained on TAC-based regimen where the SCr worsened over an initial 3-month period from a baseline of 1.0 to 3.0 mg/dL. Belatacept was started and TAC was lowered. Due to persistent graft dysfunction and kidney transplant biopsy still showing changes consistent with CNI toxicity, the TAC was then discontinued. At >1 year postbelatacept and off TAC follow-up, kidney function as measured by SCr remains stable at 1.0±0.2 mg/dL in both recipients. Neither patient developed rejection following the switch, and pancreas allograft function remains stable in both recipients.

Simultaneous pancreas and kidney transplantation with concurrent allograft nephrectomy for recipients with prior renal transplants lost to BK virus nephropathy: two case reports.

Candidacy for retransplantation after allograft loss due to BK virus-associated nephropathy (BKVN) with or without allograft nephrectomy is controversial. This report describes 2 renal transplant recipients who lost their grafts to BKVN and subsequently underwent simultaneous kidney and pancreas transplantation with allograft nephrectomy.

Immediate retransplantation for pancreas allograft thrombosis.

Early pancreas allograft failure most commonly results from thrombosis and requires immediate allograft pancreatectomy. Optimal timing for retransplantation remains undefined. Immediate retransplantation facilitates reuse of the same anatomic site before extensive adhesions have formed. Some studies suggest that early retransplantation is associated with a higher incidence of graft loss. This study is a retrospective review of immediate pancreas retransplants performed at a single center. All cases of pancreas allograft loss within 2 weeks were examined. Of 228 pancreas transplants, 12 grafts were lost within 2 weeks of surgery. Eleven of these underwent allograft pancreatectomy for thrombosis. One suffered anoxic brain injury and was not a retransplantation candidate, one was retransplanted at 3.5 months and nine patients underwent retransplantation 1-16 days following the original transplant. Of the nine early retransplants, one pancreas was lost to heparin-induced thrombocytopenia, one recipient died with function at 2.9 years and the other grafts continue to function at 76-1137 days (mean 572 days). One-year graft survival for early retransplantation was 89% compared to 91% for all pancreas transplants at our center. Immediate retransplantation following pancreatic graft thrombosis restores durable allograft function with outcomes comparable to first-time pancreas transplantation.

Do we need to measure total serum IgA to exclude IgA deficiency in coeliac disease?

BACKGROUND: Screening for IgA deficiency in patients with coeliac disease is essential because of the increased incidence of IgA deficiency associated with the disease, which usually relies on the estimation of IgA levels in each case. AIM: To devise a method of excluding IgA deficiency without measuring total serum IgA in each case. MATERIALS AND METHODS: The optical density readings on enzyme-linked immunosorbent assay (ELISA) of 608 routine samples received for tissue transglutaminase (TTG) antibody testing for coeliac disease were compared with their total IgA concentrations. Dilution experiments were also carried out to ensure linear relationships between optical density on ELISA and IgA concentrations and to compare the sensitivities for TTG and endomysium antibodies in TTG-positive samples. RESULTS AND DISCUSSION: A clear relationship was shown between total IgA concentration and TTG optical density readings by ELISA. To ensure a positive TTG result if antibodies are present, it was possible to recommend an optical density level above which all samples have sufficient IgA. Samples with optical density <0.05 should be investigated further by estimating total IgA and, if low, samples should be subjected to immunofluorescence microscopy testing for IgA and IgG endomysium antibodies. CONCLUSIONS: An easier, more cost-effective and practical way of excluding IgA deficiency in the investigation on coeliac disease is reported.

The kinetics of acylation and deacylation of penicillin acylase from Escherichia coli ATCC 11105: evidence for lowered pKa values of groups near the catalytic centre.

Penicillin G acylase catalysed the hydrolysis of 4-nitrophenyl acetate with a kcat of 0.8 s-1 and a Km of 10 microM at pH 7.5 and 20 degreesC. Results from stopped-flow experiments fitted a dissociation constant of 0.16 mM for the Michaelis complex, formation of an acetyl enzyme with a rate constant of 32 s-1 and a subsequent deacylation step with a rate constant of 0.81 s-1. Non-linear Van't Hoff and Arrhenius plots for these parameters, measured at pH 7.5, may be partly explained by a conformational transition affecting catalytic groups, but a linear Arrhenius plot for the ratio of the rate constant for acylation relative to KS was consistent with energy-compensation between the binding of the substrate and catalysis of the formation of the transition state. At 20 degreesC, the pH-dependence of kcat was similar to that of kcat/Km, indicating that formation of the acyl-enzyme did not affect the pKa values (6.5 and 9.0) of an acidic and basic group in the active enzyme. The heats of ionization deduced from values of pKa for kcat, which measures the rate of deacylation, are consistent with alpha-amino and guanidinium groups whose pKa values are decreased in a non-polar environment. It is proposed that, for catalytic activity, the alpha-amino group of the catalytic SerB1 and the guanidinium group of ArgB263 are required in neutral and protonated states respectively.

Sudden cardiac death in the young athlete.

Sudden cardiac death in athletes is usually due to underlying cardiovascular disease. In the young less than 30 years of age, the most common abnormality is hypertrophic cardiomyopathy, followed by congenital coronary artery anomalies. The final common pathway is usually ventricular fibrillation. Sudden cardiac death in the young is rare but remains a source of concern. A careful screening history and physical examination, especially for potential athletes, should identify the majority of young people at risk.

Tracking of left ventricular mass in children: race and sex comparisons: the MCV Twin Study. Medical College of Virginia.

BACKGROUND: Increased left ventricular (LV) mass is a predictor of cardiovascular disease in adults. The mechanism(s) for these observations are not fully understood. METHODS AND RESULTS: We repeatedly studied a biracial sample of children from ages 11 through 17 years. At visits 1 through 5, height, weight, and pubertal stage were determined. Blood pressure and heart rate were measured. M-mode and two-dimensional echocardiograms were performed with a 3.5-MHz transducer with the subject in the supine position. LV mass was calculated. Repeated-measures analysis using a mixed modeling approach was performed for LV mass. At all ages, boys had greater LV mass than girls. For the population as a whole, we found significant tracking correlations for LV mass between each interval of measurement and throughout the entire period of examination. The tracking correlation for the entire sample from visit 1 through visit 5 was r=.41. The LV mass in white children tracked from the youngest to the oldest. Black children tracked similarly from ages 1 to 15 years, but tracking was not significant across the widest interval, visit 1 through visit 5. Racial differences were found in the interactions of systolic blood pressure and heart rate, which magnified the differences in LV mass. During adolescence, LV mass tracks significantly in both black and white children. CONCLUSIONS: Interactive effects such as weight, blood pressure, and heart rate magnify sex and race differences in LV mass.

Different sensitivities to acid denaturation within a family of proteins: implications for acid unfolding and membrane translocation.

Colicins A, B, and N form a family of membrane pore-forming toxins with > 50% sequence identity in their toxic C-terminal domains. The colicin A C-terminal domain has been shown to insert into model membranes via an acidic molten-globule insertion intermediate, and thus this family provides a means to compare acid unfolding of related proteins. Unlike the domains of colicins A and B which are acidic, that of colicin N is very basic with fewer Asp and Glu residues. If surface positive charge density is the crucial factor in acidic molten globule formation, colicin N should begin to unfold at higher pH values than colicins A or B. However, comparison of their CD spectra reveals that colicins A and B both form acidic molten globules but colicin N does not. None of the proteins forms a denaturant-induced molten globule at neutral pH where the proteins exhibit very similar stabilities. The acidic unfolding cannot therefore be due to excess positive surface charge and may be caused by a subset of acidic residues as has been predicted for myoglobin. The difference between the colicins is confirmed by their in vivo membrane insertion, with colicins A and B inserting much faster than colicin N. Stopped-flow circular dichroism measurements of colicin A insertion into vesicles confirmed that a molten globule insertion intermediate occurs at the membrane surface.

Rapid burst kinetics in the hydrolysis of 4-nitrophenyl acetate by penicillin G acylase from Kluyvera citrophila. Effects of mutation F360V on rate constants for acylation and de-acylation.

The kinetics of release of 4-nitrophenol were followed by stopped-flow spectrophotometry with two 4-nitrophenyl ester substrates of penicillin G acylase from Kluyvera citrophila. With the ester of acetic acid, but not of propionic acid, there was a pre-steady-state exponential phase, the kinetics of which were inhibited by phenylacetic acid (a product of hydrolysis of specific substrates) to the extent predicted from Ki values. This was interpreted as deriving from rapid formation (73 mM-1.s-1) and slow hydrolysis (0.76 s-1) of an acetyl derivative of the side chain of the catalytic-centre residue Ser-290. With the mutant F360V, which differs from the wild-type enzyme in its ability to hydrolyse adipyl-L-leucine and has a kcat for 4-nitrophenyl acetate one-twentieth that of the wild-type enzyme, the corresponding values for the rates of formation and hydrolysis of the acetyl-enzyme were 11.1 mM-1.s-1 and 0.051 s-1 respectively. The ratio of these rate constants was three times that for the wild-type enzyme, suggesting that the mutant is less impaired in the rate of formation of an acetyl-enzyme than in its subsequent hydrolysis.

Genetic influences on ambulatory blood pressure patterns. The Medical College of Virginia Twin Study.

The genetic influence of ambulatory blood pressure and heart rate was examined in 38 pairs of monozygotic twins, 17 pairs of same-sex dizygotic twins, and 11 pairs of opposite-sex dizygotic twins, all aged 15 or 17 years. The data were analyzed taking into consideration that the response was multivariate (24-h values) instead of the usual univariate response. The results demonstrated the heritability of ambulatory blood pressure and heart rate. This was true regardless of whether the estimate of heritability involved monozygotic twin pairs compared to same-sex dizygotic twin pairs only, or all dizygotic twin pairs. The time-related intraclass correlation coefficient within each twin classification indicated that the patterns of response within twin pairs correlated more for monozygotic twin pairs than within twin pairs for either set of dizygotic twin pairs. In addition, although the opposite-sex dizygotic twin pairs may have different mean levels of response, they exhibit a similarity of patterns of response akin to that seen within same-sex dizygotic twin pairs.

New insights on the specificity of penicillin acylase.

In contrast with the general thought that penicillin G acylases (PGAs) were only able to hydrolyse amides or esters of higly hydrophobic acids, we have demonstrated that the PGA from Kluyvera citrophila catalysed the hydrolysis of 4-nitrophenyl esters of acetic, propionic, butyric and valeric acids. Values of kcat. and kcat./Km were greatest for the first compound and less than values for benzylpenicillin by factors of 30 and 7, respectively. 4-Nitrophenyl acetate was hydrolysed faster than 2-nitrophenyl acetate but slower than phenyl acetate. The pH dependence of the reaction was similar to that of benzylpenicillin. Several experiments showed that hydrolysis of 4-nitrophenyl acetate was not catalysed by contaminating esterase activity. The implications for the structural basis of substrate binding are discussed. These substrates open, for the first time, a way to investigate the kinetic parameters of PGA at the presteady-state and provides a new perspective about the role of PGA in nature.

Altered blood pressure reactivity in adolescent diabetics.

OBJECTIVE: We examined hemodynamic responses to a variety of physiologic stimuli in 14 normotensive adolescents with type I diabetes and 45 healthy controls to determine whether structural vascular changes contribute to a reduced vasodilator capacity in adolescent diabetics. We asked, in adolescents with type I diabetes: (1) Are structural vascular changes present? (2) Are changes in the systemic vascular bed reflected in abnormal blood pressure regulation? and (3) Is abnormal vascular reactivity associated with either diabetes duration or control? METHODOLOGY: Diabetic subjects were outpatients treated at the Medical College of Virginia, ages 13 to 18 years. Diabetes duration averaged 7.5 years. Each subject underwent an echocardiogram, dynamic and isometric exercise testing, and forearm plethysmography. RESULTS: Compared to controls, diabetic subjects had (1) higher systolic and diastolic blood pressure during dynamic and handgrip exercise, (2) decreased forearm vasodilator capacity in response to ischemia, and (3) an increased aortic peak velocity. Group diastolic filling abnormalities were found, but these did not persist after adjustment for heart rate. The following variables were related to both diabetes duration and control (average glycosylated hemoglobin): (1) diastolic blood pressure during dynamic exercise, (2) resting forearm vascular resistance, and (3) forearm vascular reactivity. In addition, diabetes duration correlated with isometric exercise diastolic blood pressure, and diabetes control correlated with resting diastolic blood pressure. CONCLUSION: In young diabetics we found that (1) abnormalities of the resistance vessels of the forearm may be present, (2) the degree of vascular change is related to diabetes duration and control, and (3) aortic distensibility may be impaired.

Quantitative measurement of drug susceptibility of Mycobacterium tuberculosis for monitoring chemotherapy response.

Changes in the degree of drug susceptibility of the bacterial population in tuberculosis patients during chemotherapy can be monitored by testing Mycobacterium tuberculosis isolates against various concentrations of drugs in 7H12 broth to determine radiometrically the minimal inhibitory concentration (MIC). The MICs were determined for multiple cultures isolated from 13 patients, of whom nine responded to chemotherapy within a few months, and four failed to respond at all. No changes in MICs were observed with the isolates obtained from the patients with a favorable response to chemotherapy. Determination of the MICs indicated that the failure in two cases out of four was associated with a steady increase in the degree of resistance of the patients' bacterial population. In two other failure cases, lack of change in the MIC values for multiple cultures suggests that the failure was associated with factors other than drug resistance. During the period of chemotherapy, quantitation of the degree of drug susceptibility in terms of broth-determined MICs may help to identify promptly those patients whose bacterial population is becoming resistant to the administered antimicrobial agents. For those patients who do not respond to chemotherapy, lack of change in the degree of resistance of their bacterial population may alert the physician to attempt to identify causes other than drug resistance for the chemotherapy failure.

Acute monoblastic leukemia presenting with pericardial effusion and cardiac tamponade.

A previously healthy young child presented with a large pericardial effusion and cardiac tamponade. The chest radiography was key to the recognition of the pericardial effusion. Cytologic examination of the pericardial fluid ultimately established the diagnosis of acute monoblastic leukemia in the absence of associated clinical or laboratory findings. The pericardial fluid was vital for leukemic cell classification because the bone marrow has hypocellular and non-diagnostic. This presentation of acute monoblastic leukemia is very rare, and in the three previously reported pediatric cases has been associated either with peripheral blasts or a history of preleukemia. When the cardiac configuration suggests pericardial effusion in a previously healthy young child, the diagnosis of new onset leukemia should be considered.