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Biomedical subjects

R Shapiro

Publications and source records attributed to R Shapiro.

At least 73 records · Page 4Linked to original sources
PubMed1999

Refined crystal structures of native human angiogenin and two active site variants: implications for the unique functional properties of an enzyme involved in neovascularisation during tumour growth.

Human angiogenin (Ang), an unusual member of the pancreatic RNase superfamily, is a potent inducer of angiogenesis in vivo. Its ribonucleolytic activity is weak (10(4) to 10(6)-fold lower than that of bovine RNase A), but nonetheless seems to be essential for biological function. Ang has been implicated in the establishment of a wide range of human tumours and has therefore emerged as an important target for the design of new anti-cancer compounds. We report high-resolution crystal structures for native Ang in two different forms (Pyr1 at 1.8 A and Met-1 at 2.0 A resolution) and for two active-site variants, K40Q and H13A, at 2.0 A resolution. The native structures, together with earlier mutational and biochemical data, provide a basis for understanding the unique functional properties of this molecule. The major structural features that underlie the weakness of angiogenin's RNase activity include: (i) the obstruction of the pyrimidine-binding site by Gln117; (ii) the existence of a hydrogen bond between Thr44 and Thr80 that further suppresses the effectiveness of the pyrimidine site; (iii) the absence of a counterpart for the His119-Asp121 hydrogen bond that potentiates catalysis in RNase A (the corresponding aspartate in Ang, Asp116, has been recruited to stabilise the blockage of the pyrimidine site); and (iv) the absence of any precise structural counterparts for two important purine-binding residues of RNase A. Analysis of the native structures has revealed details of the cell-binding region and nuclear localisation signal of Ang that are critical for angiogenicity. The cell-binding site differs dramatically from the corresponding regions of RNase A and two other homologues, eosinophil-derived neurotoxin and onconase, all of which lack angiogenic activity. Determination of the structures of the catalytically inactive variants K40Q and H13A has now allowed a rigorous assessment of the relationship between the ribonucleolytic and biological activities of Ang. No significant change outside the enzymatic active site was observed in K40Q, establishing that the loss of angiogenic activity for this derivative is directly attributable to disruption of the catalytic apparatus. The H13A structure shows some changes beyond the ribonucleolytic site, but sites involved in cell-binding and nuclear translocation are essentially unaffected by the amino acid replacement.

Amino Acid Sequence↗
PubMed1999

Clinical significance of renal biopsies showing concurrent acute rejection and tacrolimus-associated tubular vacuolization.

BACKGROUND: The clinical significance of biopsies showing both rejection and isometric tubular vacuolization has not been well defined in the literature. METHODS: The clinical picture, sequential histopathologic findings, and response to therapy were compared between 24 renal allograft biopsies showing both tubular vacuolization and rejection and 14 biopsies showing vacuolization alone. RESULTS: The rejection was categorized as grade 1 in 4/24 (16.6%), grade 2A in 10/24 (41.6%), and grade 2B in 10/24 (41.6%) cases (Banff schema, 1993-1995). Treatment with additional steroids and tacrolimus led to a decrease in the interstitial inflammation score (2.6+/-0.1 to 1.3+/-0.1, P<0.001), tubulitis score (2.6+/-0.1 to 1.1+/-0.1, P<0.001), and serum creatinine (4.4+/-2.2 mg/dl to 3.3+/-2.6 mg/dl, P=0.001). Complete response, partial response and no response to antirejection therapy were observed in 16/24 (66.7%), 3/24 (12.5%), and 5/24 (20.8%) patients, respectively. Although there was a rise in the plasma (1.4+/-0.2 ng/ml to 2.8+/-0.3 ng/ml, P<0.001) and whole blood (16.5+/-2.8 ng/ml to 31.2+/-5.7 ng/ml, P<0.001) tacrolimus levels, repeat biopsy showed no change in the size or extent of tubular vacuolization (mean score 2.88+/-0.19 vs. 2.83+/-0.21). The morphologic characteristics of the tubular vacuoles in these cases did not differ from those observed in 14 cases of tacrolimus nephrotoxicity not complicated by rejection. CONCLUSION: Patients with concurrent acute rejection and tubular vacuolization usually benefit from increased immunosuppression. The pathogenesis of the vacuolization in this clinical setting is not clear, but may reflect immune-mediated tubular injury.

Acute Disease↗
PubMed1999

The clinical significance of cytomegaloviral inclusions in the allograft kidney.

BACKGROUND: Renal allografts are a frequent site of subclinical cytomegalovirus (CMV) infection diagnosed by culture, but histologic inclusions occur in less than 1% of biopsies. The natural history of this subgroup of patients has been reported only occasionally, mostly before the availability of ganciclovir therapy. METHODS: We analyzed the clinical parameters and pathologic findings in 10 patients with CMV inclusions at allograft biopsy. RESULTS: The patients were 29-72 years old, and 9 of 10 (90%) had previous episodes of acute rejection, 3 of whom needed OKT3 administration. Histopathologic examination of the allografts showed interstitial inflammation with tubulitis in 7 of 10 (70%) patients; in 3 of 10 (30%) patients, viral inclusions were present in the glomerular capillary endothelia without any associated inflammatory response. Morphologic criteria for acute transplant glomerulopathy or proliferative glomerulonephritis were not satisfied. Extrarenal viral inclusions were documented in the gastrointestinal tracts of 2 of 10 (20%) patients. The patients were treated with reduced immunosuppression and ganciclovir. Five patients lost their grafts 56.6+/-86.6 days (range, 4-210 days; median, 21 days) after initial diagnosis. The serum creatinine in the remaining five patients was 3.3+/-2.0 mg/dl (range, 1.2-6.5 mg/dl; median, 2.5 mg/dl) 77+/-16 days (range, 56-101 days; median, 77 days) after transplantation. Histopathologic examination showed no residual viral inclusions in 5 of 7 (71.4%) follow-up specimens available for examination. CONCLUSIONS: CMV inclusions in renal allograft biopsies typically occur after treatment for rejection. Ganciclovir eradicates replicative virus, but graft outcome is determined by coexisting acute rejection and chronic allograft nephropathy. Graft loss primarily attributable to CMV was not observed.

Adult↗
PubMed1999

Human polyoma virus-associated interstitial nephritis in the allograft kidney.

BACKGROUND: Asymptomatic polyoma virus infection documented by urine cytology or serology is well known, but the clinical course of biopsy-proven interstitial nephritis is not well defined. METHODS: Twenty-two cases were identified by histology, immunostaining, in situ hybridization, electron microscopy, or polymerase chain reaction. RESULTS: The clinical features mimicked acute rejection (n=19), chronic rejection with incidental diagnosis at nephrectomy (n=2), or drug toxicity (n=1). Histology showed homogenous intranuclear inclusions. In situ hybridization showed BK virus (BKV) to be the predominant species, but polymerase chain reaction documented JC virus co-infection in one of five cases so tested. Electron microscopy in seven cases showed 20-51-nm virions. The two cases diagnosed at nephrectomy received no therapy. Initial antirejection therapy in 12 cases led to clearance of the virus in 1/12 (8%), partial therapeutic response in 3/12 (25%), and graft loss in 8/12 (67%) cases. The last recorded creatinine in patients with functional grafts ranged from 1.9 to 7.0 (median: 4.5) mg/dl, 0.4-45 (median: 4.0) months after initial diagnosis. The remaining eight cases treated by reduction of immunosuppression at the outset have been free of graft loss for 0.2-10.0 (median: 4.8) months since diagnosis, and clearance of virus has been documented in three of six (50%) cases. The serum creatinine in these patients is 1.7-6.0 (median: 2.4) mg/dl, 0.2-10 (median: 4.8) months after diagnosis. Follow-up biopsies performed 1-23.5 months after diagnosis show chronic allograft nephropathy. CONCLUSIONS: Polyoma virus tubulo-interstitial nephritis-associated graft dysfunction usually calls for judicious decrease in immunosuppression and monitoring for acute rejection. Development of methods to serially quantify the viral load in individual patients could potentially improve clinical outcome.

Adolescent↗
PubMed1999

Infusion of donor leukocytes to induce tolerance in organ allograft recipients.

To further enhance chimerism, 229 primary allograft recipients have received perioperative intravenous infusion of a single dose of 3 to 6 X 10(8) unmodified donor bone marrow (BM) cells/kg body weight. In addition, 42 patients have been accrued in a concurrent protocol involving multiple (up to three) sequential perioperative infusions of 2 x 10(8) BM cells/kg/day from day 0-2 posttransplantation (PTx). Organ recipients (n = 133) for whom BM was not available were monitored as controls. The infusion of BM was safe and except for 50 (18%), all study patients have optimal graft function. Of the control patients, allografts in 30 (23%) have been lost during the course of follow-up. The cumulative risk of acute cellular rejection (ACR) was statistically lower in the study patients compared with that of controls. It is interesting that, 62% of BM-augmented heart recipients were free of ACR (Grade > or = 3A) in the first 6 months PTx compared to controls. The incidence of obliterative bronchiolitis was also statistically lower in study lung recipients (3.8%) compared with the contemporaneously acquired controls (31%). The levels of donor cell chimerism were at least a log higher in the peripheral blood of majority of the study patients compared with that of controls. The incidence of donor-specific hyporeactivity, as determined by one-way mixed leukocyte reaction, was also higher in those BM-augmented liver, kidney, and lung recipients that could be evaluated compared to controls.

Bone Marrow Cells↗
PubMed1999

Hamstring extensibility and transverse plane knee control relationship in athletic women.

Athletic women are at particular risk for sustaining a non-contact anterior cruciate ligament (ACL) injury. The hamstrings are vital to providing dynamic knee motion control in the sagittal and transverse planes during running stance, and some have suggested this function is enhanced when they are less extensible. This study attempted to determine the correlational relationships between hamstring extensibility and transverse plane knee kinematics and from these data to describe the dynamic transverse plane knee motion control capabilities of the hamstrings. Twenty normal athletic women (mean +/- SD; aged 21 +/- 1.6 years; height 163.3 +/- 5.7 cm; weight 60.1 +/- 3.6 kg) were evaluated for active hamstring extensibility and transverse plane knee kinematic relationships during crossover-cut stance phase. Following crossover-cut training (3 weeks) using the left (preferred) lower extremity as the stance limb, hamstring extensibility was measured. Following this, subjects were fitted with 9 retroreflective markers denoting the local segmental coordinate systems (3 markers each) of the left foot, leg and thigh. Kinematic (3-dimensional, four phase-locked cameras, 200 Hz) knee and ankle data were sampled and analyzed. Descriptive statistics and Pearson correlations between hamstring extensibility and knee and ankle kinematic variables were calculated. Statistical significance was set at P < or = 0.05 with Bonferroni adjustments. Hamstring extensibility (12 degrees +/- 8 degrees terminal extension) revealed low but significant positive correlations with tibial external rotation (6 degrees +/- 10.7 degrees) at heelstrike (19.3 degrees +/- 8.5 degrees knee flexion) (r = 0.62, P = 0.004) and tibial internal rotation (-13 degrees +/- 8.4 degrees) at peak knee flexion (57.8 degrees +/- 9.3 degrees) following heelstrike (r = 0.47, P = 0.01). Increased hamstring extensibility resulted in increased tibial external rotation at heelstrike and decreased tibial internal rotation at peak knee flexion. Increased hamstring extensibility may improve knee extensor efficiency at heelstrike by enabling greater tibial external rotation and protect the ACL at peak knee flexion by decreasing the tibial internal rotation magnitude.

Adult↗
PubMed1999

Cytomegalovirus infection of the native ureter after liver-kidney transplantation.

We report a case of invasive cytomegalovirus (CMV) infection in the native ureter of a patient 7 years after liver-kidney transplantation. Previous reports of CMV ureteritis in transplant patients have involved only the allograft ureter, usually within 3 months of transplantation. The common characteristics of these patients, the possible risk factors, and the diagnostic findings of CMV ureteritis are discussed. Combined surgical and medical intervention are required for successful treatment.

Adult↗
PubMed1999

A dentoalveolar abscess in a pediatric patient with ketoacidosis caused by occult diabetes mellitus: a case report.

Oral health professionals are frequently asked to evaluate patients with routine odontogenic infections. These patients can sometimes present with systemic signs and symptoms, including fever, malaise, tachycardia, and dehydration. It is important for the astute clinician to understand the possible associated systemic diseases that may be contributing to odontogenic infections. We present here an interesting case of a pediatric patient with a routine canine space infection who exhibited classic clinical signs and symptoms of diabetic ketoacidosis.

Child, Preschool↗
PubMed1999

Conformational analysis of the major DNA adduct derived from the food mutagen 2-amino-3-methylimidazo[4,5-f]quinoline.

The heterocyclic amine 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) is one of a number of carcinogens found in barbecued meat and fish. It is mutagenic in bacterial and mammalian assays and induces tumors in mammals. IQ is biochemically activated to a derivative which reacts with DNA to form a major covalent adduct at carbon 8 of guanine. This adduct may deform the DNA and consequently cause a mutation, which may be responsible for initiating IQ's carcinogenicity. Atomic resolution structures of the IQ-damaged DNA are not yet available experimentally. We have carried out an extensive molecular mechanics energy minimization search to locate feasible structures for the major IQ-DNA adduct in the representative sequence d(5'-G1-G2-C3-G4-C5-C6-A7-3'). d(5'-T8-G9-G10-C11-G12-C13-C14-3') with IQ modification at G4; this contains the GGCGCC mutational hotspot sequence known as NarI. The molecular mechanics program AMBER 5.0 with the force field of Cornell et al. [(1995) J. Am. Chem. Soc. 117, 5179-5197] was employed, including explicit Na(+) counterions and an implicit treatment for solvation. However, key parameters, the partial charges, bond lengths, bond angles, and dihedral parameters of the modified residue, are not available in the AMBER database. We carefully parametrized the force field, created 800 starting conformations which uniformly sampled at 18 degrees intervals each of the three flexible torsion angles that govern the IQ-DNA orientation, and minimized their energy. A conformational mix of structural types, including major groove, minor groove, and base-displaced intercalated carcinogen positions, was generated. This mixture may be related to the diversity of mutational outcomes induced by IQ.

Chemical Phenomena↗
PubMed1999

Prevention and treatment of cytomegalovirus infection in organ transplant recipients.

Cytomegalovirus (CMV) is the most common viral pathogen in organ transplant recipients. The patients at highest risk of developing CMV disease are seronegative recipients of seropositive donors, and seropositive recipients who receive antilymphocyte agents such as OKT3 and antithymocyte globulin (ATG) for induction or for rejection. There have been many trials of CMV prevention, but they are difficult to compare with one another because of variability in definitions and end points. Two modalities that have been used to prevent CMV disease are prophylaxis and preemptive therapy. In prophylaxis all patients are given an antiviral agent in order to prevent CMV disease, while in preemptive therapy (also called targeted prophylaxis) only patients who are identified as 'high risk' are selected for treatment. Selected trials of prophylaxis and preemptive therapy in solid-organ recipients are reviewed. The factors to be considered in using one modality or the other are side effects from antivirals, cost of monitoring and antivirals, efficacy of the two modalities, and potential emergence of drug resistance. Sensitive tests that have been used for early diagnosis and monitoring of CMV are antigenemia and the polymerase chain reaction (PCR). Antigen pp65 is a lower matrix protein and can be detected in peripheral blood leukocytes. The sensitivity and specificity are high and vary from 89% to 100% and 92% to 96%, respectively. Currently, many authors believe that the antigenemia test is more useful than the PCR test. The antigenemia test is useful for viral monitoring as a guide for preemptive therapy after organ transplantation. Persistence of high counts of antigenemia may indicate inadequate antiviral therapy or emergence of resistance. Recurrence of positive antigenemia after treatment of CMV disease can be a sign of relapse. Transplant patients who develop resistance to antiviral drugs are usually seronegative recipients who receive an organ from a seropositive donor and have several courses of antivirals for CMV disease. Ganciclovir is the most frequent antiviral agent used in transplant recipients and is usually well tolerated. Resistance to ganciclovir may occur and is usually secondary to virus mutation in the UL97 gene. The availability of sensitive diagnostic tests such as pp65 antigenemia has made the early diagnosis of CMV possible in organ transplant recipients. CMV is being treated much earlier now, and progression to disseminated disease is uncommon. Prudent use of antiviral drugs will hopefully limit the problem of drug resistance.

Antiviral Agents↗
PubMed1999

Simultaneous administration of adjuvant donor bone marrow in pancreas transplant recipients.

OBJECTIVE: The effect of donor bone marrow was evaluated for its potentially favorable effect in the authors' simultaneous pancreas/kidney transplant program. METHODS: From July 1994 to January 1999, 177 pancreas transplants were performed, 151 of which were simultaneous pancreas/kidney transplants. All patients received tacrolimus, mycophenolate mofetil, and steroids for immunosuppression (azathioprine was used in the first year of the program). Fifty-three simultaneous pancreas/kidney transplant recipients received perioperative unmodified donor bone marrow, 3 to 6 x 10(8) cells/kg. RESULTS: Overall actuarial survival rates at 1 and 3 years were 98% and 95% (patient), 95% and 87% (kidney), and 86% and 80% (pancreas), respectively. In the adjuvant bone marrow group, 1- and 3-year survival rates were 96% and 91 % (patient), 95% and 87% (kidney), and 83% and 83% (pancreas), respectively. For 98 recipients who did not receive bone marrow, survival rates at 1 and 3 years were 100% and 98% (patient), 96% and 86% (kidney), and 87% and 79% (pancreas), respectively. No pancreas allografts were lost after 3 months in bone marrow recipients, and seven in the non-bone marrow recipients were lost to rejection at 0.7, 6.7, 8.8, 14.6, 24.1, 24.3, and 25.5 months. Twenty-two percent of bone marrow patients were steroid-free at 1 year, 45% at 2 years, and 67% at 3 years. Nineteen percent of the non-bone marrow recipients were steroid-free at 1 year, 38% at 2 years, and 45% (p = 0.02) at 3 years. The mean acute cellular rejection rate was 0.94+/-1.1 in the bone marrow group and 1.57+/-1.3 (p = 0.003) in the non-bone marrow group (includes borderline rejection and multiple rejections). The level of donor cell chimerism in the peripheral blood of bone marrow patients was at least two logs higher than in controls. CONCLUSION: In this series, which represents the largest experience with adjuvant bone marrow infusion in pancreas recipients, there was a higher steroid withdrawal rate (p = 0.02), fewer rejection episodes, and no pancreas graft loss after 3 months in bone marrow recipients compared with contemporaneous controls. All pancreas allografts lost to chronic rejection (n = 6) were in the non-bone marrow group. Donor bone marrow administered around the time of surgery may have a protective effect in pancreas transplantation.

Actuarial Analysis↗
PubMed1999

Case series: clonidine has no systematic effects on PR or QTc intervals in children.

This study retrospectively examined the effects of clonidine, both alone and combined with psychostimulants, on the electrocardiograms (ECGs) of children and adolescents. Two pediatric cardiologists, blinded to treatment condition, examined pre- and posttreatment ECGs in 42 subjects treated with clonidine for attention-deficit/hyperactivity or tic disorder. While ECG variability was found, it did not appear to be related to any systematic effect of clonidine, either alone or in combination with psychostimulants. These data do not rule out the possibility of rare idiosyncratic reactions to clonidine with or without psychostimulants, though none occurred in this sample.

Adolescent↗
PubMed1999

Shoulder proprioception: latent muscle reaction times.

PURPOSE: The purpose of this study was to identify electromyographic (EMG) differences in the latent muscle reaction timing (LMRT) of the rotator cuff between trained overhead throwers and control subjects in response to sudden internal rotation perturbation (P < or = 0.05). METHODS: Subjects included 15 trained overhead throwers (male intercollegiate baseball players) and 15 untrained subjects (males not active in competitive throwing sports). Subjects were tested while seated, with their dominant glenohumeral joint positioned in 90 degrees abduction/external rotation (scapular plane), their elbow flexed to 90 degrees, and their forearm placed in the perturbation device. Rotator cuff LMRT was assessed as they tried to decelerate a variably timed, sudden internal rotation force. EMG sampling (2000 Hz, 2-s duration) began immediately before perturbation. RESULTS: Trained throwers had slower infraspinatus (P = 0.011) and teres minor (P = 0.024) LMRT and decreased supraspinatus (P = 0.001) and posterior deltoid (P = 0.0001) muscle activation duration compared with control subjects. CONCLUSIONS: These results suggest that the rotator cuff muscles of trained throwers may be downregulated in response to sudden internal rotation perturbation. Although these adaptations would enable greater internal rotation velocities during overhead throwing, they may also contribute to glenohumeral joint pathology. The identification of changes in rotator cuff LMRT in response to sudden internal rotation perturbation suggests an area of acquired neuromuscular imbalance warranting consideration by those involved in the rehabilitation and conditioning of the overhead throwing athlete.

Adolescent↗
PubMed1999

The epidermotropic mycosis fungoides associated alpha1beta1 integrin (VLA-1, CD49a/CD29) is primarily a collagen IV receptor on malignant T cells.

Several of the beta1 integrin receptors [very late antigen (VLA) molecules] for extracellular matrix (ECM) proteins are expressed by malignant T cells in cutaneous T-cell lymphoma (CTCL). We evaluated the function of VLA-1, a beta1 integrin specifically expressed in epidermotropic mycosis fungoides (MF), in CD4+ leukemic T cells Jurkat line). We found that Jurkat cells adhere significantly to collagens only after their activation with phorbol 12-myristate 13-acetate (PMA). However, the adhesion to collagen IV (but not to collagen I) of Jurkat cells selected for expressing increased levels of VLA-1 (with unchanged levels of VLA-2, the second collagen integrin receptor) was significantly enhanced relative to that of "VLA-1 low" cells. Monoclonal antibody (mAb) 1B3.1, directed against the collagen binding domain of VLA-1, inhibited adhesion to collagen IV and to collagen I by 36.67%+/-5.25% and 18%+/-4.32%, respectively (p<0.05), whereas the inhibition by anti-VLA-2 mAb PIE6 was comparable on both collagens (25%+/-7.48% and 36.3%+/-0.94%, respectively; p<0.09). Immuno-histochemical studies of skin biopsies from 10 untreated MF patients showed that in all cases at least 10% of the lymphocytes residing in the epidermis are VLA-1+VLA-2-. While not directly applicable to MF, the demonstrated functions of VLA-1 in leukemic Jurkat cells, together with its expression in MF skin, suggest a role for VLA-1 integrins in epidermotropism in a small proportion of leukemic MF cells.

Antigens, CD↗
PubMed1999

mAngiogenin-3, a target gene of oncoprotein E2a-Pbx1, encodes a new angiogenic member of the angiogenin family.

Angiogenins are proteins in the pancreatic ribonuclease superfamily that utilize their ribonuclease activity to induce formation of new blood vessels. Recently we identified a new member of the angiogenin gene family, mouse angiogenin-3, by virtue of its transcriptional activation in NIH3T3 fibroblasts coincident with transformation by the chimeric leukemia oncogene, E2a-Pbx1. Here we have isolated the cDNA encoding mouse angiogenin-3 and used it to produce the protein in E. coli. We demonstrate that mouse angiogenin-3 is a ribonuclease whose activity and specificity towards tRNA and dinucleotide substrates differ from those of mouse angiogenin or of mouse angiogenin-related protein, a non-angiogenic factor. Mouse angiogenin-3 induced angiogenesis in both the chicken embryo chorioallantoic membrane assay and the rat cremaster muscle. Electron microscopy revealed that endothelial cells within vessels induced by both mouse angiogenin-3 and mouse angiogenin contain fenestrations similar to those observed in endothelial cells from neovasculature induced by vascular endothelial growth factor and basic fibroblast growth factor. Mouse angiogenin-3 also induced other molecular events typical of rapidly proliferating endothelial cells, such as increases in rough endoplasmic reticulum, polysomes, and mitochondria.

3T3 Cells↗