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Biomedical subjects

J Friedman

Publications and source records attributed to J Friedman.

At least 19 recordsLinked to original sources
PubMed2005

Intrinsic joint kinematic planning. I: reassessing the Listing's law constraint in the control of three-dimensional arm movements.

This study tested the validity of the assumption that intrinsic kinematic constraints, such as Listing's law, can account for the geometric features of three-dimensional arm movements. In principle, if the arm joints follow a Listing's constraint, the hand paths may be predicted. Four individuals performed 'extended arm', 'radial', 'frontal plane', and 'random mixed' movements to visual targets to test Listing's law assumption. Three-dimensional rotation vectors of the upper arm and forearm were calculated from three-dimensional marker data. Data fitting techniques were used to test Donders' and Listing's laws. The coefficient values obtained from fitting rotation vectors to the surfaces described by a second-order equation were analyzed. The results showed that the coefficients that represent curvature and twist of the surfaces were often not significantly different from zero, particularly not during randomly mixed and extended arm movements. These coefficients for forearm rotations were larger compared to those for the upper arm segment rotations. The mean thickness of the rotation surfaces ranged between approximately 1.7 degrees and 4.7 degrees for the rotation vectors of the upper arm segment and approximately 2.6 degrees and 7.5 degrees for those of the forearm. During frontal plane movements, forearm rotations showed large twist scores while upper arm segment rotations showed large curvatures, although the thickness of the surfaces remained low. The curvatures, but not the thicknesses of the surfaces, were larger for large versus small amplitude radial movements. In conclusion, when examining the surfaces obtained for the different movement types, the rotation vectors may lie within manifolds that are anywhere between curved or twisted manifolds. However, a two-dimensional thick surface may roughly represent a global arm constraint. Our findings suggest that Listing's law is implemented for some types of arm movement, such as pointing to targets with the extended arm and during radial reaching movements.

Adolescent↗
PubMed2005

Pilot study of 13cis-retinoic acid+dexamethasone+alpha interferon as maintenance therapy following high-dose chemotherapy and autologous stem cell transplant for multiple myeloma.

Interleukin 6 (IL-6) is a major growth factor for myeloma cells and retinoids have been shown to inhibit expression of the interleukin 6 receptor (IL-6R). We performed a pilot study to assess the efficacy and tolerability of 13cis retinoic acid (13cRA) and dexamethasone (Dex), when added to interferon alpha (IFNalpha) as maintenance therapy post autologous stem cell transplantation. Between 90 and 120 days post stem cell transplantation, 33 patients were started on 13cRA 1 mg/kg p.o. daily for 14 days and Dex 40 mg p.o daily for 5 days every month. 13cRA was dose escalated by 0.5 mg/kg/month to 2 mg/kg. Seventeen patients had a persistent paraprotein post transplant. Overall, a response to therapy was observed in 11/17 (64%), with a complete response in 4/17 (23.5%) and a partial response (>/=50% paraprotein decline) in 7/17 (41%). With a median follow-up of 34.8 months, 22/33 (66%) demonstrated disease progression and 11/33 (33%) died. The median progression-free survival from diagnosis was 34.7 months. Although a decline in paraprotein was frequently observed on triple therapy, many patients discontinued therapy due to the side-effects of the IFNalpha. Future trials should be designed using 13cRA and Dex alone.

Adult↗
PubMed2004

Mutations in DYT1: extension of the phenotypic and mutational spectrum.

BACKGROUND: Most cases of early-onset primary torsion dystonia (PTD) are caused by the same three-base pair (bp) (GAG) deletion in the DYT1 gene. Exon rearrangements are a common mutation type in other genes and have not yet been tested for in DYT1. Several lines of evidence suggest a relationship of the DYT1 gene with Parkinson disease (PD). OBJECTIVE: To investigate the frequency and type of DYT1 mutations and explore the associated phenotypes in a mixed movement disorders patient cohort and in controls. METHODS: The authors screened 197 patients with dystonia (generalized: n = 5; focal/segmental: n = 126; myoclonus-dystonia: n = 34; neuroleptic-induced: n = 32), 435 with PD, and 42 with various other movement disorders, along with 812 healthy controls, for small deletions in exon 5 of DYT1 and tested for exon rearrangements by quantitative, duplex PCR in 51 GAG deletion-negative dystonia cases. RESULTS: The GAG deletion was detected in five patients: three with early-onset PTD, one with generalized jerky or clonic dystonia, and one with generalized dystonia and additional features (developmental delay, pyramidal syndrome). A novel out-of-frame four-bp deletion (934_937delAGAG) in exon 5 of the DYT1 gene was found in a putatively healthy blood donor. No exon rearrangements were identified in DYT1. CONCLUSIONS: In this mixed patient sample, the GAG deletion was rare and in two out of five cases associated with an unusual phenotype. In addition, a novel DYT1 truncating mutation of unknown clinical relevance was found in a putatively unaffected individual. DYT1 exon rearrangements, however, do not seem to be associated with PTD.

Adolescent↗
PubMed2004

Testosterone deficiency and apathy in Parkinson's disease: a pilot study.

BACKGROUND: Low testosterone in men with Parkinson's disease may be associated with non-motor symptoms of the disease, such as apathy. OBJECTIVE: To determine the association between free serum testosterone level and apathy in elderly men with Parkinson's disease. METHODS: Consecutive non-demented patients (n = 49) and knowledgeable informants (n = 40) participated in the study. Patients and informants reported on apathy using the Frontal Systems Behavior Scale and two visual analogue scales. Patients also provided self reported symptoms of depression on the Beck depression inventory-II. Blood samples were drawn at the time of assessment to determine testosterone levels. RESULTS: A low total testosterone concentration was found in 46.9% of the patients, defined as < or = 325 ng/dl. Free testosterone was significantly correlated with both patient reported and informant reported apathy, independent of disease severity. CONCLUSIONS: Apathy is common in Parkinson's disease and is inversely correlated with free testosterone. Testosterone replacement therapy could be considered as a potential treatment for apathy in some men with Parkinson's disease. More research is needed to replicate these findings and to investigate the response to treatment.

Adult↗
PubMed2002

Thrombotic thrombocytopenic purpura as an initial presentation of primary Sjögren's syndrome.

A healthy woman presented with ecchymoses due to thrombocytopenia, with numerous bone marrow megakaryocytes, microangiopathic haemolytic anaemia, disorientation, irritability, and normal renal function. Thrombotic thrombocytopenic purpura (TTP) was diagnosed and treated successfully by plasma exchange therapy, both on presentation and during a further three relapses. The TTP was considered idiopathic until, 4 months later, definite primary Sjogren's syndrome (1 degree SS) was diagnosed following the appearance of sicca symptoms. Only four similar cases have been cited in the literature. TTP should be added to the varied haematological manifestations that may occur in patients with 1 degree SS. The possible presentation of 1 degree SS not with classic sicca symptoms but rather with haematological abnormalities, including TTP, should be recognised.

Female↗
PubMed2002

Agranulocytosis in Sjögren's syndrome: two case reports and analysis of 11 additional reported cases.

OBJECTIVES: To report 2 patients who presented with agranulocytosis that was found to be immune-mediated and associated with occult primary Sjögren's syndrome (primary SS) and to identify and study similar cases reported in the literature. METHODS: Two patients encountered in 2 large medical centers over a period of 5 years were studied in detail. All reported cases of agranulocytosis in primary SS identified through a MEDLINE search were reviewed. RESULTS: Two patients presented with marked systemic symptoms alone or associated with recurrent infections. Agranulocytosis with either a pattern of maturation arrest or a hypercellular reactive bone marrow was found and was associated with "acute phase" markers, hypergammaglobulinemia, a small paraprotein peak, and high rheumatoid factor titers. A diagnosis of immune-mediated agranulocytosis associated with an occult primary SS was established and was successfully treated with intravenous immunoglobulins or prednisone. Both patients subsequently developed skin vasculitis. This rare association of agranulocytosis and Sjögren's syndrome was identified in 11 other cases and was the presenting manifestation of primary SS in 10 of 13 (77%) patients. CONCLUSIONS: Agranulocytosis should be recognized as a rare but well-established association of primary SS. Bone marrow neutrophil production may be affected, or neutrophils may be destroyed in the circulation, by both humoral and cellular immune-mediated mechanisms. Agranulocytosis or neutropenia should be added to the varied hematologic manifestations of primary SS and may be its presenting feature and an important clue to diagnosis.

Aged↗
PubMed2002

Renal ultrasound findings and vesicoureteral reflux in children hospitalised with urinary tract infection.

AIMS: To determine the sensitivity, specificity, and predictive values of renal ultrasound findings for vesicoureteral reflux (VUR). METHODS: Retrospective review of the ultrasound and voiding cystourethrogram (VCUG) results of 162 children under 5 years of age admitted with their first episode of urinary tract infection (UTI) over a two year period. Ultrasound findings were considered suggestive of VUR if "dilatation of the pelvi-calyces", "dilatation of the ureters", or "dilatation of the collecting system" of one or both kidneys was reported. RESULTS: A total of 162 patients were eligible for inclusion (median age 85 days; 71 (44%) were female). The prevalence of VUR was 22%. Ultrasound findings were positive for VUR in 14 of 35 patients with confirmed VUR on VCUG, and positive in 30 of 127 patients without VUR on VCUG. Of 21 patients who had a normal ultrasound but showed VUR on VCUG, 14 had grade II reflux, five grade III reflux, and two grade IV reflux. The sensitivity and specificity of ultrasound in suggesting VUR were 40% and 76%, respectively. The positive predictive value of ultrasound in suggesting VUR was 32%; the negative predictive value was 82%. CONCLUSION: Renal ultrasound findings are neither sensitive nor specific for VUR in children with a first UTI.

Child, Preschool↗
PubMed2001

Lumbar cauda equina syndrome associated with the use of gelfoam: case report.

STUDY DESIGN: A case of cauda equina syndrome is reported. OBJECTIVE: To recognize a serious complication related to the use of Gelfoam in the lumbar spine. SUMMARY AND BACKGROUND DATA: Absorbable hemostatic gelatin sponges have long been used to control bleeding around the spinal cord. Despite widespread use and a safe history with few reported adverse reactions, Gelfoam sponges have potential for complications that may be overlooked. METHOD: A case of cauda equina syndrome is reported and discussed. RESULTS: A retained Gelfoam sponge was found in the epidural space after lumbar decompression and fusion for spinal stenosis. The retained gelatin sponge had expanded and solidified, causing a mass affect. The resultant nerve compression led to progressive myelopathy. On removal of the Gelfoam, symptoms rapidly resolved. CONCLUSIONS: Although the use of Gelfoam in spine surgery generally is considered safe, care must be taken to avoid placing a large mass of sponge in a potentially closed space. If Gelfoam is not handled properly, it can engorge and fail to be resorbed appropriately, thus causing a mass effect. If neurologic compromise develops, Gelfoam should be considered a potential cause and subsequently removed.

Bone Screws↗
PubMed2001

Crystal structures of KDOP synthase in its binary complexes with the substrate phosphoenolpyruvate and with a mechanism-based inhibitor.

The crystal structures of 3-deoxy-D-manno-2-octulosonate-8-phosphate synthase (KDOPS) from Escherichia coli complexed with the substrate phosphoenolpyruvate (PEP) and with a mechanism-based inhibitor (K(d) = 0.4 microM) were determined by molecular replacement using X-ray diffraction data to 2.8 and 2.3 A resolution, respectively. Both the KDOPS.PEP and KDOPS.inhibitor complexes crystallize in the cubic space group I23 with cell constants a = b = c = 117.9 and 117.6 A, respectively, and one subunit per asymmetric unit. The two structures are nearly identical, and superposition of their Calpha atoms indicates an rms difference of 0.41 A. The PEP in the KDOPS.PEP complex is anchored to the enzyme in a conformation that blocks its si face and leaves its re face largely devoid of contacts. This results from KDOPS's selective choice of a PEP conformer in which the phosphate group of PEP is extended toward the si face. Furthermore, the structure reveals that the bridging (P-O-C) oxygen atom and the carboxylate group of PEP are not strongly hydrogen-bonded to the enzyme. The resulting high degree of negative charge on the carboxylate group of PEP would then suggest that the condensation step between PEP and D-arabinose-5-phosphate (A5P) should proceed in a stepwise fashion through the intermediacy of a transient oxocarbenium ion at C2 of PEP. The molecular structural results are discussed in light of the chemically similar but mechanistically distinct reaction that is catalyzed by the enzyme 3-deoxy-D-arabino-2-heptulosonate-7-phosphate synthase and in light of the preferred enzyme-bound states of the substrate A5P.

Aldehyde-Lyases↗
PubMed2001

The binding of the circumsporozoite protein to cell surface heparan sulfate proteoglycans is required for plasmodium sporozoite attachment to target cells.

The major surface protein of malaria sporozoites, the circumsporozoite protein, binds to heparan sulfate proteoglycans on the surface of hepatocytes. It has been proposed that this binding event is responsible for the rapid and specific localization of sporozoites to the liver after their injection into the skin by an infected anopheline mosquito. Previous in vitro studies performed under static conditions have failed to demonstrate a significant role for heparan sulfate proteoglycans during sporozoite invasion of cells. We performed sporozoite attachment and invasion assays under more dynamic conditions and found a dramatic decrease in sporozoite attachment to cells in the presence of heparin. In contrast to its effect on attachment, heparin does not appear to have an effect on sporozoite invasion of cells. When substituted heparins were used as competitive inhibitors of sporozoite attachment, we found that sulfation of the glycosaminoglycan chains at both the N- and O-positions was important for sporozoite adhesion to cells. We conclude that the binding of the circumsporozoite protein to hepatic heparan sulfate proteoglycans is likely to function during sporozoite attachment in the liver and that this adhesion event depends on the sulfated glycosaminoglycan chains of the proteoglycans.

Animals↗
PubMed2001

Absence of germline infection in male mice following intraventricular injection of adenovirus.

The possibility of inadvertent exposure of gonadal tissue to gene therapy vectors has raised safety concerns about germline infection. We show here that the receptor for coxsackie B viruses and adenoviruses 2 and 5 (CXADR) is expressed in mouse germ cells, suggesting the possibility that these viruses could infect germ cells. To directly assess the risk of germline infection in vivo, we injected an adenovirus carrying the germ-cell-specific protamine promoter fused to the bacterial lacZ reporter gene into the left ventricular cavity of mice and then monitored expression of the reporter gene in germ cells. To differentiate between infection of stem cells and differentiating spermatogenic cells, we analyzed expression of the reporter cassette at different times after viral delivery. Under all conditions tested, mice did not express the Escherichia coli beta-galactosidase protein in developing spermatids or in mature epididymal spermatozoa. Primary germ cells cultured in vitro were also refractory to adenoviral infection. Our data suggest that the chance of vertical germline transmission and insertional mutagenesis is highly unlikely following intracoronary adenoviral delivery.

Adenoviridae↗
PubMed2001

Novel mutation in the TOR1A (DYT1) gene in atypical early onset dystonia and polymorphisms in dystonia and early onset parkinsonism.

Dystonia is a movement disorder involving sustained muscle contractions and abnormal posturing with a strong hereditary predisposition and without a distinct neuropathology. In this study the TOR1A (DYT1) gene was screened for mutations in cases of early onset dystonia and early onset parkinsonism (EOP), which frequently presents with dystonic symptoms. In a screen of 40 patients, we identified three variations, none of which occurred in EOP patients. Two infrequent intronic single base pair (bp) changes of unknown consequences were found in a dystonia patient and the mother of an EOP patient. An 18-bp deletion (Phe323_Tyr328del) in the TOR1A gene was found in a patient with early onset dystonia and myoclonic features. This deletion would remove 6 amino acids close to the carboxy terminus, including a putative phosphorylation site of torsinA. This 18-bp deletion is the first additional mutation, beyond the GAG-deletion (Glu302/303del), to be found in the TOR1A gene, and is associated with a distinct type of early onset dystonia.

Adolescent↗
PubMed2001

DPKQDFMRFamide expression is similar in two distantly related Drosophila species.

Drosophila melanogaster DPKQDFMRFamide was isolated and its expression reported. Distribution of DPKQDFMRFamide immunoreactivity is now described in Drosophila virilis. DPKQDFMRFamide antibody stained a cell in the subesophageal ganglion in embryo. DPKQDFMRFamide antibody stained cells in the superior protocerebrum, subesophageal ganglion, thoracic ganglia, and an abdominal ganglion in larva, pupa, and adult. DPKQDFMRFamide antibody stained an additional pair of cells in the optic lobe and a cell in the lateral protocerebrum in adult. Structure identity and similar distribution of DPKQDFMRFamide in D. virilis and D. melanogaster, two distantly related Drosophila species, suggests an important and conserved activity for the peptide.

Animals↗
PubMed2001

Dystonia and its disorders.

Dystonia is a movement disorder characterized by sustained muscle contractions, frequently causing twisting and repetitive movements or abnormal postures. The term dystonia does not signify a single disease, but instead describes a symptom and sign that may be part of many disorders with a variety of causes. Dystonia may be classified by age of onset, distribution of symptoms, or by etiology. An increasing number of genetic forms of dystonia have been recognized and the findings have advanced knowledge of underlying neural mechanisms of pathogenesis. Options for treatment of dystonia include pharmacological therapy, botulinum toxin injection, or neurosurgical procedures.

Diagnosis, Differential↗