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Biomedical subjects

M Rossiter

Publications and source records attributed to M Rossiter.

16 recordsLinked to original sources

Single base deletion in exon 7 of the glycosylasparaginase gene causes a mild form of aspartylglycosaminuria in a patient of Mauritian origin.

Aspartylglycosaminuria (AGU) is a lysosomal storage disorder of glycoprotein degradation caused by deficiency of glycosylasparaginase (GA). A deletion mutation was found in a mildly affected AGU patient whose parents are first-cousins of Mauritian origin. One bp deletion at position 787 or 788 (delta T788) in exon 7 of the GA gene resulted in a frameshift and produced an immediate stop codon. The resulting truncated polypeptide was defective in its post-translational proteolytic processing and remained as a single chain (36 kDa) with no GA activity.

Acetylglucosamine↗

The natural history of human dermatosparaxis (Ehlers-Danlos syndrome type VIIC).

Dermatosparaxis (Ehlers-Danlos syndrome type VIIC) has only recently been identified in human subjects. Although well documented in animals, to date only three human cases have been recorded, all aged 2 years or under. We document a 15-year-old girl with this newly recognized condition to emphasize the remarkable similarity of physical signs in all four cases. The striking skin fragility which attends the phenotype is highly distinctive, so that the diagnosis may be suspected on clinical grounds. The confirmatory diagnostic procedures are discussed.

Adolescent↗

Transcobalamin I as a "marker" for fibrolamellar hepatoma.

A 12 year old girl with a localised fibrolamellar hepatoma had a raised serum unsaturated vitamin B12 binding capacity (UBBC) and transcobalamin I (TCI) prior to complete resection and chemotherapy. Regular clinical and radiological follow-up detected no recurrence of her disease, but the UBBC and TCI slowly rose. Local recurrence and pulmonary metastases became detectable 2 1/2 years after diagnosis, 18 months after the UBBC and TCI level became elevated. Measurement of UBBC and TCI can help in the early detection of recurrence long before there is clinical or radiological evidence of recurrent fibrolamellar hepatoma.

Carcinoma, Hepatocellular↗

Effect of endurance swimming on rat cardiac myofibrillar ATPase with experimental diabetes.

Diabetes is characterized by depressed cardiac functional properties attributed to Ca2+-activated ATPase activity. In contrast, endurance swimming enhances the cardiac functional properties and Ca2+-activated myofibril ATPase. Thus, the purpose of this study was to observe if the changes associated with experimental diabetes can be ameliorated with training. Diabetes was induced with a single i.v. injection of streptozotocin (60 mg/kg). Blood and urine glucose concentrations were 802 +/- 44 and 6965 +/- 617 mg/dL, respectively. The training control and training diabetic animals were made to swim (+/- 2% body weight) 4 days/week for 8 weeks. Cardiac myofibril, at 10 microM free Ca2+ concentration was reduced by 54% in the sedentary diabetics compared with sedentary control animals (p less than 0.05). Swim training enhanced the Ca2+-activated myofibril ATPase activities for the normal animals. The diabetic animals, which swam for 8 weeks, had further reduced their Ca2+-activated myofibril ATPase activity when compared with sedentary diabetics (p less than 0.05). Similarly, the Mg2+-stimulated myofibril ATPase activity was depressed by 31% in diabetics following endurance swimming. It is concluded that the depressed Ca2+-activated myofibril ATPase activity of diabetic hearts is not reversible with endurance swimming.

Animals↗

Myofibril ATPase activity of cardiac and skeletal muscle of exhaustively exercised rats.

The activation characteristics of Mg-ATP and Ca2+ on cardiac and skeletal muscle myofibril ATPase activity were studied in rats following a run to exhaustion. In addition, the effect of varying ionic strength was determined on skeletal muscle from exhausted animals. The exhausted group (E) ran at a speed of 25 m min-1 with an 8% incline. Myofibril ATPase activities for control (C) and E were determined with 1, 3 and 5 mM Mg-ATP and 1 and 10 microM Ca2+ at pH 7.0 and 30 degrees C. For control skeletal muscle, at 1 and 10 microM Ca2+, there was an increase in ATPase activity from 1 to 5 mM Mg-ATP (P less than 0.05). For E animals the myofibril ATPase activities at 10 microM Ca2+ and all Mg-ATP concentrations were similar to C (P greater than 0.05). At 1.0 microM Ca2+ and all Mg-ATP concentrations were similar to C (P greater than 0.05). At 1.0 microM Ca2+ the activities at 3 and 5 mM Mg-ATP were greater for the E animals (P less than 0.05). Increasing KCl concentrations resulted in greater inhibition for E animals. With cardiac muscle, the myofibril ATPase activities at 1.0 microM free Ca2+ were lower for E at all Mg-ATP levels (P less than 0.05). In contrast, at 10 microM Ca2+, the E group exhibited an elevated myofibril ATPase activity. The results indicate that Mg-ATP and Ca2+ activation of cardiac and skeletal muscle myofibril ATPase is altered with exhaustive exercise.

Adenosine Triphosphatases↗

Complete recovery of histiocytic medullary reticulosis-like syndrome in a child with acute lymphoblastic leukemia.

A 6-year-old boy with acute lymphoblastic leukemia (ALL) developed a haemophagocytic syndrome resembling histiocytic medullary reticulosis (HMR) but made a complete recovery on supportive treatment. This was subsequently found to have been associated with a parainfluenzal infection. It is suggested that HMR in immunocompromised hosts may represent a reactive process to an opportunistic viral infection and that the use of chemotherapy in these patients may be deleterious.

Child↗

Calcium activation of sarcoplasmic reticulum ATPase following strenuous activity.

The purpose of this study was to examine the effects of varying Ca2+ activated sarcoplasmic reticulum (SR) ATPase activity of fast-twitch (FT) skeletal muscle at exhaustion and during recovery. Wistar rats (200 g) were assigned to control (C), exhausted (E), and three recovery groups (R) at 5, 15, and 30 min. Following exhaustion on a motor-driven treadmill, the gastrocnemius muscles from all groups were excised and frozen. Muscle samples were assayed for ATPase activity in a Ca2+-ethyleneglycol bis (beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA) buffering system. At 1.25 microM Ca2+, a significant depression in Ca2+ activated ATPase activity occurred in the E, 5R, 15R, and 30R groups (1.61 +/- 0.17, 1.87 +/- 0.14, 1.43 +/- 0.29, and 1.62 +/- 0.1 mumol Pi . mg-1 . 10 min-1) compared with C values (2.41 +/- 0.34 mumol Pi . mg-1 . 10 min-1) (p less than or equal to 0.05). At 5.0 microM, Ca2+ activated ATPase activity remained depressed in the E, 5R, and 15R groups compared with C and 30R groups (p less than or equal to 0.05). At 0.75 microM Ca2+, there was no significant difference between groups (p greater than or equal to 0.05). The results suggest that Ca2+ activated SR ATPase activity of fatigued FT muscle may contribute to the decreased force production at exhaustion.

Adenosine Triphosphatases↗

Chemical ionization and field desorption mass spectrometry of the gentamicins.

Gentamicin sulphate employed in therapeutics consists of a mixture of three major aminoglycoside components, the gentamicins C1, C1a and C2. In the electron impact mass spectra of these components weak parent ions may be observed but they are of no diagnostic value in the commercial mixture. Chemical ionization and field desorption spectra of individual gentamicin components and commercial mixtures are reported and discussed. Isobutane chemical ionization spectra exhibit some fragmentation, but under optimum field desorption conditions little glycosidic cleavage is observed and [M + H]+ ions dominate the spectra.

Amines↗

Yersinia enterocolitis in iron overload.

Yersinia enterocolitis with peritonitis and septicaemia developed in a 4-year-old child with thalassemia intermedia and iron overload. It is likely that the illness was exacerbated by continued administration of desferrioxamine, a bacterial siderophore, which facilitated systemic spread of Yersinia. It is recommended that Yersinia enterocolitis be considered in children with iron overload and that desferrioxamine be discontinued and prophylactic antibiotics be administered while Yersinia is sought.

Child, Preschool↗