Currently, considerable research activities are focussing on biochemical, physiological and pathological aspects of the creatine kinase (CK)-phosphorylcreatine (PCr)-creatine (Cr) system (for reviews see [1,2]), but only little effort is directed towards a thorough investigation of Cr metabolism as a whole. However, a detailed knowledge of Cr metabolism is essential for a deeper understanding of bioenergetics in general and, for example, of the effects of muscular dystrophies, atrophies, CK deficiencies (e.g. in transgenic animals) or Cr analogues on the energy metabolism of the tissues involved. Therefore, the present article provides a short overview on the reactions and enzymes involved in Cr biosynthesis and degradation, on the organization and regulation of Cr metabolism within the body, as well as on the metabolic consequences of 3-guanidinopropionate (GPA) feeding which is known to induce a Cr deficiency in muscle. In addition, the phenotype of muscles depleted of Cr and PCr by GPA feeding is put into context with recent investigations on the muscle phenotype of 'gene knockout' mice deficient in the cytosolic muscle-type M-CK.

Animals↗

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Sequence homology and structure predictions of the creatine kinase isoenzymes.

Comparisons of the protein sequences and gene structures of the known creatine kinase isoenzymes and other guanidino kinases revealed high homology and were used to determine the evolutionary relationships of the various guanidino kinases. A 'CK framework' is defined, consisting of the most conserved sequence blocks, and 'diagnostic boxes' are identified which are characteristic for anyone creatine kinase isoenzyme (e.g. for vertebrate B-CK) and which may serve to distinguish this isoenzyme from all others (e.g. from M-CKs and Mi-CKs). Comparison of the guanidino kinases by near-UV and far-UV circular dichroism further indicates pronounced conservation of secondary structure as well as of aromatic amino acids that are involved in catalysis.

Amino Acid Sequence↗

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Early hospital discharge of children with fever and neutropenia: a prospective study.

PURPOSE: We report a prospective study on brief IV antibiotic therapy in selected children with cancer experiencing fever and neutropenia (FN) after chemotherapy. PATIENTS AND METHODS: All children with FN (T degree > or = 38 degrees C; ANC < 0.5 x 10(9)/L) were hospitalized for treatment with broad spectrum IV antibiotics. They were divided into three groups: group A (no infection), group B (clinically documented infection), and group C (bacteremia). Children in group A (and some children in group B) were discharged before recovery of neutropenia, if afebrile and in good condition. RESULTS: Eighty-eight consecutive episodes of FN occurred in 30 children. Children in group A (44 episodes; 50%) received IV antibiotics for a median of 3 days; on 25 occasions (57%), IV antibiotics were stopped before recovery of neutropenia. In children in group B (30 episodes; 34%), early discharge was allowed in eight cases of minor infections (27%); six received oral antibiotics. Two children (group A) were rehospitalized for recurrent FN but recovered without complications. CONCLUSION: In chemotherapy-induced neutropenia, children hospitalized for fever but without documented infections and some children with minor infections can cautiously be discharged before evidence of bone marrow recovery if afebrile and in good general condition.

Anti-Bacterial Agents↗

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Turner's syndrome and hypogonadotrophic hypogonadism: thalassemia major and hemochromatosis.

We report here the first case of an association between thalassemia major, hemochromatosis, hypogonadotrophic hypogonadism and Turner's syndrome. The patient is an Albanese girl born in 1980; thalassemia major was diagnosed at 1 year and she was started on a transfusion program; in 1987 iron chelation therapy was started. Six years ago, at 7 years of age, her short stature was observed and she was referred to the endocrinology clinic for evaluation; the basal and stimulation tests done at that time failed to reveal growth hormone deficiency, hypothyroidism or any other disease. Nevertheless, at 12 years old, she was still prepubertal and there was a bone age delay of 1.5 years; a gonadotropin-releasing hormone (GnRH) stimulation test showed no response of either FSH (basal: 0.2 mU/ml; peak: 0.8 mU/ml) or LH (basal: < 0.1 mU/ml; peak: 0.6 mU/ml), suggesting hypogonadotrophic hypogonadism. Small dysmorphies called our attention to the possibility of Turner's syndrome which was confirmed by the karyotype (45 XO/46 XX). In this patient, thalassemia major and its lifelong consequences, namely the hemochromatosis-related hypogonadotrophic hypogonadism, masked the usual hormonal findings of Turner's syndrome.

Adolescent↗