Metaplastic breast cancer: a presentation of two cases and a review of the literature.

Metaplastic breast cancer has been difficult to diagnose and classify for a number of reasons. Its rarity prevents any important conclusions to be made, such as factors determining prognosis, immunohistochemistry patterns and successful treatment regimens. Here a number of studies of metaplastic breast cancer are discussed, along with the presentation of two cases.

Metaplastic breast cancer: a presentation of two cases and a review of the literature.

Metaplastic breast cancer has been difficult to diagnose and classify for a number of reasons. Its rarity prevents any important conclusions to be made, such as factors determining prognosis, immunohistochemistry patterns and successful treatment regimens. Here a number of studies of metaplastic breast cancer are discussed, along with the presentation of two cases.

Carcinosarcoma of the ovary: case report and literature review.

Ovarian carcinosarcoma is a rare and aggressive tumor; patients diagnosed with this cancer are usually given a poor prognosis of under three years. It consists of malignant epithelial and stromal elements. Because this tumor is so rare, the most effective route of chemotherapy has not been determined. We introduce a case of a 54-year-old woman diagnosed with carcinosarcoma of the ovary and review the literature discussing trends of the disease and optimal treatment options.

Bench meets bedside: a 10-year-old girl and amino acid residue glycine 75 of the facilitative glucose transporter GLUT1.

In 2000, amino acid residue G75 of the facilitative glucose transporter GLUT1 was identified by mutagenesis as being essential for transport function [Olsowski, A., et al. (2000) Biochemistry 39, 2469-74]. In 2002, we identified a heterozygous missense mutation substituting glycine at residue 75 for tryptophan in a 10-year-old girl with intractable seizures and low glucose concentrations in the cerebrospinal fluid indicative of GLUT1 deficiency. Glucose uptake into erythrocytes of the patient was 36% of controls, and GLUT1-specific immunoreactivity was normal, indicating a functional GLUT1 defect. In silico three-dimensional modeling of the G75W mutant provided a smaller gyration radius for transmembrane segment 2 as the potential pathogenic mechanism in this patient. This case illustrates a GLUT1 mutation characterized in vitro and later confirmed by disease itself and highlights the potential of basic science and clinical medicine to collaborate for the benefit of patients.

Clinical presentation, EEG studies, and novel mutations in two cases of GLUT1 deficiency syndrome in Japan.

We report the first two Japanese children diagnosed with glucose transporter type 1 (GLUT1) deficiency syndrome. Both boys had been treated under the initial diagnosis of epilepsy and were reinvestigated for previously unexplainable hypoglycorrhachia. Myoclonic seizures developed at 4 months of age in Patient #1 (7 years old), and at 2 months of age in Patient #2 (11 years old), followed by cerebellar ataxia, spastic diplegia, and mental retardation. Both patients had hypoglycorrhachia, and the symptoms were more severe in the latter. CSF and serum glucose levels determined simultaneously showed a CSF/serum glucose ratio of below 0.4 in both patients. In mildly affected Patient #1, the postprandial waking EEG showed improvement in the background activity, as compared to that recorded after overnight fasting, while no significant changes were observed in severely affected Patient #2. In both patients, the functional GLUT1 defect was confirmed by 3-O-methyl-D-glucose uptake into erythrocytes. Molecular analyses identified heterozygous novel mutations in both patients, within exons 6 and 2 of the GLUT1 gene, respectively. The ketogenic diet was refused in Patient #1, but started in Patient #2 with significant clinical benefit. Fasting CSF analysis and pre-/postprandial EEG changes in children with epileptic seizures and unexplainable neurological deterioration help in diagnosing this potentially treatable disorder.

Functional consequences of an in vivo mutation in exon 10 of the human GLUT1 gene.

The functional consequences of an in vivo heterozygous insertion mutation in the human facilitated glucose transporter isoform 1 (GLUT1) gene were investigated. The resulting frameshift in exon 10 changed the primary structure of the C-terminus from 42 in native GLUT1 to 61 amino acid residues in the mutant. Kinetic studies on a patient's erythrocytes were substantiated by expressing the mutant cDNA in Xenopus laevis oocytes. K(m) and V(max) values were clearly decreased explaining pathogenicity. Targeting to the plasma membrane was comparable between mutant and wild-type GLUT1. Transport inhibition by cytochalasin B was more effective in the mutant than in the wild-type transporter. The substrate specificity of GLUT1 remained unchanged.